The control of nitrogen oxide (NOx) emissions is mandated by Federal, state, and local regulations. These sources are generally characterized by high-temperature combustion of fossil fuels, where organically-bound nitrogen in the fuel oxidized to form NO and small amounts of NO2 and N2. While fuel combustion to produce commercial power and motor vehicle emissions are the two largest contributors in the United States to NOx production, other sources have been targeted as well, including jet engine test cells (JETC). Existing methods to remove NOx from combustion exhausts do so only under a narrow range of conditions.
The overall objective of this project was to investigate the use of a strontium-lanthanum cobaltate catalyst (metal perovskite) for the reduction of NOx in high-temperature environments such as high-performance jet engines and exhaust manifolds of diesel or gasoline engines.
All basic research for this effort was conducted at the laboratory scale, including simulation of representative exhaust streams. The thermodynamics and kinetics of reduction by the metal perovskite catalyst were analyzed using techniques involving thermogravimetric analysis, differential scanning calorimetry, and high-temperature electrochemical cells to measure oxygen activity. Thermodynamics and kinetics of phase equilibria of the oxygen-deficient phase were modeled and reported.
Preliminary testing of catalytic activity and the design for the high space velocity reactor was completed. NOx-removal was observed for dry, oxygen-free gases at about 300°C. Evaluation of material fabrication for reactor design also was conducted. Simulation and modeling of the high temperature gas reactions were conducted to determine the simulated exhaust gas compositions to be used in the reactor for testing stoichiometric and non-stoichiometric burn conditions. This project was completed in FY 1997.
The benefit derived from this research was the determination of the feasibility and economics of using strontium-lanthanum cobaltate catalysts for reduction of NOx in high-temperature environments. The advantage of using this transition metal as a catalyst is a significant cost savings over noble metals such as platinum. This technology can be transitioned to private sector industries such as aviation and internal combustion engine manufacturers.