Enhanced hydrothermal stability of high performance lean fuel combustion alumina-supported palladium catalyst modified by nickel

The hydrothermal stability of Pd-based methane combustion catalyst was investigated under lean-fuel conditions, such as ventilation air methane. For the catalyst, the active component Pd was impregnated on Ni-modified alumina supports which were prepared by a modified method. The method was coupled with the conventional co-precipitation and hydrothermal synthesis process. A series of Pd catalysts and supports prepared, which had the Ni/Al ratios of 1:4, 1:2 and 1:1, were characterized by BET, CO-chemisorption, XRD, TPR, SEM and TEM. The relationship between active sites and supports was studied using HRTEM. In addition, the performances for lean methane combustion of all catalysts were studied. Results showed that the catalyst on well crystallized NiAl2O4 spinel support exhibited the superior hydrothermal stability. Methane conversion remained 96% after 3200 h at 873 K. Such excellent catalytic performance has been validated to relate to the stabilizing effect of support and the least lattice mismatch between NiAl2O4 and Pd, which contributed to high Pd dispersion.

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► Pd/Al2O3 catalyst modified by nickel for methane combustion under lean-fuel condition.
► Catalyst on NiAl2O4 support demonstrates the most excellent hydrothermal stability.
► The methane conversion of Pd/NiAl2O4 was still about 96% at 823 K after 3200 h test.
► The least lattice mismatch between Pd and NiAl2O4 leads to high Pd dispersion.
► Pd/NiAl2O4 catalyst is an appropriate candidate for lean fuel methane combustion.