Catalytic activity of Pd loaded on WO3/Al2O3 for NO–CH4–O2 in the presence of water vapor

Pd loaded on various kinds of monolayer supports was applied for selective reduction of NO by methane in the presence of O2 and water vapor. Pd/WO3/Al2O3 exhibited the highest conversion of NO to N2 among Pd loaded monolayer supports. The catalyst was relatively tolerant and reversible upon the exposure of water vapor. This is due to the enhanced amount of Brønsted acid sites under the moisture as evidenced by the IR measurement of adsorbed pyridine. The Brønsted acid sites generated on WO3/Al2O3 support were required to give the dispersed Pd species, similar to on the zeolite.