Catalytic Reduction of Nitrogen Oxides from Stationary PowerSources Using Methane

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This project examines the feasibility of reducing emissions of nitrogen oxides from stationary power sources by including a catalytic reburn step in the process. The reburn chamber would be incorporated into the stack of a boiler or into a heat- recovery steam generator following a gas turbine, and would incorporate heterogeneous catalysts capable of generating methyl radicals from natural gas (methane) injected into the exit stream of the combustor. The ability of methyl radicals to reduce nitrogen oxides is already well established. In this study, two families of catalysts known to generate methyl radicals from methane are used: lithium-doped zinc oxide and magnesium oxide, and rare- earth oxides such as lanthana. Catalytic studies and adsorption measurements provide specific activities, activation energies, and kinetic rate expressions. Infrared spectroscopy done in situ is used to characterized the surface species on the most active catalysts. Successful application of this concept to power generating processes would result in an enormous decrease in nitrogen oxide emissions and would probably eliminate acid rain from power generation as a major environmental problem. It would also obviate the need for the more expensive and more cumbersome processes involving ammonia that are currently being used. Application to other industrial sources nitrogen oxides is also envisioned.