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 spinet 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. (C) 2012 Elsevier B.V. All rights reserved.