Theoretical Aspects of Heterogeneous Catalysis

547 Pages·1990·13.226 MB·English

by  John B. Moffat Ph.D. (auth.)

THEORETICAL ASPECTS
OF HETEROGENEOUS
CATALYSIS
VAN NOSTRAND REINHOLD
CATALYSIS SERIES
Burtron Davis, Series Editor
Metal-Support Interactions in Catalysis, Sintering, and Redispersion, edited by
Scott A. Stevenson, R.T.K. Baker, J.A. Dumesic, and Eli Ruckenstein
Molecular Sieves: Principles of Synthesis and Identification, R. Szostak
Raman Spectroscopy for Catalysis, John M. Stencel
Theoretical Aspects of Heterogeneous Catalysis, John B. Moffat
Biocatalysis, edited by Daniel A. Abramowicz
THEORETICAL ASPECTS
OF HETEROGENEOUS
CATALYSIS
John B. Moffat
Van Nostrand Reinhold Catalysis Series
~ VAN NOSTRAND REINHOLD
~ ____ New York
Copyright © 1990 by Van Nostrand Reinhold
Softcover reprint of the hardcover 1st edition 1990
Library of Congress Catalog Card Number H9-75H19
ISBN 978-94-010-9884-7 ISBN 978-94-010-9882-3 (eBook)
DOI 10.1007/978-94-010-9882-3
All rights reserved. No part of this work covered by the copyright hereon may be repro
duced or used in any form or by any means-graphic. electronic, or mechanical, includ
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without written permission of the publisher.
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Library of Congress Cataloging-in-Publication Data
Theoretical aspects of heterogeneous catalysis I John B. Moffat
leditor].
p. cm. - (Van Nostrand Reinhold catalysis series)
1. Heterogeneous catalysis. I. Moffat, John B. II. Series.
QD505.T47 1990 H9-75819
541.3 '95--dc20 CIP
Contents
Series Introduction IX
Preface XI
Contributors xiii
1 A Theoretical View and Approach to the Physics and
Chemistry of Zeolites and Molecular Sieves 1
E.G. Derouane, 1.M. Andre, L. Leherte, P. Galet,
D. Vanderueken, D.P. Vercallteren, and 1.G. Fripiat
Introduction
Quantum Mechanical Description of AI-Site-Related Proper-
ties in Zeolites 2
Statistical Mechanics and Molecular Dynamics Simulations
Applied to a Water-Ferrierite System 22
2 Conceptual Background for the Conversion of Hydrocarbons
on Heterogeneous Acid Catalysts 52
1.A. Martens and P.A. Jacobs
Introduction 52
Nomenclature and Representation of Alkylcarbenium and
Alkylcarbonium Ions Relevant to Alkane Conversion 53
Relative Stabilities of Alkylcarbenium and Alkylcarbonium
Ions 56
Rearrangements of Acyclic Alkylcarbenium Ions in Super-
acids 57
Alkylcarbenium Ions on the Surface of Heterogeneous Cata-
lysts 66
Carbocation Chemistry and Bifunctional Conversion of
Short-Chain Alkanes 70
Carbocation Chemistry and Bifunctional Conversion of
Long-Chain Alkanes 71
General Conclusions 106
v
vi CONTENTS
3 The Role of Next Nearest Neighbors in Zeolite Acidity and
Activity 110
William A. Wachter
Introduction 110
The Aluminosilicate Active Site III
Buffered Behavior and Zeolite Structure 112
Stability Criteria and the Next-Nearest-Neighbor Model 126
Paraffin Cracking Activity 127
Cumene Cracking Activity 130
Summary and Conclusions 130
4 Electronegativity Equalization, Solid-State Chemistry, and
Molecular Interactions 135
W.J. Mortier
Introduction 135
Electronegativity of an Atom in a Molecule 136
Explicit Expression for the Effective Electronegativity 139
The Electronegativity Equalization Method (EEM) 139
The Solid State 140
Molecular Interactions 141
Framework: Intrinsic Properties 142
Framework: Molecular Interactions 146
Br¢nsted Acidity: Intrinsic Properties ISO
Br¢nsted Acidity: Molecular Interactions 153
The Active Site 155
5 Quantum-Chemical Studies of Zeolites 160
Stanislau Beran
Introduction 160
Zeolite Models and Quantum-Chemical Methods 161
Zeolite Properties 168
Interaction of Zeolite Sites with Molecules 188
Conclusions 199
6 Theoretical Studies of Transition Metal Sulfide
Hydrodesulfurization Catalysts 206
Suzanne Harris and R.R. Chianelli
Introduction 206
Periodic Trends in the HDS Activity of Simple TMS 208
Promoted TMS Catalysts 214
Electronic Structure of the Simple and Promoted TMS 219
Structural Effects in Layered TMS 234
CONTENTS vii
Active Site Theory 241
Conclusions 252
7 Factors Affecting the Reactivity of Organic Model
Compounds in Hydrotreating Reactions 256
Claude Moreau and Patrick Geneste
Introduction 256
General Features 257
Reactivity of Aromatic Molecules 265
Reactivity of Saturated Molecules 294
Theoretical Modeling of the Reactivity 301
Conclusions 306
8 Theoretical Investigation of Metal-Support Interactions and
Their Influence on Chemisorption 311
Helmut Haberlandt
Introduction 311
Experimental Investigations of Geometric Structures and
Electronic Properties of Metal-Support Systems: Support
Influence on Adsorbates 317
The Support Influence on Chemisorption 323
Surface Modeling and Computational Methods 335
Metal-Support Interfaces and Support Influence on Chemi-
sorption: Recent Theoretical Results 345
Conclusions 379
Note Added in Proof 382
9 Mechanisms and Intermediates of Metal Surface Reactions:
Bond-Order Conservation Viewpoint 399
Eugeny Shustorouich
Introduction 399
The BOC-MP Model of Chemisorption 400
Mapping of Surface Reactions 415
Concluding Remarks 426
10 Structure and Electronic Factors in Heterogeneous Catalysis:
C=c, C=O, and C-H Activation Processes on Metals and
Oxides 431
Alfred B. Anderson
Atom Superposition and Electron Delocalization Molecular
