Pd-LaMnO3 as dual-site catalysts for methane combustion

Dual site Pd-LaMnO3 monolithic catalysts with different Pd loadings were prepared and tested in the high temperature lean premixed combustion of methane. It was shown that the novel catalysts effectively combine low and high temperature oxidation activity within a single system, which in turn has a wider operating window than Pd or LaMnO3 alone. In particular, evidence was found of a self-regenerative thermal activation process which restores Pd sites responsible for light-off at low temperature. Morphological and chemical analysis (SEM-EDS, BET, ICP-MS, XPS) of Pd-LaMnO3 catalysts were correlated to the results of extensive isothermal and self-sustained (steady state and transient) combustion tests in order to shed light on the nature of the catalytic species acting at different temperature levels, and on the reversible synergic interactions occurring between Pd and perovskite upon controlled thermal treatments or reaction ageing.