SnOx-CeO2-MnOx/球状活性炭催化剂低温选择性催化还原NO

SnO_x-CeO_2-MnOx-loaded spherical activated carbons for the selective catalytic reduction of NO

制备了系列锡氧化物改性SnOx-CeO2-MnOx/球状活性炭（SAC）催化剂,研究了锡氧化物对催化剂脱硝活性的影响机制,并结合N2吸附、XRD、XPS和NH3-TPD等技术对催化剂物理化学性质进行表征。结果表明,向CeO2-MnOx/SAC中添加适量SnOx后明显降低催化剂在低温区80-120℃的脱硝活性,但在200-280℃温度范围内Sn/Mn摩尔比为0.25的SnOx-CeO2-MnOx/SAC催化剂对NO的转化率高于95.8%。添加适量Sn O2不仅不影响锰氧化物在载体表面的高分散性,而且可以改善CeO2分散性;添加SnO2提高了催化剂表面酸性,尤其是增加了催化剂表面中强酸位,有利于促进NH3的吸附和活化脱氢,从而提高SnOx-CeO2-MnOx/SAC较高温区SCR活性。

A series of SnOx-CeO2-MnOx-loaded spherical activated carbons（SACs） with different Sn/Mn molar ratios were preparedas catalysts for the selective reduction of NO and the influence of the SnOx contenton their catalytic activities was investigated.The physicochemical properties of the catalysts were characterized by nitrogen adsorption,X-ray diffraction,X-ray photoelectron spectroscopy and temperature-programmed NH3 desorption.Results indicate that the addition of an appropriate amount of SnOx to the CeO2-MnOx-loaded SACs significantly reduces NO reduction activity in the low temperature range 80-120 ℃.However,the NO conversion is higher than 95.8% in the temperature range 200-280℃ when the Sn/Mn ratio of the catalyst is 0.25.The SnOx addition increasesthe acidity of the catalyst surface,especially the number of the medium-strong acid sites,which favors the adsorption anddehydrogenation of NH3.An appropriate amount of SnO2 increasesthe dispersion of CeO2 on the support with out sacrificing the high dispersion of MnOx.These factors jointly contribute to the increaseof NO reduction activity over the SnOx-CeO2-MnOx-loaded SACs at temperatures from 200 to 280℃.