Mechanism of Low‐Temperature Carbon Combustion Over Ag‐Pd/Alumina Catalysts

The mechanism of carbon combustion over Ag−Pd/alumina catalysts has been studied with the aim of further improving the performance of Ag‐based diesel particulate filter catalysts. Alumina‐supported Ag−Pd, Ag, and Pd catalysts were prepared and compared for their carbon combustion ability. Over the Ag−Pd, Ag, and Pd catalysts, peaks of CO 2 emission were observed at 425, 510, and 650 °C, respectively. Details of the catalyst structure and carbon oxidation process were investigated using energy dispersive X‐ray (EDX) mapping and temperature‐dependent Ag and Pd K ‐edge X‐ray absorption fine structure analysis during carbon combustion. The EDX mapping and extended X‐ray absorption fine structure analyses suggested that Ag−Pd and PdO particles stacked together in the Ag−Pd/alumina catalyst. With this structure, oxygen atoms could migrate effectively to the Ag−Pd particles from the PdO surfaces, allowing low‐temperature combustion over the Ag−Pd/alumina catalyst.