Fluid Catalytic Cracking: Science and Technology PDF
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Studies in Surface Science and Catalysis Advisory Editors: B. Delmon and J.T. Yates Vol. 76 .FLUID CATALYTIC CRACKING: SCIENCE AND TECHNOLOGY Editors John S. Magee Catalytic Science Associates, 12205 Mount Albert Road, Ellicott City, Maryland 2 1042, U.S.A. (Formerly Director of Technology,K atalistiks International,A Unit of UOR Baltimore, Maryland, U.S.A.) Maurice M. Mitchell, Jr. Ohio University Southern Campus, 1804 Liberty Avenue, Ironton, Ohio 45638, U.S.A.( Formerly Vice President, Research and Development, Ashland Petroleum Company, Ashland, Kentucky, U.S.A.) ELSEVIER Amsterdam -L ondon -N ew Vork -Tokyo 1993 ELSEVIER SCIENCE PUBLISHERS B.V. Sara Burgerhartstraat 25 P.O. Box211, IOOOAEAmsterdam,The Netherlands ISBN: 0-444-89037-8 t3 1993 Elsevier Science Publishers B.V. 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., Copyright & Permis- sions Department, P.O. Box 521,1000AM Amsterdam,The Netherlands. Special regulations for readers in the U.S.A. - 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 U.S.A. All other copyright questions, including photocopying outside of the U.S.A., should be referred to the publisher. No responsibility is assumed by the publisher for any injury and/or damage to persons or pro- pertyas a matter of products liability, negligenceorotherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein. This book is printed on acid-free paper. Printed in The Netherlands V Preface According to the table of contents, Fluid Catalytic Cracking: Science & Technology, is concerned with fifteen different, though related, topics. While this is true, the reader is encouraged to consider the primary focus of the book as a whole to be on performance--performance of the catalyst, of its surface, of the FCC unit, of the feedstocks employed, of the analytical methods used to characterize the catalysts, and of environmentally directed regulations that govern the production of transportation fuels from petroleum. The authors and the editors have tried to produce a volume that will fill the need for a comprehensive survey of this major field of petroleum processing while maintaining a high level of thoughtful brevity. Thoughtful brevity is one of those things that is difficult to define, but anyone who has sat through a thirty-minute sermon or read a 100 page final report knows what it is. The subject matter of the book is intended to deal with several important performance issues: What does the catalyst itself do as a function of its chemical and physical composition? How does molecular structure influence performance? How7 do metal contaminants influence performance? How does the FCC unit itself influence performance? How will environmental legislation influence the way the overall catalyst and cracking unit system must perform? The emphasis on catalyst performance, particularly commercial performance, essentially dictated that the chapter authors be experienced industrial catalytic chemists and engineers. However, each author approached the task with a clear- cut obligation to connect the roots of the science of FCC catalysis with the technology. In the case of FCC catalysis, the basic foundation was formed from virtually equal parts of pure science and practical technology, with an enormous sense of urgency caused by the transportation fuel needs of World War 11. Pure research in FCC catalysis was not neglected, and the pioneering work of Eugene Houdry, Paul Emmett, and Paul Weiss, to name but a few, broadened the base on which the industry was built. Evolutionary changes were followed by the revolution of zeolite-containing FCC catalysts. For this we all owe a debt to Charles Plank and Edward Rosinski. The editors have chosen to document the revolution to date with fifteen chapters of FCC science and technology. As stated before, each author was charged with the task of documenting FCC catalyst performance from the standpoint of both the science and the technology involved in performance. We feel that performance is so important that we have included two chapters and part of a third on catalyst evaluation. Each offers a somewhat different viewpoint on vi how catalyst