Novel MnO_x Catalyst for Low-Temperature Selective Catalytic Reduction of NO_x with NH_3

A manganese oxide catalyst MnO_x was prepared by the low-temperature solid phase reaction method and used for the low-temperature selective catalytic reduction(SCR) of NO_x with NH_3.The X-ray diffraction results show that MnO_x is a mixture of manganese oxides with poor crystallinity,which contains rodlike crystal particles(40～60 nm) and more fine amorphous particles.The BET specific surface area of the MnO_x is 150.8 m~2/g,more great than that of other unsupported catalysts ever reported,and thus its capability of adsorption is superior.In our experiments,the amount of adsorbed NO_x reaches 138.27 μmol/g.The SCR results show that the MnO_x is an efficient catalyst for the SCR of NO_x at low temperature.A NO_x conversion of 98.25% and product selectivity for N_2 of 96.6% was obtained at 80 ℃.The addition of 0.01%SO_2 and 10%H_2O weakens the adsorption of NO_x by competition on the catalyst surface,which decreases the NO_x conversion to 70% after reaction for 2.5 h.The catalyst activity can be recovered after the removal of SO_2 and H_2O.