Microwaves in Catalysis

List of Contributors XVII Preface XXI 1 General Introduction to Microwave Chemistry 1 Satoshi Horikoshi and Nick Serpone 1.1 ElectromagneticWaves and Dielectric Materials 1 1.2 Microwave Heating 2 1.3 The Various Types of Microwave Heating Phenomena 4 1.3.1 Conduction Loss Heating (Eddy Current Loss and Joule Loss) 5 1.3.2 Dielectric Heating 5 1.3.3 Magnetic Loss Heating (Eddy Current Loss and Hysteresis Loss Heating) 6 1.3.4 Penetration Depth of Microwaves 6 1.4 Fields of Applications with Microwave Heating 9 1.5 Microwaves in Solid Material Processing 11 1.6 Microwaves in Organic Syntheses 12 1.7 Microwave Chemical Equipment 12 1.8 Chemical Reactions Using the Characteristics of Microwave Heating 17 1.9 Microwave Frequency Effect in Chemical Syntheses 21 1.10 Summary 25 References 25 Part I Fundamentals 29 2 Loss Mechanisms and Microwave-Specific Effects in Heterogeneous Catalysis 31 A.E. Stiegman 2.1 Introduction 31 2.2 Heterogeneous Catalyst Systems 33 2.3 Physics of Microwave Absorption 33 2.4 Microwave Loss Processes in Solids 35 2.4.1 Dielectric Loss 35 2.4.2 Charge Carrier Processes 36 2.4.2.1 Conduction Loss 36 2.4.2.2 Space–Charge Recombination 37 2.4.2.3 Dipolar Loss 38 2.4.3 Magnetic Loss Processes 40 2.5 Loss Processes and Microwave-Specific Catalysis: Lessons from Gas–Carbon Reactions 41 2.5.1 Thermochemical Considerations 42 2.6 Final Comments on Microwave-Specific Effects in Heterogeneous Catalysis 45 Acknowledgments 45 References 46 3 Transport Phenomena and Thermal Property under Microwave Irradiation 49 Yusuke Asakuma 3.1 Introduction 49 3.2 Bubble Formation 50 3.3 Convection 53 3.4 Surface Tension 56 3.5 Discussion of Nonthermal Effect for Nanobubble Formation 58 References 59 4 Managing Microwave-Induced Hot Spots in Heterogeneous Catalytic Systems 61 Satoshi Horikoshi and Nick Serpone 4.1 What Are Hot Spots? 61 4.2 Microwaves in Heterogeneous Catalysis 61 4.3 Microwave-Induced Formation of Hot Spots in Heterogeneous Catalysis 63 4.3.1 Hot Spot Phenomenon 63 4.3.2 Mechanism(s) of Formation of Hot Spots 68 4.3.3 Particle Aggregation by Polarization of Activated Carbon Particulates 69 4.3.4 Control of the Occurrence of Hot Spots 73 References 75 Part II Applications – Preparation of Heterogeneous Catalysts 77 5 Preparation of Heterogeneous Catalysts by a Microwave Selective Heating Method 79 Satoshi Horikoshi and Nick Serpone 5.1 Introduction 79 5.2 Synthesis of Metal Catalysts on Carbonaceous Material Supports 79 5.3 Photocatalysts 81 5.3.1 Preparation of TiO2/AC Particles 83 5.3.2 Proposed Mechanism of Formation of TiO2/AC Particles 86 5.3.3 Photoactivity ofMW-Prepared TiO2/AC Composite Particles in the Degradation of Isopropanol 87 5.4 Microwave-Assisted Syntheses of Catalytic Materials for Fuel Cell Applications 88 5.4.1 Microwave-Assisted Synthesis of Pt/C Catalyst Particulates for a H2 Fuel Cell 89 5.4.2 Preparation of Nanocatalysts for a Methanol Fuel Cell 91 5.4.3 Effects of pH on Pt Particle Size and Electrocatalytic Activity of Pt/CNTs for Methanol Electro-oxidation 93 5.5 Other Catalysts Prepared by Microwave-Related Procedures 94 5.6 Concluding Remarks 103 References 103 Part III Applications – Microwave Flow Systems and Microwave Methods Coupled to Other Techniques 