Effects of dielectric barrier discharge plasma on the catalytic activity of Pt/CeO2 catalysts

Abstract

CeO2 nanorod was synthesized by a hydrothermal method and impregnated with Pt to synthesize Pt/CeO2 catalysts, which were modified by dielectric barrier discharge plasma. The modified CeO2 and Pt/CeO2 were characterized by XRD, STEM, N2 adsorption/desorption, CO pulse chemisorption, XPS, H2-TPR, O2-TPD and UV-Raman spectroscopy techniques. After the plasma treatment, the T90 value of (Pt/CeO2)-P catalyst decreased from 287 °C to 208 ℃ for toluene oxidation. This significantly changed activity of catalyst indicated that plasma has greatly impacted its performance. More and larger notches on surface and broken fragments were found from STEM analysis. In addition, smaller Pt particle size and higher dispersion of nanoparticles was found on (Pt/CeO2)-P, which was characterized by CO pulse chemisorption and TEM analysis. In addition, Pt/(CeO2-P) and (Pt/CeO2)-P possessed higher concentration of oxygen vacancies and Ce3+, which was observed by UV-Raman spectroscopy and XPS. Moreover, according to TPR results, the interaction between Pt and CeO2 was obviously strengthened, which led to a lower reduction temperature after plasma treatment. After plasma treatment, the (Pt/CeO2)-P presented the highest activity due to it possessing the highest TOFPt and TOFov values of 9.88 × 10−4 s−1 and 9.49 × 10−5 s−1, respectively, and lower activation energies of 63.8 kJ mol−1. Furthermore, the toluene conversion of (Pt/CeO2)-P without significantly decreasing for working at least 50 h and under 9.6 vol% water vapor.