Fuel cells : technologies for fuel processing

This book covers all aspects of fuel processing: fundamental chemistry, different modes of reforming, catalysts, catalyst deactivation, fuel desulfurization, reaction engineering, novel reforming concepts, thermodynamics, heat and mass transfer issues, system design, recent research and development, etc., which makes it one single source of information for scientists and engineers. It serves as an excellent self-instruction book for those new to fuel cells, and as a comprehensive resource for experts in the area of fuel processing. It can be used as a reference book for advanced level university courses in this area. Chapters written by experts in each area Extensive bibliography supporting each chapter Detailed index Up-to-date diagrams and full colour illustrations Fuel Cells: Technologies for Fuel Processing 3 Copyright 5 Fuel Cells: Technologies for Fuel Processing 6 Editors Biography 528 Contributors 10 Chapter 1 - Introduction to Fuel Processing 420 Clean Energy 12 Fuel Cells 13 Fuel Processors 13 Reforming Modes 14 Thermal Integration of the Fuel Processor and Fuel Cell 15 Challenges for Fuel Cells and Fuel Processors 15 Fuel Flexibility 15 Catalyst 16 Scope of This Book 17 Fundamental Focus 17 Fuel Cell Details 17 References 18 Chapter 2 - Fuel Cells 22 Introduction 22 Fuel Cell Fundamentals 25 Fuel Cell Degradation 28 Fuel Cell Operation 29 Fuel Cell Types 31 Direct Carbon Fuel Cell (DCFC) 32 Polymer Electrolyte Fuel Cell (PEFC) 33 Alkaline Fuel Cell (AFC) 34 Phosphoric Acid Fuel Cell (PAFC) 35 Molten Carbonate Fuel Cell (MCFC) 35 Solid Oxide Fuel Cell (SOFC) 36 References 79 Chapter 3 - Fuels for Fuel Cells 40 Introduction 40 Fossil Fuels 41 Gaseous Fuels 41 Natural Gas 41 Liquefied Petroleum Gas 43 Gasoline 43 Automotive Gasoline 46 Aviation Gasoline 46 Gasohol 47 Octane Rating 47 Additives in Gasoline 48 Antioxidants 48 Corrosion Inhibitors 48 Demulsifiers 48 Anti-Icing 48 Dyes and Markers 48 Drag Reducers 48 Oxygenates (Fuel Additives) 49 Adulteration 49 Kerosene 49 Diesel Fuel 51 Jet Fuels 52 Fuel Oil 52 Oxygenated Fuels 54 Methanol 54 Ethanol 56 Dimethyl Ether 56 Biodiesel 57 References 58 Chapter 4 - Steam Reforming for Fuel Cells 60 Routes to Hydrogen 297 Steam Reforming of Natural Gas 61 Thermodynamics 61 Tubular Reformer 61 Nickel-Based Catalysts 203 Support 63 Promoters/Alloys 64 Catalyst Particles 64 Activation 64 Nickel Dispersion 65 Sintering 65 Non-Nickel Catalysts 65 Non-Metal Catalysts 66 Ceria 66 Carbides 66 Non-Catalytic Reforming 66 Mechanism and Kinetics 66 Sulfur Poisoning 68 Carbon Formation 68 Steam Reforming of Other Feedstocks 70 Liquid Hydrocarbons 70 4.3.1.1 Carbon Formation 70 Effect of Promoters on Carbon Formation 71 Temperature Effects 71 Alcohols 72 Methanol 72 Ethanol 502 Other Oxygenates 73 Hydrogen Production 73 Industrial Hydrogen Manufacture by Steam Reforming 73 Heat Recovery 74 Steam Reforming for Fuel Cell Plants 74 Process Configuration for Fuel Cell Applications: SOFC 75 Process Configuration for Fuel Cell Applications: PEMFC 75 Comparison of SOFC and PEMFC processes 77 Conclusions 79 References 79 Chapter 5 - Catalytic Partial Oxidation 540 Introduction 85 Thermodynamics 86 Heat of Reaction 32 Effect of Temperature 87 Effect of O/C