Electric field assisted benzene oxidation over Pt-Ce-Zr nano-catalysts at low temperature.

A novel catalytic system for benzene oxidation at low temperature is constructed by combining electric field with Pt-Ce-Zr nano-catalyst. The 1 wt% Pt/Ce0.75Zr0.25O2 catalyst assisted by electric field shows the best catalytic performance with 90% benzene conversion at 96.5 °C and excellent water resistance. The effect of electric field on catalysts and catalytic process is comprehensively investigated. The results of XRD, TEM, XPS and H2-TPR reveal that the electric field show negligible influence on the crystal structure and surface morphology of the catalyst, but it can lead to more oxygen vacancies. Therefore, more adsorbed oxygen with higher activity will be produced on the catalyst surface. The redox performance is improved due to the fact that valence distribution of Pt is changed in forms of more active sites composed of high valence oxides (PtO) generated in electric field. In situ DRIFTS is used to investigate the oxidation process of benzene and the results prove that electric field could accelerate the production and consumption of intermediate products, and produce new intermediate products such as carboxylic acid species, indicating that the introduction of electric field may open up a new rapid reaction path and promote the activation of benzene at low temperature.

A relationship between the V4+/V5+ ratio and the surface dispersion, surface acidity, and redox performance of V2O5-WO3/TiO2 SCR catalysts.

A series of V2O5-WO3/TiO2 catalysts with different vanadium loading amounts were prepared by an impregnation method and were characterized by XRD, Raman spectroscopy, XPS, DRIFTS, Py-DRIFTS, NH3-TPD, H2-TPR, etc. The results show that the catalytic activity is related to the ratio of V4+/V5+. The variation of the V4+/V5+ ratio caused by the different dispersion states of vanadia oxide leads to changes in the surface acidity and redox properties of the catalysts. As the V4+/V5+ ratio reaches the maximum value, the apparent activation energy (E a) required to form the transition state on the Brønsted acid sites is the lowest. Artificial regulation of vanadium loading to properly increase V4+/V5+ content may affect the interactions between V, W, O and Ti atoms, which enhances NH3-SCR reaction performance.