Selective oxidation by heterogeneous catalysis

Selective Oxidation by Heterogeneous Catalysis covers one of the major areas of industrial petrochemical production, outlining open questions and new opportunities. It gives keys for the interpretation and analysis of data and design of new catalysts and reactions, and provides guidelines for future research. A distinctive feature of this book is the use of concept by example. Rather than reporting an overview of the literature results, the authors have selected some representative examples, the in-depth analysis of which makes it possible to clarify the fundamental, but new concepts necessary for a better understanding of the new opportunities in this field and the design of new catalysts or catalytic reactions. Attention is given not only to the catalyst itself, but also to the use of the catalyst inside the process, thus evidencing the relationship between catalyst design and engineering aspects of the process. This book provides suggestions for new innovative directions of research and indications on how to reconsider the field of selective oxidation from different perspectives, outlining that is not a mature field of research, but that new important breakthroughs can be derived from fundamental and applied research. Suggestions are offered on how to use less conventional approaches in terms of both catalyst design and analysis of the data.

Author Notes

Gabriele Centi is Professor of Industrial Chemistry at the University of Messina, Italy.

Chapter 1. Trends and Outlook in Selective Oxidation: an Introduction
1.1. Introduction	p. 1
1.2. Technological and Industrial Developments	p. 5
1.2.1. New Raw Materials	p. 5
1.2.2. Conversion of Air-Based to Oxygen-Based Processes	p. 8
1.2.3. Fine-Tuning Existing Oxidation Processes	p. 10
1.2.4. Reducing the Number of Process Steps	p. 12
1.3. New Opportunities Derived from Basic Research	p. 13
1.4. The Ecological Issue as a Driving Force	p. 15
1.4.1. Reduction or Elimination of Coproducts	p. 15
1.4.1.1. Synthesis of Propene Oxide	p. 16
1.4.1.2. Synthesis of Cyclohexanone Oxime	p. 16
1.4.1.3. Synthesis of Methyl Methacrylate	p. 17
1.4.2. Use of Alternative Catalysts	p. 17
1.5. Heterogeneous Versus Homogeneous Catalysis in Selective Oxidation	p. 19
References	p. 22
Chapter 2. New Technological and Industrial Opportunities: Options
2.1. Use of Alternative Raw Materials	p. 25
2.1.1. Alkanes as Raw Materials for Selective Oxidation Reactions	p. 25
2.1.1.1. Advantages and Targets in Using an Alkane Feedstock	p. 26
2.1.1.2. Key Questions in Alkane Functionalization	p. 29
2.1.1.3. Processes of Industrial Interest Using an Alkane Feedstock	p. 30
2.1.2. New Oxidants	p. 32
2.1.2.1. Nitrous Oxide	p. 33
2.1.2.2. Ozone	p. 35
2.1.2.3. In Situ Generated Oxidants in the Liquid Phase	p. 35
2.2. New Reactor Technology Options	p. 37
2.2.1. Fixed-Bed Reactors	p. 38
2.2.1.1. The Problem of Hot Spots in Both the Axial and Radial Directions	p. 38
2.2.1.2. Heat and Mass Gradients	p. 39
2.2.1.3. Presence of Multiple Steady States and Runaway Phenomena	p. 43
2.2.1.4. Wide-Residence Time Distribution	p. 45
2.2.1.5. High Pressure Drop	p. 45
2.2.2. Technologies Designed to Overcome Drawbacks of Fixed-Bed Reactors	p. 46
2.2.2.1. Dual-Bed Reactors	p. 46
2.2.2.2. Distributed Inlet of One Reactant	p. 46
2.2.2.3. Periodic Flow Reversal	p. 47
2.2.2.4. Decoupling of the Exothermal Reaction into Two Steps	p. 48
2.2.2.5. Integration of Exothermal and Endothermal Processes	p. 49
2.2.2.6. Radial Flow Reactors	p. 49
2.2.3. Fluidized-Bed Reactors	p. 49
2.2.4. High-Gas-Velocity Systems: Circulating Fluidized-Bed Reactors	p. 53
