Contents

Cover

Title page

Copyright page

Preface

Part 1: Catalytic and Electrochemical Hydrogen Production

Chapter 1: Hydrogen Production from Oxygenated Hydrocarbons: Review of Catalyst Development, Reaction Mechanism and Reactor Modeling
1. 1.1 Introduction
2. 1.2 Catalyst Development for the Steam Reforming Process
3. 1.3 Kinetics and Reaction Mechanism for Steam Reforming of Oxygenated Hydrocarbons
4. 1.4 Reactor Modeling and Simulation in Steam Reforming of Oxygenated Hydrocarbons
5. References
Chapter 2: Ammonia Decomposition for Decentralized Hydrogen Production in Microchannel Reactors: Experiments and CFD Simulations
1. 2.1 Introduction
2. 2.2 Ammonia Decomposition for Hydrogen Production
3. 2.3 Ammonia-Fueled Microchannel Reactors for Hydrogen Production: Experiments
4. 2.4 CFD Simulation of Hydrogen Production in Ammonia-Fueled Microchannel Reactors
5. 2.5 Summary
6. Acknowledgments
7. References
Chapter 3: Hydrogen Production with Membrane Systems
1. 3.1 Introduction
2. 3.2 Pd-Based Membranes
3. 3.3 Fuel Reforming in Membrane Reactors for Hydrogen Production
4. 3.4 Thermodynamic and Economic Analysis of Fluidized Bed Membrane Reactors for Methane Reforming
5. 3.5 Conclusions
6. Acknowledgments
7. References
Chapter 4: Catalytic Hydrogen Production from Bioethanol
1. 4.1 Introduction
2. 4.2 Production Technology Overview
3. 4.3 Catalyst Overview
4. 4.4 Catalyst Optimization Strategies
5. 4.5 Reaction Mechanism and Kinetic Studies
6. 4.6 Computational Approaches
7. 4.7 Economic Considerations
8. 4.8 Future Development Directions
9. Acknowledgment
10. References
Chapter 5: Hydrogen Generation from the Hydrolysis of Ammonia Borane Using Transition Metal Nanoparticles as Catalyst
1. 5.1 Introduction
2. 5.2 Transition Metal Nanoparticles in Catalysis
3. 5.3 Preparation, Stabilization and Characterization of Metal Nanoparticles
4. 5.4 Transition Metal Nanoparticles in Hydrogen Generation from the Hydrolysis of Ammonia Borane
5. 5.5 Durability of Catalysts in Hydrolysis of Ammonia Borane
6. 5.6 Conclusion
7. References
Chapter 6: Hydrogen Production by Water Electrolysis
1. 6.1 Historical Aspects of Water Electrolysis
2. 6.2 Fundamentals of Electrolysis
3. 6.3 Modern Status of Electrolysis
4. 6.4 Perspectives of Hydrogen Production by Electrolysis
5. Acknowledgment
6. References
Chapter 7: Electrochemical Hydrogen Production from SO₂ and Water in a SDE Electrolyzer
1. 7.1 Introduction
2. 7.2 Membrane Characterization
3. 7.3 MEA Characterization
4. 7.4 Effect of Anode Impurities
5. 7.5 High Temperature SO₂ Electrolysis
6. 7.6 Conclusion
7. References

Part 2: Bio Hydrogen Production

Chapter 8: Biomass Fast Pyrolysis for Hydrogen Production from Bio-Oil
1. 8.1 Introduction
2. 8.2 Biomass Pyrolysis to Produce Bio-Oils
3. 8.3 Bio–Oil Reforming Processes
4. 8.4 Future Prospects
5. References
Chapter 9: Production of a Clean Hydrogen-Rich Gas by the Staged Gasification of Biomass and Plastic Waste
1. 9.1 Introduction
2. 9.2 Chemistry of Gasification
3. 9.3 Tar Cracking and H₂ Production
4. 9.4 Staged Gasification
5. 9.5 Experimental Results and Discussion
6. 9.6 Conclusions
7. References
Chapter 10: Enhancement of Bio-Hydrogen Production Technologies by Sulphate-Reducing Bacteria
1. 10.1 Introduction
2. 10.2 Sulphate-Reducing Bacteria for H₂ Production
3. 10.3 Mathematical Modeling of the SR Fermentation
4. 10.4 Bifurcation Analysis
5. 10.5 Process Control Strategies
6. 10.6 Conclusions
7. Acknowledgment
8. Nomenclature
9. References
Chapter 11: Microbial Electrolysis Cells (MECs) as Innovative Technology for Sustainable Hydrogen Production: Fundamentals and Perspective Applications
1. 11.1 Introduction
2. 11.2 Principles of MEC for Hydrogen Production
3. 11.3 Thermodynamics of MEC
4. 11.4 Factors Influencing the Performance of MECs
5. 11.5 Current Application of MECs
6. 11.6 Conclusions and Prospective Application of MECs
7. Acknowledgments
8. References
Chapter 12: Algae to Hydrogen: Novel Energy-Efficient Co-Production of Hydrogen and Power
1. 12.1 Introduction
2. 12.2 Algae Potential and Characteristics
3. 12.3 Energy-Efficient Energy Harvesting Technologies
4. 12.4 Pretreatment (Drying)
5. 12.5 Conversion of Algae to Hydrogen-Rich Gases
6. 12.6 Conclusions
7. References

