Catalysis [Splst Period'l Rpt Vol 07] PDF
Preview Catalysis [Splst Period'l Rpt Vol 07]
Catalysis Volume 7 A Specialist Periodical Report Catalysis Volume 7 A Review of the Recent Literature Published up to end-I 983 Senior Reporters G. C. Bond, Department of Chemistry, Brunel University, Uxbridge G. Webb, Department of Chemistry, University of Glasgow Reporters R. Burch, University of Reading A. D. H. Clague, Thornton Research Centre, Chester P. J. Gellings, Twente University of Technology, Enschede, The Netherlands M. J. Ledoux, Universite Louis Pasteur de Strasbourg, France J. R. H. Ross, Twente University of Technology, Enschede, The Netherlands C. J. Wright, Atomic Energy Research Establishment, Harwell The Royal Society of Chemistry Burlington House, London W I V OBN ISBN 0-851 86-58 4-4 ISSN 0140-0568 Copyright 0 1985 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 Unfortunately this is likely to be the last volume in this series to appear in the present format. In common with many other titles in the Specialist Periodical Reports, the Catalysis series has not sold in sufficient numbers to recover its cost and its future is therefore in jeopardy. One possibility currently receiving consideration is to produce future volumes in camera-ready form, which is a considerably cheaper method of production than typesetting. Indeed Volume 8 will be produced in this way, but at the moment the future thereafter is uncertain. In the present volume your Senior Reporters offer a blend of material, hoping that each reader will find something of especial interest. Professor Julian Ross contributes a valuable article on methanation and steam re- forming; this covers not only basic aspects of kinetics and mechanism, but also some of the practical scenarios for the large-scale applications of these processes. The second article, by Dr. Chris Wright, is concerned with useful- ness of neutron spectroscopy in the characterisation of catalysts. This tech- nique is especially sensitive to hydrogen, and the results of studies of hydro- gen in Raney nickel and many other systems are covered in this article. The third contribution deals with another quite new technique, and one which like neutron diffraction requires a large capital outlay. Dr. Derek Clague presents a timely introduction to the n.m.r. of solid state, clearly spelling out the very great advantages which the method offers for identification of solid phases. Professor Paul Gellings’ article on oxidation catalysts containing vanadium drives home the importance of this element as a component of catalysts having practical utility, with considerable potential for expansion as interest in the elimination of gaseous industrial effluents grows. Dr. Marc-Jacques Ledoux also breaks new ground with an important review of hydrodenitro- genation. It is not an easy system in which to get precise or reproducible results, but Dr. Ledoux performs a considerable service in rendering the far- flung technical literature into a shape which the more basically inclined can readily understand and appreciate. Finally Dr. Robbie Burch continues his valuable contribution to the review of progress, still rapid, in our under- standing of the structure and catalytic properties of supported metals. The senior of your Senior Reporters recalls with clarity the carelessness based on ignorance with which we threw together the components of the catalyst 35 years ago; the junior of your Senior Reporters started his research some ten years later, but we can both marvel at the extent to which our ability to analyse the structure of supported metal catalysts has progressed over this period. Progress is perhaps more easily seen in the refinement of the questions V vi we can ask rather than in the precision of the answers we can get: it is the discrepancy between the two that drives us ever forward. We trust it will be possible to continue this series beyond the next volume. Those who share this sentiment should (a) purchase this book, not simply read it in the Library, and (b) bombard the Officers of the Society with their views. G. C. Bond G. Webb Contents Chapter 1 Metal Catalysed Methanation and Steam Reforming By J. R. H. Ross 1 Introduction 1 2 The Processes 2 Steam Reforming 2 High-t emperature Steam Ref0 rming 2 Low-temperature Steam Reforming 5 Methanation of Coal-derived Synthesis Gas 6 The Adam and Eve (NFE) Project 8 The Cothane Process 11 Steam Dealkylation 12 Steam Reforming of Methanol 12 3 The Catalysts 13 Nickel Catalysts for Steam Reforming and Methanation 14 Coprecipitated Ni-A1203 Catalysts 14 Promotion of Cop r ecipit at ed Ni- A1 0 Catalysts 23 Materials with High-temperature Stability 25 Other Commercial Catalyst Formulations 28 Sulphur-resistant Catalysts 32 Other Investigations of Nickel Catalysts 35 The Use of other Metals for Methanation and Steam Reforming 36 Ruthenium 36 Rhodium 37 Other Metals 38 Catalysts for Steam Dealkylation 39 4 Some Mechanistic Aspects of the Methanation and Steam Reforming React ions 39 Met hanat ion 40 Steam Reforming of Methane and Higher Hydrocarbons 45 Chapter 2 Catalyst Characterization with Neutron Techniques By C. J. Wright 1 Introduction 46 2 Characterization of the Surfaces of Catalysts 46 Measurements of the Density of Surface Faces for High Surface Area Supports 46 vii viii Measurements of the Concentration of Surface Sites on High Surface Area Metal Catalysts 48 3 Characterization of the Bulk Properties of Catalysts 62 Measurements of Par ticle-size Distribution Functions of Supported Catalysts 62 Measurements of Crystallite Disorder in Catalysts 63 Measurements of Crystal Structures 68 (a) Zeolites 68 (b) Molecular Complexes 69 Determination of the Structure of Catalyst Supports by Spectroscopy with Particular Reference to Spillover and Hydrogen Diffusion 69 4 Characterization of Adsorbent-Adsorbate Interactions 72 Adsorbate Perturbation and Adsorbent -Adsorbate Bonding Studies by Inelastic Scattering 72 Chapter 3 High Resolution Solid State N.M.R. - Theory and Applications By A. D.I 3 Clague 1 Introduction 75 2 N.M.R. Parameters 76 The Larmor Frequency 76 The Chemical Shift 76 The Knight Shift 77 Coupling Constants 77 Signal Intensities 77 Relaxation Times 77 3 Problems with Solids 78 Low Sensitivity 78 Broad Lines 78 Dipolar Interact ion 78 Chemical Shift Anisotropy 79 Quadrupolar Interactions 80 Paramagnetic Interactions 80 Long Relaxation Times 81 Improving Sensitivity 81 Sample Size 81 Magnetic Field 82 Computers 82 Isotope Enrichment 82 Narrowing the Lines 82 Magic-angle Spinning 82 Variable-angle Sample Spinning 85
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