Microwave Chemical and Materials Processing: A Tutorial

Preface
Contents
About the Authors
1 Microwave as a Heat Source
	1.1 Applications of Microwaves
	1.2 Some Applications of Microwave Heating
	1.3 Fields of Microwave Chemistry and Materials Processing
	1.4 Overview of Microwave Chemistry
	1.5 Overview of Microwave Usage in Materials Processing
	1.6 Overview of Microwave Usages in Other Sciences
	1.7 Coffee Break 1: Raytheon Corporation
	References
2 The Nature of Heat
	2.1 What is Heat?
	2.2 Historical Aspects of Heat
	2.3 Heat Versus Temperature
	2.4 Thermodynamics
	2.5 Heat Transfer
	2.6 Coffee Break 2: Background on the Relationship Between Microwaves and Foods
	References
3 Electromagnetic Fields and Electromagnetic Waves
	3.1 The Nature of Electromagnetic Fields and Electromagnetic Waves
	3.2 History of Electromagnetic Waves
	3.3 The Nature of Microwaves
	3.4 Maxwell’s Equations
	3.5 Microwaves as Electromagnetic Waves
		3.5.1 History of the Name “Microwave”
		3.5.2 Differences in the Features of Communication by Light and Microwaves
		3.5.3 Responses of Substances to Electromagnetic Waves
	3.6 Coffee Break 3: Frequencies Used for Food Heating
	References
4 Microwave Heating
	4.1 Types of Microwave Heating
		4.1.1 Overview of Microwave Heating
		4.1.2 Microwave Heating of Substrates in Solutions
		4.1.3 Microwave Heating of a Solid Substance
		4.1.4 Difference(s) Between Microwave Heating and Conventional Heating
		4.1.5 Features of Microwave Heating Relative to Other Heating Methods
	4.2 Direct Heating of Materials
		4.2.1 Internal Heating and External Heating
		4.2.2 Precise Temperature Measurement by Using Microwave Internal Heating
		4.2.3 Applications of Internal Heating
	4.3 Selective Heating
		4.3.1 Fundamental Selective Heating
		4.3.2 Application of Microwave Selective Heating
	4.4 Hot spots or Local Heating
		4.4.1 What is a Hot spot?
		4.4.2 Hot spot Formation in Catalyzed Reactions—Background
		4.4.3 Mechanism(s) of Formation of Hot spots
		4.4.4 Control of the Occurrence of Hot spots
	4.5 Hot spots in Microwave Sintering
		4.5.1 Background for Hot spots in Solid Processing
		4.5.2 Principles and Control of Occurrence of Hot spots in Samples
		4.5.3 Principles and Control of Hot spots and Electromagnetic Waves
	4.6 Superheating of Liquids
		4.6.1 What is Superheating?
		4.6.2 Mechanistic Stages of Superheating
		4.6.3 Applications of Superheating to Chemical Reactions
	4.7 Coffee Break 4: What is a Microwave Oven?
	References
5 Physics of Microwave Heating
	5.1 Dielectric Properties
	5.2 Permeability
	5.3 Measurement of Complex Permittivity and Complex Permeability of Materials
		5.3.1 Non-resonant Methods
		5.3.2 The Transmission/Reflection Line Method
		5.3.3 The Free-Space Method
		5.3.4 The Open-Ended Coaxial Probe Method
		5.3.5 Resonant Methods
		5.3.6 Measurements of Dielectric Factors Using Microwave Irradiation
		5.3.7 Advice for Beginners and Students Who Measure Permittivity
	5.4 Adjustment of the Impedance
		5.4.1 What is Meant by Impedance in the Present Context?
		5.4.2 Impedance in Equipment and Sample
	5.5 Microwave Heating Mechanism
		5.5.1 Phenomena of Dipole Rotation on Application of Microwaves
		5.5.2 Relationship of Microwave Heating Behavior with the Materials’ Physical Properties
		5.5.3 Conduction Loss Heating (Eddy Current Loss and Joule Loss)
		5.5.4 Dielectric Heating and Magnetic Loss Heating—An Introduction
		5.5.5 Dielectric Heating—Energy Loss in a Microwave Field