Part 3: Photo Hydrogen Production

Chapter 13: Semiconductor-Based Nanomaterials for Photocatalytic Hydrogen Generation
1. 13.1 Introduction
2. 13.2 Semiconductor Oxide-Based Nanomaterials for Photocatalytic Hydrogen Generation
3. 13.3 Semiconductor Sulfide-Based Nanomaterials for Photocatalytic Hydrogen Generation
4. 13.4 Metal-Free Semiconductor Nanomaterials for Photocatalytic Hydrogen Generation
5. 13.5 Summary and Prospects
6. Acknowledgments
7. References
Chapter 14: Photocatalytic Hydrogen Generation Enabled by Nanostructured TiO2 Materials
1. 14.1 Introduction
2. 14.2 Photocatalytic H₂ Generation
3. 14.3 Main Experimental Parameters in Photocatalytic H₂ Generation Reaction
4. 14.4 Types of TiO₂ Nanostructures
5. 14.5 Conclusions and Outlook
6. Acknowledgments
7. References
Chapter 15: Polymeric Carbon Nitride-Based Composites for Visible-Light-Driven Photocatalytic Hydrogen Generation
1. 15.1 Introduction
2. 15.2 General Comments on g-C₃N₄ and its Basic Properties
3. 15.3 Synthesis of Bulk g-C₃N₄
4. 15.4 Functionalization of g-C₃N₄
5. 15.5 Photocatalytic Hydrogen Production Using g-C₃N₄
6. 15.6 Conclusions
7. References

Index

End User License Agreement

List of Tables

Chapter 1

Table 1.1 Summery of SRM reaction over various metal-oxide supported catalyst.
Table 1.2 Summary of SRE over noble metal catalysts.
Table 1.3 Summary of SRE over Co-based catalysts.
Table 1.4 Summary of SRE over Ni-based catalysts.
Table 1.5 Summary of SRE over perovskite-based catalysts.
Table 1.6 Promoting of metal supported catalyst using transition metals.
Table 1.7 Summary of bimetallic catalyst systems for SRE process.
Table 1.8 Summary of SRG over Ni-based catalysts.

Chapter 2

Table 2.1 Specific and volumetric energy densities of common fuels and power sources. (Reprinted with permission from [10]; Copyright © 2013 Elsevier)
Table 2.2 Life-cycle costs of hydrogen production for ammonia decomposition and other hydrogen production technologies. (Adapted from [27])
Table 2.3 Best performance and recommended operating conditions for the Ni- and Ru-based microchannel reactors. (Reprinted with permission from [87]; Copyright © 2015 Elsevier)
Table 2.4 Comparison of global performance of microstructured reactors for pure NH3 decomposition. (Reprinted with permission from [87]; Copyright © 2015 Elsevier)
Table 2.5 Summary of governing equations for modeling the free-fluid and porous catalyst computational domains. (Reprinted with permission from [52]; Copyright © 2014 Elsevier)

Chapter 3

Table 3.1 Ceramic layers deposited onto different ceramic and metallic porous supports.
Table 3.2 Permeation data of some conventional supported membranes.
Table 3.3 Set of assumptions used for the simulation of the reactor systems. (Reprinted with permission from [85]; Copyright © 2014 Elsevier)
Table 3.4 Overview of the techno-economical assessment and comparison of the conventional fired tubular reformer with and without carbon capture, MA-CLR and FBMR concepts. (Reprinted with permission from [1]; Copyright © 2016 Elsevier)

Chapter 5

Table 5.1 The turnover frequency (TOF; mol H_2.(mol metal)^–1(min)^–1) and apparent activation energy (E_a; kJ/mol) values of reported catalysts used in hydrogen generation from the hydrolysis of AB. TOF values were given for the hydrolysis of AB at room temperature.
Table 5.2 Lifetime (TTO) of various catalysts in hydrolysis of ammonia borane at room temperature. The surface area, TOF values and the average particle size of the catalysts are also given for comparison.
Table 5.3 Reusability of the reported catalysts used in hydrogen generation from the hydrolysis of AB at room temperature (TOF values indicate the catalytic activity of the catalysts for the first use).
Table 5.4 Recyclability of the reported catalysts used in hydrogen generation from the hydrolysis of AB at room temperature (ammonia borane was added into the reaction solution without separating the catalyst from the reaction mixture).

Chapter 6

Table 6.1 Thermodynamic voltage E(T) and electrolysis efficiency at atmospheric pressure and different operating temperatures.
Table 6.2 Comparison of main water electrolysis technologies [13].
Table 6.3 EI-250 type electrolyzer performances.
Table 6.4 Comparison of alkaline and PEM water electrolysis technologies.

Chapter 7

Table 7.1 Summary of proton exchange membranes discussed in this work.
Table 7.2 Summary of values obtained by the electrical equivalent model for N117 at 80 °C [41].

Chapter 8

Table 8.1 Structural compounds and chemical composition of biomass and bio–oils produced.
Table 8.2 Summary of different bio–oil reforming processes.

Chapter 9

Table 9.1 Reaction conditions and results for the two-stage gasification of different feedstocks.
Table 9.2 Effects of type and amount of activated carbon on producer gas composition.
Table 9.3 Effect of temperature on producer gas composition in two-stage gasification.
Table 9.4 Effect of gasifying agent on producer gas composition.
Table 9.5 Comparison of two-stage and three-stage gasifiers.
Table 9.6 NH₃ and H₂S contents in the producer gases from three-stage gasification.

