Construction of cerium-based highly sulfur-resistant catalysts and NH₃-SCR reactions

A core–shell catalyst with ZSM-5 as the core and CeO₂ as the shell was developed to address the poor sulfur tolerance of conventional Cu-based molecular sieve catalysts. The CeO₂ shell was deposited onto the ZSM-5 surface using a wet chemical method. Active Cu species were then introduced via liquid-phase ion exchange, yielding the Cu/(ZSM-5@CeO₂) core–shell catalyst. A genetic algorithm (GA) was applied to systematically optimize the catalyst composition. The optimal configuration was identified at a Cu loading of 2.92 wt% and a CeO₂/ZSM-5 mass ratio of 0.13. Experimental results showed that the optimized catalyst exhibits excellent low-temperature performance in the NH₃-SCR reaction. Nearly 100% NO conversion was achieved over the temperature range of 225–500 °C, while N₂ selectivity remained above 95%. X-ray photoelectron spectroscopy (XPS) analysis revealed that the CeO₂ shell functioned as a sacrificial layer. It preferentially reacts with SO₂ to form surface sulfates, thereby preventing SO₂ from reaching the internal Cu active sites. This mechanism protects the core acidic sites and redox centers. Overall, the core–shell architecture significantly enhances sulfur resistance and promotes reactant adsorption and activation through shell-induced electronic effects. These findings offer new insights into the design of industrial flue-gas denitration catalysts. • A Cu/(ZSM-5@CeO₂) core–shell catalyst was constructed with ZSM-5 as the core and CeO₂ as the shell. • Genetic algorithm optimization identified an optimal Cu loading of 2.92 wt% and a shell mass ratio of 0.13. • The CeO₂ shell significantly enhanced sulfur resistance through a sacrificial mechanism and physical shielding. • Synergistic effects at the core–shell interface promoted low-temperature redox cycling and high N₂ selectivity.