Boosting SO2-Tolerant Catalytic Reduction of NOx via Selective Adsorption and Activation of Reactants over Ce4+–SO42– Pair Sites

Developing highly SO 2 -tolerant catalysts at low and moderate temperatures remains a crucial bottleneck in selective catalytic reduction (SCR) of NO x by NH 3 . Herein, SO 2 -tolerant SCR of NO x is boosted via selective adsorption and activation of reactants over Ce 4+ –SO 4 2– pair sites on CeO 2 catalysts by sulfur doping. Interestingly, a sulfur dopant, characterized as bulk sulfate bidentate coordinating over (sub)surface of CeO 2 catalysts, utilizes strong electronegativity to induce the neighboring Ce atoms to be charge-deficient. This electronic effect simultaneously weakens the electronic interaction between CeO 2 and SO 2 as well as alleviates the oxidation capacity of CeO 2 catalysts, resulting in the suppression of adsorption and oxidation of SO 2 . Meanwhile, the oxidation of NO is also alleviated to generate SCR reactive NO 2 /nitrite species accompanied by increased Brønsted acid sites over Ce 4+ –SO 4 2– pair sites. This work deepens the understanding of the SO 2 -tolerant SCR mechanism and provides an efficient strategy for further designing highly efficient SO 2 -tolerant SCR catalysts.