Synthesis of MnO sub(x)-CeO sub(2).NO sub(x) catalysts by polyvinylpyrrolidone-assisted supercritical antisolvent precipitation

A series of MnO sub(x)-CeO sub(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 sub(x)-CeO sub(2) were investigated. A solid solution was obtained at each experimental condition and the highest surface area of 107.6 m super(2)/g was obtained at the Mn/Ce molar ratio of 3:5 and the calcination temperature of 400 degree C. Low-temperature selective catalytic reduction of emissions of nitrogen oxides, namely NO, NO sub(2), and N sub(2)O (deNO sub(x)) with ammonia (NH sub(3)) to convert them into nitrogen and water, was used as model reaction to evaluate MnO sub(x) -CeO sub(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 sub(2) selectivity) was obtained at the Mn/Ce molar ratio of 1/1 and the calcination temperature of 400 degree C, which was attributed to the combination of high surface area and high redox performance of the catalyst.