Zeolites As Catalysts, Sorbents, and Detergent Builders: Applications and Innovations : Proceedings (Studies in Surface Science and Catalysis)

Studies in Surface Science and Catalysis 46 ZEOLITES AS CATALYSTS, SORBENTS AND DETERGENT BUILDERS Applications and In...

Author: H. G. Karge | J. Weitkamp | Editors

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Studies in Surface Science and Catalysis 46

ZEOLITES AS CATALYSTS, SORBENTS AND DETERGENT BUILDERS Applications and Innovations

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Studies in Surface Science and Catalysis Advisory Editors:B. Delmon and J.T. Yates

Vol. 46

ZEOLITES AS CATALYSTS. SORBENTS AND DETERGENT BUILDERS Applications and Innovations Proceedings of an International Symposium, Wurzburg, F.R.G., September 4-8,1988

Editors

H.G. Karge Fritz-Haber-lnstitut der Max-Planck-Gesellscha ft, Faradayweg 4-6, D- 1000 Berlin 33 (West)

J. Weitkamp University of Stuttgart, Institute of Chemical Technology I, Pfaffenwaldring, D- 7000 Stuttgart 80, F. R. G.

ELSEVIER

Amsterdam - Oxford - New York -Tokyo

1989

ELSEVIER SCIENCE PUBLISHERS B.V. Sara Burgerhartstraat 25 P.O. Box 21 1, 1000 AE Amsterdam, The Netherlands Distributors for the United States and Canada: ELSEVIER SCIENCE PUBLISHING COMPANY INC. 655, Avenue of the Americas New York, NY 10010, U S A . L l b r i r y of Congress C 8 t 8 I o g l n g - l n - P u b l l c a t I n n

Zeolites a s c a t a l y s t s . s o r b e n t s . and d e r e r g e n r b u l l d e r r

Data

applications

and i n n o v a t i o n s P r O c e e d l n g s o f an i n t e r n a t t o n a l s y n p o s i u n . WuPZbuPg. F . R . G . . Smptemb8r 4-8. 1988 / 0 d l T O r S . H.G. K a r g n . J. He I r k a m p . p. cm. ( S t u d l e i I n r u r f a c n s c l e n c o and c a t i l y s l s , 4 6 ) P r o c a e d l n p s o f t h e I n r 8 r n a r l o n a l Symposium on "Zeolltss a s C a r a l y s t s . S o r b e n t r . and D s t n r g 8 n t B u l l d a r s . " I n c l u d e s indexes. Blbliography p. ISBN 0-444-87383-x 1. ZeoIites--Congrcsrsr. 2 . Sorbents--Congresres. 3 . D8Tmrponts. Synthetlc--Conprssses. I . Kargm. H. 0 . t n e l l m u r 0 . ) 11. W8ltkamp. J. ( J e n s ) 111. I n r s r n a t l o n a l Symposium on "Zeolltss as C a t i l y s t s . S o r b a n t s . ana D e t e r g e n t B u l l d 8 r S ' (1988 H u r z b u r g . Germany) i V . Sa-les. ~ ~ 2 4 5 . ~ 5 198s z m 660 . 2 9 9 5 - - d c 2 0 89- 1464 CIP

--

ISBN 0-444-87383-X (VOI.46) ISBN 0-444-4 1801-6 (Series)

0 Elsevier Science Publishers B.V., 1989 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publisher, Elsevier Science Publishers B.V./ Physical Sciences & Engineering Division, P.O. Box 330, 1000 AH Amsterdam, The Netherlands.

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Special regulationsfor readers in the USA This publication has been registered with the Copyright Clearance Center Inc. (CCC), Salem, Massachusetts. Information can be obtained from the CCC about conditions under which photocopies of parts of this publication may be made in the USA. All other copyright questions, including photocopying outside of the USA, should be referred t o the publisher. No responsibility is assumed by the Publisher for any injury and/or damage to persons or property as a matter of products liability, negligenceor otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein. Although all advertising material is expected to conform to ethical (medical)standards, inclusion in this publication does not constitute a guarantee or endorsement of the quality or value of such product or of the claims made of it by its manufacturer. Printed in The Netherlands

V

CONTENTS

.......................... XI11 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . XIV International Scientific Committee . . . . . . . . . . . . . . . . . . .X I V Executive Committee ........................... XV Preface

Financial Support

...........................

xv

I . CATALYSIS AND CATALYSIS-RELATED PROPERTIES

Skeletal Rearrangement Reactions of Olefins, Paraffins and Aromatics over Aluminophosphate based Molecular Sieve Catalysts J.A. Rabo, R.J. Pellet, P.K. Coughlin, E.S. Shamshoum

.........1

Catalytic and Physical Properties of Silicon-Substituted AlP04-5 Molecular Sieves K.J. Chao, L.J. Leu

...........................

On the Nature of the Catalytic Activity of SAPO-5 Ch. Minchev, V. Kanazirev, V. Mavrodinova. V. Penchev, H. Lechert

19

. . . . 29

Molecular Orbital Calculations on the Structural and Acidic Characteristics of Aluminophosphates (AlPO). Si 1 icoaluminophosphates (SAPO) and Metaluminophosphate (MeAPO) Based Molecular Sieves R. Carson, E.M. Cooke, J. Dwyer, A. Hinchliffe, P.J. O'Malley

. . . . . . 39

Relation between Paraffin Isomerisation Capability and Pore Architecture of Large-Pore Bifunctional Zeolites J.A. Martens, M. Tielen, P.A. Jacobs.

..................

49

Respective Influences of the Geometric and Chemical Factors in the Conversion o f Aromatics over Acidic Zeolites F. Fajula, M. Lambret, F. Figueras

. . . . . . . . . . . . . . . . . . . 61

Para-Selectivity of Pentasil Zeolites 3.-H. Kim. S. Namba, T. Yashima

.....................

71

v1

Hydrogen Spillover in the Conversion of n-Alkanes on Zeolites K.-H. Steinberg, U. Mroczek, F. Roeher

. . . . . . . . . . . . . . . . 81

Intermediates in the Formation of Aromatics from Propene and 2-Propanol on H-ZSM-5 Zeol i tes H. Lechert, C. Bezouhanova, C. Oimitrov, V. Nenova

. . . . . . . . . . . 91

Zeolite and Matrix Structures and their Role in Catalytic Cracking C.J. Groenenboom

...........................

99

Evaluation of Non-Commercial Modified Large Pore Zeolites in FCC E. Jacquinot, F. Raatz, A. Macedo. Ch. Marcilly

. . . . . . . . . . . . 115

Surface-Metals Interactions in Fluid Cracking Catalysts During the Upgrading of Vanadium Contaminated Gas Oils M.L. Occelli, J.M. Stencel

.......................

127

Highly Dispersed Pt and Pt-Cr Clusters in Pentasils and their Activity in Transformations of Lower Alkanes E.S. Shpiro, G.J. Tuleuova, V.I. Zaikovskii, O.P. Tkachenko, T.V. Vasina, O.V. Bragin, Kh.M. Minachev

. . . . . . . . . . . . . . . . 143

Conversion of Light Alkanes into Aromatic Hydrocarbons. 3. Arornatization of Propane and Propene on Mixtures of HZSM5 and of Ga2O3 N.S. Gnep, J.Y. Doyemet, M. Guisnet

. . . . . . . . . . . . . . . . . . 153

Shape-Selective Catalysis in Zeolites with Organic Substrates Containing Oxygen R.F. Parton, J.M. Jacobs, O.R. Huybrechts and P.A. Jacobs.

. . . . . . . 163

lhe Use of Zeolite Catalysts for the Synthesis of Nitrogen-Containing Organic Intermediates W.F. Hoelderich

............................

193

Comparison of the Alkylation of Anisole and Phenol wifh Methanol on Pentasil and Ultrastable Zeolites R.F. Parton. J.M. Jacobs. H.v. Ooteghem, P.A. Jacobs

. . . . . . . . . . 211

Acidity Effect o f ZSM 5 Zeolites on Phenol Methylation Reaction N.S. Chang, C.C. Chen, S.J. Chu, P.Y. Chen, T.K. Chuang

. . . . . . . . 223

VII

A new Catalyst for MIBK Synthesis - Palladium on ZSM-5 Zeolites P.Y. Chen, S.J. Chu, N.S. Chang, T.K. Chuang, L.Y. Chen.

. . . . . . . . 231

Acetylene Hydration on Zeolite Catalysts: An I.R. of the Surface Species Gy. Onyestyak, J. Papp Jr.. 0. Kallo

Spectroscopic Study

. . . . . . . . . . . . . . . . .241

Preparation and Characterization of Mo-HY Zeolites A. Meszaros-Kis, J. Valyon

251

Propylene Metathesis Reaction over Mo/Y-Zeolites M. Caniecki

259

......................

..............................

Molybdenum-Oxide-Modif ied Pentasil Zeolites I.M. Harris, J. Dwyer, A.A. Garforth, C.H. McAteer, W.J. Ball

. . . . . 271

Surface and Catalytic Properties of the New Zeolite Type LZ 132 Z. TvaruZkova, M. Tupa, P. Jiru. A. Nastro. 6. Giordano, F. Trifiro

. . 281

PtRh-Doped Zeolites as Three-Way-Catalysts: SIMS Analysis as a Tool for the Selection of Suitable Zeolite Types C. Plog, J. Haas, J. Steinwandel

. . . . . . . . . . . . . . . . . . . 295

Transformation o f Ethanethiol over Zeolites M. Ziol’ek, P. Decyk, M. Derewinski, J. Haber

. . . . . . . . . . . . . 305

Study o f the Structure and the Redox Reactivity of NaX Encapsulated Co( 1 I)-Phthalocyanine G. Schulz-Ekloff, 0. Wohrle, V. Iliev, E. Ignatzek, A. Andreev Selective Reduction o f Nitric Oxide over Zeolite-Supported Iridium Catalyst R. Myrdal, St. Kolboe

. . . . 315

........................

Metal-Doped Zeolites for Selective Catalytic Reduction of Nitrogen Oxides in Combustion Gases J.Haas, J.Steinwande1, C. Plog

327

. . . . . . . . . . . . . . . . . . . 337

Vlll

Preparation of NiHZSM-5 Catalyst for Isomerization o f c8 Aromatics. Solid-state Incorporation of Nickel B. Wichterlova. S. Beran, L. Kubelkova, J. Novakova, A. SmieSkova, R. Sebik

347

Formation of Carbocations from c6 Compounds in Zeolites I. Kiricsi, H. Forster, G. Tasi

355

............................... ....................

An Infrared and Catalytic Study o f Isomorphous Substitution in Pentasil Zeolites M.F.M. Post, T. Huizinga, C.A. Emeis, J.M. Nanne, W.H.J. Stork

. . . . 365

Calorimetric lnvestigation o f the Acidity of Dealuminated Y-Type Zeolites Using Various Basic Probes A. Auroux. Z.C. Shi, N. Echoufi, Y . Ben Taarit

. . . . . . . . . . . . 377

The Acidity of a Modified Faujasite Structure, Zeolite CSZ-1 S. Cartlidge. R.L. Cotterman, M.L. Howes

. . . . . . . . . . . . . . . 389

Control of Catalytic Properties of ZSM-5 made by Fast and Template-free Synthesis A. TiAler, P. Polanek, U. Girrbach, U. Muller, K.K. Unger Theoretical Studies of BrBnsted Acidity in Zeolites R. Vetrivel. C.R.A. Catlow. E.A. Colbourn. M. Leslie

. . . . . . . 399

. . . . . . . . . 409

N M R and I R Studies of Zeolites of the Erionite Type F. Roefiner, K.-H. Steinberg, 0. Freude, M. Hunger, H. Pfeifer

. . . . 421

Specific Platinum Particles Properties in Basic Zeolites A. de Mallmann, D. Barthomeuf

....................

11.

429

SORPTION

Fundamental Research and Modeling for a Technical Process of Selective Adsorption of Normal Paraffins ("Parex"-Process of DDR) by Zeolite A W. Schirmer, K. Fiedler, H. Stach, M.Suckow

. . . . . . . . . . . . . 439

Sorbex Technology for Industrial Scale Separation J.A. Johnson, A.R. Oroskar

......................

451

IX

Gas Oil Dearomatization by Adsorption A. Laktic, J. Muhl. I. Beck. M. Beer

. . . . . . . . . . . . . . . . . 469

Modeling Diffusion Pathways in MFI Materials by Time-Resolved Powder Diffraction Techniques B.F. Mentzen

.............................

477

Measurement of Intracrystalline Diffusivities of HZSM-5 Zeolite at Higher Temperatures and Predictions of Shape Selectivity K. Hashimoto, T. Masuda, M. Kawase

. . . . . . . . . . . . . . . . . . 485

Measurement of Hydrocarbon Diffusion Coefficient in a Non-Isobaric Chromatographic Column of Zeolite Crystal Powder E. Aust, W. Hilgert, G. Emig

.....................

495

Molecular Mobility of Benzene and p-Xylene in M F I Type Zeolites M. Bulow, J. Caro, B. Rohl-Kuhn, B. Zibrowlus

. . . . . . . . . . . . 505

Diffusion of n-Hexane and 3-Methylpentane in H-ZSM-5 Crystals of Various Sizes P. Voogd, H. van Bekkum

........................

519

Comparative Study by Deuteron Solid State NMR Spectroscopy of the Dynamics o f Benzene and Olefins in Faujasite- and Mordenite-Type Zeolites B. Boddenberg. R. Burmeister, G. Spaeth

k

. . . . . . . . . . . . . . . 533

Probing the Hydrogen Sorption States in Zeolites A by Infrared Spectroscopy and Low-Temperature Gas Chromatography Supplemented by Theoretical Calculations H. Forster, W. Frede, G. Peters

. . . . . . . . . . . . . . . . . . . 545

Fourier-Transform Infra-Red Photoacoustic Spectroscopy, A Useful Technique for the Study of Strongly Physisorbed Molecules J. Philippaerts, E.F. Vansant, Y.A. Yan

. . . . . . . . . . . . . . . 555

Adsorption Properties of Large Crystals of ZSM-5 Zeolite as a Function of the Degree of Dealumination J. Kornatowski, M. Rozwadowski, A. Gutsze, K.E. Wisniewski

. . . . . . 567

X

Self-Consistent-Charge Xu Calculations of Sorption Complexes of Nitrous Oxide Attached to Transition Metal Occupied Zeolite Clusters 0. Zakharieva-Pencheva, M. Grodzicki, H. Forster

. . . . . . . . . . . 575

IR Study o f the Adsorption of Benzene on HZSM5 A. Jentys, J.A. Lercher

......................

565

Adsorption Separation o f Methylnaphthalene Isomers on X and Y Zeolites V. Solinas. R. Monaci, E. Rombi, M.Morbidelli

. . . . . . . . . . . . 595

Oxygen Enrichment of Air with Molecular Sieve Zeolites Using the PSA/VSA Technique G. ReiR

..............................

607

Adsorption and Diffusion o f Different Hydrocarbons in MFI Zeolite of Varying Crystallite Size D.H. Lin, V. Ducarme, 6. Coudurier, J.C. Vedrine

. . . . . . . . . . . 615

High Resolution Sorption Studies of Argon and Nitrogen on Large Crystals of Aluminophosphate A1 Po4-5 and Zeolite ZSM-5 U. Muller, K.K. Unger, 0. Pan, A. Mersmann, Y. Grillet, F. Rouquerol. J. Rouquerol

......................

625

A new Potential Large-Scale Application o f Zeolites as Fire-Retardant Material H.K. Beyer, G. Borbely, P. Miasnikov, P. Rozsa

. . . . . . . . . . . . 635

111. ION EXCHANGE AND DETERGENT BUILDING

Industrial Production of Zeolites E. Roland

645

Calcium and Magnesium Exchange in Na-A, Ma-X and their Precursor Gels L.V.C. Rees

661

.............................

.............................

Fundamentals of Phosphate Substitution in Detergents by Zeolites Cobuilders and Optical Brighteners M.J. Schwuger, M. Liphard

-

.....................

673

XI

Zeolite A - A Builder for Liquid Detergents? W. Leonhardt, B.-M. Sax

691

Development and Performance of Zeol ite-A-Bui It Non-Phosphate Detergents H. Upadek, P. Krings

701

.......................

........................

Simultaneous Separation of Suspended Sol ids, Ammonium and Phosphate Ions from Waste Water by Modified Clinoptilolite J. Olah. J. Papp, A. Meszaros-Kis, Gy. Mucsi, 0. Kallo

. . . . . . . . 711

IV. MODIFICATION AND CHARACTERIZATION Framework and Non-Framework A1 Species in Dealuminated Zeolite Y P.J. Grobet, H. Geerts, M. Tielen, J.A. Martens and P.A. Jacobs Characterization of Calcined FAPO-5 S. Schubert, H.M. Ziethen, A.X. Trautwein, F. Schmidt, H.-X. J.A. Martens, P.A. Jacobs

. . . 721

Li,

......................

Control of Pore-Opening Size of Zeolites Y.F. Chu, C.F. Keweshan, E.F. Vansant

735

. . . . . . . . . . . . . . . . . 749

Structural-Modification Technique for Zeolites: Chemisorption o f Si2H6 Y. Yan, J . Verbiest, J. Philippaerts, E.F. Vansant. P. De Hulsters I\ new

. . . 759

Dealumination of the Zeolites Offretite and Erionite Studied by Sol id-State 29Si- and 27A1-MAS NMR Spectroscopy K.P. Lillerud, M.Stocker

769

Gal liation and 180-exchange Reactivities of ZSM-5 and ZSM-11 A. Endoh, K. Nishimiya, K. Tsutsumi, T. Takaishi

779

Thermal Decomposition of Ironpentacarbonyl in Zeolites of Faujasite Type. A Study of the Influence of Argon, HE, H2/CO Gas Mixture and Various Si/Al Ratios Using Mossbauer, ESR and Mass Spectroscopy H.M. Ziethen. A.X. Trautwein

709

....................... ...........

....................

Investigation of Ultra Stable Y by Differential Thermal Analysis after Injection of Water Vapour A. Yoshida, K. Inoue

. . . . . . . . . . . . . . . . . . . . . . . . . 801

Properties of Hydrothermal Low-Damaged 5A and 1OX Zeolites R. Schollner, H. Siege1

. . . . . . . . . . . . . . . . . . . . . . . . 811

Phase Transformations and Changes in Lattice Parameters of ZSM-5 as a Function of A1 Content and Temperature G.T. Kokotailo, L. Riekert, A. TiRler

. . . . . . . . . . . . . . . . . 821

The Effect of Sorbates and Elevated Temperatures on the Structures of Some Zeolite Catalysts C.A. Fyfe, G.T. Kokotailo, H. Strobl, H. Gies, G.J. Kennedy, C.T. Pasztor, G.E. Barlow

. . . . . . . . . . . . . . . . . . . . . . 827

The Effect of Temperature and Sorption of p-Xylene and Benzene on the Structure of ZSM-5 G.T. Kokotailo, L. Riekert, A. TiSler.

