Mechanistic study of better K-resistance on Mn/TiO2 catalysts with preferentially exposed anatase {0 0 1} facets in low-temperature NH3-SCR.

[Display omitted] • Mn/TiO 2 {0 0 1} exhibited better low-temperature NO conversion and K resistance. • K did not decrease the specific surface area of Mn/TiO 2 {0 0 1}. • K had a greater effect on NO adsorption and activation and was more likely to affect the L-H mechanism. The presence of alkali metals in the flue gas can physically and chemically poison the catalyst, leading to catalyst deactivation. In this paper, Mn/TiO 2 catalysts with exposed TiO 2 {0 0 1} (NS) and TiO 2 {1 0 1} (NP) facets are studied for potassium poisoning. It was found that Mn/TiO 2 -NS exhibited higher denitrification efficiency and tolerance to potassium compared to Mn/TiO 2 -NP. Experimental characterizations and DFT calculations showed that the NH 3 -SCR reaction on the surface of both fresh Mn/TiO 2 -NS and Mn/TiO 2 -NP catalysts was controlled by the E-R and L-H mechanisms. The presence of K species did not decrease the specific surface area of Mn/TiO 2 -NS catalyst. Under the same K poisoning condition, Mn/TiO 2 -NS was able to retain more surface acidic sites and surface active species, whose reaction was still controlled by the E-R and L-H mechanisms. While the adsorption and activation of NO on the Mn/TiO 2 -NP surface was severely inhibited by the presence of K, resulting in the L-H mechanism blocked. [ABSTRACT FROM AUTHOR]