Effect of Ni Addition on Methane Catalytic Combustion Performance of Pd/Al2O3 Catalyst

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 N-2 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 degrees C. 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.