Catalytic activity of oxide-supported Pd catalysts on a honeycomb for low-temperature methane oxidation

Low-temperature methane oxidation over oxide-supported Pd catalysts coated on a metal or ceramic honeycomb was investigated for gas turbine applications. Al₂O₃ and SnO₂ were used as washcoat material, and a Fe-Cr-Al alloy and cordierite were adopted as metal and ceramic honeycombs, respectively. Pd catalysts on the honeycomb were prepared by varying washcoat loading and washcoat calcination temperature. It was found that the catalytic activities of Pd/SnO₂ on metal and ceramic honeycombs improved with increasing washcoat loading and precalcination temperature of the washcoat material. Especially, significant enhancement of the catalytic activity appeared for Pd/SnO₂/ceramic honeycomb as the washcoat loading increased from 150 to 200g/l. The catalytic activity of the honeycomb catalysts was examined under high pressure and space velocity. The temperature at which the increase in CH₄ conversion became noticeable was shifted to higher temperature compared to the experiments at lower space velocity and ambient pressure. CH₄ conversion over the honeycomb catalysts fluctuated as the catalyst bed inlet temperature was raised. Pd/SnO₂/ceramic honeycomb exhibited the highest stable activity for low-temperature methane oxidation.