SO-Induced Alkali Resistance of FeVO/TiO Catalysts for NO Reduction.

Selective catalytic reduction of nitrogen oxides with ammonia (NH-SCR) is an efficient NO abatement strategy, but deNO catalysts suffer from serious deactivation due to the coexistence of multiple poisoning substances such as K, SO, etc. in the flue gas. It is essential to understand the interaction among various poisons and their effects on NO abatement. Here, we unexpectedly identified the K migration behavior induced by SO over K-poisoned FeVO/TiO catalysts, which led to alkali-poisoning buffering and activity recovery. It has been demonstrated that the K would occupy both redox and acidic sites, which severely reduced the reactivity of FeVO/TiO catalysts. After the sulfuration of the K-poisoned catalyst, SO preferred to be combined with the surface KO, lengthened the K-O and K-O, and thus released the active sites poisoned by KO, thereby preserving an increase in the activity. As a result, for the K-poisoned catalyst, the conversion of NO increased from 21 to 97% at 270 °C after the sulfuration process. This work contributes to the understanding of the specific interaction between alkali metals and SO on deNO catalysts and provides a novel strategy for the adaptive use of one poisoning substance to counter another for practical NO reduction.