载体酸碱性对钒基催化剂丙烷氧化脱氢性能的影响及其IR和EPR研究

Abstract

[中文摘要]应用ＩＲ和低温ＥＰＲ等方法研究了载体酸碱性对钒基催化剂丙烷氧化脱氢性能的影响。从ＶＳｎＯ、ＶＳｉＯ、ＶＴｉＯ、ＶＡｌＯ到ＶＭｇＯ，随着载体的碱性增强，丙烷转化率和丙烯选择性均提高，然而从ＶＭｇＯ、ＶＣａＯ、ＶＳ－ｒＯ到ＶＢａＯ，随着载体碱性的进一步增强，丙烯选择性仍提高，但丙烷转化率显著降低。这些结果表明，只有适度增强催化剂的碱性，才有利于生成Ｖ４＋离子，减少表面碳酸盐的生成，并缩短脱氢中间体在催化剂上的停留时间和促进丙烯的脱附，减少Ｃ－Ｃ键断裂和转化为ＣＯｘ的机会，从而有利于丙烷氧化脱氢生成丙烯。[英文摘要]The effects of acidity and basicity of the supports on the performance of Vbased catalysts for oxidative dehydrogenation of propane were investigated by IR and EPR. Propane conversion and propene selectivity increased with an increase of basicity of the supports in the order:VSnO→VSiO→VTiO→VAlO→VMgO.However, with a further increase of basicity in the order:VMgO→VCaO→VSrO→VBaO, propane conversion decreased remarkably although propene selectivity remained increasing.These results indicated that only moderate strengthening basicity can be beneficial to form v4+ ions,reduce surface carbonate formation,shorten the reteution time of dehydrogenated intermediate on the catalyst,promote desorption of propene hence favourable for propane dehydrogenation to propene.