Fischer-Tropsch Refining

Arno de Klerk Fischer–Tropsch Refining

Further Reading Arpe, Hans-Jurgen ¨

Kolb, G.

Industrial Organic Chemistry

Fuel Processing

5th, completely revised edition

for Fuel Cells

2010

2008

Hardcover

Hardcover

ISBN: 978-3-527-32002-8

ISBN: 978-3-527-31581-9

Wijngaarden, Ruud I./Westerterp, K. Roel/Kronberg, Alexander/Bos, A.N.R. (Eds.)

Deublein, D., Steinhauser, A.

Industrial Catalysis Optimizing Catalysts and Processes

Biogas from Waste and Renewable Resources An Introduction 2011

2011 Hardcover

Hardcover ISBN: 978-3-527-32798-0

ISBN: 978-3-527-31837-7

Olah, G. A., Goeppert, A., Prakash, G. K. S.

Beyond Oil and Gas: The Methanol Economy

H¨aring, H.-W. (Ed.)

Industrial Gases Processing 2008 Hardcover

2010

ISBN: 978-3-527-31685-4

Softcover ISBN: 978-3-527-32422-4

Barbaro, P., Bianchini, C. (Eds.)

Catalysis for Sustainable Energy Production 2009 Hardcover ISBN: 978-3-527-32095-0

Stolten, D. (Ed.)

Hydrogen and Fuel Cells Fundamentals, Technologies and Applications 2010 Hardcover ISBN: 978-3-527-32711-9

Al-Qahtani, Khalid Y./Elkamel, Ali

Planning and Integration of Refinery and Petrochemical Operations 2010 Hardcover ISBN: 978-3-527-32694-5

Elvers, B. (Ed.)

Handbook of Fuels 2008 Hardcover ISBN: 978-3-527-30740-1

Arno de Klerk

Fischer–Tropsch Refining

The Author Arno de Klerk University of Alberta Chemical and Materials Engineering Edmonton, Alberta, T6G 2V4 Canada

All books published by Wiley-VCH are carefully produced. Nevertheless, authors, editors, and publisher do not warrant the information contained in these books, including this book, to be free of errors. Readers are advised to keep in mind that statements, data, illustrations, procedural details or other items may inadvertently be inaccurate. Library of Congress Card No.: applied for British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. Bibliographic information published by the Deutsche Nationalbibliothek The Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data are available on the Internet at .  2011 Wiley-VCH Verlag & Co. KGaA, Boschstr. 12, 69469 Weinheim, Germany

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V

To my wife, Ch`erie, who loves and supports me so much.

VII

Contents Preface Part I

XIX Introduction

1

1 1.1 1.2 1.2.1 1.2.2 1.2.3 1.3 1.4 1.4.1 1.4.2 1.4.3 1.5 1.5.1 1.5.2 1.5.3

Fischer–Tropsch Facilities at a Glance 3 Introduction 3 Feed-to-Syngas Conversion 4 Feed Logistics and Feed Preparation 5 Syngas Production 5 Syngas Cleaning and Conditioning 7 Syngas-to-Syncrude Conversion 8 Syncrude-to-Product Conversion 10 Upgrading versus Refining 10 Fuels versus Chemicals 11 Crude Oil Compared to Syncrude 12 Indirect Liquefaction Economics 14 Feed Cost 14 Product Pricing 15 Capital Cost 17 References 19

2 2.1 2.2 2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.2.6 2.3 2.3.1 2.4

Refining and Refineries at a Glance 21 Introduction 21 Conventional Crude Oil 22 Hydrocarbons in Crude Oil 23 Sulfur Compounds in Crude Oil 23 Nitrogen Compounds in Crude Oil 25 Oxygenates in Crude Oil 25 Metals in Crude Oil 26 Physical Properties 27 Products from Crude Oil 28 Boiling Range and Product Quality 29 Evolution of Crude Oil Refineries 31

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Contents

2.4.1 2.4.2 2.4.3 2.4.4 2.4.5 2.4.6

First-Generation Crude Oil Refineries 32 Second-Generation Crude Oil Refineries 33 Third-Generation Crude Oil Refineries 36 Fourth-Generation Crude Oil Refineries 39 Petrochemical Refineries 43 Lubricant Base Oil Refineries 44 References 46 Part II

Production of Fischer–Tropsch Syncrude

49

3 3.1 3.2 3.2.1 3.2.2 3.3 3.3.1 3.3.2 3.3.3 3.3.4 3.3.5 3.4 3.4.1 3.4.2 3.4.3 3.4.4 3.4.5 3.5 3.5.1 3.6 3.6.1 3.7

Synthesis Gas Production, Cleaning, and Conditioning 51 Introduction 51 Raw Materials 51 Natural Gas 51 Solid Carbon Sources 52 Syngas from Natural Gas 53 Natural Gas Cleaning 55 Adiabatic Prereforming 55 Steam Reforming 56 Adiabatic Oxidative Reforming 56 Gas Reforming Comparison 57 Syngas from Solid Carbon Sources 58 Gasification of Heteroatoms 59 Low-Temperature Moving Bed Gasification 60 Medium-Temperature Fluidized Bed Gasification 62 High-Temperature Entrained Flow Gasification 64 Gasification Comparison 66 Syngas Cleaning 66 Acid Gas Removal 67 Syngas Conditioning 69 Water Gas Shift Conversion 69 Air Separation Unit 70 References 71

4 4.1 4.2 4.3 4.3.1 4.3.2 4.3.3 4.4 4.4.1 4.4.2 4.4.3

Fischer–Tropsch Synthesis 73 Introduction 73 Fischer–Tropsch Mechanism 74 Fischer–Tropsch Product Selectivity 77 Probability of Chain Growth 78 Hydrogenation versus Desorption 80 Readsorption Chemistry 81 Selectivity Manipulation in Fischer–Tropsch Synthesis Fischer–Tropsch Catalyst Formulation 81 Fischer–Tropsch Operating Conditions 83 Fischer–Tropsch Reaction Engineering 84

81

Contents

4.5 4.5.1 4.5.2 4.5.3 4.5.4 4.5.5 4.5.6 4.5.7

Fischer–Tropsch Catalyst Deactivation 88 Poisoning by Syngas Contaminants 89 Volatile Metal Carbonyl Formation 90 Metal Carboxylate Formation 91 Mechanical Catalyst Degradation 92 Deactivation of Fe-HTFT Catalysts 93 Deactivation of Fe-LTFT Catalysts 93 Deactivation of Co-LTFT Catalysts 95 References 99

5 5.1 5.2 5.2.1 5.2.2 5.3 5.3.1 5.3.2 5.3.3 5.3.4 5.3.5

Fischer–Tropsch Gas Loop 105 Introduction 105 Gas Loop Configurations 107 Open Gas Loop Design 107 Closed Gas Loop Design 108 Syncrude Cooling and Separation Pressure Separation 110 Cryogenic Separation 110 Oxygenate Partitioning 111 HTFT Syncrude Recovery 113 LTFT Syncrude Recovery 114 References 116 Part III

109

Industrial Fischer–Tropsch Facilities

6 6.1 6.2 6.3 6.3.1 6.3.2 6.3.3 6.3.4 6.4 6.4.1 6.4.2 6.4.3 6.4.4 6.4.5 6.5

German Fischer–Tropsch Facilities 119 Introduction 119 Synthesis Gas Production 119 Fischer–Tropsch Synthesis 121 Normal-Pressure Synthesis 122 Medium-Pressure Synthesis 125 Gas Loop Design 127 Carbon Efficiency 128 Fischer–Tropsch Refining 128 Refining C3 –C4 Crude LPG 129 Refining Carbon Gasoline 130 Refining of Condensate Oil 132 Refining of Waxes 135 Aqueous Product Refining 136 Discussion of the Refinery Design 137 References 138

7 7.1 7.2

American Hydrocol Facility 141 Introduction 141 Synthesis Gas Production 142

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Contents

7.3 7.4 7.4.1 7.4.2 7.5

Fischer–Tropsch Synthesis 143 Fischer–Tropsch Refining 145 Oil Product Refining 146 Refining Aqueous Product 149 Discussion of the Refinery Design 150 References 151

8 8.1 8.2 8.2.1 8.2.2 8.3 8.3.1 8.3.2 8.3.3 8.4 8.4.1 8.4.2 8.4.3 8.4.4 8.4.5 8.5 8.5.1 8.5.2 8.5.3 8.5.4 8.6

Sasol 1 Facility 153 Introduction 153 Synthesis Gas Production 154 Lurgi Dry Ash Coal Gasification 154 Rectisol Synthesis Gas Cleaning 155 Fischer–Tropsch synthesis 157 Kellogg HTFT synthesis 157 Arge LTFT Synthesis 159 Gas Loop Design 162 Fischer–Tropsch Refining 163 Kellogg HTFT Oil Refining 163 Arge LTFT Oil Refining 165 Aqueous Product Refining 166 Coal Pyrolysis Product Refining 169 Synthetic Fuel Properties 170 Evolution of the Sasol 1 Facility 172 Changes in Synthesis Gas Production 172 Changes in Fischer–Tropsch Synthesis 173 Changes in Fischer–Tropsch Refining 174 Changes in Coal Pyrolysis Product Refining 177 Discussion of the Refinery Design 177 References 179

9 9.1 9.2 9.2.1 9.2.2 9.3 9.3.1 9.4 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 9.5 9.5.1

Sasol 2 and 3 Facilities 181 Introduction 181 Synthesis Gas Production 182 Lurgi Dry Ash Coal Gasification 182 Synthesis Gas Cleaning 182 Fischer–Tropsch Synthesis 183 Gas Loop Design 184 Fischer–Tropsch Refining 186 Synthol HTFT Condensate Refining 188 Synthol HTFT Oil Refining 192 Aqueous Product Refining 194 Coal Pyrolysis Product Refining 196 Synthetic Fuel Properties 198 Evolution of Sasol Synfuels 199 Changes in Synthesis Gas Production 201

Contents

9.5.2 9.5.3 9.5.4 9.5.5 9.5.6 9.5.7 9.5.8 9.6

Changes in Fischer–Tropsch Synthesis 201 Changes in Fischer–Tropsch Condensate Refining 202 Extraction of Linear 1-Alkenes 204 Changes in Fischer–Tropsch Oil Refining 205 Changes in Fischer–Tropsch Aqueous Product Refining 210 Changes in Coal Pyrolysis Product Refining 211 Synthetic Jet Fuel 212 Discussion of the Refinery Design 212 References 214

10 10.1 10.2 10.2.1 10.2.2 10.3 10.3.1 10.4 10.4.1 10.4.2 10.4.3 10.5 10.5.1 10.5.2 10.6

Mossgas Facility 217 Introduction 217 Synthesis Gas Production 218 Natural Gas Liquid Recovery 218 Gas Reforming 218 Fischer–Tropsch Synthesis 220 Gas Loop Design 221 Fischer–Tropsch Refining 222 Oil Refining 222 Aqueous Product Refining 225 Synthetic Fuel Properties 227 Evolution of the PetroSA Facility 227 Addition of Low-Temperature Fischer–Tropsch Synthesis 227 Changes in the Fischer–Tropsch Refinery 227 Discussion of the Refinery Design 228 References 229

11 11.1 11.2 11.3 11.4 11.4.1 11.4.2 11.5 11.6

Shell Middle Distillate Synthesis (SMDS) Facilities 231 Introduction 231 Synthesis Gas Production in Bintulu GTL 232 Fischer–Tropsch Synthesis in Bintulu GTL 233 Fischer–Tropsch Refining in Bintulu GTL 235 Oil Refining 235 Aqueous Product Treatment 238 Pearl GTL Facility 238 Discussion of the Refinery Design 239 References 239

12 12.1 12.2 12.3 12.4 12.4.1 12.4.2

Oryx and Escravos Gas-to-Liquids Facilities 241 Introduction 241 Synthesis Gas Production in Oryx GTL 242 Fischer–Tropsch Synthesis in Oryx GTL 243 Fischer–Tropsch Refining in Oryx GTL 244 Oil Refining 244 Aqueous Product Treatment 247

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XII

Contents

12.5

Discussion of the Refinery Design 247 References 248 Part IV

Synthetic Transportation Fuels

249

13 13.1 13.2 13.3 13.3.1 13.3.2 13.3.3 13.3.4 13.3.5 13.3.6 13.3.7 13.3.8 13.3.9 13.4 13.5

Motor-Gasoline 251 Introduction 251 Motor-Gasoline Specifications 252 Motor-Gasoline Properties 253 Octane Number 253 Density 259 Volatility 259 Fuel Stability 261 Alkene Content 261 Aromatic Content 262 Sulfur Content 262 Oxygenate Content 262 Metal Content 263 Aviation-Gasoline 264 Future Motor-Gasoline Specification Changes References 266

14 14.1 14.2 14.2.1 14.2.2 14.3 14.3.1 14.3.2 14.3.3 14.3.4 14.3.5 14.3.6 14.3.7 14.3.8 14.4

Jet Fuel 269 Introduction 269 Jet Fuel Specifications 270 Synthetic Jet Fuel 271 Fuel for Military Use 272 Jet Fuel Properties 273 Net Heat of Combustion 274 Density and Viscosity 275 Freezing Point Temperature 276 Aromatic Content and Smoke Point 276 Sulfur and Acid Content 278 Volatility 278 Stability 278 Elastomer Compatibility and Lubricity 279 Future Jet Fuel Specification Changes 280 References 280

15 15.1 15.2 15.3 15.3.1 15.3.2

Diesel Fuel 283 Introduction 283 Diesel Fuel Specifications 284 Diesel Fuel Properties 286 Cetane Number 286 Density and Viscosity 290

265

Contents

15.3.3 15.3.4 15.3.5 15.3.6 15.3.7 15.3.8 15.3.9 15.4 15.5

Flash Point 290 Lubricity 290 Aromatic Content 292 Sulfur Content 292 Cold-Flow Properties 293 Stability 294 Elastomer Compatibility 294 Diesel Fuel Additives That Affect Refinery Design 295 Future Diesel Fuel Specification Changes 296 References 297 Part V

16 16.1 16.2 16.2.1 16.2.2 16.3 16.3.1 16.3.2 16.3.3 16.3.4 16.3.5 16.3.6 16.3.7 16.4 16.4.1 16.4.2 16.4.3 16.4.4 16.4.5 16.4.6 16.5 16.5.1 16.5.2 16.5.3 16.5.4 16.6 16.6.1 16.6.2 16.6.3 16.6.4 16.7

Refining Technology 301

Refining Technology Selection 303 Introduction 303 Hydrotreating 305 Hydrogenation of Alkenes 306 Hydrodeoxygenation 307 Addition and Removal of Oxygen 308 Dehydration 308 Etherification 309 Hydration 309 Esterification 310 Carbonyl Aromatization 310 Hydroformylation 311 Autoxidation 311 Alkene Conversion 312 Double Bond Isomerization 312 Metathesis 314 Skeletal Isomerization 314 Oligomerization 315 Aliphatic Alkylation 316 Aromatic Alkylation 317 Alkane Conversion 319 Hydroisomerization 319 Hydrocracking 320 Naphtha Reforming and Aromatization 321 Dehydrogenation 322 Residue Conversion 323 Catalytic Cracking 323 Visbreaking 324 Thermal Cracking 324 Coking 326 Fischer–Tropsch Refining Technology Selection References 328

326

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Contents

17 17.1 17.2 17.2.1 17.2.2 17.2.3 17.3 17.3.1 17.3.2 17.3.3 17.4 17.4.1 17.4.2 17.4.3

Dehydration, Etherification, and Hydration 335 Introduction 335 Dehydration 336 Reaction Chemistry 339 Catalysis 340 Syncrude Process Technology 341 Etherification 343 Reaction Chemistry 345 Catalysis 346 Syncrude Process Technology 347 Hydration 347 Reaction Chemistry 349 Catalysis 349 Syncrude Process Technology 350 References 350

18 18.1 18.2 18.2.1 18.2.2 18.3 18.3.1 18.3.2 18.3.3 18.4 18.4.1 18.4.2 18.4.3 18.4.4

Isomerization 353 Introduction 353 Reaction Chemistry 354 Alkene Skeletal Isomerization 354 Alkane Hydroisomerization 356 Skeletal Isomerization 357 Butene Isomerization Catalysis 358 Pentene Isomerization Catalysis 359 Syncrude Process Technology 360 Hydroisomerization 360 Butane Hydroisomerization Catalysis 362 C5 –C6 Naphtha Hydroisomerization Catalysis 362 Heavy Alkane and Wax Hydroisomerization Catalysis Syncrude Process Technology 364 References 366

19 19.1 19.2 19.3 19.3.1 19.3.2 19.3.3 19.3.4 19.3.5 19.3.6 19.4

Oligomerization 369 Introduction 369 Reaction Chemistry 372 Catalysis 374 Solid Phosphoric Acid 375 H-ZSM-5 Zeolite 378 Amorphous Silica–Alumina 380 Acidic Resin 381 Homogeneous Nickel 383 Thermal Oligomerization 384 Syncrude Process Technology 385 References 388

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Contents

20 20.1 20.2 20.3 20.3.1 20.3.2 20.3.3 20.4

Aromatic Alkylation 393 Introduction 393 Reaction Chemistry 395 Catalysis 396 Aromatic Alkylation with Ethene 397 Aromatic Alkylation with Propene 399 Aromatic Alkylation with C4 and Heavier Alkenes 401 Syncrude Process Technology 403 References 405

21 21.1 21.2 21.2.1 21.2.2 21.2.3 21.3 21.3.1 21.4 21.4.1 21.4.2 21.5 21.5.1 21.5.2

Cracking 407 Introduction 407 Reaction Chemistry 410 Thermal Cracking 410 Catalytic Cracking 414 Hydrocracking 416 Thermal Cracking 419 Syncrude Processing Technology 421 Catalytic Cracking 421 Catalysis 423 Syncrude Processing Technology 425 Hydrocracking 427 Catalysis 430 Syncrude Processing Technology 434 References 436

22 22.1 22.2 22.3 22.3.1 22.3.2 22.3.3 22.4 22.4.1 22.4.2 22.4.3 22.5 22.5.1 22.5.2 22.5.3

Reforming and Aromatization 441 Introduction 441 Thermal Naphtha Reforming 443 Conventional Catalytic Naphtha Reforming 444 Reaction Chemistry 444 Catalysis 447 Syncrude Processing Technology 449 Monofunctional Nonacidic Pt/L-Zeolite Naphtha Reforming 450 Reaction Chemistry 451 Catalysis 452 Syncrude Processing Technology 453 Aromatization 454 Reaction Chemistry 456 Catalysis 457 Syncrude Processing Technology 460 References 461

23 23.1

Chemical Technologies 465 Introduction 465

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Contents

23.2 23.2.1 23.2.2 23.2.3 23.2.4 23.3 23.3.1 23.3.2 23.3.3 23.3.4

Production of n-1-Alkenes (Linear α-Olefins) 466 Extraction of 1-Pentene and 1-Hexene 467 Extraction of 1-Octene 470 Production of 1-Octene from 1-Heptene 473 Distillate-Range n-1-Alkene Extraction 474 Autoxidation 474 Autoxidation Regimes 477 Reaction Chemistry 478 Fischer–Tropsch Wax Oxidation 480 Syncrude Process Technology 484 References 485 Part VI

Refinery Design 489

24 24.1 24.2 24.2.1 24.2.2 24.2.3 24.2.4 24.3 24.3.1 24.3.2 24.3.3 24.3.4 24.4 24.4.1 24.4.2 24.4.3 24.4.4 24.4.5

Principles of Refinery Design 491 Introduction 491 Refinery Design Concepts 491 Characteristic of the Refining Business 491 Complex Systems and Design Rules 493 Refining Complexity 495 Refining Efficiency 496 Conceptual Refinery Design 497 Linear Programming 497 Hierarchical Design 498 Technology Preselection 498 Carbon-Number-Based Design 499 Real-World Refinery Design 500 Refinery Type 501 Refinery Products and Markets 501 Refinery Feed Selection 502 Refinery Location 503 Secondary Design Objectives 506 References 508

25 25.1 25.2 25.2.1 25.2.2 25.2.3 25.3 25.3.1 25.3.2 25.3.3 25.3.4

Motor-Gasoline Refining 509 Introduction 509 Gap Analysis for Syncrude to Motor-Gasoline 510 Motor-Gasoline Specifications 510 Carbon Number Distribution 511 Composition and Quality 512 Decisions Affecting Motor-Gasoline Refining 514 Chemicals Coproduction 514 Fate of C2 –C4 Hydrocarbons 515 Fate of the Residue and Wax 516 Fate of the Aqueous Product 517

Contents

25.3.5 25.3.6 25.3.7 25.4 25.4.1 25.4.2 25.5 25.5.1 25.5.2 25.5.3

Alkane-Based Naphtha Refining 518 Technology Selection 519 Co-refining 521 Motor-Gasoline Refining from HTFT Syncrude 522 HTFT Motor-Gasoline Design Case I 522 HTFT Motor-Gasoline Design Case II 526 Motor-Gasoline Refining from LTFT Syncrude 529 LTFT Motor-Gasoline Design Case I 529 LTFT Motor-Gasoline Design Case II 534 LTFT Motor-Gasoline Design Case III 537 References 539

26 26.1 26.2 26.2.1 26.2.2 26.2.3 26.3 26.3.1 26.3.2 26.3.3 26.3.4 26.4 26.4.1 26.4.2 26.5 26.5.1

Jet Fuel Refining 541 Introduction 541 Gap Analysis for Syncrude to Jet Fuel 541 Jet Fuel Specifications 541 Carbon Number Distribution 542 Composition and Quality 542 Decisions Affecting Jet Fuel Refining 544 Fate of C2 –C4 Hydrocarbons 544 Fate of the Residue and Wax 545 Technology Selection 546 Co-refining 547 Jet Fuel Refining from HTFT Syncrude 548 HTFT Jet Fuel Design Case I 549 HTFT Jet Fuel Design Case II 552 Jet Fuel Refining from LTFT Syncrude 553 LTFT Jet Fuel Design Case I 555 References 558

27 27.1 27.2 27.2.1 27.2.2 27.2.3 27.2.4 27.3 27.3.1 27.3.2 27.3.3 27.3.4 27.3.5 27.3.6 27.4

Diesel Fuel Refining 559 Introduction 559 Gap Analysis for Syncrude to Diesel Fuel 560 Diesel Fuel Specifications 560 Carbon Number Distribution 561 Composition and Quality 562 Density–Cetane–Yield Triangle 563 Decisions Affecting Diesel Fuel Refining 564 Fate of C2 –C4 Hydrocarbons 565 Fate of the Residue and Wax 565 Fate of the Aqueous Product 565 Technology Selection 566 Co-refining 567 Dealing with the Density–Cetane–Yield Triangle Diesel Fuel Refining from HTFT Syncrude 570

569

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Contents

27.4.1 27.5 27.5.1 27.5.2

HTFT Diesel Fuel Design Case I 570 Diesel Fuel Refining from LTFT Syncrude LTFT Diesel Fuel Design Case I 573 LTFT Diesel Fuel Design Case II 576 References 578

28 28.1 28.2 28.2.1 28.2.2 28.3 28.3.1 28.3.2 28.3.3 28.3.4 28.4 28.4.1 28.4.2 28.4.3 28.4.4 28.4.5 28.5 28.5.1 28.5.2 28.5.3

