Catalytic Combustion of Vinyl Chloride Emission over CeO2-MnOx Catalyst

CeO2-MnOx catalyst samples with different Mn/(Ce+Mn) molar ratios (0, 1/4, 1/2, 3/4, and 1) prepared by the citric acid (CA) sol-gel method were studied for catalytic combustion of vinyl chloride (VC) emission. The effects of preparation conditions and operation parameters on the catalytic performance of CeO2-MnOx., were investigated. The catalyst samples were characterized by N-2 adsorption, X-ray diffraction (XRD), and H-2 temperature-programmed reduction (H-2-TPR). In the catalytic combustion of VC over CeO2-MnOx, the products containing HCl, CO2, and H2O were produced and there were no byproducts such as chlorohydrocarbons and chlorine. The CeO2-MnOx catalyst with the molar ratio of CA:Mn:Ce = 0.30:0.50:0.50 showed the best catalytic performance and had better operating flexibility over the ranges of gas hourly space velocity (GHSV) of 10000-30000 h(-1) and VC concentration of 0.05%-0.15%. The temperatures at 50% conversion (110 degrees C) and at 99% conversion (220 degrees C) were achieved at VC concentration of 0.1% and GHSV of 15000 h(-1). XRD characterization indicated that only the characteristic diffraction peaks of CeO2 with the cubic fluorite structure appeared and no characteristic diffraction peaks of MnOx species appeared over CeO2-MnOx catalyst. XRD and H-2-TPR results indicated that Mn ions were incorporated into the CeO2 lattice to form Ce-Mn-O solid solution, which was favorable for improving the reactivity of active oxygen species on the catalyst surface and thereby enhanced the catalyst activity.