Roles of V−O sites for non-oxidative propane dehydrogenation over supported vanadium oxides

Supported vanadium oxides (VOx) are alternative candidates for non-oxidative propane dehydrogenation (PDH) owing to their competitive performance. This paper describes the roles of V−O sites on PDH over monomeric VOx species supported on ZrO2, Al2O3 and SiO2. With the control of pre-reduction, stable structures of V−O sites are obtained for PDH, including V−O-support (V−O−S), V−OH and V=O sites. By tuning the V densities over individual support, the propylene formation rate shows a linear correlation with the number of the V−O−S site, which indicates the V−O−S site plays a decisive role in PDH rather than V−OH and V=O sites. Moreover, the specific activity per V−O−S site over ZrO2 (8.2 × 10−3 s−1) is higher than those over Al2O3 (6.7 × 10−3 s−1) and SiO2 (2.8 × 10−3 s−1), due to the discrepant Lewis acidity of various V−O−S sites. This research provides a fundamental insight into the intrinsic nature of V−O sites for non-oxidative propane dehydrogenation.