Structured Catalysts and Reactors Second Edition © 2006 by Taylor & Francis Group, LLC CHEMICALINDUSTRIES ASeries of Reference Books and Textbooks Series Editor JAMES G. SPEIGHT Laramie, Wyoming Founding Editor HEINZ HEINEMANN Berkeley, California 1. Fluid Catalytic Cracking with Zeolite Catalysts,Paul B. Venuto and E. Thomas Habib, Jr. 2. Ethylene: Keystone to the Petrochemical Industry,Ludwig Kniel, Olaf Winter, and Karl Stork 3. The Chemistry and Technology of Petroleum,James G. Speight 4. The Desulfurization of Heavy Oils and Residua,James G. Speight 5. Catalysis of Organic Reactions,edited by William R. Moser 6. Acetylene-Based Chemicals from Coal and Other Natural Resources, Robert J. Tedeschi 7. Chemically Resistant Masonry,Walter Lee Sheppard, Jr. 8. Compressors and Expanders: Selection and Application for the Process Industry,Heinz P. Bloch, Joseph A. Cameron, Frank M. Danowski, Jr., Ralph James, Jr., Judson S. Swearingen, and Marilyn E. Weightman 9. Metering Pumps: Selection and Application,James P. Poynton 10. Hydrocarbons from Methanol,Clarence D. Chang 11. Form Flotation: Theory and Applications,Ann N. Clarke and David J. Wilson 12. The Chemistry and Technology of Coal,James G. Speight 13. Pneumatic and Hydraulic Conveying of Solids,O. A. Williams 14. Catalyst Manufacture: Laboratory and Commercial Preparations, Alvin B. Stiles 15. Characterization of Heterogeneous Catalysts,edited by Francis Delannay 16. BASIC Programs for Chemical Engineering Design,James H. Weber 17. Catalyst Poisoning,L. Louis Hegedus and Robert W. McCabe 18. Catalysis of Organic Reactions,edited by John R. Kosak 19. Adsorption Technology: A Step-by-Step Approach to Process Evaluation and Application,edited by Frank L. Slejko 20. Deactivation and Poisoning of Catalysts,edited by Jacques Oudar and Henry Wise © 2006 by Taylor & Francis Group, LLC 21. Catalysis and Surface Science: Developments in Chemicals from Methanol, Hydrotreating of Hydrocarbons, Catalyst Preparation, Monomers and Polymers, Photocatalysis and Photovoltaics,edited by Heinz Heinemann and Gabor A. Somorjai 22. Catalysis of Organic Reactions,edited by Robert L. Augustine 23. Modern Control Techniques for the Processing Industries,T. H. Tsai, J. W. Lane, and C. S. Lin 24. Temperature-Programmed Reduction for Solid Materials Characterization, Alan Jones and Brian McNichol 25. Catalytic Cracking: Catalysts, Chemistry, and Kinetics, Bohdan W. Wojciechowski and Avelino Corma 26. Chemical Reaction and Reactor Engineering,edited by J. J. Carberry and A. Varma 27. Filtration: Principles and Practices: Second Edition,edited by Michael J. Matteson and Clyde Orr 28. Corrosion Mechanisms,edited by Florian Mansfeld 29. Catalysis and Surface Properties of Liquid Metals and Alloys,Yoshisada Ogino 30. Catalyst Deactivation,edited by Eugene E. Petersen and Alexis T. Bell 31. Hydrogen Effects in Catalysis: Fundamentals and Practical Applications, edited by Zoltán Paál and P. G. Menon 32. Flow Management for Engineers and Scientists,Nicholas P. Cheremisinoff and Paul N. Cheremisinoff 33. Catalysis of Organic Reactions,edited by Paul N. Rylander, Harold Greenfield, and Robert L. Augustine 34. Powder and Bulk Solids Handling Processes: Instrumentation and Control, Koichi Iinoya, Hiroaki Masuda, and Kinnosuke Watanabe 35. Reverse Osmosis Technology: Applications for High-Purity-Water Production, edited by Bipin S. Parekh 36. Shape Selective Catalysis in Industrial Applications,N. Y. Chen, William E. Garwood, and Frank G. Dwyer 37. Alpha Olefins Applications Handbook,edited by George R. Lappin and Joseph L. Sauer 38. Process Modeling and Control in Chemical Industries,edited by Kaddour Najim 39. Clathrate Hydrates of Natural Gases,E. Dendy Sloan, Jr. 40. Catalysis of Organic Reactions,edited by Dale W. Blackburn 41. Fuel Science and Technology Handbook,edited by James G. Speight 42. Octane-Enhancing Zeolitic FCC Catalysts,Julius Scherzer 43. Oxygen in Catalysis, Adam Bielanski and Jerzy Haber 