钒钛催化剂制备工艺参数对其表面结构与催化性能的影响

研究V2O5/TiO2催化剂的制备工艺,如载钒量、煅烧时间、助催化剂和浸渍次数等,对催化剂表面结构及催化分解气相邻二氯苯的影响。采用漫反射紫外光谱（DRUVS）、X射线衍射（XRD）、BET等方法对催化剂进行表征。结果表明,随着载钒量的增大,催化剂表面活性物质含量增多,催化性能增强;延长煅烧时间会导致催化剂的团聚增加、比表面积减少,但有利于催化剂表面生成低聚态活性钒和V4＋,从而提高其催化活性;添加助催化剂WO3和采用多次浸渍均能抑制活性钒的团聚,促进表面低聚态活性钒的分散;单聚和低聚钒酸盐是VOx/TiO2催化剂的活性物质,而高聚钒对催化分解气相邻二氯苯有抑制作用。

Effect of preparation processes of vanadium-titanium catalyst on its surface structure and catalytic property

The effect of preparation processes of the vanadium-titanium catalyst such as vanadium content,calcination time,additive and number of impregnation times on the catalyst＇s surface structure and property for catalytic combustion of o-dichlorobenzene were investigated.The catalyst was characterized by means of diffuse reflectance UV spectroscopy（DRUVS）,X-ray diffraction spectrum（XRD） and the BET technique.The results show that the active sites on the surface of the catalyst increase with the increase in V loading and the catalytic performance is enhanced.Prolonging calcination time results in the aggregation of vanadium species and a decrease in the specific surface area,yet is beneficial to producing oligomeric active vanadium and hence improving the catalytic performance.Both tungstic oxide additive and multiple impregnation method are beneficial to generating well dispersed active vanadium and inhibiting the aggregation and polymerization of surface vanadium.Further results of DRUV indicate that monomer and oligomeric vanadate are the active sites of the VOx/TiO2 catalyst and polymeric vanadium has a negative effect on the catalytic decomposition of o-dichlorobenzene.