This thesis has studied CO2 reforming of CH4 in atmospheric pressure, non-thermal plasma discharges. The objective of this research was to improve the current understanding of plasma-catalytic interactions for methane reforming. Chapter 1 introduces the existing and potential applications for methane reforming products. The industrial approaches to methane reforming and considerations for catalyst selection are discussed. Chapter 2 introduces non-thermal plasma technology and plasma-catalysis. An introduction to the analytical techniques used throughout this thesis is given. Chapter 3 investigates the effects of packing materials into the discharge gap. The materials were found to influence the reactant conversions for dry reforming of methane in the following order: quartz wool > no packing > Al2O3 > zeolite 3A > BaTiO3 > TiO2. In addition to the dielectric properties, the morphology and porosity of the materials was found to influence the reaction chemistry. The materials also affected the electrical properties of the plasma resulting in surface discharges, as opposed to a filamentary discharge mode. Chapter 4 investigates the effects of variation in CH4/CO2 ratios on plasma-assisted dry reforming of CH4. Differences in the reaction performance for different feed gas compositions are explained in terms of the possible reaction pathways and the electron energy distribution functions. A NiO/Al2O3 catalyst is introduced for plasma-catalytic dry reforming of CH4, which was found to have no significant effect on the reaction performance at low specific input energies. Chapter 5 presents the plasma-assisted reduction of a NiO/Al2O3 catalyst by CH4 and H2/Ar discharges. When reduced in a CH4 discharge, the active Ni/Al2O3 catalyst was effective for plasma-catalytic methane decomposition to produce H2 and solid carbon filaments. A decrease in the breakdown voltage was observed, following the catalyst reduction to the more conductive Ni phase. Chapter 6 investigates the performance of the plasma-reduced Ni/Al2O3 catalysts for plasma-catalytic dry reforming of methane. Whilst the activity towards dry reforming of CH4 was low, the CH4 plasma-reduced catalyst was found to be effective for catalysing the decomposition of CH4 into H2 and solid carbon filaments; both potentially useful products. Chapter 7 discusses further work relevant to this thesis.

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The search for an alternative clean and renewable energy source has become an urgent matter. One such energy-saving technology is a fuel cell; it uses fuel as the source of energy to produce electricity directly and the byproducts formed are not as voluminous and environmentally harmful. The conventional low temperature fuel cells use hydrogen as the fuel which is produced from conventional fuels via reforming. However, developing reformers for hydrocarbon fuels requires AN understanding of the fundamental mechanisms and kinetics studies. In this study, simple hydrocarbon fuel, namely methane, in external reforming or internal reforming within a solid oxide fuel cell has been studied because of its importance and with the hope that it will ultimately lead to an understanding of reforming of higher hydrocarbons, such as logistic fuels like JP-8. For this purpose, methane was used the starting point and building block for the progressive understanding of reforming of complex hydrocarbons. Methane steam reforming (MSR), CH4 + 2H2O = CO2 + 4H2 is, in fact, the most common method of producing commercial bulk hydrogen along with the hydrogen used in ammonia plants. United States alone produces 9 million tons of hydrogen per year. The overall MSR reaction CH4 + 2H2O = CO2 + 4H2 is in fact composed of two reactions, the water gas shift reaction, CO + H2O = CO2 + H2, which has recently been investigated by a former Ph.D. student in our group, Caitlin Callaghan. Here, the first reaction CH4 + H2O = CO + 3H2, i.e., methane reforming, is analyzed using a reaction route network approach to obtain the overall methane steam reforming network and kinetics. Kinetics providing detailed information of elementary reaction steps for this system, namely micro-kinetics, has not yet been fully addressed. Employing the theory of Reaction Route Network Theory, recently developed by Fishtik and Datta, and using the Unity Bond Index-Quadratic Exponential Potential (UBI-QEP) method of Shustorovich to predict elementary step kinetics coupled with transition-state theory, a detailed microkinetic model of steam and dry reforming of methane has been developed for Rh(111) and Ni(111) in this thesis. While there is extensive literature on it, the standard reference on the mechanism and kinetics of MSR is that of Xu and Froment, who proposed a 13 step mechanism. Based on the assumption of rate limiting steps for these overall reactions, Xu and Froment derived rate expressions for overall kinetics with fitted parameters. Here a more detailed micro-kinetic model of steam reforming of methane has been developed by adding 3 steps pertinent to carbon formation on the catalyst to Xu and Froment's mechanism. The complete set as well as the dominant reaction routes has been identified. This was accomplished first by enumerating the list of reaction routes and drawing this network. A program was written in Maple and was used to assist in creating the list of full routes, empty routes and intermediate nodes. This program reduces the amount of repetitive work that was needed in an earlier Matlab program when computing the list. After drawing the complete reaction network it was than converted into an equivalent electrical circuit and Multisim analysis was performed. Further, the resistances of various reaction steps were compared. From the reduced graph, it was determined that reaction steps pertaining to desorption of carbon dioxide, i.e., step s4, and intermediate methylene forming intermediate methylidyne, s11, are the rate limiting steps. Further, through simulation with Multisim, it was determined that in fact only 2 overall reactions are needed. Adding a third overall reaction results in a nodal balance error. A rate expression was developed based on assuming the above two rate determining steps, with remaining steps at pseudo equilibrium along with the quasi-steady state approximation. The rate expression however produced a substantial error in conversion when compared to the overall microkinetic model. In addition to computing the micro-kinetic model, experimental work for methane steam reforming was conducted. A steam to carbon ratio of 2:1 was fed to the packed bed reactor, where experimental conversion data were obtained. These data points for Ni and Rh catalyst were plotted against the model to see how well the simulation predicted the experimental results. Reasonable agreement was obtained.