44. The Chemistry and Technology of Petroleum: Second Edition, Revised and Expanded,James G. Speight 45. Industrial Drying Equipment: Selection and Application,C. M. van’t Land 46. Novel Production Methods for Ethylene, Light Hydrocarbons, and Aromatics, edited by Lyle F. Albright, Billy L. Crynes, and Siegfried Nowak 47. Catalysis of Organic Reactions, edited by William E. Pascoe 48. Synthetic Lubricants and High-Performance Functional Fluids, edited by Ronald L. Shubkin 49. Acetic Acid and Its Derivatives, edited by Victor H. Agreda and Joseph R. Zoeller 50. Properties and Applications of Perovskite-Type Oxides, edited by L. G. Tejuca and J. L. G. Fierro 51. Computer-Aided Design of Catalysts, edited by E. Robert Becker and Carmo J. Pereira © 2006 by Taylor & Francis Group, LLC 52. Models for Thermodynamic and Phase Equilibria Calculations, edited by Stanley I. Sandler 53. Catalysis of Organic Reactions, edited by John R. Kosak and Thomas A. Johnson 54. Composition and Analysis of Heavy Petroleum Fractions, Klaus H. Altgelt and Mieczyslaw M. Boduszynski 55. NMR Techniques in Catalysis, edited by Alexis T. Bell and Alexander Pines 56. Upgrading Petroleum Residues and Heavy Oils, Murray R. Gray 57. Methanol Production and Use, edited by Wu-Hsun Cheng and Harold H. Kung 58. Catalytic Hydroprocessing of Petroleum and Distillates, edited by Michael C. Oballah and Stuart S. Shih 59. The Chemistry and Technology of Coal: Second Edition, Revised and Expanded,James G. Speight 60. Lubricant Base Oil and Wax Processing, Avilino Sequeira, Jr. 61. Catalytic Naphtha Reforming: Science and Technology, edited by George J. Antos, Abdullah M. Aitani, and José M. Parera 62. Catalysis of Organic Reactions, edited by Mike G. Scaros and Michael L. Prunier 63. Catalyst Manufacture,Alvin B. Stiles and Theodore A. Koch 64. Handbook of Grignard Reagents, edited by Gary S. Silverman and Philip E. Rakita 65. Shape Selective Catalysis in Industrial Applications: Second Edition, Revised and Expanded, N. Y. Chen, William E. Garwood, and Francis G. Dwyer 66. Hydrocracking Science and Technology, Julius Scherzer and A. J. Gruia 67. Hydrotreating Technology for Pollution Control: Catalysts, Catalysis, and Processes, edited by Mario L. Occelli and Russell Chianelli 68. Catalysis of Organic Reactions, edited by Russell E. Malz, Jr. 69. Synthesis of Porous Materials: Zeolites, Clays, and Nanostructures, edited by Mario L. Occelli and Henri Kessler 70. Methane and Its Derivatives, Sunggyu Lee 71. Structured Catalysts and Reactors, edited by Andrzej Cybulski and Jacob A. Moulijn 72. Industrial Gases in Petrochemical Processing, Harold Gunardson 73. Clathrate Hydrates of Natural Gases: Second Edition, Revised and Expanded, E. Dendy Sloan, Jr. 74. Fluid Cracking Catalysts, edited by Mario L. Occelli and Paul O’Connor 75. Catalysis of Organic Reactions, edited by Frank E. Herkes 76. The Chemistry and Technology of Petroleum: Third Edition, Revised andExpanded, James G. Speight 77. Synthetic Lubricants and High-Performance Functional Fluids: Second Edition, Revised and Expanded, Leslie R. Rudnick and Ronald L. Shubkin 78. The Desulfurization of Heavy Oils and Residua,Second Edition, Revised and Expanded, James G. Speight 79. Reaction Kinetics and Reactor Design: Second Edition, Revised and Expanded, John B. Butt 80. Regulatory Chemicals Handbook, Jennifer M. Spero, Bella Devito, and Louis Theodore 81. Applied Parameter Estimation for Chemical Engineers, Peter Englezos and Nicolas Kalogerakis 82. Catalysis of Organic Reactions,edited by Michael E. Ford 83. The Chemical Process Industries Infrastructure: Function and Economics, James R. Couper, O. Thomas Beasley, and W. Roy Penney 84. Transport Phenomena Fundamentals, Joel L. Plawsky © 2006 by Taylor & Francis Group, LLC 85. Petroleum Refining Processes, James G. Speight and Baki Özüm 86. Health, Safety, and Accident Management in the Chemical ProcessIndustries, Ann Marie Flynn and Louis Theodore 87. Plantwide