Durable and, selective activity of Pd loaded on WO3/ZrO2 for NO-CH4-O2 in the presence of water vapor

Pd loaded on WO3/ZrO2 was applied for the selective reduction of NO by methane in the presence Of O-2. The catalyst exhibited the highest NO and methane conversion when WO3 monolayer covered over ZrO2 surface. NO reduction activity was observed when I'd loading was lower than 0.17 wt.%. However, further increase in the Pd concentration lowered the NO conversion due to the occurrence of direct oxidation of methane. The I'd loaded on monolayer-WO3/ZrO2 catalyst exhibited durable and selective activity for the NO-CH4-O-2 reaction. The selectivity was considerably improved in an atmosphere of 10% water vapor. The durability of the catalysis was responsible for the stability and enhanced concentration of Bronsted acidity in WO3/ZrO2 as proved by NH3 temperature programmed desorption TPD and measurement of adsorbed pyridine. (C) 2002 Elsevier Science B.V. All rights reserved.