performance should be evaluated in the laboratory. In our opinion all three offer enough value to be considered equally by any serious worker striving to understand how a catalyst can be made to perform in the laboratory in a manner predictive of its commercial operation. It is also very clear today that the environmental impact of the use of fossil fuels in the transportation sector can have a profound effect on FCC catalysis. Superficially, there seems little connection to the actual science of FCC catalysis, but, as an example, an entire supporting industry has grown based on the catalytic oxidation of CO to C02 and the catalytic elimination of oxides of sulfur and nitrogen from stack gases from the FCC unit regenerator. Two chapters deal with the relationship of FCC catalysis and the real world of cars, planes, and plastics: Chapter 11 on FCC unit design and operational control, and Chapter 12 on the influences of the structural formula of the hydrocarbon being cracked and cracked-product molecular structure. The science of FCC catalysis is amply treated in Chapters 2,3,5, and 6. Here the nature of catalytic sites, their influence on catalyst performance, the structure and complexity involved with the zeolite component of the catalyst, and the instrumental techniques involved in surface and structural analysis are described. As is always the case, and justly so, we would add that the editors are pleased to acknowledge the many people who contributed time, effort, and above all, thought, to this project: The authors--in reality the book is theirs. The publishers-their approach to the hundreds of small and large problems in putting these pages between covers was always both professional and understanding. The critics--our wives, Niki and Marilyn, who encouraged us to complete the project; Dr. G. M. Woltermann, who critically read the text; and Drs. Anonymous, the authors’ peers, who reviewed all of the chapters. These latter catalyst professionals know who they are and rightly deserve the high esteem in which they are held by J.S.M. and M.M.M., Jr. John S. Magee Ellicott City, Maryland Maurice M. Mitchell, Jr. Ashland, Kentucky ix List of Contributors A.G. ASHTON BP International Limited Sunbury-on-Thames Middlesex, England TW 167LN A.A. AVIDAN Mobil Research and Development Corp. P.O. Box 480 Paulsboro, New Jersey 08066 A. BHATTACHARYYA Amoco Chemical Company P.O. Box 3011 Naperville, Illinois 60566 W.A. CRONKRIGHT The M W. Kellogg Company 16200 Park Row Houston, Texas 77084 T.F. DEGNAN Mobil Research and Development Corp. P.O. Box 480 Paulsboro, New Jersey 08066 P.K. DOOLIN Ashland Petroleum Company P.O. Box 391 Ashland, Kentucky 41114 F.G. DWYER Mobil Research and Development Corp. P.O. Box 480 Paulsboro, New Jersey 08066 R.E. EVANS Amoco Oil Company 200 E. Randolph Chicago, Illinois 60601 S.D. GRIFFITH UOP 25 East Algonquin Road Des Plaines, Illinois 60017 D.H. HARRIS Akzo Chemicals Inc. 3250 E. Washington Blvd. Los Angeles, California 90023 C.L. HEMLER UOP 25 East Algonquin Road Des Plaines, Illinois 60017 X J.F. HOFFMAN Ashland Petroleum Company P.O. Box 391 Ashland, Kentucky 41 114 A. HUMPHRIES Akzo Chemicals Inc. 3250 E. Washington Blvd. Los Angeles, California 90023 W.S. LETZSCH Refining Process Services 4052 Firefly Way Ellicott City, Maryland 21042 D.A. LOMAS UOP 25 East Algonquin Road Des Plaines, Lllinois 60017 J.S. MAGEE Catalytic Science Associates 12205 Mount Albert Road Ellicott City, Maryland 21042 J.B. MCLEAN Engelhard Corporation 1800 St. James Place Houston, Texas 77056 M.M. MITCHELL, JR. Ohio University Southern Campus 1804 Liberty Avenue Ironton, Ohio 45638 H.F. MOORE Ashland Petroleum Company P.O. Box 391 Ashland, Kentucky 41114 E.L. MOOREHEAD The M.W. Kellogg Company 16200 Park Row Houston, Texas 77084 R.H. NIELSEN Ashland Petroleum Company P.O. Box 391 Ashland, Kentucky 411 14 P. O'CONNOR Akzo Chemicals B.V. P.O. Box 975 3800 AZ Amersfoort, The Netherlands xi A.W. PETERS W.R. Grace & Co.- Conn. 7379 Route 32 Columbia, Maryland 21044 G.P. QUINN Amoco Oil Company 200 E. Randolph Chicago, Illinois 60601 J. SCHERZER Unocal Science and Technology Division 376 South Valencia Avenue, P.O. Box 76 Brea, California 92621 L.L. UPSON UOP 25 East Algonquin Road Des Plaines, Illinois 60017 D.E.W. VAUGHAN Exxon Research and Engineering Co. Rt. 22 East Annandale, New Jersey 08801 G.M. WOLTERMANN The PQ Corporation 280 Cedar Grove Road Conshohocken, Pennsylvania 19428 J.S. YO0 Amoco Chemical Company P.O. Box 3011 Naperville, Illinois 60566 G.W. YOUNG W.R Grace & Co.