V_2O_5基多元催化剂的表面酸性与均四甲苯催化氧化选择性和活性的关系

Relationship of Surface Activity of V_2O_5-Based Catalysts with Selectivity and Activity in Catalytic Oxidation of Durene

以均四甲苯气相催化氧化制备均苯四甲酸二酐为研究对象,通过测定催化剂表面酸性,研究了以V2O5为基础,加入其它金属氧化物的多元组分催化剂的表面酸性与氧化选择性和活性的关系;同时研究了催化剂的组成、V2O5还原度和焙烧温度对其酸性的影响。结果表明,催化剂的表面酸性与氧化选择性和活性有关,V2O5-TiO2-Na2O-P2O5是酸性催化剂;对于催化剂V2O5-TiO2-Na2O-P2O5来说,当V5+ Vtotal的值接近54 3%时,催化剂的表面酸性最高,当此催化剂在温度为550℃下焙烧,所得催化剂的酸度有一最大值。

In this paper,the relationship of surface activity of V_2O_5-based catalysts with selectivity and activity in catalytic oxidation of durene was studied.In the catalytic reaction,pyromellitic dianhydride was prepared by catalytic vapor-phase oxidation of durene over V_2O_5-based catalysts.The effects of constitute of catalysts,reduction degree of V_2O_5 and the calcination temperature were investigated.It was found that the surface acidity of the catalysts was related to the oxidation selectivity and activity and V_2O_5-TiO_2-Na_2O-P_2O_5 was an acidic catalyst;when the value of V+5/Vtotal is close to 53.4% for V_2O_5-TiO_2-Na_2O-P_2O_5,the surface acidity of the catalyst is the highest and when V_2O_5-TiO_2-Na_2O-P_2O_5 is calcinated at 550℃,the surface acidity of the resulting catalyst has the highest value.