. . . . . . . . . . . . . . . . . 843

The Characterization of Modified ZSM-5 Catalysts prepared via a Sol id-state Reaction for Propane Aromatization Y. Yang, X. Guo, M. Oeng, L. Wang, Z. Fu

. . . . . . . . . . . . . . . . 849

Author Index

......,.....,.. ............ ....

Subject Index

. . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . 863

Studies in Surface Science and Catalysis (other volumes in the series). .

859

. 869

XI11

PREFACE

This symposium was one of the smaller zeolite meetings held in between the big International Zeolite Conferences. It is the latest in the series of meetings which started in 1978 in Szeged, Hungary, and continued in 1980 in Villeurbanne (Lyon), France; 1982 in Bremen, FRG; 1984 in Prague, Czechoslovakia; 1985 in Si6fok, Hungary; and 1987 in Nieuwpoort, Belgium. These conferences are intended t o cover selected fields from the broad area of zeolite research and application. For the Wurzburg Symposium emphasis was placed on zeolite catalysis, sorption and detergent builders. With respect t o catalysis, particular attention was paid to the synthesis of fine chemicals with the help of zeolite catalysts. An overview of this important field was given in two invited lectures which were complemented by a number of related oral and poster contributions. Special efforts were made to bring together experts from industry and academia. This endeavour was successful, as was reflected both in the invited lectures, oral and poster presentations and in the composition of the audience. An expected trend was the ever increasing interest in the so-called new generation molecular sieves both for research and application. A remarkable number of the presented studies were devoted t o these materials. Innovations, however, were mostly visible in developing and refining methods and techniques of investigation either in experiment or theory. Obviously, successful application of highly sophisticated tools of solid state and surface science t o problems of zeolite research now becomes possible. This seems t o promise a growth in our knowledge of and deeper insight into the subtle details of zeolite properties and behaviour.

Hellmut G. Karge Fritz Haber institute Max Planck Society, Berlin

January, 1989

Jens Weitkamp institute of Chemical Technology I University of Stuttgart

XIV

ACKNOWLEDGMENTS The organizers of the international Symposium on "ZEOLITES AS CATALYSTS, SORBENTS AND DETERGENT BUILDERS", held at Wurzburg, Federal Republic of Germany, September 4-8, 1988 express their appreciation to the members of the International Scientific Committee who carried out the difficult and important task of paper selection. They also wish t o thank the members of the Executive Staff for their great efforts made during preparation and running of the symposium. Particular thanks are due to Mrs. R. Stottko for the coordination and execution of the finances, to Dr. St. Ernst for his active participation in the organizational work and to Mrs. M. Rahimi, Mrs. E. Stankewitz and Mrs. J. Reiffel for their most valuable assistance in preparing the proceedings. Furthermore, the organizers thank the authors for submitting their manuscripts for publication in these proceedingsand the referees for spending time and effort in order to ensure the high scientific standard of the contributions. Last but not least, the help and generous financial support of collaborating organizations and sponsors from the industry is gratefully acknowledged.

Hellmut G. Karge

Jens Weitkamp.

INTERNATIONAL SCIENTIFIC COMMlllEE H. BEYER, HungarianAcademy of Sciences, Budapest, Hungary. 5. CARTLIDGE, Grace GmbH, Worms, FRG. P. CHRISTOPHLIEMK, Henkel KGaA, Dusseldorf, FRG. J. DWYER, The University of Manchester, England.

F. FAJULA, Ecole Nationale Supkrieure de Chimie, Montpellier, France. F. FETTING, Technische Hochschule Darmstadt, FRG.

W. H6LDERICH. BASF AG, Ludwigshafen, FRG. W. KEIM, RWTH Aachen, FRG, and DMGK, Hamburg, FRG. A. KISS, Degussa AG, Hanau, FRG.

H. KRAL, Dechema, FrankfurVM., FRG.

xv E.4. LEUPOLD, Hoechst AG, FrankfuWM., FRG. R. MAUREL, lnstitut de Recherches sur la Catalyse, Villeurbanne, France. I.E. MAXWELL, Koninklijke/Shell, Amsterdam, The Netherlands. L. MOSCOU, Akzo Chemie BV, Amsterdam, The Netherlands. G. OHLMANN, Academy of Sciences of the GDR, Berlin-Adlershof, GDR. L. PUPPE, Bayer AG, Leverkusen, FRG.

M.S. SPENCER, ICI, Billingham, England. J.B. UYlTERHOEVEN, Katholieke Universiteit Leuven, Belgium.

EXECUTIVE COMMllTEE R. AMBERG, Berlin (West).

C.H.BERKE, Stuttgart, FRG. A. BREHM, Oldenburg, FRG. C.-Y. CHEN, Oldenburg, FRG.

H. DARMSTADT, Berlin (West). St. ERNST, Oldenburg, FRG.

TH. KROMMINGA, Stuttgart, FRG. D. LINDNER, Oldenburg, FRG. G.W. MULLER, Stuttgart, FRG. M. NEUBER, Karlsruhe, FRG. W. NIESSEN, Berlin (West). E. PERNKLAU, Stuttgart, FRG. E. STANKEWITZ, Berlin (West). R. STOTTKO, Berlin (West).

W. WACHSMANN, Berlin (West).

FINANCIAL SUPPORT Akzo Chemie, Ketjen Catalysts, Amsterdam, The Netherlands. BASF AG, Ludwigshafen, FRG. BP International Limited, Sunbury-on-Thames, England.

Bayer AG, Leverkusen, FRG.

XVI

Degussa AG, Frankfurt, FRG. Deutsche Forschungsgemeinschaft(DFG), Bonn, FRG. Deutscher Akademischer Austauschdienst (DAAD), Bonn, FRG. DGMK German Society for Petroleum Sciences and Coal Chemistry, Processing and Application Division, Hamburg, FRG. Exxon Chemical Holland B.V., Rotterdam, The Netherlands. Grace GmbH, Worms, FRG. Henkel KGaA, Dussseldorf, FRG. Hoechst AG, Frankfurt, FRG. lnstitut Frangais du Petrole, Rueil Malmaison, France. International Zeolite Association (IZA). Kali-Chemie AG, Hannover, FRG.

Max-Planck-Gesellschaft, Munchen, FRG. Perkin Elmer GmbH, Uberlingen, FRG. Rutgerswerke AG, Frankfurt, FRG. SKW Trostberg AG, Trostberg, FRG.

Sud-Chemie AC, Miinchen, FRG.

I. CATALYSIS AND CATALYSIS-RELATED PROPERTIES


H.G. Karge, J . Weitkamp (Editors), Zeolites as Catalysts, Sorbents and Detergent Builders 1989 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands

SKELETAL REARRANGEMENT REACTIONS OF OLEFINS,

PARAFFINS AND AROMATICS OVER

ALUMINOPHOSPHATE BASED MOLECULAR S I E V E CATALYSTS

J u l e A. Rabo, Regis J . P e l l e t , P e t e r K. C o u g h l i n and Edwar S. Shamshoum Union Carbide C o r p o r a t i o n , O l d Saw M i l l R i v e r Road, Tarrytown, NY 10591, U.S.A.

ABSTRACT Medium pore aluminophosphate based m o l e c u l a r s i e v e s w i t h t h e -11, -31 and -41 c r y s t a l s t r u c t u r e s a r e a c t i v e and s e l e c t i v e c a t a l y s t s f o r 1-hexene i s o m e r i z a t i o n , hexane d e h y d r o c y c l i z a t i o n and c 8 a r o m a t i c r e a c t i o n s . With o l e f i n feeds, t h e y promote i s o m e r i z a t i o n w i t h l i t t l e loss t o competing hydride transfer and c r a c k i n g r e a c t i o n s . With C8 aromatics, they e f f e c t i v e l y c a t a l y z e xylene i s o m e r i z a t i o n and ethylbenzene d i s p r o p o r t i o n a t i o n a t v e r y low xylene loss. As a c i d components i n b i f u n c t i o n a l c a t a l y s t s , t h e y a r e s e l e c t i v e f o r p a r a f f i n and c y c l o p a r a f f i n i s o m e r i z a t i o n w i t h low c r a c k i n g activity. I n these r e a c t i o n s t h e medium p o r e aluminophosphate based s i e v e s a r e g e n e r a l l y l e s s a c t i v e b u t s i g n i f i c a n t l y more s e l e c t i v e t h a n t h e medium pore z e o l i t e s . S i m i l a r i t y w i t h medium p o r e z e o l i t e s i s d i s p l a y e d b y an o u t s t a n d i n g r e s i s t a n c e t o coke induced d e a c t i v a t i o n and b y a v a r i e t y o f shape s e l e c t i v e actions i n catalysis. The e x c e l l e n t s e l e c t i v i t i e s observed w i t h medium pore aluminophosphate based s i e v e s i s a t t r i b u t e d t o a unique combinat i o n o f m i l d a c i d i t y and shape s e l e c t i v i t y . S e l e c t i v i t y i s a l s o enhanced by t h e presence o f t r a n s i t i o n metal framework c o n s t i t u e n t s such as c o b a l t and manganese which may e x e r t a chemical i n f l u e n c e on r e a c t i o n i n t e r m e d i a t e s . INTRODUCTION According t o recent reports,

t h e aluminophosphate based m o l e c u l a r s i e v e s

have a c i d i c c a t a l y t i c a c t i v i t y f o r a broad a r r a y o f p e t r o l e u m r e f i n i n g and petrochemical

reactions.

activities

were

molecular

sieves.

reported

In

early

for

a

SAPO

These

studies

number

of

molecular

Subsequently,

substitution

aluminophosphate

certain

2)

n-butane

cracking

(SAPO)

sieves

showed

weak

acidity

by

i t was found t h a t t r a n s i t i o n m e t a l

comparison w i t h z e o l i t e s . into

(ref.

silicoaluminophosphate

crystals

resulted

i n enhanced

a c i d i t y as i n d i c a t e d b y enhanced butane c r a c k i n g a c t i v i t y ( r e f .

3).

With

medium pore species t h e g e n e r a l l y m i l d a c i d i t y combined w i t h u n i q u e shape selectivity reactions.

has Thus,

resulted

in

a r e v i e w of

improved

phosphate based m o l e c u l a r s i e v e s catalytic

cracking

reforming

(ref.

conversion

(refs.

(ref.

7),

4),

aromatic

9,lO)

and

catalytic

selectivity

in

several

t h e p a t e n t l i t e r a t u r e r e v e a l s t h a t aluminohave

shown c a t a l y t i c

hydrocracking alkylations

(ref. (ref.

activity

in fluid

5), dewaxing ( r e f . 6), 8 ) , methanol t o o l e f i n

i n o l e f i n oligomerization

(refs.

8.11).

In

s e v e r a l cases o l e f i n s p l a y an i m p o r t a n t r o l e , e i t h e r as f e e d c o n s t i t u e n t s o r

as r e a c t i o n i n t e r m e d i a t e s .

The enhanced s e l e c t i v i t y o f c e r t a i n SAPO's f o r

o l e f i n r e a c t i o n s has a l r e a d y been noted. SAPO-34,

s m a l l p o r e SAPO's,

such as

were found v e r y e f f e c t i v e a t i n t e r c o n v e r t i n g l i g h t o l e f i n s such as

ethylene,

propylene

and

butylenes

12).

oligomeric products ( r e f , very

Thus,

selective

for

with

little

loss

to

paraffinic

or

The medium p o r e SAPO's were a l s o a c t i v e and

oligomerization

of

p r o p y l e n e and butenes t o o l e f i n i c

11) o r t o d i s t i l l a t e s w i t h o u t the production o f p a r a f f i n s o r

gasoline ( r e f . aromatics. The

present

aluminophosphate

paper

on

reports

molecular

the

sieves

in

catalytic model

properties

hydrocarbon

of

selected

reactions.

The

m o l e c u l a r s i e v e s were s e l e c t e d t o r e p r e s e n t l a r g e and medium p o r e s i z e s w i t h

a v a r i e t y o f framework elements i n c l u d i n g t r a n s i t i o n m e t a l s , i n a d d i t i o n t o aluminum and phosphorus.

Model

r e a c t i o n s were chosen t o e x p l o r e c a t a l y t i c

performance i n p a r a f f i n , o l e f i n and a r o m a t i c rearrangement r e a c t i o n s t o probe molecular

sieve

character,

shape

selectivity

and

catalytic

activity,

p a r t i c u l a r l y for reactions i n v o l v i n g o l e f i n s or o l e f i n r e a c t i o n intermediates. EXPERIMENTAL M o l e c u l a r Sieve C a t a l y s t P r e p a r a t i o n The aluminophosphate based m o l e c u l a r s i e v e s used i n t h e p r e s e n t s t u d y were prepared a c c o r d i n g t o procedures d e s c r i b e d i n US P a t e n t ( r e f s .

2, 13, 14).

The p r e p a r a t i o n o f medium p o r e r e f e r e n c e m o l e c u l a r sieves, LZ-105 z e o l i t e and s i l i c a l i t e , have a l s o been d e s c r i b e d elsewhere ( r e f s . 15, 16). For 1-hexene i s o m e r i z a t i o n and f o r a c i d c a t a l y z e d C8 a r o m a t i c r e a c t i o n s a l l m o l e c u l a r s i e v e s were e v a l u a t e d i n t h e i r c a l c i n e d ,

C8 aromatics,

the study o f

selected

SAPO m o l e c u l a r

exchanged o r steam t r e a t e d as n o t e d i n T a b l e I V . used

in

paraffin

interconversions, platinum-loaded

the

cyclizationlisomerization calcined

molecular

sieve

c h l o r i d e d gamma alumina powder.

powdered s t a t e .

For

s i e v e s were aluminum

For b i f u n c t i o n a l c a t a l y s t s and

ethylbenzene-xylene

powder

was

mixed

with

These m i x t u r e s were t h e n

bound u s i n g s i l i c a s o l and e x t r u d e d t o f o r m 1/16" e x t r u d a t e s which were d r i e d and c a l c i n e d a t 500°C.

The b i f u n c t i o n a l c a t a l y s t s were p r e p a r e d t o c o n t a i n

about 0.5% p l a t i n u m and about 40 t o 50% SAPO m o l e c u l a r s i e v e i n t h e f i n i s h e d catalysts. Cata 1ys t Eva1u a t ion The powdered m o l e c u l a r

sieves

were e v a l u a t e d f o l l o w i n g t h e t r e a t m e n t

d e s c r i b e d above, w i t h o u t f u r t h e r a c t i v a t i o n .

C8

aromatic

isomerization

tests

continuous f l o w microreactors.

were

The 1-hexene i s o m e r i z a t i o n and

conducted

in

tubular,

fixed

bed,

The c a t a l y s t bed c o n t a i n e d one gram m o l e c u l a r

3

s i e v e powder and one t o t h r e e grams o f s i m i l a r l y s i z e d q u a r t z c h i p s used as diluent.

The r e a c t o r was heated t o t h e chosen r e a c t i o n temperatures i n a

fluidized

sand

bath,

and

the

r e a c t i o n t e m p e r a t u r e was

monitored b y

a

Typical runs l a s t e d 3 t o 5 hours

thermocouple .located i n t h e c a t a l y s t bed.

d u r i n g which samples were c o l l e c t e d e v e r y 30 minutes. P a r a f f i n c y c l i z a t i o n and i s o m e r i z a t i o n s t u d i e s were a l s o conducted i n t h e m i c r o r e a c t o r system. The f e e d used i n t h i s s t u d y was t e c h n i c a l grade n-hexane c o n t a i n i n g 87% n-hexane, 9% methylcyclopentane and 4% isopentanes. T y p i c a l l y about 0.35 g o f ground e x t r u d a t e s (20/80 mesh) were mixed w i t h quartz

c h i p s and loaded t o t h e r e a c t o r .

The r e a c t o r was heated t o t h e

r e a c t i o n temperature i n f l o w i n g hydrogen, p r i o r t o hexane f e e d i n t r o d u c t i o n . Runs l a s t e d f o r 24 hours and samples were c o l l e c t e d o n l y a f t e r 20 h o u r s on feed t o p e r m i t c a t a l y s t l i n e - o u t .

L i q u i d and gaseous p r o d u c t s were c o l l e c t e d

and analyzed as d e s c r i b e d above. The

bifunctional

platinum

-

SAP0

catalysts

were

evaluated

for

C8

a r o m a t i c r e a c t i o n s i n t h e presence o f hydrogen i n bench s c a l e r e a c t o r s . T y p i c a l l y , 25 t o 50 cc c a t a l y s t e x t r u d a t e s were d i l u t e d w i t h about f o u r volumes of s i m i l a r l y s i z e d q u a r t z chips, and p l a c e d i n a 1 1/4" ID r e a c t o r w i t n q u a r t z c h i p s placed i n b o t h end zones.

Feed which c o n s i s t e d o f e i t h e r

17% ethylbenzene + 83% m-xylene o r 40% ethylbenzene + 60% m-xylene was t h e n pumped over

t h e c a t a l y s t bed.

p r o d u c t s were c o l l e c t e d d a i l y .

Bench s c a l e r u n s l a s t e d s e v e r a l days and Both gas and l i q u i d p r o d u c t s were q u a n t i f i e d

and analyzed and m a t e r i a l balances were determined.

T y p i c a l l y t h e s e balances

were w i t h i n 2% o f c l o s u r e . The r e a c t i o n c o n d i t i o n s f o r a l l c a t a l y s t t e s t s a r e g i v e n a l o n g w i t h t h e t e s t r e s u l t s i n Tables I t o V. RESULTS A N D DISCUSSION Reactions o f O l e f i n s Olefins

p l a y a key r o l e as

intermediates

r e f i n i n g and petrochemical r e a c t i o n s .

Therefore,

i n a number o f

petroleum

t o b e t t e r understand t h e

f u n c t i o n and u t i l i t y o f aluminophosphate-based c a t a l y s t s , i t i s d e s i r a b l e t o examine t h e i r c a t a l y t i c c h e m i s t r y w i t h model o l e f i n s .

As mentioned above,

t h e s i l icoaluminophosphate m o l e c u l a r s i e v e s have a l r e a d y been r e p o r t e d t o be a c t i v e f o r o l i g o m e r i z a t i o n o f l i g h t o l e f i n s t o g a s o l i n e range p r o d u c t s ( r e f . 11).

The r e s u l t s o f t h a t s t u d y a r e reproduced i n T a b l e I which p r e s e n t s

conversion and s e l e c t i v i t y d a t a f o r p r o p y l e n e o l i g o m e r i z a t i o n t o l i q u i d products. These d a t a were o b t a i n e d u s i n g l a r g e , medium and s m a l l - p o r e SAPO's and medium pore r e f e r e n c e LZ-105 z e o l i t e .

