CHAPTER 1 METALS AND ALLOYS
1.1 The Metallic State ......................................... 2
1.1.1 Characteristic Properties ........................... 2
1.1.2 Theories of the Metallic State ...................... 9
1.2 The Metallic Surface ...................................... 14
1.2.1 Methods of Preparation ............................. 14
1.2.2 Structure of Metallic Surfaces ..................... 16
1.2.3 Theoretical Descriptions of the Metal Surface ...... 22
1.3 Alloys .................................................... 24
1.3.1 The Formation of Alloys ............................ 24
1.3.2 Electronic Properties of Alloys and Theoretical
Models ............................................. 27
1.3.3 The Composition of Alloy Surfaces .................. 29
References ................................................ 31
CHAPTER 2 SMALL METAL PARTICLES AND SUPPORTED METAL
CATALYSTS
2.1 Introduction .............................................. 36
2.1.1 Microscopic Metals ................................. 36
2.1.2 Instability of Small Metal Particles ............... 38
2.2 Preparation of Unsupported Metal Particles ................ 39
2.3 Supported Metal Catalysts ................................. 40
2.3.1 Scope .............................................. 40
2.3.2 Methods of Preparation ............................. 41
2.4 Measurement of the Size and Shape of Small Metal
Particles ................................................. 47
2.4.1 Introduction: Sites, Models, and Size
Distributions ...................................... 47
2.4.2 Physical Methods for Characterising Small Metal
Particles .......................................... 52
2.4.3 Measurement of Dispersion by Selective Gas-
Chemisorption ...................................... 58
2.5 Properties of Small Metal Particles ....................... 60
2.5.1 Variation of Physical Properties with Size:
Introduction ....................................... 60
2.5.2 Structure .......................................... 63
2.5.3 Energetic Properties ............................... 65
2.5.4 Electronic Properties .............................. 66
2.5.5 Theoretical Methods ................................ 67
2.5.6 Conclusions ........................................ 68
2.6 Metal-Support Interactions ................................ 69
2.6.1 Causes and Mechanisms .............................. 69
2.6.2 Particle Size Effects and Metal-Support
Interactions: Summary .............................. 74
2.7 Promoters and Selective Poisons ........................... 75
2.8 Sintering and Redispersion ................................ 77
References ................................................ 78
CHAPTER 3 CHEMISORPTION AND REACTIONS OF HYDROGEN
3.1 The Interaction of Hydrogen with Metals ................... 94
3.2 Chemisorption of Hydrogen on Unsupported Metals and
Alloys .................................................... 97
3.2.1 Introduction ....................................... 97
3.2.2 The Process of Chemisorption ...................... 100
3.2.3 The Chemisorbed State: Geometric Aspects .......... 102
3.2.4 The Chemisorbed State: Energetic Aspects .......... 108
3.3 Chemisorption of Hydrogen on Supported Metals ............ 114
3.3.1 Introduction: Determination of Metal Dispersion ... 114
3.3.2 Characterisation of Chemisorbed Hydrogen .......... 124
3.3.3 Theoretical Approaches ............................ 129
3.3.4 Hydrogen Spillover ................................ 132
3.3.5 The "Strong Metal-Support Interaction" ............ 137
3.4 Reactions of Hydrogen .................................... 140
References ............................................... 142
CHAPTER 4 THE CHEMISORPTION OF HYDROCARBONS
4.1 Introduction ............................................. 154
4.1.1 Types of Alkane ................................... 154
4.1.2 Types of Unsaturated Hydrocarbon .................. 154
4.1.3 The Literature .................................... 155
4.2 The Chemisorption of Hydrocarbons: An Overview ........... 156
4.3 The Techniques ........................................... 158
4.4 Identification of Adsorbed Hydrocarbon Species ........... 161
4.4.1 The Catalogue - or 'The Organometallic Zoo' ....... 161
4.4.2 The π and di-σ Forms of Chemisorbed Alkenes ...... 169
4.5 Structures and Properties of Chemisorbed Hydrocarbons .... 176
4.5.1 Detailed Structures of Chemisorbed Alkenes ........ 176
4.5.2 Structures of Chemisorbed Ethyne .................. 178
4.5.3 Structures of Chemisorbed Benzene ................. 178
4.5.4 Heats of Adsorption ............................... 180
4.5.5 Characterisation by Other Spectroscopic Methods ... 186
4.5.6 C6 Molecules ...................................... 186
4.6 Thermal Decomposition of Chemisorbed Hydrocarbons ........ 186
4.7 Theoretical Approaches ................................... 190
4.8 Chemisorption of Alkanes ................................. 196
