Unexpected Promotion
Effect of H<sub>2</sub>O on the
Selective Catalytic Reduction of NO<sub><i>x</i></sub> with
NH<sub>3</sub> over Cu-SSZ-39 Catalysts
Water molecules commonly inhibit the selective catalytic
reduction
(SCR) of NOx with NH3 on most
catalysts, and water resistance is a long-standing challenge for SCR
technology. Herein, by combining experimental measurements and density
functional theory (DFT) calculations, we found that water molecules
do not inhibit and even promote the NOx conversion to some extent over the Cu-SSZ-39 zeolites, a promising
SCR catalyst. Water acting as a ligand on active Cu sites and as a
reactant in the SCR reaction significantly improves the O2 activation performance and reduces the overall energy barrier of
the catalytic cycle. This work unveils the mechanism of the unexpected
promotion effect of water on the NH3–SCR reaction
over Cu-SSZ-39 and provides fundamental insight into the development
of zeolite-based SCR catalysts with excellent activity and water resistance