Alkali-Resistant NOx Reduction over SCR Catalysts via Boosting NH3 Adsorption Rates by In Situ Constructing the Sacrificed Sites

Abstract

Currently, improving the alkali resistance of vanadium-based catalysts still remains as an intractable issue for the selective catalytic reduction of NO_x with NH₃ (NH₃–SCR). It is generally believed that the decrease in adsorbed NH_x species deriving from the declined acidic sites is the chief culprit for the deactivation of alkali-poisoned catalysts. Herein, alkali-resistant NO_x reduction over SCR catalysts via boosting NH₃ adsorption rates was originally demonstrated by in situ constructing the sacrificed sites. It is interesting that the adsorbed NH_x species largely decrease while the NH₃ adsorption rate is well kept over the V₂O₅/CeO₂ catalyst by in situ constructing the sacrificed sites. The SCR activity could be maintained after alkali poisoning because in situ constructed SO₄^2– groups would prefer to be combined with K⁺ so that the specific V═O species can endow K-poisoned V₂O₅/CeO₂ with high adsorption rate of NH₃ and high reactivity of NH_x species. This work provides a new viewpoint that NH₃ adsorption rate plays more decisive roles in the performance of alkali-poisoned catalysts than the amount of NH₃ adsorption and enlightens an alternative strategy to improve the alkali-resistance of catalysts, which is significant to both the academic and industrial fields.