2.2.5. Structured Catalysts and Reactors	p. 56
2.2.5.1. Monolith Reactors	p. 60
2.2.5.2. Membrane Reactors	p. 63
2.2.6. Electrochemical Cells as Reactors	p. 65
2.3. Air Versus Oxygen Processes	p. 67
2.3.1. Advantages in the Use of Oxygen Instead of Air in Industrial Oxidation Processes	p. 67
2.3.1.1. Synthesis of Ethene Epoxide	p. 69
2.3.1.2. Synthesis of 1,2-Dichloroethane (DCE)	p. 71
2.3.2. Use of Pure Oxygen in the Oxidation of Alkanes	p. 73
References	p. 74
Chapter 3. New Technological and Industrial Opportunities: Examples
3.1. Introduction	p. 85
3.2. Examples of Opportunities for New Oxidation Processes	p. 87
3.2.1. Selective Oxidation for Fine Chemicals and Pharmaceuticals	p. 87
3.2.1.1. Oxidation with Hydrogen Peroxide and Organic Peroxide	p. 87
3.2.1.2. Oxidation with Molecular Oxygen and Noble Metal-Based Catalysts	p. 91
3.2.1.3. Bioinorganic-Type Oxidation	p. 95
3.2.2. New Catalytic Processes for Bulk Chemicals Using Hydrogen Peroxide	p. 100
3.2.2.1. Alkene Epoxidation Reactions	p. 101
3.2.2.2. Cyclohexanone Ammoximation	p. 109
3.2.2.3. Hydroxylation of Phenols	p. 115
3.3. Examples of New Catalytic Systems	p. 120
3.3.1. Metalloporphyrin Complexes	p. 122
3.3.2. Polyoxometallates	p. 124
3.3.3. Supported Metals	p. 125
3.3.4. Isomorphically Substituted Molecular Sieves	p. 126
3.3.5. Redox Pillared Clays	p. 127
3.3.6. Phase-Transfer Catalysts	p. 128
3.3.7. Guest Oxide Nanoparticles within Host Zeo-Type Materials	p. 129
3.4. Conclusions	p. 132
References	p. 132
Chapter 4. Control of the Surface Reactivity of Solid Catalysts: Industrial Processes of Alkane Oxidation
4.1. Introduction	p. 141
4.2. Maleic Anhydride from n-Butane on Vanadium/Phosphorus Oxides	p. 143
4.2.1. Industrial Processes of Maleic Anhydride Synthesis from n-Butane	p. 143
4.2.1.1. Gas Phase Composition	p. 145
4.2.1.2. Reactor Technologies	p. 146
4.2.1.3. Catalyst Formulation	p. 148
4.2.2. V/P Oxide Catalysts Synthesis and Characteristics	p. 151
4.2.2.1. Role of the Precursor Phase	p. 151
4.2.2.2. Activation and Conditioning Procedure	p. 153
4.2.2.3. Role of the P/V Ratio and Catalyst Redox Properties	p. 156
4.2.2.4. Role of Promoters	p. 157
4.2.2.5. Structure of the V/P Oxide Phases	p. 158
4.2.3. Advanced Aspects toward Understanding the Catalytic Chemistry of V/P Oxides	p. 161
4.2.3.1. Role of Catalyst Microstructure and Topology	p. 161
4.2.3.2. In Situ Surface Restructuring of VPO Catalysts	p. 166
4.2.3.3. Catalyst Properties and Reactor/Process Configuration	p. 168
4.2.3.4. Microkinetics of the Surface Transformations on V/P Oxide Catalysts	p. 170
4.2.3.5. Alkane versus Alkene Oxidation	p. 170
4.3. Propane Ammoxidation to Acrylonitrile on Vanadium/Antimony Oxides	p. 171
4.3.1. Background on the Direct Synthesis of Acrylonitrile from Propane	p. 171
4.3.2. Role of Nonstoichiometry and Rutile Structure in V/Sb Oxide Catalysts	p. 173
4.3.2.1. Comparison with Other Sb-Rich Rutilelike Mixed Oxide Catalysts	p. 175
4.3.2.2. Nature of the Phases Present	p. 176
4.3.2.3. Nonstoichiometry of Vanadium Antimonate and Catalytic Reactivity	p. 177
4.3.2.4. Nonstoichiometry of Vanadium Antimonate and Surface Characteristics	p. 182
4.3.2.5. Role of Microstructure	p. 184
4.3.3. Surface Reaction Network as a Tool for Understanding and Controlling Reactivity	p. 185
4.3.3.1. The Surface Reaction Network in Propane Ammoxidation over V/Sb Oxide Catalysts	p. 186
4.3.3.2. The Surface Reaction Network as a Tool for Understanding the Surface Reactivity	p. 187
4.3.3.3. Designing Better Catalysts	p. 190
4.3.3.4. Conclusions	p. 191
References	p. 192
