Ce-Based Catalysts for the Selective Catalytic Reduction of NOx in the Presence of Excess Oxygen and Simulated Diesel Engine Exhaust Conditions

Abstract

A family of various cerium oxide-based catalysts were synthesized by adopting flame aerosol (FSP), coprecipitation, wet impregnation, and hydrothermal synthesis techniques. The resulting catalysts were explored for the selective catalytic reduction (SCR) of NOx using NH3 as reductant. In our studies, both the preparation method and the Ce/W ratios were found to be critical variables for successful catalyst promotion. For the industrial realization, we have scaled up the SCR activity tests. The microreactor catalytic formulations at simulated diesel engine exhaust conditions revealed that the Ce–W (1:1 atomic ratio) and Ce–W/TiO2 catalysts showed high deNOx activity, while the other catalysts’ activity was found to be rather low. Of interest is the finding that the Ce–W/TiO2/cordierite and Ce–W (1:1 atomic ratio)/cordierite formulations show impressive deNOx performance and high N2 selectivity with respect to a commercial vanadia based reference currently used for mobile applications. To gain fundamental i...