109 6 Microwaves in Cu-Catalyzed Organic Synthesis in Batch and Flow Mode 111 Faysal Benaskar, Narendra Patil, Volker Rebrov, Jaap Schouten, and Volker Hessel 6.1 Introduction 111 6.2 Microwave-Assisted Copper Catalysis for Organic Syntheses in Batch Processes 112 6.2.1 Bulk and Nano-structured Metals in a Microwave Field 112 6.2.1.1 Interaction of Bulk Metal with Microwaves 112 6.2.1.2 Metallic Catalyst Particle Size and Shape Effect on Microwave Heating 113 6.2.1.3 Polymetallic Systems in Microwave Chemistry 115 6.2.2 Microwave-Assisted Copper Catalysis for Chemical Synthesis 116 6.2.2.1 Bulk Copper Particles for Catalysis and Microwave Interaction 116 6.2.2.2 Microwave-Assisted Copper-Catalyzed Bond Formation Reactions 117 6.2.3 Supported Cu-Based Catalyst for Sustainable Catalysis in Microwave Field 120 6.2.3.1 Microwave Activation and Synthesis of Cu-Based Heterogeneous Catalysts 120 6.2.3.2 Cu-Supported Catalyst Systems for C–O, C–C, C–S, and C–N Coupling Reactions 121 6.3 Microwave-Assisted Copper Catalysis for Organic Syntheses in Flow Processes 122 6.3.1 Microwave-Assisted Catalyzed Organic Synthesis in Flow Processes 122 6.3.1.1 Microwave Heating in Homogeneously Catalyzed Processes 122 6.3.1.2 Microwave Energy Efficiency and Uniformity in Catalyzed Flow Processes 124 6.3.2 Structured Catalyst in Microwave-Assisted Flow Processing for Organic Reactions 130 6.3.2.1 Thin-Film Flow Reactors for Organic Syntheses 130 6.3.2.2 Structured Fixed-Bed Reactors for Flow Synthesis 131 6.3.2.3 Scale-Up of Microwave-Assisted Flow Processes 133 6.4 Concluding Remarks 136 References 136 7 Pilot Plant for Continuous Flow Microwave-Assisted Chemical Reactions 141 Mitsuhiro Matsuzawa and Shigenori Togashi 7.1 Introduction 141 7.2 Continuous Flow Microwave-Assisted Chemical Reactor 142 7.2.1 Basic Structure 142 7.3 Pilot Plant 145 7.3.1 Design ofWaveguide 145 7.3.2 Configuration of Pilot Plant 147 7.3.3 Water Heating Test 148 7.3.4 Sonogashira Coupling Reaction 151 7.4 Conclusions 153 Acknowledgment 154 References 154 8 Efficient Catalysis by Combining Microwaves with Other Enabling Technologies 155 Giancarlo Cravotto, Laura Rinaldi, and Diego Carnaroglio 8.1 Introduction 155 8.2 Catalysis with Hyphenated and Tandem Techniques 157 8.3 Microwave and Mechanochemical Activation 159 8.4 Microwave and UV Irradiation 162 8.5 Microwave and Ultrasound 164 8.6 Conclusions 166 References 166 Part IV Applications – Organic Reactions 171 9 Applications of Microwave Chemistry in Various Catalyzed Organic Reactions 173 Rick Arneil Desabille Arancon, Antonio Angel Romero, and Rafael Luque 9.1 Introduction 173 9.1.1 Homogeneous Catalysis 175 9.2 Microwave-Assisted Reactions in Organic Solvents 175 9.3 Microwave-Assisted Reactions inWater-Coupling Reactions 179 9.3.1 The Heck Reactions 180 9.3.2 The Suzuki Reaction 186 9.4 Conclusions and Prospects 190 Acknowledgments 190 References 191 10 Microwave-Assisted Solid Acid Catalysis 193 Hyejin Cho, Christian Schäfer, and Béla Török 10.1 Introduction 193 10.2 Microwave-Assisted Clay Catalysis 193 10.3 Zeolites in Microwave Catalysis 199 10.4 Microwave Application of Other Solid Acid Catalysts 205 10.4.1 Heteropoly Acids 205 10.4.2 Acidic Ion-Exchange Resins (Nafion-H, Amberlyst, Dowex) 206 