Chapter 10

Table 10.1 Summary of the values obtained for the tuning of the selected controller applied in the biologic-only hydrogen production system using heuristic criteria from Section 10.5.
Table 10.2 Summary of the values obtained for the tuning of the selected controller applied to the biologic-photochemical hydrogen production system using heuristic criteria from Section 10.5.
Table 10.3 Comparison of the biohydrogen productivities by Desulfovibrio bacteria reported in the literature versus the ones obtained by applying enhancement techniques.

Chapter 11

Table 11.1 Electrochemically active bacteria (EAB) used in MECs.
Table 11.2 Summary of reported anode electrode materials used in MECs.
Table 11.3 Summary of cathodic electrode materials and catalysts used in MECs. Included are key performance parameters of MEC tests; hydrogen production rate (HPR), cathodic hydrogen recovery (RCAT), overall energy efficiency or recovery (h_E_+S).
Table 11.4 Summary of membranes/separators reported in previous MEC studies.
Table 11.5 Summary of the value-added products from MECs platform.

Chapter 12

Table 12.1 The compositions of some representative macro- and microalgae species.
Table 12.2 Assumed SCWG conditions and syngas composition for system evaluation.
Table 12.3 Hydrogen separation and hydrogenation conditions.
Table 12.4 Conditions of conventional thermal gasification and compositions of produced syngas [55].

Chapter 13

Table 13.1 Rate of hydrogen generation obtained by using different morphologies of TiO₂ materials.
Table 13.2 Multi-metal sulfide nanomaterials for photo catalytic hydrogen production.
Table 13.3 Photocatalytic properties of g-C₃N₄-based complex system.

Chapter 14

Table 14.1 Some composite TiO₂ photocatalysts for photocatalytic hydrogen generation.

Chapter 15

Table 15.1 Summary of the experimental conditions, hydrogen evolution rates, apparent quantum efficiencies and enhancement factors for different g-C₃N₄-based composites published in 2016 (indexed in WOS; bibliographical survey updated on August 31).

List of Illustrations

Chapter 1

Figure 1.1 Effects of La₂O₃ on the performance of Co/CeO₂ in SRE. (Adapted from [142])
Figure 1.2 Coke formation at different stages of SRE over Ni/Al₂O₃-La₂O₃. (Adapted from [167])
Figure 1.3 Inhibition of coke formation in Ni-Pt bimetallic catalyst. (Adapted from [226])
Figure 1.4 Comparison between different oxide supports for SRG over Ni. (Adapted from [263])
Figure 1.5 Bimetallic Ni-Sn supported on CeO₂-MgO-Al₂O₃. (Adapted from [283])
Figure 1.6 Role of electric discharge in enhancing the SRM catalytic activity. (Adapted from [45])
Figure 1.7 Postulated reaction mechanism in the presence of electric discharge. (Adapted from [45])
Figure 1.8 A set of possible reaction pathways in SRE. (Adapted from [320])
Figure 1.9 The proposed reaction mechanism by Wu et al. [320].
Figure 1.10 Reaction pathways for the different types of coking over Ni/SiO₂. (Adapted from [174])
Figure 1.11 Simplified reaction mechanism over Ni-Pt/CeO₂. (Adapted from [227])
Figure 1.12 Reaction moved from liquid to gaseous product by adding MgO. (Adapted from [282])
Figure 1.13 The proposed SRG reaction mechanism over Ni/monolithic catalyst. (Adapted from [333])

Chapter 2

Figure 2.1 Concept overview of ammonia-to-hydrogen for distributed fuel cell power applications.
Figure 2.2 Five-year ammonia price trends in various global markets. (Adapted from Market Realist [22])
Figure 2.3 Ammonia conversion and system volume targets for an ammonia cracker capable of producing 5 kg of H₂ based on the DOE FreedomCAR. High catalytic activity compact devices are desirable to meet these targets. (Adapted from [55])
Figure 2.4 Depictions of the reactor with laser-welded inlet/outlet tubes, heating block and electric heater cartridges. (Reprinted with permission from [83]: Copyright © 2014 Elsevier)
Figure 2.5 Three-dimensional CAD depictions of (a) microstructured platelet showing 80 channels and inlet and outlet fluid distribution manifolds; (b) platelet with only manifolds engraved and for laser welding on microstructured platelet to complete the microchannel reactor; (c) zoomed view of first 5 channels from the far-side wall of the metal substrate; (d) cutaway schematic of an uncoated channel showing channel dimensions. (Reprinted with permission from [83]; Copyright © 2014 Elsevier)
Figure 2.6 Effect of reaction temperature and space velocity on NH₃ conversion for (a) Ni-catalyzed and (b) Ru-catalyzed ammonia decomposition. (Reprinted with permission from [83, 87]; Copyright © 2014, 2015 Elsevier)
Figure 2.7 Comparison of CFD simulation results with experimental data: (a) NH₃ conversion as a function of reactor temperature for the Ni-based microchannel reactor; (b) NH₃ conversion as a function of NH₃ flow rates at different reaction temperatures for the Ru-based microchannel reactor. (Reprinted with permission from [52, 53]; Copyright © 2014, 2016 Elsevier)
Figure 2.8 (a) Axial velocity distribution within channels for the Ni-based microreactor as a function of normalized channel height (z/H) at axial location x = 2.5 cm; (b) Zoomed view of the axial velocity profile within the porous washcoat in the transverse direction at axial location x = 2.5 cm. (Reprinted with permission from [52]; Copyright © 2014 Elsevier)
Figure 2.9 Contours of temperature in the mid x-z plane along the microchannel length for (a) Ni-based microchannel reactor. Reaction conditions: T = 973 K, NH₃ flow rate = 50 Nml min^-1; (b) Ru-based microchannel reactor. Reaction conditions: T = 723 K, NH₃ flow rate = 500 Nml min^-1. (Reprinted with permission from [52, 53]; Copyright © 2014, 2016 Elsevier)
Figure 2.10 NH₃ concentration distribution in the transverse direction (normalized channel height, z/H) at axial locations from the microchannel inlet for (a) Ni-based microreactor. Reaction conditions; 973 K and 50 Nml min^-1 NH₃ flow. x = 10, 30, 50, and 60 μm; (b) Ru-based microreactor. Reaction conditions; 873 K and 500 Nml min^-1 NH₃ flow. x = 10, 200, 500, and 1000 μm. (Reprinted with permission from [52, 53]; Copyright © 2014, 2016 Elsevier)

