Propane dehydrogenation over vanadium-doped zirconium oxide catalysts

Abstract

Bulk ZrO2 is a highly active and selective catalyst for dehydrogenation of propane (PDH), in which co-ordinatively unsaturated Zr cations (Zr-cus(4+)) serve as active sites. Substitution of dopant ions into Zr lattice can improve its catalytic activity by generating more Zr-cus(4+) sites. In this work, a series of vanadium-doped ZrO2 metal oxides (VZrO-x) have been prepared and the influences of vanadium content on their properties have been systematically investigated. Various characterization techniques showed that an appropriate amount of vanadium dopant helps more Zr-cus(4+) sites to be created by a structural transformation and H-2 pretreatment. However, excess vanadium dopant led to a negative effect on the catalytic activity owing to the formation of bulk-like V2O5 crystallites. The catalytic activity of VZrO-x is well correlated with the amount of Lewis acid sites because Zr-cus(4+) cations correspond to Lewis acid sites. The VZrO-8 catalyst exhibited two times higher activity than pure ZrO2. Moreover, for repeated cycles the activity was totally recovered by oxidative regeneration followed by reductive pretreatment. Finally, the performance test results showed that H-2 co-feeding can further enhance the activity by suppressing coke deposition during PDH.