Dynamic Simulators in Chemical Processing and Control, William L. Luyben 88. Chemicial Reactor Design, Peter Harriott 89. Catalysis of Organic Reactions, edited by Dennis G. Morrell 90. Lubricant Additives: Chemistry and Applications, edited by Leslie R. Rudnick 91. Handbook of Fluidization and Fluid-Particle Systems, edited by Wen-Ching Yang 92. Conservation Equations and Modeling of Chemical and Biochemical Processes, Said S. E. H. Elnashaie and Parag Garhyan 93. Batch Fermentation: Modeling,Monitoring, and Control, Ali Çinar, Gülnur Birol, Satish J. Parulekar, and Cenk Ündey 94. Industrial Solvents Handbook,Second Edition, Nicholas P. Cheremisinoff 95. Petroleum and Gas Field Processing, H. K. Abdel-Aal, Mohamed Aggour, and M. Fahim 96. Chemical Process Engineering: Design and Economics, Harry Silla 97. Process Engineering Economics, James R. Couper 98. Re-Engineering the Chemical Processing Plant: Process Intensification, edited by Andrzej Stankiewicz and Jacob A. Moulijn 99. Thermodynamic Cycles: Computer-Aided Design and Optimization, Chih Wu 100. Catalytic Naptha Reforming: Second Edition, Revised and Expanded, edited by George T. Antos and Abdullah M. Aitani 101. Handbook of MTBE and Other Gasoline Oxygenates, edited by S. Halim Hamid and Mohammad Ashraf Ali 102. Industrial Chemical Cresols and Downstream Derivatives, Asim Kumar Mukhopadhyay 103. Polymer Processing Instabilities: Control and Understanding, edited by Savvas Hatzikiriakos and Kalman B. Migler 104. Catalysis of Organic Reactions, John Sowa 105. Gasification Technologies: A Primer for Engineers and Scientists, edited by John Rezaiyan and Nicholas P. Cheremisinoff 106. Batch Processes, edited by Ekaterini Korovessi and Andreas A. Linninger 107. Introduction to Process Control, Jose A. Romagnoli and Ahmet Palazoglu 108. Metal Oxides: Chemistry and Applications, edited by J. L. G. Fierro 109. Molecular Modeling in Heavy Hydrocarbon Conversions, Michael T. Klein, Ralph J. Bertolacini, Linda J. Broadbelt, Ankush Kumar and Gang Hou 110. Structured Catalysts and Reactors, Second Edition, edited by Andrzej Cybulski and Jacob A. Moulijn © 2006 by Taylor & Francis Group, LLC Structured Catalysts and Reactors Second Edition edited by Andrzej Cybulski Jacob A. Moulijn Boca Raton London New York A CRC title, part of the Taylor & Francis imprint, a member of the Taylor & Francis Group, the academic division of T&F Informa plc. © 2006 by Taylor & Francis Group, LLC Published in 2006 by CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2006 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group No claim to original U.S. Government works Printed in the United States of America on acid-free paper 10 9 8 7 6 5 4 3 2 1 International Standard Book Number-10: 0-8247-2343-0 (Hardcover) International Standard Book Number-13: 978-0-8247-2343-9 (Hardcover) Library of Congress Card Number 2005049124 This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the validity of all materials or for the consequences of their use. No part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright.com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC) 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging-in-Publication Data Structured catalysts and reactors / [edited by] Andrzej Cybulski and Jacob A. Moulijn.--2nd ed. p. cm. -- (Chemical industries series ; v. 110) Includes bibliographical references. ISBN 0-8247-2343-0 (acid-free paper) 1. Catalysts. 