1,2-Dichloroethane Deep Oxidation over Bifunctional Ru/CexAly Catalysts

Abstract

Ru/CexAly catalysts were synthesized with impregnation of RuCl3 aqueous solution on CexAly (Al2O3-CeO2) and used in 1,2-dichloroethane (1,2-DCE) oxidation. Characterization by X-ray diffraction, Raman, NH3-temperature-programmed desorption (TPD), CO2-TPD, X-ray photoelectron spectroscopy, and H2-temperature-programmed reduction indicates that CeO2 exists as a form of face-centered cubic fluorite structure, whereas the chemical states and the structure of Ru species are dependent on the Ce content. The reducibility and acidity of catalysts increase with Ce/Ce + Al ratio. However, the latter is promoted only in a Ce/Ce + Al range of 0-0.25 and then decreases quickly. Ru/CexAly catalysts have considerable activity for 1,2-DCE combustion. TOFRu of 1,2-DCE oxidation increases with strong acid, which is ascribed to a synergy of reducibility and acidity. Ru greatly inhibits the chlorination through the decreases in both Cl deposition and CH2=CHCl formation. High stability of Ru/Ce10Al90 maintains at 280 °C for at least 25 h with CO2 selectivity of 99% or higher. In situ Fourier transform infrared spectroscopy indicates that 1,2-DCE dissociates to form ClCH2-CH2O- species, which is an intermediate species for the production of CH3CHO and CH2=CHCl, the former responsible for deep oxidation.