The Reaction of Poisonous Alkali Oxides with Vanadia SCR Catalyst and the Afterward Influence: A DFT and Experimental Study

Abstract

Brønsted acid sites and reducibility are crucial for a vandaia catalyst in selective catalytic reduction of NO reaction. Alkali oxides are poisonous to vanadia catalyst. Theoretical chemistry computations and experiments were performed to study the reaction of alkali oxides with the catalyst and the afterward influence left on the catalyst. Both NH3 adsorption and neutralization by alkali oxides proceed on Brønsted acid sites. Theoretical computation with density functional theory shows that neutralization by alkali oxide is more exothermic than NH3 adsorption. The easy consumption of Brønsted acid sites by alkali oxides results in the transformation of surface nature and the decrease of acidity, which is experimentally testified by the NH3 sorption results. The replacement of hydrogen ion by the alkali ion after neutralization will cause the reduction of vanadium atom, as indicated by computed Mulliken charges. This has led to the lower reducibility of the catalyst, which is verified by the theoretical hydrogenation process and experimental hydrogen reduction profile.