2. Chemical reactors. I. Cybulski, Andrzej, 1938- II. Moulijn, Jacob A. III. Chemical industries ; v. 110. TP156.C35S77 2005 660'.2995--dc22 2005049124 Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com Taylor & Francis Group and the CRC Press Web site at is the Academic Division of Informa plc. http://www.crcpress.com © 2006 by Taylor & Francis Group, LLC Preface Heterogeneous catalyticprocessesareamongthemain ways todecreasetheconsumptionof rawmaterialsinchemicalindustriesandtodecreasetheemissionofpollutantsofallkindsto the environment via an increase in process selectivity. Selectivity can be improved by the modification of catalyst composition and surface structure and/or by the modification of pellet dimensions, shape, and texture, i.e., pore size distribution, pore shape, length, and cross-sectional surface area (distribution). Until recently, the limiting factor in the latter modificationshasbeentheparticles’size,towhichthelengthofdiffusioninporesisrelated. The size should not be too small because of the significantly higher pressure drop for such small particles. Shell catalysts, which contain catalytic species concentrated near the outer particles’ surface, are a remedy for improving selectivity and keeping pressure drop at a reasonable level. Pressure drop can be the limiting factor even for such catalysts, e.g., when largequantitiesofrawmaterialsmust beprocessedorwhen thehigher pressuredropresults in a significantly higher consumption of raw materials. For instance, converting huge amounts of natural gas in remote areas would require equipment characterized by low pressure drop. Otherwise the cost of processing would be too high to make the process economical.Toohighapressuredropincatalyticcarmufflerswouldresultinanincreasein fuelconsumptionbyseveralpercent.Thiswouldmeanaseveral-percent-higherconsumption of crude oil for transportation. An inherent feature of conventional packed-bed reactors is their random and structural maldistributions. A structural maldistribution in fixed-bed reactorsoriginatesfromthelooserpackingofparticlesnearthereactorwalls.Thisresultsina tendency to bypass the core of the bed, even if the initial distribution of fluid(s) is uniform. The uniformly distributed liquid tends to flow to the walls, and this can drastically alter its residence time from the design value. Random maldistributions result in: (1) a nonuniform access of reactants to the catalytic surface, worsening the overall process performance, and (2) unexpected hot spots and thermal runaways of exothermic reactions (mainly in three- phase reactions). Structuredcatalysts(reactors)arepromisingasfarastheeliminationofthesedrawbacks of fixed beds is concerned. Three basic kinds of structured catalysts can be distinguished: 1. Monolithic catalysts (honeycomb catalysts), in the form of continuous unitary structures that contain small passages. The catalytically active material is present on or inside the walls of these passages. In the former case, a ceramic or metallic supportiscoatedwithalayerofmaterialinwhichactiveingredientsaredispersed. 2. Membrane catalysts are structures with permeable walls between passages. The membrane walls exhibit selectivity in transport rates for the various components present. A slow radial mass transport can occur, driven by diffusion or solution/ diffusion mechanisms in the permeable walls. 3. Arranged catalysts. Particulate catalysts arranged in arrays belong to this class of structured catalysts. Another group of arranged catalysts are structural catalysts, derivedfromstructuralpackingsfordistillationandabsorptioncolumnsandstatic mixers.Thesearestructuresconsistingofsuperimposedsheets,possiblycorrugated beforestacking.Thesheetsarecoveredbyanappropriatecatalystsupportinwhich active ingredients are incorporated. The structure is an open cross-flow structure characterized by intensive radial mixing. © 2006 by Taylor & Francis Group, LLC x Preface Usually, structured catalysts are structures of large void fraction ranging from 0.7 to more than 0.9, compared to 0.5 in packed beds. The path the fluids follow in structured reactors is much less twisted (e.g., straight channels in monoliths) than that in conventional reactors. Finally, structured reactors are operated in a different hydrodynamic regime. For single-phase flow the regime is laminar, and the eddies characteristic of packed beds are absent. For multiphase systems various regimes exist, but here also eddies are absent. For these reasons, the pressure drop in