Relationship between the WO3 states and reaction pathway over CeO2-ZrO2-WO3 catalysts for selective catalytic reduction of NO with NH3

The CeO 2 -ZrO 2 -WO 3 catalysts were investigated for the selective catalytic reduction of NO x by NH 3 (NH 3 -SCR). The results indicated that monodentate nitrate species generated from amorphous WO 3 , and these species could not be observed over CeO 2 -ZrO 2 -WO 3 with the presence of Ce 2 (WO 4 ) 3 compounds. The formation of amorphous W species resulted in the abundant of Ce 3+ and oxygen vacancies. Besides, the amorphous W species could enhance the surface acidity and NO oxidation ability. Nitrate species (bridging nitrate and monodentate nitrate), coordinated NH 3 and NH 4 + all participated in the NH 3 -SCR process. The NH 3 -SCR reaction pathway of CeO 2 -ZrO 2 -WO 3 mainly followed Langmuir-Hinshelwood mechanism.