Cl-Resistant Synergistic Removal of NO_xand Chlorobenzene over SmMn₂O₅-Zeolite Composite Catalysts

Synergistic catalytic removal (SyCR) of NO_xand chlorinated volatile organic compound (CVOCs) emission from nonelectric industries is effective to suppress PM_2.5and ozone complex air pollution. Catalysts with balanced competence to reduce NO_xand oxidize CVOCs, as well as the resistance to chlorine poisoning, are critical to SyCR. Here, neighboring effects over SmMn₂O₅mullite (SMO) modified by HZSM-5 composite catalysts (SMO-Z) were demonstrated in the Cl-resistant SyCR of NO_xand chlorobenzene (CB, a representative CVOCs). Characterizations demonstrated that HZSM-5 modification did not alter the crystal structure of SMO and retained Mn–O–Mn–Mn active sites for the SyCR of NO_xand CB. HZSM-5 regulated the redox ability of SMO-Z to reduce the formation of inert nitrate species and to promote the N₂selectivity. Acidic HZSM-5 acted as dechlorination sites to promote the breakage of the C–Cl bond via the nucleophilic substitution reaction and accelerated the formation of HCl to avoid Cl poisoning on catalysts. The fine-tuned compensation of surface acidity by HZSM-5 suppressed the competitive adsorption of NH₃and CB on SMO-Z, which promoted NO_xreduction at high temperatures, whereupon neighboring effects between HZSM-5 acidic dechlorination sites and SMO active redox sites on SMO-Z capitally promoted the SyCR efficiency and antichlorination poisoning performance.