Chapter 1
Industrial Catalysts
1.1 Introduction ............................................... 1
1.2 What is a Catalyst? ........................................ 5
1.2.1 Activity ............................................ 6
1.2.2 Selectivity and Yield ............................... 7
1.2.3 Stability ........................................... 7
1.2.4 Strength ............................................ 8
1.3 Catalyst Production ................................... 8
1.3.1 Precipitation ...................................... 12
1.3.2 Impregnation ....................................... 13
1.3.3 Other Production Methods ........................... 13
1.4 Catalyst Testing .......................................... 14
1.4.1 Physical Tests ..................................... 14
1.4.2 Chemical Composition ............................... 14
1.4.3 Activity Testing ................................... 15
1.5 Catalyst Operation ........................................ 18
1.5.1 Reactor Design ..................................... 18
1.5.2 Catalytic Reactors ................................. 18
1.5.3 Catalyst Operating Conditions ...................... 20
1.6 Conclusion ................................................ 21
References ................................................ 22
Chapter 2
The First Catalysts
2.1 Sulfuric Acid ............................................. 23
2.1.1 The Lead Chamber Process .......................... 24
2.1.1.1 Chemistry of the Lead Chamber Process ... 26
2.1.1.2 The Continuing Use of the Lead Chamber
Process .................................. 27
2.1.1.3 Raw Material for Sulfuric Acid
Production ............................... 28
2.1.2 Contact Process Development ........................ 29
2.1.3 Modern Sulfuric Acid Processes ..................... 35
2.1.3.1 Catalyst Preparation ..................... 36
2.1.3.2 Sulfuric Acid Plant Design ............... 37
2.1.3.3 Cesium-Promoted Catalysts ................ 38
2.1.3.4 Sulfuric Acid Plant Operation ............ 39
2.1.3.5 Improved Catalyst Shapes ................. 39
2.2 The Deacon Process ........................................ 39
2.2.1 The Process ........................................ 40
2.2.2 Operation .......................................... 40
2.2.3 Catalyst Preparation ............................... 41
2.2.4 Development ........................................ 41
2.3 Claus Sulfur Recovery Process ............................. 41
2.3.1 The Claus Process .................................. 42
2.3.2 Claus Plant Operation .............................. 42
2.3.3 Claus Process Catalysts ............................ 45
2.3.4 Catalyst Operation ................................. 46
2.4 Ammonia Synthesis ......................................... 48
2.4.1 Sir William Crookes ................................ 49
2.4.2 Development of the Ammonia Synthesis Process ....... 51
2.4.3 Commercial Application of Ammonia Synthesis
Catalysts .......................................... 52
2.4.4 The Haber-Bosch Synthesis Reactor .................. 53
2.4.5 Conclusions ........................................ 54
2.5 Coal Hydrogenation ........................................ 55
2.5.1 The Bergius Process ................................ 55
2.5.2 Commercial Development by I.G. Farben .............. 56
2.5.3 Cooperation between I. G. Farben and Standard
Oil ................................................ 56
2.5.4 Commercial Developments by ICI ..................... 56
2.5.5 International Cooperation .......................... 57
2.5.6 Coal Hydrogenation Processes ....................... 57
2.5.6.1 The I. G. Farben Process ................. 58
2.5.6.2 The ICI Process .......................... 59
2.5.7 Catalysts for Coal Hydrogenation ................... 60
2.5.8 Creosote and Other Feeds ........................... 61
2.6 The Fischer-Tropsch Process ............................... 63
2.6.1 Postwar Development of the Synthol Process by
Sasol .............................................. 65
2.6.2 The Importance of Gas-to-Liquids as Gasoline
Prices Increase .................................... 68
References ................................................ 69
Chapter 3
Hydrogenation Catalysts
3.1 The Development of Hydrogenation Catalysts ................. 73
3.1.1 Sabatier and Senderens ............................. 73
3.1.2 The First Industrial Application of Nickel
Catalysts .......................................... 75
3.1.3 Ipatieff and High-Pressure Hydrogenation of
