Synthesis of MnOx–CeO2·NOx catalysts by polyvinylpyrrolidone-assisted supercritical antisolvent precipitation

A series of MnO x –CeO 2 binary oxide catalysts were synthesized by polyvinylpyrrolidone-assisted supercritical antisolvent precipitation and the effects of the manganese (Mn)/cerium (Ce) molar ratio and calcination temperature on the structure and properties of MnO x –CeO 2 were investigated. A solid solution was obtained at each experimental condition and the highest surface area of 107.6 m 2 /g was obtained at the Mn/Ce molar ratio of 3:5 and the calcination temperature of 400 °C. Low-temperature selective catalytic reduction of emissions of nitrogen oxides, namely NO, NO 2 , and N 2 O (deNO x ) with ammonia (NH 3 ) to convert them into nitrogen and water, was used as model reaction to evaluate MnO x –CeO 2 catalytic performance. It is found that the activity first increased and then decreased with increasing Mn content and decreased with increasing calcination temperature. The highest catalytic activity (93.3% NO conversion and 100% N 2 selectivity) was obtained at the Mn/Ce molar ratio of 1/1 and the calcination temperature of 400 °C, which was attributed to the combination of high surface area and high redox performance of the catalyst.