Selective catalytic oxidation of ammonia to nitrogen over MnO2 prepared by urea-assisted hydrothermal method

Abstract

Selective catalytic oxidation of ammonia was studied over MnO2 catalysts synthesized by urea-assisted and tranditional hydrothermal method. A contrastive research was also made to a commercial MnO2 catalyst. The catalytic performance of MnO2 for NH3-SCO was found to be connected with the properties of the catalysts which were obviously determined by the preparation methods. The best catalytic activity was achieved at 170°C over the MnO2 synthesized by urea-assisted hydrothermal method. The properties of catalysts were characterized by BET, XRD, SEM, XPS, H2-TPR and NH3-TPD techniques. And it was found that MnO2 prepared by urea-assisted synthetic method showed larger surface area and lower reduction temperature. Abundant NH3 adsorption sites and oxygen vacancies were formed on its surface compared to the other catalysts, which evidently enhanced the catalytic performance for NH3 selective oxidation.