4

TABLE I Vapor Phase P r o p y l e n e 01 i g o m e r i z a t i o n M o l e c u l a r Sieve P o r e Size, A Run Temperature, "F Pressure, p s i g P r o p y l ene WHSV Time on Stream,hr. p r o p y l e n e Conversion, % C5+ S e l e c t i v i t y a a)

SAPO-5 8 700 25 0.98 4.3 0

SAPO- 11 6 700 25 0.94 4.2 86.3 77.0

SAPO-3 1 1 700 50 1.04 5.5 76.2 82.7

SAPO-34 4.3 700 25 0.53 2.33 41.6 19.5

LZ- 105 6 703 25 0.90 3.5 81.6 37.2

C5+ S e l e c t i v i t y = (C5+ y i e l d , wt%)/(C3= c o n v e r s i o n , wt%)x100. The

data

show

that

the

l a r g e pore

SAPO-5

with

a

undirectional

non

i n t e r s e c t i n g channel system ( r e f . 17) was i n a c t i v e f o r o l i g o m e r i z a t i o n b y t h e t i m e t h e f i r s t sample had been taken. a c t i v i t y f o r butane c r a c k i n g ( r e f .

2),

Since SAPO-5 e x h i b i t e d s i g n i f i c a n t t h e lack o f oligomerization a c t i v i t y

was a t t r i b u t e d t o r a p i d c a t a l y s t coking, r e s u l t i n g i n d e a c t i v a t i o n . The s m a l l p o r e SAPO-34 h a v i n g a c r y s t a l s t r u c t u r e analogous t o c h a b a z i t e was

also

ineffective for

c o n v e r s i o n was observed,

propylene oligomerization. most o f

While 40% p r o p y l e n e

the products consisted o f ethylene

butenes, w i t h o n l y 20% s e l e c t i v i t y t o l i q u i d p r o d u c t s .

and

L a r g e r o l i g o m e r s were

c o n c e i v a b l y formed i n t h e cages o f t h e -34 c r y s t a l s t r u c t u r e b u t c o u l d n o t escape through t h e m o l e c u l a r s i e v e ' s s m a l l p o r e openings. products

observed,

were

p r o p y l e n e oligomers.

presumably

formed

by

the

The l i g h t o l e f i n

cracking

of

trapped

T h i s s c r a m b l i n g o f l i g h t o l e f i n s b y SAPO-34 was a l s o

observed by K a i s e r ( r e f . 12). I n c o n t r a s t t o SAPO-5 and SAPO-34, exhibited products.

significant While

oligomerization

the

s t r u c t u r e o f SAPO-11

structure

of

t h e medium p o r e SAPO-11 and SAPO-31 activity

the

has been r e p o r t e d .

and s e l e c t i v i t y t o

SAPO-31

is

as

yet

liquid

unknown,

the

I t comprises u n i d i r e c t i o n a l ,

non

i n t e r s e c t i n g channels formed by 10 member oxygen r i n g s ( r e f . 17). Conversions as h i g h as 86%, with C5+ p r o d u c t s e l e c t i v i t i e s as h i g h as 83%, were r e p o r t e d under t h e s c r e e n i n g c o n d i t i o n s .

The performance o f t h e medium p o r e SAPO's

a l s o d i f f e r e d s i g n i f i c a n t l y from t h a t o f t h e medium p o r e z e o l i t e r e f e r e n c e , LZ-105,

which a l s o achieved h i g h p r o p y l e n e conversion,

b u t a t o n l y 37% C5+

selectivity. The LZ-105 i s s t r u c t u r a l l y r e l a t e d t o ZSM-5 b u t i s p r e p a r e d w i t h o u t an o r g a n i c template. The l i q u i d p r o d u c t s formed over LZ-105 were h i g h l y aromatic,

i n c o n t r a s t t o t h e SAPO p r o d u c t s which were p r e d o m i n a n t l y

o l e f i n i c . Furthermore, t h e major gas p r o d u c t formed over LZ-105 c o n s i s t e d o f l i g h t paraffins.

The LZ-105

preponderance

hydrogen

of

o l i g o m e r i z a t e underwent

p r o d u c t d i s t r i b u t i o n was

transfer

secondary

reactions reactions,

in

which

attributed t o olefin

presumably o v e r

feed

strong

the and acid

5

s i t e s , t o produce l i g h t p a r a f f i n s and aromatics.

It was concluded t h a t , t h e

medium p o r e SAPO'S l a c k e d t h e a c i d s t r e n g t h r e q u i r e d t o c a t a l y z e h y d r i d e s h i f t r e a c t i o n s , and p o s s i b l y l a c k e d s p a t i a l r e q u i r e m e n t s t o f o r m t h e b u l k y t r a n s i t i o n s t a t e s e n v i s i o n e d f o r t h e s e h y d r i d e s h i f t r e a c t i o n s ( r e f . 11).

This lack

of h y d r i d e s h i f t a c t i v i t y r e s u l t e d i n h i g h s e l e c t i v i t y t o o l e f i n i c g a s o l i n e .

In t h e p r e s e n t study, t h e r e a c t i o n s o f 1-hexene as c a t a l y z e d b y a number of t h e s e m o l e c u l a r s i e v e s a r e summarized i n T a b l e 11. presented for

large,

medium

and

small

pore

As b e f o r e , d a t a a r e

SAPO's.

The

influence

of

t r a n s i t i o n metal framework elements i s a l s o e x p l o r e d w i t h s e l e c t e d MeAPO and

In a d d i t i o n t o o l i g o m e r i z a t i o n and h y d r i d e t r a n s f e r

MeAPSO m o l e c u l a r s i e v e s . reactions

observed

with

propylene

feed,

double

bond

and

skeletal

i s o m e r i z a t i o n s , c y c l i z a t i o n and c r a c k i n g a r e a l s o p o s s i b l e u s i n g 1-hexene as model r e a c t a n t , TABLE I 1 Reactions o f I-Hexene over A1 uminophosphate-Based M o l e c u l a r Sieves Run C o n d i t i o n s : Run Temperature 650°F Pressure 40 p s i g WHSV 5.5 l / h r M o l e c u l a r Sieve Pore Size, A T o t a l Conversion,% Selectivities: Double Bond Isomerization, % Skel e t a 1 Isomerization, % Oligomerization, % Cracking, %

SAPO -5 8

SAPO -11 6

FAPO -11 6

MnAPO -11 6

SAPO -31 7

FAPO -31 7

85.1

84 .5

90.1

89.6

86.0

89.1

94.5

93.7

79.1

46.2

22.1

28.0

82.2

42.5

43.2

2.4

10.9 5.6 3.2

41.9 4.3 3.3

70.6 2.4 1.5

63.6 0.9 1.9

14.3 1.7 0.9

52.8 0.9 1.3

44.6 4.1 2.6

12.2 55.1 25.6

MnAPSO -31 7

LZ-105 6

As w i t h propylene, t h e medium p o r e SAPO's a r e again q u i t e a c t i v e and a l s o quite selective.

Thus,

SAPO-11 gave over 90% 1-hexene conversion w i t h over

90% s e l e c t i v i t y t o isomerized products, h a l f o f which were s k e l e t a l isomers. It i s

important t o note t h a t

medium p o r e SAPO-11

i s s e v e r a l o r d e r s of

magnitude more coke r e s i s t a n t than t h e l a r g e p o r e SAPO-5. minutes

on

hexene

feed,

the

SAPO-5

was

catalytically

A f t e r o n l y 30 i n a c t i v e whereas

i s o m e r i z a t i o n a c t i v i t y w i t h SAPO-11 remained unchanged t h r o u g h o u t t h e t h r e e hour l o n g m i c r o - s c r e e n i n g t e s t .

It i s envisioned t h a t

t h e enhanced coke

r e s i s t a n c e o f t h e medium pore SAPO-11 i s due t o a p r o d u c t shape s e l e c t i v i t y . Due t o s p a t i a l c o n s t r a i n t s w i t h i n t h e SUPO-11 s t r u c t u r e , b u l k y coke p r e c u r s o r s a r e formed a t a g r e a t l y reduced r a t e r e l a t i v e t o t h e i r r a t e o f f o r m a t i o n i n

6

U n t i l now t h i s r e s i s t a n c e t o coke formation has o n l y been observed

SAPO-5.

w i t h t h e medium pore ZSM type molecular sieves ( r e f . 18). Under t h e m i l d e r c o n d i t i o n s o f t h i s screening s t u d y w i t h SAPO-11, l i t t l e o l i g o m e r i z a t i o n activity

was

observed,

but

importantly,

almost

no

cracking

of

hexene

occurred. I n c o n t r a s t , under i d e n t i c a l t e s t c o n d i t i o n s , t h e z e o l i t e r e f e r e n c e LZ-105 had v e r y h i g h a c t i v i t y f o r both o l i g o m e r i z a t i o n and cracking, f o r m i n g over 30% l i g h t products.

Most o f t h e isomerized hexene o l e f i n s were consumed

i n these secondary r e a c t i o n s .

The h i g h i s o m e r i z a t i o n s e l e c t i v i t y observed

w i t h t h e medium pore SAPO's i s probably a t t r i b u t a b l e t o s i g n i f i c a n t l y m i l d e r a c i d s t r e n g t h than t h a t possessed b y the r e f e r e n c e z e o l i t e c a t a l y s t . The i n c o r p o r a t i o n o f t r a n s i t i o n elements i n t o the c r y s t a l s t r u c t u r e o f medium pore aluminophosphate molecular sieves enhances s k e l e t a l i s o m e r i z a t i o n selectivity

even

beyond

that

with

observed

the

SAPO's.

Thus,

the

s i l icoaluminophosphate SAPO-11 gives 42% conversion t o s k e l e t a l isomers w i t h 3% cracked product w h i l e t h e same aluminophosphate c r y s t a l phase c o n t a i n i n g manganese

as

a

framework

constituent,

MnAPO-11,

i s o m e r i z a t i o n w i t h o n l y 2% cracked product.

gives

64%

skeletal

The i r o n c o n t a i n i n g FAPO-11 was

even more a c t i v e and s e l e c t i v e w i t h 71% and 1.5% i s o m e r i z a t i o n and c r a c k i n g a c t i v i t i e s , respectively.

S i m i l a r trends can be seen f o r t h e manganese and

i r o n s u b s t i t u t e d aluminophosphates w i t h t h e -31 s t r u c t u r e . P a r a f f i n Reactions The dehydrocycl i z a t i o n o f p a r a f f i n s r e p r e s e n t s a v e r y i m p o r t a n t c l a s s o f reactions

occurring

dehydrocyclization aromatics.

low

in

the

gasoline

octane

paraffins

converted

to

Through

high

octane

isomers t y p i c a l l y have v e r y s i g n i f i c a n t l y enhanced octane

numbers r e l a t i v e t o normal p a r a f f i n s . very

are

process.

P a r a f f i n i s o m e r i z a t i o n a l s o boosts g a s o l i n e octane i n r e f o r m i n g

s i n c e branched are

reforming

often

accompanied

by

D e h y d r o c y c l i z a t i o n and i s o m e r i z a t i o n

undesirable

cracking

reactions

enhancing

product octane a t t h e expense o f g a s o l i n e y i e l d . Shape s e l e c t i v e c r a c k i n g can enhance octane by c r a c k i n g away t h e low octane p a r a f f i n s t o form gas. The intermediacy o f o l e f i n s i n these r e a c t i o n s has been p r e v i o u s l y demonstrated ( r e f . 19). A simp1 i f i e d mechanism f o r t h e dehydrocycl i z a t i o n , i s o m e r i z a t i o n and c r a c k i n g o f n hexane i s summarized below: Pt

nG

-

nG--

CYCLO ~e

-

LIGHT OLEFINS

BENZENE LIGHT PARAFFINS

7

Here,

f i r s t o l e f i n i c i n t e r m e d i a t e s a r e generated over p l a t i n u m .

These

i n t e r m e d i a t e s a r e e i t h e r cracked t o f o r m l i g h t e r o l e f i n s o r c y c l i z e d and isomerized over t h e a c i d i c c h l o r i d e d alumina.

The o l e f i n s and naphthenes

thus formed a r e f i n a l l y dehydrogenated over t h e p l a t i n u m t o f o r m p a r a f f i n s Z e o l i t i c a c i d s such as m o r d e n i t e ( r e f . 20) and ZSM-5

and aromatics.

( r e f . 21)

have been s u b s t i t u t e d f o r t h e c h l o r i d e d alumina as a c i d c a t a l y s t components. I n t h e p r e s e n t study, m i x t u r e s o f supported p l a t i n u m and aluminophosphate based m o l e c u l a r s i e v e s have been t e s t e d f o r n-hexane rearrangement r e a c t i o n s under

reforming

conditions

(900°F,

200

psig).

Results

are

summarized

g r a p h i c a l l y i n F i g u r e s 1 and 2, where s e l e c t i v i t i e s a r e p l o t t e d as f u n c t i o n s Of

n-hexane conversion.

Data a r e presented f o r t h e l a r g e , medium and s m a l l

pore SAPO m o l e c u l a r s i e v e s mixed w i t h

a Pt-alumina

catalyst.

Data f o r

p l a t i n u m mixed w i t h c h l o r i d e d alumina o r mixed w i t h s i l i c a l i t e a r e p r e s e n t e d f o r reference.

I n F i g u r e 1, t h e r a t i o o f iso-hexanes t o cracked p r o d u c t s i s

p l o t t e d a g a i n s t conversion. pore

SAPO-5

however,

is

less

The c a t a l y s t c o n s i s t i n g o f p l a t i n u m and l a r g e

active

i t appears s i m i l a r

distribution of pore SAPO-34

than

reference

i n selectivity,

platinum-chlorided

i n t h a t i t produces a s i m i l a r

isomerized and cracked p r o d u c t s .

i s quite active f o r

alumina;

Mixed p l a t i n u m and s m a l l

hexane conversions

but

selectivity for

isomerized hexanes i s s i g n i f i c a n t l y lower than observed w i t h t h e r e f e r e n c e , and

a

significant

observed.

increase

in

the

amount o f

These r e s u l t s a r e t o be expected.

l i g h t cracked

products

is

SAPO-34 w i t h t h e c h a b a z i t e - t y p e

s t r u c t u r e possesses cages i n which t h e l a r g e hexene isomers can form; however, due t o t h e small pore opening o f t h e -34 s t r u c t u r e ,

t h e isomers once formed

can n o t escape w i t h o u t c r a c k i n g t o l i g h t e r p r o d u c t s .

The n o b l e m e t a l - l o a d e d

medium pore

SAPO's

-11

and

-41

exhibit

excellent

hexane

isomerization

s e l e c t i v i t i e s when a p p l i e d t o g e t h e r w i t h p l a t i n u m , p r o d u c i n g 2 t o 4 t i m e s t h e amount o f isomers compared t o r e f e r e n c e p l a t i n u m - c h l o r i d e d alumina c a t a l y s t . I n contrast, mixture,

t h e medium pore s i l i c a l i t e

and

supported p l a t i n u m c a t a l y s t

w h i l e a c h i e v i n g s i g n i f i c a n t l y h i g h e r n-hexane

conversion,

i s far

l e s s s e l e c t i v e than t h e medium p o r e SAPO c a t a l y s t m i x t u r e and t h e c h l o r i d e d alumina-platinum

reference,

p r o d u c i n g a l a r g e amount o f cracked p r o d u c t s .

S i m i l a r s e l e c t i v i t y t r e n d s a r e observed f o r t h e dehydrocycl i z a t i o n r e a c t i o n s of n-hexane.

Thus i n F i g u r e 2 t h e benzene t o l i g h t p r o d u c t s r a t i o i s p l o t t e d

a g a i n s t conversion f o r t h e same s e t o f c a t a l y s t s ,

and again t h e medium p o r e

SAPO's e x h i b i t s u p e r i o r s e l e c t i v i t y t o b o t h r e f e r e n c e m a t e r i a l s and t o b o t h l a r g e and small pore SAPO c a t a l y s t systems.

These r e s u l t s a r e i n complete

agreement w i t h t h e hexene i s o m e r i z a t i o n d a t a d e s c r i b e d above,

wherein t h e

medium pore SAPO's show s i g n i f i c a n t l y reduced a c t i v i t y f o r c r a c k i n g r e a c t i o n s while maintaining h i g h skeletal isomerization a c t i v i t y .

8 12r

11

-

A A

10. 0

A

!i 5 *9 c 9-

7-

x

I

'i

2

+n +

1-

Q o A 1

.

1

1

1

,

Fig. 1 . I s o m e r i z a t i o n / C r a c k i n g S e l e c t i v i t y R a t i o p l o t t e d as a f u n c t i o n o f n-hexane conversion: ASAPO- 11 , X SAPO-41, +SAPO-5, OSAPO-34, A S i l i c a l i t e and O P t / c h l o r i d e d - a l u m i n a r e f e r e n c e .

+

I

.75-

A

x x

A

2

I I

s

A

.50-

z W

++

.25W

m

0

I

0

I

10

1

1

.

A

,

30 40 50 60 7 0 80 n - HEXANE CONVERSION, WT% 20

I

90

F i g . 2. D e h y d r o c y c l i z a t i o n / C r a c k i n g S e l e c t i v i t y R a t i o p l o t t e d as a f u n c t i o n of n-hexane conversion: ASAPO-11, XSAPO-41, +SAPO-5, OSAPO-34, A S i l i c a l i t e and O P t / c h l o r i d e d - a l u m i n a r e f e r e n c e .

9

Aromatic Reactions I n a d d i t i o n t o reforming,

t h e i s o m e r i z a t i o n o f C8

a r o m a t i c s t o produce

para-xylene i s another area where o l e f i n i c i n t e r m e d i a t e s may p l a y a s i g n i f i c a n t m e c h a n i s t i c r o l e . The p r o d u c t i o n o f p a r a - x y l e n e i s o f i n t e r e s t t o t h e petrochemical i n d u s t r y because o f i t s use as monomer i n p o l y e s t e r p r o d u c t i o n . I n a d d i t i o n t o C a r o m a t i c i s o m e r i z a t i o n , t h e r e a r e a number o f i m p o r t a n t 8 r o u t e s t o para-xylene i n c l u d i n g t h e a l k y l a t i o n o f t o l u e n e w i t h methanol and the disproportionation o f

toluene.

The c a t a l y t i c

p r o p e r t i e s o f t h e SAP0

m o l e c u l a r s i e v e s f o r t o l u e n e m e t h y l a t i o n r e a c t i o n s have been d e s c r i b e d ( r e f . 11).

While b o t h l a r g e and medium pore SAPO's were a c t i v e f o r t h e a l k y l a t i o n

reaction,

t h e medium pore m a t e r i a l s were d i s t i n g u i s h e d b y r e m a r k a b l y h i g h

s e l e c t i v i t y f o r methylation reactions, with disproportionation o f the toluene feed r e p r e s e n t i n g l e s s than 2% o f t h e t o t a l conversion. pore SAPO-5 had n e a r l y 60% d i s p r o p o r t i o n a t i o n

By comparison, l a r g e

s e l e c t i v i t y and t h e z e o l i t e

r e f e r e n c e LZ-105 had n e a r l y 80% d i s p r o p o r t i o n a t i o n s e l e c t i v i t y . d i s p r o p o r t i o n a t i o n a c t i v i t y o f t h e medium p o r e SAPO's, m i l d acid character,

The v e r y low

attributed t o their

r e s u l t e d i n reduced l o s s e s o f t o l u e n e t o benzene and

increased xylene y i e l d s r e l a t i v e t o LZ-105 and SAPO-5. In

the

present

study,

silicon

and

transition

metal

substituted

aluminophosphate m o l e c u l a r s i e v e s have a l s o been e v a l u a t e d f o r a c t i v i t y and selectivity for

p r o d u c t i o n v i a C8

para-xylene

commercial p r a c t i c e ,

C8

and

naphtha

from

fraction

pyrolysis

aromatic isomerization.

