Development of methane oxidation catalysts for different gas turbine combustor concepts
Abstract: Due to continuously stricter regulations regarding emissions from power generation processes, development of existing gas turbine combustors is essential. A promising alternative to conventional flame combustion in gas turbines is catalytic combustion, which can result in ultra low emission levels of NOx, CO and unburned hydrocarbons. The work presented in this thesis concerns the development of methane oxidation catalysts for gas turbine combustors. The application of catalytic combustion to different combustor concepts is addressed in particular.The first part of the thesis (Paper I) reports on catalyst development for fuel-lean methane combustion. The effect on catalytic activity of diluting the reaction mixture with water and carbon dioxide was studied in order to simulate a combustion process with exhaust gas recirculation. Palladium-based catalysts were found to exhibit the highest activity for methane oxidation under fuel-lean conditions. However, the catalytic activity was significantly decreased by adding water and CO2, resulting in unacceptably high ignition temperatures of the fuel.In the second part of this thesis (Paper II), the development of rhodium catalysts for fuel-rich methane combustion is addressed. The effect of water addition on the methane conversion and the product gas composition was studied. A significant influence of the support material and Rh loading on the catalytic behavior was found. The addition of water influenced both the low-temperature activity and the product gas composition.
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