Chemicals and Lubricant Refining 581 Introduction 581 Petrochemical and Lubricant Markets 582 Petrochemicals 582 Lubricants 584 Overview of Chemicals Refining Concepts for Syncrude 585 Alkane-Based Refining 585 Aromatics Production 586 Alkene and Oxygenate Recovery 587 Fuels and Chemicals Coproduction 588 Fischer–Tropsch-Based Petrochemical Refining 591 Alkane Refining 591 Light Alkene Refining 592 Linear 1-Alkene Refining 594 Aromatics Refining 595 Oxygenate Refining 597 Fischer–Tropsch-Based Lubricant Base Oil Refining 597 Group III Lubricant Refining 598 Group IV Lubricant Refining 599 Lubricant Base Oil Refining 600 References 601 Index 603

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Preface Life sometimes takes one on a journey that is quite unanticipated. After graduation, I had dreams of making the world a better place by becoming a forensic scientist. Three years later, life took me down a different path. As a young process engineer the objective changed and I had to console myself with trying to make the world a better place in a different way. Thus started an industrial career in the refining of synthetic liquids. The energy business is tremendously dependent on the crude oil price, which by all accounts seems to be inherently unpredictable. The crude oil price holds the synthetic liquids industry to ransom, as it fluctuates in response to many global forces. Today, coal-to-liquids and gas-to-liquids are economical processes – tomorrow it may not be. So, it goes on and on, and has been going on for many decades. When an idealistic individual is confronted with the realities of the energy business and the fickleness of decisions related to the continuous quest for power and money, it can become frustrating. It is not possible to develop technology for the refining of synthetic liquids in phase with the waxing and waning of the oil price. This in turn leads to inefficient refining practices and creates false impressions about the refining of synthetic liquids. Research is not amenable to the stop–start–stop–start cycles dictated by the economic fortunes of the synthetic liquids industry. The wheel has been reinvented many times over, as know-how is lost in times when indirect liquefaction is not economical. This book is an attempt to present and preserve some of the thinking around the refining of Fischer–Tropsch syncrude in the hope that it will help bridge the stop–start–stop–start interest in indirect liquefaction by Fischer–Tropsch synthesis. There are no other works on this topic, except for the occasional chapter in works on Fischer–Tropsch synthesis. The catalysis related to Fischer–Tropsch refining has been discussed in a recent book by Ed Furimsky and myself that is titled ‘‘Catalysis in the refining of Fischer–Tropsch syncrude.’’ There was a deliberate attempt to avoid duplication of effort and overlap with the aforementioned work. This book focuses on the application of catalysis, the processes, the refining technologies, and the refinery design associated with Fischer–Tropsch syncrude. During the writing of this book, some decisions had to be made. The book also had to deal with shortcomings in the reported literature that could not be overcome by the author’s experience in this field. The intent is not to apologize for these decisions and shortcomings but rather to make the reader aware of them. 1) Throughout the book, the International Union of Pure and Applied Chemistry (IUPAC) chemical nomenclature was employed. This may create a slightly unfamiliar feel for many

XX

Preface

2)

3)

4)

5)

6)

7)

readers from the industry and maybe even some readers from the academia. It is a common occurrence to refer to paraffins (not alkanes) and olefins (not alkenes). Yet, having waded through a fair bit of the older literature on Fischer–Tropsch in writing this book, one appreciates the value of having a consistent nomenclature. It was too often necessary to scrounge around to establish what compound or mixture has been described by a colloquial term that had been in common use 80 years ago, but is quite unfamiliar at present. As concession and in order to improve readability, commonly used trivial names and terms were provided in brackets with the IUPAC nomenclature. In cases where the trivial name is unambiguous and recognized in IUPAC nomenclature, the more familiar name was adopted, for example, o-xylene instead of 1,2-dimethylbenzene. In chemical structures, hydrogen atoms are not indicated unless it improves readability. The symbol ‘‘R’’ denotes an alkyl group or hydrogen and the symbol ‘‘M’’ denotes a metal atom. ` The Systeme International d’Unit´es (SI units) were used, albeit with some exceptions. Temperature is reported in degrees Celsius (◦ C) and not Kelvin (K). The conversion from degrees Celsius to Kelvin is easy, just add 273.15. Kinematic viscosity is reported in centistokes (cSt) and not square meter per second (1 cSt = 1 × 10−6 m2 ·s−1 = 1 mm2 ·s−1 ). Not all rates were converted to a per second basis and more familiar time periods were employed for production capacities and flow rates. Since the topic of the book is on refining, it also became clear that the unit of barrels per day (bbl/day) cannot be avoided (1 bbl = 0.158 987 3 m3 ). In the chapters that discuss transportation fuel specifications, the measurement of fuel properties mainly refers to the American Society for Testing and Materials (ASTM) standard test methods. There are of course equivalent methods from the Institute of Petroleum (IP), International Standards Organization (ISO), and various national institutes. Reference to the one rather than the other implies no value judgment. Transportation fuel specifications are country dependent and are ever changing. No attempt was made to provide an anthology of global specifications, which would in any case become outdated rather quickly. The European motor-gasoline (EN228:2004) and diesel fuel (EN590:2004) specifications were selected as the basis for discussion, with reference to some other specifications, including the World Wide Fuel Charter (WWFC). The same applies to jet fuel, where the DEF-STAN 91-91 Issue 6 has been selected as the basis for discussion. There is no implicit value judgment. The discussion focuses on the fundamentals and the specifications are only illustrative in nature. Refining consists of conversion and separation processes. In the book, there is a definite bias toward conversion processes. This does not imply that separation is less important than conversion, but in many instances the challenge in fuel refining is not efficient separation, but efficient conversion. In petrochemical refining, the roles are sometimes reversed. The bias toward conversion goes hand in hand with the focus. The effort that has been expended in literature to correctly identify and quantify compounds varies considerably. If some compounds or compound classes have not been mentioned in conjunction with a specific topic, it does not necessarily imply that these compounds were not present. In Fischer–Tropsch literature, the oxygenates and especially the aqueous products tend to be ignored or are considered with less care than is bestowed on the organic product. Where possible this bias was rectified, but this was not possible in all instances.

Preface

8) The book ‘‘Catalysis in the refining of Fischer–Tropsch syncrude’’ contains an in-depth discussion on the catalysis needed for the refining of Fischer–Tropsch syncrude. It also contains a review of the patent literature on syncrude refining. References to patent literature and catalysis literature have therefore been kept to a minimum. Nevertheless, some discussion of catalysis in the context of refining could not be avoided, since it is critical to the success of syncrude refining. 9) Although every effort has been made to provide a comprehensive discussion of refining, this book is not a general text on oil refining. Process flow diagrams and schematics have consequently not been provided for every technology, and there was a deliberate attempt not to duplicate material readily available in reference texts on crude oil refining. Details related to general issues, such as the pressure and energy balance over fluid catalytic cracking units, were therefore not discussed unless it had a direct bearing on syncrude refining. 10) A number of sections were devoted to the relationship between crude oil refining, transportation fuel specifications, and syncrude refining. Yet, the focus throughout was on Fischer–Tropsch syncrude refining. It was assumed that the reader has at least a superficial knowledge of the conversion processes employed in crude oil refining. If this is not the case, the narrative will be somewhat more taxing to follow, but should still be understandable. Edmonton, AB, Canada, December 2010

Arno de Klerk

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1

Part I Introduction

Fischer–Tropsch Refining, First Edition. Arno de Klerk.  2011 Wiley-VCH Verlag GmbH & Co. KGaA. Published 2011 by Wiley-VCH Verlag GmbH & Co. KGaA.

3

1 Fischer–Tropsch Facilities at a Glance 1.1 Introduction

Industrial Fischer–Tropsch facilities are currently only used for coal-to-liquid (CTL) and gas-to-liquid (GTL) conversion. The purpose of such facilities is to convert solid or gaseous carbon-based energy sources into products that may be used as fuels or chemicals. Although Fischer–Tropsch synthesis lies at the heart of the conversion, it is actually only a small part of the overall process. The process can be divided into three steps (Figure 1.1): feed-to-syngas conversion, syngas-to-syncrude conversion, and syncrude-to-product conversion. Generically, this is called indirect liquefaction, because the feed is first transformed into synthesis gas (syngas) and the syngas is then transformed into products. From Figure 1.1 it can be seen that the type of feed materials that can be converted in the first step is not restricted to coal and natural gas. The conversion of biomass in a biomass-to-liquids (BTLs) process and waste in a waste-to-liquids (WTLs) process can likewise be considered. Collectively, all of these processes are referred to as feed-to-liquids (XTLs) conversion processes. The raw feed material limits the technology selection for the feed-to-syngas conversion step, but not for the subsequent steps. Once the feed has been converted into syngas, which is a mixture of carbon monoxide (CO) and hydrogen (H2 ), the syngas can be conditioned to serve as feed for any syngas-to-syncrude conversion technology. Fischer–Tropsch synthesis is not the only possible technology for the conversion of syngas into a synthetic crude oil (syncrude), but together with syngas-to-methanol conversion [1], Fischer–Tropsch synthesis is industrially the most relevant. This book deals with the third step in Figure 1.1, namely, the refining of the syncrude into final marketable products, and it specifically deals with the refining of Fischer–Tropsch syncrude as the title suggests. Since methanol is also a product of Fischer–Tropsch synthesis, the refining of methanol as syncrude component is covered too. The representation in Figure 1.1 does not do justice to the complexity of indirect liquefaction. Whole texts have been devoted to aspects of the indirect liquefaction process, such as coal gasification [2, 3], Fischer–Tropsch technology [4–7], and the catalysis of Fischer–Tropsch syncrude refining [8]. This chapter provides only an overview of Fischer–Tropsch facilities. It shows how the component parts are linked together and why they are interdependent. In subsequent chapters, each one of the topics is revisited in more depth, in order to present the detail that is necessary to comprehensively deal with the topic of this book, namely, Fischer–Tropsch refining. Fischer–Tropsch Refining, First Edition. Arno de Klerk.  2011 Wiley-VCH Verlag GmbH & Co. KGaA. Published 2011 by Wiley-VCH Verlag GmbH & Co. KGaA.

4

1 Fischer–Tropsch Facilities at a Glance

Feed

Feed-to-syngas

Coal Gasification Natural gas Reforming Biomass Partial oxidation Waste Oil shale Oil sands Figure 1.1

Syngas-to-syncrude

Syncrude-to-product

Products

Fischer-Tropsch Syngas-to-methanol Kölbel Engelhardt Syngas-to-oxygenates

Refinery processes

Fuels Chemicals

Overall indirect liquefaction process for feed-to-liquids (XTL) conversion.

1.2 Feed-to-Syngas Conversion

Feed-to-syngas conversion is an energy-intensive operation and also the most expensive step in indirect liquefaction. Many of the advantages that are related to the feed-to-syngas conversion step do not depend on subsequent processing. It is these advantages that make indirect liquefaction attractive, despite its poorer energy efficiency than direct liquefaction [9–11]. 1) Feed diversity. One of the major advantages of indirect liquefaction over direct liquefaction is the wide selection of feed materials that can be used. In addition to coal and natural gas, it is possible to employ almost any other carbon source as feed material. The conversion of biomass and waste are attractive concepts, since biomass represents a renewable source of energy and waste conversion represents the beneficial reuse of discarded material. Waste products that can be considered include domestic and industrial waste, for example, discarded plastic containers, old tires, and asphalthenes from carbon rejection processes. However, feed diversity is not the same as feed flexibility. The design of the feed-to-syngas conversion step has to be based on a specific feed slate and it generally has little feed flexibility beyond its designed range of feed compositions. 2) Mineral rejection. Indirect liquefaction has the inherent ability to process and separate carbon matter from mineral matter in mineral-containing carbon sources. Oil shales, peat, coal, and oil sands are all mineral-containing carbon sources. Such solid feed materials are typically converted in gasifiers to produce syngas. Once the carbon in these carbon sources has been oxidized to carbon monoxide, separation of the gaseous products from the mineral matter is easily achieved. The physical state of the rejected mineral matter depends on the gasification technology that was employed and it may be a dry ash or a slag. 3) Heteroatom removal. Carbon-containing feed material usually contains other elements in addition to carbon and hydrogen. When the feed is converted into a raw synthesis gas, heteroatoms in the feed are also converted into gaseous compounds, such as hydrogen sulfide (H2 S), carbonyl sulfide (COS), and ammonia (NH3 ). When the raw synthesis gas is purified, these heteroatom-containing compounds are removed to produce a pure synthesis gas, consisting of only carbon monoxide and hydrogen. With the exception of oxygen, all other heteroatoms are therefore removed during syngas purification. The removal of heteroatoms benefits the syncrude refinery, since the syncrude now only contains Cx Hy Oz -compounds.

1.2 Feed-to-Syngas Conversion

1.2.1 Feed Logistics and Feed Preparation

It is convenient to look at the carbon-containing feed merely as a feed process stream. In the case of natural gas feed that is already available from a pipeline supply, this may be a good approximation, but it is an oversimplification in most other cases. The steps involved in obtaining and preparing feed for indirect liquefaction are more complex (Figure 1.2). The carbon source is not always concentrated, as it is in the case of a natural nonrenewable resource such as coal. Biomass-derived feed is not concentrated at a single point of origin. Biomass has a low energy density and the feed logistics involved in collecting and transporting the biomass from its origin to the indirect liquefaction facility significantly adds to the cost and complexity of the process. Feed pretreatment and logistics are generally costlier than the direct operating cost of indirect liquefaction to produce Fischer–Tropsch syncrude. It can account for up to a third of the total production cost of the whole facility [12]. For natural gas, the feed logistics may be a significant factor in deciding whether to invest in indirect liquefaction or not. Natural gas can be directly distributed by pipeline as fuel gas, or it can be compressed and distributed as liquefied natural gas (LNG). All raw materials, including natural gas, require some form of feed pretreatment before they are suitable for conversion into syngas. The nature of the pretreatment is directly linked to the method of syngas production. It is prudent to select the syngas production technology with this in mind, since feed pretreatment can be a significant cost component. 1.2.2 Syngas Production

All syngas production technologies involve some form of partial oxidation (Chapter 3). It is convenient to consider the production of syngas from gaseous and solid carbon sources separately. Irrespective of the feed, the syngas production technology must be compatible with the feed and it should ideally be selected to meet the syngas requirements of the syngas-to-syncrude conversion technology. As rule of thumb, one aims for a H2 :CO ratio of around 2 in the syngas. The exact H2 :CO ratio that is required depends on the Fischer–Tropsch technology and the design of Fischer–Tropsch gas loop. The H2 :CO ratio can also be adjusted during syngas conditioning (Section 1.2.3).

Resource

Recovery

Transport

Feed preparation

Coal Natural gas Biomass Waste Oil shale Oil sands

Mining Drilling Harvesting Collection

Railroad Pipeline Trucking Shipping

Crushing Conditioning Slurrying Compacting Dewatering Milling Sieving

Figure 1.2

Feed logistics and preparation for indirect liquefaction.

Feed

5

6

1 Fischer–Tropsch Facilities at a Glance

Natural gas is already gaseous and it has no associated mineral matter to contend with. The two main conversion technologies for feed-to-syngas conversion are steam reforming and adiabatic oxidative reforming. Steam reforming is the dominant process for hydrogen production in refineries, and it is able to convert hydrocarbon feed materials ranging from natural gas to heavy naphtha. A steam reformer is essentially a reactor that consists of a fired heater with catalyst-filled tubes placed in the radiant zone of the fired heater. The heat needed for reforming, which is an endothermic conversion, is externally supplied by burning a fuel in the fired heater. The feed consists of a mixture of hydrocarbons and steam (H2 O). The syngas thus produced has a high H2 :CO ratio; a H2 :CO > 2 is typical. When syngas is prepared for Fischer–Tropsch synthesis, steam can be partially substituted by carbon dioxide (CO2 ) to lower the H2 :CO ratio in the syngas [13]. Adiabatic oxidative reforming produces a syngas with a lower H2 :CO ratio; a H2 :CO ratio in the range 1.6–1.9 is typical. The feed consists of a methane-rich hydrocarbon source, an oxidant (air or oxygen), and, in some instances, steam. The heat needed for reforming is directly supplied by combustion of part of the feed. This allows for a more compact design than a steam reformer. However, in the case of oxygen-fired reformers, it has the disadvantage of requiring an associated air separation unit (ASU), which is not required by a steam reformer. Solid feed materials have to be gasified in order to produce syngas. Gasification processes can be classified in terms of gas outlet temperature or reactor properties. These two classifications go hand in hand (Table 1.1) [3]. Low-temperature gasification typically employs a moving bed and has a gas outlet temperature of 425–650 ◦ C. The carbon-containing feed is fed from the top and the oxidizing gas is fed at the bottom. In this countercurrent flow arrangement, the hot ash at the bottom of the bed preheats the oxidizing gas before it enters the gasification zone. Gasification takes place in the middle of the bed. As the hot syngas produced in the gasification zone moves upward through the bed, it preheats and devolatilizes the carbon-containing feed at the top of the bed. Much of the heat recovery therefore takes place in the gasifier. Owing to the lower temperature in the top layer of the gasifier, pyrolysis liquids are coproduced during low-temperature gasification. This is an important distinguishing feature of low-temperature gasification that has implications for downstream refining. The refinery receives not only syncrude from the syngas-to-syncrude Table 1.1

Classification of gasification technologies for feed-to-syngas conversion and their main attributes.

Attribute

Temperature of syngas (◦ C) Reactor technology Particle size of feed (mm) Oxidant demand Steam demand Pyrolysis products in gas H2 :CO ratio in syngas

Gasification technology Low temperature

Medium temperature

High temperature

425–650 Moving bed 6–50 Low High Yes >2 : 1 to aromatization [59]. The relative reaction rates of alkenes and alkanes were also quantitatively reported for H-ZSM-5 (Table 21.4) [23]. Although this data is for a low-activity catalyst, it illustrates the effect of carbon number and compound class on relative conversion rates well. Catalytic cracking can therefore be applied to naphtha range alkenes, but converting naphtha range alkanes requires more severe conditions. Naphtha range alkanes can be converted by thermal cracking, but make poor catalytic cracking feed material. 5) The ease of cracking increases with the heaviness of the feed material. This can be seen from data in Table 21.4. Applying FCC with wax is therefore very different to FCC of naphtha. Naphtha range alkanes are more refractory and require very severe conditions to be converted. Hydrogen rejection to produce naphtha range alkanes effectively transforms those molecules into inert species.

21.4 Catalytic Cracking Cracking rate constants for naphtha range alkenes and alkanes over a low-activity H-ZSM-5 catalyst at 510 Ž C and 1.3 kPa hydrocarbon partial pressure. The catalyst and conditions were selected to avoid bimolecular reactions and diffusion effects.

Table 21.4

Carbon number

C5 C6 C7 C8

Rate constant (s−1 ) Alkene

Alkane

9.5 231 1823 5732

0.30 0.84 1.49 2.25

Rate ratio of alkene to alkane conversion

32 275 1220 2550

21.4.1 Catalysis

The FCC of Fischer–Tropsch waxes have been investigated over amorphous silica–alumina (ASA) and the zeolites Beta (BEA), H-Y (FAU), and H-ZSM-5 (MFI). Differences in the activity of various cracking catalysts are masked by the high reactivity of Fischer–Tropsch wax as feed material. High conversion was obtained even at very low catalyst to wax ratio (Table 21.5) [53]. Irrespective of the catalyst employed for FCC of wax, it was found that for each catalyst the conversion and product distribution was insensitive to the operating severity and the condition of the catalyst (i.e., catalyst age) [51, 53]. The coke make was also consistently low (221 Ž C Coke Gasoline properties RON MON

H-Y

H-Beta

H-ZSM-5

0.6 7.4 0.8 7.4 5.8 3.7 4.0 7.7 3.6 41.7 17.0 0.3

0.6 8.9 0.9 8.3 9.4 3.6 4.3 9.2 2.2 35.8 16.8 0.2

1.5 17.5 2.7 15.1 12.3 3.6 4.1 9.8 2.0 15.3 16.2 0.1

85.2 76.2

84.4 74.6

84.4 76.0

observations can be made dependent on and independent of the catalyst type on the catalytic cracking of Fischer–Tropsch wax: 1) All catalysts seem to ‘‘nibble’’ bits off the long-chain wax molecules [49]. This is understandable, because it would be unlikely for a wax molecule to enter into the catalyst without encountering an acid site on its way in. This has two important implications. The first is that for long-chain alkanes the cracking rate will be chain length independent, as was indeed experimentally observed [49]. The second implication is that the cracking probability is not equal along the carbon chain. 2) The carbon number distribution of the product from H-Y with its wider pores is mainly C3 –C10 , whereas the product distribution from H-ZSM-5 with its narrower pores is predominantly C3 –C6 . It is less likely for a wax molecule on its way into the wider pore zeolite catalyst to immediately encounter an acid site, and the ‘‘nibbles’’ from the wider pore zeolite are larger. The differences in product carbon number distribution reflect the different probabilities of being protoned as the wax molecule enters the zeolite. A dramatic demonstration of this effect can be seen from polyethylene cracking over H-ZSM-5 at 400 Ž C, which yielded C3 –C4 hydrocarbons as main product [61]. 3) The catalytic cracking products at around 80% wax conversion (Table 21.6) are mostly in the C3 –C12 carbon number range. Little or no H2 and C1 –C2 hydrocarbons are formed, indicating that the contribution of thermal cracking and protolysis were limited. 4) The ratio of branched to linear hydrocarbons in the >220 Ž C boiling material increased with increasing conversion over H-ZSM-5, while it decreased over H-Y [50]. This is not due to skeletal isomerization of the wax, but to reactant shape selectivity. It is more difficult for

21.4 Catalytic Cracking

5)

6)

7)

8)

9)

10)

branched alkanes in the feed to enter the smaller pores of H-ZSM-5 than the n-alkanes. The n-alkanes were thus more readily converted. The wider pores of H-Y zeolite did not impose the same diffusion restriction on branched alkanes and there were no reactant shape selectivity effects. Since branched alkanes intrinsically have a higher cracking rate than n-alkanes, the branched material was converted at a higher rate over H-Y than the n-alkanes. The pore-constrained geometry of H-ZSM-5 is also responsible for transition-state selectivity (Section 19.3.2). This caused all but the lightest products produced by catalytic cracking to be less branched than that obtained by wider pore acid catalysts. The effect of transition-state selectivity is not apparent in the C4 –C5 fraction. The position of branching affected the cracking conversion rate of branched alkanes over H-ZSM-5, which was not the case with H-Y. In H-ZSM-5, the 2-methyl and 3-methyl branched alkanes were more readily converted than alkanes with methyl branching closer to the center [50]. This is also a reactant shape selectivity effect due to the more pore-constrained geometry of H-ZSM-5 compared to H-Y. The octane number of the naphtha fraction is generally low. The cracking of Fischer–Tropsch wax over H-ZSM-5, H-Beta, and H-Y catalysts mostly resulted in a RON in the range 84–88 and a MON in the range 74–76 [53]. The rate of formation of multinuclear aromatics to produce coke is lower on H-ZSM-5 than on H-Y. This is especially apparent when looking at initial selectivity. The limited formation of coke is a result of the transition-state selectivity imposed by the pore constraints in H-ZSM-5, which hinders repeated cyclization necessary for the formation of multinuclear aromatics [62]. Although the FCC of wax did not show a strong dependence on the acidity of the catalysts [53], acid strength as well as acid site density has an effect on cracking rate and coking rate [63]. These effects will be more apparent during the cracking of naphtha range alkanes that are more refractory. Hydrothermal dealumination of catalytic cracking catalysts by steaming takes place during reaction and regeneration [64]. Oxygenates will be converted by FCC to, among other products, water. The water in itself is not expected to have a significant impact on the rate of hydrothermal dealumination. However, it has been postulated that dealumination caused by oxygenate dehydration directly on the catalytic surface may be considerably higher than the rate of dealumination by steaming [65]. Since the water is produced as an adsorbed reaction intermediate on an acidic alumina site, desorption may occur, but it may also lead to bond formation and dealumination.

