Catalytic combustion of benzene over γ-alumina supported chromium oxide catalysts

Abstract

The γ-alumina supported chromium oxide catalysts with Cr loadings varying from 1.7 to 13.6wt.% were prepared by the impregnation method and characterized using N2 adsorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and Raman spectroscopy. Benzene combustion catalyzed by the catalysts was investigated. The results showed that chromia was well dispersed on the surface of γ-Al2O3 with a monolayer dispersion capacity of 7.5wt.%. For the supported chromia catalyst with a Cr loading of 1.7wt.%, only Cr6+ species were observed. Increasing Cr loading to 5.1wt.% led to the presence of both Cr3+ and Cr6+ species. Catalytic benzene combustion over the catalysts was found to be strongly dependent on Cr loading amount. For supported chromia catalyst with a Cr loading of 8.5wt.%, complete benzene combustion was achieved at 350°C which was substantially lower than the temperature for other catalysts, indicating that supported chromia catalyst at a near monolayer dispersion capacity exhibited the optimum catalytic behavior for benzene combustion.