structured catalysts is significantly lower than that in randomlypackedbedsofparticles.Indeed, thepressuredropinmonolithic reactorsisupto two orders of magnitude lower than that in packed-bed reactors. Catalytic species are incorporated either into a very thin layer of a porous catalyst supportdepositedonthestructuredelementsorintothethinelementsthemselves.Theshort diffusion distance inside the thin layer of the structured catalysts results in higher catalyst utilization and can contribute to an improvement of selectivity for processes controlled by masstransferwithinthecatalyticlayer.Incontrasttoconventionalpacked-bedreactors,the thickness of the catalytic layer in monolithic reactors can be significantly reduced with no penalty paid for the increase in pressure drop. Membrane catalysts provide a unique opportunitytosupplyreactantstothereactionmixturegraduallyalongthereactionrouteor to withdraw products from the reaction mixture as they are formed. The former mode of carrying out complex reactions might be very effective in controlling undesired reactions whose rates are strongly dependent on the concentration of the added reactant. The latter mode might result in higher conversions for reversible reactions, which are damped by products.Theuseofcatalyticmembranesoperatedinanyofthesemodescanalsocontribute to significant improvement in selectivity. The regular structure of the arranged catalysts prevents the formation of the random maldistributions characteristic of beds of randomly packed particles. This reduces the probability of the occurrence of hot spots resulting from flow maldistributions. Scale-up of monolithic and membrane reactors can be expected to be straightforward, since the conditions within the individual channels are scale invariant. Finally, structured catalysts and reactors constitute a significant contribution to the search for better catalytic processes via improving mass transfer in the catalytic layer and thus improving activity and selectivity, decreasing operating costs through lowering the pressure drop, and eliminating maldistributions. Structured catalysts, mainly monolithic ones, are now used predominantly in environ- mental applications, first of all in the cleaning of automotive exhaust gases. Monolithic reactors have become the most commonly used sort of chemical reactors: nearly a billion smallmonolithicreactorsaremovingwithourcars!Monolithiccleanersoffluegasesarenow standardunits.Monolithiccatalystsarealsoclosetocommercializationinthecombustionof fuelsforgasturbines,boilers,heaters,etc.ThecatalyticcombustionreducesNO formation, x andtheuseoflow-pressure-dropcatalystsmakestheprocessmoreeconomical.Somespecial features of monolithic catalysts make the burning of low-heating-value (LHV) fuels in monolithic units much easier than in packed beds of particulate catalysts. There are some characteristics that make structured catalysts also of interest for three-phase reactions. Severalthree-phaseprocessesareinthedevelopmentstage.Catalyticoxidationoforganicsin wastewater is currently operated in demonstration plants. One process, the hydrogenation step in the production of hydrogen peroxide using the alkylanthraquinone process, has already reached full scale, with several plants in operation. Interest in structured catalysts is steadily increasing due to the already proven, and potential, advantages of these catalysts. A number of review articles regarding different aspects of structured catalysts have been published in the last decade [see F. Kapteijn, J.J. Heiszwolf, T.A. Nijhuis, and J.A. Moulijn, Cattech, 3, 24–41, 1999; A. Cybulski and J.A. Moulijn, Catal. Rev. Sci. Eng., 36, 179–270, 1994; G. Saracco and V. Specchia, Catal. © 2006 by Taylor & Francis Group, LLC Preface xi Rev. Sci. Eng., 36, 305–384, 1994; H.P. Hsieh, Catal. Rev. Sci. Eng., 33, 1–70, 1991; S. Irandoust and B. Anderson, Catal. Rev. Sci. Eng., 30, 341–392, 1988; and L.D. Pfefferle and W.C. Pfefferle, Catal. Rev. Sci. Eng., 29, 