Dispersion of palladium on alumina surfaces

Abstract

Catalytic burners for gas turbine power generation are nearing commercialization in engines with moderate inlet temperatures (< 1,600 K). Catalytic combustion of natural gas provides ultra low emissions with nitrogen oxides (NO[sub x]) levels below 1 ppm in the exhaust. The catalyst developed for these burners contain palladium oxide (PdO) dispersed over the surfaces of stabilized alumina supports. The catalyst operates at temperatures near the decomposition point of PdO, where the rate of combustion becomes nearly independent of temperature. The durability of the PdO catalyst requires a highly stable supporting oxide. It also depends on nucleation growth, and fragmentation of oxide films on palladium crystallites and on redispersing forces at PdO/alumina interfaces to counter sintering of PdO and Pd particles. In this work, the authors have used reproducible temperature and time transient kinetics of methane oxidation by PdO supported on sintered lanthanum hexaaluminate to provide information about the dispersion of PdO in the complex PdO/Pd/aluminate catalyst system.