丙烷选择氧化制丙烯醛VTeO/SiO_2催化剂的反应性能与结构表征

Catalytic Performance and Characterization of VTeO/SiO_2 Catalysts for Selective Oxidation of Propane to Acrolein

运用浸渍法制备了一系列不同组成的VTeO/SiO2催化剂,并采用XRD、TPR、Raman等技术,研究了VTeO/SiO2催化剂的结构及其对丙烷选择氧化制丙烯醛反应的催化性能.结果表明,在VOx/SiO2催化剂中添加适量Te,丙烯醛选择性和收率显著提高.VTeO/SiO2催化剂与单组分催化剂结构明显不同.由于V、Te之间的相互作用,在VTeO/SiO2催化剂表面由[TeO4]、[Te2O5]和多钒酸盐类物种形成一种高分散的无定形结构.这种结构可能由于催化活性中心的高度分散而有利于丙烷选择氧化生成丙烯醛.

The structures and catalytic performances of VTeO/SiO2 catalysts for selective oxidation of propane to acrolein were studied by XRD,TPR, Raman and XPS techniques. Under the reaction conditions studied, 3V/SiO2 catalyst showed a high activity for propane conversion, but the products were mainly Ca H6 and COx. With addition of Te to the catalyst,conversion of propane and selectivities to Ca H6 and COx were decreased, whereas the selectivity to acrolein was notably increased. The maximal yield of acrolein of 6. 6% was obtained on 3V0. 5Te/SiO2 catalyst under 520℃. XPS results indicated that the VTeO/SiOz, VOx/SiO2 and TeOx/SiO2 catalysts were identical in oxidation states of V^5＋ and Te^4＋ ,but the catalysts were distinctly different in their structures,as demonstrated by the results of XRD,TPR and Raman. Due to the interaction between V and Te, VTeO/SiO2 catalysts presented higher dispersion of both V and Te oxides. On the catalysts, amorphous structures were formed by highly dispersed [TeO4] structural units, [Te2O5] groups,as well as vanadate- and/or polyvadate-like species. Considering the high dispersion of the active sites in the disorder structures,the structures were assumed to be beneficial to the formation of acrolein from propane oxidation.