Chapter 3

Figure 3.1 (a) H₂ and N₂ permeance of the ceramic supported thin Pd-Ag membrane (~4 µm thick) at 600 °C during long-term single gas tests performed over 7 days and SEM images of the surface at (b) 175 × and (c) 750 × magnifications. (Reprinted with permission from [57]; Copyright © 2015 Elsevier)
Figure 3.2 H₂ permeance (open circles) and H₂/N₂ ideal permselectivity (closed circles) of two metallic supported thin Pd-Ag membranes as a function of time on stream at 500–600 °C and 400 °C. (Reprinted from [40] and [61] with permission from Elsevier and Eindhoven University of Technology Repository)
Figure 3.3 SEM images of the membrane: (a) and (b) are cross-section images showing Pd-Ag layers with defects; (c) shows the surface of the membrane, while (d) is a more detailed image of the membrane surface where the black surrounding the particle seems to be a hole presenting several defects. The figure is accompanied by EDX measurements of the positions pointed out in image (d). (Reprinted with permission from [40]; Copyright © 2016 Elsevier).
Figure 3.4 Summary of the steam methane reforming (SMR) in a FBMR with five tubular Pd-Ag/ZrO₂ membranes prepared at TECNALIA. Left: table overview of the results obtained with these membranes and right: retentate composition at 550 and 600 °C. (Reprinted with permission from [57]; Copyright © 2015 Elsevier)
Figure 3.5 Methane conversion as a function of temperature and pressure for the two reactor configurations studied (fluidized bed reactor (FBR) and fluidized bed membrane reactor (FBMR)) using metallic supported Pd-Ag membrane, for steam methane reforming (top figures) and autothermal reforming (bottom figures) with reference case conditions and the thermodynamic equilibrium for each reaction calculated with Aspen Plus v7.3.2. (Reprinted with permission from [40]; Copyright © 2016 Elsevier)
Figure 3.6 Drawing of different technologies for H₂ production integrating CO₂ capture: (a) Fluidized Bed Membrane Reactor (FBMR), (b) Membrane-Assisted Chemical Looping Reforming (MA-CLR) and (c) Chemical Looping Reforming (CLR). (Reprinted with permission from [85]; Copyright © 2014 Elsevier)
Figure 3.7 Simplified scheme of the simulated plants. (Reprinted with permission from [85]; Copyright © 2014 Elsevier)
Figure 3.8 Left: Reforming efficiency with the three different concepts investigated as a function of the reforming temperature; right: CO₂ purity of the main flue stream line. (Reprinted with permission from [85]; Copyright © 2014 Elsevier).
Figure 3.9 Schematic description of the benchmark fired tubular reforming plant for H₂ production with integrated carbon capture system. (Reprinted with permission from [1]; Copyright © 2016 Elsevier)

Chapter 4

Figure 4.1 Schematic diagram of photocatalytic ethanol reforming.
Figure 4.2 Product distribution from ethanol steam reforming at thermodynamic equilibrium with EtOH:Water = 1:10 (molar), C_EtOH = 2.8%, and atmospheric pressure.
Figure 4.3 Effect of EtOH-to-water molar ratio on equilibrium H₂ yield and C selectivity at (no dilution).
Figure 4.4 Effect of dilution on equilibrium hydrogen yield (Dilution ratio used: Inert:EtOH:H₂O = 25:1:10).
Figure 4.5 Effect of pressure on equilibrium hydrogen yield (EtOH:Water = 1:10 (molar ratio), no dilution).
Figure 4.6 Proposed reaction mechanism for ethanol steam reforming over supported Co catalysts.

Chapter 5

Figure 5.1 Illustration of electrostatic stabilization (a) and steric stabilization (b).
Figure 5.2 Schematic illustration of characterization techniques for catalysts.