219–267, 1987]. Thesearticlesdonotcoverthewholeareaofstructuredcatalystsandreactors.Moreover, the science and applications of structured catalysts and reactors are developing very fast. Therefore, some eight years ago we decided to edit a book on structured catalysts and reactors. In 1998 it was published. The time has now come for an updated version. In this edition an attempt has been made to give detailed information on all structures known to date and on all aspects of structured catalysts and reactors containing them: catalyst preparation and characterization, catalysts and process development, modeling and optimization, and finally reactor design and operation. As such, the book is dedicated to allreaderswhoareinvolvedinthedevelopmentofcatalyticprocesses,fromR&Dtoprocess engineering. A very important area of structuring in catalysis is that directed at a catalytic surface,microstructure,andstructuringtheshapeandsizeofthecatalyticbodies.Thisareais essentially covered by publications concerning a more fundamental approach to hetero- geneouscatalysis.Alotoftherelevantinformationisscaledependentand,asaconsequence, is not unique to structured catalytic reactors. Therefore, these activities are described only briefly in this book. The book starts with an overview on structured catalysts (Chapter 1). The rest of the book is divided in four parts. The first three parts deal with structures differing from each other significantly in conditions for mass transfer in the reaction zone. The fourth part is dedicated to catalyst design and preparation. Part I deals with monolithic catalysts. Chapters 2 and 3 deal with the configurations, microstructure, physical properties, and manufacture of ceramic and metallic monoliths. Monolithiccatalystsforcleaningtheexhaustgasfromgasoline-fueledenginesaredealtwith in Chapter 4, including fundamentals and exploitation experience. Chapters 5 and 6 are devoted to commercial and developmental catalysts for protecting the environment. The subject of Chapter 5 is the treatment of volatile organic carbon (VOC) emissions from stationary sources. In Chapter 6 fundamentals and applications of monoliths for selective catalyticreductionofNO aregiven.Unconventionalreactorsusedinthisfield(reverse-flow x reactors,rotatingmonoliths)arealso discussed.Materials,activity,andstabilityofcatalysts for catalytic combustion and practical applications of monolithic catalysts in this area are discussed in Chapter 7. The use of monolithic catalysts for the synthesis of chemicals is discussed in Chapter 8. Chapter 9 is devoted to the modeling of monolithic catalysts for two-phaseprocesses(gaseousreactants/solidcatalyst).Chapters10–13dealwiththree-phase monolithicprocesses.Bothcatalyticandengineeringaspectsoftheseprocessesarediscussed. Arranged catalysts allowing for convective mass transfer over the cross section of the reactor are discussed in Part II. Conventional particulate catalysts arranged in arrays are dealtwithinChapter14.Currentandpotentialapplicationsoforderedstructuresofdifferent kinds (parallel-passage and lateral-flow reactors) are mentioned. Chapter 15 is devoted to structuredpackingswithrespecttoreactivedistillationwithemphasisonSulzerKatapak-SP packings. Part III of the book provides information about structured catalysts of the monolithic type with permeable walls, i.e., catalytically active membranes. Chapter 16 deals with catalytic filters for flue gas cleaning. Catalytic membranes create a unique opportunity to couple processes opposite in character (e.g., hydrogenation/dehydrogenation, endothermic/exothermic) via the combina- tion of reaction and separation. Catalytic membranes can allow for the easy control of reactant addition or product withdrawal along the reaction route. Chapter 17 deals with membrane reactors with metallic walls permeable to some gases. The properties of metallic membranes,permeationmechanismsinmetallicmembranes,thepreparationofmembranes, © 2006 by Taylor & Francis Group, LLC