Design strategy for enhancing sulfur resistance in efficient NH3-SCR through confined CeO2 nanoparticles within mesoporous zeolite ZSM-5: Inhibition of SO2 adsorption and reaction

The Ce-based catalysts show promising activity in the selective reduction of NO x with NH 3 (NH 3 -SCR) at medium and low temperatures, yet their limited sulfur tolerance hinders broader application. We have developed a catalyst by confining CeO 2 within the mesopores of ZSM-5 zeolite (CeO 2 @ZSM-5), resulting in uniform dispersion and ultra-small CeO 2 nanoparticles (<10 nm). This distinctive structure enhances the interaction between the carrier and active species, reducing the catalyst's surface basicity and its affinity for acidic SO 2 gas. Additionally, the small CeO 2 particle size leads to an increased Ce 3+ concentration, which inhibits the reaction between Ce active sites and SO 2 . Employing a dual strategy of reducing adsorption and inhibiting reactions, we significantly minimized the impact of SO 2 on NH 3 -SCR. Impressively, common Ce-based catalysts become deactivated due to the formation of corresponding sulfates through reaction with SO 2 , however, CeO 2 @ZSM-5 achieves NO x conversion above 98% and N 2 selectivity of 100% within the temperature range of 250 °C to 450 °C. The addition of 100 ppm SO 2 does not significantly affect NH 3 -SCR activity. This study provides an effective approach to mitigate SO 2 adsorption and reactions, offering a valuable strategy for the development of highly efficient sulfur-resistant catalysts.