In situ electrical conductivity study of Pt-impregnated VOx/γ-Al2O3 catalysts in propene deep oxidation

A series of Pt-VOx/γ-Al2O3 catalysts with vanadium loading corresponding to 5 and 20 wt% V2O5 was prepared by impregnation method. The catalytic performance of the obtained materials was investigated in propene deep oxidation reaction. The catalysts were characterized by N2 physisorption, chemical analysis, X-ray diffraction (XRD), temperature-programmed reduction (TPR), electron paramagnetic resonance (EPR) spectroscopy, and UV–Vis diffuse reflectance spectroscopy. Alternating current (AC) electrical conductivity measurements (differential steps technique) were performed in situ during propene oxidation, using an own design reactivity cell. The variation in the measured electrical conductance brings information about the relative oxidation state of the catalyst's surface during reaction. It was found by TPR, EPR, and UV–Vis that the presence of platinum facilitates the reduction of V5+ to V4+ species. The catalytic performance of the investigated catalysts was discussed in relation to their structure, reducibility, and conductance.