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CataIysis Volume 6 A Review of the Recent Literature Pub to mid-1982 PDF

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Cata Iy s is Volume 6 A Specialist Periodical Report Cat aI y si s Volume 6 A Review of the Recent Literature Pub ished up to mid-1982 Senior Reporters G. C. Bond, Department of Chemistry, Brunei University, Uxbridge G. Webb, Department of Chemistry, University of Glasgow Reporters G. F. Berndt, Edinburgh School of Agriculture M. D. Birkett, Council for Mineral Technology, Randburg, South Africa R. Burch, University of Reading E. Garrone, lstituto di Chimica-Fisica, Torino, Italy M. Goodman, University of Cambridge E. Guglielminotti, lstituto di Chimica-F isica, Torino, Italy C. N. Kenney, University of Cambridge A. T. Kuhn, Eastman Dental Hospital, London W. Morton, University of Cambridge D. Mukesh, University of Cambridge B. A. Murrer, Johnson Matthey Research Centre, Reading E . K. Poels, Rijksuniversiteit Leiden, The Netherlands V. Ponec, Rijksuniversiteit Leiden, The Netherlands M. J. H. Russell, Johnson Matthey' Research Centre, Reading A. Zecchina, lstituto di Chimica-Fisica, Torino, Italy The Royal Society of Chemistry Burlington House, London WlV OBN ISBN 0-85 186-5 74-7 ISSN 01404568 Copyright 0 1983 The Royal Society of Chemistry All Rights Reserved No part of this book may be reproduced or transmitted in any form or by any means - graphic, electronic, including photocopying, recording, taping or information storage and retrieval systems - without written permission from the Royal Society of Chemistry Printed in Great Britain at the Alden Press, Oxford. London and Northampton. Preface The recession which has hit to some degree almost every sector of manu- facturing industries in the Western World has not left the chemical industry unscathed, but it has understandably led to a resurgence of interest in the phenomenon of catalysis. It is appreciated that new and better catalysts can reduce the energy input into chemical processes, improve product yields, minimise by-products, and hence lead to decreased process costs. The associated energy crisis, and the geopolitical vulnerability of much of our crude oil supply, have focused attention on alternative raw materials for the petrochemicals industry, and for liquid fuels. The scope for innovative catalysis in this area is without limit, and the contents of the present volume reflect these potentialities. We have tried once again to obtain reviews of different character and style, mirroring current interests and emphases, covering applications and funda- mentals as well as investigational methods. We have also tried to bring day- light into one or two areas where it is badly needed: in other areas we have to be content with descriptions of the darkness before the dawn. One of the more curious observations in a field where the curious is the norm is that the rates of certain oxidation reactions can oscillate. Nigel Kenney and his colleagues review the experimental findings and their inter- pretation, but it is difficult to avoid the impression that experimentalists and theoreticians speak different languages which are not mutually understood. An Esperanto of oscillatory systems seems to be needed. Robbie Burch and one of us have endeavoured to bring some sense of order into the subject of metal-support interactions. The discovery by scientists in the Exxon Laboratory that titania and other oxides when used as supports have the property of much decreasing the extent of chemi- sorption on the supported metal after high temperature reduction has stimu- lated research in support effects in general, and it is our conviction that there is promise, so far unfulfilled, of so composing supported metal catalysts as to increase their effectiveness greatly. We believe that the occurrence of spillover catalysis and bifunctional catalysis will be recognised as being more important and more common than has hitherto been suspected. It has long been appreciated that there is a close connection between catalysis and electrochemistry, although the exact nature of the connection is somewhat difficult to specify. Anselm Kuhn, M. Birkett and one of your Senior Reporters have attempted to explore the origins of the similarities and the differences between the two, and suggest that this frontier zone is worthy of more detailed investigation than it has received in the past. We hope that this article may awaken some interest in the subject. vi Preface The use of conventional