21.4.2 Syncrude Processing Technology

Processing hydrogen-rich Fischer–Tropsch syncrude in an FCC unit requires some modifications that deviate from standard practice with residue feed materials. Applying FCC technology with Fischer–Tropsch syncrude requires significant modifications of the technology and in different ways for different feed and operating conditions:

425

426

21 Cracking

1) Fischer–Tropsch waxes are readily converted, and high conversion can be achieved at low catalyst to wax ratio (Table 21.5). Since cracking is an endothermic reaction, there is a practical lower limit to the catalyst to wax ratio from a heat balance perspective and one may want to consider increasing the addition of inert material as heat carrier only. Decreasing the catalyst to wax ratio without substituting the catalyst with inert material to maintain a similar particle size distribution and solids to wax ratio will also lead to scale-up issues. Dudkovi´c and coworkers experimentally demonstrated that the solids to fluid ratio in the riser affects the axial velocity profile [66]. As the mass flux is decreased, the degree of back-mixing is increased, which implies that a fraction of the catalyst particles spend a much longer time in the riser. At a low catalyst to wax ratio, this may lead to an even lower effective catalyst to wax ratio and a broad distribution of coke content on the catalyst. This will affect both cracking performance and the performance of the regenerator. When hydrodynamics is taken into consideration, it recommended that wax FCC applications employ higher catalyst to wax ratios than suggested by the conversion requirements. 2) If the operation of the FCC unit is not adjusted to obtain sufficient coke laydown on the cracking catalyst, it will be necessary to provide an additional source of heat in the regenerator section. With a hydrogen-rich feed, it is unlikely that sufficient coke can in fact be formed on the catalyst. During the extensive test work conducted at Amoco [53], a 1% coke yield was seldom exceeded. 3) Introducing additional fuel in the regenerator may seem a simple modification of the technology, but it is not. Coke has very different combustion characteristics to that of liquid fuels, even a very heavy fuel. Achieving complete catalyst regeneration and avoiding methane formation due to thermal cracking of the liquid fuel in the regenerator are easier said than done. Introducing a solid carbonaceous fuel is less convenient, but in the long run it may lead to more stable regenerator operation. 4) High-temperature FCC runs the risk of an increased contribution from thermal cracking. Corma and coworkers have shown that an increase in thermal cracking during FCC drastically lowers the light alkene yield [67]. This is very detrimental to petrochemical applications of FCC with Fischer–Tropsch syncrude. It is also detrimental to fuels applications, since the naphtha range product will have an even lower octane number despite the increase in aromatics content. 5) Employing FCC with paraffinic naphtha feed results in a naphtha range product with lower octane number than that obtained by FCC of wax. With wax, the unhydrogenated naphtha product typically had an RON of 84–88 and MON of 74–76, but with naphtha feed the product had an RON of 74–79 and MON of 65–70 [53]. These values were obtained by cracking in the temperature range 470–520 Ž C, and increasing the temperature had little effect on the quality of the naphtha. 6) Naphtha range alkanes are difficult to crack, and even at very high temperature the conversion of Fischer–Tropsch naphtha will be strongly dependent on the alkene and oxygenate content of the naphtha feed. Aromatization at very high temperature may increase the octane number of the naphtha fraction somewhat, but typically at the expense of alkene conversion into alkanes. There is consequently a trade-off between petrochemical and fuel production by FCC of syncrude. 7) In petrochemical applications, FCC at severe conditions may be contemplated. If such operation falls outside the temperature range of typical FCC operation (Table 21.1), care

21.5 Hydrocracking

8)

9)

10)

11)

12)

must be taken to confirm the higher temperature characteristics of the equipment. Both physical and chemical aspects need to be considered. The thermal expansion coefficients and strength of the metals and refractory bricks developed for typical FCC operation must be evaluated for higher temperature operation. A mismatch in thermal expansion or mechanical strength can lead to problems. The activity of metal surfaces for dehydrogenation and coking should also be evaluated. Oxygenates may also undergo dehydrogenation and hydrogenation reactions [68]. Conducting FCC at high temperature, where thermal cracking becomes significant beyond the initial thermal shock at the bottom of the riser, affects reaction engineering considerably. When the contribution of thermal cracking cannot be ignored, cracking may continue after the riser and disengagement of the catalyst, because thermal cracking does not require a catalyst. The total residence time before product cooling quenches free radical reactions now becomes critical. Until the product is quenched, free radical reactions may continue. The time–temperature profile is likewise critical. As the product is cooled down, it passes through the temperature region where thermal oligomerization (Section 19.3.6) takes place. Radical recombination reactions may lead to the formation of heavy oils and carbonaceous deposits when the product spends time in the 300–450 Ž C temperature region. High-temperature operation will also lead to changes in product selectivity. Some products, such as benzene, dienes, CH4 , and H2 , are more abundant in products from thermal cracking than in products from conventional FCC. This not only affects downstream refining but also increases the dry gas flow from the FCC. The impact of increased benzene production on the refining requirements to meet motor-gasoline specifications is self-evident. Additionally, oxygenates produce CO and CO2 . Feed preheating for high-temperature FCC is also challenging. Some thermal cracking of the syncrude can be initiated at temperatures above 300–320 Ž C. If linear velocities are too low, heavy products will be deposited on the exchanger surfaces, causing fouling problems. This is especially likely with alkene- and oxygenate-rich syncrude feeds. Oxygenates present in the syncrude may be more aggressive to the cracking catalyst than steam. Hydrothermal dealumination by oxygenates may lead to a higher catalyst consumption rate. Although high oxygenate conversion can be achieved in an FCC unit, the product may contain some carboxylic acids. Downstream processing equipment must be designed to handle acidic products.

21.5 Hydrocracking

In Fischer–Tropsch refining, hydrocracking has emerged as an important conversion technology for the upgrading of LTFT waxes in gas-to-liquids facilities (Chapters 11 and 12). It is industrially employed in a number of commercial facilities. Hydrocracking of LTFT waxes is different to typical crude oil hydrocracking technology in a number of respects (Table 16.2) [4, 69]. Fischer–Tropsch wax hydrocracking requires milder conditions than crude oil hydrocracking, and on account of its low heteroatom

427

428

21 Cracking

and aromatics content, LTFT wax hydrocracking consumes little hydrogen and is almost isothermal. HTFT residues, on the other hand, more closely resemble aromatic crude oil fractions, albeit without sulfur- and nitrogen-containing compounds. One should therefore not confuse the mild processing requirements of LTFT wax hydrocracking with the more severe requirements for HTFT residue hydrocracking. The inclusion of a hydrocracker in a Fischer–Tropsch refinery is typically considered for the following applications (Section 16.5.2): 1)

2)

3)

4)

5)

The use of wax hydrocracking to produce distillate blend stock is the best known and industrially the most practised application of hydrocracking in Fischer–Tropsch refining. The distillate that can be produced from hydrocracking LTFT wax has a low aromatic content (70), and low density (51) specification and a minimum density (820–845 kg·m−3 ) specification. Any two of these criteria can be met without too much refining effort. For example, it is possible to produce a distillate in high yield with adequate cetane number, or with adequate cetane number and density, but not meeting all three criteria simultaneously. The refining of HTFT syncrude to on-specification diesel fuel is a case in point. With proper hydroprocessing, HTFT syncrude can be converted into a diesel fuel of adequate cetane number and adequate density, but the overall diesel fuel yield is low in comparison to the other fuel types. The point is also illustrated by the hydrocracking of LTFT wax. LTFT syncrude can be converted in high yield to a high-cetane-number distillate, but the distillate has a low density (∼780 kg·m−3 ).

563

27 Diesel Fuel Refining

120

n -Alkanes 1-Alkenes n -Alkylbenzenes Branched alkanes Cycloalkanes

100 Cetane number

564

80 60 40 20 0 720

Figure 27.3

740

760

780 800 820 Density at 20 °C (kg m−3)

840

860

880

Cetane–density relationship of various compounds in the distillate boiling range.

There is a trade-off between cetane number and density for different compound classes (Figure 27.3). The value of cycloalkanes as constituent of diesel fuel is clear, since these are the only compounds that readily meet cetane number and density specifications. The cycloalkanes also have good cold-flow properties. An important synergistic effect is that both cetane number and density generally increase with carbon number (boiling point) within each compound class. Coproducing jet fuel in a Fischer–Tropsch refinery is therefore helpful in meeting both cetane number and density specifications of diesel fuel, albeit at the expense of yield. The loss of yield is anticipated by the density–cetane–yield triangle. Overcoming the density–cetane–yield triangle is central to the production of on-specification diesel fuel in a Fischer–Tropsch refinery. In countries where the diesel fuel does not have a minimum density requirement, or has a lower minimum density requirement, it is much easier to produce on-specification diesel fuel because only two of the criteria have to be met. Unfortunately, it has to be conceded that on a molecular level Fischer–Tropsch syncrude is unsuitable for the production of EN590:2004-type diesel fuel in high yield. Ways in which this deficiency can be overcome are explored in Section 27.3.4.

27.3 Decisions Affecting Diesel Fuel Refining

There are design decisions that affect all transportation fuels. Many of the important points discussed with reference to motor-gasoline production (Section 25.3) are also applicable to diesel fuel production. The same is true of the discussion on jet fuel production (Section 26.3). In order to avoid duplication, reference is made to all the topics that are relevant, but only the aspects that are specific to diesel fuel production are expanded upon: 1) Chemicals coproduction (Section 25.3.1).

27.3 Decisions Affecting Diesel Fuel Refining

2) 3) 4) 5)

Fate of the C2 –C4 hydrocarbons (Sections 25.3.2 and 26.3.1). Fate of the residue and wax (Sections 25.3.3 and 26.3.2). Fate of the aqueous product (Section 25.3.4). Co-refining (Section 25.3.7).

27.3.1 Fate of C2 –C4 Hydrocarbons

Oligomerization is an important technology to increase the yield of distillate from the C10 and lighter syncrude. This includes the C2 –C4 hydrocarbons. However, unlike jet fuel, a high degree of branching is not desirable in diesel fuel. Oligomerization technologies that do not employ pore-constraining catalysts are likely to produce highly branched oligomers from the light alkenes. Highly branched distillates will have excellent cold-flow properties, but correspondingly low cetane numbers. Oligomerization with H-ZSM-5-based technology is recommended to convert C3 –C4 alkenes into distillate. The MFI-type zeolite is pore constrained and yields a distillate with adequate cetane number despite the light alkene feed material employed (Table 19.4). Ethene is more difficult to oligomerize over solid acid catalysts, but can in principle produce a linear product with high cetane number, not unlike the heavier alkenes present in the straight-run syncrude. Unfortunately, there is no convenient technology for ethene oligomerization to distillate specifically; such technologies are all aimed at n-1-alkene petrochemical production [15]. It makes little sense then to hydrogenate the material to distillate if it is one of the few products that attracted Fischer–Tropsch-specific technology development (Section 23.2). 27.3.2 Fate of the Residue and Wax

Choosing between the different cracking technologies for converting LTFT wax to distillate is somewhat academic. Fluid catalytic cracking does not yield a significant distillate (light cycle oil) fraction from wax (Table 21.6), whereas hydrocracking does (Figure 21.8). Thermal cracking has been compared to hydrocracking for distillate production, and it was found to be less efficient although the product is more linear [16]. Hydrocracking is therefore the obvious choice for producing distillate from LTFT wax. The same arguments apply to HTFT syncrude. The HTFT residue can be directly converted into on-specification diesel fuel by hydrocracking [10]. The residue is a small fraction of the total syncrude and, although it can easily be refined to diesel fuel, it does not contribute much to the overall refining of HTFT syncrude. 27.3.3 Fate of the Aqueous Product

The C3 and heavier oxygenates recovered from the Fischer–Tropsch aqueous product are employed as diesel fuel extenders in conjunction with Fischer–Tropsch-derived distillate (Table 10.4) [12]. The carbonyls are first partially hydrogenated to produce alcohols, and the alcohol mixture is then blended with the diesel fuel. These alcohols are mainly in the C3 –C5 range. The blending

565

566

27 Diesel Fuel Refining

of ethanol and ethanol–methanol mixtures with diesel fuel has also been reported [17], although not specifically with Fischer–Tropsch distillates. An alternative pathway involves etherification. The C5 and heavier alcohols can be etherified to produce linear fuel ethers [13, 18], but C3 –C4 alcohols are considered too light for this purpose. Etherification is better suited for the refining of oil-phase oxygenates. 27.3.4 Technology Selection

The technology selection for diesel fuel refining is very dependent on whether the diesel fuel must conform to a minimum density specification or not. These two cases are considered separately. When there is no restriction placed on the minimum density of the diesel fuel, hydrocracking, oligomerization, and hydrotreating are the only three conversion units needed to refine syncrude to diesel fuel. The conversion to distillate can be performed as shown in Figure 27.2. In more practical terms, the flow diagram should include a hydrotreater to improve the storage stability and increase the cetane number of the straight-run distillate range products, as well as the distillate obtained from alkene oligomerization. The technology selection is consequently straightforward (Figure 27.4). In countries where the cold-flow requirements for diesel fuel are arduous, it may be necessary to perform mild hydroisomerization on the straight-run distillate. When there is a restriction on the minimum allowable density of the diesel fuel, the technology selection must overcome the limitations described as the Fischer–Tropsch density–cetane–yield triangle (Section 27.2.4). A too low density of diesel fuel is not a problem encountered in crude oil refining; the opposite is often the case. Consequently, there are no refining technologies that have been developed specifically to overcome this problem. Blending and co-refining (Section 27.3.5) with materials such as crude oil and coal-derived liquids are obvious solutions to this problem. These materials are rich in cyclic hydrocarbons that can be refined to cycloalkane-rich distillates with adequate density and cetane number. The cetane number and density will also increase with increasing jet fuel production, albeit with an associated loss in diesel fuel yield. C3 C4

Oligomerization

C5 − C10 C11− C22 >C22

Alkene hydrogenation

Alkanes

Hydrotreating

Alkanes

Mild hydroisomerization

Alkanes

Hydrocracking

Figure 27.4 Technology selection for the refining of syncrude to diesel fuel when there is no minimum diesel density requirement.

Alkanes

27.3 Decisions Affecting Diesel Fuel Refining

When it is important for the refinery design to be stand-alone and independent of external blending materials, technologies and refining strategies must be selected to deal with the density–cetane–yield triangle. The following technology-based strategies were proposed to increase distillate density without undermining the cetane number of the distillate [8]: 1) Cycloalkane synthesis. The synthesis of cycloalkanes by dehydrocyclization of alkanes is one of the steps in catalytic reforming (Chapter 22). The driving force for further catalytic dehydrogenation is thermodynamic, and cycloalkanes can in principle be recovered as an intermediate product. Cycloalkanes may be recovered as the main product from conversion in the operating range 250–400 ◦ C; aromatics become the dominant product at higher temperatures [19]. Higher temperature operation is possible, but only when the conversion per pass is limited to allow the recovery of cycloalkanes as intermediate products. 2) Linear alkyl benzene(LAB) synthesis. The technology for LAB synthesis by aromatic alkylation (Chapter 20) is well established [20]. Since LABs are large-volume commodity petrochemicals, it is doubtful whether it would make sense to synthesize LAB and then use it as a diesel fuel additive. 3) Alcohol refining. It has been noted that alcohols can be used as diesel fuel extenders (Section 27.3.3). Heavy alcohols can help increase the density, but the alcohols obtained from the aqueous product are too light to have a beneficial effect. As the chain length of the alcohol increases, cold flow becomes an issue. This problem can be overcome by turning the alcohols into linear fuel ethers, but the distillate range fuel ethers typically have densities of less than 810 kg·m−3 (Table 17.1). 4) Autoxidation of distillate. When distillate range material is autoxidized (Section 23.3), the incorporation of an oxygenate functionality into the hydrocarbons results in an increase in the density [21]. There is an accompanying increase in cetane number and lubricity too, but a decrease in storage stability. 5) Oligomerization technology selection. Oligomerization over an amorphous silica–alumina catalyst results in a distillate with much higher density (Table 19.5) on account of some cycloalkane formation. This comes at the expense of a lower cetane number, invoking the spectre of the density–cetane–yield triangle. 27.3.5 Co-refining

Blending and co-refining of non-Fischer–Tropsch-derived material is by far the easiest way to overcome the limitation described by the density–cetane–yield triangle. It also addresses some of the other concerns related to hydroprocessed LTFT distillate specifically, namely, elastomer incompatibility due to the lack of aromatics and polar compounds [22], emissions produced on account of the too high cetane number that results in combustion before complete air–fuel mixing [23], and the poorer volumetric fuel economy due to the low fuel density. Crude-oil-derived diesel fuel is the most readily available blending stock. In the past, such a blend would have been beneficial for the crude-oil-derived diesel fuel, because the sulfur-free Fischer–Tropsch distillate would reduce the sulfur content significantly. At present many crude-oil-derived diesel fuels contain less than 10 µg·g−1 sulfur and there is little benefit in this regard when mixed with Fischer–Tropsch distillate. Fischer–Tropsch distillate may still be

567

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27 Diesel Fuel Refining

Natural gas

Gas reformer

H2 Gasifier

Oxygenates

Fischer− Tropsch synthesis

Syngas purification and conditioning

Coal biomass waste

Purge

Tail gas

Wastewater

Syncrude Pyrolysis oil Fuel gas

Naphtha

LPG Crude oil

Distillate

REFINERY

ADU Vacuum gas oil

Gasoline Diesel fuel Lubricant base oil

VDU Vacuum residue

Figure 27.5

Chemicals

Integrated crude oil and Fischer–Tropsch refinery.

beneficial in mixtures with heavy crude-oil-derived diesel fuels in order to reduce the density. By doing so, the lack of adequate density in the Fischer–Tropsch distillate is synergistically exploited. Other benefits of blends between crude-oil-derived diesel fuel and LTFT distillate have also been reported [24]. The advantage of co-refining LTFT syncrude with crude oil has been outlined by Gregor [25]. By coprocessing the vacuum gas oil and Fischer–Tropsch wax in a hydrocracker, a better quality distillate can be obtained from the combined feed. Other advantages that are not directly related to diesel fuel have also been noted. A Fischer–Tropsch facility that is integrated with a crude oil refinery has many potential synergies (Figure 27.5). Coal liquids offer similar advantages to crude-oil-derived diesel fuel for blending with Fischer–Tropsch distillates. Blends of coal-liquid-derived distillates and LTFT distillates were shown to have improved fuel economy and material compatibility [26]. Historically, the blending of coal liquids and LTFT distillates was common practice for the production of diesel fuel [1, 2]. Two industrial Fischer–Tropsch facilities were designed to co-refine coal liquids and syncrude (Chapters 8 and 9), and blends of HTFT distillate and coal distillate are marketed commercially as diesel fuel in South Africa [27–29]. The addition of biofuel in the form of FAME has some benefit, although it would be necessary to address the storage stability issues reported in the literature [7]. The FAME that are derived from different oils all have high densities and adequate cetane numbers (Table 27.2) [30]. By blending FAME with Fischer–Tropsch distillate, the density can be increased without undermining the cetane number of the blend.

27.3 Decisions Affecting Diesel Fuel Refining Selected properties of fatty acid methyl esters (FAME) prepared from different oils that are important for diesel fuel.

Table 27.2

FAME source

Sunflower oil Corn oil Used frying oil Olive oil

Density at 20 ◦ C (kg·m –3 ) 885.3 885.8 882.9 880.1

Cetane number

57.5 65 59 61

Viscosity at 40 ◦ C (cSt) 4.4 4.5 4.5 4.7

Cold filter plugging point (◦ C) –2 –7 –4 –6

The co-refining of HTFT and LTFT syncrudes is not a new concept, and it was practised on an industrial scale for many decades (Chapter 8). The combined refining of HTFT and LTFT syncrude has specific advantages for diesel fuel production and was considered for the proposed Mafutha coal-to-liquids project [31]. The HTFT syncrude fulfills the same purpose as crude oil as a source of an aromatic heavy fraction. However, due to the limited volume of distillate and heavier material in HTFT syncrude, the yield benefit is less than the yield benefit that can be obtained by co-refining a heavier feed material, such as crude oil. 27.3.6 Dealing with the Density–Cetane–Yield Triangle

There are no conventional refining pathways to produce diesel fuel in high yield from Fischer–Tropsch syncrude while meeting both the density and cetane number specifications. In order to overcome the limitations of the density–cetane–yield triangle, some less conventional refining approaches, product blending, and co-refining were explored (Sections 27.3.4 and 27.3.5). Of these options, blending is by far the easiest solution. The question still remains, what yield of on-specification diesel fuel can be obtained by conventional refining of syncrude? The refining challenge can be outlined as follows [32]: Most conventional refining technologies to produce distillate from syncrude produce either distillate high in density and low in cetane number, like aromatics, or distillate low in density and high in cetane number, like alkanes. It is this trade-off that gives rise to the density–cetane–yield triangle. Refinery design to enable any further increase in the diesel fuel yield relies heavily on the lever rule (Figure 27.6). Two streams must be blended in such a way that the targeted minimum density (Equation 27.1) and minimum cetane number (Equation 27.2) can be met. ρ = y·ρ1 + (1 − y)·ρ2 = 820 kg·m−3

(27.1)

CN = z·CN1 + (1 − z)·CN2 = 51

(27.2)

The volume fraction y indicates the maximum amount of low-density, high-cetane-number material that can be blended with a high-density, low-cetane-number material. Conversely, the volume fraction z indicates the minimum amount of the low-density, high-cetane-number material that must be blended with the high-density, low-cetane-number material. If y ≥ z, then the blend will meet specifications, but if y < z, then the blend will not be able to meet specifications.

569

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27 Diesel Fuel Refining

∆1

(1 − y )

y

Low

r1

∆2 High

∆1

∆2

r

y=

r2

∆2

(1 − z)

z

Low

CN2

r2 − r r2 − r1

∆1 High

∆2

z=

CN

∆1

CN1

CN − CN2 CN1 − CN2

Figure 27.6 Application of the lever rule to the refining of diesel fuel from syncrude by balanced blending of a fuel that has a low density (ρ1 ) and high cetane number (CN1 ) with a fuel that has a high density (ρ2 ) and low cetane number (CN2 ).

When a conversion process produces a distillate that is either density- or cetane number constraining, a complementary conversion process must be selected that produces a distillate with the opposite constraint. The lever rule can then be applied to see whether the materials can be blended in a ratio that allows the diesel fuel specifications to be met. If two complementary processes can be found, the yield of diesel fuel can be increased. As mentioned before, this refining challenge becomes a mute point when the diesel fuel specification does not require a minimum density.

