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Propane Fuel Cells: Selectivity for Partial or Complete Reaction

DOI: 10.1155/2014/485045

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Abstract:

The use of propane fuel in high temperature (120°C) polymer electrolyte membrane (PEM) fuel cells that do not require a platinum group metal catalyst is being investigated in our laboratory. Density functional theory (DFT) was used to determine propane adsorption energies, desorption energies, and transition state energies for both dehydrogenation and hydroxylation reactions on a Ni(100) anode catalyst surface. The Boltzmann factor for the hydroxylation of a propyl species to form propanol and its subsequent desorption was compared to that for the dehydrogenation of a propyl species. The large ratio of the respective Boltzmann factors indicated that the formation of a completely reacted product (carbon dioxide) is much more likely than the formation of partially reacted products (alcohols, aldehydes, carboxylic acids, and carbon monoxide). That finding is evidence for the major proportion of the chemical energy of the propane fuel being converted to either electrical or thermal energy in the fuel cell rather than remaining unused when partially reacted species are formed. 1. Introduction Fuel cells convert the chemical energy of a fuel into electrical energy. Theoretically they can produce more electrical energy from a fuel than either batteries or combustion processes. Propane was the fuel investigated for the fuel cells described in this work. Trucks currently deliver liquefied petroleum gas (LPG) (mostly propane) in rural areas where roads exist. The cost of delivering conventional electrical power in rural areas is approximately an order of magnitude greater than that in urban areas, even though the price charged by utility companies for electrical power is often similar. Therefore, a greater capital cost for fuel cells can be accepted in rural areas than in urban areas. This indicates that a niche market for propane fuel cells in rural areas would be profitable prior to a profitable market in urban areas. Most fuel cells use either hydrogen or methanol as the fuel. They have several disadvantages. Unfortunately no infrastructure exists for their distribution and storage. Furthermore they are both manufactured from natural gas (primarily methane) using complex reactor systems that have a large capital cost. They also have a large operating cost because 25% of the natural gas is consumed to provide the endothermic heat for the steam reforming reaction. Hydrogen gas requires sophisticated storage systems [1]. None of those disadvantages occur when propane reacts directly at the anode of a fuel cell. The type of propane fuel cell we are investigating

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