Thesis (Ph. D.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains xii, 162 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 139-150).

With the increase in production of biodiesel, a glut of glycerol has resulted in the world market. Glycerol, once a valuable chemical, has become a recalcitrant byproduct. It is also a potential renewable feedstock for hydrogen production. This study is focused on hydrogen production from glycerol steam reforming. During the initial stage, effect of process variables, such as system pressure (1-5 atm), temperature (327 – 727 oC), and water/glycerol molar ratio of (1:1-9:1) on hydrogen yield was investigated using a thermodynamic analysis. The equilibrium concentrations of different compounds were calculated by the method of Gibbs free energy minimization. The study revealed that the best conditions for producing hydrogen is at temperature > 627 oC, atmospheric pressure, and water/glycerol molar ratio (WGMR) 9:1. As a part of catalysts screening, 14 catalysts were prepared on monoliths and tested for their activity. Effects of those catalysts on hydrogen selectivity and glycerol conversion in temperatures ranging from 600-900 oC were discussed. Ni/Al2O3 and Rh/CeO2/Al2O3 were found to be the best performing catalysts based on hydrogen selectivity and glycerol conversion under the conditions investigated in this study. Also, the effect of WGMR, metal loading, and feed flow rate (FFR) were analyzed for the two best performing catalysts. Subsequently, effect of CeO2, MgO, and TiO2 supported Ni catalysts on hydrogen production from glycerol was studied. Effects of reaction temperature, FFR, and WGMR on hydrogen selectivity and glycerol conversion were also analyzed. Ni/CeO2 was found to be the best performing catalyst when compared to Ni/MgO and Ni/TiO2 under the experimental conditions investigated. The activation energy of glycerol reforming reaction was found to be 103 kJ/mol, and the reaction order with respect to glycerol was 0.23 over Ni/CeO2 catalysts based on the power law.

Recently there has been increasing interest in using glycerol as a substrate on steam reforming due to the increase of biodiesel production. With the increase of biodiesel production a glut of glycerol has resulted and this would be a more suitable substrate for value added production of hydrogen from reforming. Reforming biorenewable viscous fluids such as glycerol is difficult due to mass transfer limitations associated with vaporizing glycerol to gas phase before steam reforming. This study was to evaluate the feasibility of reforming electrically atomized liquid phase glycerol by means of a technique called electro-spray. It was hypothesized that reforming electrically charged glycerol nanodroplets on an oppositely charged conductive catalyst will increase the reforming performance as opposed to a neutral catalyst-substrate system. Hydrogen yield, selectivity was increased by 20%, 25% respectively when nanodroplets introduced. Exerting an electrical charge to the substrate-catalytic system significantly enhanced the reforming performance irrespective of the physical phase.

