Oxidation of Dichloromethane over Au, Pt, and Pt-Au Containing Catalysts Supported on γ-AlO and CeO-AlO

Au, Pt, and Pt-Au catalysts supported on AlO and CeO-AlO were studied in the oxidation of dichloromethane (DCM, CHCl). 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 AlO-supported and by 35 and 40 degrees with the CeO-AlO-supported catalysts. Excellent HCl selectivities close to 100% were achieved with the Au/AlO and Pt-Au/AlO 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/AlO catalyst was active and durable, but the selectivity towards the total oxidation products needs improvement. The results suggest that, with the Au-containing AlO-supported catalysts, DCM decomposition mainly occurs via direct DCM hydrolysis into formaldehyde and HCl followed by the oxidation of formaldehyde into CO and CO.