Positive Butane Oxidation To Maleic Anhydride Vanadium Phosphorus Oxide Catalyst Additives

Various solid catalysts are obtained by calcinations of precursors prepared by impregnation method in this paper. The catalytic properties are studied to aim at acquiring maleic anhydride from n-butane. The catalytic reactions are processing in the bed-secured reactor under normal pressure. The oxygen reagent comes from the mixture of oxygen and nitrogen while n-butane is put into reactor by air. The experiment indicated that n-butane mainly transformed into maleic anhydride.on various but there exist a great deal of difference in the conversion of n-butane and selectivity of the products.The experiment manifested the (VO)₂P₂O₇ catalyst with high crystallization occupied higher selectivity in various VPO catalysts. The catalysts whose main crystalline phase are (VO)₂P₂O₇ exhibit different catalytic properties because of different precursors and activated ambience. The doping with an appropriate amount of Fe, Co and Cu composite oxide can greatly improve conversion of n-butane and selectivity of the products. The doping with an appropriate amount of Ce-Zr composite oxide can significantly improve the catalytic performance of (VO)₂P₂O₇ catalyst, whereas when the promoter is added by impregnation ,the selectivity to products is lower than in the unpromoted catalyst. The catalysts , which hold different carrier and ratio of V/P performance very differently.The evaluation of catalysts under various temperatures, space velocity and the concentration of oxygen and n-butane indicated that the appropriate condition must be fulfilled in order to meet the optimization of catalytic properties.The reasons why various catalysts performance differently are discussed in view of the result of evaluation experiment, XRD, IR and the average value of vanadium. It is regarded that the good catalysts on which n-butane transformed into maleic anhydride must possess optimum ratio of V^V/ V^IV, while V^IV existed in the phase of (VO)₂P₂O₇ as more as possible, in order toform the effective circulation of V^IV-V^V-V^IV.