Abstract: A manganese oxide catalyst MnOx was prepared by the low-temperature solid phase reaction method and used for the low-temperature selective catalytic reduction (SCR) of NOx with NH3. The X-ray diffraction results show that MnOx 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 MnOx is 150.8 m2/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 NOx reaches 138.27 μmol/g. The SCR results show that the MnOx is an efficient catalyst for the SCR of NOx at low temperature. A NOx conversion of 98.25% and product selectivity for N2 of 96.6% was obtained at 80 ℃. The addition of 0.01%SO2 and 10%H2O weakens the adsorption of NOx by competition on the catalyst surface, which decreases the NOx conversion to 70% after reaction for 2.5 h. The catalyst activity can be recovered after the removal of SO2 and H2O.

Key words: manganese oxide, low-temperature selective catalytic reduction, nitrogen oxide, ammonia, low-temperature solid phase reaction