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Preface xiii List of Acronyms xvii 1 Introduction to Catalysis 1
1.1 What Is Catalysis? 2
1.2 Catalysts Can Be Atoms,Molecules, Enzymes, and Solid Surfaces 4
1.2.1 Homogeneous Catalysis 5
1.2.2 Biocatalysis 5
1.2.3 Heterogeneous Catalysis 6
1.3 Why Is Catalysis Important? 9
1.3.1 Catalysis and Green Chemistry 9
1.3.2 Atom Efficiency, E Factors, and Environmental Friendliness 10
1.3.3 The Chemical Industry 11
1.4 Catalysis as a Multidisciplinary Science 16
1.4.1 The Many Length Scales of a "Catalyst" 16
1.4.2 Time Scales in Catalysis 17
1.5 The Scope of this Book 18
1.6 Appendix: Catalysis in Journals 18 References 22 2 Kinetics 23
2.1 Introduction 23
2.2 The Rate Equation and Power Rate Laws 25
2.3 Reactions and Thermodynamic Equilibrium 28
2.3.1 Example of Chemical Equilibrium: The Ammonia Synthesis 31
2.3.2 Chemical Equilibrium for a Nonideal Gas 33
2.4 The Temperature Dependence of the Rate 35
2.5 Integrated Rate Equations: Time Dependence of Concentrations in Reactions of Different Orders 38
2.6 Coupled Reactions in Flow Reactors: The Steady State Approximation 41
2.7 Coupled Reactions in Batch Reactors 45
2.8 Catalytic Reactions 48
2.8.1 The Mean-Field Approximation 52
2.9 Langmuir Adsorption Isotherms 53
2.9.1 Associative Adsorption 53
2.9.2 Dissociative Adsorption 54
2.9.3 Competitive Adsorption 55
2.10 Reaction Mechanisms 55
2.10.1 Langmuir-Hinshelwood or Eley-Rideal Mechanisms 56
2.10.2 Langmuir-Hinshelwood Kinetics 56
2.10.3 The Complete Solution 57
2.10.4 The Steady State Approximation 58
2.10.5 The Quasi-Equilibrium Approximation 59
2.10.6 Steps with Similar Rates 60
2.10.7 Irreversible Step Approximation 61
2.10.8 TheMARI Approximation 61
2.10.9 The Nearly Empty Surface 62
2.10.10 The Reaction Order 63
2.10.11 The Apparent Activation Energy 63
2.11 Entropy, Entropy Production, Auto Catalysis, and Oscillating Reactions 67
2.12 Kinetics of Enzyme-Catalyzed Reactions 73 References 77 3 Reaction Rate Theory 79
3.1 Introduction 79
3.2 The Boltzmann Distribution and the Partition Function 80
3.3 Partition Functions of Atoms andMolecules 83
3.3.1 The Boltzmann Distribution 83
3.3.2 Maxwell-Boltzmann Distribution of Velocities 86
3.3.3 Total Partition Function of a System 87
3.4 Molecules in Equilibrium 93
3.5 Collision Theory 100
3.5.1 Reaction Probability 104
3.5.2 Fundamental Objection against Collision Theory 105
3.6 Activation of Reacting Molecules by Collisions: The Lindemann Theory 106
3.7 Transition State Theory 107
3.8 Transition State Theory of Surface Reactions 113
3.8.1 Adsorption of Atoms 113
3.8.2 Adsorption ofMolecules 118
3.8.3 Reaction between Adsorbates 121
3.8.4 Desorption ofMolecules 123
3.9 Summary 124 References 127 4 Catalyst Characterization 129
4.1 Introduction 129
4.2 X-ray Diffraction (XRD) 131
4.3 X-ray Photoelectron Spectroscopy (XPS) 134
4.4 X-ray Absorption Spectroscopy (EXAFS and XANES) 139
4.4.1 Extended X-ray Absorption Fine Structure (EXAFS) 139
4.4.2 X-ray Absorption Near-Edge Spectroscopy (XANES) 143
4.5 Electron Microscopy 144
4.6 Mossbauer Spectroscopy 148
4.7 Ion Spectroscopy: SIMS, LEIS, RBS 151
4.8 Temperature-Programmed Reduction, Oxidation, and Sulfidation 155
4.9 Infrared Spectroscopy 158
4.10 Surface Science Techniques 160
4.10.1 Low Electron Energy Diffraction (LEED) 161
4.10.2 Scanning ProbeMicroscopy 164
4.11 Concluding Remarks 169 References 170 5 SolidCatalysts 173
5.1 Requirements of a Successful Catalyst 173
5.2 The Structure ofMetals, Oxides, and Sulfides and Their Surfaces 175
5.2.1 Metal Structures 175
5.2.2 Surface Crystallography of Metals 176
5.2.3 Oxides and Sulfides 182
5.2.4 Surface Free Energy 185
5.3 Characteristics of Small Particles and Porous Material 187
5.3.1 The Wulff Construction 187
5.3.2 The Pore System 190
5.3.3 The Surface Area 191