In

aromatic c u t s a r e o b t a i n e d f r o m r e f o r m a t e g a s o l i n e streams.

o f ethylbenzene which

Both

feeds

contain

a

significant

i s d i f f i c u l t t o s e p a r a t e f r o m xylenes

by

and must be c a t a l y t i c a l l y c o n v e r t e d t o o t h e r p r o d u c t s .

p h y s i c a l techniques,

T h i s c a t a l y t i c conversion can b e accomplished b y one o f two c o m n e r c i a l l y a v a i l a b l e approaches. as ZSM-5

(ref.

22)

I n one approach,

m o n o - f u n c t i o n a l a c i d c a t a l y s t s such

isomerize xylenes and a l s o c o n v e r t ethylbenzene t o non

aromatics by selective ethyl group disproportionation. '8 D i s p r o p o r t i o n a t i o n o f xylenes t o non C8 a r o m a t i c s i s a competing s i d e r e a c t i o n l o w e r i n g t h e u l t i m a t e para-xylene y i e l d . not

convert

catalysts

the

ethyl-benzene

to

xylenes.

To

A c i d c a t a l y s i s a l o n e can this

end,

c o n t a i n i n g b o t h a hydrogenation-dehydrogenation

f u n c t i o n such as

p l a t i n u m as w e l l as an a c i d i c f u n c t i o n such as mordenite typically

been

hydrogenated

over

employed. Pt

to

In

the

latter

ethylcyclohexene

approach,

which

is

bifunctional

(ref.

2 3 ) , have

ethylbenzene

then

isomerized

is to

dimethylcyclohexene o v e r t h e a c i d c a t a l y s t f u n c t i o n , and f i n a l l y c o n v e r t e d t o xylenes b y dehydrogenation over t h e platinum.

10

2Hzf

CRACKED PRODUCTS

Conceptually, yields,

this

b u t since

route

offers

naphthenic

the

possibility

intermediates

of

are present,

enhanced

xylene

s i g n i f i c a n t acid

c a t a l y z e d r i n g opening and y i e l d l o s s o f a r o m a t i c s a r e a l s o p o s s i b l e . review o f a v a i l a b l e patent l i t e r a t u r e data

(refs.

because o f these u n d e s i r a b l e s i d e r e a c t i o n s , isomerization

yields

about

the

same

22,

23b) suggests

A

that

t h e b i f u n c t i o n a l approach t o

amount

of

xylene

as

does

the

monofunctional route.

C, Aromatic Reactions Witnout Hydrogen v -

I n t h e p r e s e n t study,

t h e alumino-phosphate

m o l e c u l a r s i e v e s have been

used a l o n e and w i t h added p l a t i n u m and hydrogen t o i s o m e r i z e C feeds.

8

aromatic

In an i n i t i a l s c r e e n i n g s t u d y , a s e r i e s o f l a r g e t o medium p o r e s i z e

molecular

sieves

rearrangements a t conditions

all

isomerization xylene

were

evaluated

1000°F

without

molecular

sieves

o f m-xylene

isomers,

while

trimethylbenzenes

varies

for

catalytic

added metal

activity

for

and hydrogen.

evaluated

give

m-xylene

Under

essentially

these

complete

f e e d t o a thermodynamic e q u i l i b r i u m m i x t u r e of

the

disproportionation

significantly.

summarized i n T a b l e 111 and i n F i g u r e 3,

The

activity

results

to

of

toluene

this

study

and are

where x y l e n e d i s p r o p o r t i o n a t i o n

a c t i v i t y i s p l o t t e d as a f u n c t i o n o f m o l e c u l a r s i e v e p o r e s i z e .

I n general,

a rough t r e n d can be seen i n which t h e m o l e c u l a r s i e v e s with l a r g e r p o r e s i z e s a r e more a c t i v e f o r t h i s u n d e s i r a b l e s i d e r e a c t i o n . chosen

screening

conditions,

SAPO-5,

MAPO-5

and MAPO-36,

m o l e c u l a r s i e v e s w i t h a p p r o x i m a t e l y 8 angstrom p o r e s i z e s , to

22

%

disproportionation

while

SAPO-11,

Thus under t h e

MAPO-11

all

l a r g e pore

c a t a l y z e f r o m 12 and

SAPO-41

a p p r o x i m a t e l y 6 angstrom pores s u f f e r o n l y 2 t o 7 % x y l e n e l o s s e s .

with These

r e s u l t s a r e c o n s i s t e n t w i t h t h e concept o f t r a n s i t i o n s t a t e shape s e l e c t i v i t y where a b u l k y ,

bimolecular

i n t e r a c t i o n o f two xylenes t o f o r m t o l u e n e and

t r i m e t h y l b e n z e n e i s d i f f i c u l t t o a c h i e v e i n t h e a p p r o x i m a t e l y 6 angstrom s i z e channels.

11

TABLE 111 m-Xylene Reactions Catalyzed by A1 uminophosphate-Based Molecular Sieves Run Conditions: Run Temperature Pressure WHSV

1000°F 100 p s i g 5.6 l / h r . a

Molecular Sieve SAPO-5 MAPO-5 MAPO-36 SAPO-3 1 SAPO-4 1 SAPO- 11 MAPO- 1 1

I:

Pore Size 0.8 0.8 0.8 0.65 0.6 0.6 0.6

b Pore Volume 0.31 0.17 0.22 0.16 0.16

m-Xyl ene Dispropor t ionat ion, % Conversion 20.7 22.4 12.6 15.1 7.1 3.2 1.8

Determined by McBain Bakr g r a v i m e t r i c adsorption s t u d i e s ( r e f . 3). Determined by water adsorption a t s a t u r a t i o n ( r e f . 3). 3oL

z

0

2 -

0 24

1 0

E

g18-

* z

0 v)

212-

> z

8w z

2

6-

X

#

01

I

0.8

0.7

0.8

0.9

PORE SIZE, NM

Fig. 3. Xylene losses due t o d i s p r o p o r t i o n a t i o n are a f u n c t i o n o f molecular sieve c a t a l y s t ' s pore s i z e . I n t h e next phase o f t h e present study, sieves were evaluated f o r m-xylene feed.

the

several medium pore molecular

c a t a l y t i c performance with an ethylbenzene and

Again, t h e molecular sieves were t e s t e d with no added metal

12

o r hydrogen.

Several of

t h e s e aluminophosphate based m o l e c u l a r s i e v e s d i d The r e s u l t s o f t h i s s t u d y

c o n t a i n t r a n s i t i o n m e t a l s as framework elements. are summarized i n Table I V and F i g u r e 4.

From t h e Table i t can be seen t h a t

a l l m o l e c u l d r s i e v e s y i e l d p a r a - x y l e n e i n amounts e q u i v a l e n t t o thermodynamic equilibrium.

Surprisingly,

the

cobalt

and manganese-containing

molecular

s i e v e s w i t h t h e -31 t y p e s t r u c t u r e d i d n o t promote t h e e q u i l i b r a t i o n o f meta t o ortho-xylene,

so t h a t v e r y h i g h p a r a / o r t h o s e l e c t i v i t i e s were observed.

Since SAPO-31 w i t h i d e n t i c a l framework s t r u c t u r e does n o t e x h i b i t t h e h i g h para and low o r t h o - x y l e n e

s e l e c t i v i t y observed w i t h t h e MeAPSO-31 m o l e c u l a r

s i e v e s , t h e i r h i g h s e l e c t i v i t y m i g h t p o s s i b l y be i n t e r p r e t e d as p r o d u c t shape selectivity

due

to

restricted

pore

size.

Obviously

the

Mn+2 framework

c a t i o n s a r e l a r g e r than t h e s i l i c o n and aluminum c a t i o n s t h e y a r e r e p l a c i n g , and t h i s c o u l d c o n c e i v a b l y r e s u l t i n r e s t r i c t i o n s i n t h e m o l e c u l a r

sieve

channels.

"plug

gauge-sized"

However,

McBain-Bakr

g r a v i m e t r i c adsorption

studies with

molecules suggest t h a t MeAPSO-31 I s have p o r e s i z e s and volumes

s i m i l a r t o those o f t h e m e t a l - f r e e SAPO-31, which does n o t appear t o b e p a r a s e l e c t i v e ( r e f . 3 ) . Furthermore, SAPO-11 w i t h s l i g h t l y s m a l l e r p o r e s i z e t h a n CoAPSO-31 and MnAPSO-31 does n o t show n e a r l y t h e p a r a s e l e c t i v i t y observed w i t h the t r a n s i t i o n metal-containing structure.

m o l e c u l a r s i e v e s w i t h t h e -31

An a l t e r n a t e e x p l a n a t i o n i s needed.

crystal

I t may b e t h a t t h e framework

t r a n s i t i o n metal i o n s i n t h e s e m o l e c u l a r s i e v e s e x e r t a chemical i n f l u e n c e on the

intermediates

para-isomer.

in

Alternately,

isomerization,

favoring

the

formation

of

the

a c i d s i t e s may be u n i q u e l y l o c a t e d i n t h e MeAPSO

m o l e c u l a r s i e v e s such t h a t access o f r e a c t a n t s and r e a c t i o n i n t e r m e d i a t e s t o these acid s i t e s i s s p a t i a l l y constrained, f a v o r i n g p a r a - s e l e c t i v i t y . TABLE I V m-XylenelEthylbenzene Reactions w i t h Medium Pore S i z e Aluminophosphate Based M o l e c u l a r Sieves Run C o n d i t i o n s : Run Temperature Pressure WHSV

800°F 100 p s i g 5.6 l / h r .

M o l e c u l a r Sieve SAPO- 11 SAPO-11 (Al'3 exchanged) SAPO-11 (Steam t r e a t e d ) SAPO-31 SAPO-31 (Steam t r e a t e d ) MnAPSO- 11 COAPSO-11 MnAPSO-31 COAPSO-31 LZ-105

P ar a/Or t h o Xylene R a t i o

:1.52 ; 0.78 1.56 0.88 1.81 3.59 3.06 0.99

%Para-Xyl ene Equilibration 96 102 63 100 102 104 91 120 111 100

% D i s p r o p o r t io n a t ion Xylenes Ethylbenzene 9.9 23.2 6.6 20.1 0.2 6 .O 31.6 56.3 1.7 10.4 5 .O 23.3 0.0 7.7 0.0 17.7 1.7 23.0 23.6 58.5

13

Figure 4 plots ethylbenzene vs xylene disproportionation activity for the same series of catalysts. Data were obtained at a range of conversions by varying reaction temperature. Again a1 1 catalysts were tested without added metal or hydrogen. Data obtained with medium pore zeolite reference LZ-105 are also presented for comparison. The MeAPSO-31 molecular sieves are again distinguished by superior selectivity. Thus at comparable ethylbenzene conversions, the CoAPSO and MnAPSO-31 molecular sieves exhibit the lowest activity for the undesirable xylene disproportionation while SAPO-11 and SAPO-31 are considerably less selective. Data obtained with LZ-105 is intermediate in selectivity. Again the enhanced selectivity observed with the MeAPSO-31 molecular sieves may be due to a transition metal specific influence on the reaction intermediates. Shape selective effects by themselves cannot explain differences between these materials and the transition metal-free SAPO's.

./ rn

J

6

13

20

27

% XYLENE LOSS

Fig. 4. Selectivity for ethylbenzene conversion plotted against xylene losses for A MeAPSO's, 0 LZ-105 and SAPO's.

14

C Aromatic -

R e a c t i o n s w i t h Hydrogen

I n a final

phase o f t h e c u r r e n t s t u d y , c a t a l y s t s c o n s i s t i n g o f s e l e c t e d

SAPO's and s u p p o r t e d p l a t i n u m have been e v a l u a t e d i n t h e presence o f hydrogen for

C8 a r o m a t i c i s o m e r i z a t i o n .

bifunctional

Two c a t a l y s t s were prepared,

one c o n t a i n i n g 40% o f t h e i n t e r m e d i a t e p o r e SAPO-11 and t h e o t h e r c o n t a i n i n g 40% o f l a r g e pore SAPO-5.

Both c a t a l y s t s were prepared t o c o n t a i n about 0.6% The c a t a l y s t s were e v a l u a t e d a t 8OO0F,

p l a t i n u m supported on alumina.

185

p s i g and a t a space v e l o c i t y o f 1 and a hydrogen t o hydrocarbon r a t i o o f 14. The f e e d used f o r t h e s e t e s t s c o n t a i n e d 17% e t h y l b e n z e n e and 83% m-xylene, simulating

C8

a

aromatic

cut

obtained

from

reformate

gasoline.

Each

c a t a l y s t was e v a l u a t e d f o r s e v e r a l days on stream, and a t t h e h i g h hydrogen/ hydrocarbon r a t i o employed, addition,

the

l i t t l e or

SAPO-11-containing

n o d e a c t i v a t i o n was

catalyst

ethylbenzene

+

effectiveness

i n c o n v e r t i n g ethylbenzene

60% m-xylene

feed

s i m i l a r t o a p y r o l y s i s naphtha C8

in

was

order

to

Typical

with

better

t o xylenes,

cut.

observed.

evaluated

a

In

40%

evaluate

and t o model

its

a feed

performance d a t a f o r each

c a t a l y s t a f t e r s e v e r a l h o u r s on t h e 17% e t h y l b e n z e n e f e e d a r e summarized i n Table V . formed

Performance i n d i c a t o r s were c a l c u l a t e d assuming t h a t t h e naphthenes during

processing

would

in

commercial

practice

be

recycled,

and

t h e r e f o r e t h e i r f o r m a t i o n would c o n t r i b u t e t o n e i t h e r e t h y l b e n z e n e c o n v e r s i o n nor t o xylene losses. A c c o r d i n g t o t h e t e s t s b o t h c a t a l y s t s promote near-complete

xylene

equilibration,

and

the

catalyst

containing

achieves h i g h e r ethylbenzene c o n v e r s i o n t h a n t h e SAPO-11 c a t a l y s t , 44% r e s p e c t i v e l y . However,

SAPO-5 68% and

t h e l a r g e p o r e m o l e c u l a r s i e v e i n c u r s n e a r l y 22%

x y l e n e l o s s e s w h i l e t h e SAPO-11 based c a t a l y s t a c t u a l l y produces 2.1% more xylenes than were p r e s e n t i n i t i a l l y i n t h e feed.

With SAPO-5 these l o s s e s

a r e due t o d i s p r o p o r t i o n a t i o n r e a c t i o n s p r o d u c i n g benzene, aromatics,

and a l s o t o non c y c l i c p r o d u c t f o r m a t i o n ,

t o l u e n e and C9+

suggesting s i g n i f i c a n t

r i n g opening and c r a c k i n g .

With t h e SAPO-11 c a t a l y s t

t h e r e i s much l e s s

disproportionation

and almost n o ring-opened

p a r a f f i n i c products

activity,

a r e observed. While t h e p r e s e n t s t u d y has n o t examined t h e performance o f z e o l i t e based catalysts,

Table

V

summarizes

patent

m o r a e n i t e and p l a t i n u m / a l u m i n a m i x t u r e . obtained

under

similar

conditions

literature

data

(ref.

23b)

for

a

Data f o r t h e P t and SAPO-11 m i x t u r e are

presented

for

comparison.

m o r d e n i t e c a t a l y s t i s s i g n i f i c a n t l y l e s s s e l e c t i v e t h a n SAPO-11,

The

g i v i n g 25.6%

ethylbenzene c o n v e r s i o n w i t h o n l y 0.5% n e t x y l e n e p r o d u c t i o n . The

data

obtained

with

high

ethylbenzene

feed

shows

even

more

d r a m a t i c a l l y t h e e f f i c i e n t c o n v e r s i o n o f e t h y l b e n z e n e t o xylenes o v e r t h e SAPO-11-containing c a t a l y s t .

Thus a t 23.6% ethylbenzene conversion,

a nearly

15

13% i n c r e a s e i n x y l e n e y i e l d i s observed. T h i s i n d i c a t e s t h a t ethylbenzene has been c o n v e r t e d w i t h 75% s e l e c t i v i t y t o xylene isomers. The r e m a i n i n g conversion was t o d i s p r o p o r t i o n a t i o n opening.

products w i t h

a g a i n almost n o r i n g

TABLE V Cg Aromatic I s o m e r i z a t i o n With B i f u n c t i o n a l C a t a l y s t s ~~

Molecular Sieve Component

b

SAPO-5

SAPO-11

SAPO-11

SAPO-11

40 800 185 14 1 17

40 800 185 14 1 17

40 840 250 8.3 2.9 17

40 800 165 14 1 40

Mordenite

a M o l e c u l a r Sieve Content, % Run Pressure, p s i g Run Temperature,"C H2/HC R a t i o WHSV Ethylbenzene i n Feed, % Approach t o p-xylene Equilibrium, % Ethylbenzene Conversion, % Net Xylene P r o d u c t i o n , % a) b)

94.9 67.9 -21.6

97.3 44.6 2.1

94.5 28.2 1.5

50 800 175 8 3.6 15.5

96.2 23.6 12.8

99.3 25.6 0.5

I n a d d i t i o n t o the q u a n t i t y o f molecular sieve l i s t e d , a l l c a t a l y s t s c o n t a i n e d 0.4-0.6% p l atinum. Data o b t a i n e d f r o m U.S. P a t e n t 4,255,606, Example 1.

CONCLUSIONS The medium p o r e aluminophosphate based m o l e c u l a r s i e v e s a r e a c t i v e and selective catalysts f o r reactions.

As

acid

a variety of

catalysts,

i m p o r t a n t hydrocarbon rearrangement

they

promote

olefin

isomerization

and

o l i g o m e r i z a t i o n w h i l e t h e y a r e s i g n i f i c a n t l y l e s s e f f e c t i v e a t t h e competing h y d r i d e t r a n s f e r and c r a c k i n g r e a c t i o n s . I n t h e r e a c t i o n s o f a r o m a t i c s , t h e medium pore aluminophosphates a r e again e f f e c t i v e f o r s k e l e t a l i s o m e r i z a t i o n b u t show low e t h y l group d i s p r o p o r t i o n a t i o n a c t i v i t y . bifunctional

catalysts,

As a c i d components i n

t h e y a r e s e l e c t i v e f o r p a r a f f i n and c y c l o p a r a f f i n

i s o m e r i z a t i o n w i t h low c r a c k i n g a c t i v i t y . These c a t a l y t i c p r o p e r t i e s c o n t r a s t s h a r p l y w i t h t h o s e o f medium p o r e z e o l i t e s such as LZ-105 and w i t h s i l i c a l i t e . considerably

less

active

than LZ-105

for

Thus, medium p o r e SAPO's a r e olefin,

paraffin

and a r o m a t i c

conversions when compared a t t h e same temperature. However, t h e y a r e more s e l e c t i v e f o r o l e f i n and p a r a f f i n i s o m e r i z a t i o n s when e v a l u a t e d a t comparable conversions

.