Chapter 5. Control of the Surface Reactivity of Solid Catalysts: New Alkane Oxidation Reactions
5.1. Introduction	p. 203
5.2. Oxidative Dehydrogenation of Alkanes	p. 204
5.2.1. Dehydrogenation versus Oxidative Dehydrogenation	p. 204
5.2.2. Constraints in Oxidative Dehydrogenation	p. 207
5.2.3. Class of Catalysts Active in Oxidative Dehydrogenation	p. 214
5.2.3.1. Alkali and Alkaline Earth-Based Catalysts	p. 215
5.2.3.2. Catalysts Based on Transition Metal Oxides	p. 220
5.2.3.3. Catalysts and Reaction Mechanisms	p. 226
5.2.4. Role of the Nature of the Alkane	p. 230
5.2.5. Conclusions	p. 239
5.3. New Types of Oxidation of Light Alkanes	p. 241
5.3.1. Introduction	p. 241
5.3.2. Ethane Conversion	p. 243
5.3.2.1. Catalysts for Acetaldehyde and Acetic Acid Formation	p. 243
5.3.2.2. Alternative Approaches for Catalyst Design	p. 246
5.3.2.3. A New Route: Ethane Ammoxidation	p. 249
5.3.3. Propane Conversion	p. 253
5.3.3.1. Acrolein Synthesis	p. 253
5.3.3.2. Acrylic Acid Synthesis	p. 256
5.3.4. Isobutane Conversion to Methacrolein and Methacrylic Acid	p. 259
5.3.5. n-Pentane Conversion to Maleic and Phthalic Anhydrides	p. 266
5.3.6. Cyclohexane (Amm)oxidation	p. 271
References	p. 272
Chapter 6. New Fields of Application for Solid Catalysts
6.1. Introduction	p. 285
6.2. Selective Oxidation in the Liquid Phase with Solid Micro- or Mesoporous Materials	p. 287
6.2.1. Framework Substitution	p. 289
6.2.2. Synthesis, Characteristics, and Reactivity of Titanium Silicalite	p. 290
6.2.2.1. Reactivity	p. 290
6.2.2.2. Synthesis	p. 291
6.2.2.3. Characterization	p. 293
6.2.2.4. Nature of Active Species	p. 294
6.2.3. Encapsulated Metal Complexes	p. 298
6.2.4. Grafting or Tethering of Metal Complexes	p. 298
6.2.5. New "Hydrophobic" Catalytic Materials for Liquid Phase Epoxidation of Alkenes	p. 299
6.3. Heteropoly Compounds as Molecular-Type Catalysts	p. 300
6.3.1. Introduction	p. 300
6.3.2. Redox Properties of HPCs	p. 301
6.3.3. Liquid Phase Oxidation	p. 303
6.3.3.1. Oxidation with Molecular Oxygen	p. 303
6.3.3.2. Oxidation with Hydrogen Peroxide, with Organic Peroxides or Other Monoxygen Donors	p. 305
6.3.4. Gas Phase Oxidation: General Aspects	p. 309
6.4. Solid Wacker-Type Catalysts	p. 310
6.4.1. Palladium Supported on Monolayer-Type Redox Oxides	p. 311
6.4.2. Solid Palladium-Heteropoly Compounds	p. 313
6.4.3. Heterogenization of Wacker Catalysts in Microporous Materials	p. 314
References	p. 315
Chapter 7. New Concepts and New Strategies in Selective Oxidation
7.1. Introduction	p. 325
7.2. Selective Oxidation at Near Room Temperature Using Molecular Oxygen	p. 326
7.2.1. Electrochemical Activation of Molecular Oxygen	p. 327
7.2.1.1. Benzene to Phenol	p. 328
7.2.1.2. Alkane Oxidation	p. 330
7.2.1.3. [pi]-Allyl and Wacker Oxidation of Alkenes	p. 331
7.2.2. Activation of Molecular Oxygen by Spontaneous Charge Transfer from a Hydrocarbon	p. 334
7.2.2.1. Oxidation of Alkenes	p. 336
7.2.2.2. Oxidation of Alkylaromatics	p. 337
7.2.2.3. Oxidation of Alkanes	p. 337
7.2.3. Singlet Molecular Oxygen	p. 339
7.3. New Approaches to Generate Active Oxygen Species	p. 340
7.3.1. In Situ Generation of Monoxygen Donors	p. 340
7.3.1.1. Methods of in Situ Generation of H[subscript 2]O[subscript 2]	p. 341
7.3.1.2. Oxidation Reactions with in Situ Generated Hydrogen Peroxide	p. 344
7.3.2. Generation of Active Oxygen Species by Ozone	p. 345
7.3.3. Use of Nitrous Oxide as a Selective Oxidant	p. 345
7.3.3.1. Reactivity of [alpha]-Oxygen	p. 346
7.3.3.2. Use of Waste Nitrous Oxide Streams: Adipic Acid Production	p. 348
7.4. Novel Reaction Mediums	p. 350
7.4.1. Oxidation Reaction at Thin Supported Liquid Films	p. 350
