In situ IR studies of Co and Ce doped Mn/TiO2 catalyst for low-temperature selective catalytic reduction of NO with NH3

Abstract The Mn–Co–Ce/TiO 2 catalyst was prepared by wet co-impregnation method for selective catalytic reduction of NO by NH 3 in the presence of oxygen. The adsorption and co-adsorption of NH 3 , NO and O 2 on catalysts were investigated by in situ FTIR spectroscopy. The results suggested that addition of cobalt and cerium oxides increased the numbers of acid and redox sites. Especially, the cobalt oxide produced lots of Bronsted acid sites, which favor to the adsorption of coordinated NH 3 through NH 3 migration. Ce addition improved amide ions formation to reach best NO reduction selectivity. A mechanistic pathway over Mn–Co–Ce/TiO 2 was proposed. At low-temperature SCR reaction, coordinated NH 3 reacted with NO 2 − , and amide reacted with NO (ad) or NO (g) to form N 2 . NO 2 was related to the formation of nitrite on Co-contained catalysts and the generation of NH 2 − on Ce-contained catalysts. At high temperature, the other branch reaction also occurred between the coordinated NH 3 and nitrate species, resulting in N 2 O yield increase.