Liquids ............................................ 75
3.1.4 Colloidal Platinum and Palladium Catalysts by
Paal ............................................... 76
3.1.5 Platinum and Palladium Black Catalysts by
Willstatter ........................................ 76
3.1.6 Adams' Platinum Oxide .............................. 78
3.1.7 Raney Nickel Catalysts ............................. 78
3.1.8 Nickel Oxide/Kieselguhr Catalysts .................. 80
3.1.9 Nickel Oxide-Alumina Catalysts ..................... 83
3.1.10 Copper Chromite Catalysts .......................... 85
3.1.11 Copper Oxide/Zinc Oxide Catalysts .................. 86
3.2 Hydrogenation of Fats and Oils ............................ 89
3.2.1 Process Development ................................ 89
3.2.2 Oil Hydrogenation .................................. 90
3.2.3 Fat Hardening Catalysts ............................ 91
3.2.4 Catalyst Selectivity ............................... 93
3.2.5 Feed Pretreatment .................................. 94
3.2.6 Catalyst Operation ................................. 94
3.2.7 Catalyst Poisons ................................... 96
3.3 Fatty Acid Hydrogenation .................................. 96
3.4 The Production of Fatty Alcohols .......................... 97
3.4.1 Natural Fatty Alcohols ............................. 97
3.4.2 Catalyst Operation ................................. 98
3.4.3 Reaction of Fatty Alcohols ......................... 98
3.5 Some Industrial Hydrogenation Processes ................... 99
3.5.1 Nitrobenzene Reduction ............................. 99
3.5.2 Benzene Hydrogenation ............................. 100
3.5.2.1 Removal of Aromatics ..................... 101
3.5.3 Hydrogenation of Phenol ........................... 101
3.6 Selective Hydrogenation of Acetylenes and Dienes ......... 102
3.6.1 Acetylene Hydrogenation Process Design ............ 104
3.6.2 Early Acetylene Hydrogenation Catalysts ........... 105
3.6.2.1 Sulfided Cobalt Molybdate ................ 105
3.6.2.2 Sulfided Nickel Oxide .................... 105
3.6.2.3 Fused Iron Oxide ......................... 106
3.6.2.4 Palladium Catalyst Guard Beds ............ 106
3.6.3 Modern Acetylene Hydrogenation Catalysts .......... 106
3.6.4 Acetylene Hydrogenation Catalyst Preparation ...... 107
3.6.5 Acetylene Hydrogenation Catalyst Operation ........ 107
3.6.5.1 Tail-End Acetylene Hydrogenation ......... 107
3.6.5.2 Tail-End Methyl Acetylene/Propadiene
Hydrogenation ............................ 109
3.6.5.3 Front-End Acetylene Hydrogenation ........ 110
3.6.6 Selective Hydrogenation of Pyrolysis Gasoline ..... 112
3.6.6.1 Catalyst Types ........................... 113
3.6.6.2 Catalyst Operation ....................... 114
References ............................................... 115
Chapter 4
Oxidation Catalysts
4.1 Nitric Acid .............................................. 120
4.1.1 The Ammonia Oxidation Process ..................... 124
4.1.2 Catalyst Operation ................................ 128
4.1.3 Platinum Recovery ................................. 130
4.2 Formaldehyde ............................................. 131
4.2.1 Silver Catalyst Operation ......................... 136
4.2.2 Mixed Oxide Catalyst Operation .................... 136
4.3 Andrussov Synthesis of Hydrogen Cyanide .................. 137
4.4 Hopcalite Catalysts For Carbon Monoxide Oxidation ........ 139
4.5 Phthalic Anhydride ....................................... 140
4.5.1 Naphthalene Oxidation ............................. 141
4.5.2 Orthoxylene Oxidation ............................. 142
4.6 Maleic Anhydride ......................................... 144
4.6.1 Benzene Feedstock ................................. 144
4.6.2 n-Butene Feedstock ................................ 144
4.6.3 n-Butane Feedstock ................................ 148
4.6.4 n-Butane Oxidation in a Circulating Fluidized
Bed ............................................... 149
4.7 Ethylene Oxide ........................................... 150
4.7.1 Catalyst .......................................... 152
4.7.2 Operation and Reaction Mechanism .................. 153
4.7.3 Applications of Ethylene Oxide .................... 154
4.8 A Redox Oxidation Mechanism: Mars and Van Krevelen ....... 155
4.9 Acrolein and Acrylonitrile ............................... 156
4.9.1 Manufacture of Mixed Oxide Catalysts for
Acrolein and Acrylonitrile ........................ 157
4.9.2 The Acrylonitrile Process ......................... 158
