Active sites and redox properties of supported palladium catalysts for nitric oxide direct decomposition

Abstract Surface properties of supported palladium catalysts for NO decomposition were characterized using hydrogen adsorption, X-ray photoelectron spectroscopy (XPS), and temperature-programmed desorption and oxidation (TPD and IPO). Conversion of NO on Pd/MgO was proportional to the surface area of palladium. The interaction between palladium species and Mg 2+ ions plays an important role in forming active sites for NO decomposition. Reduced palladium on MgO was not readily oxidized to PdO by oxygen even at high temperatures, in contrast to its behavior on SiO 2 . Oxygen adsorbed on reduced Pd/MgO desorbed at temperatures lower than those for bulk PdO/ MgO. It was concluded that NO decomposition on Pd/MgO catalysts proceeds mainly by a redox mechanism on partially reduced palladium species interacting with Mg 2+