Chapter 6

Figure 6.1 Temperature dependence of main thermodynamic parameters for water electrolysis.
Figure 6.2 Polarization curves (U-i) and specific energy consumption of main water electrolysis technologies: (1) Industrial alkaline electrolyzers (70–95 °C); (2) PEM electrolyzers (90–110 °C; 0–3.0 MPa); (3) High-temperature solid-oxide electrolyzers (900 °C) with additional heat supply.
Figure 6.3 Schematic diagram of the alkaline electrolysis cell.
Figure 6.4 Electrochemical performances of a conventional alkaline water electrolysis cell [13]. I: thermodynamic voltage; II: ohmic drop in the electrolyte; III: anodic overvoltage associated with the OER; IV: cathodic overvoltage associated with the HER; V: ohmic drop in the main power line. ε_ΔH = enthalpy efficiency.
Figure 6.5 Alkaline water electrolysis modules (filter-press design) developed by Nel Hydrogen. (Image courtesy of Nel Hydrogen [31]).
Figure 6.6 HySTAT^® containerized hydrogen generator produced by Hydrogenics. (Image courtesy of Hydrogenics [32]).
Figure 6.7 The Heliocentris HG100 hydrogen generator based on an innovative alkaline solid polymeric membrane technology produced by Heliocentris [33].
Figure 6.8 Schematic diagram of a cell in the chlorine-alkali process according to [44].
Figure 6.9 The structural formula of Nafion membrane by E. I. du Pont de Nemours and Company.
Figure 6.10 Schematic diagram of PEM electrolysis cell.
Figure 6.11 Current-voltage relationship measured using 7 cm² single electrolysis cell at 90 °C and atmospheric pressure of gases; cathodic catalyst (HER): Pt40/Vulcan XC-72 (0.7 mg/cm² of metal); anodic catalyst (OER): black Ir (2.4 mg/cm²); Nafion-115 membrane. P = 1 bar [54].
Figure 6.12 The world’s largest electrolysis system by Siemens transforms wind power into hydrogen [64].
Figure 6.13 Hydrogen C-Serie generator produced by Proton OnSite. (Image courtesy of Proton OnSite [67]).
Figure 6.14 The AREVA H2Gen PEM electrolyzer [68].
Figure 6.15 ITM Power’s HPac mid-range hydrogen generator (left) and HFuel self-contained module (right) suitable for refueling hydrogen-powered vehicles and forklift trucks. (Images courtesy of ITM Power [70]).
Figure 6.16 The HG 2200R model hydrogen gas generator developed by Claind [71].
Figure 6.17 PEM electrolysis stacks (productivity 2.5 m³/h) and electrolysis plant (operating pressure 130 bar) developed by NRC “Kurchatov Institute” together with Federal State Unitary Enterprise “Red Star.”
Figure 6.18 A MEA sample offered by Greenerity GmbH [77].
Figure 6.19 A schematic diagram of a solid-oxide electrolysis cell.
Figure 6.20 Electrolysis cells of tubular design. (a) NiO/YSZ tubes produced by extrusion. (b) Cross section of a tube [95].
Figure 6.21 Photographs of bipolar plate, MEA and stack used in planar solid oxide electrolyzers technology. (Images courtesy of Ceramatec [96]).

Chapter 7

Figure 7.1 Acid stability results for PBI-based membranes as a function of sulfuric acid concentration testing [28].
Figure 7.2 Additional PBI-based acid stability data including Nafion 212 (PFSA-based) [29].
Figure 7.3 IEC values of PBI-based membranes before and after acid treatment at 80 °C for 120 h [28].
Figure 7.4 Typical TGA (a) data obtained for acid treated polymers and (b) the converted data to determine the temperature range where mass loss occurs [23].
Figure 7.5 (a) Typical impedance data obtained for SO₂ electrolysis at 0.25A cm ², N117 and 80 °C and (b) the electrical equivalent circuit used for the model.
Figure 7.6 Impedance data obtained as a function of hot pressing pressure for a N117 at 80 °C for 0.25A cm^-2 [50].
Figure 7.7 Polarization curves showing the effect of hot pressing pressure on SO₂ electrolysis performance for N117 [27].
Figure 7.8 Data obtained for an accelerated stress test (voltage stepping) done for stability tests on base-excess PBI blend membranes [24].
Figure 7.9 Long-term voltage stability at 0.1 A cm^–2 for PBI-based membranes compared to the baseline N115.
Figure 7.10 Effect of H₂S concentration on the performance of the SO₂ electrolyzer [62].
Figure 7.11 Cyclic voltammogram used during CO stripping to determine the ECSA as a function of contamination concentration.
Figure 7.12 Voltage stability for the SO₂ electrolyzer with H₂S as impurity [46].
Figure 7.13 MEA stability of novel PBI-based membranes for use in high temperature SO₂ electrolysis.

Chapter 8

Figure 8.1 Alternatives to produce hydrogen from of biomass.
Figure 8.2 Main biomass components and their main building blocks.
Figure 8.3 Possible cellulose pyrolysis mechanism with final product examples.
Figure 8.4 Schemes of different pyrolysis reactors: (a) bubbling fluid bed with a char combustor (dotted line) for a transported fluid bed, (b) rotating cone reactor, (c) auger reactor, (d) drop tube reactor, (e) vacuum reactor, (f) ablative reactor.
Figure 8.5 Different reforming reactor configurations: Fixed bed reactor (left), fluidized bed reactor (middle) and membrane reactor (right).
Figure 8.6 Chemical looping steam reforming reactor setup.
Figure 8.7 Sorption enhanced chemical looping reforming reactor setup.

Chapter 9

Figure 9.1 Diagram of the two-stage UOS gasification process.
Figure 9.2 Diagram of the three-stage UOS gasification process.
Figure 9.3 Producer gas composition from DSS gasification at various ERs (• H₂, ○ CH4, ▼ CO, Δ CO₂, ♦ tar).
Figure 9.4 Tar removal mechanisms over activated carbon: (a) tar adsorption and coke formation and (b) thermal and catalytic tar (or coke) cracking and tar (or coke) cracking via reactions with gas components.
Figure 9.5 H₂ and tar development in producer gas with respect to gasification time.
Figure 9.6 Pore size distributions of fresh and spent activated carbons.

