【摘要】 采用固体核磁共振及密度泛涵理论计算方法研究了MoO3/SnO2催化剂的结构和性质及其固体酸性.结果表明:在这种催化剂中,钼组分主要是散布在氧化锡表面而非大幅度融入氧化锡晶格结构中;Brnsted酸位和Lewis酸位同时存在,酸性强于沸石分子筛(如HY和HZSM-5),但酸位浓度相对较低.理论方法计算的催化剂上吸附丙酮的13C化学位移与试验结果很接近,证实了所提出的Brnsted酸位结构为—Mo—(OH)—Sn—.固体核磁共振试验还证实了这种负载氧化物的氧化性,最后提出了Lewis酸位才是其氧化反应的活性中心.更多还原

【Abstract】 Research on the structure and properties,especially the solid acidity and catalytic nature,of molybdenum oxide supported on tin oxide,by use of solid-state nuclear magnetic resonance(SSNMR) spectroscopy and density functional theory(DFT) calculation,were performed.As demonstrated by solid-state NMR experiments,Brnsted as well as Lewis acid sites are created in our MoO3/SnO2 sample.Overall acid is stronger than those of zeolites,e.g.,HY and HZSM-5,in strength,though concentration of acid sites is relatively lower.The DFT computational 13C chemical shift for acetone absorbed on MoO3/SnO2 is in well agreement with the experimental value,which confirms the local structure of —Mo—(OH)—Sn— for Brnsted acid site.Reducibility of this supported metal oxide is also demonstrated by solid-state NMR experiments and active oxidation center of this catalyst is proposed as well.更多还原