Regulating the Selective Dispersion of Tungsten Oxide to Promote Propane Combustion on Pt-Nanoparticle Catalysts Supported on WO<i>_x</i>/ZrO₂ by Tuning the Zirconia Crystal Phase

Abstract

Low-temperature catalytic oxidation of propane on Pt-based catalysts is of paramount importance but remains a major challenge for the emission control of volatile organic compounds (VOCs). Here, we report the promoting effects of doped WOx on 0.5 wt % Pt/ZrO2 catalysts for propane oxidation, which strongly depended on the crystal structure of ZrO2. Among them, 0.5 wt % Pt/WOx/t-ZrO2 shows the highest catalytic activity, the T90 is 216 °C, which is about 155 and 80 °C lower than that of Pt/t-ZrO2 and Pt/WOx/m-ZrO2, respectively, and the turnover frequency (TOF) of Pt/WOx/t-ZrO2 at 190 °C is about 3 times that of Pt/WOx/m-ZrO2. Multicharacterization results show that compared with Pt/WOx/m-ZrO2, doped WOx can be highly dispersed on t-ZrO2 and form the solid solution-like (Zr1–xWxO2+x/2) nanolayer structure at the catalyst surface, which produces additional strong Brønsted acid sites and metallic Pt (Pt0) sites via an electron transfer from W to Pt on Pt/WOx/t-ZrO2. The synergistic effect of Pt0 and strong acidity at the Pt–Zr1–xWxO2+x/2 interface facilitates the rapid removal of surface intermediates including carboxylate and CO generated during the reaction and promotes C3H8 oxidation on Pt/WOx/t-ZrO2. This work highlights a direction for the design of high-efficiency metal oxide-modified Pt/ZrO2 nanoscale catalysts by changing the crystal structure of the ZrO2 support for the removal of VOCs.