Chapter 10

Figure 10.1 Diagram of the proposed operational regime for hydrogen production by SRB via a hybrid biologic plus electrochemical process.
Figure 10.2 Validation of the chosen kinetic model for hydrogen production by SRB under batch fermentation versus experimental data reported by López-Pérez et al. [25].
Figure 10.3 Validation of the chosen kinetic model for hydrogen production by SRB under batch regime of a hybrid biologic and photochemical system versus experimental data reported by López-Pérez et al. [25].
Figure 10.4 Dynamic analysis of the chosen kinetic model for hydrogen production by SRB under continuous fermentation by bifurcation analysis considering the dilution rate (D) as bifurcation parameter.
Figure 10.5 Dynamic analysis of the chosen kinetic model for hydrogen production by SRB under continuous fermentation by bifurcation analysis considering the feeding sulphate concentration (SO_in) as bifurcation parameter.
Figure 10.6 Dynamic analysis of the chosen kinetic model for hydrogen production by SRB under continuous fermentation by bifurcation analysis considering the feeding lactate concentration (Lacin) as bifurcation parameter.
Figure 10.7 Dynamic analysis of the chosen kinetic model for hydrogen production by SRB under continuous regime at the biological-photochemical process obtained by bifurcation analysis considering the dilution rate (D) as bifurcation parameter.
Figure 10.8 Dynamic analysis of the chosen kinetic model for hydrogen production by SRB under continuous regime at the biological-photochemical process obtained by bifurcation analysis considering the feeding cadmium concentration (CdL_in) as bifurcation parameter.
Figure 10.9 Comparison of the dynamics of biohydrogen productivity of the SRB fermentation system under both open-loop (continuous line) and closed-loop (discontinuous line) operation.
Figure 10.10 Comparison of the dynamics of biohydrogen productivity of the SRB photochemical fermentation system under both open-loop (continuous line) and closed-loop (discontinuous line) operation.

Chapter 11

Figure 11.1 Schematic representation of a typical two-chamber MEC reactor and its operation.
Figure 11.2 Schematic diagram describing the EET mechanisms in an MEC anode: (A) Direct electron transfer: cell in direct contact with electron acceptor via surface c-type cytochromes, (B) Electron transfer through electron shuttle, (C) Electron transfer through conductive biofilm and conductive pili.

Chapter 12

Figure 12.1 Technologies for energy harvesting from algae. (Reprinted from [41] with permission from Elsevier).
Figure 12.2 Basic idea of exergy recovery technology: (a) stream’s exergy elevation and heat pairing between the exergy-elevated stream (hot stream) and cold stream, (b) two examples of exergy elevation. (Reprinted from [23] with permission from Elsevier).
Figure 12.3 Schematic process flow diagram of algae drying. (Reprinted from [41] with permission from Elsevier)
Figure 12.4 Calculated total required work (compressor and blower) in relation to target moisture content during drying (Chlorella sp., wet algal flow rate 1 t h^–1). (Reprinted from [41] with permission from Elsevier)
Figure 12.5 Conceptual diagram of hydrogen and power co-production from algae employing SCWG. (Reprinted from [23] with permission from Elsevier)
Figure 12.6 Proposed integrated-system of hydrogen and power production from algae. (Reprinted from [23] with permission from Elsevier)
Figure 12.7 Calculated total energy efficiency in relation to fluidization velocity under different gasification pressure. (Reprinted from [23] with permission from Elsevier)
Figure 12.8 Temperature-enthalpy diagram of integrated system (gasification pressure and fluidization velocity are 25 MPa and 1 U_mf, respectively). (Reprinted from [23] with permission from Elsevier)
Figure 12.9 Schematic diagram of basic hydrogen and power co-production from algae employing conventional thermal gasification.
Figure 12.10 Process flow diagram of power generation from algae with conventional thermal gasification. (Reprinted from [15] with permission from Elsevier).
Figure 12.11 Total net power and energy efficiency of integrated system for power generation from algae with conventional thermal gasification including drying. (Reprinted from [15] with permission from Elsevier).