		5.5.6 Magnetic Loss
	5.6 Penetration Depth and Skin Depth
		5.6.1 What Are They?
		5.6.2 Penetration Depth
		5.6.3 Penetration Depths of 915-MHz, 2.45-GHz, and 5.80-GHz Microwaves
		5.6.4 Skin Depth
	5.7 Frequency Effect
		5.7.1 Is It Possible to Use Various Frequencies?
		5.7.2 Historical Overview of Microwave Frequency Effects in Chemical Reactions and Sintering
		5.7.3 Microwave Chemical Equipment for 0.915, 2.45, and 5.80 GHz Frequencies
		5.7.4 Frequency Effects for the Common Solvents
		5.7.5 Rates of Temperature Increase of Common Solvents
	5.8 Frequency Effects in Organic Synthesis
		5.8.1 Application to a Diels–Alder Reaction
		5.8.2 Synthesis of a Room-Temperature Ionic Liquid (RTIL)
		5.8.3 Synthesis of Gemini Surfactants Under 915-MHz Microwave Irradiation
		5.8.4 Frequency Effects in Nanoparticle Synthesis
	5.9 Summary Remarks on the Frequency Effect
	5.10 Electromagnetic and Thermodynamics Simulations
		5.10.1 Transmission Modes
		5.10.2 Coffee Break 5: Using the Microwave Oven
	References
6 Engineering of Microwave Heating
	6.1 Components in Microwave Heating Equipment
	6.2 Microwave Generators
		6.2.1 Vacuum Tubes as Microwave Sources
		6.2.2 Magnetron Generation of Microwaves
		6.2.3 Klystron and TWT Generators
		6.2.4 Semiconductor Generation of Microwaves
	6.3 Waveguides, Isolators, Power Monitors, Tuners, Iris, and Short Plungers
		6.3.1 Waveguides
		6.3.2 Coaxial Cables
		6.3.3 Isolators
		6.3.4 Power Monitors
		6.3.5 The Tuner
		6.3.6 Iris and Short Plungers
	6.4 Single-Mode Versus Multimode Applicators
		6.4.1 What is an Applicator?
		6.4.2 Single-Mode Applicator
		6.4.3 Multimode Applicator
		6.4.4 Mode Stirrer
	6.5 Antenna
		6.5.1 Antenna Theory
		6.5.2 Types of Antennas
		6.5.3 Antennas Versus Applicators
		6.5.4 Uniform and Nonuniform Heating of Materials with Antennas
	6.6 Temperature Measurements
		6.6.1 Thermometers
		6.6.2 Temperature Measurement in a Solution Sample
		6.6.3 Temperature Measurements in Solid Samples
	6.7 Prevention of Microwave Leakages
		6.7.1 Choke Trap
		6.7.2 Prevention of Microwave Leakages at the Sample Observation Window
	6.8 Visualization of Microwaves
	6.9 Coffee Break 6: Browning and Crisping in a Microwave Oven
	References
7 Microwave Chemistry in Liquid Media
	7.1 Effective Microwave Heating in Chemistry
	7.2 Reactors
	7.3 Heat Insulators
		7.3.1 Differences in Heat Insulation for Classical Chemistry and Microwave Chemistry
		7.3.2 Heat Insulators
		7.3.3 Dewar-Like Double-Walled Insulated Reactor
	7.4 Effects of Samples in a Microwave-Assisted Process
	7.5 Temperature Control by Cooling
	7.6 Microwave Chemical Synthesis Equipment and Its Development
	7.7 Coffee Break 7: Microwaves and Steam—A Unique Hybrid Cooking System
	References
8 Microwave Materials Processing in Solid Media
	8.1 Effective Microwave Heating in Materials Processing
	8.2 Useful Aspects in Carrying Out Uniform Heating
		8.2.1 Heat Transfer
		8.2.2 Conduction
		8.2.3 Convection
		8.2.4 Radiation
		8.2.5 Heat Insulation
		8.2.6 Isothermal Adiabatic Wall
	8.3 Microwave Heating of Carbonaceous Substrates
		8.3.1 Microwave Heating of Carbon-Related Materials
		8.3.2 Mechanism of Microwave Heating of Solid Carbon
	8.4 Microwave Heating of Solid Samples
		8.4.1 Heating Efficiency of Materials
		8.4.2 Dielectric Heating
		8.4.3 Magnetic Field Heating
		8.4.4 Joule Heating
	8.5 Heating of Materials Usually Unsuitable for Microwave Heating
	8.6 Hybrid Microwave Heating with Susceptors