Vehicles powered by fuel cells are from an environmentalaspect superior to the traditional automobile using internalcombustion of gasoline. Power systems which are based upon fuelcell technology require hydrogen for operation. The ideal fuelcell vehicle would operate on pure hydrogen stored on-board.However, storing hydrogen on-board the vehicle is currently notfeasible for technical reasons. The hydrogen can be generatedon-board using a liquid hydrogen carrier such as methanol andgasoline. The objective of the work presented in this thesiswas to develop a catalytic hydrogen generator for automotiveapplications using methanol as the hydrogen carrier. The first part of this work gives an introduction to thefield of methanol reforming and the properties of a fuel cellbased power system. Paper I reviews the catalytic materials andprocesses available for producing hydrogen from methanol. The second part of this thesis consists of an experimentalinvestigation of the influence of the catalyst composition,materials and process parameters on the activity andselectivity for the production of hydrogen from methanol. InPapers II-IV the influence of the support, carrier andoperational parameters is studied. In Paper V an investigationof the catalytic properties is performed in an attempt tocorrelate material properties with performance of differentcatalysts. In the third part of the thesis an investigation isperformed to elucidate whether it is possible to utilizeoxidation of liquid methanol as a heat source for an automotivereformer. In the study which is presented in Paper VI a largeseries of catalytic materials are tested and we were able tominimize the noble metal content making the system more costefficient. In the final part of this thesis the reformer prototypedeveloped in the project is evaluated. The reformer which wasconstructed for serving a 5 kWe fuel cell had a highperformance with near 100 % methanol conversion and COconcentrations below 1 vol% in the product stream. The resultsof this part are presented in Paper VII. <b>Keywords:</b>methanol, fuel cell, vehicle, catalyst,copper, hydrogen, on-board, steam reforming, partial oxidation,combined reforming, oxidative steam reforming, auto-thermalreforming, zinc, zirconium, chromium, aluminium oxide,manganese, characterization, temperature programmed reduction,X-ray diffraction, chemisorption, carbon monoxide, poisoning,reformer.

<p>Vehicles powered by fuel cells are from an environmentalaspect superior to the traditional automobile using internalcombustion of gasoline. Power systems which are based upon fuelcell technology require hydrogen for operation. The ideal fuelcell vehicle would operate on pure hydrogen stored on-board.However, storing hydrogen on-board the vehicle is currently notfeasible for technical reasons. The hydrogen can be generatedon-board using a liquid hydrogen carrier such as methanol andgasoline. The objective of the work presented in this thesiswas to develop a catalytic hydrogen generator for automotiveapplications using methanol as the hydrogen carrier.</p><p>The first part of this work gives an introduction to thefield of methanol reforming and the properties of a fuel cellbased power system. Paper I reviews the catalytic materials andprocesses available for producing hydrogen from methanol.</p><p>The second part of this thesis consists of an experimentalinvestigation of the influence of the catalyst composition,materials and process parameters on the activity andselectivity for the production of hydrogen from methanol. InPapers II-IV the influence of the support, carrier andoperational parameters is studied. In Paper V an investigationof the catalytic properties is performed in an attempt tocorrelate material properties with performance of differentcatalysts.</p><p>In the third part of the thesis an investigation isperformed to elucidate whether it is possible to utilizeoxidation of liquid methanol as a heat source for an automotivereformer. In the study which is presented in Paper VI a largeseries of catalytic materials are tested and we were able tominimize the noble metal content making the system more costefficient.</p><p>In the final part of this thesis the reformer prototypedeveloped in the project is evaluated. The reformer which wasconstructed for serving a 5 kWe fuel cell had a highperformance with near 100 % methanol conversion and COconcentrations below 1 vol% in the product stream. The resultsof this part are presented in Paper VII.</p><p><b>Keywords:</b>methanol, fuel cell, vehicle, catalyst,copper, hydrogen, on-board, steam reforming, partial oxidation,combined reforming, oxidative steam reforming, auto-thermalreforming, zinc, zirconium, chromium, aluminium oxide,manganese, characterization, temperature programmed reduction,X-ray diffraction, chemisorption, carbon monoxide, poisoning,reformer.</p>

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Fuel processing is one of the essential parts for development of intermediate solid oxide fuel cells (IT-SOFC). Natural gas (methane) is considered as the most abundant and cost effective fuel for the production of hydrogen for IT-SOFC. The primary aim of this thesis is to use a novel precursor material—layered double hydroxide (LDH) – for developing a new type of cost effective, highly active and long lasting catalyst which can reform natural gas in IT-SOFC anode environment. Small amount of noble metals Pd, Rh and Pt are used as promoters to enhance the catalyst’s performance as while maintaining the cost relatively low. The research objectives are achieved by a series of studies including catalysts synthesis, characterisation and the catalytic activities. The thesis initially gives a comprehensive review on fuel cell and SOFC technology, steam methane reforming and reforming catalyst to provide better understanding of the research. Experimental studies include the effects of the synthetic conditions of the LDH precursors and thermal treatments on the physical, chemical behaviours and catalytic activities of the catalysts and promotional effects by noble metals. The LDH derived catalysts compositions, promoter quantities and operating conditions are optimised for the best performance in the IT-SOFC anode environment. A new method for the development of precursor sol for easy coating of the anode is developed and studied. The sol preparation is achieved by acid attack. The sol developed is found to produce better coating and has very high catalytic properties after activation. The catalysts developed were tested for their stability and self-activation ability to ensure its use in the commercial cells. The findings of the present study indicate that the catalysts developed show excellent catalytic performance and these catalysts have very high potential for further commercialisation in IT-SOFC.