The effect of alkali metal over Mn/TiO2 for low-temperature SCR of NO with NH3 through DRIFT and DFT

Tailored Alkali Resistance of DeNOx Catalysts by Improving Redox Properties and Activating Adsorbed Reactive Species

“…After K poisoning, the reactivity of NH x and nitrate species largely decreases on SO 4 Nowadays, it is generally believed that the decrease in acidity is the dominant reason for the deactivation of catalysts after alkali poisoning (Hu et al, 2015b;Putluru et al, 2011;Wang et al, 2015). Additionally, the impaired redox properties resulting from alkali poisoning also lead to the decline of activity, such as the reduced reducibility for K-poisoned V 2 O 5 -WO 3 /TiO 2 (Wang et al, 2019) and decreased oxidative capacity for K-poisoned Mn/TiO 2 (Wei et al, 2018). Besides the reduced acidity and redox properties, the absence of active NO x species at low temperatures and the formation of inactive nitrate species at high temperatures result in the decreased activity of alkali-poisoned V 2 O 5 /CeO 2 (Peng et al, 2014).…”

The Effect of Tourmaline on SCR Denitrification Activity of MnOx/TiO2 at Low Temperature

“…However, the previous work of the research group shows that the adsorption energy of the catalyst without electric field is 2.66 and 1.38 eV. [20]. The adsorption energy of NO and NH 3 in the presence of an electric field was higher than that in the absence of electric field, indicating that the amount of adsorption of NO and NH 3 were enhanced by the presence of tourmaline; at the same time, the performance of the catalyst was promoted.…”

Recent progress of low-temperature selective catalytic reduction of NOx with NH3 over manganese oxide-based catalysts

“…133 The ions Na + and K + exhibited more toxic effects than the ions Mg 2+ and Ca 2+ , and the toxic effects of the ions on the catalysts followed the order K + 4 Na + 4 Ca 2+ 4 Mg 2+ , and K + had the most severe toxic effect on the catalyst. 134,135 Wei et al 136 pointed out that the addition of K + would decrease the activity of the catalyst. During the NO adsorption, NH 3(ad) reacts more readily with bridging nitrate or double-dentate nitrate than with monodentate nitrate, whereas doping with K + tends to cause the occupation of the high-energy state and reduces the oxidation capacity, causing NO to adsorb on the catalyst as monodentate nitrate, thus reducing the SCR performance.…”