V-Mo系催化剂在不同活化气氛下的性能研究

Study on properties of VMo-based catalysts under different activation conditions

制备了V-Mo-O系列苯氧化制顺酐催化剂,考察了该系列催化剂在N2、空气、密闭等不同氛围下活化处理后催化剂的性能变化,并采用成熟的带原料苯活化催化剂的方法对催化剂进行活化,将催化剂的性能结果与前面不同活化氛围下催化剂的性能结果进行比较。结果发现,在密闭气氛条件下,450℃活化处理的催化剂的活性和选择性很好。通过XRD、SEM、XPS-EDX、TPR和BET等结构表征,发现不同活化氛围下催化剂微观结构发生明显的变化,V元素价态也发生变化,使催化剂的还原度不同,从而活性相的形成不同,进而对催化剂的活性和选择性产生影响。

Abstract： The V-Mo-O based catalysts for oxidation of benzene to maleic anhydride were prepared in this paper. The effect of different atmospheres,such as N2 ,air, the airtight condition, and so on,on the properties of V-Mo-O based catalysts were studied. The properties of the catalysts activated inside the reactor with benzene and air were compared with those activated under different atmosphere mentioned above. The results show that, the catalysts have optimal activity and selectivity under airtight condition at 450℃. The significant difference of the microstructures of the catalysts activated under different atmosphere can be observed by XRD, SEM-EDX, XPS, TPR and BET. Under reduced atmosphere, the V^（5＋） is reduced to V^（4＋） , while in oxidation atmosphere, V is almost all in V^（5＋） , which indicates that, the difference in reduction degree of V-Mo-O based catalysts leads to the difference in formed active phase,thus affects their corresDonding activity and selectivity.