Cyclohexane Gas-solid Phase Catalytic Oxidation System Maleic Anhydride And Acetic Acid Solid Catalyst

Various solid catalysts are obtained by calcination of precursors prepared by precipitation, coprecipitation and impregnation method in this paper. The catalytic properties are studied to aim at acquiring maleic anhydride and acetic acid from cyclohexane. The catalytic reactions are processing in the bed-secured micro-reactor under normal pressure. The oxygen reagent comes from the mixture of oxygen and nitrogen while gas-cyclohexane is put into reactor by nitrogen. The experiment indicated that cyclohexane mainly transformed into maleic anhydride and acetic acid on various but there exist a great deal of difference in the conversion of cyclohexane 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 Ce-Zr composite oxide can significantly improve the catalytic performance of (VO)2P2O7 catalyst. The appropriate amount of incorporated molybdenum by impregnation can improve the catalytic performance of (VO)2P2O7 catalyst ,whereas when the promoter is added by coprecipitation ,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 cyclohexane 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, FT-1R and the average value of vanadium It is regarded that the good catalysts on which cyclohexane transformed into maleic anhydride and acetic acid must possess optimum ratio of vV/VIV while VIV existed in the phase of (VO)2P2O7 as more as possible, in order to form the effective circulation of VIV-VV-VIV. The possible mechanism of catalytic reaction is advanced and the initial explanation is given in the last...