Orbital (ASED-MO) Approach 433
Studies in Bond Activation 437
viii CONTENTS
Acetylene Bonding to Transition Metals: Structure and
Electronic Effects 437
CO Binding to Transition Metal Surfaces: A New Interac-
tion 442
CO Binding to ZnO and Surface Ion Relaxations 44b
CH Activation in Alkanes and Alkenes 448
Conclusions 454
11 Application of Band-Structure Calculations to Chemisorption 458
R.C. Baetzold
Introduction 458
Method of Calculation 459
Atomic Adsorbates 466
Molecular Stereochemistry 471
CO Adsorption 476
Saturated Hydrocarbons 480
Ethylene Adsorption 490
Chemisorbed Butadiene 494
Concluding Remarks 502
12 Quantum-Chemical Studies of the Acidity and Basicity of
Alumina 506
Satohiro Yoshida
Introduction 506
Acid-Base Properties of '}I-Alumina 508
Structure of Acidic and Basic Sites 509
Models for Molecular Orbital Calculations of Alumina 512
Types of Surface Hydroxyls 514
Brfllnsted Acidity 517
Basicity 521
Lewis Acidity 523
Conclusions 527
Index 531
Series Introduction
Catalysis involves just about every field of scientific study. This means
that a multidisciplinary approach is needed in catalytic studies. Catalysis
involves breaking and forming new bonds and this requires an under
standing of either adsorption by bonding to an extended structures or
bonding in a coordination sphere. Any understanding of catalytic action
must necessarily involve an understanding of this bonding.
Even 200 years ago scientists were aware that a properly treated mate
rial, such as charcoal, could adsorb an enormous quantity of gas. In 1812,
de Sassasure (English translation, Annal Philosphy, 6, 241 (1815» pro
posed that the ability of a material to increase the rate of chemical reac
tion was due to adsorption of the material in the fine structure of the solid
so that the concentrations of the reactants were significantly increased,
and this increase in concentration led to an increase in reaction rate.
During the 1800s, little advance was made in the understanding of adsorp
tion.
Sabatier (Bull. Soc. Chim. France, 6, 1261 (1939» must be among the
first to utilize chemisorption concepts in catalysis research. He, recalls,
"Like my illustrious master, Marcellin Berthelot, I always assumed that
the fundamental cause of all types of catalysis is the formation of J. tempo
rary and very rapid [chemical] combination of one of the reactants with a
body called the catalyst. . .. I have tenaciously held to my theory of a
temporary combination. It has guided my work both in hydrogenations
and in dehydrations." And a good guide it was since he was awarded the
Nobel Prize in 1912 for his work in catalysis. This award was followed
three years later when Ostwald was awarded the Nobel Prize for his work
in catalysis and provided an unprecedented period for catalysis.
Langmuir (1. Am. Chern. Soc., 38,2221 (1916» advanced his views of
adsorption in the 1910s. His model was simple: an atom, such as formed
by the dissociation of hydrogen, was confined to the space occupied by a
surface atom of the adsorbent. Thus, Langmuir advanced his famous
checkerboard model; the squares of the board represented the space as
signed to each surface atom and the checker piece represented the indi
vidual adsorbed atom held to its space by a chemical bond. Langmuir
(Trans. Faraday Soc., 17, 621 (1921) developed very successful kinetic
equations based upon his adsorption model. In 1932 he was awarded the
ix
x SERIES INTRODUCTION
Nobel Prize for his work on adsorption so that his views had great popu
larity. However, some held the view that adsorption involved multilayers
rather than the monolayer as required by Langmuir's theory. Sir Hugh
Taylor complicated the situation even more by advancing his views of
activated adsorption. Gradually, the scientific community realized that
there was not a simple model that was adequate to describe the totality of
adsorption just as the advances of quantum mechanics led the community
to realize that there is not just one simple description of chemical bonds.
The application of quantum mechanics to provide a description of ad
sorption on catalytic surfaces was slow to materialize. Thus, it was not
until 1950 that a very influential and, by today's standards, rather elemen
tary paper appeared that attempted to bring together the theoretical ideas
of the solid state, adsorption, and catalytic reactions. While several pa
pers appeared at about the same time, Dowden's paper (1. Chern. Soc.,
1950, 242) appears to have had the major impact. And just as it was the
ability of Langmuir to present complex theoretical ideas in terms of sim
ple models that were understandable to working catalytic scientists, so it
was with Dowden and his electronic views of catalysis. But simple models
that are able to bridge the gap between the world of complex mathemati
cal equations and the art of the practicing catalytil: scientist have been
slow to emerge. In the nearly 40 years since Dowden first advanced his
ideas, tremendous advances have occurred in the theories of chemical
bonding, the physics of the solid state, and the dynamics of chemical
reactions. There is a need to reduce this mass of sophisticated mathemati
cal material to models that can guide catalytic scientists. It is intended
that this book will provide a step in that direction.
Burtron H. Davis