Not s u r p r i s i n g l y ,

t h e c a t a l y t i c p r o p e r t i e s o f medium p o r e aluminophos-

phates a l s o c o n t r a s t w i t h l a r g e pore aluminophosphate-based m o l e c u l a r s i e v e s of

similar

framework

composition.

With

olefinic

feeds,

the

l a r g e pore

molecular sieves d e a c t i v a t e v e r y r a p i d l y , presumably due t o p o r e p l u g g i n g b y

16

higher molecular weight products. more coke r e s i s t a n t . than 30 minutes,

SAPO-11 I s

With a r o m a t i c feeds, for

The medium p o r e SAPO's a r e d r a m a t i c a l l y

Under c o n d i t i o n s t h a t f u l l y d e a c t i v a t e SAPO-5 a c t i v i t y remains unchanged f o r

i n less

several

hours.

b o t h l a r g e and medium p o r e m o l e c u l a r s i e v e s a r e a c t i v e

a l k y l a t i o n and i s o m e r i z a t i o n .

However,

t h e l a r g e pore molecular sieves

a r e s i g n i f i c a n t l y more a c t i v e f o r t h e d i s p r o p o r t i o n a t i o n o f d i a l k y l a r o m a t i c s , i m p l y i n g t r a n s i t i o n s t a t e shape s e l e c t i v i t y f o r t h e medium p o r e m o l e c u l a r sieves.

I n bifunctional

catalysis

i n v o l v i n g o l e f i n i c intermediates,

large

pore m o l e c u l a r s i e v e s a r e more a c t i v e f o r c r a c k i n g and l e s s s e l e c t i v e f o r skeletal isomerization reactions. The c a t a l y t i c also

p r o p e r t i e s o f t h e aluminophosphate

influenced by

chemical

composition.

The

molecular

sieves are

introduction o f

transition

m e t a l s i n t o framework p o s i t i o n s enhances t h e a c t i v i t y and s e l e c t i v i t y f o r o l e f i n i s o m e r i z a t i o n r e l a t i v e t o t h e silicoaluminophosphates.

The t r a n s i t i o n

metal c o n t a i n i n g alurninophosphates a r e a l s o s u r p r i s i n g l y more s e l e c t i v e f o r

C8 a r o m a t i c rearrangements t h a n t h e c o r r e s p o n d i n g SAP0 m o l e c u l a r s i e v e s , an e f f e c t which can n o t b e a t t r i b u t e d s o l e l y t o improved shape s e l e c t i v i t y . The

enhanced

selectivities

observed

with

medium

pore

silico-

and

metalloaluminophosphates may, t o a l a r g e e x t e n t b e a t t r i b u t e d t o a u n i q u e combination o f m i l d a c i d i t y and shape s e l e c t i v i t y . and c r a c k i n g a c t i v i t y i n o l e f i n - m e d i a t e d acidity.

The

observed r e s i s t a n c e

selectivity t o

para-xylene

to

addition

constituents

to

these

appear

to

coke

deactivation

i n m e t h y l a t i o n and factors,

exert

a

and t h e enhanced

isomerization reactions

is

.

evidence o f shape-sel e c t ive c a t a l y s i s In

The l a c k o f h y d r i d e s h i f t

r e a c t i o n s i s suggestive o f m i l d

however, special

transition

chemical

metal

effect

on

framework catalytic

performance which appears t o be independent o f m o l e c u l a r s i e v e a c i d s t r e n g t h and

spatial

constraints.

manganese-containing

This

molecular

effect sieves

is as

evidenced

by

enhanced

selectivity

ethylbenzene d i s p r o p o r t i o n a t i o n i n t h e presence o f xylenes, para-selectivity size

i n xylene i s o m e r i z a t i o n .

than SAPO-11

as

judged b y

s e l e c t i v e f o r para-xylene to

a uniquely

molecular Alternately, metal,

sieve

for

and b y enhanced

"plug

gauge"

molecules

but

i s f a r more

and f o r ethylbenzene d i s p r o p o r t i o n a t i o n than t h e

'located with

and

Thus, MnAPSO-31 has a l a r g e r p o r e

SAPO-11 under comparable t e s t c o n d i t i o n s . due

cobalt

acid

site

special

and

T h i s enhanced s e l e c t i v i t y may b e

in

the

transition

unexpected

metal-containing

spatial

requirements.

i t may b e due t o a l i g a n d o r e l e c t r o n i c e f f e c t o f t h e t r a n s i t i o n

affecting

the

transition

disproportionation reactions.

states

in

aromatic

isomerization

and

17

REFERENCES 1 S.T. Wilson, B.M. Lok, C.A. Messina, T.R. Cannan, E.M. Flanigen, J. Am. Chem. SOC. 1982, 1146. Lok, C.A. Messina, R.L. Patton, R.T. Gajek, T.R. Cannan, E.M. 2 B.M. Flanigen, J. Am. Chem. SOC. 1984, 6092; U.S. Patent 4 440 871, 1984. 3 E.M. Flanigen, B.M. Lok, R.L. Patton, S.T. Wilson, I n New Developments i n Z e o l i t e Science and Technology; Y. Murakami, A. I i j i m a , J.W. Ward, Eds., Proceedings o f t h e 7 t h I n t e r n a t i o n a l Z e o l i t e Conference; E l s e v i e r , New York, 1986, p.103. 4 R.J. P e l l e t , P.K. Coughlin, M.T. S t a n i u l i s , G.N. Long, J.A. Rabo, U.S. Patent 4 666 875, 1987. Gortsema, R.J. P e l l e t , A.R. Springer, J.A. Rabo, G.N. Long, 5 F.P. Eur. P a t . Appl. 207 133, 1987. Gortsema, R.J. P e l l e t , A.R. 6 F.P. Springer, J.A. Rabo, G.N. Long, Eur. P a t . Appl. 185 329, 1986. 7 D.C. Garska, B.M. Lok, U.S. Patent 4 499 315, 1985. Long, J.A. Rabo, I n New Developments i n Z e o l i t e 8 R.J. P e l l e t , G.N. Y. Murakami, A. I i j i m a , J.W. Ward, Eds., Science and Technology; Proceedings o f t h e 7 t h I n t e r n a t i o n a l Z e o l i t e Conference; E l s e v i e r , New York, 1986, p. 843; 9 S.W. Kaiser, U.S. Patent 4 524 234, 1985. 10 S.k. Kaiser, Arabian J. Sci. Eng., 1985, 10(4),361-6; 1 1 G.N. Lonq, R.J. P e l l e t , J.A. Rabo, U.S. Patent 4 528 414, 1985: 12 S.W. K a i i e r , Eur. Pat; Appl. 142-156, 1985. 13 C.A. Messina, B.M. Lok, E.M. Flanigen U.S. Patent 4 544 143, 1985. 14 S.T. Wilson, E.M. Flanigen U.S. Patent 4 567 029, 1986. 15 R.W. Grose, E.M. Flanigen U.S. Patent 4 257 885, 1981. 16 R.W. Grose, E.M. Flaniqen U.S. Patent 4 061 724, 1977. Flanigen, J.J. - P l u t h , J.V. Smith, I n 17a J.M. Bennett, J.P. CGhen, E.M. I n t r a z e o l i t e Chemistry; ACS Symposium Series No. 218; American Chemical S o c i e t y : Washington, D.C., 1983; pp 109-18. b J.M. Bennett, J.V. Smith, 2. K r i s t . 1985, 171, 65-68. 18 D.E. Walsh, L.D. Rollman, J. Catal. 1979, 195-197. 19 G.A. M i l l s , H. Heinemann, T.H. M i l l i k e n , Oblad, A.G. Ind. Eng. Chem. 1953, 45, 134. 20 R.J. B e r t o l a c i n i , U.S. Patent 4 018 711, 1977. 21 C.M. Detz, L.M. F i e l d , U.S. P a t e n t 4 347 394, 1982. 22 W.O. Haag, D.H. Olson, U.S. Patent 3 856 871, 1974. 23a W.C. Carr, L.M.Polinski, S.G. Hindin, J.L.Kosco, U.S. Patent 4128 591, 1978. b H.F. Tse, U.S. Patent 4 255 606, 1981.

104,

106,


H.G. Karge, J. Weitkamp (Editors),Zeolites as Catalysts, Sorbents and Detergent Builders 0 1989 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands

CATALYTIC AND PHYSICAL PROPERTIES OF SILICON-SUBSTITUTED A1P04-5 MOLECULAR SIEVES

K.J. CHAO and L.J. LEU Department o f Chemistry, Tsinghua U n i v e r s i t y , Hsinchu, Taiwan

ABSTRACT The i n c o r p o r a t i o n o f S i i n t o AlP04-5 framework m o d i f i e s t h e a c i d i t y and c a t a l y t i c p r o p e r t i e s o f t h e h o s t w i t h o u t d i s r u p t i n g i t s microporous s t r u c t u r e . Bransted a c i d s i t e s w i t h medium s t r e n g t h were generated b y S i s u b s t i t u t i o n , w h i l e o n l y v e r y weak a c i d i t y was found on t h e o r i g i n a l A1P04-5. B o t h A1P04-5 and SAPO-5 were found t o be a c t i v e i n n o n - o x i d a t i v e dehydrogenation o f ethylbenzene t o s t y r e n e ; t h e a c t i v i t y o f e t h y l benzene c r a c k i n g t o benzene depends on t h e S i c o n t e n t o r B r d n s t e d a c i d i t y on SAPO-5.

INTRODUCTION C r y s t a l l i n e aluminophosphate m o l e c u l a r s i e v e s c o n s i s t o f a l t e r n a t i n g alumina and phosphate t e t r a h e d r a and so a r e e l e c t r o v a l e n t l y n e u t r a l w i t h no e x t r a framework c a t i o n s and no ion-exchange c a p a c i t y ( r e f . 1,2). (E.N.=2.2)

The phosphorus atom

o f h i g h e l e c t r o n e g a t i v i t y may produce a s h i f t i n e l e c t r o n d e n s i t y

away from t h e aluminum atom (E.N.=1.6)

r e s u l t i n g i n a d i p o l a r nature o f t h e

Alp04 s u r f a c e . U s i n g t h e s e m i e m p i r i c a l CND0/2 quantum c a l c u l a t i o n on a c l u s t e r model o f Alp04

, M o f f a t e t a l . ( r e f . 3) found t h a t t h e oxygen atoms possess

n e g a t i v e charge and f u n c t i o n as Lewis base s i t e s , phosphorus atoms w i t h h i g h e r p o s i t i v e charge compared w i t h aluminum atoms a c t as Lewis a c i d s i t e s ; and Brdnsted a c i d s i t e s a r e t h e p r o t o n s a t t a c h e d t o t e r m i n a l oxygen atoms on t h e s u r f a c e o f aluminophosphate. Therefore, t h e r e a r e v e r y few B r d n s t e d a c i d s i t e s and t h e m a j o r i t y o f a c i d s i t e s i s Lewis a c i d s i t e s i n Alp04 m o l e c u l a r s i e v e s . The s p e c t r o s c o p i c r e s u l t s ( r e f . 4) show t h a t t h e a c i d s i t e s a r e m o d e r a t e l y s t r o n g and t h e base s i t e s a r e v e r y weak on A1P04-5 m o l e c u l a r s i e v e which has an u n i d i m e n s i o n a l p o r e system c o n s i s t i n g o f c y l i n d r i c a l channels bounded by 12 membered r i n g s ( r e f . 5). The i n c o r p o r a t i o n o f s i l i c o n i n t o t h e aluminophosphate framework leads t o s i l i c o a l u m i n o D h o s p h a t e m o l e c u l a r s i e v e s (SAPO) ( r e f . 6 ) . The s i l i c o n atoms can m a i n l y s u b s t i t u t e i n t o t h e aluminophosphate framework v i a ( 1 ) s i l i c o n s u b s t i t u t i o n f o r phosphorus, ( 2 ) s u b s t i t u t i o n o f two s i l i c o n s f o r one aluminum p l u s one phosphorus. The s i l i c o n s u b s t i t u t i o n f o r phosphorus r e s u l t s i n a n e g a t i v e l y charged framework which can be coupled w i t h exchangeable

20

c a t i o n s and Brdnsted a c i d s i t e s . The amount o f Brdnsted a c i d s i t e s can be increased by s i l i c o n s u b s t i t u t i o n f o r phosphorus i n t h e aluminophosphate framework. I n t h i s paper, we r e p o r t t h a t t h e i n c o r p o r a t i o n o f S i i n t o t h e n e u t r a l A1P04-5 framework m o d i f i e s i t s p h y s i c a l and c a t a l y t i c p r o p e r t i e s w i t h o u t disrupting

its

microporous s t r u c t u r e .

The framework s i t t i n g o f S i was

confirmed by powder XRD, 2 9 S i MASNMR and EPMA ( e l e c t r o n microprobe a n a l y s i s ) . The temperature programmed d e s o r p t i o n (TPD) o f ammonia from ammonia adsorbed o r ammonium exchanged samples was used f o r c h a r a c t e r i z i n g t h e a c i d i t y and i o n exchange c a p a c i t y o f SAPO-5 and AlP04-5.

The few Brfinsted a c i d s i t e s on AlP04-5

were found t o be a c t i v e i n xylene i s o m e r i z a t i o n and cumene c r a c k i n g ( r e f s . 7 - 9 ) . L i t t l e a t t e n t i o n has been p a i d t o t h e importance o f b a s i c s i t e s on phosphates. As a c a t a l y s t having s u i t a b l e acid-base p a i r s i t e s sometimes shows pronounced a c t i v i t y even i f i t s a c i d o r base s t r e n g t h i s v e r y weak i n t h e form o f simple a c i d o r base. I n t h i s work, t h e c a t a l y t i c a c t i v i t i e s o f A1P04-5 and SAPO-5 were t e s t e d on ethylbenzene conversion. Ethylbenzene was found t o be converted t o benzene by a c i d i c c r a c k i n g on Brfinsted a c i d s i t e s and t o s t y r e n e by nono x i d a t i v e dehydrogenation on dual Lewis acid-base s i t e s . EXPERIMENT PreDaration and C h a r a c t e r i z a t i o n The precusors o f AlP04-5 based molecular s i e v e s (AlP04-5, SAPO-5, BAPO-5 and MgAPO-5) were prepared by r e a c t i n g orthophosphoric a c i d (Verck)

,

pseudoboehmite (Verse1 250)/ and c a t i o n source o f Ludox HS-40 (Du P o n t ) , HgBOg, o r MgC12 (Merck) w i t h t r i p r o p y l a m i n e i n t h e hydrothermal c o n d i t i o n o u t l i n e d by Wilson e t a l . ( r e f . 1 ) . The c r y s t a l l i n e phase was i d e n t i f i e d by XRD on a SCINTAG PADV powder d i f f r a c t o m e t e r and examined by scanning e l e c t r o n microscopy w i t h EPMA on a Jeol Superprobe 733 i n s t r u m e n t and b y MASNMR spectroscopy on a Bruker MSL-200 instrument. The elemental compositions o f products were a l s o analyzed by I C P ( i n d u c t i v e l y - c o u p l e d plasma atomic emission spectrometry). M o d i f i c a t i o n o f A1P04-5 and SAPO-5 samples, which had been c a l c i n e d a t 5OO0C, was made by impregnation w i t h aqueous s o l u t i o n o f 2-5 w t % Mg(CHgC00)2 or F.3803 and MgC12 . The NH4 form o f t h e molecular sieves was obtained by five-times-repeated ion-exchange o f t h e s y n t h e t i c samples w i t h 1N NH4C1 s o l u t i o n ; t h e samples were p r e t r e a t e d i n d r y n i t r o g e n and a i r f l o w a t 50OoC. A f t e r c a l c i n a t i o n a t 5OO0C, samples o f A1P04-5 and SAPO-5 were a l s o cooled t o room temperature i n f l o w n i t r o g e n and t r e a t e d w i t h ammonia f l o w a t 100 o r 200OC. Excess ammonia t h e n was swept o u t from t h e sample a t 100 o r 2DD°C by f l o w i n g d r y N2. The a c i d i t y and c a t i o n exchange c a p a c i t y o f molecular s i e v e products were determined by TPD o f

21

o f ammonia from NH4SAPO-5 o r NHqMgAPO-5 and ammonia adsorbed AlP04-5 o r SAPO-5. The evolved ammonia was trapped i n a s o l u t i o n o f b o r i c a c i d and t i t r a t e d b y s u l f a m i c a c i d ( r e f . 1 0 ) . A h e a t i n g r a t e o f 5oC min-1 and a sweep gas f l o w r a t e o f 30 cm3min-1 were used. The number o f m i l l i e q u i v a l e n t o f ammonia evolved p e r gram sample was c a l c u l a t e d from t h e volume o f t i t r a n t used p e r two minut es vs. temperature o r f o r t h e whole range o f d e s o r p t i o n temperature f rom 100 t o 50OoC. C a t a l y t i c R eac t io n The c a t a l y t i c a c t i v i t i e s on ethylbenzene conversion were determined i n a fixe d -b ed m i c r o r e a c t o r system. A sample o f 0.25 g c a t a l y s t and 1.0 g q u a r t z powder was sandwiched w i t h q u a r t z wool i n a s t a i n l e s s s t e e l tube o f 0.7 cm i n n e r diamet e r. A l l experiments were performed a t atmospheric pressure. P r i o r t o t e s t i n g , each sample was heated f r o m room temperature t o 6OO0C (5'C/min) and c a l c i n e d a t 6OO0C f o r 2h i n a n a i r stream, purged by a h e l i u m stream f o r 30 m i n and t h en c o oled t o t h e r e a c t i o n temperature. Ethylbenzene was f e d v i a a h e l i u m stream which was s a t u r a t e d w i t h ethylbenzene vapor by passage t hrough a b u b b l e r . Reactor f e ed stream and e x i s t stream were analyzed b y FID gas chromatography. A 5% SP-1200/1.75% Bentone on 100/120 S u p e l c o p o r t column was used f o r analyses. As t h e vapor p re s s u r e o f t o l u e n e i s h i g h e r t h an t h a t o f ethylbenzene, t h e c o n t e n t o f t o luene i m p u r i t y was found t o be i n creased t o 2.5 mole% o f t h e f eed. RESULTS AND D I S C U S S I O N A1 1 t he c r y s t a l 1 i n e p r o d u c t s have t h e s i m i l a r XRO p a t t e r n and framework s t r u c t u r e as AlP04-5 ( r e f . 5 ) . The amount o f s i l i c o n i n c o r p o r a t i o n i n SAPO-5 i s low, as shown i n t h e c o m p o s i t i o n o f Al:P:Si=1:1:0.04-0.07

by EPMA and I C P .