27.4 Diesel Fuel Refining from HTFT Syncrude

The distillate and residue fractions from HTFT syncrude can be hydroprocessed to produce an on-specification diesel fuel that meets both the minimum density and cetane number requirements (Table 27.1). The volume of diesel fuel that can be produced is equivalent to about 10% of the syncrude. This hydroprocessed diesel fuel forms the base blending material for further diesel fuel production. Any further increase in diesel fuel yield with conventional refining technology must employ the strategy outlined in Section 27.3.6. As mentioned before (Sections 25.4 and 26.4), there is a high carbon cost associated with the HTFT light hydrocarbons and the HTFT aqueous product. HTFT refinery design is therefore based on a closed gas loop with cryogenic C2 hydrocarbon recovery and methane recycle. 27.4.1 HTFT Diesel Fuel Design Case I

By employing only conventional refining technologies and FAME addition, it was shown that a refinery can be designed where about 25% of the liquid transportation fuel was on-specification EN590:2004 diesel fuel [32]. The hydroprocessed HTFT distillate and residue was employed as base blending material for the diesel fuel, and the yield was increased by blending hydrotreated

27.4 Diesel Fuel Refining from HTFT Syncrude Carbonyl hydrogenation

Aqueous product

Wastewater Fuel gas Gasoline Jet fuel Diesel

Aromatic alkylation

C2

LPG Gasoline

H-ZSM-5 oligomerization

C3 −C4

Alcohols

HTFT gas loop

Condensate C5 −C6 C5 Benzene

C6 −C8

Light oil

Alkene hydrogenation

Jet fuel Diesel

C5 Hydroisomerization

Gasoline

Nonacidic Pt/L reforming

H2 LPG Gasoline

>C6

Jet fuel

Hydrotreater

Decanted oil Hydrocracking >C11

Jet fuel Diesel

Figure 27.7 HTFT diesel fuel refinery design case I. The gas loop includes cryogenic C2 separation with methane recycle.

H-ZSM-5 oligomers and alkyl aromatics. The coproduction of jet fuel assisted the increase in diesel fuel yield, because it removed the lower density and lower cetane number fraction from the alkane-based distillate. An analogous design is presented (Figure 27.7). Diesel fuel production takes place by mild hydrocracking of the straight-run distillate and residue. Additional diesel fuel is produced by blending the distillate fraction from H-ZSM-5-based alkene oligomerization with alkyl aromatics. The H-ZSM-5-derived oligomer stream is the high-cetane, low-density material, and the alkyl aromatics stream is the low-cetane, high-density material. The alkyl aromatics employed were di- and triethylbenzenes obtained from benzene alkylation with ethene. These compounds have cetane numbers around 10 and densities around 870 kg·m−3 . Aromatic alkylation with ethene allows the ethene to be converted into a liquid product, and using ethene as alkylating agent is not necessarily the best choice from a diesel fuel perspective. Other technologies are necessary to meet the fuel specifications for motor-gasoline and jet fuel. The Fischer–Tropsch aqueous product is refined to alcohols by partial hydrogenation of the carbonyl compounds. The C3 and heavier alcohols can in principle be employed as diesel fuel extenders, and the ethanol can be used to improve the octane number of the motor-gasoline.

571

572

27 Diesel Fuel Refining

The amount of diesel fuel that can be produced depends mainly on the design and operation of the hydrocracker the fraction of light distillate that is employed for jet fuel production, and the target cetane number before additive addition. The impacts of these variables are shown (Table 27.3) as different operating scenarios of the Figure 27.7 refinery design: Table 27.3

Products from HTFT diesel fuel refinery design case I shown in Figure 27.7.

Description Product distribution (mass%)a H2 Fuel gas LPG Motor-gasoline Jet fuel Diesel fuel Petrochemicals produced Petrochemicals consumed Unrecovered organicsc Water to/from refining Liquid fuels (m3 ·t –1 )a LPG Motor-gasoline Jet fuel Diesel fuel Net productiona Liquid fuels (m3 ·t –1 ) Petrochemicals (kg·t –1 ) Fuel gas (kg·t –1 ) Motor-gasoline properties RON MON Density at 15 ◦ C (kg·m –3 ) Reid vapor pressure (kPa) Alkene content (vol%) Aromatic content (vol%) Benzene content (vol%) Oxygenate content (vol%) Jet fuel properties Density at 15 ◦ C (kg·m –3 ) Aromatic content (vol%) Diesel fuel properties Cetane number Density at 15 ◦ C (kg·m –3 )

Base case

0.0 7.3 7.3 36.9 21.1 15.2 6.5 0.0 5.1 0.5

Cetane number 47

0.2 7.0 7.2 38.2 12.5 22.7 6.5 0.0 5.1 0.5

FAME addition

0.0 7.3 7.3 36.9 19.0 18.2 6.5 −0.9b 5.1 0.5

0.133 0.493 0.270 0.186

0.132 0.510 0.160 0.277

0.133 0.493 0.245 0.222

1.082 65 73

1.079 65 72

1.093 56 73

95.1 87.7 749 60 17.1 33.3 0.3 0.0

95.2 87.8 750 59 16.5 32.5 0.3 0.0

95.1 87.7 749 60 17.1 33.3 0.3 0.0

778 22.3

779 24.2

776 22.1

51 820

47 820

51 820

a On a syncrude basis, excluding H , CO, CO , H O, and CH from HTFT synthesis (closed gas loop with cryogenic 2 2 2 4 separation). b Fatty acid methyl ester imported for blending. c Syncrude waste products (e.g., metal-containing fuel oil) and unrecoverable material (e.g., carboxylic acids in wastewater).

27.5 Diesel Fuel Refining from LTFT Syncrude

1) Base case design. The C3 and heavier alcohols from aqueous product refining were considered as petrochemicals and were not added to the diesel fuel. The hydrocracker design is based on a NiMo/SiO2 –Al2 O3 catalyst (Table 21.8) [10]. 2) Lower cetane number. Cetane number improvers (Section 15.4) can be employed to increase the cetane number of the final diesel fuel. Addition of 0.05 vol% of an appropriate cetane improver will increase the cetane number of the diesel fuel by around 3–4 points. This does not affect the cetane index. There is a minimum cetane index requirement too. The refinery design was evaluated at a cetane number of 47, which corresponds to a cetane index above the minimum requirement. The assumption is that the cetane number deficiency of 4 points can be rectified by the addition of a cetane improver. Lowering the cetane number requirement allows the diesel fuel yield to be improved at the expense of jet fuel production. 3) FAME addition. The addition of 5 vol% of FAME allows a slight increase in diesel fuel yield by cutting more jet fuel into the diesel fuel, because the FAME (Table 27.2) increases both the density and cetane number of the diesel fuel. All of the scenarios highlighted the constrained nature of diesel fuel production, as well as the negative impact that it has on the blending flexibility of other fuel types. HTFT syncrude is not well suited for diesel fuel production beyond that obtained from mild hydrocracking of the distillate and residue fractions.

27.5 Diesel Fuel Refining from LTFT Syncrude

Unlike HTFT syncrude, there is no refining pathway that directly yields on-specification diesel fuel when there is a minimum density specification (Table 27.1). Yet, a higher yield of on-specification diesel fuel and distillate can be refined from LTFT syncrude [32]. Since not all countries have a minimum density limitation on diesel fuel, two design cases will be considered. In the first design case (Section 27.5.1), the diesel fuel yield will be maximized without a minimum density constraint. This design case differs from the distillate refining strategy (Figure 27.2) in that all transportation fuels must meet specification. The diesel fuel in this case is not a distillate – it is a diesel fuel – with the caveat that there is no minimum density specification. The design is therefore not subject to the density–cetane–yield triangle. In the second design case (Section 27.5.2), the refinery design will produce as much diesel fuel as possible with a minimum density constraint. 27.5.1 LTFT Diesel Fuel Design Case I

Producing a diesel fuel with acceptable cetane number and cold-flow properties from LTFT syncrude is not difficult when diesel fuel density does not have to be considered. The design approach shown in Figure 27.2 will ensure that diesel fuel is produced in high yield. The need to produce transportation fuels that are all on-specification necessitates the inclusion of at least one conversion unit that is capable of producing aromatics. This has the added advantage of making the refinery design less reliant on the Fischer–Tropsch gas loop for its

573

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27 Diesel Fuel Refining Carbonyl hydrogenation

Aqueous

C3 – C4

Alcohols Wastewater LPG Gasoline

SPA alkylation oligomerization

C5

LTFT gas loop

Hydrotreater

Jet fuel

C5 hydroisomerization

Gasoline

Benzene

Hydrotreater

C6 – C8

Nonacidic Pt / L reforming

Hot and cold condensate

Hydrocracker

Wax

H2 Fuel gas Gasoline Jet fuel Diesel

Diesel

C23 and heavier

Figure 27.8 LTFT diesel fuel refinery design case I, which maximizes diesel fuel yield when there is no minimum density specification requirement. The gas loop includes C3 –C4 recovery with recycling of the C1 –C2 hydrocarbons in the tail gas.

hydrogen requirements. Excess aromatics can be added to the diesel fuel, since the paraffinic diesel fuel will have a high cetane number. The design of a diesel fuel refinery is quite straightforward, and it incorporates only hydrocracking, oligomerization, hydrotreating, aromatization (reforming), aromatic alkylation, and hydroisomerization units (Figure 27.8). The diesel fuel yield can be further increased by incorporating an oligomerization unit to convert the naphtha range alkenes into distillate (Figure 27.9). Oligomerization can be performed with an amorphous silica–alumina- or H-ZSM-5-based technology. In both variations of this design (Figures 27.8 and 27.9) the aqueous product is recovered and partially hydrogenated to produce alcohols. The alcohols may be added to the fuel as a diesel fuel extender. It is clear that, when there is no minimum density specification, a high diesel fuel yield can be obtained with both Fe-LTFT and Co-LTFT syncrudes (Table 27.4). The jet fuel has a much lower cetane number than the diesel fuel, but considering the high cetane number of the distillate, it is possible to include additional jet fuel into the diesel fuel. The constraining specification is the diesel fuel viscosity, which is lowered when additional kerosene range material is included in the diesel fuel.

27.5 Diesel Fuel Refining from LTFT Syncrude Products from LTFT diesel fuel refinery design case I, which produces diesel fuel without a minimum density specification requirement. The base case design is shown in Figure 27.8 and the design with an added naphtha oligomerization unit to increase diesel fuel yield is shown in Figure 27.9.

Table 27.4

Description

Figure 27.8 design Fe-LTFT

Product distribution (mass%)a H2 Fuel gas LPG Motor-gasoline Jet fuel Diesel fuel Petrochemicals produced Petrochemicals consumed Unrecovered organicsb Water to/from refining Liquid fuels (m3 ·t –1 )a LPG Motor-gasoline Jet fuel Diesel fuel Net productiona Liquid fuels (m3 ·t –1 ) Petrochemicals (kg·t –1 ) Fuel gas (kg·t –1 ) Motor-gasoline properties RON MON Density at 15 ◦ C (kg·m –3 ) Reid vapor pressure (kPa) Alkene content (vol%) Aromatic content (vol%) Benzene content (vol%) Oxygenate content (vol%) Jet fuel properties Density at 15 ◦ C (kg·m –3 ) Aromatic content (vol%) Diesel fuel properties Cetane number Density at 15 ◦ C (kg·m –3 )

−0.1 0.4 7.7 14.4 14.4 58.3 3.2 0.0 1.4 0.3

Co-LTFT

0.0 0.4 10.0 13.8 13.7 60.0 1.3 0.0 0.6 0.3

Figure 27.9 design Fe-LTFT

−0.2 0.1 7.3 10.7 6.3 71.0 3.2 0.0 1.4 0.2

Co-LTFT

−0.1 0.1 9.6 12.1 4.1 72.1 1.3 0.0 0.6 0.2

0.139 0.192 0.185 0.750

0.181 0.185 0.177 0.771

0.132 0.145 0.081 0.913

0.174 0.162 0.052 0.926

1.266 32 3

1.313 13 4

1.271 32 –1

1.315 13 0

95.4 87.3 752 42 15.0 30.4 0.4 0

95.3 87.8 746 60 7.1 31.1 0.4 0

98.4 90.5 742 59 16.1 32.9 0.3 0

98.8 90.5 746 59 17.7 33.8 0.3 0

776 17.7

777 17.7

775 19.0

779 17.1

72 778

72 778

69 778

69 778

a On a syncrude basis, excluding H , CO, CO , H O, and C –C hydrocarbons from LTFT synthesis (closed gas loop 2 2 2 1 2 with C3 –C4 recovery from the tail gas). b Syncrude waste products and unrecoverable material (e.g., carboxylic acids in wastewater).

575

576

27 Diesel Fuel Refining Carbonyl hydrogenation

Aqueous

C3 –C4

Wastewater LPG Gasoline

SPA alkylation oligomerization

C5 LTFT gas loop

Hot and cold condensate

Alcohols

Hydrotreater

Jet fuel

C5 hydroisomerization

Gasoline

C6 –C10

Oligomerization

Hydrotreater

Benzene

C6 –C8

Nonacidic Pt / L reforming

Hydrocracker

Wax

H2 Fuel gas Gasoline Jet fuel Diesel

Diesel

C23 and heavier

Figure 27.9 LTFT diesel fuel refinery design case I with an additional naphtha oligomerization unit to boost diesel fuel yield, when there is no minimum density specification requirement. The gas loop includes C3 –C4 recovery with recycling of the C1 –C2 hydrocarbons in the tail gas.

27.5.2 LTFT Diesel Fuel Design Case II

When the diesel fuel must meet minimum density and cetane number requirements, the refinery design is subject to the limitations described by the density–cetane–yield triangle. A refinery design strategy can be followed that employs the lever rule to balance high-cetane-number, low-density material with low-cetane-number, high-density material (Section 27.3.6). The high cetane number of the gas oil fraction from LTFT wax hydrocracking provides enough leverage in combination with alkyl aromatics to just meet the diesel fuel specifications (Figure 27.10). It illustrates the dilemma of refining paraffinic material to diesel fuel. Central to the design is the selection of the cracking unit. Refinery designs for the production of on-specification EN590:240 diesel fuel from LTFT syncrude that have been proposed in the literature [8, 32] employed fluid catalytic cracking for wax conversion. In each instance, diesel fuel was not the major product, and the selection of fluid catalytic cracking instead of hydrocracking was dictated by the refining requirements of the other transportation fuels. The high distillate

27.5 Diesel Fuel Refining from LTFT Syncrude

yield that can be obtained by wax hydrocracking is forfeited because it is not possible to produce on-specification diesel fuel in high yield. The operating window for on-specification diesel fuel production is small. The diesel fuel just meets specification (Table 27.5), and the base case design includes 5% FAME addition. The diesel

Table 27.5

Products from LTFT diesel fuel refinery design case II shown in Figure 27.10.

Description Product distribution (mass%)a H2 Fuel gas LPG Motor-gasoline Jet fuel Diesel fuel Petrochemicals produced Petrochemicals consumed Unrecovered organicsc Water to/from refining Liquid fuels (m3 ·t –1 )a LPG Motor-gasoline Jet fuel Diesel fuel Net productiona Liquid fuels (m3 ·t –1 ) Petrochemicals (kg·t –1 ) Fuel gas (kg·t –1 ) Motor-gasoline properties RON MON Density at 15 ◦ C (kg·m –3 ) Reid vapor pressure (kPa) Alkene content (vol%) Aromatic content (vol%) Benzene content (vol%) Oxygenate content (vol%) Jet fuel properties Density at 15 ◦ C (kg·m –3 ) Aromatic content (vol%) Diesel fuel properties Cetane number Density at 15 ◦ C (kg·m –3 ) a On

Fe-LTFT

Co-LTFT

0.8 1.2 6.6 33.2 31.2 22.9 3.2 −1.1b 1.7 0.3

1.0 1.2 8.9 35.6 28.4 23.6 1.3 −1.2b 0.9 0.3

0.120 0.444 0.401 0.279

0.161 0.478 0.363 0.288

1.244 20 20

1.290 1 22

98.1 90.6 747 60 10.4 34.0 0.5 0.0

98.0 90.3 744 60 12.7 32.5 0.5 0.0

779 22.9

782 24.7

51 820

51 820

a syncrude basis, excluding H2 , CO, CO2 , H2 O, and C1 –C2 hydrocarbons from LTFT synthesis (closed gas loop with C3 –C4 recovery from the tail gas). b Fatty acid methyl ester imported for blending. c Syncrude waste products (e.g., coke on FCC catalyst) and unrecoverable material (e.g., carboxylic acids in wastewater).

577

578

27 Diesel Fuel Refining Carbonyl hydrogenation

Aqueous

Wastewater LPG Gasoline

SPA alkylation oligomerization

C3 – C4

LTFT gas loop

Alcohols

C5

C3 – C4

C5

Hydrotreater

Jet fuel Diesel

C5 hydroisomerization

Gasoline

Benzene Hot and cold condensate

Nonacidic Pt / L reforming Hydrotreater

H2 Fuel gas Gasoline Jet fuel Diesel

Wax FCC

Fuel gas

Wax

Figure 27.10 LTFT jet fuel refinery design case II, which maximizes diesel fuel yield when there is a minimum density specification requirement. The gas loop includes C3 –C4 recovery with recycling of the C1 –C2 hydrocarbons in the tail gas.

fuel is very aromatic and, although the aromatics are almost exclusively mononuclear aromatics, the design in Figure 27.10 is only of theoretical interest. Although the design is capable of producing some on-specification diesel fuel, it is clearly not an elegant solution, and in practice blending or co-refining is preferable.

References 1. Weil, B.H. and Lane, J.C. (1949) The Technol-

5. (2009) Directive 2009/30/EC of the European

ogy of the Fischer-Tropsch Process, Constable, London. 2. Freerks, R. (2003) Early efforts to upgrade Fischer-Tropsch reaction products into fuels, lubricants and useful materials. AIChE Spring National Meeting, 2 April, 2003, New Orleans, paper 86d. 3. Hardenberg, H.O. (1980) Thoughts on an ideal diesel fuel from coal. S. Afr. Mech. Eng., 30, 34–47. 4. Boehman, A.L., Szybist, J.P., Song, J., Zello, V., Alam, M., and Miller, K. (2004) Combustion characterization of GTL diesel fuel. Prepr. Pap.-Am. Chem. Soc., Div. Fuel Chem., 49 (2), 714–716.

Parliament and of the Council of 23∼April 2009 amending Directive 98/70/EC as regards the specification of petrol, diesel and gas-oil and introducing a mechanism to monitor and reduce greenhouse gas emissions and amending Council Directive 1999/32/EC as regards the specification of fuel used by inland waterway vessels and repealing Directive 93/12/EEC. Off. J. Eur. Union, L140, 88. 6. Reid, R.C., Prausnitz, J.M., and Poling, B.E. (1987) The Properties of Gases and Liquids, 4th edn, McGraw-Hill, New York. 7. Mushrush, G.W., Willauer, H.D., Bauserman, J.W., and Williams, F.W. (2009) Incompatibility of Fischer-Tropsch diesel with petroleum and

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soybean biodiesel blends. Ind. Eng. Chem. Res., 48, 7364–7367. De Klerk, A. (2009) Can Fischer-Tropsch syncrude be refined to on-specification diesel fuel? Energy Fuels, 23, 4593–4604. Santana, R.C., Do, P.T., Santikunaporn, M., Alvarez, W.E., Taylor, J.D., Sughrue, E.L., and Resasco, D.E. (2006) Evaluation of different reaction strategies for the improvement of cetane number in diesel fuels. Fuel, 85, 643–656. Leckel, D.O. (2009) Hydroprocessing Euro 4-type diesel from high-temperature Fischer-Tropsch vacuum gas oils. Energy Fuels, 23, 38–45. De Klerk, A. and Furimsky, E. (2010) Catalysis in the Refining of Fischer–Tropsch Syncrude, Royal Society of Chemistry, Cambridge. Knottenbelt, C. (2002) Mossgas ‘‘gas-to-liquids’’ diesel fuels – an environmentally friendly option. Catal. Today, 71, 437–445. Pecci, G.C., Clerici, M.G., Giavazzi, F., Ancilotti, F., Marchionna, M., and Patrini, R. (1991) Oxygenated diesel fuels. Part 1 – Structure and properties correlation. 9th International Symposium on Alcohols Fuels, 1991, pp. 321–326. Knothe, G. and Steidley, K.R. (2005) Lubricity of components of biodiesel and petrodiesel. The origin of biodiesel lubricity. Energy Fuels, 19, 1192–1200. (2001) Linear Alpha Olefins, SRI Process Economics Program Report 12D, Stanford Research Institute, Menlo Park, CA. De Klerk, A. (2007) Thermal cracking of Fischer-Tropsch waxes. Ind. Eng. Chem. Res., 46, 5516–5521. Ribeiro, N.M., Pinto, A.C., Quintella, C.M., Da Rocha, G.O., Teixeira, L.S.G., Guariero, L.L.N., Do Carmo Rangel, M., Veloso, M.C.C., Rezende, M.J.C., Da Cruz, R.S., De Oliveira, A.M., Torres, E.A., and De Andrade, J.B. (2007) The role of additives for diesel and diesel blended (ethanol or biodiesel) fuels: a review. Energy Fuels, 21, 2433–2445. Marchionna, M., Patrini, R., Giavazzi, F., and Pecci, G.C. (1996) Linear ethers as high quality components for reformulated diesel fuels. Prepr. Pap.-Am. Chem. Soc., Div. Petrol. Chem., 41 (3), 585–589. Steiner, H. (1956) in Catalysis Vol. IV, Hydrocarbon synthesis, hydrogenation and cyclization,

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(ed. P.H. Emmett), Reinhold, New York, pp. 529–560. Kocal, J.A., Vora, B.V., and Imai, T. (2001) Production of linear alkylbenzenes. Appl. Catal. A, 221, 295–301. Naegeli, D.W., Childress, K.H., Moulton, D.S., and Lacey, P.I. (2002) Method for producing oxygenates fuels. Patent US 6,488,727. Lamprecht, D. (2007) Elastomer compatibility of blends of biodiesel and Fischer-Tropsch diesel. SAE Tech. Pap. Ser., 2007−01–0029. Androulakis, I.P., Weisel, M.D., Hsu, C.S., Qian, K., Green, L.A., Farrell, J.T., and Nakakita, K. (2005) An integrated approach for creating model diesel fuels. Energy Fuels, 19, 111–119. Wu, T., Huang, Z., Zhang, W.-G., Fang, J.-H., and Yin, Q. (2007) Physical and chemical properties of GTL-diesel fuel blends and their effects on performance and emissions of a multicylinder DI compression ignition engine. Energy Fuels, 21, 1908–1914. Gregor, J.H. (1990) Fischer-Tropsch products as liquid fuels or chemicals. An economic evaluation. Catal. Lett., 7, 317–332. Lamprecht, D. (2009) Blending performance of hydroprocessed coal pyrolysis products in low-temperature Fischer-Tropsch diesel. Prepr. Pap.-Am. Chem. Soc., Div. Fuel Chem., 54 (1), 120–121. Leckel, D.O. (2009) Hydroprocessing CTL diesel from high-temperature Fischer-Tropsch syncrude and pyrolysis tar oil. Prepr. Pap.-Am. Chem. Soc., Div. Fuel Chem., 54 (1), 125–126. Kamara, B.I. and Coetzee, J. (2009) Overview of high-temperature Fischer-Tropsch gasoline and diesel quality. Energy Fuels, 23, 2242–2247. Leckel, D.O. (2009) Diesel production from Fischer-Tropsch: the past, the present, and new concepts. Energy Fuels, 23, 2342–2358. Anastopoulos, G., Lois, E., Serdari, A., Zanikos, F., Stournas, S., and Kalligeros, S. (2001) Lubrication properties of low-sulfur diesel fuels in the presence of specific types of fatty acid derivatives. Energy Fuels, 15, 106–112. (2008) Sasol proposes Project Mafutha CTL plant. Oil Gas J., 106 (4), 10–11. De Klerk, A. (2011) Fischer-Tropsch fuels refinery design. Energy Environ. Sci., 4, 1177–1205.