	8.7 Question: Can Microwaves Heat Metals?
	8.8 Microwave Sintering Equipment
	8.9 Coffee Break 8: Microwave Food Processing Industry
	References
9 Microwave-Assisted Chemistry
	9.1 Microwave-Assisted Organic Synthesis
		9.1.1 Heat Sources in Organic Synthesis
		9.1.2 Overview of Microwave-Assisted Organic Syntheses
		9.1.3 Microwave-Assisted Organic Synthesis (MAOS) in Green Chemistry
		9.1.4 Solvent-Free Microwave-Assisted Organic Syntheses
		9.1.5 Water Solvent System
		9.1.6 Labeling by an Isotope Element
		9.1.7 Removal of Dissolved Oxygen
		9.1.8 Scaling up of Microwave-Assisted Organic Syntheses (MAOS)
	9.2 Microwave-Assisted Polymerization
		9.2.1 Overview of Microwave-Assisted Polymer Syntheses
		9.2.2 The Advantage of Microwaves in Macromolecular Syntheses
		9.2.3 Scale-Up of Polymer Syntheses
	9.3 Enzymatic Reactions
		9.3.1 Situation of Microwave Heating in Biomaterials
		9.3.2 Microwave Effect in Enzymatic Reactions
		9.3.3 Some Relevant Issues Regarding the Equipment Used in Enzymatic Reactions
		9.3.4 Microwave-Accelerated Meat Aging Device (Aging Booster)
	9.4 Summary of Data in Microwave-Assisted Enzymatic Reactions
	9.5 Coffee Break 9: Can Microwaves Affect Plant Growth?
	References
10 Microwave-Assisted Catalytic Reactions (MACR)
	10.1 Microwave-Assisted Catalytic Reactions (MACR)
		10.1.1 History of MACR
		10.1.2 Effectiveness of Selective Catalyst Heating Using MHMTE Conditions
	10.2 Gaseous Reactions with Solid Catalysts
		10.2.1 Decomposition of Polluting Gases
	10.3 Green Hydrogen
		10.3.1 Applications Directed Toward Hydrogen Storage
		10.3.2 Application to Hydrogen Generation from Seawater
	10.4 Features of MHMTE
		10.4.1 Is MHMTE Effective Even with Solid Catalysts?
		10.4.2 Is MHMTE Versatile for All Solid Catalysts?
	10.5 Discharge on MHMTE
		10.5.1 Discharge Issues and It’s Suppression
	10.6 Microwave/Photo-Driven Catalytic Reaction
		10.6.1 Microwave/Photo-Driven Catalytic Treatment of Wastewaters
	10.7 Microwave Synthesis of Solid Catalysts
		10.7.1 Synthesis of Metal Catalysts on Carbonaceous Material Supports
		10.7.2 Catalyst Synthesis Using Features of Microwave Heating
	10.8 Thermal and Nonthermal Roles of Microwaves in Catalytic Reactions
	10.9 Coffee Break 10: Future of Microwave Processing of Foods
	References
11 Materials Processing by Microwave Heating
	11.1 Processing of Solid-State Materials
		11.1.1 Sintering and Drying of Ceramics
		11.1.2 Ceramics with Structural Features, Heated by Microwave Sintering
		11.1.3 Metallic Substrates
		11.1.4 Why Microwave Sintering?
		11.1.5 Drying of Monolithic Refractory Substrates
		11.1.6 Drying of Transparent Conductive Films and Nano-Inks
		11.1.7 Features of Microwaves in Syntheses
		11.1.8 Control of Magnetic Properties of Spinel Oxide by Microwave Magnetic Field Irradiation
		11.1.9 Minerals Processing
		11.1.10 In Situ Measurement During Microwave Heating of Solid-State Materials
	11.2 Microwave Processing in the Liquid State
		11.2.1 Syntheses in Liquid Media
		11.2.2 Nanoparticle Synthesis in Liquid Media
		11.2.3 Specific Microwave Synthesis
		11.2.4 Nanoparticle Syntheses in Continuous-Flow Reactors
		11.2.5 Compendium of Microwave-Assisted Nanoparticle Syntheses
	11.3 High-Quality Microwave Process to Cure Adhesives and Vulcanize Tire Rubber
		11.3.1 Curing of Adhesives
		11.3.2 Vulcanization of Tire Rubber
	11.4 Coffee Break 10: Future Developments in Microwave Ovens
	References
Appendix A Microwave Chemical and Materials Processing
A. Tutorial