Studies on VPO/SiO2 catalyst for selective oxidation of propane

Abstract

VPO catalyst is one of promising catalysts for selective oxidation of C4H10 and C3H8. The catalysts VPO and VPO/SiO2 with different VPO loading were prepared. Using BET, XRD, LRS, XPS, H-2-TPR and C3H8-TPD techniques, the physicochemical properties of the catalysts, such as structure, reducibility, vanadium oxidation states and V-O bond, as well as the interaction between C3H8 and the catalysts, were comparatively investigated. The catalytic performance of the catalysts in selective oxidation of C3H8 was also tested. VPO/SiO2 had higher specific surface area and reducibility than VPO. In addition, the binding energy of V 2p(3/2) on VPO/SiO2 was higher than that on VPO, which indicated that the coordination environment of V changed and Vdelta+ (4 < delta < 5) might exist on VPO/SiO2. Compared with VPO, the stronger interaction between C3H8 and VPO/SiO2 was observed. The interaction between Si and V occurred on VPO/SiO2, which modified its physicochemical properties and in return changed its catalytic performance. In the case of VPO/SiO2, (VO)(2)P2O7 was the main phase (oxidation state) and highly dispersed on SiO2. With the increase of VPO loading, the reduction temperature of the catalyst and binding energy of V 2p(3/2) changed slightly, and the intensity of V-O bond and the H-2 consumption in TPR increased, indicating that the amount of V-O species increased on the surface. On the other hand, with the increase of VPO loading, the C3H8 conversion increased while the CA Selectivity reduced, and the acrolein selectivity appeared the maximum value on 5% VPO/SiO2 catalyst.