4.9.3 Reaction Mechanism ................................ 159
4.9.4 Partial Oxidation of Propane ...................... 161
4.9.5 Acrylic Acid ...................................... 161
4.9.6 Oxidation of Isobutene ............................ 162
4.10 Oxidative Dehydrogenation of n-Butenes to Butadiene ...... 162
References ............................................... 163
Chapter 5
Catalytic Cracking Catalysts
5.1 Introduction ............................................. 169
5.2 Process Development ...................................... 170
5.2.1 Fixed Beds ........................................ 170
5.2.2 Moving and Fluidized Beds ......................... 171
5.2.3 Catalyst Regeneration and Carbon Monoxide
Combustion ........................................ 175
5.2.3.1 Catalyst Regeneration .................... 175
5.2.3.2 Carbon Monoxide Combustion Promoter ...... 176
5.2.4 Equilibrium Catalyst .............................. 177
5.2.5 Reaction Mechanism of Catalytic Cracking
Reactions ......................................... 178
5.3 Catalyst Development ..................................... 180
5.3.1 Natural Clay Catalysts ............................ 181
5.3.2 Synthetic Silica Alumina Catalysts ................ 182
5.3.3 Preparation of Synthetic Catalysts ................ 182
5.4 Zeolite Catalysts ........................................ 184
5.4.1 Commercial Zeolites ............................... 185
5.4.2 Production of Zeolites ............................ 188
5.4.3 Formation of Active Sites by Ion Exchange ......... 189
5.4.4 Use of Zeolites in Catalytic Cracking ............. 190
5.4.5 The Catalyst Matrix ............................... 191
5.5 Octane Catalysts (Catalysts to Increase Octane Rating) ... 192
5.5.1 Hydrothermal Dealumination ofY-Zeolites ........... 193
5.5.2 Chemical Dealumination of Y-Zeolites .............. 195
5.5.3 Increasing Octane Number .......................... 196
5.5.4 Shape Selective Cracking .......................... 197
5.6 Residue Cracking Catalysts ............................... 198
5.6.1 Residual Feeds .................................... 198
5.6.2 Residue Catalyst Formulation ...................... 199
5.6.3 Coke Formation .................................... 199
5.7 Residue Catalyst Additives ............................... 201
5.7.1 Nickel Additives .................................. 201
5.7.2 Vanadium Additives ................................ 202
5.7.3 Sulfur Oxides Transfer Additives .................. 203
5.7.4 Bottoms Cracking Additive ......................... 206
5.8 Reformulated Gasoline .................................... 206
References ............................................... 209
Chapter 6
Refinery Catalysts
6.1 The Development of Catalytic Refinery Processes .......... 211
6.2 Polymer Gasoline ......................................... 213
6.3 Alkylation ............................................... 217
6.3.1 Liquid Acid Processes ............................. 219
6.3.2 The Mechanism of Alkylation with an Acid
Catalyst .......................................... 219
6.3.3 Liquid Acid Operating Conditions .................. 220
6.3.4 Processes Using Solid-State Acid Catalysts ........ 221
6.4 Hydrotreating ............................................ 221
6.4.1 What Is Hydrotreating? ............................ 223
6.4.2 Hydrotreating Processes ........................... 223
6.4.2.1 Catalyst Production and Operation ........ 224
6.4.2.2 Catalyst Handling ........................ 225
6.4.2.3 Activating the Catalyst .................. 227
6.4.2.4 Catalyst Operation ....................... 229
6.4.2.5 Catalyst Regeneration .................... 229
6.5 Hydrocracking ............................................ 231
6.5.1 Hydrocracking Processes ........................... 232
6.5.1.1 Single-Stage Processes ................... 233
6.5.1.2 Two-Stage Processes ...................... 234
6.5.1.3 Once-Through Process ..................... 234
6.5.2 Hydrocracking Catalysts ........................... 235
6.5.2.1 Acid Supports ............................ 235
6.5.2.2 Hydrogenation Catalysts .................. 236
6.5.2.3 Catalyst Preparation ..................... 236
6.5.2.4 Catalyst Activity ........................ 237
6.5.2.5 Catalyst Reactivation .................... 237
6.6 Catalytic Reforming ...................................... 238
6.6.1 Naphtha Reforming Reactions ....................... 240
6.6.1.1 Reformer Operation ....................... 240