optical spectroscopic methods for the structural characterisation of surface adsorbed species and surface sites has been a grow- ing area of interest during the past few years and is the subject of the review by A. Zecchina, E. Garrone and E. Guglielminotti. The reviewers consider the adsorption of a variety of species on supported transition metal ions, pure oxides and zeolites and dispersed metals. Their critical treatment of the subject highlights the power of spectroscopic techniques in providing direct information regarding the chemical nature and identity of adsorbed species and of surface adsorption sites. Our coverage of investigational methods is continued by Gwendoline Berndt, who reviews the use of radiotracers in the study of surface catalysed processes, with particular reference to more recent developments in experi- mental methods. The use of this approach to study both adsorption processes and mechanisms of reactions is well illustrated in this chapter. We try to include at least one review in each Report on some aspect of homogeneous catalysis. One of the most successful applications has been in the area of hydroformylation and we are grateful to Mike Russell and Barry Murrer for writing a comprehensive and clear account of recent achievements. We are most grateful to Vladimir Pon6c for again contributing a major article, this time on the subject of the production of oxygenated species from synthesis gas. He produced this, with his colleague E. K. Poels, at very short notice after another author had informed us late in the day that he was unable to complete his commission. The article is scholarly, informative and interesting, and demonstrates how wide a knowledge of chemistry is needed for the study of catalytic phenomena. In the Preface to the last volume we asked for comments and criticism from our readers on the choice of subject matter: we have received none, from which we conclude either that everyone is satisfied or that nobody reads the Preface. We repeat the invitation. The problem of devising a balanced selection of articles of wide interest is not an easy one, and we would welcome some help. Your ideas would receive our careful consider- ation. G. C. Bond G. Webb Cont ents Chapter 1 Oscillatory Phenomena in Heterogeneous Catalysed Oxidation Reactions 1 By D. Mukesh, M. Goodman, C. N. Kenney, and W. Morton 1 Introduction 1 2 CO Oxidation 1 3 H2 Oxidation 2 4 Hydrocarbon Oxidation 3 5 NH3 Oxidation 3 6 Oxidation of CO/H2 or CO/Hydrocarbon Mixtures 3 7 Forced Periodic Oscillations 4 8 Steady State and Dynamic Models 8 9 Modelling of Oscillations in CO Oxidation 11 10 Modelling of CO Oxidation 13 11 Formation of Buffer Species 16 12 Oxidation of CO/But-lene Mixtures 18 13 Effect of Parameters and Operating Conditions 19 14 Conclusions 23 15 List of Symbols 24 Chapter 2 Strong Metal-Support I nteractions 27 By G. C. Bond and R. Burch 1 Real and Apparent Metal-Support Interactions 27 Particle Size Effects 27 Early Evidence for Support Effects 28 Bifunctional Catalysis 28 29 Catalyst Poisons Promoters 29 Real Metal-Support Interactions 30 viii Cont ents 2 Apparent Metal-Support Effects 32 Specific Particle Size Effects 32 Bifunctional and Spillover Catalysis 33 3 Metal-Support Interactions with Insulator Oxides 35 Interactions with Simple Insulator Oxides 35 Interactions in Zeolites 37 4 Metal-Support Interactions with Transition-metal Oxides (TMO): Evidence from Chemisorption Studies 37 Chemisorption of H2 and CO 38 Platinum Metals on Ti02 38 Absorption of H2 by Ti02-supported Pd 41 Fe, Co, and Ni on Ti02 42 Other Supports 43 Adsorption of O2a nd H2/02T itrations 45 N2 Adsorption 46 5 Structural Information on TMO-supported Catalysts 46 X-Ray Measurements 46 Transmission Electron Microscopy (TEM) 47 6 Influence of SMSI on Catalytic Properties 48 Structure-insensitive Reactions 48 Structure-sensitive Reactions 49 Hydr oge noly sis 49 CO/H2 Reactions 51 NH3 Synthesis Reaction 54 7 Evidence Concerning the Origin and Nature of SMSI 54 Reducibility of the Support 54 Extent of Electron Transfer between the Support and the Metal 56 Infrared Spectra of Adsorbed Molecules 57 8 Conclusions 58 Chapter 3 The Catalytic Hydrogenation of Organic Compounds - A Comparison between the G as-p h ase, Liqu id-ph ase, and E lec troch em ical Routes 61 By M. D. Birkett, A. T. Kuhn, and G. C. Bond 1 Introduction 61 2 Gas-phase and Electrochemical Catalysis 62 Similarities and Dissimilarities 62 Temperature Effects in Electrode Kinetics 64

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