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

The CeO2-ZrO2-WO3 catalysts were investigated for the selective catalytic reduction of NOx by NH3 (NH3SCR). The results indicated that monodentate nitrate species generated from amorphous WO3, and these species could not be observed over CeO2-ZrO2-WO3 with the presence of Ce-2(WO4)(3) compounds. The formation of amorphous W species resulted in the abundant of Ce3+ 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 NH3 and NH4+ all participated in the NH3-SCR process. The NH3-SCR reaction pathway of CeO2-ZrO2-WO3 mainly followed Langmuir-Hinshelwood mechanism. (C) 2017 Elsevier B.V. All rights reserved.