Ratio 89 Reaction Mechanisms and Kinetics 91 Reaction Mechanisms 91 Direct Mechanism 93 Indirect Mechanism 95 Effect of Space Velocity 96 Effect of Catalyst Oxidation State 98 Mechanism for Methanol 99 Kinetic Studies 65 Summary for Mechanisms and Kinetics 102 Light Hydrocarbons 103 Methane 103 Base Metal Catalysts 104 Modified Alumina Supports 104 Basic Supports 105 Basic Promoters 106 Oxygen-Conducting Supports 107 Noble Metal Catalysts 109 Rhodium and Platinum Catalysts 110 Structured Supports 111 Other Support Systems 224 Bimetallic Catalysts 114 Ethane, Propane, and Butane 115 Summary for Light Hydrocarbons 117 Higher Hydrocarbons 31 Base Metal Catalysts 117 Promoters 117 Substituted Oxides and Oxygen-Conducting Supports 117 Substituted Oxides on Oxygen-Conducting Supports 405 Noble Metal Catalysts 450 Promoters 124 Supports 125 Substitution into Oxide Structures 127 Summary of Higher Hydrocarbons 127 Oxygenated Hydrocarbons 127 Alcohols 127 Dimethyl Ether (DME) 130 Biodiesel 130 Summary of Oxygenated Hydrocarbons 131 Future Development and Applications 131 Substituted Oxides on Oxygen-Conducting Supports 131 Multistaged Reactor 132 Multiple Oxygen Feed Locations 132 Multiple Catalyst Formulations 132 Field-assisted CPOX 133 CPOX with Recycle 133 References 134 Chapter 6 - Oxidative Steam Reforming 140 Introduction 141 Thermodynamics 142 Contributing Reactions 142 Effect of Temperature 143 Effect of Oxidant to Fuel ratio – O/C and S/C 203 Increasing O/C Ratio 145 Increasing S/C ratio 145 Autothermal Operation 146 Reaction Enthalpy 282 Effect of Pressure 148 Mechanism 149 Combustion-Reforming Mechanism 149 Effect of O/C and H2O/C Ratios 302 Pyrolysis-reforming Mechanism 153 Decomposition and Reforming Mechanism for Oxygenates 154 Kinetics 155 Hydrocarbons 155 Combination of Individual Reactions Approach 155 Fundamental Approach 157 Methanol 158 Catalytic OSR of Hydrocarbons 534 Natural Gas/Methane 159 Non-Precious Metals 160 Nickel 160 Effect of precursor 161 Promoters 161 Noble metals 142 Non-noble metals 143 Supports 166 Alumina 203 Basic supports 145 Oxygen-conducting supports 145 Other Non-Precious Metals 168 Cobalt 168 Iron and Copper 168 Noble Metals 169 Rhodium 169 Other Noble Metals 171 Platinum 171 Ruthenium 172 C2–C6 Hydrocarbons 174 Catalysts 174 Hydrotalcites 174 Transportation Fuels 175 Nickel-Based Catalysts 176 Alumina 176 Oxygen-conducting supports 177 Perovskites 178 Noble Metals 181 Rhodium 181 Other Noble Metals 183 Mixed Metal Oxides (substituted oxides) 184 Perovskites 184 Pyrochlores 185 Oxygenated Compounds 186 Methanol 186 Copper-based Catalysts 186 Promoters for Copper 186 Effect of synthesis method 187 Ethanol 187 Biodiesel 190 Future Work 190 Staged Reactor Configuration 190 Bimetallic Substituted Oxides 191 References 192 Chapter 7 -Dry (CO2) Reforming 202 Introduction 203 Thermodynamics 203 Heat of Reaction 236 Equilibrium Conversion 203 Effect of CO2/Fuel Ratio 203 Effect of Temperature and Pressure 204 Catalysts for Dry Reforming of Methane 205 Ni-Based Catalysts 205 Preparation Methods and Ni Particle Size 205 Basic Promoters and Supports 209 Perovskite-Type Catalysts 210 Nanocomposite Supports 211 Co-Based Catalysts 212 Noble Metal Catalysts 212 Noble-Metal Promoted Ni Catalysts 382 Metal Carbide