- Conn. 7379 Route 32 Columbia, Maryland 21044 J.S. Magee and M.M. Mitchell, Jr. Fluid Catalytic Cracking: Science and Technology 1 Studies in Surface Science and Catalysis, Vol. 76 0 1993 Elsevier Science Publishers B.V. All rights reserved. CHAPTER 1 ORIGIN, DEVELOPMENT AND SCOPE OF FCC CATALYSIS AMOS A. AVIDAN Mobil Research and Development Corporation Paulsboro Research Laboratory P. 0. Box 480 Paulsboro, New Jersey 08066-0480 U.S.A. 1. INTRODUCTION No other petroleum refining process, except for physical separation by distillation, has had a longer history, or more of an impact on the industry than cracking of heavy hydrocarbon molecules to lighter ones. The increasing use of automobiles in the beginning of the "Petroleum Century" quickly consumed available "natural" gasoline, and to meet the needs, petroleum companies have been finding and producing more crude oil. But complex supply and distribution considerations, coupled with recurring "energy crises", have pushed refiners to upgrade less valuable petroleum products to gasoline. This need spurred William Burton, of crude-poor Standard Oil Company of Indiana, to commercialize the first thermal cracking process in 1913. Two other methods to upgrade heavy-ends to gasoline were developed later: catalytic cracking and hydrocracking.( 1) Route Pressure First Commercialization Current Status Thermal: Thermal Low 5 major processes from Coking,visbreaking Cracking 1913 to 1936 Catalytic: Catalytic Low Houdry process, 1936 FCC is a major Cracking (following unsuccessful refinery upgrading McAfee process, 1915) process Hydrocracking High Many attempts prior HDC complements to modern HDC, 1962 and competes with FCC 2 A major inefficiency in heavy-ends upgrading processes is the production of low- value coke. The three process routes have dealt differently with this problem. Hydrocracking suppresses coke formation by recirculating hydrogen at high pressure, while Houdry discovered that burning coke restores catalyst activity in catalytic cracking. Three major chemical reaction engineering solutions have been applied to implementing Houdry’s invention: fixed-bed (1936-1941), moving-bed (1941-1960), and fluid-bed (1942-today). The dates in parenthesis represent the heydays of each process. 1.1 What is Catalytic Cracking? Eugene Houdry discovered in the 1920’s that heavy petroleum fractions crack over a solid catalyst, acid-treated natural clay, to lighter molecules. While clays and aluminas are still important ingredients of cracking catalyst, it was the introduction of zeolites by the Socony-Vacuum Oil Company in 1961 (2) which revolutionized catalytic cracking. The FCC process upgrades a variety of heavy feedstocks to lighter products (Figure 1). Typical Yields Figure 1. The FCC Process The cycle oils can be used as heavy fuels or, upon further upgrading, as distillate fuels. FCC conversion is usually defined as the yield of hydrocarbon products other than cycle oils. FCC naphtha is used as a gasoline blending component upon further treating. The gaseous components are upgraded to gasoline blending components in a variety of light ends upgrading processes such as acid alkylation, etherification, and polymerization. Light olefins, such as propene and ethene, can also be used as petrochemical feedstocks. 3 Today’s FCC catalysts (Figure 2) have grown increasingly complex and they catalyze a variety of desired reactions. The main components (Y zeolite, and active aluminas) catalyze a complex set of cracking reactions, starting with carbenium ion chemistry. Figure 2. FCC Catalyst Particle FCC catalyst is usually a porous microsphere (about 50% pore volume) which is spray-dried to a powder with a particle size distribution of 10 to 120 microns, with a particle density of about 1,400 kg/m3. The heart of the cracking catalyst is the Y zeolite (Figure 3) available in many derivatives of varying physical and chemical properties.
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