Study On Novel Promoter Modified VPO Catalyst For Selective Oxidation Of N-butane To Maleic Anhydride

Maleic anhydride(MA)is an important chemical product and chemical raw material widely used in the production of pesticide,medicine,coatings and so on.The selective oxidation of n-butane to maleic anhydride has the advantage of low cost and low pollution,thus become the main technical route to produce MA.The vanadium phosphorus oxide(VPO)catalyst plays an important role in the production of maleic anhydride.However,the production technology of VPO catalyst is mainly monopolized by developed countries,which seriously restricts the development of maleic anhydride industry in China.Moreover,the preparation of VPO catalysts still remains with the problem of poor selectivity and environmental pollution.Attempts have been made to modify and control the VPO catalysts with the adding of metal promoter and/or organic template.In the paper,the relationship between the physical and chemical properties and the activity of modified VPO catalyst was studied,and the catalyst with high activity and selectivity was developed.The main contents and results exhibit as follows:1?The effects of differnetn species of heteropolyacid,the addition amount,and the different chemical sources of metal Mo on the VPO catalyst were studied.The physical and chemical properties of VPO and metal modified VPO catalyst were characterized,the catalytic performances of selective oxidation of n-butane to maleic anhydride were evaluated in a fixed-bed reactor.It was found that the addition of phosphomolybdic acid increased the exposure of active surface and enhanced the crystallinity of active phase.When the addition of 5%PMA promoted enriched the P on the surface,reduced the activation energy.The metal Mo of PMA was embedded in the crystal lattice of(VO)2P2O7.The VPO catalysts added by 5%PMA showd the best catalytic performance than the catalysts modified by other heteropolyacid and metal Mo.2?Glc-VPO catalyst was synthesis using glucose as an organic template to solvethe problem of small surface area and less active sites.VPO catalysts with different adding amount of glucose were characterized to analyze the physical and chemical properties.It showed that the VPO catalyst modified by glucose had changed the morphology,increased the amount of lattice oxygen.Significantly,the VPO catalyst by addition of 18%glc can increased the surface area,inhibited the formation of ?II-VOPO4 phase and observed the existence of ?-VOPO4 phase,finally the selectivity was 68 and the yield was 64%.