7.4.1.1. Heterogeneous Wacker-Type Catalysts	p. 350
7.4.1.2. Ethene Acetoxylation to Vinyl Acetate	p. 352
7.4.1.3. Other Cases	p. 354
7.4.2. Oxidation Reaction under Supercritical Conditions	p. 355
7.5. Conclusions	p. 356
References	p. 357
Chapter 8. New Aspects of the Mechanisms of Selective Oxidation and Structure/Activity Relationships
8.1. Introduction	p. 363
8.1.1. Outline and Scope of this Chapter	p. 363
8.1.2. The Established Approach to Modeling Reaction Mechanisms at Oxide Surfaces	p. 364
8.2. Active Sites or "Living Active Surface"?	p. 369
8.2.1. The Mechanism of Propene (Amm)oxidation	p. 369
8.2.2. Analysis of the Model of the Mechanism of Propene (Amm)oxidation	p. 370
8.2.3. Toward a Model of "Living Active Surface" Rather than Localized Catalysis at Active Sites	p. 372
8.2.4. The Question of Stepwise Reaction Mechanisms	p. 375
8.2.5. The Geometrical Approach to Oxidation Catalysis at Oxide Surfaces	p. 376
8.2.6. The Question of Reaction at a Single "Ensemble" Site	p. 379
8.2.7. The Role of Catalyst Reduction and Dynamics of Reaction	p. 381
8.2.8. General Conclusions on the Modeling Approach to Selective Oxidation Catalysis	p. 384
8.3. Surface Oxygen Species and Their Role in Selective Oxidation	p. 386
8.3.1. Nature of the Interaction between Molecular Oxygen and Oxide Surfaces and Types of Oxygen Adspecies	p. 388
8.3.1.1. Neutral Dioxygen Species	p. 389
8.3.1.2. Charged Dioxygen Species	p. 390
8.3.1.3. Monoxygen Species	p. 392
8.3.2. Reactivity of Adsorbed Oxygen Species	p. 395
8.3.3. New Aspects of the Reactivity of Surface Oxygen Species	p. 398
8.4. Modification of the Surface Reactivity by Chemisorbed Species	p. 413
8.4.1. The Role of Alkenes in the Self-Modification of the Surface Reactivity	p. 414
8.4.2. The Role of the Nature of Intermediate Products	p. 418
8.4.3. Chemisorption and Change in the Surface Pathways of Transformation	p. 420
8.4.4. Direct Role of Chemisorbed (Spectator) Species in the Reaction Mechanism	p. 422
8.5. Role of Acido-Base Properties in Catalytic Oxidation	p. 425
8.5.1. Basic Concepts on the Acido-Base Characteristics of Metal Oxides	p. 426
8.5.2. Influence of Acido-Base Characteristics on the Activation of Hydrocarbons	p. 429
8.5.3. Competitive Surface Reactions and Acido-Base Properties	p. 431
8.5.4. Role of Acido-Base Properties on the Adsorption/Desorption of Reactants and Products	p. 438
8.6. Reactive Intermediates in Heterogeneous Oxidative Catalysis	p. 439
8.6.1. Analysis of the Reactive Intermediates by IR Spectroscopy	p. 439
8.6.2. Chemistry of Oxidation of Methanol	p. 441
8.6.3. Oxidation of Linear C4 Hydrocarbons	p. 446
8.6.4. Oxidation of Alkylaromatics	p. 449
8.6.5. The Case of Ammonia	p. 454
8.7. Presence of Competitive Pathways of Conversion and Factors Governing Their Relative Rates	p. 456
8.7.1. Propane Ammoxidation on (VO)[subscript 2]P[subscript 2]O[subscript 7]	p. 457
8.7.2. Toluene Ammoxidation on (VO)[subscript 2]P[subscript 2]O[subscript 7] and V/TiO[subscript 2] Catalysts	p. 459
8.7.3. Propane Ammoxidation on V/Sb Oxides	p. 461
8.7.4. o-Xylene Ammoxidation on V/TiO[subscript 2] Catalysts	p. 466
8.7.5. Oxidation of n-Pentane on (VO)[subscript 2]P[subscript 2]O[subscript 7]	p. 468
8.8. Dynamics of Catalytic Oxidation Processes	p. 469
8.8.1. Relevant Evidence from Surface Science Studies	p. 470
8.8.2. Dynamics of Oxide Phase Transformation in the Active Form of the Catalysts	p. 475
8.8.3. Dynamics of Surface Species and Their Effect on Catalyst Surface Properties	p. 477
8.9. Conclusions	p. 478
References	p. 480
Chapter 9. General Conclusions	p. 497
Index	p. 501

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