4.9 The Final Stage: Carbonaceous Deposits ................... 197
References ............................................... 198
CHAPTER 5 INTRODUCTION TO THE CATALYSIS OF HYDROCARBON
REACTIONS
5.1 The Essential Nature of Catalysis ........................ 210
5.1.1 A Brief History of Catalysis ...................... 210
5.1.2 How Catalysts Act ................................. 211
5.1.3 The Catalytic Cycle ............................... 213
5.2 The Formulation of Kinetic Expressions ................... 214
5.2.1 Mass Transport versus Kinetic Control ............. 214
5.2.2 The Purpose of Kinetic Measurements ............... 215
5.2.3 Measurement and Expression of Rates of Reaction ... 216
5.2.4 The Langmuir-Hinshelwood Formalism ................ 218
5.2.5 Effect of Temperature on Rate and Rate Constant ... 221
5.2.6 Selectivity ....................................... 223
5.2.7 Kinetic modelling ................................. 225
5.3 The Concept of Reaction Mechanism ........................ 227
5.4 The Idea of the Active Centre ............................ 229
5.5 The Use of Bimetallic Catalysts .......................... 234
5.6 The Phenomenon of 'Compensation' ......................... 239
5.7 The Temkin Equation: Assumptions and Implications ........ 246
5.8 Techniques ............................................... 247
5.8.1 Reactors .......................................... 247
5.8.2 Use of Stable and Radioactive Isotopes ............ 249
References ............................................... 251
CHAPTER 6 EXCHANGE OF ALKANES WITH DEUTERIUM
6.1 Introduction ............................................. 257
6.2 Equilibration of Linear and Branched Alkanes with
Deuterium ................................................ 260
6.2.1 Methane ........................................... 260
6.2.2 Ethane and Higher Linear Alkanes .................. 267
6.2.3 Higher Linear Alkanes ............................. 271
6.2.4 Branched Alkanes .................................. 273
6.3 Equilibration of Cycloalkanes with Deuterium ............. 275
6.4 Interalkane Exchange ..................................... 285
6.5 Conclusions .............................................. 285
References ............................................... 287
CHAPTER 7 HYDROGENATION OF ALKENES AND RELATED PROCESSES
7.1 Introduction ............................................. 292
7.2 Hydrogenation of Ethene and Propene ...................... 297
7.2.1 Kinetics of Hydrogenation ......................... 297
7.2.2 Structure Sensitivity ............................. 303
7.2.3 Ethene Hydrogenation on Bimetallic Catalysts ...... 306
7.2.4 Reactions of Ethene and of Propene with
Deuterium ......................................... 307
7.2.5 Reactions on Single Crystal Surfaces .............. 319
7.2.6 The Reaction Mechanism: Microkinetic Analysis,
Monte Carlo Simulation, and Multiple Steady
States ............................................ 321
7.2.7 Catalysis by Hydrogen Spillover and the
Reactivity of Hydrogen Bronzes .................... 325
7.3 Reactions of the Butenes with Hydrogen and with
Deuterium ................................................ 328
7.3.1 Then-Butenes ...................................... 328
7.3.2 The Single Turnover Approach ...................... 333
7.3.3 Isobutene ......................................... 334
7.3.4 Exchange Reactions between Alkenes ................ 335
7.4 Reactions of Higher Alkenes with Hydrogen and with
Deuterium ................................................ 336
7.5 Hydrogenation of Cycloalkenes ............................ 338
7.5.1 Cyclohexene ....................................... 338
7.5.2 Other Cycloalkenes ................................ 339
7.5.3 Substituted Cycloalkenes: Stereochemical
Factors ........................................... 340
References ............................................... 348
CHAPTER 8 HYDROGENATION OF ALKADIENES AND POLYENES
8.1 Introduction ............................................. 357
8.1.1 Types of Unsaturation ............................. 357
8.1.2 Practical Applications of Selective
Hydrogenation: Outline of Mechanisms .............. 359
8.2 Hydrogenation of 1,2-Alkadienes (Allenes) ................ 360
8.2.1 Hydrogenation of Propadiene ....................... 360
8.2.2 Hydrogenation of Substituted 1,2-Alkadienes ....... 362
8.2.3 Hydrogenation of Cumulenes ........................ 365
8.3 Hydrogenation of 1,3-Butadiene ........................... 365
8.3.1 General Characteristics of Butadiene
Hydrogenation ..................................... 365
8.3.2 Chemisorbed States of 1,3-Butadiene ............... 366
8.3.3 Hydrogenation of 1,3-Butadiene on Single Crystal
Surfaces .......................................... 367
8.3.4 Hydrogenation of 1,3-Butadiene on Supported
and Unsupported Metals ............................ 368
8.3.5 The Reaction of 1,3-Butadiene with Deuterium:
Reaction Mechanisms ............................... 375
8.3.6 Hydrogenation of 1,3-Butadiene by Bimetallic
Catalysts ......................................... 379
8.4 Hydrogenation of Higher Alkadienes ....................... 382
8.4.1 Linear Alkadienes ................................. 382
8.4.2 Branched Alkadienes ............................... 386
8.4.3 Cycloalkadienes ................................... 388
References ............................................... 390
CHAPTER 9 HYDROGENATION OF ALKYNES
9.1 Introduction ............................................. 395
9.1.1 The Scope of the Literature ....................... 395
9.1.2 Industrial Applications of Alkyne Hydrogenation ... 396
9.1.3 The Chemisorbed State of Alkynes .................. 397
9.1.4 The Origin of Selectivity in Alkyne
Hydrogenation ..................................... 398
9.1.5 Interpretation of Results: Some Preliminary
Comments .......................................... 399
9.2 Hydrogenation of Ethyne: 1, In Static Systems ............ 400
9.2.1 Introduction ...................................... 400
9.2.2 Kinetic Parameters ................................ 401
9.2.3 The Formation of Benzene from Ethyne .............. 407
9.2.4 The Reaction of Ethyne with Deuterium ............. 407
9.3 Hydrogenation of Ethyne: 2, in Dynamic System with
Added Ethene ............................................. 411
9.3.1 Kinetics and Selectivity .......................... 411
9.3.2 Mechanisms and Modelling .......................... 415
9.3.3 Oligomerisation ................................... 417
9.3.4 Gaseous Promoters ................................. 417
9.4 Use of Bimetallic Catalysts for Ethyne Hydrogenation ..... 418
9.5 Hydrogenation of Higher Alkynes .......................... 421
9.5.1 Propyne ........................................... 421
9.5.2 The Butynes ....................................... 422
9.5.3 Alkyl-Substituted Alkynes Having More Than Four
Carbon Atoms ...................................... 426
9.5.4 Aryl-Substituted Alkynes .......................... 428
9.5.5 Multiply-Unsaturated Molecules .................... 429
9.6 Conclusion ............................................... 430
References ............................................... 431
CHAPTER 10 HYDROGENATION OF THE AROMATIC RING
10.1 Introduction ............................................. 438
10.1.1 Scope ............................................. 438
10.1.2 Industrial Applications of Benzene
Hydrogenation ..................................... 439
10.2 Kinetics and Mechanism of Aromatic Ring Hydrogenation .... 440
10.2.1 Introduction: Early Work .......................... 440
10.2.2 Kinetics of Aromatic Ring Hydrogenation ........... 441
10.2.3 Rate Expressions and Reaction Mechanisms .......... 446
10.2.4 Temperature-Inversion of Rates .................... 448
10.2.5 Hydrogenation of Benzene Over Bimetallic
Catalysts ......................................... 450
10.2.6 Exchange of Aromatic Hydrocarbons with
Deuterium ......................................... 453
10.2.7 Hydrogenation of Benzene to Cyclohexene ........... 457
10.3 Hydrogenation of Alkyl-Substituted Benzenes .............. 458
10.3.1 Kinetic Parameters ................................ 458
10.3.2 Stereochemistry of the Hydrogenation of Alkyl-
Substituted Benzenes .............................. 460
10.4 Hydrogenation of Multiple Aromatic Ring Systems .......... 461
10.4.1 Polyphenyls ....................................... 461
10.4.2 Fused Aromatic Rings: (1) Naphthalene ............. 461
10.4.3 Fused Aromatic Rings: (2) Multiple Fused Rings .... 466
References ............................................... 468
CHAPTER 11 HYDROGENATION OF SMALL ALICYCLIC RINGS
11.1 Introduction ............................................. 473
11.2 Hydrogenation and Hydrogenolysis of Cyclopropane ......... 477
11.2.1 Kinetics .......................................... 477
11.2.2 The Reaction of Cyclopropane with Deuterium ....... 481
11.2.3 Reaction Mechanisms ............................... 482
11.3 Hydrogenation of Alkylcyclopropanes ...................... 484
11.3.1 Mono-alkylcyclopropanes ........................... 484
11.3.2 Poly-alkylcyclopropanes ........................... 488
11.3.3 The Cyclopropane Ring in More Complex
Hydrocarbons ...................................... 490
11.4 Hydrogenation of Cyclopropanes Having Other Unsaturated
Groups ................................................... 491
11.5 Hydrogenation of Alkylcyclobutanes and Related
Molecules ................................................ 494
References ............................................... 499
CHAPTER 12 DEHYDROGENATION OF ALKANES
12.1 Introduction ............................................. 501
12.2 Dehydrogenation of Acyclic Alkanes ....................... 504
12.2.1 Introduction: Alkane Chemisorption ................ 504