6.6.1.2 Coke Formation ........................... 246
6.6.2 Reforming Catalysts ............................... 247
6.6.2.1 Bimetallic Catalysts ..................... 248
6.6.2.2 Catalyst Preparation ..................... 250
6.6.3 Catalyst Regeneration ............................. 251
6.6.3.1 Carbon Burn .............................. 252
6.6.3.2 Oxychlorination .......................... 252
6.6.3.3 Platinum Re-Dispersal .................... 252
6.6.3.4 Catalyst Reduction ....................... 253
6.6.4 Catalyst Life ..................................... 253
6.7 Octane Boosting .......................................... 253
6.7.1 Selectoforming .................................... 253
6.7.2 M-Forming ......................................... 254
6.8 Aromatics Production ..................................... 254
6.8.1 Aromatics Process ................................. 254
6.8.2 Cyclar Process .................................... 255
6.8.3 M2-Forming Process ................................ 255
6.9 Catalytic Dewaxing ....................................... 255
6.10 Isomerization ............................................ 256
6.10.1 Isomerization Catalysts .......................... 256
6.10.2 Reaction Mechanism ............................... 257
References ............................................... 258
Chapter 7
Petrochemical Catalysts
7.1 The Development of Petrochemicals ........................ 261
7.1.1 Isopropyl Alcohol ................................. 265
7.1.1.1 Acetone .................................. 265
7.1.1.2 Bisphenol-A .............................. 266
7.1.1.3 Cumene ................................... 266
7.1.2 Vinyl Chloride .................................... 267
7.1.2.1 The Oxychlorination Reaction ............. 270
7.1.2.2 Oxychlorination Catalyst ................. 270
7.1.2.3 Catalyst Operation ....................... 271
7.2 Synthetic Rubber From Butadiene and Styrene .............. 273
7.2.1 Butadiene from Butane ............................. 275
7.2.2 Butadiene from Butenes ............................ 275
7.2.2.1 Oxidative Dehydrogenation ................. 277
7.2.3 Propylene from Propane ............................ 277
7.2.4 Styrene ........................................... 278
7.2.4.1 Ethylbenzene Production .................. 279
7.2.4.2 Styrene Production after 1950 ............ 281
7.2.4.3 Styrene Plant Operation .................. 282
7.2.4.4 Ethylbenzene Dehydrogenation (Styrene)
Catalysts ................................ 283
7.3 Synthetic Fibers ......................................... 283
7.3.1 Nylon 66 .......................................... 284
7.3.1.1 Production of Nylon Intermediates ........ 285
7.3.1.2 Adipic Acid .............................. 285
7.3.1.3 Hexamethylenediamine ..................... 286
7.3.1.4 Nylon Polymer ............................ 288
7.3.2 Nylon 6 ........................................... 289
7.3.2.1 Caprolactam .............................. 289
7.3.2.2 Cyclohexanone ............................ 290
7.3.2.3 Cyclohexanone Oxime ...................... 290
7.3.2.4 Snia-Viscosa Process ..................... 291
7.3.2.5 Conversion of Cyclohexanone Oxime to
Caprolactam .............................. 291
7.3.2.6 Caprolactam from Butadiene ............... 292
7.3.3 Polyesters ........................................ 292
7.3.3.1 Paraxylene ............................... 293
7.3.3.2 Terephthalic Acid ........................ 294
7.3.3.3 Alternative Routes for Terephthalic
Acid Production .......................... 296
7.3.3.4 Use of Polyesters ........................ 296
7.4 Hydroformylation and Carbonylation ....................... 297
7.4.1 Cobalt Carbonyl Catalysts ......................... 297
7.4.2 Phosphine Modified Catalysts ...................... 298
7.4.3 Low-Pressure Hydroformylation ..................... 300
7.4.4 Commercial Operation .............................. 301
7.4.5 Acetic Acid ....................................... 301
7.4.6 Acetaldehyde ...................................... 303
7.5 Metathesis of Olefins .................................... 304
7.5.1 Process Development ............................... 304
7.5.2 The Shell Higher-Olefms Process ................... 305
References ............................................... 306
Chapter 8
Olefin Polymerization Catalysts
8.1 Low-Pressure Polyethylene ................................ 312
8.1.1 Polyethylene Process Development .................. 313