5.4 Catalyst Supports 197
5.4.1 Silica 197
5.4.2 Alumina 199
5.4.3 Carbon 201
5.4.4 Shaping of Catalyst Supports 201
5.5 Preparation of Supported Catalysts 203
5.5.1 Coprecipitation 203
5.5.2 Impregnation, Adsorption, and Ion Exchange 203
5.5.3 Deposition Precipitation 205
5.6 Unsupported Catalysts 206
5.7 Zeolites 206
5.7.1 Structure of a Zeolite 207
5.7.2 Compensating Cations and Acidity 208
5.7.3 Applications of Zeolites 209
5.8 Catalyst Testing 210
5.8.1 Ten Commandments for Testing Catalysts 211
5.8.2 Activity Measurements 213 References 223 6 Surface Reactivity 225
6.1 Introduction 225
6.2 Physisorption 226
6.2.1 The Van derWaals Interaction 226
6.2.2 Including the Repulsive
Part 227
6.3 Chemical Bonding 228
6.3.1 Bonding in Molecules 229
6.3.2 The Solid Surface 233
6.4 Chemisorption 246
6.4.1 The Newns-Anderson Model 246
6.4.2 Summary of the Newns-Anderson Approximation in Qualitative Terms 252
6.4.3 Electrostatic Effects in Atomic Adsorbates on Jellium 254
6.5 Important Trends in Surface Reactivity 256
6.5.1 Trend in Atomic Chemisorption Energies 257
6.5.2 Trends in Molecular Chemisorption 261
6.5.3 Trends in Surface Reactivity 265
6.5.4 Universality in Heterogeneous Catalysis 274
6.5.5 Scaling Relations 276
6.5.6 Appendix: Density Functional Theory (DFT) 278 References 280 7 Kinetics of Reactions on Surfaces 283
7.1 Elementary Surface Reactions 283
7.1.1 Adsorption and Sticking 283
7.1.2 Desorption 289
7.1.3 Lateral Interactions in Surface Reactions 295
7.1.4 Dissociation Reactions on Surfaces 297
7.1.5 Intermediates in Surface Reactions 301
7.1.6 Association Reactions 301
7.2 Kinetic Parameters from Fitting Langmuir-Hinshelwood Models 304
7.3 Microkinetic Modeling 306
7.3.1 Reaction Scheme and Rate Expressions 307
7.3.2 Activation Energy and Reaction Orders 310
7.3.3 Ammonia Synthesis Catalyst underWorking Conditions 313 References 315 8 Catalysis in Practice: Synthesis Gas and Hydrogen 319
8.1 Introduction 319
8.2 Synthesis Gas and Hydrogen 319
8.2.1 Steam Reforming: Basic Concepts of the Process 321
8.2.2 Mechanistic Detail of Steam Reforming 323
8.2.3 Challenges in the Steam Reforming Process 326
8.2.4 The SPARG Process: Selective Poisoning by Sulfur 328
8.2.5 Gold-Nickel Alloy Catalyst for Steam Reforming 329
8.2.6 Direct Uses of Methane 330
8.3 Reaction of Synthesis Gas 332
8.3.1 Methanol Synthesis 332
8.3.2 Fischer-Tropsch Process 343
8.4 Water-Gas Shift Reaction 351
8.5 Synthesis of Ammonia 353
8.5.1 History of Ammonia Synthesis 353
8.5.2 Ammonia Synthesis Plant 355
8.5.3 Operating the Reactor 356
8.5.4 Scientific Rationale for Improving Catalysts 359
8.6 Promoters and Inhibitors 361
8.7 The "Hydrogen Society" 364
8.7.1 The Need for Sustainable Energy 364
8.7.2 Sustainable Energy Sources 366
8.7.3 Energy Storage 368
8.7.4 Hydrogen Fuel Cells 377 References 385 9 Oil Refining and Petrochemistry 391
9.1 Crude Oil 391
9.2 Hydrotreating 394
9.2.1 Heteroatoms and Undesired Compounds 395
9.2.2 Hydrotreating Catalysts 397
9.2.3 Hydrodesulfurization Reaction Mechanisms 399
9.3 Gasoline Production 402
9.3.1 Fluidized Catalytic Cracking 404
9.3.2 Reforming and Bifunctional Catalysis 406
9.3.3 Alkylation 410
9.4 Petrochemistry: Reactions of Small Olefins 412
9.4.1 Ethylene Epoxidation 412
9.4.2 Partial Oxidation and Ammoxidation of Propylene 413
9.4.3 Polymerization Catalysis 415 References 418 10 Environmental Catalysis 421
10.1 Introduction 421
10.2 Air Pollution by Automotive Exhaust 422
10.2.1 The Three-Way Catalyst 423
10.2.2 Catalytic Reactions in the Three-Way Catalyst: Mechanism and Kinetics 429
10.2.3 Concluding Remarks on Automotive Catalysts 436
10.3 Air Pollution by Large Stationary Sources 437
10.3.1 Selective Catalytic Reduction: The SCR Process 437
10.3.2 The SCR Process for Mobile Units 443 References 444 Appendix 447 Questions and Exercises 449 Index 497