自蔓延高温燃烧合成法制备CeWTiOx催化剂及其NH3-SCR性能

摘要

A series of CeWTiOx catalysts were prepared by self-propagating high-temperature synthesis method,and their NH3-SCR activities were evaluated.X-ray diffraction,N2 adsorption-desorption,H2-temperatureprogrammed reduction,X-ray photoelectron spectroscopy and NH3-temperature-programmed desorption were performed to investigate the relationship between the catalyst activity and its physicochemical properties such as crystalline phase,specific surface area,redox ability and acidity.The results showed that 80％ of NO conversion could be reached on the Ce40W10TiOx catalyst sample in a range of 150-430 ℃.NO conversion of Ce40W10TiOx could be kept above 97 ％ in SO2 atmosphere.The characterization indicated that the excellent low temperature activity and SO2 resistance of Ce40W10TiOx were mainly associated with the tungsten doping.The existence of tungsten weakened the strength of Ce-O bond,lowered the crystallinity and crystal size of CeO2,increased the surface active oxygen content and the acid sites,thus improved the NH3-SCR performance of the catalyst.%采用自蔓延高温燃烧合成法制备了CeWTiOx系列催化剂并考察了其氨选择性催化还原NOx(NH3-SCR)性能.利用X射线衍射、N2吸附-脱附、H2程序升温还原、X射线光电子能谱、NH3程序升温脱附表征和分析了催化剂晶相、结构、氧化还原能力和酸性强度与其活性之间的关系.结果表明,Ce40W10TiOx催化剂在150-430℃NO转化率可达80％以上,含硫条件下200℃NO转化率可保持在97％左右.结果表明,该催化剂的低温活性和抗硫性能主要与W的掺杂有关.钨的存在减弱了Ce-O键的强度,降低了CeO2的结晶度和减小了晶粒粒径,增加了催化剂表面活性氧含量和酸量,提高了其性能.