Abstract: Pd catalysts supported on mesoporous alumina (M-Al₂O₃) were prepared by an impregnation method and tested for CH₄ catalytic combustion. PdO/M-Al₂O₃ was more active than the PdO catalyst supported on conventional Al₂O₃ because of a higher dispersion of PdO species induced by the mesoporous structure of M-Al₂O₃. Moreover, with increasing calcination temperature, the conversion of CH₄ over PdO/M-Al₂O₃ catalysts first increased and then decreased. The best catalytic performance was obtained on the PdO/M-Al₂O₃ catalyst calcined at 700 ^oC, with a CH₄ conversion of 91% at 400 ^oC. Pd species were mainly in mesoporous channels of the support in the form of highly dispersed PdO particles. When calcined at higher temperature, Pd species were in forms of crystalline Pd and PdO. A decline of reactivity and a higher turnover frequency were obtained on the PdO/M-Al₂O₃ catalyst calcined at 900 ^oC, which might be due to the co-existence of metallic Pd and PdO in the catalyst.

Key words: mesoporous alumina, palladium, methane, catalytic combustion, active site