8.1.2 The Development of Polypropylene Catalysts ........ 314
8.2 Ziegler-Natta Catalysts .................................. 314
8.2.1 Early Polyolefin Catalysts ........................ 314
8.2.2 Ziegler's Brown Titanium Trichloride .............. 315
8.2.3 Natta's Violet Titanium Trichloride ............... 316
8.2.4 Second-Generation Propylene Polymerization
Catalysts ......................................... 317
8.2.5 Supported Polyethylene Catalysts .................. 319
8.2.6 Supported Polypropylene Catalysts ................. 320
8.2.6.1 Third-Generation Catalysts ............... 320
8.2.6.2 Fourth-Generation Catalysts .............. 321
8.3 Phillips Polyethylene Catalysts .......................... 322
8.3.1 Catalyst Production ............................... 323
8.3.2 Catalyst Reduction ................................ 324
8.3.4 Catalyst Operation ................................ 324
8.3.5 Catalyst Modifiers ................................ 325
8.3.5.1 Titanium ................................. 326
8.3.5.2 Alumina and Zirconia ..................... 327
8.3.5.3 Fluorides ................................ 327
8.3.6 Use of Co-catalysts ............................... 327
8.3.7 Organo-chromium Catalysts ......................... 328
8.4 Other Catalysts .......................................... 329
8.5 Polymerization Processes ................................. 329
8.5.1 Slurry Processes .................................. 332
8.5.2 Solution Processes ................................ 332
8.5.3 Gas Phase Process ................................. 333
8.6 Metallocene/Single-Site Catalysts ........................ 334
8.6.1 Early Development ................................. 335
8.6.2 Early Development ................................. 336
8.6.3 Industrial Operation .............................. 338
8.6.4 Catalyst Activators ............................... 338
8.6.5 Molecular Weight Control .......................... 339
8.6.7 New Catalyst Developments ......................... 340
8.7 The Molecular Structure of Polyolefins ................... 341
8.7.1 Formation of Polymer Chains ....................... 341
8.7.2 Polymer Chain Termination ......................... 342
8.7.3 Molecular Weight .................................. 344
References ............................................... 345
Chapter 9
Synthesis Gas
9.1 Ammonia Synthesis Gas .................................... 352
9.1.1 Process Developments .............................. 353
9.1.2 Increased Ammonia Production by Steam Reforming ... 354
9.2 Modern Ammonia Plants .................................... 355
9.3 Feedstock Purification ................................... 357
9.3.1 Activated Carbon .................................. 358
9.3.2 Hydrodesulfurization .............................. 358
9.3.3 Chlorine Removal .................................. 360
9.3.4 Sulfur Absorption ................................. 360
9.3.4.1 Operation with Zinc Oxide ................ 361
9.3.4.2 Preparation of Zinc Oxide ................ 363
9.3.4.3 Desulfurization of Other Gases ........... 363
9.4 Steam Reforming .......................................... 363
9.4.1 Reformer Design ................................... 365
9.4.2 Reforming Catalysts ............................... 369
9.4.3 Reformer Operation ................................ 371
9.4.4 Secondary Reforming ............................... 374
9.5 Carbon Monoxide Removal .................................. 375
9.5.1 High Temperature Carbon Monoxide Conversion ....... 376
9.5.2 High Temperature Conversion Catalysts ............. 377
9.5.2.1 Operating Conditions ........................... 378
9.5.3 Low Temperature Carbon Monoxide Conversion ........ 379
9.5.3.1 Operation ................................ 381
9.5.3.2 Catalyst ................................. 384
9.6 Methanation .............................................. 385
9.6.1 Operation ......................................... 386
9.6.2 Catalyst .......................................... 387
9.6.3 Other Methanation Processes ....................... 388
9.7 Other Applications of Steam Reforming .................... 389
9.7.1 Methanol Synthesis Gas ............................ 389
9.7.2 OXO Synthesis Gas ................................. 390
9.7.3 Hydrogen Production ............................... 390
9.7.4 Reducing Gas ...................................... 391
9.7.5 Town Gas Production ............................... 391
9.7.6 Substitute Natural Gas ............................ 392