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Chemicals and lubricants are the higher value, lower volume cousins of the transportation fuels. There is consequently an economic incentive to produce these higher value products when the refinery (and market) permits. Central to the refining of syncrude to chemicals and lubricants is whether these products can be produced on their own, or whether these products must be produced in conjunction with fuel refining. This is not clear cut, and a similar question has been raised in relation to crude oil [1]: ‘‘Whether or not the production of chemicals from crude oil can be independent of the production of fuels has still not been determined.’’ The conundrum can be traced back to the molecular makeup of the syncrude or crude oil. There is a subset of refining technologies that lend themselves to the production of petrochemicals. Likewise, some compounds are easily refined to chemicals and lubricants. However, the selectivity to chemicals and lubricants, even from well-designed petrochemical technologies and appropriate feed materials, is never 100%. Chemicals are usually single-compound products with stringent quality specifications. Nonchemical products cannot be blended away into chemicals, as is the case with products that are mixtures, such as fuels. Lubricants, being a mixture of compounds, are more forgiving products, but there is still a limit to which nonlubricant material can be blended away. So, what do you do with the material that is neither a chemical nor a lubricant? Unless one can recycle the material to be converted into chemicals or lubricants, fuel production becomes inevitable. The high value of chemicals and lubricants allows a higher rejection rate of material as refinery fuels, but there is a limit to the amount of refinery fuel required. Ultimately, some material may have to be sold as heating or transportation fuels. Furthermore, materials that were produced during chemical and lubricant refining may be difficult to convert into either of these products, thereby reducing the efficiency of the refinery, if one wanted to do so. This seems to be the case for crude oil [2], but is it true of syncrude as well? The gradual conversion of some of the industrial Fischer–Tropsch facilities to increase the production of chemicals (Chapters 8 and 9), as well as the intentional production of chemicals and lubricants in new facilities (Chapter 11), indicates that syncrude has considerable potential for chemical and lubricant production. The extent to which syncrude can be converted into chemicals and lubricants will be discussed. Concepts that were proposed in the literature for chemical and lubricant refining from syncrude are evaluated (Section 28.3). Then the extent to which syncrude can efficiently be refined to chemicals and lubricants is explored (Sections 28.4 and 28.5). Fischer–Tropsch Refining, First Edition. Arno de Klerk.  2011 Wiley-VCH Verlag GmbH & Co. KGaA. Published 2011 by Wiley-VCH Verlag GmbH & Co. KGaA.

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28.2 Petrochemical and Lubricant Markets 28.2.1 Petrochemicals

The petrochemical market is much smaller than the energy market. It was estimated that the global energy consumption in 2007 was 465 EJ (441 quadrillion BTU), of which 298 EJ was derived from fossil fuels and 27 EJ was employed for chemical production [3]. The main commodities and how each is related to the raw materials employed for production are shown in Figure 28.1 [3]. Despite its comparatively small market share in the overall energy sector, there are many opportunities for the conversion of Fischer–Tropsch syncrude into petrochemicals. Petrochemicals are higher value products and are economically more enticing products than transportation fuels. Herein lies a risk too. A common fallacy that is sometimes perpetrated in evaluating chemical opportunities is that the market will not respond to the additional production capacity. This is not true, since the global installed capacity often exceeds the global consumption. The logistics cost associated with chemical production will favor producers based on their proximity to the consumers. Gaining market share by selling product at a lower price can lead to a price war, which quickly erodes profitability. The prospective petrochemical refinery designer should be aware of ‘‘shut-down economics.’’ This requires careful competitor analysis to determine for how little a chemical can be sold from an existing but competing production facility, without running the facility at a loss. The risk of a hostile response to entry into a specific petrochemical market increases with decreasing market size. Raw material

Feed fraction

Commodities

Methane

1.1 EJ

Products

Methanol, etc.

Natural gas Natural gas liquids

4.5 EJ

Ethane, propane, butane condensates

Ethene, propene, butadiene, etc.

Refinery off-gas

Crude oil Refinery liquids

21.2 EJ

Naphtha gas oil

Coal

Coal pyrolysis liquids

0.08 EJ

Benzene, toluene, xylenes, etc.

Figure 28.1 Petrochemical production showing the origin and energy flow in 2007 and indicating the seven highest volume primary commodity chemicals.

Plastics, solvents, surfactants, elastomers, coatings, fibres, etc.

28.2 Petrochemical and Lubricant Markets

A Fischer–Tropsch-based petrochemical facility carries a large capital cost burden, making it more vulnerable to a hostile response. For a new Fischer–Tropsch facility, the actual petrochemical production cost must include the operating cost and the cost of capital. An established Fischer–Tropsch facility runs a lower risk when it enters a niche market for petrochemicals, but when designing a new Fischer–Tropsch-based petrochemical facility it is better to focus on large-volume commodity chemicals where there is less risk of a hostile market. The focus in the remainder of the chapter is therefore on large-volume commodity chemicals, while acknowledging that there are many opportunities for smaller volume petrochemicals. The largest volume primary commodity chemicals are listed in Table 28.1 [3]. The market is growing and, by producing any of these petrochemicals from Fischer–Tropsch syncrude, it is unlikely to upset the market or price. Of these, ethene and propene are primary Fischer–Tropsch products and constitute 15–20% of a typical HTFT (high-temperature Fischer–Tropsch) syncrude [4], but much less of LTFT (low-temperature Fischer–Tropsch) syncrude. The primary commodity chemicals are used in the manufacture of various derived petrochemicals, although the derived petrochemicals are not exclusively obtained from the primary commodity chemicals. These primary commodity chemicals are also called first-generation intermediates [5]. The derived petrochemicals in general have a higher value than the primary commodities. Since some of these derived products also have large markets, further value addition within a Fischer–Tropsch petrochemical refinery can be considered without increasing the risk. This may be especially desirable when the derived product has a large petrochemical market and good transportation fuel properties. Such chemicals provide an easy reincorporation pathway into the refinery by direct fuel blending, making the refinery design more robust. The market sizes of some derived petrochemicals that may be of interest in the design of a Fischer–Tropsch petrochemical refinery are given in Table 28.2 [6]. These are of course not the Global consumption of the largest volume primary commodity chemicals for the period 2005–2007.

Table 28.1

Primary commodity

Global consumption (million tons per year) 2005

Alkenes Ethane Propene Butadiene Aromatics Benzene Toluene Xylenes Oxygenatesa Methanol

2006

2007

105.6 66.7 9.5

110.1 70.7 9.7

114.6 73.5 10.1

37.5 18.8 35.2

38.5 19.8 37.6

40.6 20.9 40.7

36.7

38.9

40.6

a Ethanol is used as chemical and fuel and has therefore not been included.

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28 Chemicals and Lubricant Refining Table 28.2 Products and markets relevant to petrochemical production from Fischer–Tropsch syncrude.

Petrochemical product

Cumene Detergent alcohols Ethanoic acid (acetic acid) Ethanola Linear alkanes, C9 –C17 (paraffins) Linear 1-alkenes (linear α-olefins) Linear alkylbenzene sulfonates Phenol Plasticizer alcohols 1-Butanol 2-Ethylhexanol Isononanol Propanoic acid Waxes a Volume-based

Global consumption Million tons per year

Year

11.9 2.0 10.6 57.3 2.9 2.7 4.1 8.6 8.0 2.8 2.8 1.0 0.3 3.0

2007 2008 2009 2008 2007 2006 2008 2007 2008 2008 2008 2008 2009 2005

market for chemicals and fuels: 72 681 million liters per year in 2008.

only chemicals that can be considered, but it gives an indication of the opportunities that exist for the refining Fischer–Tropsch syncrude to petrochemicals. 28.2.2 Lubricants

The lubricant base oil market size is on the order of 40 million m3 /year [7]. Compared to the petrochemicals, it is a much smaller market. It is nevertheless of interest to the Fischer–Tropsch refiner, because high-quality lubricant base oils can be prepared from LTFT waxes [8] as well as from n-1-alkenes in the heavy naphtha and kerosene fractions of HTFT and LTFT syncrude. The American Petroleum Institute (API) classifies lubricant base oils into five groups (Table 28.3). The viscosity index (VI), which is calculated in accordance with the ASTM D 2270 method [9], is a key quality parameter. The VI is a measure of the temperature sensitivity of the kinematic viscosity of the oil. A high-VI oil retains more of its viscosity as the temperature is increased than a low-VI oil. VI is not the only performance parameter. Among others, good cold-flow properties, kinematic viscosity, volatility, lubricity, and oxidation stability are also important quality parameters. Good biodegradability and low toxicity are also desirable properties. Lubricant base oils can be produced from Fischer–Tropsch syncrude in API groups III–V by using different feed fractions and conversions: 1) API group III lubricant base oils. These oils can be prepared from LTFT waxes [8] and HTFT residues [10]. In the case of LTFT-derived base oils, the branched alkane content can be

28.3 Overview of Chemicals Refining Concepts for Syncrude Table 28.3

American Petroleum Institute (API) classification of lubricant base oils.

API classification

Sulfur content (mass%)

Group I Group II Group III Group IV Group V

>0.03a ≤0.03 ≤0.03

Saturates (mass%)

C9

Decanted oil Aqueous product

Reforming (nonacid Pt/L)

Gasoline Distillate

Hydrotreater/ hydrocracker

Oxygenate recovery

Alcohols Ketones

Simple HTFT fuels and chemicals refinery with 37% yield of chemicals.

28.4 Fischer–Tropsch-Based Petrochemical Refining Ethene

Ethene

C2-rich tail gas

Thermal cracking

Ethane

LPG Propene

C3

C4

Oligomerization (SPA)

HTFT condensate

Hydrotreater

Gasoline TAME

Etherification

C5 skeletal isomerization

C5

Benzene

C6

C5 Hydroisomerization

Gasoline

Aromatic alkylation

Cumene H2, LPG, gasoline

Reforming (nonacid Pt/L)

Light oil C9 –10 >C9

Alcohols

Aromatic alkylation

Distillate LAB

C15

Gasoline Distillate

Oxygenate recovery

Alcohols Ketones

Complex HTFT fuels and chemicals refinery with 49% yield of chemicals.

found that with a simple HTFT combined fuels and chemicals refinery (Figure 28.4), 37% of the syncrude could be recovered as chemicals, and with a more complex refinery (Figure 28.5) 49% of the syncrude could be recovered as chemicals (Table 28.5) [4]. In both instances, the objective was to employ refining technologies that had good synergy with Fischer–Tropsch syncrude, rather than increasing the chemicals yield with technologies that did not have an inherently good fit.

28.4 Fischer–Tropsch-Based Petrochemical Refining 28.4.1 Alkane Refining

Most alkane-based petrochemicals are mixtures of alkanes with specific volatility (boiling range) requirements, or melting point properties in the case of waxes. The refining of alkane-based

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28 Chemicals and Lubricant Refining Table 28.5 Mass balances for HTFT combined fuels and chemicals refinery concepts shown in Figures 28.4 and 28.5.

Products

Combined fuels and chemicals refining (mass%) Figure 28.4

Commodity chemicals LPG Motor-gasoline Distillate Nonrecoverable productsa a Organic

37 6 39 13 5

Figure 28.5 49 6 31 10 4

products not recovered and wastewater produced during oxygenate refining.

petrochemicals is dominated by separation processes to obtain the different product fractions. Hydroprocessing is the only type of conversion that is required. Hydrotreating ensures that all reactive functional groups are removed and is also useful in addressing properties such as color and odor. Hydroisomerization may be required to adjust properties such as hardness (penetration) and cold flow. A typical alkane-based petrochemical refinery is shown in Figure 8.12. The petrochemical production of alkanes is best performed using LTFT syncrude as feed material. The Fischer–Tropsch technology affects the syncrude properties, and not all LTFT or HTFT syncrudes have similar properties or are equally well suited for alkane production. Nevertheless, generally speaking, LTFT syncrudes have a number of advantages over HTFT syncrude for alkane-based petrochemicals: 1) 2) 3) 4) 5)

It contains a large fraction of n-alkane waxes. It contains little aromatics. The oxygenates are mainly n-alcohols, which are easily converted into n-alkanes. It is alkane rich, rather than alkene rich. It has a higher ratio of linear to branched isomers.

Because of the large wax fraction in LTFT syncrude, an important petrochemical alternative is lubricant base oil production (Section 28.5). 28.4.2 Light Alkene Refining

The carbon number distribution of HTFT syncrude is such that a large fraction of the straight-run syncrude is in the C2 –C4 range. This naturally favors light alkene recovery. Even though LTFT syncrude has less material in the C2 –C4 range, the light alkenes are still present in percentage levels. Of the LTFT technologies, slurry bed Fe-LTFT is preferred for light alkene production, and deactivation of the Fe-LTFT catalyst over time results in an added selectivity advantage. Fischer–Tropsch-based petrochemical facilities can be designed to exploit advantages that are inherent to the technology. In some respects it makes syncrude a better raw material for

28.4 Fischer–Tropsch-Based Petrochemical Refining

light alkene production than either crude oil or natural gas. The specific advantages include the following: 1) The C2 –C4 hydrocarbons are free from heteroatom contaminants. 2) Cryogenic separation, which is needed for the production of ethene, also benefits the Fischer–Tropsch gas loop design and the overall carbon efficiency of the facility. 3) The straight-run C2 –C4 alkenes are primary products. 4) By including a methane reformer in the Fischer–Tropsch gas loop, methane can be converted back into synthesis gas. In this way, methane produced during petrochemical refining and Fischer–Tropsch synthesis is not a product with no further potential for upgrading. 5) The light alkanes can be refined to light alkenes in an analogous way to crude-oil-derived light alkanes, but it is sulfur free and reportedly has a selectivity advantage [32]. 6) Light alkenes can also be produced with high selectivity by dehydration of alcohols in the Fischer–Tropsch aqueous product [33]. 7) Fischer–Tropsch synthesis can be tailored to increase light alkene selectivity. The straight-run alkene production can be increased by decreasing the degree of hydrogenation that takes place during Fischer–Tropsch synthesis: for example, by selecting a reactor with less plug-flow behavior or using a Fischer–Tropsch catalyst that is less hydrogenating. The production of straight-run C2 –C4 hydrocarbons can be further increased by adjusting the chain growth probability (α-value) of the Fischer–Tropsch catalyst (Figure 28.6). A decrease in the α-value comes at the expense of increased methane production, as well as increased water-soluble oxygenate selectivity. The maximum yield of straight-run C2 –C4 hydrocarbons is therefore not necessarily defining the optimum operating point.

70

C2 –C4

60

Yield (mass%)

50 40 C1

30 20

C5 –C10 (naphtha)

10 C11 and heavier

0 0.3

0.4

0.5 0.6 0.7 Fischer–Tropsch chain growth probability

Figure 28.6 Yield of light hydrocarbons from Fischer–Tropsch synthesis as calculated from the Anderson–Schulz–Flory distribution. The yield of C1 –C2 was estimated on the basis of the C3 yield.

0.8

0.9

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28 Chemicals and Lubricant Refining

Purge Methane reformer

H2

PSA

CH4 + H2 Ethane

Tail gas

Cryogenic separation

Ethene

C3 –C4 separation

Propene Butenes Butadiene

C3 –C4 alkanes

Syngas

Fischer – Tropsch synthesis

Thermal cracking

Pyrolysis oil

Oil Alcohol dehydration Carbonyl hydrogenation

Aqueous

Figure 28.7

Alcohols Wastewater

Stand-alone Fischer–Tropsch-based petrochemical facility producing light alkenes.

The ability to manipulate the product distribution from Fischer–Tropsch synthesis (Section 4.4), in combination with an appropriate petrochemical refinery design, provides a unique opportunity for light alkene production. It is possible to envisage a stand-alone petrochemical facility that produces mainly C2 –C4 alkenes (Figure 28.7). The recovery of straight-run Fischer–Tropsch alkenes is combined with additional alkene production in the syncrude refinery. The main unit is a thermal cracker, which converts various feed materials into light alkenes. There is synergy in such a combination of Fischer–Tropsch synthesis with thermal cracking, because the light gas separation section can be shared. By purifying the Fischer–Tropsch tail gas together with the cracked gas, the overall capital cost of the facility is reduced. The feed to the thermal cracker is a combination of the straight-run C5 and heavier oil product and the C2 –C4 alkanes from light alkene recovery. In the design shown in Figure 28.7, the aqueous product is refined separately and only the tail gas separation section is shared. The carbonyl compounds in the aqueous product are selectively hydrogenated to produce alcohols, which are then dehydrated with the alcohols that are already present in the aqueous product. A high selectivity of ethene from ethanol and propene from propanol can be obtained in this way. A simplification of the design involves the conversion of the aqueous product oxygenates with the other material in the thermal cracker, albeit at lower selectivity to the targeted alkenes. 28.4.3 Linear 1-Alkene Refining

Straight-run Fischer–Tropsch syncrude contains alkenes that are petrochemical products. The extraction of these n-1-alkenes is practised industrially, and the technologies for such extraction

28.4 Fischer–Tropsch-Based Petrochemical Refining

were discussed (Chapter 23). It is possible to recover n-1-alkenes from both HTFT and LTFT syncrude, but for each carbon number the concentration of the n-1-alkenes is lower in LTFT than HTFT syncrude. HTFT syncrude is the preferred feed material for the production of n-1-alkenes. Although the n-1-alkene market is very lucrative, designing a Fischer–Tropsch-based petrochemical facility for the production of n-1-alkenes should take into account the following: 1) The total market for all n-1-alkenes (Table 28.2) is much smaller than that of the primary commodity chemicals (Table 28.1). 2) Recovering n-1-alkenes from syncrude must compete with n-1-alkene synthesis from ethene. The complexity of the purification of n-1-alkenes from syncrude increases with the carbon number. The trade-off is analogous to that between direct and indirect liquefaction. Direct recovery of n-1-alkenes is more efficient, but further refining to remove impurities is more demanding. Producing n-1-alkenes indirectly from ethene has an inherent purity advantage, although the initial production cost is higher. 3) Fischer–Tropsch synthesis determines the n-1-alkene content in the syncrude. Since production relies on refinery separation, not conversion, the yield is fixed. 4) Petrochemical production of n-1-alkenes targets only a fraction of the syncrude, and for the most part the design of such a petrochemical facility will be determined by the refining of the remainder of the syncrude. One would not design a facility primarily for the production of n-1-alkenes. 28.4.4 Aromatics Refining

There are four technologies that can be considered for the production of aromatics from Fischer–Tropsch syncrude: Conventional catalytic naphtha reforming over Pt/Cl− /Al2 O3 -based catalysts (Section 22.3). The majority of the C6 –C8 aromatic petrochemicals are produced from crude oil in this way. Because of the low N + 2A of syncrude, it is not an efficient technology for syncrude conversion into aromatics. 2) Monofunctional naphtha reforming over nonacidic Pt/L-zeolite-based catalysts (Section 22.4). Industrially, some of the C6 –C8 aromatic petrochemicals are produced from crude-oil-derived naphtha in this way, despite the extreme sulfur sensitivity of the catalyst. This technology has an excellent technology fit with syncrude, not only due to the sulfur-free nature of the syncrude but also due to the high linear hydrocarbon content. It has the further advantage that benzene can directly be produced in high yield from hexane, rather than through toluene disproportionation. 3) Aromatization of hydrocarbons over Ga- or Zn/H-ZSM-5-based catalysts (Section 22.5). Industrially, some of the C6 –C8 aromatic petrochemicals are produced in this way. This type of aromatic conversion can be efficiently integrated with a Fischer–Tropsch gas loop for tail gas aromatization (Figure 22.7). It is also a useful alternative to thermal cracking for the conversion of light alkanes into petrochemicals. 4) Carbonyl aromatization over acidic catalysts (Section 16.3.5). This conversion is not industrially applied for aromatics production. Although it is capable of producing some aromatics 1)

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28 Chemicals and Lubricant Refining

Purge Methane reformer

PSA

CH4 rich

Syngas

Ethane Fischer – Tropsch synthesis

Tail gas

H2

Cryogenic separation

Ethene

C3 – C4 separation

Propene Butenes Butadiene

C3 –C4 alkanes

Oil

Aromatization

C5

Aromatics

Hydrotreater

C6 –C10 Reforming

Gas Oil

Gas

Aromatics separation

Aromatics

Aliphatics

Thermal cracking

Aqueous

Wastewater

Figure 28.8 Stand-alone Fischer–Tropsch-based petrochemical facility producing light alkenes and aromatics.

from HTFT syncrude, only ethanal yields BTX aromatics, but ethanal is present in too small an amount to contribute significantly to petrochemical production. These aromatics-producing technologies all make use of C10 and lighter material. A stand-alone Fischer–Tropsch-based petrochemical complex for aromatics production only is therefore impractical. A cracking unit to convert the heavier material is suggested, which implies that alkene and aromatics should preferably be coproduced, as is often found in petrochemical facilities. The α-value can be manipulated to yield mainly C10 and lighter products (Figure 28.6) to avoid a cracking unit, but when doing so the light olefinic syncrude still favors alkene and aromatics coproduction. Conceptually, alkene and aromatics production goes hand in hand, and it opens downstream refining pathways for the production of commodities such as ethylbenzene, styrene, and cumene. A stand-alone Fischer–Tropsch-based petrochemical facility (Figure 28.8) has many design features in common with a crude-oil-based facility (Figure 2.14). However, integration of light hydrocarbon separation with the Fischer–Tropsch gas loop, the lighter carbon number distribution, and the more reactive sulfur-free syncrude make such a facility more efficient. The ratio of alkene to aromatics production can be changed by routing more material to the cracker and including only a single aromatics production technology.

28.5 Fischer–Tropsch-Based Lubricant Base Oil Refining

28.4.5 Oxygenate Refining

Industrial designs for the recovery and separation of oxygenates from the Fischer–Tropsch aqueous product were discussed (Sections 7.4.2, 8.4.3, 9.4.3, and 10.4.2). Aqueous product refining concepts were also discussed in the context of fuels refinery design (Section 25.3.4). Oxygenates can be recovered from the Fischer–Tropsch oil product by the separation strategies employed for n-1-alkene separation (Section 23.2). However, many of the heavier oxygenates are not large-volume commodities, and the concentration of plasticizer and detergent range alcohols present in straight-run syncrude is comparatively low. Unless the Fischer–Tropsch technology is selected to produce a larger concentration of alcohols, the alcohol concentration is insufficient to justify extraction and purification as petrochemicals. If the objective is to produce alcohols specifically as the primary synthesis product, one should consider syngas-to-methanol technology [34] instead of Fischer–Tropsch synthesis. There are also various accounts of oxygenate-selective Fischer–Tropsch-type catalysts in the literature if oxygenates other than methanol is of interest. However, oxygenate recovery and purification from a complex matrix is not trivial, and this may not be the most efficient route for the large-scale production of heavier oxygenate-based chemicals. Oxygenates can be synthesized from hydrocarbons with good selectivity, and industrially most of the heavier oxygenates are prepared in this way. Specific synthetic routes that can be considered in conjunction with syncrude are the following: 1) Alcohol synthesis by hydroformylation of alkenes (Section 16.3.6). Syncrude contains not only n-alkenes in significant concentration, but H2 and CO are available from the syngas in the Fischer–Tropsch gas loop. Short-chain alcohols can also be synthesized by direct hydration of alkenes (Section 17.4). 2) Oxidized hydrocarbons through autoxidation of alkanes (Section 23.3). There is no clear syncrude advantage, except with respect to feed availability and maybe purity for some specific cuts. There are many other possibilities, and syncrude can in principle be employed as feed material for any of the oxygen-containing petrochemicals that are synthesized from crude oil.

