Performance, structure and kinetics of Pd catalyst supported in Ba modified γ-Al2O3 for low temperature wet methane oxidation

Low temperature wet methane oxidation is critical for the after-treatment of exhaust from the vehicles powered with natural gas-fueled engine, which is always operated at low temperatures and with high water vapor concentrations. Herein, Pd/Ba-Al2O3 catalysts were prepared, with different amount of Ba as the promoter. It was found that the Pd/Ba-Al2O3 catalysts were superior to the reference Ba-free Pd/Al2O3 catalyst in terms of methane conversion, intrinsic activity and hydrothermal stability. Based on the sufficient characterization results, the location, size, valence state and diverse properties of Pd regulated by Ba were revealed. The benefit from Ba addition on the catalytic performance was demonstrated to be derived from the favorable location of Pd inside the porous channel and the enhancement in the capability for O2 activation. This work can provide insights into the effect of promoters on the catalysts, offer an avenue to designing highly efficient wet methane oxidation catalyst, and lay a foundation for the application of Pd/Ba-Al2O3 in exhaust after-treatment for the natural gas-fueled vehicles.