Abstract:  Pd/Al₂O₃ catalyst samples modified by Ni promoter were prepared and tested for methane catalytic combustion under lean-fuel condition. A series of Pd catalyst samples with different Ni contents were characterized by N₂ adsorption, X-ray diffraction, temperature-programmed reduction, temperature-programmed desorption of ammonia and transmission electron microscopy. In addition, the performance of the catalyst samples for lean methane combustion was studied. The results showed that the addition of Ni effectively improved the activity and hydrothermal stability of catalyst samples due to the formation of NiAl₂O₄ spinel. As Ni content increased, the NiAl₂O₄ content increased, thus the performance of the catalyst increased. For Pd/Ni-Al₂O₃ sample with 20% Ni, methane conversion remained 97.5% after 150 h at 600 ^oC. Weaker acidity of the supports and the well dispersion of Pd particles on the supports contributed by NiAl₂O₄ phase might be the reason of high performance of the catalyst.

Key words: palladium, alumina, nickel, methane, catalytic combustion