Catalysts 214 Reaction Mechanism and Kinetics of Dry Reforming of Methane 215 Ni-Only Catalyst 215 Rare Earth Metals Supported Ni Catalyst 216 Kinetics 217 Dry Reforming of Ethane 218 Dry Reforming of Propane 127 Catalysts 219 Reaction Mechanism and Kinetics 220 Reforming of Higher Hydrocarbons 221 Dry Reforming of Oxygenated Hydrocarbons 221 Ethanol 221 Dimethyl Ether 223 Glycerol 224 Summary 224 References 79 Chapter 8 -Plasma Reforming for H2-Rich Synthesis Gas 234 Introduction 235 What Is Plasma? 236 Types of Plasmas Used in Fuel Processing Applications 236 Arc Plasmas 87 Non-Thermal Gliding Arc Plasmas 237 Microwave and Radio Frequency Plasma Discharges 238 Dielectric Barrier Discharge 240 Continuous and Pulsed Corona 241 Plasma as an Alternative to Traditional Catalysts in Fuel Reforming 242 Thermal versus Non-thermal Mechanisms of Plasma Catalysis 243 Non-thermal Plasma-Induced Mechanisms of Ignition and Stabilization of Flames 244 Effect of Excited Species on Subthreshold Ignition in H2–O2 Mixtures 244 Effect of Ions on Subthreshold Ignition in H2–O2 Mixtures 245 Effect of Radicals and Other Long-Lived Species on Subthreshold Ignition 433 Effect of Plasma Active Species on Hydrogen-Rich Syngas Production Systems 66 Some Plasma Catalysis Mechanisms for Methane Conversion 246 Direct Decomposition (Pyrolysis) 246 Partial Oxidation 247 Advantages of Plasma Catalysis in Fuel Reforming Systems 248 Rapid Start-Up 438 Sulfur Tolerant Process 248 Reduced Carbon By-Product Formation 248 Small and Compact Systems 249 Possibility of Combining Desulfurization and Reforming 249 Plasma Reforming of Methane 250 Plasma-Assisted Partial Oxidation 250 Plasma-Assisted Steam-Reforming 252 Plasma-Assisted Carbon Dioxide (Dry) Reforming 253 Plasma-Assisted Pyrolysis 253 Plasma Reforming of Liquid Hydrocarbons 218 Plasma-Assisted Partial Oxidation of Diesel Fuel and Its Surrogates into Synthesis Gas 254 Plasma-Assisted Reforming of Ethanol 257 Plasma-Assisted Oxidative Steam Reforming of Various Liquid Hydrocarbon Fuels 257 Combined Plasma-Catalytic Reforming of Hydrocarbon Fuels into Hydrogen-Rich Synthesis Gas 288 Plasma-Catalytic Two-Stage Configuration for Hydrocarbon Reforming 263 Plasma-Catalytic Single-Stage Configuration for Hydrocarbon Reforming 264 Conclusions and Future Trends 265 References 266 Chapter 9 -Nonconventional Reforming Methods 40 Scope of the Chapter 373 Decomposition of Hydrocarbons 273 Thermodynamics 273 Mechanism 274 Catalysts 274 Reactor Design 275 Supercritical Reforming 28 Thermodynamics and Mechanism 278 Metal Reactor Wall as a Catalyst 281 Catalysts 282 Non-catalytic Thermal Reforming in Porous Media 283 Types and Reaction Mechanism 283 Important Parameters in Non-catalytic Thermal Reforming 284 Porous Media Bed Materials 284 Reactor Design for Reforming in Porous Media 285 Reforming of Various Fuels in Porous Media 287 Radio Frequency (RF)-Assisted Reforming 287 Pre-reforming 288 Catalyst and Reactor Configurations 290 References 291 Chapter - 10 Deactivation of Reforming Catalysts 296 Scope of This Chapter 297 Introduction – General Mechanisms for Fuel Reforming 297 Thermally Induced Deactivation 298 Minimizing Thermal Deactivation 298 Thermally Stable Supports 298 Incorporating the Metal into a Stable Oxide 299 