| Summary: | Au, Pt, and Pt-Au catalysts supported on Al<sub>2</sub>O<sub>3</sub> and CeO<sub>2</sub>-Al<sub>2</sub>O<sub>3</sub> were studied in the oxidation of dichloromethane (DCM, CH<sub>2</sub>Cl<sub>2</sub>). 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<sub>2</sub>O<sub>3</sub>-supported and by 35 and 40 degrees with the CeO<sub>2</sub>-Al<sub>2</sub>O<sub>3</sub>-supported catalysts. Excellent HCl selectivities close to 100% were achieved with the Au/Al<sub>2</sub>O<sub>3</sub> and Pt-Au/Al<sub>2</sub>O<sub>3</sub> 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<sub>2</sub>O<sub>3</sub> catalyst was active and durable, but the selectivity towards the total oxidation products needs improvement. The results suggest that, with the Au-containing Al<sub>2</sub>O<sub>3</sub>-supported catalysts, DCM decomposition mainly occurs via direct DCM hydrolysis into formaldehyde and HCl followed by the oxidation of formaldehyde into CO and CO<sub>2</sub>.
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