Dielectric barrier discharge plasma modified Pt/CeO2 catalysts for toluene oxidation: Effect of discharge time

This work demonstrated that a dielectric barrier discharge plasma was applied to modify the performance of catalyst. The Pt/CeO2 catalyst was treated with various plasma discharge time to reveal the effect of plasma on the performance of Pt/CeO2 catalyst for toluene oxidation. It is interesting that two volcanic peaks appeared at discharge time of 30 min (Pt/CeO2-PT3) and 3 h (Pt/CeO2-PT6). Compared to Pt/CeO2 without plasma treatment, their catalytic activities (T90) decreased by 24 °C for Pt/CeO2-PT3 and 34 °C for Pt/CeO2-PT6, respectively. By contrast, the Pt/CeO2-PT5 (2 h) showed the lowest activity due to the surface carbon deposition. We demonstrated that the plasma discharge time significantly affects the Pt particle size, CeO2-rod length, oxygen vacancies, and redox ability of the Pt/CeO2 catalyst by using the characterizations of X-ray power diffraction patterns (XRD), specific surface area (BET), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and hydrogen temperature-programmed reduction (H2-TPR). The linear relationship between catalytic activities and turnover frequency values (TOFPt and TOFOv) were observed in the discharge time ≤1 h. Furthermore, we found that discharge time has a more profound impact on oxygen vacancy than Pt particle.