Effect of Reactor Temperature Gradients 145 Effect of Deactivation on Temperature Gradients 300 Effect of Deactivation on Reformate Composition 300 Sulfur Poisoning 301 Thermodynamics 302 Metal Sulfide Formation 302 Effect of Temperature 302 Effect of Temperature and Sulfur Concentration 302 Effect of Temperature 302 Effect of Sulfur Concentration 303 Resistance to Sulfur Poisoning 383 Oxygen Mobility 304 Regeneration of Sulfur-Poisoned Catalysts 305 Regeneration in Hydrogen 341 Regeneration in Oxygen 306 Regeneration in Steam 308 Sulfur-Tolerant Catalysts 308 Sulfide-Forming Metals/Sorbents 309 Coke/Carbon Deposition 310 Thermodynamics of Elemental Carbon Formation 310 Effect of Aromatics 311 Minimizing Carbon Deposition 312 Effect of S/C Ratio 312 Regeneration of Catalysts Deactivated by Carbon Deposition 313 Types of Carbon 313 Characterization of Carbon Deposits 448 Temperature-Programmed Oxidation 314 Temperature-Programmed Hydrogenation 315 Comparison of TPO and TPH on the Same Catalyst 316 Computational Modeling of Carbon Deposition 317 Kinetics of The Deactivation Processes 317 Modeling of Poisoning 318 Modeling of Carbon Deposition 319 Modeling of Sintering 320 Conclusions 265 References 321 Chapter 11 - Desulfurization for Fuel Cells 328 Introduction 329 Scope 25 Gas Phase Desulfurization Upstream of Reformer 331 Natural Gas and Liquefied Petroleum Gas (LPG) 331 Background 331 Adsorption 333 Desirable Sorbent Characteristics 333 Conventional Sorbents 333 Recent Sorbent Development Research 334 Application to Fuel Cell Systems 337 Selective Oxidation Followed by Adsorption 379 Gasoline, Jet Fuel, and Diesel 338 Background 338 Hydrodesulfurization (HDS) 338 Reactive Adsorption 340 Process Development 214 Sorbent Preparation and Performance 104 Mechanism 341 Application to Fuel Cell Systems 341 Adsorption 342 Nickel-based Sorbents 342 Application to Fuel Cell Systems 343 Liquid Phase Desulfurization Upstream of Reformer 343 Adsorption 111 Activated Carbon and Polarity-Based Sorbents 344 Sorbents Based on Sulfur–Metal (S–M) Interaction 347 Sorbents Based on π-Complexation 348 Application to Fuel Cell Systems 312 Oxidation-Assisted Adsorption 351 Background 351 Examples of the Use of Air (Oxygen) as Oxidant 351 Application to Fuel Cell Systems 353 Syngas Desulfurization Downstream of Reformer or Gasifier 353 Metal Oxide Sorbents 353 Principle 353 Metal Oxide Sorbents Employed in the Past 355 Recent Metal Oxide Sorbent Development Efforts 356 Zinc Oxide-based Sorbents 357 Cerium Oxide-based Sorbents 358 Selective Catalytic Oxidation of H2S 359 Application to Fuel Cell Systems 360 Integration of Sulfur Removal 361 Conclusions and Future Directions 362 References 364 Chapter 12 - Syngas Conditioning 372 Introduction 373 Water Gas Shift 236 Thermodynamics 374 High-Temperature WGS Catalysts 375 Low-Temperature WGS Catalysts (LTS) 43 Sulfur-Tolerant WGS Catalysts 377 Precious Metal-Based WGS Catalysts 377 Ceria and Titania-Supported Catalysts 378 Mechanism 378 Non-reducible Supports 379 Deactivation Mechanisms 379 Palladium–Zinc-Based Catalysts 245 Au-Based Catalysts 381 Reactor Design 382 Summary and Outlook 383 Preferential Oxidation (PrOX) 384 Thermodynamics 66 General Considerations 386 PrOX Catalysts 437 Pt Catalysts 387 