Studies on generation mechanism of acid site on the surface of ceramics

采用酸催化反应和结构表征技术，研究了不同负载、不同温度下氧化铝负载金属氧化物（Nb2O5/Al2O3、Ta2O5/Al2O3、MoO3/Al2O3、WO3/Al2O3）催化剂的酸性能。评价了酸性质、结构和催化性能之间的关系。焙烧温度和金属氧化物的负荷量对催化活性和溴化酸位点的数量都有影响。高温煅烧（> - 1100k）产生了布朗酸性质。酸催化反应的活性与bronsted酸性成正比，表明这些反应发生在bronsted酸位点。具有扭曲八面体对称性的金属氧化物被加载成二维单层结构域，这些结构域覆盖了大部分氧化铝表面。在氧化钨单层结构域之间的边界处产生了溴化酸位。

The acid properties of a series of alumina-supported metal oxides (Nb2O5/Al2O3, Ta2O5/Al2O3, MoO3/Al2O3, WO3/Al2O3) catalysts with various loadings and calcined at various temperatures were investigated by acid-catalyzed reactions, and structural characterization techniques. The relationships between acid properties, structures, and catalytic performances are evaluated. Both the catalytic activity and amount of Broensted acid sites depend on calcination temperature and metal oxide loading amount. High temperature calcination (> 1100 K) generated Broensted acid property. The activities for acid-catalyzed reactions were proportional to Broensted acidity, indicating that these reactions occurred on the Broensted acid sites. Metal oxide having distorted octahedral symmetry was loaded as two-dimensional monolayer domains and these domains covered most of the alumina surface. Broensted acid sites are generated at the boundaries between tungsten oxide monolayer domains.