Enhancement of activity and hydrothermal stability of Pd/ZrO2-Al2O3 doped by Mg for methane combustion under lean conditions

By a facile doping strategy, a new Pd catalyst supported on ZrO2-Al2O3 composite doped by Mg was developed. The catalyst was carefully characterized by X-ray diffraction (XRD), CO chemical adsorption, transmission electron microscope (TEM), NH3 temperature programmed desorption (NH3-TPD) and X-ray photoelectron spectroscopy (XPS). The results revealed that the physical and chemical properties of the catalyst can be modulated by Mg dopant. An MgAl2O4 spinel was formed by Mg doping, which can stabilize Pd2+ species and inhibit the formation of hydroxyl groups on the surface of support. Compared with its analogous catalyst without Mg dopant, the Mg-doped catalyst had higher Pd dispersion and smaller Pd nanoparticles. Moreover, a more suitable acidity for methane oxidation can be generated on the surface of the catalyst upon Mg doping. Therefore, the introduction of Mg doping strongly enhanced the low temperature activity and hydrothermal resistance of the catalyst for the total oxidation of methane under lean conditions. Notably, the complete conversion temperature of methane can decreased significantly by 40-50 degrees C with the doped catalyst before and after harsh hydrothermal aging treatment. (C) 2016 Published by Elsevier Ltd.