28.5 Fischer–Tropsch-Based Lubricant Base Oil Refining

Lubricant base oil is a heavy product. Processing a full-range Fischer–Tropsch syncrude to lubricant base oil in a stand-alone facility will have to be combined with either fuels or petrochemicals production in order to be efficient. The main classes of lubricants that can be easily produced in large volume from syncrude are the following: 1) API Group III lubricant base oils prepared from the Fischer–Tropsch residue fraction by hydroisomerization and mild hydrocracking. LTFT syncrude is the preferred feed material and it does not require extensive hydrodearomatization (HDA) as in the case of HTFT syncrude. The volume of lubricant that can be produced is determined by the syncrude employed, but additional lubricant can be produced by oligomerization.

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28 Chemicals and Lubricant Refining

2) API Group IV lubricant base oils prepared from the alkenes in syncrude. The n-1-alkenes can be converted into PAO lubricant base oils, the quality being dependent on the carbon number range of the alkenes and the internal alkene content. PIO lubricant base oils can be readily prepared. In both cases, the syncrude must be deoxygenated and an appropriate oligomerization catalyst must be selected. The volume of the latter can be increased through autoxidation and dehydration of the alkanes to increase the internal alkene content. The volume of PAO lubricant is limited by the type of syncrude employed. The volume of PIO lubricant can be readily increased through refining. It is possible to produce some API group V lubricant base oils, but not in the same yields or with the same ease as the group III and IV lubricant base oils. Since the group V lubricant base oils are all synthetic oils, in principle one can use syncrude like crude oil as feedstock, but in such syntheses the syncrude has no specific advantage over crude oil. The two classes of lubricant base oils that have a potential feedstock advantage are the esters and neutral trialkyl phosphate esters. In both cases, the feedstock advantage comes from the 1-alcohols in the syncrude, the volume of which may be increased through synthesis (Section 28.4.5). Ester-based lubricants employ naphtha and distillate range 1-alcohols. Lubricant base oil can be produced by in situ esterification, which has processing synergy with hydroformylation as a feed preparation step, albeit using longer chain alcohols [35]. Neutral trialkyl phosphate esters are also produced from naphtha and distillate range 1-alchols. Industrially, the dominant route for synthesis is the reaction of the alcohols with phosphorus oxychloride [36]. 28.5.1 Group III Lubricant Refining

The refining of LTFT waxes into lubricating base oil combines the removal of one of the undesirable base oil constituents, namely waxes, with the production of a high-VI oil. The n-alkane waxes have a good VI in the liquid state, but are undesirable due to their high melting points. By introducing some branching into the molecular structure, the melting point is drastically lowered, but this is accompanied by a decrease in the VI of the isomerized product. There is a trade-off between the need for better cold-flow properties and retaining the inherently high VI of the n-alkanes. The VI of lubricant base oils prepared by the hydroisomerization and mild hydrocracking of LTFT wax is determined by the distillation range and the average number of branches per molecule in the oil. A correlation was developed to relate the average carbon number (ACN) and the average branching number (ABN) of the oil to the VI (Equations 28.1 and 28.2) [37]. VI = −0.0008χ 2 + 0.7599χ − 17.449 χ = (ACN)2 (ABN)−1

(28.1) (28.2)

The correlation was found to be independent of the aliphatic hydrocarbon feedstock and also of the operating conditions of hydroprocessing [37]. This makes sense, because it correlates molecular properties with the physical properties. When the correlation is used in conjunction with the cold-flow requirements, which is also related to the ACN and the ABN, it is possible to calculate the optimum degree of hydroisomerization.

28.5 Fischer–Tropsch-Based Lubricant Base Oil Refining

It can also be shown that a lubricating base oil produced from the atmospheric residue of LTFT syncrude will meet API group III specifications unless the degree of isomerization is extremely high. A dibranched C22 alkane has a calculated VI of 120. VIs of 150 and higher that were obtained by the hydroisomerization of thermally cracked Fischer–Tropsch wax and polyethylene waste plastic [38] are therefore understandable. The refining of HTFT residue to lubricant base oil has been demonstrated [10], and the refining is akin to the hydroprocessing of crude-oil-derived residues. 28.5.2 Group IV Lubricant Refining

It is only the alkene feed material employed for the production of PAO and PIO lubricant base oils that differs, namely n-1-alkenes and internal alkenes. The same catalysts and technologies can be otherwise employed. The alkenes are oligomerized (Chapter 19) and then hydrogenated. The challenge is to prevent skeletal isomerization, cracking, and double bond isomerization as side reactions during oligomerization. Brønsted acid–catalyzed processes are understandably unsuitable for PAO production, since double bond isomerization will result in the conversion of the n-1-alkenes into internal alkenes to produce PIO lubricant base oil. The selection of the catalyst [39] or the use of free radical oligomerization [40] is critical to the quality of the final product. The VI of the PAO lubricant base oil improves with increasing carbon number of the n-1-alkene used as oligomerization feed (Table 19.7). This can be understood in terms of the methylene chain index description of Kobayashi and coworkers [37], who related the VI to the chain length of branching structures. The methylene chain index is calculated from the sum of the methylene length (ML) contributions of all CH2 structures in the molecule (Equation 28.3) Methylene chain index = (MLi )1.5

(28.3)

Primary, tertiary, and quaternary carbons are not counted. It is only the lengths of the CH2 -containing branches that are counted (Figure 28.9). The longer the chain length of the n-alkyl branches, the higher the methylene chain length index, which is also an indirect measure of the ACN. The methylene chain length index is proportional to the VI (Equation 28.4). VI ∝ 2.4 · (Methylene chain index) ML = 5 2 1

ML = 2

4 3

ML = 6

2 5

(28.4)

1

1

3 2

5 4

6

1 2

ACN = 22 ABN = 2

ML = 3 3

Methylene chain index = 51.5 + 21.5 + 61.5 + 31.5 = 33.9 Figure 28.9 Calculation of the methylene chain index for aliphatic lubricant base oils as defined by Kobayashi and coworkers.

599

600

28 Chemicals and Lubricant Refining

Although this is just an empirical relationship of some quantitative value, it has considerable qualitative value. For example, it explains the increase in VI of PAO oil with increasing length of the alkene monomer, as well as their superior VI compared to those produced from internal alkene monomers of the same chain length. As such, it is useful as a guidance for developing a refining strategy to convert distillate range alkanes into PIO lubricant base oils. These distillate range alkanes are not suitable for conversion into API group III base oils, but can be converted into internal alkenes by catalytic dehydrogenation or autoxidation followed by an appropriate deoxygenation step [41]. The internal alkanes can then be oligomerized to PIO oils. On the basis of the methylene chain index (Equation 28.3), a PIO oil requires an internal alkene feed that is two carbon numbers heavier than the n-1-alkene feed for a PAO oil to achieve a comparable VI. In an LTFT lubricant base oil refinery, the contribution of group IV oils will be less than that of group III oils (Section 28.5.1). LTFT syncrude contains some n-1-alkenes that can be converted into PAO lubricant base oils. The amount of n-1-alkenes can be further increased by dehydration of the 1-alcohols if required. The distillate range alkanes can be converted into internal alkenes for conversion into PIO oils. In an HTFT lubricant base oil refinery, the relative abundance of alkenes favors the production of PAO and PIO oils over that of group III oils. 28.5.3 Lubricant Base Oil Refining

The heavier carbon number distribution of LTFT syncrude makes it a better feed material for lubricant base oil refining than HTFT syncrude. Most of the distillate and heavier material in the syncrude can be converted into lubricant base oils (Figure 28.10). The atmospheric residue and wax can be mildly hydrocracked and hydroisomerized to produce high-VI API group III lubricant base oils. Part of the distillate range material can also be Fischer – Tropsch synthesis

Oil

Tail gas Aqueous

Chemicals fuels

Fischer–Tropsch refinery

C5 –C10

C11 –C22

Dehydration/ deoxygenation

Oligomerization

Dehydrogenation

Oligomerization

PAO oil

>C22

PIO oil Hydrocracking/ hydroisomerization

Group III oil

Wax

Figure 28.10

Stand-alone Fischer–Tropsch-based lubricant base oil facility.

References

converted into lubricant base oils. The n-1-alkenes in the straight-run distillate, as well as those produced from 1-alcohol dehydration, can be oligomerized to API group IV PAO lubricant base oils. The alkanes can then be converted into internal alkenes, which can be oligomerized to PIO lubricant base oils. The naphtha and lighter material are not suitable for conversion into high-quality lubricant base oil. However, the naphtha and lighter fractions of syncrude make an excellent feed for petrochemical conversion (Section 28.4). It is not practical to design a stand-alone Fischer–Tropsch lubricant base oil refinery without an associated petrochemical or fuels refinery.

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Fischer-Tropsch aqueous phase refining by catalytic alcohol dehydration. Ind. Eng. Chem. Res., 46, 3558–3565. Tijm, P.J.A., Waller, F.J., and Brown, D.M. (2001) Methanol technology developments for the new millennium. Appl. Catal. A, 221, 275–282. Bolder, F.H.A. (2009) Removal of carboxylic acids in Fischer-Tropsch hydrocarbon product. Prepr. Pap.-Am. Chem. Soc., Div. Petrol. Chem., 54 (1), 1–3. Harris, J.S. (1952) in Phosphoric Acid, Phosphates and Phosphatic Fertilizers, 2nd edn (ed. W.H. Waggaman), Reinhold, New York, pp. 486–506. Kobayashi, M., Saitoh, M., Ishida, K., and Yachi, H. (2005) Viscosity properties and molecular structure of lube base oil prepared from Fischer-Tropsch waxes. J. Jpn. Petrol. Inst., 48 (6), 365–372. Miller, S.J., Shah, N., and Huffman, G.P. (2005) Conversion of waste plastic to lubricating base oil. Energy Fuels, 19, 1580–1586. Brennan, J.A. (1980) Wide-temperature range synthetic hydrocarbon fluids. Ind. Eng. Chem. Prod. Res. Dev., 19, 2–6. Seger, F.M., Doherty, H.G., and Sachanen, A.N. (1950) Noncatalytic polymerization of olefins to lubricating oils. Ind. Eng. Chem., 42, 2446–2452. Bolder, F.H.A., De Klerk, A., and Visagie, J.L. (2009) Hydrogenation of oxidized wax and a process to produce olefins from paraffins by autoxidation, selective hydrogenation, and dehydration. Ind. Eng. Chem. Res., 48, 3755–3760.

603

Index

a acid-catalyzed oligomerization, in acid interconversion 388 acid gas removal 67–69 – solvents and processes for 68 acid number, determination of 481 acid strength, in alkene oligomerization 375 acidic molecular sieve, pentene skeletal isomerization 359 acidic resin catalysts 341 – in alkene oligomerization 381–383 active carbon gasoline 124 adiabatic oxidative reforming 6, 53–54, 56–57 – advantages of 57 adiabatic prereforming 55–56 agglomeration 66 – in Co-LTFT catalysts 98 air pollution 39, 40–41 Air Quality Improvement Research Program (AQIRP) 40–41 air separation unit (ASU) 70–71, 70 ‘‘A-K’’ gasoline 130 Al Khaleej field 241 alcohol 136–137, 565, 588 – in biomass refining 310 – composition 137 – etherification 338 – and motor gasoline 263 – as primary autoxidation products 480 – refining 567 aldehydes 588 aldol condensation 336 aliphatic alkylation 223, 316–317 aliphatic hydrocarbons 124, 125 alkane(s) – conversion – – dehydrogenation 322–323 – – hydrocracking 320–321

– – hydroisomerization 319–320 – – naphtha reforming 321–322 – in crude oil 23 – hydrocracking of 445 – hydrodecyclization of 445 – hydroisomerization of 356–357, 445 – octane numbers of 256–257 – refining 585–586, 591–592 – – and motor-gasoline refining 518–519 alkene(s) 137–138, 147, 563 – to alcohol conversion by hydroformylation 466 – in aromatic alkylation – – cracking propensity of 397 – – phase behavior 397 – – pore size restrictions 397 – – reactivity of 396–397 – complete HYD 307 – composition, in alkene oligomerization 374–375 – conversion – – aliphatic alkylation 316–317 – – aromatic alkylation 317–319 – – double bond isomerization 312–314 – – metathesis 314 – – oligomerization 315–316 – – skeletal isomerization 314–315 – cyclization of 457 – disproportionation. see metathesis – hydration 309 – hydrogenation 213 – octane numbers of 257 – oligomerization 189–190, 190, 213 – – acidic resin catalysts 381–383 – – amorphous silica–alumina (ASA) 380–381 – – applications of 370–372 – – of broad cut of HTFT naphtha 228

Fischer–Tropsch Refining, First Edition. Arno de Klerk.  2011 Wiley-VCH Verlag GmbH & Co. KGaA. Published 2011 by Wiley-VCH Verlag GmbH & Co. KGaA.

604

Index alkene(s) (contd.) – – classic Whitmore-type carbocation mechanism 372 – – ester-based mechanism 372–373 – – free radical mechanism 373–374 – – heat management in 386 – – homogeneous nickel catalysts 383–384 – – H-ZSM-5 zeolite 378–380 – – organometallic insertion mechanism 373 – – SPA catalyst 375–378 – – syncrude process technology 385–388 – – thermal oligomerization 384–385 – and oxygenate recovery 587, 587 – partial HYD 306 alkene skeletal isomerization 354–356 alkyl aromatics 394 – cracking propensity of 397 alkylation 446 alkylperoxy radical (ROO) 478 α-value – of catalyst 78 – two, distribution 78 alumina (Al2 O3 ) – and attrition resistance 92 – pentene skeletal isomerization 359 η-alumina catalyst 203 American Hydrocol facility 141–151 – Fischer–Tropsch synthesis 143–145 – – gas loop 144 – – gas scrubber 144 – – oil scrubber 144 – Fischer–Tropsch refining 145–150 – – aqueous product 148–149 – – oil product 146–148 – refinery design 146, 146, 150–151 – syncrude – – branching 145 – – compound classes, distribution 145 – syngas production 142–143, 142 American Petroleum Institute (API) classification of lubricant base oils 584, 585 amides, in crude oil 25 amines, in crude oil 25 ammonia (NH3 ) 7 – in catalyst deactivation 90 amorphous metal oxide catalysts 341 amorphous silica–alumina (ASA), in alkene oligomerization 380–381 Anderson–Schulz–Flory (ASF) distribution 78, 79, 513, 542, 561 Anglo-Transvaal Consolidated Investment Company 153 aniline 401 antiknock behavior 33

aqueous product 114, 115, 151, 222, 565, 571 – diesel fuel and 565–566 – and motor-gasoline refining 517–518 – refining 136–137, 148–149, 166–169, 194–196, 196, 210–211, 225–226, 228 – – alcohol purification 168 – – chemical workup 167, 168 – – high-level options for 517 – – water-soluble oxygenates, composition 194 Arge LTFT oil refining 165–166, 165 – bauxite 166 – thermal cracking 166 – wax hydrogenation 166 Arge LTFT synthesis 159–161, 160 – compound classes 161 – gas loop 162 – syncrude composition 161 aromatic alkylation 317–319 – with C4 alkenes 401–403 – catalysis 396–397 – as conversion technology 393–395 – with ethene 397–399 – with heavy alkenes 401–403 – and isomerization 354 – with propene 399–401 – reaction chemistry of 395–396 – syncrude process technology 403–405 aromatic isomerization 354 aromatics 547, 563 – in crude oil 23 – octane numbers of 258 – production 586, 587, 595–596 – refining 595–596 aromatization 454, 460, 546 – catalysis 457–459 – reaction chemistry 456 – syncrude processing technology 460–461 aromax technology 450 ash content 66 ash fusion temperature 66 asphalt 35 asphaltene content in crude oil 28 associated gas 51 ASTM D 86 standard test method 260 ASTM D 323 standard test method 260 ASTM D 525 standard test method 261 ASTM D 613 standard test method 287, 296 ASTM D 873 standard test method 261 ASTM D 910 standard test method 264 ASTM D 975 specifications 285, 288 ASTM D 1322 standard test method 276 ASTM D 1655 standard 270, 271–272 ASTM D 2274 standard test method 294 ASTM D 2386 standard testing method 276

Index ASTM D 2500 standard test method 293 ASTM D 3241 standard test method 278 ASTM D 4625 standard test method 294 ASTM D 4809 standard test method 274 ASTM D 5001 standard test method 280 ASTM D 6079 standard test method 291 ASTM D 6468 standard test method 294 ASTM D 6890 standard test method 290 atmospheric distillation 44, 169, 170, 176, 178 atmospheric distillation unit (ADU) 521 atmospheric oxidation 136 attrition of catalysts 92 autoignition 253, 255, 256 – resistance 255, 258, 287 automobiles 32 autothermal reforming (ATR) technology 57, 58, 243, 244 autoxidation 58, 258, 294, 311–312, 466, 474, 479 – of distillate 567 – Fischer–Tropsch wax oxidation 480–484 – reaction chemistry 478–480 – regimes 477–478 – syncrude process technology 484–485 – of waxes 136 average branching number (ABN) 598 average carbon number (ACN) 598 aviation – gasoline 33, 35, 264–265 – – specifications 264 – turbine engines in 35 – turbine fuel 269 aviation bright stock 134

b ball-on-cylinder lubricity evaluator (BOCLE) 246 base oils. see lubricant base oils battlefield use fuel of the future (BUFF) 272, 280 bauxite 146–147, 147, 150, 166 Benfield CO2 removal process 185 benzene 262, 457 benzene, toluene, and the xylenes (BTXs) 43, 586 benzene–toluene–ethylbenzene–xylenes (BTEX) 586 benzonitrile 401 benzothiophene 401 bimolecular partial alcohol dehydration 336, 337 biomass derived feed, logistics and pretreatment 5 biomass-to-liquids (BTLs) process 3 blending octane number 256 boiler fuel 33 boiling range broadening 303 boiling ranges of crude oil 29–31

bond dissociation energies (BDEs) 410, 410, 412–413, 413 branched alkanes 273 – oligomerization process in 385–386 BritishGas/Lurgi (BGL) slagging gasifier 61 bromide ions, in catalyst deactivation 89–90 Brønsted acid-catalyzed alcohol dehydration, mechanism for 340 Brønsted acid–catalyzed processes 599 1,3-butadiene 588 butene 544 – isomerization catalysis 358–359, 362 butoxybutane 338

c C2 –C4 alkenes 43 C2 –C4 hydrocarbons – diesel fuel and 565 – jet fuel and 544–545 – and motor-gasoline refining 515–516 C2 –C4 selectivity 79 – and methane selectivity 98–99 C3 –C4 Crude LPG – refining 129–130 C5 –C6 naphtha 551–552 – hydroisomerization 360 – isomerization catalysis 362–363 C6 −C8 aromatics 43 C6 -cut 469 – preparation of 467–468 C7 naphtha – hydroisomerization 360 C8 -cut 470–474 C84/3 SPA catalyst 203 capital cost 17–19, 19 capital expenditure, minimizing 506 carbide mechanism, for chain growth 74 carbon deposition – and Co-LTFT catalyst deactivation 96 – and Fe-HTFT catalyst deactivation 93 – and methane selectivity 97 carbon dioxide (CO2 ) 7, 12 – removal of 67–69, 185 carbon efficiency 14, 15, 496 – and capital cost 18 – in German facilities 128, 128 carbon-efficient refining 304 carbon gasoline, refining 130–132 carbon number – and hydroisomerization technology 361–362 – -based refining 303 – – refinery design 500 carbon number broadening 228

605

606

Index carbon number distribution 561–562 – in alkene oligomerization 374 – and chain growth probability 78 – in oligomerization process 386 carbon rejection technology 210 carbon residue of crude oil 28 carbonates 258 carboxylic acids 137, 228, 480, 481, 588 – in aqueous products 167–168, 167 – in biomass refining 310 – in crude oil 26, 27 – leaching, and catalyst deactivation 92 Carthage Hydrocol Company 141 catalyst deactivation, Fischer–Tropsch 88–99 – Co-LTFT catalysts, deactivation of 95–99 – Fe-HTFT catalysts, deactivation of 93 – Fe-LTFT catalysts, deactivation of 93–95 – mechanical catalyst degradation 91 – metal carboxylate formation 90–91 – poisoning by syngas contaminants 89–90 – volatile metal carbonyl formation 90 catalyst formulation, Fischer–Tropsch – and product selectivity manipulation 81–83 – – bifunctionality 83 – – catalyst stability 82 – – hydrogenation activity 82 – – promoters, sensitivity to 82 – – support material 82 – – WGS activity 82 catalyst geometry, in alkene oligomerization 375 catalyst poisons, removal of 7 catalyst wax 124 catalyst(s) – nickel-based reforming 55 – selection 303 catalytic cracking 210, 407, 414–416, 421, 545–546 – catalysis 423–425 – syncrude processing technology 425–427 catalytic dewaxing 45 catalytic distillation 206 catalytic naphtha reformer 192–193 catalytic partial oxidation (CPO) 57 catalytic reforming technology 35 central luconia 231 cetane–density relationship of various compounds 564 cetane index 287 cetane number 42–43 – improvers 573 chain growth 74–76 – mechanistic representation of 74–75 – probability 78–80 – – C2 selectivity 79

– – methane selectivity 78 – – two α-value distribution 79 chain termination reactions 76 chemical absorption 68 chemical extraction 200–201, 213–214 chemicals 11–12 – coproduction, and motor-gasoline refining 514–515 – extraction from Fischer–Tropsch syncrude 465 – from gasification liquids 11 – synthesis from Fischer–Tropsch syncrude 465–466 chemicals and lubricant refining 581 – Fischer–Tropsch-based lubricant base oil refining 597 – – group III lubricant refining 598–599 – – group IV lubricant refining 599–600 – – lubricant base oil refining 600–601 – Fischer–Tropsch-based petrochemical refining 591 – – alkane refining 591–592 – – aromatics refining 595–596 – – light alkene refining 592–594 – – linear 1-alkene refining 594–595 – – oxygenate refining 596 – lubricant base oils 584–585 – petrochemicals 582–584, 582, 584 – syncrude, chemicals refining concepts for – – alkene and oxygenate recovery 587, 587 – – alkane-based refining 585–586 – – aromatics production 586, 587 – – fuels and chemicals coproduction 588–591 chemical technologies 465 – autoxidation 474 – – Fischer–Tropsch wax oxidation 480–484 – – reaction chemistry 478–480 – – regimes 477–478 – – syncrude process technology 484–485 – n-1-alkenes, production of 466 – – distillate-range n-1-alkene extraction 474 – – 1-octene, extraction of 470–472 – – 1-octene production from 1-heptene 473 – – 1-pentene and 1-hexene, extraction of 467–470 Chevron Nigeria 241–242 Chevron Phillips Chemical company 450 Chevron Texaco Isocracking 244 chloride ions, in catalyst deactivation 89–90 chlorination 134, 134 circulating fluidized bed (CFB) reactor 157–158, 183 – design 220 civilian turbine fuels 270 classic Whitmore-type carbocation mechanism, in alkene oligomerization 372 clay-treater 163, 164, 177