10.4.2.1 Nafion-H 206 10.4.2.2 Amberlyst 207 10.4.2.3 Dowex 208 10.5 Conclusions and Outlook 209 References 209 11 Microwave-Assisted Enzymatic Reactions 213 Takeo Yoshimura, ShigeruMineki, and Shokichi Ohuchi 11.1 Introduction 213 11.2 Synthewave (ProLabo) 217 11.2.1 Lipase 217 11.2.2 Glucosidase 220 11.3 Discover Series (CEM) 220 11.3.1 Lipase (Synthesis, Esterification) 220 11.3.2 Enzymatic Resolution 228 11.3.3 β-Glucosidase, β-Galactosidase 232 11.3.4 Aldolase 233 11.4 Mechanism of the Microwave-Assisted Enzymatic Reaction 233 References 236 Part V Applications – Hydrogenation and Fuel Formation 239 12 Effects of Microwave Activation in Hydrogenation–Dehydrogenation Reactions 241 Leonid M. Kustov 12.1 Introduction 241 12.2 Specific Features of Catalytic Reactions Involving Hydrogen 242 12.3 Hydrogenation Processes under MWConditions 246 12.4 Dehydrogenation 250 12.5 Hydrogen Storage 252 12.6 Hydrogenation of Coal 254 Acknowledgment 254 References 254 13 Hydrogen Evolution from Organic Hydrides throughMicrowave Selective Heating in Heterogeneous Catalytic Systems 259 Satoshi Horikoshi and Nick Serpone 13.1 Situation of Hydrogen Energy and Feature of Stage Methods 259 13.2 Selection of Organic Hydrides as the Hydrogen Carriers 261 13.3 Dehydrogenation of Hydrocarbons with Microwaves in Heterogeneous Catalytic Media 262 13.3.1 Selective Heating by the Microwave Method 262 13.3.2 Dehydrogenation of Tetralin in a Pt/AC Heterogeneous Catalytic Dispersion Subjected to a Microwave Radiation Field 263 13.3.3 Effects of the Tetralin: Pt/AC Ratio on Tetralin Dehydrogenation 264 13.3.4 Dehydrogenation of an Organic Carrier in a Continuous Flow System 266 13.3.5 Dehydrogenation of Methylcyclohexane in a Microwave Fixed-Bed Reactor 269 13.3.6 Simulation Modeling for Microwave Heating of Pt/AC in the Methylcyclohexane Solution 271 13.4 Dehydrogenation of Methane with Microwaves in a Heterogeneous Catalytic System 272 13.5 Problems and Improvements of Microwave-Assisted Heterogeneous Catalysis 273 Acknowledgments 277 References 277 Part VI Applications – Oil Refining 281 14 Microwave-Stimulated Oil and Gas Processing 283 Leonid M. Kustov 14.1 Introduction 283 14.2 Early Publications 283 14.3 Use of Microwave Activation in Catalytic Processes of Gas and Oil Conversions 285 14.3.1 Hydrogen Production 285 14.3.2 CO2 Conversion 286 14.3.3 Synthesis Gas (Syngas) Production 286 14.3.4 Methane Decomposition 287 14.3.5 Methane Steam Reforming 288 14.3.6 Oxidative Coupling of Methane 288 14.3.7 Partial Oxidation and Other Hydrocarbon Conversion Processes 291 14.3.8 Oxidative Dehydrogenation 294 14.3.9 Oil Processing 295 14.4 Prospects for the Use of Microwave Radiation in Oil and Gas Processing 295 Acknowledgment 297 References 297 Part VII Applications – Biomass andWastes 301 15 Algal Biomass Conversion under Microwave Irradiation 303 Shuntaro Tsubaki, Tadaharu Ueda, and Ayumu Onda 15.1 Introduction 303 15.2 Microwave Effect on Hydrothermal Conversion – Analysis Using Biomass Model Compounds 304 15.2.1 Degradation Kinetics of Neutral Sugars under Microwave Heating 304 15.2.2 Effects of Ionic Conduction on Hydrolysis of Disaccharides under Hydrothermal Condition 308 15.3 Hydrolysis of Biomass Using Ionic Conduction of Catalysts 309 15.3.1 