Uncovering the Dinuclear Mechanism of NO2-Involved NH3-SCR over Supported V2O5/TiO2 Catalysts.

Abstract

Commercial vanadium oxide catalysts exhibit high efficiency for the selective catalytic reduction (SCR) of NO with NH3, especially in the presence of NO2 (i.e., occurrence of fast NH3-SCR). The high-activity sites and their working principle for the fast NH3-SCR reaction, however, remain elusive. Here, by combining in situ spectroscopy, isotopic labeling experiments, and density functional theory (DFT) calculations, we demonstrate that polymeric vanadyl species act as the main active sites in the fast SCR reaction because the coupling effect of the polymeric structure alters the elementary reaction step and effectively avoids the high energy barrier of the rate-determining step over monomeric vanadyl species. This study unveils the high-activity dinuclear mechanism of the NO2-involved SCR reaction over vanadia-based catalysts and provides a fundamental basis for developing high-efficiency and low V2O5-loading SCR catalysts.