Oxidation of Dichloromethane over Au, Pt, and Pt-Au Containing Catalysts Supported on γ-Al(2)O(3) and CeO(2)-Al(2)O(3)

Au, Pt, and Pt-Au catalysts supported on Al(2)O(3) and CeO(2)-Al(2)O(3) were studied in the oxidation of dichloromethane (DCM, CH(2)Cl(2)). High DCM oxidation activities and HCl selectivities were seen with all the catalysts. With the addition of Au, remarkably lower light-off temperatures were observed as they were reduced by 70 and 85 degrees with the Al(2)O(3)-supported and by 35 and 40 degrees with the CeO(2)-Al(2)O(3)-supported catalysts. Excellent HCl selectivities close to 100% were achieved with the Au/Al(2)O(3) and Pt-Au/Al(2)O(3) catalysts. The addition of ceria on alumina decreased the total acidity of these catalysts, resulting in lower performance. The 100-h stability test showed that the Pt-Au/Al(2)O(3) catalyst was active and durable, but the selectivity towards the total oxidation products needs improvement. The results suggest that, with the Au-containing Al(2)O(3)-supported catalysts, DCM decomposition mainly occurs via direct DCM hydrolysis into formaldehyde and HCl followed by the oxidation of formaldehyde into CO and CO(2).