Hydrolysis of Starch and Crystalline Cellulose Using Microwave Irradiation and Polyoxometalate Cluster 309 15.3.2 Hydrolysis Fast-Growing Green Macroalgae Using Microwave Irradiation and Polyoxometalate Cluster 311 15.4 Dielectric Property of Algal Hydrocolloids inWater 313 15.4.1 Comparison of Dielectric Property of Aqueous Solution of Hydrocolloids Obtained from Algae and Land Plants 313 15.4.2 The Effects of the Degree of Substitution of Acidic Functional Groups on Dielectric Property of Aqueous Solution of Algal Hydrocolloids 315 15.4.3 The Correlation of Loss Tangent at 2.45 GHz and Other Physical Properties of Sodium Alginates and Carrageenans inWater 316 15.5 Summary and Conclusions 319 Acknowledgments 319 References 319 16 Microwave-Assisted Lignocellulosic Biomass Conversion 323 TomohikoMitani and TakashiWatanabe 16.1 Introduction 323 16.2 Lignocellulosic Biomass Conversion 324 16.3 Multi-mode Continuous Flow Microwave Reactor 325 16.4 Direct-Irradiation Continuous Flow Microwave Reactor 327 16.4.1 Concept of Reactor 327 16.4.2 Designing of Microwave Irradiation Section 327 16.4.3 Prototypes of Reactors 329 16.5 Pilot-Plant-Scale Continuous Flow Microwave Reactor 331 16.5.1 Concept of Reactor 331 16.5.2 Designing of Microwave Irradiation Section 331 16.5.3 Demonstration Experiments of Microwave Pretreatment 333 16.6 Summary and Conclusions 335 References 335 17 Biomass andWaste Valorization under Microwave Activation 337 Leonid M. Kustov 17.1 Introduction 337 17.2 Vegetable Oil and Glycerol Conversion 338 17.3 Conversion of Carbohydrates 339 17.4 Cellulose Conversion 340 17.5 Lignin Processing 342 17.6 Waste and Renewable Raw Material Processing 343 17.7 Carbon Gasification 347 17.8 Prospects for the Use of Microwave Irradiation in the Conversion of Biomass and Renewables 348 Acknowledgment 350 References 350 Part VIII Applications – Environmental Catalysis 355 18 Oxidative and Reductive Catalysts for Environmental Purification Using Microwaves 357 Takenori Hirano 18.1 Introduction 357 18.2 Microwave Heating of Catalyst Oxides Used for Environmental Purification 358 18.3 Microwave-Assisted Catalytic Oxidation of VOCs, Odorants, and Soot 361 18.4 Microwave-Assisted Reduction of NOx and SO2 364 18.5 Conclusions 367 References 367 19 Microwave-/Photo-Driven Photocatalytic Treatment of Wastewaters 369 Satoshi Horikoshi and Nick Serpone 19.1 Situation ofWastewater Treatment by Photocatalytic Classical Methods 369 19.2 Experimental Setup of an Integrated Microwave/Photoreactor System 370 19.3 Microwave-/Photo-Driven PhotocatalyticWastewater Treatment 371 19.3.1 Degradation of Rhodamine B Dye 371 19.3.2 Change of TiO2 Surface Condition under a Microwave Field 376 19.3.3 Specific Nonthermal Microwave Effect(s) in TiO2 Photoassisted Reactions 377 19.3.4 Microwave Frequency Effects on the Photoactivity of TiO2 379 19.3.5 Increase in Radical Species on TiO2 under Microwave Irradiation 380 19.3.6 Microwave Nonthermal Effect(s) as a Key Factor in TiO2 Photoassisted Reactions 382 19.4 Microwave Discharge Electrodeless Lamps (MDELs) 386 19.4.1 The Need for More Efficient UV Light Sources 386 19.4.2 Purification ofWater Using TiO2-Coated MDEL Systems in Natural Disasters 387 19.5 Summary Remarks 389 References 389 Index 393