Zr-Doped β-MnO2 for Low-temperature Selective Catalytic Reduction of NO by NH3: Preparation, Characterization and Performance

Nanowire-MnO2 and a series of Zr-doped MnO2 catalysts with different Zr/Mn molar ratios were successively prepared by hydrothermal and impregnation methods. The Zr-doped MnO2 catalyst with Zr/Mn molar ratio of 0.04 and calcination temperature of 400 degrees C, proved to be the optimal that possessed the highest low-temperature denitration efficiency. It showed the NO conversion of ~92 % and N-2 selectivity of ~80 % at 150 degrees C. Characterization results demonstrated that the main active phase of the catalyst was beta-MnO2, Zr atoms interacted with Mn atoms, and Zr doping increased the structural defects, oxygen vacancies and weak acid sites, which effectively enhanced the low-temperature denitration activity and N-2 selectivity of beta-MnO2, also improved the water and sulphur resistance to some extent.