BaSO₄-Coated V/Fe/Barium Slag ZSM-5 Catalysts for Improved SO₂ Tolerance in SCR: Insights into a Dual-Protection...

Hazardous solid waste [e.g., barium slag (BS)] can be transformed into highly efficient molecular sieve catalysts. However, catalyst deactivation caused by SO₂ poisoning remains a critical scientific challenge that requires urgent attention. Herein, V/Fe/BS-ZSM-5 molecular sieves have been devised for the NH₃-SCR for NO removal reaction, showing improved SO₂ resistance. This protection includes a two-step protection process: first, Ba²⁺ acts as a sacrificial agent by reacting with SO₂, and subsequently, the resulting BaSO₄ layer serves as a physical barrier. A range of advanced characterization methods (e.g., H₂-TPR, NH₃-TPD, TG, and in situ DRIFTS spectroscopy) were employed to gain a more comprehensive understanding of the catalyst's resistance to sulfur poisoning and its underlying reduction mechanism. The results demonstrate that the VFBZx catalysts possess remarkable resistance to SO₂ and maintain stable catalytic performance, which can be ascribed to a dual-protection mechanism. The incorporation of Ba²⁺ significantly inhibits how SO₂ moves through the catalyst, thus restricting sulfation to the catalyst layers. Subsequently, the BaSO₄ coating acts as an additional protective barrier on the catalyst surface, suppressing SO₂ adsorption and preventing the active metal sites (V⁵⁺-O_v-Fe³⁺ interfacial sites) from being poisoned. This material is expected to effectively convert BS into high-value zeolite materials through a simple synthesis method, showing promising commercial potential.