Ru-, Rh-, Pd-, and Ir-Based Catalysts 389 Au Catalysts 391 Catalyst Preparation 161 Catalyst Performance 392 Transition Metal Oxide Catalysts 395 Practical Application in Small Fuel Processors 168 Summary 400 Selective Catalytic Methanation of CO (SMET) 401 General Considerations 401 Catalysts for Selective Methanation (SMET) 401 Ru-Based Catalysts 402 Ni-Based Catalysts 405 Other Catalysts 407 High-Throughput Synthesis and Testing of Selective Methanation Catalysts 408 Engineering-Based Approaches to SMET 409 Thermally Differential Methanation 409 Two-Stage Methanation 409 CO2 Scrubbing in Combination with Methanation 409 Membrane Reactor Combined with Methanation 409 Conclusions 176 References 410 Chapter 13 - Direct Reforming Fuel Cells 420 Introduction 421 Requirements for Internal Reforming Anodes 421 Development Trends for SOFC Anodes 143 Thermodynamics 423 Benefits of Internal Reforming 423 Thermodynamic Considerations 423 Energy Balances Around the Stacks for a 250 kW SOFC Plant 424 Thermodynamics of Other Fuels than Methane 426 Carbon Formation 283 Pyrolysis 428 Graphite Formation 243 Whisker (Carbon Nanotubes) Formation 428 Experimental Studies on Low O/C Operation 430 Carbon Formation with Methane as Fuel 149 Carbon Formation with Biogas as Fuel or During CO2 Reforming 433 Carbon Formation with Higher Hydrocarbons as Fuel 433 Carbon Formation in Tar Containing Gases 434 Carbon Formation with Alcohols as Fuel 246 Carbon Formation on Copper-Based Anodes 436 Ammonia as SOFC Fuel 436 Kinetics of Steam Reforming on Nickel-YSZ Anodes 437 Importance of Kinetics and Comparison with Ordinary Steam Reforming 437 Experimentally Determined Kinetics 438 The Optimum Reforming Rate 441 Poisons for SOFC Anodes 442 Sulfur 442 Thermodynamics of Sulfur Poisoning 442 Impact of Sulfur with Hydrogen as Fuel 443 Impact of Sulfur with Hydrogen and Carbon Monoxide as Fuel 446 Impact of Sulfur with Coal Gas as Fuel 446 Impact of Sulfur with Synthesis Gas from Biomass Gasification 447 Impact of Sulfur with Methane-Containing Fuel 447 Impact of Sulfur with Biogas as Fuel 447 Other SOFC Anode Poisons 448 Chlorine 449 Phosphorus 450 Arsenic 451 Selenium 452 Antimony 452 Cadmium 452 Zinc and mercury 452 Tars 452 Synergistic Effects 452 Summing Up: Impact of Poisons on Nickel-based SOFC Anodes 453 Concluding Remarks 453 References 454 Chapter 14 - Reactor Design for Fuel Processing 462 Design Requirements of the Fuel Processing Unit 540 Natural Gas and Liquefied Petroleum Gas 236 Steam Reforming 464 Partial Oxidation 466 Oxidative Steam Reforming 467 Gasoline and Diesel 471 Evaporation and Mixing 241 Steam Reforming 302 Partial Oxidation 472 Oxidative Steam Reforming 473 Oxygenated Hydrocarbons 473 Methanol 474 Ethanol 475 Design Requirements of WGS Unit 476 Design Requirements of Carbon Monoxide Removal Unit 423 Preferential CO Oxidation (PrOX) 478 Selective CO Methanation 479 Design Requirements of Desulfurization Unit 480 Types of Reactors Used in Fuel Processing 481 Fixed-Bed Reactors 482 Monolithic Reactors 484 Microchannel Reactors 487 Foam Reactors and Wire-Gauzes 490 Foam Reactors 490 Wire-Gauzes 493 Integrated Reactors 494 Heat-Exchanger Reactors 494 Membrane Reactors 499 Modeling and Design of Fuel Processing Reactors 541 Fixed-Bed Reactors 502 Wall-Coated