Chapter 13

Figure 13.1 Basic principle of water splitting on TiO₂ photocatalyst.
Figure 13.2 The SEM (a) and TEM images (b-d) of the S-doped porous anatase TiO₂ nanopillars. (Reprinted with permission from [20]).
Figure 13.3 2D (a) and 3D (c) atomic force microscope images and the thickness (b) of the stable mesoporous black TiO₂ nanosheets. (Reprinted with permission from [24]).
Figure 13.4 The SEM and TEM images of stable mesoporous black TiO₂ hollow spheres. (Reprinted with permission from [28]).
Figure 13.5 Photocatalytic hydrogen evolution of the mesoporous black TiO₂ hollow spheres (a) and mesoporous TiO₂ hollow spheres (b). (Reprinted with permission from [28]).
Figure 13.6 Representative TEM images along (a) [100] plane and (b) [110] plane; (c,d) HRTEM images of the ordered mesoporous black TiO₂ materials after hydrogen gas annealing at 500 °C (c,d). (Reprinted with permission from [33])
Figure 13.7 Mechanism of ZnO photocatalytic water splitting for hydrogen production.
Figure 13.8 Schematic representation of the hydrogen production mechanism in the Zn_xBi₂S_3+x/WO₃ photocatalysts.
Figure 13.9 Proposed mechanism for γ’-Fe₄N/α-Fe₂O₃ nanocatalysts in photocatalytic hydrogen evolution.
Figure 13.10 Schematic mechanism for the H₂ evolution activity of CdS coupling with other semiconductor with wide band gap.
Figure 13.11 Preparation of MBT/MoS₂/MBT sandwich-like nanosheets. (Reprinted with permission from [101])
Figure 13.12 The SEM and HRTEM images of MBT/MoS₂/MBT. (Reprinted with permission from [101])
Figure 13.13 Schematic representation of the hydrogen production mechanism in the TiO₂/g-C₃N₄ photocatalysts.
Figure 13.14 Schematic representation of the hydrogen production mechanism in the CdLa₂S₄/g-C₃N₄ photocatalysts.
Figure 13.15 Proposed mechanism for graphene-based photocatalysts in photocatalytic hydrogen generation.
Figure 13.16 Proposed mechanism for triazine-based photocatalysts in photocatalytic hydrogen generation.

Chapter 14

Figure 14.1 Number of articles published on H₂ production from 2000 to 2015.
Figure 14.2 Schematic illustration of three basic processes of photogenerated electrons and holes during photocatalytic water splitting.
Figure 14.3 Schematic illustration of photocatalytic H₂ evolution under the proposed hole shuttle mechanism. The blue arrows represent the movement of the various species and the red ones represent redox reactions. (Reproduced with permission from [10]. Copyright © 2014 Nature Publishing Group).
Figure 14.4 (a) Schematic illustration of the structure and electronic density of states (DOS) of black TiO₂. Dopants are displayed as black dots, and disorder is depicted in the outer layer of the nanocrystal. E_c and E_v refer to CB and VB, respectively. The energy bands of white and black TiO₂ are shown at the left and right, respectively. (b) Photos of white and black TiO₂. High-resolution transmission electron microscopy images of (c) white and (d) black TiO₂. In (d), a short dashed curve outlines a portion of the interface between the crystalline inner part and the disordered outer part. (Reproduced with permission from [31]; Copyright © 2011 AAAS).
Figure 14.5 (a) Schematic illustration of the new VB formation by doping of non-metal ions. (b) Calculated imaginary parts of the dielectric functions (ε₂), which are averaged over three (x, y and z) polarization vectors. (c) Total DOS of doped TiO₂ and (d) the projected DOS of the doped anion sites, calculated by FLAPW. The dopants F, N, C, S and P were located at a substitutional site for an O atom in the anatase TiO₂ crystal (the eight TiO₂ units per cell). The results of N doping at interstitial sites (N-doped) as well as at both substitutional and interstitial sites (N_i+s-doped) are also presented. ((a) Reproduced with permission from [43]; Copyright © 2010 American Chemical Society; (b-d) Reproduced with permission from [44]; Copyright © 2001 AAAS).
Figure 14.6 Schematic illustration of the formation of a new donor level (a) and a new acceptor level (b) by metal ion doping. (c) The relationship between the metal-ionic radius and the band gap change of TiO₂. ((a,b) Reproduced with permission from [43]; Copyright © 2010 American Chemical Society; (c) Reproduced with permission from [61]; Copyright © 1999 The Chemical Society of Japan).
Figure 14.7 SEM images of Pd quantum dot-decorated TiO₂ nanotube arrays: (a) top view and (b) cross-sectional view. (c) IPCE measured at 0.9 V_SCE in 0.5 M KOH. (d) Amount of H₂ produced by utilizing different photoanode and cathode electrodes at –0.3 V_SCE in a photoelectrochemical cell containing a 2 M Na₂CO₃ and 0.5 M ethylene glycol solution under 320 mW cm^–2 irradiation. PE and CE refer to photoanode electrode and cathode electrode, respectively. (Reproduced with permission from [67]; Copyright © 2012 American Chemical Society).
Figure 14.8 (a,d,g) TEM images, (b,e,h) photocatalytic H₂ evolution, and (c,f,i) schematic illustrations of the CdS/MoS₂/TiO₂, 5 wt% RuO₂/TiO₂, and Au@TiO₂–0.2CdS composites. ((a–c) Reproduced with permission from [86]; Copyright © 2015 Royal Society of Chemistry; (d–f) Reproduced with permission from [79]; Copyright © 2015 American Chemical Society; (g–i) Reproduced with permission from [88]; Copyright © 2013 American Chemical Society).
Figure 14.9 Schematic of the mechanism of graphene/TiO₂ nanocomposites for photocatalytic H₂ generation under UV light illumination. (Reproduced with permission from [112]; Copyright © 2011 Royal Society of Chemistry.