12.2.2 Supported Platinum and Platinum-Tin Catalysts ..... 505
12.2.3 Other Metals and Modifiers ........................ 507
12.2.4 Kinetics and Mechanism ............................ 508
12.3 Dehydrogenation of Cycloalkanes .......................... 509
12.3.1 Overview .......................................... 509
12.3.2 Reaction on Pure Metals ........................... 510
12.3.3 Reaction on Bimetallic Catalysts .................. 512
12.4 The Chemisorption of Hydrogen on Platinum ................ 514
12.5 The Formation, Structure, and Function of Carbonaceous
Deposits ................................................. 516
12.6 The Homologation of Methane .............................. 519
References ............................................... 520
CHAPTER 13 REACTIONS OF THE LOWER ALKANES WITH HYDROGEN
13.1 Introduction ............................................. 526
13.1.1 A Short Philosophical Digression .................. 526
13.1.2 Alkane Hydrogenolysis: General Characteristics .... 527
13.1.3 Problems in Studying Reaction Kinetics ............ 528
13.1.4 Ways of Expressing Product Composition ............ 530
13.2 Hydrogenolysis of the Lower Alkanes on Single Metal
Catalysts: Rates, Kinetics, and Mechanisms ............... 531
13.2.1 The Beginning ..................................... 531
13.2.2 Kinetic Parameters ................................ 531
13.2.3 Mechanisms and Kinetic Formulations ............... 540
13.2.4 A Generalised Model for Alkane Hydrogenolysis ..... 549
13.2.5 Alkane Hydrogenolysis on Metals Other than
Platinum .......................................... 552
13.3 Structure-Sensitivity of Rates of Alkane
Hydrogenolysis ........................................... 552
13.4 Selectivity of Product Formation in Alkane
Hydrogenolysis ........................................... 555
13.5 Mechanisms Based on Product Selectivities ................ 562
13.6 Hydrogenolysis of Alkanes on Ruthenium Catalysts ......... 565
13.7 Effects of Additives and the Strong Metal-Support
Interaction on Alkane Hydrogenolysis ..................... 569
13.8 Hydrogenolysis of Alkanes on Bimetallic Catalysts ........ 574
13.8.1 Introduction ...................................... 574
13.8.2 Metals of Groups 8 to 10 plus Group 11 ............ 575
13.8.3 Metals of Groups 8 to 10 plus Groups 13 or 14 ..... 578
13.8.4 Platinum and Iridium plus Zirconium, Molybdenum,
and Rhenium ....................................... 579
13.8.5 Bimetallic Catalysts of Metals of Groups 8 to
10 ................................................ 583
13.9 Apologia ................................................. 583
References ............................................... 583
14.2.3 Reactions of Linear Alkanes with Hydrogen ......... 602
14.2.4 Reactions of Branched Alkanes with Hydrogen ....... 609
14.2.5 Reactions of Cyclic Alkanes with Hydrogen ......... 616
14.2.6 The Environment of the Active Site: Effect of
'Carbon' .......................................... 621
CHAPTER 14 REACTIONS OF HIGHER ALKANES WITH HYDROGEN
14.1 Introduction: Petroleum Reforming and Reactions of
Higher Alkanes with Hydrogen.............................. 592
14.1.1 The Scope of This Chapter ......................... 592
14.1.2 Bifunctional Catalysis: Principles of Petroleum
Reforming .......................... .............. 592
14.1.3 Reactions of the Higher Alkanes with Hydrogen ..... 596
14.1.4 The Scope and Limitations of the Literature ....... 597
14.1.5 The Principal Themes .............................. 598
14.2 Reactions of Higher Alkanes with Hydrogen: Rates and
Product Selectivities .................................... 599
14.2.1 Activities of Pure Metals ......................... 599
14.2.2 Effect of Varying Conversion ...................... 601
14.3 Mechanisms of Alkane Transformations ..................... 624
14.3.1 A General Overview ................................ 624
14.3.2 Mechanisms of Skeletal Isomerisation .............. 625
14.3.3 Dehydrocyclisation ................................ 628
14.4 Structure-Sensitivity .................................... 629
14.4.1 Reactions on Single-Crystal Surfaces .............. 629
14.4.2 Particle-Size Effects with Supported Metals ....... 630
14.5 Modification of the Active Centre ........................ 634
14.5.1 Introduction ...................................... 634
14.5.2 Metal Particles in Zeolites ....................... 634
14.5.3 Platinum-Rhenium Catalysts ........................ 635
14.5.4 Modification by Elements of Groups 14 and 15 and
Some Others ....................................... 637
14.5.5 Other Bimetallic Catalysts ........................ 639
14.5.6 The Role of Sulfur ................................ 643
14.5.7 Metal-Support Interactions ........................ 644
References ............................................... 647
INDEX ......................................................... 657
|
