Regulating the Selective Dispersion of Tungsten Oxide to Promote Propane Combustion on Pt-Nanoparticle Catalysts Supported on WO<i><sub>x</sub></i>/ZrO<sub>2</sub> by Tuning the Zirconia Crystal Phase
Chuntao Shao, Jie Yang, Yang You, Xuan Tang, Jie Tang, Li Wang, Yao Cui, Wangcheng Zhan, Yanglong Guo, Yanglong Guo, Yun Guo, Yun Guo
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.