Structured Reactors 508 Membrane Reactors 513 Packed-Bed Membrane Reactors 513 Catalytic Membrane Reactors 514 Acknowledgments 518 References 192 Chapter 15 - Balance of Plant 528 Introduction 528 Fuel, Air, and Water Management 528 Liquid Pumps 529 Fuel Pump 529 Water Pump 530 Air Movers 530 Fuel Injection System 149 Heat Management Systems 533 Heat Exchangers 377 Insulation 46 Other Components 534 Sensors 534 Controls 535 Start-up Power 536 Conclusion and Future Directions 536 References 364 Appendix A - Thermodynamic Data for Selected Chemicals 538 Appendix B - Definitions 540 Space Time 540 Space Velocity 41 Weight Hourly Space Velocity 540 Gas Hourly Space Velocity (GHSV) 541 Volume Hourly Space Velocity (VHSV) 541 Fuel Conversion 541 Product Yield 542 Product Selectivity 543 Turnover Frequency 543 Carbon Formation 544 Oxygen-to-Carbon Ratio 544 Equivalence Ratio 544 Steam-to-Carbon Ratio 545 Recycle Ratio 545 Reformer Efficiency 545 Fuel Cell Efficiency 546 Start-up Time 546 Appendix C - Acronyms 528 Index 550 A 550 B 550 C 551 D 552 E 553 F 554 G 555 H 555 I 556 J 556 K 557 L 557 M 557 N 558 O 559 P 560 R 562 S 564 T 566 V 566 W 566 Z 566 Fuel Cells: Technologies for Fuel Processing provides an overview of the most important aspects of fuel reforming to the generally interested reader, researcher, technologist, teacher, student, or engineer. The topics covered include all aspects of fuel reforming: fundamental chemistry, different modes of reforming, catalysts, catalyst deactivation, fuel desulfurization, reaction engineering, novel reforming concepts, thermodynamics, heat and mass transfer issues, system design, and recent research and development. While no attempt is made to describe the fuel cell itself, there is sufficient description of the fuel cell to show how it affects the fuel reformer. By focusing on the fundamentals, this book aims to be a source of information now and in the future. By avoiding time-sensitive information/analysis (e.g., economics) it serves as a single source of information for scientists and engineers in fuel processing technology. The material is presented in such a way that this book will serve as a reference for graduate level courses, fuel cell developers, and fuel cell researchers. Chapters written by experts in each area Extensive bibliography supporting each chapter Detailed index Up-to-date diagrams and full colour illustrations This book covers all aspects of fuel processing: fundamental chemistry, different modes of reforming, catalysts, catalyst deactivation, fuel desulfurization, reaction engineering, novel reforming concepts, thermodynamics, heat and mass transfer issues, system design, recent research and development, etc., which makes it one single source of information for scientists and engineers. It serves as an excellent self-instruction book for those new to fuel cells, and as a comprehensive resource for experts in the area of fuel processing. It can be used as a reference book for advanced level university courses in this area. Chapters written by experts in each area Extensive bibliography supporting each chapter Detailed index Up-to-date diagrams and full colourillustrations Associated webpages with links to other relevant material Numerical problems with solutions.