Index Clean Air Act 39, 41 closed gas loop design 107, 108–109 cloud point (CP) 293 coal 154 – carbonization of 120 coal liquids 138, 404, 568 coal oil 32 coal pyrolysis product refining 169–170, 170, 177, 196–198, 197, 211–212 – tar workup section products 198 coal-to-liquids (CTLs) 503 cobalt (Co) – hydrogenolysis 80–81 – see also catalyst formulation cobalt-based low-temperature Fischer–Tropsch (Co-LTFT) 8, 9, 10, 10, 11, 233, 234–235, 238, 239, 243–244 – catalyst 121 – – deactivation of 95–99, 99 coker gas 120 coking reaction 54, 326 cold condensate 115 cold filter plugging point (CFPP) 293 combined homo- and heterogeneous syngas production 57 completion, shortest time to 507–508 compression-ignition engines 283, 284, 288, 290 condensate 114 – cold 115 – hot 115 – refining 202–203 condensate oil, refining 132–135 ‘‘confinement’’ model 452 conformational isomerization 353 continuous catalyst regeneration (CCR) 192 continuous regenerative units 449 continuous stirred tank reactor (CSTR) 62, 85, 173 contractual obligations 508 conventional catalytic naphtha reforming 444, 445 – catalysis 447–449 – reaction chemistry 444–447 – syncrude processing technology 449–450 conventional crude oil 22–28 – hydrocarbons in 23 – metals in 26–27, 27 – nitrogen compounds in 24, 24 – oxygenates in 25–26, 26 – physical properties of 27–28 – sulfur compounds in 23–24, 24 – see also crude oil conversion of olefins to distillates (COD) technology 222 – in alkene oligomerization 379

conversion process 33 co-refining – diesel fuels 567–569 – jet fuel 547–548 – and motor-gasoline refining 521–522 Co–ThO2 –kieselguhr catalyst – product yield, pressure effect on 125 Co–ThO2 –MgO–kieselguhr catalyst – distillate fractions, comparison 133 cracking 356, 407, 445 – catalytic cracking 421 – – catalysis 423–425 – – syncrude processing technology 425–427 – hydrocracking 427 – – catalysis 430–434 – – syncrude processing technology 434–436 – and isomerization 354 – rate of 415 – reaction chemistry 410 – – catalytic cracking 414–416 – – hydrocracking 416–419 – – thermal cracking 410–414 – of slack wax fraction 135 – thermal cracking 419 – – syncrude processing technology 421 creosote hydrotreater 197–198 crude oil 10, 492 – density of 27 – -derived diesel fuel 567 – -derived kerosene and Fischer–Tropsch kerosene, blending 548 – global consumption of 31 – price 16 – products from 28–31 – residue, classification of 28 – vs. syncrude, comparison 12–13, 13 – see also conventional crude oil crude oil refining/refineries 409 – conventional crude oil 22–28 – – products from 28–31 – evolution of 31–45 – – first generation 32–33 – – fourth generation 39–43, 40 – – lubricant base oil refineries 44–45 – – petrochemical refineries 43–44 – – second generation 33–35, 34, 36 – – third generation 36–39, 38 – fluid catalytic cracking 323 – naphtha reforming 321–322 – and oligomerization 315–316 – thermal cracking 324–325 cryogenic separation 106 cumene 258 cyclar process 458

607

608

Index cyclic units 449 cycloalkane(s) 273, 457, 547, 563 – in crude oil 23 – direct dehydrogenation of 445 – hydrocracking of 445 – hydroisomerization of 445 – octane numbers of 258 – synthesis 567 cyclohexane 457 cyclohexene 457 cyrogenic separation 110–111, 111

d Dakota Gasification Company 52 De Meern 243 decanted oil (DO) 113, 178 DEF STAN 91–91 specifications 270, 272, 279 dehydration 336–339 – and alkene dimerization 339 – catalysis 340–341 – reaction chemistry 339–340 – syncrude process technology 341–342 density–cetane–yield triangle 563–564, 569–570 desorption 76, 83 – vs. hydrogenation 80–81 devolatilization 59 diamond gas holdings 231 1,2-dibromoethane 264 diesel fuel 33, 41–42, 132, 133, 138, 148, 283 – additives affecting refinery design 295–296 – boiling range of 562 – future specification changes 296–297 – production 571 – properties 171, 208, 286 – – aromatic content 292 – – cetane number 286–290 – – cold-flow properties 293 – – density and viscosity 290 – – elastometer compatibility 294–295 – – flash point 290 – – lubricity 290–292 – – stability 294 – – sulfur content 292–293 – residue and wax, 565 – specifications 284–285, 560–561 – – American and European 284 – see also jet fuels diesel fuel refining 559 – application of lever rule to 570 – decisions affecting 564 – – aqueous product 565–566 – – C2 –C4 hydrocarbons 565 – – co-refining 567–569

– – density–cetane–yield triangle, dealing with 569–570 – – residue and wax 565 – – technology selection 566–567, 566 – gap analysis for syncrude to diesel fuel 560 – – carbon number distribution 561–562 – – composition and quality 562–563 – – density–cetane–yield triangle 563–564 – – diesel fuel specifications 560–561, 560 – heavy. see heavy diesel fuel – from HTFT syncrude 570–573, 571, 572 – from LTFT syncrude 573–578, 574, 575, 577 – light. see light diesel fuel – refinery design 574 dimerization 356, 445 Dimersol E unit 203 direct alcohol dehydration 336 disproportionation 446 distillate 33 distillate hydrotreater (DHT) 192, 193, 217, 225 distillate-range n-1-alkene extraction 474 distillate-selective cracker (DSC) 192, 194 distillation – atmospheric 44 – broadening 192 – fractions of crude oil 30 – profile – – and crude oil classification 22 – – of motor-gasoline 260 – vacuum 36, 38, 44 di-tert-butyl peroxide (DTBP) 475 double bond isomerization 353 driveability index (DI) 260 dry ash moving bed gasification 61 dry-feed entrained flow gasification 65 drying 58 Dual fuel 207

e E-factor 496 efficiency factor (EF) 496 electricity, export of 16 Emergency Petroleum Allocation Act 38 energy efficiency. see thermal efficiency entrained flow gasifiers 64–66 environmental footprint, smallest 507 E-point terminology 260 Escravos GTL facility 17 ester(s) 480 – -based lubricants 598 – -based mechanism, in alkene oligomerization 372–373 – in crude oil 26 ethanal 211

Index ethane 110, 545 ethanoic acid (acetic acid) 476 ethene 43, 203, 549, 588 – in aromatic alkylation 397–399 – in HTFT synthesis 393 etherification 289, 343–344 – catalysis 346 – reaction chemistry 345–346 – syncrude process technology 347 2-ethoxy-2-methylbutane (TAEE) 345 2-ethoxy-2-methylpropane (ETBE) 345 ethyl ethanoate 211 ethylbenzene 586 – production 399 – – catalysts used in 398 European Union (EU) fuel specifications existing gum 261 external recycle 108, 108 ExxonMobil 241

252

f fatty acid methyl esters (FAMEs) 297, 560–561, 568, 569 feed – cost 14–15 – description 497 – diversity 4 – flexibility 4 – selection 14, 15 feed-to-electricity conversion 16 feed-to-liquids (XTLs) conversion 3 – and power generation 16 feed-to-syngas conversion 4–8 – feed, logistics and preparation of 5, 5 – syngas cleaning and conditioning 7–8, 8 – syngas production 5–7 ferrierite, pentene skeletal isomerization 359 fifth column 176 final boiling point (FBP), of motor-gasoline 262 first generation crude oil refineries 32–33 first-generation intermediates 583 Fischer, Franz 73 Fischer–Tropsch distillate 559, 567–568 Fischer–Tropsch facilities 3–19 – feed-to-syngas conversion 4–8 – – feed, logistics and preparation of 5, 5 – – syngas cleaning and conditioning 7–8, 8 – – syngas production 5–7 – indirect liquefaction economics 14–19 – – capital cost 17–19, 19 – – feed cost 14–15 – – product pricing 15–16 – syncrude-to-product conversion 10–13 – – fuels versus chemicals 11–12

– – upgrading and refining 10–11 – syngas-to-syncrude conversion 8–10 Fischer–Tropsch refining/refinery 222, 303, 541 – alcohol dehydration in, applications of 336–339 – alkene oligomerization 369 – American Hydrocol facility 145–150 – – aqueous product 148–149 – – oil product 146–148 – aqueous product refining 225–226, 247 – Bintulu GTL – – aqueous product treatment 238 – – oil refining 235–238 – chemical addition 328 – cost of 304 – energy requirements 328 – evaluated technologies for 327–328 – German 128–137 – – aqueous product 136–137 – – C3 –C4 Crude LPG 129–130 – – carbon gasoline 130–132 – – condensate oil 132–135 – – waxes 135–136 – oil refining 222–225, 244–246 – oligomerization, applications of 315–316 – Sasol 1 facility 163–171, 163, 174–177, 175 – – aqueous product refining 166–169 – – Arge LTFT oil refining 165–166 – – coal pyrolysis product refining 169–170 – – Kellogg HTFT oil refining 163–165 – – synthetic fuel properties 170–171 – – tar workup 161 – Sasol 2 and 3 facilities 186–199 – – aqueous product refining 194–196 – – coal pyrolysis product refining 196–198 – – synthetic fuel properties 198 – – synthol HTFT condensate refining 188–192, 189 – – synthol HTFT oil refining 192–194 – syncrude compatibility 326 – synthetic fuel properties 227 – waste generation 326, 328 – see also industrial Fischer–Tropsch facilities Fischer–Tropsch syncrude 244, 256–258, 261, 263, 276, 278, 279, 286, 289, 290–292, 562 – oxygenate refining technologies 335 Fischer–Tropsch synthesis 73–99, 201–202, 220, 243–244 – American Hydrocol facility 143–145 – – syncrude composition 144 – Bintulu GTL 233–235 – catalyst deactivation 88–99 – – Co-LTFT catalysts, deactivation of 95–99 – – Fe-HTFT catalysts, deactivation of 93 – – Fe-LTFT catalysts, deactivation of 93–95 – – mechanical catalyst degradation 91

609

610

Index Fischer–Tropsch synthesis (contd.) – – metal carboxylate formation 90–91 – – poisoning by syngas contaminants 89–90 – – volatile metal carbonyl formation 90 – gas loop design 221–222 – in German facilities 121–128 – – carbon efficiency 128 – – gas loop design 127–128 – – medium-pressure synthesis 125–127 – – normal-pressure synthesis 122–124, 123 – mechanism 74–77 – – carbide 74 – – oxygenate 75, 76, 76 – product selectivity 77–81 – – chain growth probability 78–80 – – hydrogenation vs. desorption 80–81 – – manipulation 81–88 – – readsorption chemistry 81 – Sasol 1 facility 157–162, 173–174 – – Arge LTFT Synthesis 159–161 – – gas loop design 162 – – Kellogg HTFT synthesis 157–159 – Sasol 2 and 3 facilities 183–186 – – gas loop design 184–186, 185 – – syncrude composition 184 Fischer–Tropsch wax oxidation 480–484 fixed bed reactors 85 fluid catalytic cracking (FCC) 407, 422, 444, 517, 589 – in crude oil refining 323 – and thermal cracking 324–325 fluid hydroforming 444 fluidized bed gasifiers 62–63, 85, 142 fouling – of Co-LTFT catalysts 96 – of Fe-HTFT catalysts 93 fourth generation crude oil refineries 39–43, 40 free radical mechanism, in alkene oligomerization 373–374 freezing point 276 Friedel–Crafts alkylation 395 fuel ethers 262–263 – properties of 338 fuel(s) 11–12, 29, 32 – blending flexibility, in aromatic alkylation 394 – and chemicals coproduction 588–591 – quality 200 furans, in crude oil 26 fused-iron catalyst 153, 184

g gap analysis – for syncrude to diesel fuel 560 – – carbon number distribution 561–562 – – composition and quality 562–563

– – density–cetane–yield triangle 563–564 – – diesel fuel specifications 560–561 – for syncrude to jet fuel 541 – – carbon number distribution 542 – – composition and quality 542–544 – – jet fuel specifications 541–542 – for syncrude to motor-gasoline 510 – – carbon number distribution 510–511 – – composition and quality 511–514 – – motor-gasoline specifications 510 gas cleaning, natural gas 54, 55 gas hourly space velocity (GSHV) 122 gasification 6, 58 – classification of 6 – of heteroatoms 59–60 – high-temperature entrained flow gasification 64–66 – low-temperature moving bed gasification 60–62 – medium-temperature fluidized bed gasification 62–63 – technologies, selection/comparison 66 gas liquor 67 gas loop, Fischer–Tropsch 105–115 – configurations 107–109 – – closed gas loop design 107, 108–109 – – open gas loop design 107–108, 107 – design 69, 221–222 – – in German facilities 127–128 – – Sasol 1 facility 162, 162 – – Sasol 2 and 3 facilities 184–186, 185 – syncrude, cooling and separation 109–115 gas oil and heavier material 547 gaseous hydrocarbons 35 gas reforming 53, 57, 109 – technologies, comparison of 58 gas-to-liquids (GTLs) process 52, 142, 231 – Fischer–Tropsch refining, in Bintulu GTL – – aqueous product treatment 238 – – oil refining 235–238 – Fischer–Tropsch synthesis, in Bintulu GTL 233–235 – Oryx 241–248 – Pearl GTL facility 238 – syngas production in Bintulu GTL 232–233 generic Fischer–Tropsch refinery configuration 562 gasoline 32, 138 – aviation 33, 35 German Fischer–Tropsch facilities 119–138, 120 – Fischer–Tropsch refining 128–137 – – aqueous product 136–137 – – C3 –C4 Crude LPG 129–130 – – carbon gasoline 130–132 – – condensate oil 132–135 – – waxes 135–136

Index – refinery design 137–138 – syngas production 119–121, 121 – Fischer–Tropsch synthesis 121–128 – – carbon efficiency 128 – – gas loop design 127–128 – – medium-pressure synthesis 125–127 – – normal-pressure synthesis 122–124, 123 gums 261

h H2:CO ratio 5, 84, 87 Haag–Dessau mechanism 414 halogen-containing compounds, gasification of 60 heavier alkanes, hydroisomerization 360, 364 heavy diesel fuel 132 – properties 133 heavy end recovery stream 244 heavy paraffin synthesis (HPS) 234 heavy vacuum gas oil (HVGO) 193 1-heptene, extraction 204, 205, 467–470, 468 heptoxyheptane 338 heteroatoms – and crude oil classification 23 – gasification of 59–60 – removal of 4 heterogeneous syngas production 57 hexoxyhexane 338 high-temperature entrained flow gasification 64–66, 65 – dry-feed entrained flow gasification 65 – performance of 65 – slurry-feed entrained flow gasification 65–66 high-temperature Fischer–Tropsch (HTFT) process 143m 258, 262, 271, 272, 279, 289, 293–295, 304, 305, 544, 583, 586, 590 –592 – distillate 559 – product 109 – syncrude refining 339, 563 – – co-refining 569 – – diesel fuel refining from 570–573 – – jet fuel refining from 548–553 – – recovery 113–114, 113 high-temperature fluid catalytic cracker (FCC) 209 high-temperature gasification 6, 7 high-temperature water gas shift 69 high-vacuum distillation 176–177 Hoesch facility 136 homogeneous gasification 57 homogeneous nickel catalysts, in alkene oligomerization 383–384 homogeneous syngas production 57 homolytic bond dissociation 411 hot condensate 115 hot gas recycle process 142

hydration 129, 130, 347–349 – catalysis 349–350 – reaction chemistry 349–348 – syncrude process technology 350 hydride transfer 415 hydrocarbon autoxidation, reaction network of 480 hydrocarbon class, and crude oil classification 22 hydrocarbon compounds, cetane numbers of 288 Hydrocarbon Research Inc. 141 hydrocarbons 278 – in crude oil 23 – gaseous 35 – vs. oxygenates, boiling point difference 112 hydrocarbons, light 546 – yield of 593 Hydrocol process 141 hydrocracking 235–236, 244–246, 320–321, 408, 409, 416–419, 420, 427, 428, 446, 545, 547, 548, 565 – catalysis 430–434 – and hydroisomerization 360 – ideal 432 – nonideal 432 – syncrude processing technology 434–436 hydrodearomatization (HDA) 198, 305, 597 hydrodemetallization (HDM) 306 hydrodenitrogenation (HDN) 306 hydrodeoxygenation (HDO) 192, 224, 306, 307–308 hydrodesulfurization (HDS) 306 hydroformylation, alkene to alcohol conversion by 135, 466 hydrogen cyanide (HCN), in catalyst deactivation 90 hydrogenated motor-gasoline, alkene oligomerization 377 hydrogenation (HYD) 74–76, 189, 190, 190 – of alkenes 305 – vs. desorption 80–81 – wax 166 hydrogenolysis 80–81, 445 hydrogen sulfide (H2 S) 183 – in catalyst deactivation 89 – emissions, reducing 172 – removal of 67–69 hydroisomerization 319–320, 354, 360–362 – butane hydroisomerization catalysis 362 – C5 –C6 naphtha isomerization catalysis 362–363 – heavy alkane hydroisomerization catalysis 364 – syncrude process technology 364–366 – wax hydroisomerization catalysis 364 hydroperoxides 255, 294, 478 hydrotreater 236, 246 hydrotreating 169–170, 305–306 – alkenes, hydrogenation of 306–307 HZ-1 catalyst 191

611

612

Index H-ZSM-5, 457–458, 565 – aromatization over 454, 457 – -derived oligomer stream 571 H-ZSM-5 zeolite catalyst 224 – in alkene oligomerization 378–380

i ignition improvers 296 ignition quality tester (IQT) 287 income. see product pricing indirect alkylation 371 indirect liquefaction 3, 3 – economics 14–19 – – capital cost 17–19, 19 – – feed cost 14–15 – – product pricing 15–16 indole 401 industrial Fischer–Tropsch facilities 303 – see also Fischer–Tropsch refinery inerts, concentration of – in alkene oligomerization 375 integrated crude oil and Fischer–Tropsch refinery 568 internal recycle 108, 108, 128 iron (Fe) – hydrogenolysis 80–81 – see also catalyst formulation iron-based high-temperature Fischer–Tropsch (Fe-HTFT) synthesis 8, 9, 10, 141, 143–144 – catalysts 221 – – deactivation of 93 – industrial, selectivity change during 94 iron-based low-temperature Fischer–Tropsch (Fe-LTFT) synthesis 8, 9, 10 – catalysts, deactivation of 93–95, 96 isomerization – aromatic isomerization 354 – conformational isomerization 353 – double bond isomerization 353 – hydroisomerization 354 – skeletal isomerization 353–354 – stereochemical isomerization 353 isoparaffinic kerosene (IPK) 212, 272, 279, 542, 545

j Jet A-1 specifications 541, 542 jet fuel refining 541 – decisions affecting 544 – – C2 –C4 hydrocarbons, fate of 544–545 – – co-refining 547–548 – – residue and wax, fate of 545–546 – – technology selection 546–547, 546 – gap analysis for syncrude to jet fuel 541 – – carbon number distribution 542

– – composition and quality 542–544 – – jet fuel specifications 541–542 – from HTFT syncrude 548–553, 549, 551, 553 – from LTFT syncrude 553–557 jet fuels 269, 286, 574 – production 561 – properties 273–274 – – aromatic content and smoke point 276, 278 – – density and viscosity 275–276 – – elastometer compatibility and lubricity 279–280 – – freezing point temperature 276 – – net combustion heat 274–275 – – stability 278–279 – – sulfur and acid content 278 – – volatility 278 – specifications 270–271 – – fuel for military use 272–273 – – future changes 280 – – synthetic jet fuel 271–272, 274 – see also diesel fuel jet propulsion (JP) aviation turbine fuels, United States military 273 JGC Corporation 231 JP-8 military jet fuel, Fischer–Tropsch-derived 542

k KBR Superflex Selective Catalytic Cracking (SCC) technology 210 Kellogg HTFT oil refining 163–165, 164 – clay-treater 163, 164 – oligomerization 163, 164–165 Kellogg HTFT synthesis 157–159, 157 – compound classes 159 – gas loop 162 – product distribution 159 kerosene 32, 547 – crude-oil-derived 548 kerosene cut 225 kerosene range product – from SPA-catalyzed oligomerization 377 ketone(s) 77, 258, 588 – as primary autoxidation products 480 Keyes process 168 kogasin I 132 kogasin II 132 – conversion into lubricating oil 134 K¨olbel–Engelhardt-type synthesis 586

l lamp oil. see kerosene lead bromide 264 lead oxybromides 264 least refinery ‘‘complexity’’ light alcohols 339

507

Index light alkenes 43 – refining 592–594 light aromatics 43 light diesel fuel 132 – properties 133, 148 light oil 114 light vacuum gas oil (LVGO) 193 linear 1-alkene(s) 588 – extraction of 204–205 – refining 594–595 linear alkyl benzene (LAB) synthesis 567 linear hydrocarbons 562 liquefied natural gas (LNG) 218, 231 liquid absorption 68 – chemical absorption 68 – physical absorption 68 liquid petroleum gas (LPG) 35, 124, 443, 455, 555, 585 low aromatic distillate (LAD) range of products 227 low-complexity refinery design 509 low-temperature Fischer–Tropsch (LTFT) process 231, 235, 243, 244, 258, 262, 288, 290, 293, 294 – distillate 559 – jet fuel refinery design 574, 576, 578 – refinery 305 – syncrude 544, 583 – – diesel fuel refining from 573–578 – – jet fuel refining from 553 – – product 109 – – recovery 114–115, 115 – – refining 339 low-temperature gasification 6–7, 6 low-temperature moving bed gasification 60–62, 61 – dry ash moving bed gasification 61 – feed requirements and product composition, comparison 62 – slagging moving bed gasification 61–62 low-temperature water gas shift 69 lubricant base oil refining/refineries 44–45, 597 – group III lubricant refining 598–599 – group IV lubricant refining 599–600 – lubricant base oil refining 600–601 – solvent-based 45 lubricant base oils 29, 134, 584–585 lubricating oil 134 – properties 134 Lurgi dry ash coal gasification – Sasol 1 facility 154–155, 155 – – ash disposal 154 – Sasol 2 and 3 facility 182 Lurgi dry ash moving bed gasifier 61 Lurgi Mark I coal gasifiers 154 Lurgi Mark IV gasifier 182