Chapter 15

Figure 15.1 Reaction pathway for the development of g-C₃N₄ using cyanamide as the precursor. (Adapted from [3])
Figure 15.2 Multiple functionalities of g-C₃N₄. (Adapted from [13])
Figure 15.3 Schematic illustration of band positions in g-C₃N₄ (at pH = 7) relative to the normal hydrogen electrode (NHE). η_ox/η_red: overpotential for water oxidation/H⁺ reduction (adapted from [14]). It should be noted that, although the band edges of the semiconductor photocatalyst usually exhibit a pH dependence (E_CB = E²_CB (pH = 0) –0.059 pH)), the redox potentials of water also have the same linear pH dependence with a slope of 0.059 V/pH, and thus there is no change in the overpotential of photogenerated charges for water redox at different pH values.
Figure 15.4 Some of the most popular N-rich precursors used in the synthesis of g-C₃N₄.
Figure 15.5 Schematic representation of a layer fragment of melamine cyanurate adduct.
Figure 15.6 Schematic illustration of the band structures of typical samples of g-C₃N₄ in comparison to TiO₂: g-C₃N₄, S-g-C₃N₄, B-g-C₃N₄, O-g-C₃N₄ and C-g-C₃N₄ NHE stands for normal hydrogen electrode. (Adapted from [4])
Figure 15.7 A schematic diagram of g-C₃N₄ framework with metal ion (Mⁿ⁺) inclusion.
Figure 15.8 Schematic energy diagram of a type II heterojunction.
Figure 15.9 Schematic fundamental mechanisms of photocatalytic overall water splitting with Z-scheme system: (a) S-S system and (b) S-EM-S system. (Adapted from [11])

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Advances in Hydrogen Production and Storage

Series Editors: Mehmet Sankir and Nurdan Demirci Sankir

Scope: Energy is one of the most important issues for humankind. Increasing energy demand, regional limitations, and serious environmental effects of the conventional energy sources provide the urgent need for new, clean, and sustainable energy. Advances in Hydrogen Production and Storage emphasizes the basics of renewable energy and storage as well as the cutting edge technologies employed for these applications. The series focuses mainly on hydrogen generation, photoelectrochemical solar cells, fuel cells and flow batteries.

Submission to the series:
Please send book proposals to Mehmet Sankir at
mehmetsankir@yahoo.com

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Preface

Energy is one of the most important issues for humankind. Increasing energy demand, regional limitations and serious environmental effects of conventional energy sources have brought about the need for new, clean and sustainable energy. This book series has been planned as a presentation of the basics in the areas of renewable energy and storage as well as the cutting-edge new technologies for these applications. Hydrogen Production Technologies is the first volume of the series due to the undeniable importance of hydrogen as a clean energy carrier. Hydrogen has been gaining more attention in both transportation and stationary power applications. Fuel cell-powered cars are on the roads and the automotive industry is demanding feasible and efficient technologies to produce hydrogen. There are various ways to produce hydrogen in a safe and cost-effective manner. This volume covers the new technologies used to obtain hydrogen more efficiently via catalytic, electrochemical, bio- and photohydrogen production and as such is a valuable component in the research area of hydrogen production. The principles and methods described herein lead to reasonable mitigation of the great majority of problems associated with hydrogen production technologies. The book is edited to be useful as a text for university students at both introductory and advanced graduate levels and as a reference text for researchers in universities and industry. The chapters are written by distinguished authors who have extensive experience in their fields. Besides researchers in the engineering area, those in the energy, materials science and chemical engineering fields have been focusing on new materials and production technologies in order to generate hydrogen in an efficient and cost-effective way. Hence a multidisciplinary approach is taken to covering the topics of this book. Readers will absolutely have a chance to compare the fundamental production techniques and learn about the pros and cons of these technologies.

The book is organized into three parts. Part I shows the catalytic and electrochemical principles involved in hydrogen production technologies. It should be clear from this part that the fundamentals and modern status of water electrolysis, ammonia decomposition, methane reforming, steam reforming of hydrocarbons and biethanol, hydrolysis of ammonia borane and also SO₂ electrolyzer are of great importance. Therefore, their various aspects are discussed such as catalyst development, thermodynamics and kinetics of reaction mechanisms, reactor and mathematical modeling, novel membrane structures, and advanced nanoparticles. Part II is devoted to biohydrogen production. This part is designed to be a good introduction to gasification and fast pyrolysis of biomass, dark fermentation, microbial electrolysis and power production from algae. It specifically presents various catalytic formulations as well as reactor designs to overcome catalytic deactivation due to coking. In addition to gasification of wood, dried sewage sludge, and plastic waste, newly developed staged gasifiers with fewer impurities are discussed. Moreover, there is a discussion of dark fermentation using sulphate-reducing bacteria from the genus Desulfovibrio utilized in hydrogen production. Part II also addresses hydrogen production from electrochemically active bacteria (EAB) by decomposing organic compound into hydrogen in microbial electrolysis cells (MECs). Lastly, highly efficient harvesting of energy from algae in the forms of hydrogen and enhanced process integration reducing exergy destruction are demonstrated. The last part of the book is concerned with photohydrogen generation. Recent developments in the area of semiconductor-based nanomaterials, specifically semiconductor oxides, nitrides and metal-free semiconductor-based nanomaterials for photocatalytic hydrogen production are extensively discussed. Moreover, Part III also includes pristine and doped TiO₂ nanostructures for fast hydrogen production during photocatalytic water splitting. Finally, an earth abundant catalyst for water splitting is presented as a very promising narrow band gap visible-light photocatalyst.

Since the findings range over many useful topics specifically discussed in the book, readers from diverse fields such as chemistry, physics, materials science and engineering, mechanical and chemical engineering and also energy-focused engineering programs can benefit from this comprehensive review of the hydrogen production technologies.

Series Editors
Mehmet Sankır, PhD and Nurdan Demirci Sankır, PhD
Department of Materials Science and Nanotechnology Engineering
TOBB University of Economics and Technology
Ankara, Turkey
January 1, 2017