Study On The Vanadium Phosphorus With Fe-Promoter For Selective Oxidation Of N-butane To MA

Maleic anhydride(MA)is a kind of important organic chemical raw materials and fine chemical products,has a wide application and strong market demand,while vanadium phosphorus oxide(VPO)catalyst is the most effective catalyst for n-butane selective oxidation to maleic anhydride.However,the catalysts have the problem of low activity,selectivity,and unstability.In order to improve the yield to MA,the catalysts were modified by adding metal promoters.The physicochemical properties(such as crystal structure,morphology,etc.)of the promoted VPO was well characterized and their relationship with their catalytic performances was established in details.The results are listed as follwing:1.The VPO catalyst precursors were prepared by organic process with adding Fe promoter.The effects of different metal promotors,chemical compounds,adding methods and the amount on the physicochemical properties of the catalyst were investigated in details.According to the characterization results.It was found that the addition of promoters increased the specific surface area of the catalysts,changed the P/V ratio and the valence of V,and promoted the formation of active phase(VO)2P2O7.The catalytic performance of catalysts obtained were tested with fixed-bed reactor for selective oxidation of n-butane to MA,VPO-Fe2O3-1%-A catalysts was obtained the best catalyst,which showed the conversion of n-butane about 95%and the yield of MA as high as 60%.2.Fe-bimetal modified VPO catalysts were prepared by investigating the catalytic performance of modified VPO with different metal combined with Fe.It is shown that the VPO catalyst modified with 0.7mol%Fe-Zr which was synthesized by co-precipitation had the best catalytic performance:the conversion of n-butane about 95%and the yield of MA as high as 65%.It is shown that the the catalysts adding Fe-Zr promoter can strengthen the organic phase synthesis process,promote the activity of the exposure of the crystal surface and improve the lattice oxygen content,thus effectively improve the catalytic performance.