SO 2 -Induced Alkali Resistance of FeVO 4 /TiO 2 Catalysts for NO x Reduction.

Selective catalytic reduction of nitrogen oxides with ammonia (NH 3 -SCR) is an efficient NO x abatement strategy, but deNO x catalysts suffer from serious deactivation due to the coexistence of multiple poisoning substances such as K, SO 2 , etc. in the flue gas. It is essential to understand the interaction among various poisons and their effects on NO x abatement. Here, we unexpectedly identified the K migration behavior induced by SO 2 over K-poisoned FeVO 4 /TiO 2 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 4 /TiO 2 catalysts. After the sulfuration of the K-poisoned catalyst, SO 2 preferred to be combined with the surface K 2 O, lengthened the K-O Fe and K-O V , and thus released the active sites poisoned by K 2 O, thereby preserving an increase in the activity. As a result, for the K-poisoned catalyst, the conversion of NO x 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 2 on deNO x catalysts and provides a novel strategy for the adaptive use of one poisoning substance to counter another for practical NO x reduction.