Surface phase transformation of ZrO2 in VOx/ZrO2 catalysts for boosting propane nonoxidative dehydrogenation

The nanocatalysts of VOx deposited on ZrO2 supports with single monoclinic (ZrO2-M), tetragonal (ZrO2-T), and binary monoclinic-tetragonal (ZrO2-MT) phase were synthesized. VOx/ZrO2-MT catalysts exhibit better performance during propane nonoxidative dehydrogenation than VOx/ZrO2-M and VOx/ZrO2-T catalysts. Among VOx/ZrO2-MT catalysts, the conversion and deactivation rate constant of VOx/ZrO2-M31T69 catalyst is 35.2% and 0.22 h(-1), respectively. The promoting role of ZrO2-MT is revealed by experiments and theoretical calculations. The MT-mixed phase structure in VOx/ZrO2-MT catalyst improves the structural properties and dispersion of VOx. The tetragonal-monoclinic transformation on the ZrO2-MT surface facilitates VOx reduction and produces additional V3+ active sites. The highly dispersed V3+ sites on the ZrO2-MT surface accelerate C-H bond breaking and boost the desorption of propylene, which is the key reason for enhancing activity and stability during the reaction, respectively. Insight into the role of surface phase transformation of ZrO2-MT is expected to obtain high-efficient catalysts further.