The s i m i l a r S i c o n t e n t was found i n b o t h c r y s t a l and b u l k SAPO-5 samples. The absence o f a octahedra 27Al MASNMR s i g n a l t o -0 ppm and t h e presence o f o n l y one 31P MASNMR s i g n a l a t -31 ppm show t h a t t h e r e i s no amorphous m a t e r i a l p r e s e n t i n t h e s y n t h e s i z e d SAPO-5 samples. Two s i l i c a species generat ed i n SAPO-5 have been i d e n t i f i e d by *9Si MASNMR as shown i n F i g . 1. The s i g n a l s w i t h chemical s h i f t s o f -92 and -111 ppm a r e p r o b a b l y c h a r a c t e r i s t i c of S i 4 ' s u b s t i t u t i o n f o r P5+ and t h e c l u s t e r o f s i l i c a i n SAPO-5 ( r e f . 11). The d i s s o c i a t i o n o f ammonia f r o m ammonium exchanged m o l e c u l a r sieves has been e s t a b l i s h e d as t h e mechanism f o r g e n e r a t i n g Bransted a c i d s i t e s . The s t r e n g t h o f t h e s i t e s generated i s r e f l e c t e d on t h e ammonia decomposition temperature. The amount ( i n m i l l i e q u i v a l e n t ) and t h e temperature o f ammonia evolved from NH4SAPO-5 a r e i n agreement w i t h t h a t from NH3 adsorbed on SAPO-5 a t 200°C as shown i n F i g . 2a and Table 1. The a c i d values o f NH4' f o r m o f SAPO-5 a r e 0.7 and 0.5 f r a c t i o n s o f t h e t o t a l s i l i c o n c o n t e n t s i n SAPO-5(A) and SAPO(6) r e s p e c t i v e l y , i n which t h e S i c ont e nt s a r e 0.7 w t % of SAPO-5(A) and 1.2 w t % o f SAPO(6) r e s p e c t i v e l y .

22

T h i s i n d i c a t e s t h a t t h e r e l a t i v e c o n t r i b u t i o n o f S i s u b s t i t u t i n g P decreased w i t h i n c r e a s i n g S i c o n t e n t i n samples. AlP04-5 based m o l e c u l a r s i e v e s were a l s o s y n t h e s i z e d i n t h e presence o f H3BO3 o r MgC12. The p r o d u c t s c o n t a i n e d ~ 0 . 1w t % o f B b y I C P o r -1.0 w t % o f

Hg by I C P and EPMA and were termed BAPO-5 o r MgAPO-5. The a n a l y t i c a l r e s u l t s s u p p o r t t h e o c c u r r e n c e o f a r e a s o n a b l e a d d i t i o n o f B o r Mg t o A1P04-5 c o m p o s i t i o n . The TPD p r o f i l e s o f NH3 on AlP04-5, SAPO-5, BAPO-5 and MgAPO-5 a r e g i v e n i n F i g . 2. The AlP04-5 and BAPO-5 c o n t a i n v e r y few s t r o n g a c i d s i t e s , and t h e m a j o r i t y o f s i t e s i s weak. There e x i s t s a abroad s i t e d i s t r i b u t i o n on SAPO-5 which c o n t a i n s weak a c i d s i t e s as A1P04-5 (Td=200°C) and s t r o n g B r d n s t e d a c i d s i t e s (Td=300°C). The s t r e n g t h o f t h e s e a c i d s i t e s on AlP04-5 and SAPO-5 m o l e c u l a r s i e v e s i s weaker t h a n t h a t on z e o l i t e ZSM-5 (Td=400°C) ( r e f . 10). S u b s t i t u t i o n o f boron i n t o aluminophosphate l a t t i c e does n o t appear t o p r o v i d e s t r o n g a c i d s i t e s , w h i l e t h e magnesium s u b s t i t u t i o n f o r aluminum r e s u l t s i n a a n i o n i c framework and s m a l l member o f s t r o n g B r e n s t e d a c i d s i t e s (Td=4J0°C). B u t extraneous o x i d e s and h y d r o x i d e s i n g e n e r a l do n o t enhance B r d n s t e d a c i d i t y . A f t e r h e a t t r e a t m e n t a t 7OO0C, MgAPO-5 showed p a r t i a l s t r u c t u r a l d e g r a d a t i o n as d e t e c t e d b y X-ray powder d i f f r a c t i o n . The thermal s t a b i l i t y o f MgAPO-5 i s t h e r e f o r e l e s s t h a n t h a t o f A1PO4-5 and SAPO-5 whose decomposition t e m p e r a t u r e

I

- 60

-100 -140 ppm vs. TMS

F i g . 1 . 29Si MASNMR spectrum o f SAPO-5(B)

>lOOO°C.

23

10

5

0

5

0 C

2.5

I

0

,---\

Temperature

F i g . 2.

400

200

600

("C)

TPD o f NH3 f r o m m o l e c u l a r s i e v e s ( a ) SAPO-5, ammonia i n i t i a l l y sorbed

a t 100°C (-.-)

o r 2OO0C (----) and NH4SAPO-5 (-);

i n i t i a l l y sorbed a t 100°C (-) NHqMgAPO-5 (-) t i t r a t i o n data.)

(b) A1P04-5, ammonia

or 2OO0C (----); ( c ) NH4BAPO-5 (---) and

(The TPD p r o f i l e s a r e o b t a i n e d by a l e a s t - s q u a r e s f i t t i n g o f

24

TABLE 1 Composition and a c i d i t y o f m o l e c u l a r s i e v e s

S u r f a c e S i :A1 :P b y EPMA B u l k SI% ( w t ) b I C P S u r f a c e S i % (wtf b y EPMA A c i d amount (m mole/g) by TPD o f NH3 adsorbed sample ( ZOOOC) A c i d amount (T mole/g) by TPD o f NH4 exchanged sample

SAPO-5( A)

SAPO-5( B)

A1P04-5

0.04:l.l:l.O

0.07:l.O:l.O 1.2 1.2 0.22

-0:l.O:l.O 0.1

-

0.7 0.17

-

0.03

0.22

Ethylbenzene c o n v e r s i o n The c a t a l y t i c dehydrogenation o f e t h y l b e n z e n e i s o f i n d u s t r i a l i m p o r t a n c e i n t h e manufacture o f s t y r e n e ( r e f s . 1 2 - 1 8 ) .

I n o x i d a t i v e dehydrogenation,

an acid-promoted mechanism was proposed b y s t u d y i n g t h e r e a c t i o n on Na.Si02.Al203 ( r e f . 12) and SnO.P205 ( r e f . 13) c a t a l y s t s . The c a t a l y t i c a c t i v i t y o f o x i d e s on t h e n o n o x i d a t i v e d e h y d r o g e n a t i o n was c o n s i d e r e d t o be r e l a t e d t o e i t h e r t h e semiconductor p r o p e r t i e s o f m e t a l i o n s i n m e t a l o x i d e s such as C r i n Cr203.Al203 ( r e f . 14) and Fe i n FeO ( r e f . 151, o r t h e a c i d base p a i r s i t e s on t h e mixed o x i d e s as Ti02eZr02 ( r e f . 1 6 ) . R e s u l t s from a c o n t i n u o u s - f l o w f i x e d - b e d m i c r o r e a c t o r a r e g i v e n i n Table 2 . N o n - o x i d a t i v e dehydrogenation t o s t y r e n e and d e a l k y l a t i o n t o benzene were t h e main r e a c t i o n s i n t h e c o n v e r s i o n o f e t h y l b e n z e n e on A1P04-5 based m o l e c u l a r s i e v e s a t 5OO0C, w h i l e t h e amorphous aluminophosphates e x h i b i t e d v e r y low a c t i v i t y on b o t h r e a c t i o n s . W i t h styrene:benzene mole r a t i o > 5 , AlP04-5 i s more a c t i v e i n n o n - o x i d a t i v e dehydrogenation t h a n i n d e a l k y l a t i o n . Due t o t h e presence o f B r d n s t e d a c i d s i t e s , t h e y i e l d o f s t y r e n e was suppressed and t h e p r o d u c t i o n o f benzene was enhanced on SAPO-5. However, e t h y l b e n z e n e was f o u n d t o have no s i g n i f i c a n t dehydrogenation on a l u m i n o s i l i c a t e m o l e c u l a r s i e v e ZSM-5; d i s p r o p o r t i o n a t i o n o r d e a l k y l a t i o n p r o d u c t s o f d i e t h y l b e n z e n e , x y l e n e , t o l u e n e and benzene were o b t a i n e d on t h i s a c i d c a t a l y s t a t 320-500°C. A1P04-5 and SAPO-5 c a t a l y s t s were a l s o m o d i f i e d b y i m p r e g n a t i o n w i t h aqueous s o l u t i o n o f Mg(CH3C00)2~rH3B03 and MgC12 r e s p e c t i v e l y . The i n f o r m a t i o n o b t a i n e d i n MgO and B2O3 m o d i f i c a t i o n concerns t h e r o l e s o f t h e a c i d and base c e n t e r s o f c a t a l y s t s i n ethylbenzene c o n v e r s i o n . Table 2 shows t h a t t h e t o t a l c o n v e r s i o n of e t h y l b e v e n e and t h e y i e l d o f s t y r e n e decrease w i t h t h e a d d i t i o n o f HgBOg and change s l i g h t l y b y t r e a t i n g AlP04-5 w i t h Mg(CH$00)2.

This

25

i n d i c a t e s t h a t t h e b a s i c i t y of t h e c a t a l y s t may p l a y an i m p o r t a n t r o l e i n dehydrogenation r e a c t i o n . The i n c o r p o r a t i o n o f boron i n t o A1P04-5 leads t o BAPO-5 which has a c i d i t y and a c t i v i t y s i m i l a r t o A1P04-5. The s u b s t i t u t i o n magnesium f o r a aluminum i n MgAPO-5 p r o v i d e s s t r o n g Brdnsted a c i d s i t e s and gives h i g h preference f o r benzene p r o d u c t i o n on ethylbenzene conversion. When the Brdnsted protons a r e p a r t i a l l y exchanged by magnesium c a t i o n s , t h e a c t i v i t y o f d e a l k y l a t i o n i s reduced and t h e s e l e c t i v i t y o f dehydrogenation i s s l i g h t l y increased on SAPO-5 (5,Mg).

The i n c o r p o r a t i o n o f S i and Mg i n aluminophosphate

framework leads t o an increase i n t h e t o t a l number o f Brdnsted a c i d s i t e s , w h i l e Lewis a c i d and base s i t e s , which a r e most l i k e l y l o c a t e d on P and 0 atoms r e s p e c t i v e l y , a r e o n l y s l i g h t l y changed. As t h e y i e l d o f s t y r e n e was n o t increased by i n c o r p o r a t i n g S i o r Mg i n A1P04-5,

t h e Brbnsted a c i d s i t e s seem

n o t t o p a r t i c i p a t e i n dehydrogenation r e a c t i o n .

TABLE 2 A c t i v i t i e s o f molecular sieves i n ethylbenzene conversion.a Catalystb A1 Po4-5 A1P04-5 (5,Mg) A1P04-5 (2,B) A1P04-5 (5,B) SAPO-5 ( A ) SAPO-5 SAP@-5 (5,Mg) BAPO-5 MgAPO-5 ZSM-5 (5,Mg) ZSM-5 (5,Mg)'

Ethylbenzene conv. % 5.8 6.1 3.5 0.3 7.5 12.9 6.3 7.3 26.2 91.5 31.2

Benzene 1 .o 0.5 0.9 0.3 2.6 10.8 3.1 1.7 23.1 94.7 22.9

Product d i s t r i b u t i o n ( % b y mole) E thy1 S t rene Toluene benzene Styrene

-

2.0 2.1 1.9 2.5 2.4 1.9 1.6 1.9 2.3 2.2 4.8

91.7 91.4 94.0 97.2 90.5 84.6 91.2 90.2 71.7 1.6 66.3

&

5.3 6.0 3.2 0.1 4.5 2.6 4.0 6.2 2.9 (1 . 5 I e (6.1)

5.4 11 3.5 0.4 1.7 0.3 1.3 3.7 0.1

-

aReaction temperature=500°C, atmospheric pressure; WHSV=O.Ol , time on stream=lhr, feed=97.5 mole% ethylbenzene and 2.5 mole% toluene. b w i t h 5 Wt9: Mg(CH3C00)2 and 2 o r 5 w t % H3BO-j impregnated A1P04-5 samples were denoted as AlP04-5 (5,Mg) and AlP04-5 ( 2 , B ) o r AlP04-5 (5,B); w i t h 5 w t % MgC12 impregnated SAPO-5 and ZSM-5 were denoted as SAPO-5 (5,Mg) and ZSM-5 (5,Mg). The Bransted a c i d values o f SAPO-5, SAPO-5 (A) and SAPO-5 (5,Mg) a r e 0.21, 0.17 and 0.15 m mole/g, r e s p e c t i v e l y . C320OC. dXy1 ene . eDiethylbenzene. The non-oxidative dehydrogenation over CrO3 c a t a l y s t i s based on t h e chemisorption o f hydrogen on surface oxygen w i t h a cleavaqe o f t h e C-H bond and the a l k y l group bounded t o a C r atom ( r e f . 1 4 ) . I n t h e p r e s e n t work,

26

c r y s t a l l i n e microporous A1P04-5 was found t o be a c t i v e i n ethylbenzene dehydrogenation i n the absence o f oxygen. The r e s u l t s o f H3803 doping i n d i c a t e t h a t t h e weak base s i t e s o f t h e c a t a l y s t may p l a y an i m p o r t a n t r o l e i n dehydrogenation. However, t h e b a s i c i t y l o c a t e d on oxygen atoms i s n o t s t r o n g enough, and t h e c o o p e r a t i o n w i t h a d j a c e n t a c i d i c s i t e s i s e s s e n t i a l t o c a t a l y z e t h e r e a c t i o n . A concerted H2 e l i m i n a t i o n mechanism was proposed t o proceed on A1P04-5 and SAPO-5. I n which, two hydrogens o f a- and B- carbons o f ethylbenzene simultaneously a t t a c k t h e a c i d and base s i t e s o f t h e c a t a l y s t . The average bond d i s t a n c e o f P-0 (1.52 A) i s very c l o s e t o t h e C-C bond d i s t a n c e and s h o r t e r than t h e A1-0 (1.72 A) d i s t a n c e ( r e f . 5 ) , and t h i s may p r o v i d e a proper environment f o r acid-base c a t a l y z e d r e a c t i o n . However, t h e Lewis a c i d and base s i t e p a i r s a r e n o t s t r o n g as few Brdnsted a c i d s i t e s on AlP04-5. The y i e l d o f s t y r e n e was n o t increased by r a i s i n g t h e r e a c t i o n temperature above 5OO0C, a t t h i s temperature r e g i o n where Brdnsted a c i d c r a c k i n g became s i g n i f i c a n t . As SAPO-5 and MgAPO-5 e x h i b i t b o t h Brdnsted a c i d s i t e s and Lewis acid-base s i t e s , the adsorbed ethylbenzene on p r o t o n i c species may b l o c k t h e f o r m a t i o n o f dehydrogenation i n t e r m e d i a t e s and i n t u r n reduce the y i e l d o f styrene. CONCLUSION The present r e s u l t s show t h e importance o f b o t h t h e a c i d i t y and b a s i c i t y o f AlPO4 and SAP0 molecular sieves on c a t a l y t i c r e a c t i o n s . I n t r o d u c t i o n o f b i v a l e n t ( i .e. Mg) and t e t r a v a l e n t ( i .e. S i ) c a t i o n s i n t o t h e aluminophosphate framework r e s u l t s i n t h e f o r m a t i o n o f Brdnsted a c i d s i t e s and enhances the acidic catalytic a c t i v i t y .

REFERENCES 1 S.T. Wilson, B.M. Lok, C.A. Messina, T.R. Cannan and E.M. Flanigen, J . Am. Chem. SOC. 104(1982) 1146-1147. 2 E.M. Flanigen, B.M. Lok, L. P a t t o n and S.T. Wilson, i n Y . Murakami ( E d i t o r 1 Proc. 7 t h I n t . Z e o l i t e Congress, Toyko, 1986, E l s e v i e r , Amsterdam, 1986, pp. 103-112. 3 J.8. M o f f a t , R . V e t r i v a l and B. Viswanathan, J . Mol. C a t a l . 30(1985) 171180. 4 G. Dworezkov, G. Rumplmayer, H. Mayer and J.A. Lercher, i n M. Che ( E d i t o r ) , Adsorption and C a t a l y s i s on Oxide Surfaces, E l s e v i e r , Amsterdam. 1985, op. 163-171. 5 S.T. Wilson, B.M. Lok, C.A. Messina, T.R. Cannan and E.M. Flanigen, Adv. Chem. Ser. 218(1983) 79-119. 6 B.M. Lok, C.A. Messina, R . L . Patton, R.T. Gajak, T.R. Cannan and E.M. Flanigen, J . Am. Chem. SOC. 106(1984) 6092-6093. 7 V.R. Choudhary and D.B. Akolekar, J . C a t a l . 103(1987) 115-125. 8 D . R . Pyke, P. Whitney and H. Houghton. Appl. C a t a l . 18(1985) 173-182. 9 S.G. Hedge, R. Ratnasamy, L.M. Kustov and B.B. Kazansky, Z e o l i t e s B(1988) 137-141. 10 K.J. Chao, B.H. Chiou, C.C. Cho and S . Y . Jeng, Z e o l i t e s 4(1984) 2-4.

21

11 I . P . Appleyard, R.K. H a r r i s and F.R. F i t c h , Chem. L e t t . (1985) 1747-1750. 12 T . Tagawa, T. H a t t o r i and Y . Murakami, J. C a t a l . 75(1982) 56-77. 13 Y . Murakami, K. Iwayama, H. Uckida, T. H a t t o r i and T. Tagewa, J. C a t a l . 71(1981) 257-269. 14 S . Carra and L. F o r n i , C a t a l . Rev. 5(1972) 159-185. 15 E.H. Lee, Catal. Rev. 8(19731 285-300. 16 I . Wang, W.F. Chang, R.J. Shiau, J.C. Wu and C.S. Chung, J. C a t a l . 83(1933) 428-435. 17 T. Yashima, K . Sato, T. Hayasaka and N . Hara, J . C a t a l . 26(1972) 303-310. 18 Monsanto Co., US Patent, 4,115,424(1978).



ON THE NATURE OF THE CATALYTIC ACTIVITY OF SAPO-5

CH.MINCHEV1, V.KANAZIREV1, V . H A V R O D I N O V A 1 ,

V.PENCHEV1 a n d H. LECHERT2

t l n s t i t u t e o f O r g a n i c C h e m i s t r y , S o f i a 1040

Bulgaria)

2 1 n s t i t u t e o f P h y s i c a l C h e m i s t r y , Hamburg Un v e r s i t y , 2 Hamburg

3 (FRG)

ABSTRACT An a t t e m p t t o e s t i m a t e t h e n a t u r e o f t h e c a t a l y t i c a c t i v i t y o f SAPO-5 was made by means o f t h e " i n n e r s t a n d a r d " a p p r o a c h . SAPO-5 m a t e r i a l s were compared w i t h model m i x t u r e s o f HY i n t r o d u c e d i n t o a n AIPO-5 m a t r i x as w e l l as w i t h HZSM-5 and h i g h l y d e a l u m i n a t e d HY. The s e l e c t i v i t y p a t t e r n s i n m-xylene c o n v e r s i o n s u p p o r t t h e a s s u m p t i o n o f a r e l a t i v e l y homogeneous S i - i n c o r p o r a t i o n , The g e n e r a t e d a c t i v e c e n t e r s a r e s i t u a t e d f a r f r o m each o t h e r as i n t h e c a s e o f t h e h i g h l y d e a l u m i n a t e d f a u J a s i t e .