Lurgi Mark V coal gasifiers 172 Lurgi Mark VI coal gasifiers 172

m magnesium oxide 121 maximum liquid product volume 507 maximum motor-gasoline refinery design 509 mechanical catalyst degradation 92 medium-pressure synthesis, German 125–127, 126 – product distribution 127 – RON, MON and density of naphtha 131 medium-temperature gasification 6, 7 – fluidized bed gasification 62–63, 63 – – performance data of 64 mercaptans. see thiols ‘‘mersol’’ detergents 135 metal carbonyl compounds formation, and catalyst deactivation 90, 90 metal carboxylates 228 – formation, and catalyst deactivation 91–92, 94 – – hydrogenation 92 – – thermal decomposition, onset of 91 metals – in crude oil 26–27, 27 – gasification of 60 – hydrogenolysis 80–81 metathesis, in alkene conversion 314 methanation 56 methane 110 – selectivity 78 – – and C2-C4 selectivity 98–99 2-methoxy-2-methylbutane (TAME) 345 2-methoxy-2-methylpropane (MTBE) 259, 263, 345 methoxymethane (dimethyl ether, DME) 289 methyl aryl ethers 258 methylcyclopentadienyl manganese tricarbonyl (MMT) 207, 252 methylene chain index 599, 599 methyl tertiary butyl ether (MTBE) 41, 520 MFI-type zeolite 565 M-forming processes 454, 455, 455 mineral rejection 4 Mitsubishi Corporation 231 mixed paraffins 585 mobil olefins to gasoline and distillate (MOGD) process 224 Mossgas facility 217 – discussion of refinery design 228–229 – Fischer–Tropsch refining 222 – – aqueous product refining 225–226 – – oil refining 222–225 – – synthetic fuel properties 227 – Fischer–Tropsch synthesis 220

613

614

Index Mossgas facility (contd.) – – gas loop design 221–222 – PetroSA facility, evolution of 227 – – changes in Fischer–Tropsch refinery 227–228 – – low-temperature Fischer–Tropsch synthesis, addition of 227 – syngas production 218 – – gas reforming 218–220 – – natural gas liquid recovery 218 motor gasoline (petrol) 33, 35, 145, 147, 150, 171, 213, 251, 283, 285 – components, properties of 42 – composition changes in 35, 36 – high-octane 39, 40 – leaded 207 – properties of 41, 148, 208 – – alkene content 261 – – aromatic content 262 – – aviation gasoline 264–265 – – density 259 – – fuel stability 261 – – metal content 263 – – octane number 253–259 – – oxygenate content 262–263 – – sulfur content 262 – – volatility 259–260 – RON, MON and density in Sasol 1 refinery 171 – specifications 252–253, 253, 512 – – future changes 265–266 motor-gasoline refining 509 – decisions affecting 514 – – alkane-based naphtha refining 518–519 – – aqueous product 517–518 – – C2 –C4 hydrocarbons 515–516 – – chemicals coproduction 514–515 – – co-refining 521–522 – – residue and wax 516–517 – – technology selection 519–521 – gap analysis for syncrude to motor-gasoline 510 – – carbon number distribution 510–511 – – composition and quality 511–514 – – motor-gasoline specifications 510 – from HTFT syncrude 522–529, 523, 524, 527, 528 – from LTFT syncrude 529–539, 530, 532, 534, 536, 537, 538 – and syncrude refinery designs 511 – technology map for 519 motor octane number (MON) 131, 171, 255, 287

n n-1-alkenes 513, 595 – applications of 466 – extraction 204 – production of 466

– – 1-octene, extraction of 470–472 – – 1-octene production from 1-heptene 473 – – 1-pentene and 1-hexene, extraction of 467–470 – – distillate-range n-1-alkene extraction 474 n-alkanes 585 – hydrocracking of 418 naphtha 547 – reforming 513 – – thermal 443–444 – see also gasoline naphtha hydrotreater (NHT) 192, 193, 224 naphthenic acids, in crude oil 26 natural gas 51–52, 231, 242–243 – composition 52 – logistics and pretreatment 5 – syngas production from 53–58, 54, 142–143, 144 – – adiabatic oxidative reforming 56–57 – – adiabatic prereforming 55–56 – – gas cleaning 54, 55 – – gas reforming technologies, comparison 57, 58 – – steam reforming 56 natural gas liquid (NGL) 51, 217, 232 – recovery 218 natural gasoline 147 n-butane 222 – aromatization of 459 – hydroisomerization 360 net present value (NPV), maximizing 507 neutral trialkyl phosphate esters 598 Ni/SiO2 –Al2 O3 catalyst 226 nickel (Ni) – -based reforming catalysts 55 – in crude oil 26 Nigerian National Petroleum Company 241 nitrogen – -based chemicals 11 – compounds – – in catalyst deactivation 90 – – in crude oil 24, 24 – gasification of 60 N-methyl-2-pyrrolidone (NMP) 469, 469 N-methyl pyrrolidone (NMP) extraction 204 nonacid chemicals, in aqueous products 166–167, 167 nonassociated gas 51 normal-pressure synthesis, German 122–124, 123, 138 – aliphatic hydrocarbons, composition 125 – product distribution 127 – RON, MON and density 131 – syncrude fractions, composition 124 nuclear magnetic resonance (NMR) spectrometry 288

Index

o octane number 33 1-octene, extraction 204–205, 470–472, 471, 472, 473 octoxyoctane 338 oil circulation process 142 oil crisis 36–37, 37, 181 oil refining 146–148, 205–210, 222–225 olefinic motor-gasoline, from phosphoric acid-catalyzed oligomerization 376 olefinic naphtha 224 oligomerization 129–130, 134, 134, 147, 150, 163, 164–165, 189–190, 190, 202, 203, 565 – acid-catalyzed 388 – in alkene conversion 315–316 – and isomerization 354 – technology, selection 567 open gas loop design 107–108, 107 operating conditions, Fischer–Tropsch – and product selectivity manipulation 83–84, 83 – – catalyst activation 84 – – pressure 84 – – space velocity 84 – – syngas composition 84 – – temperature 83–84 organic acids, in crude oil 26 organic sulfur, in catalyst deactivation 89 Organization of Petroleum Exporting Countries (OPEC) 37 organometallic insertion mechanism, in alkene oligomerization 373 Oryx and Escravos gas-to-liquids 241, 242 – Fischer–Tropsch refining in – – aqueous product treatment 247 – – oil refining 244–246 – refinery design discussion 247–248 – syngas production in 242–243 – Fischer–Tropsch synthesis 243–244 Oryx GTL facility 17 oxidation 59 – atmospheric 136 – and Co-LTFT catalyst deactivation 97–98, 98 – and Fe-HTFT catalyst deactivation 93 – and Fe-LTFT catalyst deactivation 94–95, 94 – stability 261 ‘‘OXO’’ process 135 oxygen, addition and removal of – autoxidation 311–312 – carbonyl aromatization 310, 311 – dehydration 308–309 – esterification of 310 – etherification 309 – hydration of 309 – hydroformylation 311

oxygenate mechanism 76, 76 – for chain growth 75 oxygenate partitioning 111–113, 111 oxygenate refining 335, 596 oxygenated gasoline 41 oxygenates 138, 149, 459, 544, 587, 563 – in alkene oligomerization 375 – in crude oil 25–26, 26 – vs. hydrocarbons, boiling point difference – octane numbers of 258–259 – readsorption 76–77 – in SPA oligomerization 378

112

p P. C. Keith of Hydrocarbon Research Inc. 153 paraffins 176 – reformer plant 166 – waxy 135 Paraformer 166 partial oxidation (POX) processes 57, 58 partial refining 11 particle size distribution 66 particulate matter (PM) emissions 286, 289, 292 ‘‘peak oil’’ 37 Pearl GTL project 232, 238 1-pentene, extraction of 467–470 pentene isomerization catalysis 359–360 pentene skeletal isomerization 206 pentoxypentane 338 per pass conversion 105, 106 Perco-process 147 permanent gases 11 petrochemical refining/refineries 43–44, 591 – alkane refining 591–592 – aromatics refining 595–596 – light alkene refining 592–594 – linear 1-alkene refining 594–595 – oxygenate refining 596 – stand-alone 44 petrochemicals 29, 582–584, 582, 584 Petroleum Oil and Gas Corporation of South Africa (PetroSA) 217 Petronas 231 PetroSA facility, evolution of 227 – changes in Fischer–Tropsch refinery 227–228 – low-temperature Fischer–Tropsch synthesis, addition of 227 phenolic compounds 132 phenols 278–279 – in crude oil 26 Phenosolvan process 169, 196 Philips Petroleum Company 141 phosphoric acid oligomerization 130, 147, 150, 552 physical absorption 68

615

616

Index platforming 444 platinum-based catalysts 447 plug flow reactors (PFRs) 85 poisoning by syngas contaminants, and catalyst deactivation 89–90 polyalphaolefin (PAO) 585 Polyhydrotreater 190, 207 polyinternalolefin (PIO) 585 Polymer Corporation 164 polymer gasoline 147, 170, 370 potential gum 261 pour points of crude oil 27–28 powered flight 33 precipitated-iron catalysts 159, 160 prereforming 54, 243 – adiabatic 55–56 pressure separation 110 pressure swing absorption (PSA) 243 primary design objective 501 product description 497 product fractionation, after alkene oligomerization 388 product pricing 15–16 product selectivity, Fischer–Tropsch synthesis 77–81 – chain growth probability 78–80 – hydrogenation vs. desorption 80–81 – manipulation 81–88 – – catalyst formulation 81–83 – – operating conditions 83–84 – – reaction engineering 84–88 – readsorption chemistry 81 products – from crude oil 28–31 – – quality and boiling range 29–31 – recovery 106 – – see also syncrude, cooling and separation – of refining 21–22 Project Turbo 207 propane, aromatization of 459 propanoic acid (propionic acid) 476 propene 43, 202, 544, 588 – in aromatic alkylation 399–401 proton transfer 415 Pt/L-zeolite naphtha reforming, monofunctional nonacidic 450 – catalysis 452–453 – reaction chemistry 451–452 – syncrude processing technology 453–454 pyridine 401 – in crude oil 25 pyrolysis 7, 58–59 pyrroles, in crude oil 25

q Qatar Petroleum 241

r raw materials – crude oil refining 21 – for syngas production 51–53 reaction engineering, Fischer–Tropsch – and product selectivity manipulation 84–88 – – catalyst mechanical strength 86 – – catalyst replacement 86 – – catalyst–product separation 87 – – heat transfer 86 – – mass transfer 86 – – per pass conversion 87 – – reaction phase 85–86 – – reactor configuration 87–88 – – reactor type 85, 85 – – scale-up issues 88 – – syngas production upsets 88 reaction mechanism, in alkene oligomerization 375 reaction water 114, 115 reactivity, gasification 66 readsorption – chemistry 81 – of oxygenates 76–77 real-world refinery design 500 – refinery feed selection 502–503 – refinery location 503–506, 504 – – climate 504 – – environmental sensitivity 504–505 – – geology 504 – – intellectual property 506 – – legislation 505 – – location factor 505 – – marketing logistics 505–506 – – natural resources 504 – – politics and governance 505 – – utility access 505 – refinery products and markets 501–502 – refinery type 501 – secondary design objectives 506–508 rectisol naphtha 156 rectisol syngas cleaning 155–156 – fine wash 156 – main wash 156 – prewash 156 refinery benzene levels – in aromatic alkylation 393–394 refinery design 491, 569 – American Hydrocol facility 150–151 – in Bintulu GTL 239 – concepts – – characteristic of refining business 491–493

Index – – complex systems and design rules 493–495 – – refining complexity 495–496 – – refining efficiency 496 – conceptual 497 – – carbon-number-based design 499–500 – – hierarchical design 498 – – linear programming 497–498 – – technology preselection 498–499 – German facility 137–138 – Mossgas facility 228–229 – Oryx 247–248 – principles of 492 – for producing motor-gasoline and jet fuel 559 – real-world refinery design 500 – – refinery feed selection 502–503 – – refinery location 503–506 – – refinery products and markets 501–502 – – refinery type 501 – – secondary design objectives 506–508 – robust and flexible 509 – Sasol 1 facility 177–178 – Sasol 2 and 3 facilities 212–214 – strategy 576 refinery flexibility 507 refining/refineries 21–45, 497 – components of 21, 22 – crude oil vs. syncrude 12–13, 13 – partial 11 – process 21 – stand-alone 11 – see also crude oil refining/refineries reforming 59, 441 – aromatization 454 – – catalysis 457–459 – – reaction chemistry 456 – – syncrude processing technology 460–461 – conventional catalytic naphtha reforming 444 – – catalysis 447–449 – – reaction chemistry 444–447 – – syncrude processing technology 449–450 – and isomerization 354 – monofunctional nonacidic Pt/L-zeolite naphtha reforming 450 – – catalysis 452–453 – – reaction chemistry 451–452 – – syncrude processing technology 453–454 – thermal naphtha reforming 443–444 reformulated gasoline (RFG) 41 rehydrogenation, of Co-LTFT catalysts 97–98, 98 Reid vapor pressure (RVP) 260, 273 rejuvenation 123–124 religious engineering 494 research octane number (RON) 131, 255–257, 264

residue and wax – diesel fuel and 565 – jet fuel and 545–546 – and motor-gasoline refining 516–517 – see also wax(es) residue conversion – catalytic cracking 323–324 – coking 326 – Fischer–Tropsch refining technology selection 326–327 – thermal cracking 324–325 – visbreaking 324 residue oil 197 residue upgrading capacity 36, 38 retrograde condensation reactions 59 Ribblett ratio 87 Roelen, Otto 121 RZ-Platforming technology from UOP 450

s Sarawak State Government 231 Sasol 1 facility 153–178 – evolution of 172–177 – – coal pyrolysis product refining, changes in 177 – – Fischer–Tropsch refining, changes in 174–177 175 – – Fischer–Tropsch synthesis, changes in 173–174 – – syngas production, changes in 172 – Fischer–Tropsch refining 163–171, 163 – – aqueous product refining 166–169 – – Arge LTFT oil refining 165–166 – – coal pyrolysis product refining 169–170 – – Kellogg HTFT oil refining 163–165 – – synthetic fuel properties 170–171 – Fischer–Tropsch synthesis 157–162 – – Arge LTFT Synthesis 159–161 – – gas loop design 162 – – Kellogg HTFT synthesis 157–159 – refinery design 177–178 – syngas production 154–156 – – Lurgi dry ash coal gasification 154–155 – – rectisol syngas cleaning 155–156 Sasol 2 and 3 facilities 181–214 – Fischer–Tropsch refining 186–199 – – aqueous product refining 194–196 – – coal pyrolysis product refining 196–198 – – synthetic fuel properties 198 – – synthol HTFT condensate refining 188–192, 189 – – synthol HTFT oil refining 192–194 – Fischer–Tropsch synthesis 183–186 – – gas loop design 184–186, 185 – – syncrude composition 184 – refinery design 212–214 – Sasol synfuels, evolution of 199–212

617

618

Index Sasol 2 and 3 facilities (contd.) – – coal pyrolysis product refining, changes in 211–212 – – Fischer–Tropsch aqueous product refining, changes in 210–211 – – Fischer–Tropsch condensate refining, changes in 202–203 – – Fischer–Tropsch oil refining, changes in 205–210 – – Fischer–Tropsch synthesis, changes in 201–202 – – linear 1-alkenes, extraction of 204–205 – – syngas production, changes in 201 – – synthetic jet fuel 212 – syngas production 182–183, 183 – – Lurgi dry ash coal gasification 182 – – syngas cleaning 182–183 Sasol 2 expansion project 181 Sasol Advanced Synthol (SAS) 173, 220 – fixed fluidized bed reactor 201, 201 Sasol Clean Air Technology (SCAT) 172 Sasol East 199 Sasol Slurry Bed Process (SSBP) 173 Sasol Synfuels 261, 262 – evolution of 199–212 – – coal pyrolysis product refining, changes in 211–212 – – condensate and oil workup sections 206, 209 – – Fischer–Tropsch aqueous product refining, changes in 210–211 – – Fischer–Tropsch condensate refining, changes in 202–203 – – Fischer–Tropsch oil refining, changes in 205–210 – – Fischer–Tropsch synthesis, changes in 201–202 – – linear 1-alkenes, extraction of 204–205 – – syngas production, changes in 201 – – synthetic jet fuel 212 – reactors 183 Sasol West 199 Schulz–Flory equation 78 sec-alcohols 77 second generation crude oil refineries 33–35, 34, 34, 36 Second World War – high octane aviation gasoline, demand for 35 secondary pyrolysis 59 Secunda 181 semiregenerative units 448 semisynthetic jet fuel 279 sensitivity, of octane number 255 Shell Gas BV 231 Shell gasification process (SGP) 232–233 Shell MDS (Malaysia) Snd Bhd company 231

Shell Middle Distillate Synthesis (SMDS) process 11, 231, 241 – Fischer–Tropsch refining, in Bintulu GTL – – aqueous product treatment 238 – – oil refining 235–238 – Fischer–Tropsch synthesis, in Bintulu GTL 233–235 – Pearl GTL facility 238 – refinery design 239 – syngas production in Bintulu GTL 232–233 Shell Research and Technology Centre 231 Shell’s Pearl GTL facility 17 short path distillation (SPD) 177, 238 single-carbon-number hydroisomerization 365 skeletal isomerization 314–315, 353–354, 357–358 – butene isomerization catalysis 358–359 – hydroisomerization 319–320 – pentene isomerization catalysis 359–360 – syncrude process technology 360 slack wax 132, 135–136, 177 slagging moving bed gasification 61–62 slurry bed reactors 85, 142, 173, 173 – composition 174 – compound classes 174 slurry-feed entrained flow gasification 65–66 slurry-phase distillate (SPD) process, Sasol 243 smoke point 276 solid carbon sources 52–53 – composition 53 – syngas production from 58–66 – – gasification technologies, comparison 66 – – heteroatoms, gasification of 59–60 – – high-temperature entrained flow gasification 64–66 – – low-temperature moving bed gasification 60–62 – – medium-temperature fluidized bed gasification 62–63 solid phosphoric acid (SPA) catalyst 190 – in alkene oligomerization 375–378 – key aspects of 376–377 ‘‘sour’’ crude 23 South African Coal, Oil and Gas Corporation 153 sp2 - and sp3 -hybridized carbon coupling, for chain growth 75–76 spark-ignition engine 251, 253, 264 spindle oil 134 stabilized light oil (SLO) 114, 222 stabilized oil 147 stand-alone Fischer–Tropsch-based petrochemical facility 594, 596, 600 stand-alone refining 11 Standolind Oil and Gas Company 141 steam reforming 6, 53, 56, 58 – advantages of 56

Index stereochemical isomerization 353 stoichiometric ratio 87 storage stability 261, 278 Stretford process 182 substitute natural gas (SNG) 545 sulfides, in crude oil 24 Sulfolin process 182 sulfur 7 – -based chemicals 11 – gasification of 59–60 – compounds – – in catalyst deactivation 89, 89 – – in crude oil 23–24, 24, 24 sulfur dioxide (SO2), in catalyst deactivation 89 surface active compounds 112 ‘‘sweet’’ crude 23 syncrude – chemicals refining concepts for – – alkane-based refining 585–586 – – alkene and oxygenate recovery 587, 587 – – aromatics production 586, 587 – – fuels and chemicals coproduction 588–591 – cooling and separation 109–115 – – cyrogenic separation 110–111, 111 – – design 106 – – HTFT syncrude recovery 113–114 – – LTFT syncrude recovery 114–115 – – oxygenate partitioning 111–113, 111 – – pressure separation 110 – vs. crude oil, comparison 12–13, 13 – process technology 484–485 – recovery 138 syncrude-to-product conversion 10–13 – fuels versus chemicals 11–12 – upgrading and refining 10–11 syngas – cleaning 7–8, 8, 51, 66–69, 67, 120 – – acid gas removal 67–69 – – Sasol 2 and 3 facility 182–183 – conditioning 7–8, 8, 51, 69–70, 105 – – water gas shift (WGS) conversion 52–53, 54, 69–70 – unconverted 105–106 syngas production 5–7, 51, 201 – American Hydrocol facility 142–143 – in Bintulu GTL 232–233 – gas reforming 218–220 – German Fischer–Tropsch facilities 119–121, 121 – from natural gas 53–58, 54 – – adiabatic oxidative reforming 56–57 – – adiabatic prereforming 55–56 – – gas cleaning 54, 55 – – gas reforming technologies, comparison 57, 58 – – steam reforming 56

– – – – – – – – – – – – –

natural gas liquid recovery 218 Oryx 242–243 raw materials 51–53 Sasol 1 facility 154–156, 172 – Lurgi dry ash coal gasification 154–155, 155 – rectisol syngas cleaning 155–156 Sasol 2 and 3 facilities 182–183, 183 – Lurgi dry ash coal gasification 182 – syngas cleaning 182–183 from solid carbon sources 58–66 – gasification technologies, comparison 66 – heteroatoms, gasification of 59–60 – high-temperature entrained flow gasification 64–66 – – low-temperature moving bed gasification 60–62 – – medium-temperature fluidized bed gasification 62–63 syngas-to-syncrude conversion 8–10 synthesis gas. see syngas synthetic fuel, properties 170–171, 198, 199, 227 synthetic jet fuel 212, 271–272, 274 Synthetic Liquids Fuels Act 141 synthetic lubricants 585 synthetic natural gas (SNG) 52 synthol HTFT condensate refining 188–192, 189 – naphtha and distillate fractions, fuel properties 191 synthol HTFT oil refining 192–194 synthol reactors 157 syntroleum S-5 synthetic jet fuel 542

t tail gas 107, 114, 115, 144, 186 – processing 222 – recycle systems 108, 108 tail pipe catalytic converter 39 tar 67 Tar Naphtha Phenol Extraction (TPNE) 177 technology selection – for diesel fuel refining 566–567, 566 – for jet fuel refining 546–547, 546 – and motor-gasoline refining 519–521 tetraethyl lead (TEL) 35, 39, 198, 252, 256, 263, 264 thermal cracking 134, 134, 166, 324–325, 407, 410–414, 411, 419, 546, 565 – syncrude processing technology 421 thermal efficiency 14–15 thermal naphtha reforming 443–444 thermal oligomerization, in alkene oligomerization 384–385 thermal reforming 210 thermal stability 278 thiols, in crude oil 24 thiophenes, in crude oil 24 thiophenol 401

619

620

Index third generation crude oil refineries 36–39, 38 total acid number (TAN) 23 T-point terminology 260 Tropsch, Hans 73 true-vapor-phase (T-V-P) process 131–132 turbine engines, in aviation 35

u United States, Fischer–Tropsch facility in. see American Hydrocol facility Universal Oil Products (UOP) 131 – Catalytic Polymerization process 164, 189 – Penex technology 225 – Platforming technology 192 unstabilized light oil (ULO) 114 upgrading 11 US Bureau of Mines 141

v vacuum distillation 36, 38, 44 valve seat recession (VSR) 263 vanadium 183 – in crude oil 26 vapor pressure – of crude oil 27 – of fuel 260 Viktor-plant 129 visbreaking 324

viscosity index (VI) 134, 584, 598, 599 viscosity of crude oil 28

w Waksol A 176 Waksol B 176 waste-to-liquids (WTLs) process 3 water, alkene hydration 346 water gas shift (WGS) catalyst 120 water gas shift (WGS) reaction 52–53, 54, 69–70 water-soluble oxygenates 136, 149 – composition of 149 wax(es) 115, 585, 588 – hydrogenation 166 – hydroisomerization 360 – refining 135–136 – properties 136 wax hydroisomerization catalysis 364 wax hydrotreating and wax hydrocracking 553 waxy oil 194 waxy raffinate 236 World Wide Fuel Charter (WWFC) guidelines 252, 254, 285

z zeolite catalysts 341 zeolites, in coprocessing zinc oxide (ZnO) 55

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