掺Ag对氧化锰八面体分子筛催化CO氧化性能的影响

采用回流法在酸性介质中合成了掺杂贵金属Ag的氧化锰八面体分子筛(OMS-2).利用X射线衍射、低温N2吸附、透射电子显微镜及程序升温脱附(TPD)等技术对固体材料的结构进行了表征,考察了材料对CO氧化反应的催化性能,以及Ag的掺杂对该反应的影响.结果表明,合成的OMS-2材料属于cryptomelane一维隧道结构,适量Ag的掺杂使分子筛的有序性得到改善,孔径更均一.Ag的加入还能明显提高催化剂的反应活性.O2-TPD和CO-TPD实验表明,Ag的引入使材料对CO的吸附性能及晶格氧的扩散能力得到显著增强,这是提高催化剂对CO氧化催化能力的主要原因.

Effect of Doped Ag on Performance of Manganese Oxide Octahedral Molecular Sieve for CO Oxidation

A series of Ag-doped manganese oxide octahedral molecular sieves(OMS-2) were synthesized by the reflux method in an acid medium.The structure of the catalysts was characterized by X-ray diffraction,N2 adsorption,transmission electron microscopy,and temperature-programmed desorption(TPD).The effect of the promoter Ag was deduced.The results showed that the catalysts have the typical cryptomelane structure with a one-dimensional channel.The doping with Ag resulted in Ag/OMS-2 catalysts with a higher specific surface area and narrower pore size distribution than OMS-2.The catalysts showed excellent catalytic activity for CO oxidation and the catalytic activity was increased after Ag introduction.O2-TPD and CO-TPD results showed that this was because the doping with Ag increased the rate of CO adsorption and the diffusion of lattice oxygen ions.