I NTRODUCTI ON

The new g e n e r a t i o n o f a l u m i n o p h o s p h a t e - b a s e d m i c r o p o r o u s o x i d e s ( A I P 0 4 - n , SAPO-n,

etc.)

( r e f . 1 ) r e v e a l s new p o s s i b i l i t i e s o f c a t a l y s i s by m o l e c u l a r

s i e v e s . The i n c o r p o r a t i o n o f S i i n t h e n o n - a c i d i c a l u m i n o - p h o s p h a t e framework e l i c i t s i n many cases a s i g n i f i c a n t c a r b o n i o g e n i c c a t a l y t i c a c t i v i t y . Recently, remarkable

c a t a l y t i c a c t i v i t y o f SAPO-5 i n n - b u t a n e ( r e f . 2)

and cumene ( r e f . 3) c r a c k i n g , o - x y l e n e

isomerization (ref.3),

alkylation

o f t o l u e n e w i t h methanol ( r e f . 4 ) , o l i g o m e r i z a t i o n o f p r o p e n e ( r e f . 4 ) , c o n v e r s i o n o f decane ( r e f . 5) a n d methanol ( r e f . 6) was r e p o r t e d .

The

c a t a l y t i c a c t i v i t y o f t h e aluminophosphate-type m a t e r i a l s ranges w i t h i n a l m o s t two o r d e r s o f m a g n i t u d e a c c o r d i n g t o t h e c o m p o s i t i o n and p r e p a r a t i o n c o n d i t i o n s ( r e f . 2 ) . Adsorption and I R data

suggest t h e e x i s t e n c e o f

a c i d i c c e n t e r s i n t h e SAPO-5 s t r u c t u r e ( r e f . 3, 5

-

7).

The n a t u r e o f t h e c a t a l y t i c a c t i v i t y o f t h e SAPO-5 m a t e r i a l s i s s t i l l n o t f u l l y understood ( r e f . 7 ) .

O b v i o u s l y , t h e mechanism o f S i i n c o r p o r a t i o n

i n t o t h e l a t t i c e i s o f g r e a t i m p o r t a n c e f o r t h e appearance o f c a t a l y t i c a l l y a c t i v e c e n t e r s . A t t e m p t s were made t o a p p l y some c u r r e n t c o n c e p t s i n t h e

z e o l i t e c a t a l y s i s t o t h e s e new o b j e c t s ( r e f . 7 ) . The g e n e r a t i o n o f non-comp e n s a t e d charges i n t h e a l u m i n o - p h o s p h a t e framework a n d t h e p o s s i b l e c o n t r o l o f t h i s p r o c e s s a r e t h e most i m p o r t a n t d i s c u s s i o n t o p i c s i n t h e r e c e n t l i t e r a t u r e ( r e f . 5-8). I n t h e p r e s e n t work, a n " i n n e r s t a n d a r d " a p p r o a c h has been a p p l i e d f o r

30 e s t i m a t i o n o f t h e p r o p e r t i e s o f SAPO-5 as a c i d c a t a l y s t . The HY z e o l i t e , m e c h a n i c a l l y d i s p e r s e d i n a m a t r i x o f AIP04-5, s t a n d a r d . The physico-chemical

was used as an i n n e r

and c a t a l y t i c p r o p e r t i e s o f t h e so p r e p a r e d

model samples were compared t o those o f SAPO-5, as w e l l as t o ZSH-5 and dealuminated HY w i t h low d e n s l t y o f t h e a c i d c e n t e r s .

EXPERIMENT Samples and c h a r a c t e r i z a t i o n SAPO-5 and A1P04-5 were s y n t h e s i z e d a c c o r d i n g t o ( r e f . 9,lO)

by

u s i n g Pr3N (Herck) and a g e l whose c o m p o s i t i o n i s p r e s e n t e d i n T a b l e 1.

TABLE 1 Composition o f t h e r e a c t i o n m i x t u r e , mol Sample AP SPI SPII

Type AIPO-5 SAPO-5 SAPO-5

Pr3N 1.5 2.0 2.0

Si02

A1203

p2°5

H20

1 .O 1 .o 1 .o

1 .o 1 .o 1 .o

40 50 50

0.4 0.9

Pseudoboehmite f r o m Condea, 85% o r t h o p h o s p h o r i c a c i d and amorphous s i l i c a (Herck) were used as sources f o r Al2O3, P2O5 and SiO2 r e s p e c t i v e l y . The c r y s t a l l i z a t i o n was c a r r i e d o u t under 423-453K

i n T e f l o n tubes i n an a u t o -

c l a v e f o r 6 t o 24 hours. The f i n a l thermal t r e a t m e n t was performed i n a i r a t 823-873K

f o r 6 hours i n a m u f f l e oven.

The samples used f o r comparison were:

HY(Si02/A1203-5.1)

and HZSM-5

(Si02/A1203 -200) o b t a i n e d by t h e u s u a l d e c o m p o s i t i o n o f t h e NHq+-form (ref.lO,as

w e l l as a dealuminated HY, d e s i g n a t e d as US-Ex

prepared a c c o r d i n g t o ( r e f . 1 2 ) . 0.9AP-O.1HY

(Si02/A1203=200)

The model samples 0.95AP-0.05HY

and

were p r e p a r e d by thorough m i x i n g o f t h e A1P04-5 m a t e r i a l w i t h

5 and 10 w t % o f t h e inner s t a n d a r d HY, The p h i s i c o - c h e m i c a l

characteri-

z a t i o n o f t h e samples was made by t h e f o l l o w i n g t e c h n i q u e s : X-ray powder diffraction,CuKkby

a DRON a p p a r a t u s , I R spectroscopy

in the region o f

1400-400 cm-l u s i n g KBr d i s k s , by a Specord 75 I R s p e c t r o p h o t o m e t e r , e l e c t r o n microscopy by JSH-200 and simultaneous t h e r m a l a n a l y s i s (TG-DTA- DTG) up t o 1 2 7 3 ~w~i t h 100/min i n a i r i n MOM a p p a r a t u s . A d s o r p t i o n and c a t a l y t i c measurements The adsorption-thermodesorption measurements were c a r r i e d o u t i n f l o w a t e l e v a t e d temperature.

The a d s o r p t i o n o f NH3(30 kPa,

i n a He s t r e a m a t 423K

and TPD up t o 87310 was measured a 8 a l r e a d y descr i b e d ( r e f . 13). The a d s o r p t i o n and c a t a l y t i c experiments w i t h m-xylene were p e r f o r m e d i n one and t h e same f l o w - t y p e a p p a r a t u s c o u p l e d "on l i n e n w i t h a GC. The c a t a l y s t ' s w e i g h t was 0.49.

The m-xylene was i n t r o d u c e d b y means

31 o f a s a t u r a t o r . H i g h - p u r i t y N2 was used as a c a r r i e r gas. The p r e l i m i n a r y t r e a t m e n t o f t h e c a t a l y s t s was c a r r i e d o u t f o r 5 h o u r s

i n n i t r o g e n a t 773K, f o l l o w e d b y e s t a b l i s h i n g t h e temperature a t 453K and then i n t r o d u c i n g m-xylene from t h e s a t u r a t o r . The a d s o r p t i o n was t r a c e d by t h e f r o n t a l method and chromatographical m o n i t o r i n g o f t h e m-xylene concentration a t the reactor outlet.

The c a t a l y t i c experiments f o r t h e m-xylene

c o n v e r s i o n were performed immediately a f t e r t h e a d s o r p t i o n as f o l l o w s : r a i s i n g up t h e temperature t o 673K; p a s s i n g t h e r e a g e n t t h r o u g h t h e c a t a l y s t u n t i l c o n s t a n t a c t i v i t y was reached and v a r y i n g t h e c o n t a c t t i m e i n t h e range 0 . 3

-

42h by changing t h e f l o w r a t e o f t h e c a r r i e r gas. The a n a l y -

s i s o f t h e r e a g e n t m i x t u r e and t h e r e a c t o r e f f l u e n t was accomplished by GC. The t o l u e n e d i s p r o p o r t i o n a t i o n was c a r r i e d o u t i n a c o n t i n u o u s f l o w reactor (ref.

14) a t 723 and 753K. The WHSV was l . I h - l ,

Ptoluene=27.5kPa and t h e

Hg/toluene molar ratio.2.5.

RESULTS Physico-chemical c h a r a c t e r i z a t i o n o f t h e i n i t i a l and model samples I n accordance w i t h t h e l i t e r a t u r e , t h e r e s u l t s Obtained show t h a t t h e phase p u r i t y o f AIP04-5

( r e f . 1,6) and SAPO-5 ( r e f . 5 )

‘1

is

s t r o n g l y dependent on t h e c o n d i -

t i o n s o f p r e p a r a t i o n . Combined thermal a n a l y s i s proved t o be Very u s e f u l i n p u r i t y c o n t r o l ( r e f . 15), t o g e t h e r w i t h X-ray scopy.

and I R s p e c t r o -

I n F i g . 1 t h e DTG curves o f

*‘pure** AIPO-5 and SAPO-5,

as w e l l

as those o f samples w i t h i n c r e a s i n g amounts o f phase i m p u r i t y ( c u r v e s

I 373. . 573. . .773 . .973 . .1173 I TEMPERATUK,K

b-d)

a r e presented.

les

were p r e p a r e d u s i n g t h e same

nlmpuren samp-

s t a r t i n g g e l by d i f f e r e n t d u r a t i o n s o f c r y s t a l l i z a t i o n ( c u r v e s b-c)

or

b y a d i f f e r e n t way o f homogenizing

Fig.l.

DTG o f as-synthesized:

a,AIPO-5;

b,c,d,

AlPO-5 w i t h i m p u r i t y ; ,

e,

o f t h e r e a c t i o n mixture (curve d ) .

SAPO-5. They were s u b j e c t e d t o thermal ana-

l y s i s a f t e r d r y i n g a t 333K and r e h y d r a t a t i o n . The minimum o f t h e DTG curves a t 453K a r e an i n d i c a t i o n o f t h e presence o f an u n i d e n t i f i e d s e p a r a t e phase which i s n o t s t a b l e a t 823K. I t i s t o be p o i n t e d o u t t h a t X-ray and I R spectroscopy,

which a r e t h e

32 usual c o n t r o l techniques,

are ineffective for establishing

c e n t r a t i o n s such as t h a t

p r e s e n t i n t h e sample c o r r e s p o n d i n g t o c u r v e b,

Fig.l.Taking

i m p u r i t y con-

i n t o c o n s i d e r a t i o n t h a t t h e p r e p a r a t i o n o f monophase a l u m i n i u m

o r t h o p h o s p h a t e s i s q u i t e d i f f i c u l t a n d c a n be a c h i e v e d by a v e r y p r e c i s e m a i n t e n a n c e o f t h e r e s p e c t i v e optimum c o n d i t i o n s f o r each p r o d u c t ( r e f . we recommend a d d i t i o n a l c o n t r o l by t h e r m a l a n a l y s i s ( r e f .

161,

15).

The p u r i t y o f samples c o n t a i n i n g h i g h e r amounts o f u n d e s i r e d p r o d u c t (Fig.l,

c u r v e s c,d)

may be c h e c k e d by I R s p e c t r o s c o p y ( F i g . 2 ) .

The in-

crease o f t h e i m p u r i t y y i e l d can be c l e a r l y i n d e n t i f i e d i n t h e r e g i o n 950-400 a n d 1200-1050 cm-l. The d i f f e r e n c e between t h e I R s p e c t r u m o f t h e p u r e AIP04-5 a n d SAPO-5 i n t h i s range i s n e g l i g i b l e . The complex p h y s i c o - c h e m i c a l c h a r a c t e r i z a t i o n showed t h a t p r a c t i c a l l y p h a s e - p u r e AIPO-5 a n d SAPO-5 w e r e s y n t h e s i z e d , whose d i f f r a c t i o n p a t t e r n s a r e i n v e r y good agreement w i t h t h e l i t e r a t u r e data ( r e f . 9,lO). The s c a n n i n g e l e c t r o n m i c r o g r a p h s c o n f i r m t h e good c r y s t a l l i n i t y o f t h e m a t e r i a l s used i n t h e a d s o r p t i o n and c a t a l y t i c experiments.

The c r y s -

t a s have a h e x a g o n a l c r o s s - s e c t i o n

1200 Fig.2.

800

O f

1

W A V E N U ~ R cm-1 .

The same methods w e r e a p p l i e d

I R spectrum o f as-synthesized:

a, AIPO-5;

c,d,

a b o u t 10-22y.m.

AIPO-5 w i t h i m p u r i t y ;

e, SAPO-5;

in

he c o m p a r a t i v e s t u d y o f t h e mo-

de I samples 0 . 9 5 AP-0.05HY 0 . 9 AP-O.1HY.

and

The X-ray a n d I R spec-

t r o s c o p y d a t a show t h a t c l e a r i n d i c a t i o n s f o r t h e presence o f a z e o l i t i c m a t e r i a l (HY i n t h i s case) c a n be d i s t n g u i s h e d when i t s c o n c e n t r a t i o n i n t h e AIP04-5

i s about 5wt% (Fig.3)

o r h gher (Fig.4)

I

TPD o f NH3 a n d m - x y l e n e a d s o r p t i o n A r e l a t i v e l y w i d e t e m p e r a t u r e r a n g e o f NH3 d e s o r p t i o n , F i g . 5 ,

i s character-

i s t i c f o r a l l samples. The f o l l o w i n g r e g u l a r i t i e s c a n be o b s e r v e d f r o m t h e data presented: -The c o n c e n t r a t i o n o f t h e c e n t e r s r e a c t i n g w i t h ammonia i s h i g h e s t i n HY.

The model m i x t u r e s 0 . 9 5 AP-0.05HY

and 0 . 9 AP-O.1HY

d e s o r b ammonia i n

33

Fig.3.

o f c a l c i n e d AIPO-5 AIPO-5

1OOo 600 WAVENUM)ER , crn"

X-ray d i f f r a c t i o n p a t t e r n

-

0.05HY

( a ) , and 0 . 9 5 F i g . 4 I R spectrum o f c a l c i n e d

(b); t h e arrows

0 . 9 AIPO-5

n o t e l i n e s c h a r a c t e r i s t i c o f HY.

-

AIPO-5-0.05HY

HY(0.4 g SPll

O.1HY

( a ) , 0.95

( b ) , AIPO-5

(C).

1---I

.-

IHZSM-5

SP I

a- SPII

0

F i g . 5 . TPD chromatograms o f NH3 HY(O.4g)-pure

HY;

HY(0.04g)-HY

d i l u t e d w i t h i n e r t rnater i a l .

F i g . 6 . C o n v e r s i o n o f m-xylene as a f u n c t i o n o f t h e m o d i f i e d c o n t a c t time.

34 t h e same temperature range b u t i t s quant t y i s much s m a l l e r compared t o t h e 'non-di l u t e d " HY. -SPI,

0.95 AP-0.05HY and 0 , 9 AP-O.1HY

have v e r y s i m i l a r TPD c u r v e s . The

TPD maximum of' t h e above-mentioned mater a l s i s s h i f t e d t o lower temperatur e s , w h i l e t h a t o f S P I I i s s h i f t e d t o h i g h e r ones, -The TPD chromatograms o f HZSM-5 and US-Ex used f o r comparison

are typi-

c a l f o r z e o l i t e s o f t h i s k i n d . They i n d i c a t e a h i g h e r r e l a t i v e c o n t r i b u t i o n o f t h e s t r o n g a c i d c e n t e r s . T h e number o f t h e s i t e s i n t e r a c t i n g w i t h NH3 i s

v e r y low because o f t h e h i g h S i / A l

o f t h e s e samples.

Comparison o f t h e q u a n t i t i e s o f NH3 desorbed ( T a b l e 2) f o r AIP04-5 and SAPO-5 shows,

i n agreement w i t h ( r e f . 1,3,6 and 71, t h a t t h e former have

lower a c i d i t y . The s h i f t o f t h e maximum r a t e o f ammonia d e s o r p t i o n t o h i g h e r temperatures f o r S P I I compared t o t h e o t h e r aluminophosphate samples i n d i cates a s p e c i f i c e f f e c t o f t h e increased TABLE 2

S i c o n t e n t on t h e a c i d i t y , The d a t a f o r

Thermodesorption o f ammonia,

t h e mixed samples r e v e a l t h e s i g n i f i -

adsor bed a t 420K, P~%=30kPa

c a n t r o l e o f t h e aluminophosphate m a t r i x , which o b v i o u s l y has a c o n s i d e r -

Samples

mmol NH3/g

a b l e number o f c e n t e r s i n t e r a c t i n g w i t h ammonia ( r e f .

17).

AP

0.12

HY

0.96

The m-xylene a d s o r p t i o n r e s u l t s

0.95AP-0.05HY

0.14

recorded i n t h e p r e - c a t a l y t i c region

0.9AP-0. 1OHY

0.16

showed t h a t HY adsorbed 0 . 8 6 mmol/g

SP I

0.22

m-xylene, w h i l e a d s o r p t i o n values f o r

SPI I

0.24

a l l o t h e r samples amounted t o 0 . 0 3 -

HZSM-5

0.08

0 . 1 6 mmol/g.

