Ru-Promoted CrOx/Al2O3 Catalyst for the Low-Temperature Oxidative Decomposition of Trichloroethylene in Air

Abstract

A series of Ru-promoted CrOx/Al2O3 as catalysts for the low-temperature oxidative decomposition of trichloroethylene (TCE) were characterized and evaluated in comparison with an unpromoted CrOx/Al2O3 catalyst. Catalyst characterization was conducted by surface area measurement, X-ray diffraction and X-ray photoelectron spectroscopy. Catalyst performance in the TCE decomposition reaction was evaluated with respect to the initial catalytic activity, the rate of catalyst deactivation, and the product concentrations of CO and Cl2 under dry or wet air conditions. The presence of a small amount of Ru, as much as 0.4 wt% in a CrOx/Al2O3 catalyst, brought about several beneficial effects on the catalytic reaction performance. As compared with the unpromoted CrOx/Al2O3, this Ru-promoted CrOx/Al2O3 catalyst showed enhanced catalytic activity (249 versus 264 °C in terms of temperature at which 50% of TCE conversion occurred), a reduced concentration of CO (180 versus 325 ppm) in the product, and a decreased propensity to deactivation. Performance improvements of the Ru-promoted CrOx/Al2O3 catalyst were thought to originate from its enhanced oxidation activity due to the coexisting highly-dispersed Ru oxides rendering less active Cr(III) to more active Cr(VI), and facilitating the process of supplying activated oxygen for the reaction system.