9.7.7 Autothermal Reforming ............................. 393
References ............................................... 395
Chapter 10
Ammonia and Methanol Synthesis
10.1 Ammonia Synthesis ........................................ 397
10.1.1 Process Development from 1920 .................... 399
10.1.1.1 Haber-Bosch Process ...................... 399
10.1.1.2 Claude Process ........................... 400
10.1.1.3 Casale Process ........................... 401
10.1.1.4 United States of America ................. 402
10.1.1.5 Mont Cenis/Uhde Process .................. 403
10.1.1.6 United Kingdom ........................... 403
10.1.2 Ammonia Synthesis Catalysts ...................... 405
10.1.2.1 Catalyst Production ...................... 405
10.1.2.2 Pre-reduced Catalysts .................... 407
10.1.2.3 Loading Catalyst to Converter ............ 408
10.1.2.4 Catalyst Discharge from the Converter .... 409
10.1.3 Catalyst Reduction ................................ 409
10.1.3.1 Reduction of Oxidized Catalyst ........... 409
10.1.3.2 Reduction of Pre-reduced Catalyst ........ 410
10.1.3.3 Mechanism of Catalyst Reduction .......... 410
10.1.4 The Ammonia Synthesis Process ..................... 412
10.1.4.1 The Ammonia Synthesis Loop ............... 412
10.1.4.2 Converter Design ......................... 414
10.1.5 New Catalyst Developments ......................... 417
10.1.5.1 Magnetite Catalyst Containing Cobalt ..... 418
10.1.5.2 Ruthenium Catalyst ....................... 419
10.1.5.3 Catalyst Preparation ..................... 419
10.1.5.4 Full-scale Operation with Ruthenium
Catalyst ................................. 420
10.2 Methanol Synthesis ....................................... 421
10.2.1 High-pressure Synthesis ........................... 421
10.2.1.1 Zinc Oxide-Chromium Oxide Catalysts ...... 421
10.2.1.2 High-Pressure Operation .................. 423
10.2.2 Low-pressure Synthesis ........................... 425
10.2.2.1 Copper Oxide Catalysts ................... 426
10.2.2.2 Copper Catalyst Production ............... 426
10.2.2.3 Precipitates Forming During Production ... 430
10.2.2.4 Operation with Copper Catalysts .......... 431
10.2.2.5 Reaction Mechanism with Copper
Catalysts ................................ 432
10.2.2.6 Selectivity .............................. 432
10.2.2.7 Low-pressure Methanol Reactor Types ...... 433
10.2.2.8 Catalyst Reduction ....................... 433
10.3 Novel Catalysts ..................................... 434
References ............................................... 435
Chapter 11
Environmental Catalysts
11.1 Stationary Sources ....................................... 441
11.1.1 Selective Catalytic Reduction ..................... 443
11.1.2 Selective Catalytic Reduction Catalysts ........... 445
11.1.2.1 Catalyst Composition ..................... 446
11.1.2.2 Catalyst Operation ....................... 447
11.1.2.3 Reaction Mechanism ....................... 447
11.1.2.4 Removal of Sulfur Dioxide as Sulfuric
Acid ..................................... 448
11.1.3 Gas Turbine Exhausts ............................. 449
11.1.3.1 Low Temperature Vanadium Pentoxide
Catalysts ................................ 449
11.1.3.2 Catalytic Combustion Processes ........... 449
11.1.4 Nitric Acid Plant Exhaust Gas ..................... 450
11.1.5 Ion-exchanged ZSM-5 Zeolites ...................... 451
11.2 Mobile Sources ........................................... 452
11.2.1 Automobile Emission Control ....................... 452
11.2.2 Automobile Emission Control Catalysts ............. 455
11.2.2.1 Bead Catalysts ........................... 456
11.2.2.2 Monolith Catalysts ....................... 456
11.2.2.3 Washcoat Composition ..................... 457
11.2.2.4 Platinum Group Metal Catalysts ........... 458
11.2.2.5 Catalyst Poisons ......................... 459
11.2.3 Platinum Metal Group Availability ................. 460
11.2.4 Catalyst Operation ................................ 460
11.2.5 Nitrogen Oxide Removal in Lean-Burn Engines ....... 463
11.2.6 Diesel Engines .................................... 464
11.3 Volatile Organic Compounds ............................... 465
11.3.1 VOC Removal Processes ............................. 466
11.3.2 VOC Oxidation Catalysts ........................... 468
Reference ................................................ 469
Index ......................................................... 471
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