US-E x

0.04

The above r e s u l t s i n d i -

cate t h a t the differences i n the acide centers'

samples under e x a m i n a t i o n m a n i f e s t themselves i n a

concentration i n the l i k e manner w i t h

r e s p e c t t o t h e model m-xylene substance, which i s used f o r t h e c a t a l y t i c characterization. C a t a l y t i c studies M-xylene c o n v e r s i o n was s t u d i e d a t 673K. The f l o w r a t e o f t h e m-xylene and t h e w e i g h t o f t h e c a t a l y s t s were v a r i e d i n o r d e r t o o b t a i n c l o s e values f o r t h e o v e r a l l r a t e o f c o n v e r s i o n a t d i f f e r e n t c o n t a c t t i m e s . Under t h e e x p e r i m e n t a l c o n d i t i o n s used,

b o t h i s o m e r i z a t i o n and d i s p r o p o r t i o n a t i o n o f

t h e m-xylene proceed. Table 3 r e v e a l s t h e c o n s i d e r a b l e d i f f e r e n c e s i n t h e c a t a l y t i c a c t i v i t y o f t h e samples.Contact t i m e s d i f f e r i n g by about one o r d e r

o f magnitude a r e necessary t o o b t a i n c l o s e degrees o f c o n v e r s i o n u s i n g HY

35 TABLE 3

Conversion o f m-xylene, T ~ 6 7 3 K

Samples

Contact time, h

Total r a t e o f convers ion, %

Products o f i somer i z a t ion, X

41.5

10.0

7.7

0.30

0.95AP0.05HY

0.3 0.4 0.5

25.6 28.1 37.7

12.1 13.9 17.3

0.95 1.01 1-10

0.9APO.1OHY

0.6 0.7 1. O

34.4 37.5 48.5

19.5 20.8 23.6

0.72 0.80 0.97

0.02gHY

0.3 0.4 1 .o

23.9 28.1 44.3

11.8 13.9 19.3

0.96 1.01 1.32

0.40gHY

5.9

63.7

29.5

1.13

5.9

7.0

37.2 43.9

30.6 34.7

0.21 0.26

SP I w

5.9

42.4

37.3

0.14

US-Ex

10.4 19.8 41.5

24.6 40.2 48.0

20.2 29.4 30.2

0.20 0.36 0.59

5.9 10.4

37.7 43.2

37.4 41.9

0.01 0.03

APW

SPI Iw

HZSM-5

S=

Disprop. , % Isom. , X

wThese samples showed a tendency towards d e a c t i v a t i o n

on one s i d e , and S P I , S P I I and US-Ex on t h e o t h e r . T h i s

i s i n good agreement

w i t h t h e above-established differences i n the adsorption center density o f t h e samples. The AP sample e x h i b i t s v e r y low a c t i v i t y . T h e degree o f convers i o n o b t a i n e d even f o r 42h c o n t a c t t i m e i s o n l y 1O.OX.The a c t i v i t y o f t h e m i x t u r e s 0 . 9 5 AP-0.05HY

and 0 . 9 AP-O.1HY

i s m a i n l y due t o t h e HY component.

B y v a r y i n g t h e c o n t a c t times necessary t o o b t a i n c l o s e degrees o f conver-

s i o n , t h e f o l l o w i n g range o f a c t i v i t y i s observed: Alp04

206

pyridine is highest (10 %, 425 "C) when Cs-zeolite is used. The above examples indicate how it is possible to suppress or to induce consecutive reactions during the alkylation of pyridine merely by means of the appropriate choice of dopant in the zeolite catalyst. The examples also show how the selectivity can be influenced by the type of zeolite employed. In contrast to the side-chain alkylation of toluene using alkali-earth-doped faujasites, it is characteristic of the side-chain alkylation of picolines that alkylation of the nucleus also occurs (e. g. ref. 4). Alkylation of aromatic amines The alkylation of aromatic amines includes the reaction of aniline with methanol (refs. 84, 85) or with olefins (refs. 86 - 88) in the presence of zeolitic and nonzeolitic molecular sieves. In principle, reaction can take place at the N-containing groups forming N-alkylated compounds or at the nucleus forming C-alkylated compounds. In other words, the methylation of aniline, for example, yields toluidine, N- methylaniline and N,N-dimethylaniline. All are useful intermediates for dyestuffs, agrochemicals and drugs as well as for the organic synthesis. A mixture of aniline and methanol in a molar ratio 1:3 reacts at 350 "C and WHSV = 0.8 hr-' with 51.4 % selectivity for N-methylaniline and 20.1 % for toluidine using HZSM-5 with Si02/A1,03 = 60. The conversion is 70 %. That means the acid HZSM-5 already favours N-alkylation over C-alkylation. By impregnating or moulding with, e. g. MgO, thereby reducing the acidity, the amount of Nalkylate can be increased; N-methylaniline was formed with 86.5 % selectivity at 85.5 % conversion. However, only 3,5 % toluidine selectivity was obtained. The alkylation of aniline with olefines such as propylene can be carried out employing H-mordenite (ref. 86), dealuminated mordenite or Y-zeolite (ref. 87) or SAPO 37 (ref. 88). In contrast to the alkylation with methanol, in all these cases C-alkylation is favoured especially in the ortho-position. Using Hmordenite, aniline and propylene in a 1:l molar ratio are converted at 250 C' and LHSV = 0.35 hr-' to o-alkylate with 84 %, p-alkylate with 4 % and N-alkylate with 15 % selectivity. 32 % conversion is obtained. Using dealuminated mordenite the conversion rate can be increased to 76 % whilst maintaining a similar product distribution, and using SAPO 37 a further increase up to 93 % is possible. In the latter case, however, only 64 % o-alkylate selectivity and 12 % p-alkylate selectivity are achieved. The selectivity for N-alkylate is 21 %. In the author's opinion a concerted reaction between aromatic amine and olefine (ref. 86) is responsible for ortho-alkylation being favoured over para-alkylation.As far as the thermodynamics are concerned the para-alkylates are the most stable, as is demonstrated by the fact that their selectivity increases with higher temperatures demonstrates.

207

CONCLUSION This presentation is intended to underline once again the versatility of zeolites for both synthesis and reactions of N-containing compounds. Some examples demonstrate that existing processes can be improved merely by replacing the conventional heterogeneous catalyst. Other examples show the advantages of the change from homogeneously catalysed processes to heterogeneous catalysis if environmental and process engineering problems occur in the separation and work-up. However, in other cases, like the Beckmann rearrangement to produce caprolactam, the results obtained by homogeneous catalysts can not be achieved by zeolitic or non-zeolitic molecular sieves up to now. Considerable effort is still necessary in order to solve this problem. The principles derived from reactions of hydrocarbons on zeolites can generally be applied to the reactions of N-containing compounds. However, there can be a few differences, too, as the alkylation of pyridine or aniline in comparison t o the alkylation of benzene or toluene has shown. Nevertheless, there are some promising results in the chemistry of N-containing organic compounds which encourage us to proceed further along the road of shape-selective catalysis. REFERENCES 1 2 3 4

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Y. Ono, A. H a l g e r i , M. Kaneko, K. Hatada, ACS Symp. Ser. 40 (1977) 596 605 K. Hatada, M. Shimada, K. F u j i t a , Y. Ono, T. K e i i , Chem. L e t t . 1974, 439 K. Hatada, M. Shimada, Y. Ono and T. K e i i , J. Catal. 37 (1975) 166 G. T. K e r r , Ch. J. Plank and E. J. R o s i n s k i , US 3.442.795 (May 06, 19691, M o b i l O i l Corp. Ch. J. Plank, E. J. R o s i n s k i and G. T. K e r r , US 4.011.278 (March 08, 1977), M o b i l O i l Corp. W. F. H o e l d e r i c h and M. Schwarzmann, EP 267.438 (May 18, 1988) BASF AG G. Perego, G. B e l l u s s i , C. Corno, M. Taramasso, F. Buonomo and A. Espos i t o , Stud. Surf. Sci. Catal. 28 (1986) 129 - 136 B. N o t a r i , Stud. Surf. Sci. Catal. 37 (1988) 413 - 425 P. R o f f i a , M. Padovan, E. M o r e t t i and G. De A l b e r t i , EP 208.311 (Jan. 14, 19871, Montedipe S. p. A. F. J. Van d e r Gaag, F. L o u t e r and H. Van Bekkum, Stud. Surf. Sci. Catal. 28 ( 1986) 763 - 769 F. J. Van d e r Gaag, F. L o u t e r , J. Oudejans and H. Van Bekkum, Appl. Catal. 26 (1986) 191 - 201 G. 0. Chivadze, Kh. J. A r e s h i d z e and Ts. J. N a s k i d a s h v i l i , Geterog. K a t a l . 5 (1983) 141 - 146 J. C. Oudejans, F. J. Van d e r Gaag and H. Van Bekkum, i n D. Olson and A. B i s i o ( E d i t o r s ) , Proc. 6 t h I n t . Z e o l i t e Conf., Reno, USA, J u l y 1983, B u t t e r w o r t h G u i l d f o r d , UK, 1984, pp. 536 - 544 S. S. Shepelev and K. G. I o n e , SU 1.321.722 ( J u l y 07, 1987). I n s t . Catal, Novosibirsk M. L. O c c e l l i , I. T. Hsu and L. G. Galya, J. Mol. Catal. 32 (1985) 377 390 Y. Ben T a a r i t , Y. Diab, B. E l l e u c h , M. K e r k a n i and M. C h i h a o u i , J. Chem. SOC. Chem. Commun. 5 (1986) 402 - 403 K. E i c h l e r , E. Leupold, H. J. Arpe and H. B a l t e s , DE 3.420.707 (Dec. 05,1985), Hoechst AG H. J. Arpe and H. L i t t e r e r , EP 092.103 (Oct. 26, 1983) Hoechst AG F. J. Weigert, US 4.593. 124 (June 03,1986) du Pont de Nemours F. J. Weigert, J. Org. Chem. 52 (1987) 3296 - 3298 F. J. Weigert, J. Org. Chem. 51 (1986) 2653 - 2655 P. Cartraud, A. C o i n t o t , M. D u f o u r , N. S. Gnet, G. J o l y and J. Tejada, Appl. Catal. 21 (1986) 85 - 96 F. G. Dwyer i n W. R. Moser ( E d i t o r ) , " C a t a l y s i s o f Organic R e a c t i o n s " , M a r c e l Dekker Inc., New York, USA, 1981, pp. 73 - 94 P. I. Lewis, F. G. Dwyer, O i l Gas J. 75 (1977) 55 58 T. Yashima, K. Sato, T. Hayasaka, N. Hara, J. Catal. 26 (1972) 303 - 312 M. L. Unland, G. E. B a r k e r see C 7 7 1 51 71 J. M. Garces, G. E. V r i e l a n d , S. I. Bates and F. M. S c h e i d t , Stud. Surf. Sci. Catal. 20 (1985) 67 - 74 C. L a c r o i x , A. Deluzarche, A. Kiennemann and A. Boyer, Z e o l i t e s 4 (1984) 109 111 H. Kashiwagi, Y. F u j i k i and S. Enomoto, Chem. Pharm. B u l l . 30 (1982) 404 - 411 and pp. 2575 - 2578 P. Y. Chen, M. C. Chen, H. Y. Chu, N. S. Chang and T. K. Chuang, Stud. Surf. Sci. Catal. 28 (1986) 739 - 746 H. Sat0 and M. Tsuzuki, I P 62.195.350 (Febr. 21, 19861, I d e m i t s u Kosan Co. D. D. Dixon, EP 226. 781 ( J u l y 01, 19861, A i r Prod. Chem. Inc. R. Agrawal, S. A u v i l and M. Deeba, EP 240.018 (Oct. 07, 1987), A i r Prod, Chem. Inc. R. P i e r a n t o z z i , EP 245.797 (Nov. 19, 1987), A i r Prod. Chem. Inc.

-

-

-



COMPARISON OF THE ALKYLATION OF ANISOLE AND PHENOL WITH METHANOL ON PENTASIL AND ULTRASTABLE ZEOLITES

RUDY F. PARTON, JULIA M. JACOBS, HEIDI VAN OOTEGHEM and PETER A. JACOBS Laboratorium voor Oppervlaktechemie, KU Leuven, Kardinaal Mercierl aan 92, B3030, Heverlee (Leuven), Belgium

ABSTRACT The alkylation of anisole and phenol with methanol was measured in a microreactor at 473 K and at different contact times, using as catalysts pentasil and H-USY zeolites. Activity and selectivity results showed that monomolecular reactions are favoured on pentasil and bimolecular reactions on large-pore zeolites. The high selectivity o f o-cresol observed on the tenmembered-ring compared to H-USY zeolites is explained by the intramolecular rearrangement of anisole to o-cresol . INTRODUCTION The acid-catalysed a1 kylation of toluene with methanol over tenmembered-ring (10-MR) zeolites to obtain a para-enriched a1 kylate is now well established industrial practice [l-31. The methylation of phenol with methanol [4-91 or anisole [lo, 111 on zeolites gives a mixture of anisole, xylenols and cresols, rich in the ortho-isomer. Evidently, the selectivity of p-cresol is not improved by the use of pentasil-type zeolites. On H-ZSM-5, the o/p-cresol ratio is always higher than one whereas on Y zeolites o/p ratios significantly lower than one have been reported [12-141. On the contrary, a high p-selectivity in the methylanisole fraction is observed in the self-alkylation of anisole on H-ZSM-5 [15] as well as in the methylation of anisole with methanol [14]. In order to make p-cresol selectively by the use of shape selective zeolite catalysts, it is desirable to know the reaction network of the methylation of phenol with methanol and the influence of the zeolite structure on the different pathways. Recently, for A1P04-Ti02 catalysts an overall scheme of the phenol and anisole alkylation was reported [16, 171. On H-ZSM-5 a detailed study of anisole conversion showed three primary pathways [15]. The main pathway of cresol formation is the intramolecular rearrangement of anisole to o-cresol When the influence of the zeolite structure and acidity on the reaction network of the alkylation of phenol with methanol is known it should be possible to select and modify zeolite catalysts in order to obtain the desired isomer with high selectivity.

.

EXPERIMENT M a t e r i a1 s Two batches, (1) and ( 2 ) , o f ZSM-5 and a sample o f ZSM-11 w i t h a Si/A1 r a t i o o f 100 were s y n t h e s i z e d a c c o r d i n g t o e s t a b l i s h e d l i t e r a t u r e procedures [18, 191. A f t e r a i r c a l c i n a t i o n a t 823 K, subsequent ammonium exchange a t r e f l u x c o n d i t i o n s was done. A sample o f H-USY w i t h a framework S i / A l r a t i o o f 20 was r e c e i v e d f r o m Toyo Soda.

A n o t h e r sample o f H-USY was prepared by

steaming o f NH4-Y, purchased f r o m V e n t r o n as Nay, w i t h a Si/A1 r a t i o o f 2.46. Bot h

samples

are

denoted

as

H-USY(T)

framework Si/A1 r a t i o o f USY(V) was 4.3 reaction a l l

and

H-USY(V),

respectively.

The

as det ermined b y 2 9 S i NMR. Bef ore

z e o l i t e s were c a l c i n e d i n s i t u i n f l o w i n g oxygen.

Anisole,

phenol and methanol w i t h a p u r i t y o f a t l e a s t 99% were purchased f rom Janssen Chimica. Reac t io n procedure Time-on-stream (ToS) e x p e r i m e n t s i n t h e vapour phase were c a r r i e d o u t i n hydrogen, u s i n g a f i x e d - b e d c o n t i n u o u s f l o w r e a c t o r a t d i f f e r e n t c o n t a c t times , W/Fo,

and atmospheric p r e s s u r e . W s t ands f o r c a t a l y s t weight and Fo

f o r mo lar f l o w r a t e o f t h e f e e d a t t h e r e a c t o r e n t r a n c e . The z e o l i t e powder was pressed,

crushed,

s i e v e d and t h e 0.25-0.50

mm f r a c t i o n

retained for

f u r t h e r use. The vapour p r e s s u r e o f a n i s o l e , phenol and methanol was 1.3 kPa. The r e a c t i o n p r o d u c t s were analysed o n - l i n e by gas chromatography on a 2 m packed column from Supelco c o n t a i n i n g 0 . 1 % SP-1,000 on Carbopack C . RESULTS and DISCUSSION O v e r a l l a c t i v i t y i n t h e a l k v l a t i o n o f a n i s o l e w i t h methanol 100

-aR

80

.-C0 2 0

60

>

e

0 V

-

40

0 0

.-mC

z

/

10-

0 100

k d I

150

b/ M.I.B.K.

/'

0

E

> I-

'Light hydrocar

Zeolites As Catalysts, Sorbents, and Detergent Builders: Applications and Innovations : Proceedings (Studies in Surface Science and Catalysis)

Preparation of Catalysts VII (Studies in Surface Science and Catalysis)

Catalysis by Zeolites: International Symposium Proceedings (Studies in surface science and catalysis)

Catalysts for Upgrading Heavy Petroleum Feeds, Volume 169 (Studies in Surface Science and Catalysis) (Studies in Surface Science and Catalysis)

Adsorption on New and Modified Inorganic Sorbents (Studies in Surface Science and Catalysis)

Preparation of Catalysts: 2nd: International Symposium Proceedings (Studies in Surface Science and Catalysis)

Catalysts in Petroleum Refining and Petrochemical Industries 1995 (Studies in Surface Science and Catalysis)

New Developments in Selective Oxidation by Heterogeneous Catalysis: Proceedings (Studies in Surface Science and Catalysis)

Fluid Catalytic Cracking VII:, Volume 166: Materials, Methods and Process Innovations (Studies in Surface Science and Catalysis) (Studies in Surface Science and Catalysis)

Catalysis: An Integrated Approach to Homogenous, Heterogenous and Industrial Catalysis (Studies in Surface Science and Catalysis)

Catalysis and Adsorption by Zeolites

Advanced Zeolite Science and Applications, Volume 85 (Studies in Surface Science and Catalysis)

Synthesis of High-Silica Aluminosilicate Zeolites (Studies in Surface Science and Catalysis)

Fluid Catalytic Cracking V (Studies in Surface Science and Catalysis)

Catalytic Polymerization of Olefins (Studies in Surface Science and Catalysis)

Photochemistry on Solid Surfaces (Studies in Surface Science and Catalysis)

Fluid Catalytic Cracking V (Studies in Surface Science and Catalysis)

Zeolites and Microporous Crystals: Proceedings of the International Symposium on Zeolites and Microporous Crystals, Nagoya, August 22-25, 1993 (Studies in Surface Science and Catalysis)

Zeolites in Industrial Separation and Catalysis

Surface and nanomolecular catalysis

Past and Present in DeNOx Catalysis: From Molecular Modelling to Chemical Engineering, Volume 171 (Studies in Surface Science and Catalysis) (Studies in Surface Science and Catalysis)

Surface and Nanomolecular Catalysis

Zeolites in Industrial Separation and Catalysis

Scientific Bases for the Preparation of Heterogeneous Catalysts (Studies in Surface Science and Catalysis)

Spectroscopic Characterization of Heterogeneous Catalysts (Studies in Surface Science and Catalysis)

Zeolites in Industrial Separation and Catalysis

Zeolites and Catalysis: Synthesis, Reactions and Applications (2 Volume set)

Zeolites, science and technology

Catalysis and Automotive Pollution Control III (Studies in Surface Science and Catalysis, Volume 96)

Catalysis and Automotive Pollution Control (Studies in Surface Science and Catalysis)

Catalysis by Metals and Alloys (Studies in Surface Science and Catalysis)

Zeolites As Catalysts, Sorbents, and Detergent Builders: Applications and Innovations : Proceedings (Studies in Surface Science and Catalysis)

Preparation of Catalysts VII (Studies in Surface Science and Catalysis)

Catalysis by Zeolites: International Symposium Proceedings (Studies in surface science and catalysis)

Catalysts for Upgrading Heavy Petroleum Feeds, Volume 169 (Studies in Surface Science and Catalysis) (Studies in Surface Science and Catalysis)

Adsorption on New and Modified Inorganic Sorbents (Studies in Surface Science and Catalysis)

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Catalysts in Petroleum Refining and Petrochemical Industries 1995 (Studies in Surface Science and Catalysis)

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Past and Present in DeNOx Catalysis: From Molecular Modelling to Chemical Engineering, Volume 171 (Studies in Surface Science and Catalysis) (Studies in Surface Science and Catalysis)

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