Post‐Plasma Catalytic Degradation of Toluene over OMS‐2/NiMn‐LDHs Composite: Performance and Mechanism

Addressing the issue of inefficient synergy between nonthermal plasma technology and catalysts, this study integrates NiMn‐LDHs with octahedral molecular sieve (OMS‐2) to develop a novel, high‐efficiency catalyst for toluene degradation in combination with dielectric barrier discharge (DBD) plasma. A series of NiMn‐LDHs catalysts by varying Ni/Mn molar ratios were synthesized and evaluated for their synergistic performance with post‐plasma catalytic (PPC) system for toluene degradation. Synthesized catalysts present excellent crystallinity and characteristic layered structure. Experimental results demonstrated that the DBD‐catalytic system significantly enhanced the toluene conversion, CO 2 selectivity, and carbon balance, compared to DBD alone, while effectively suppressing the formation of byproducts such as O 3 and NO x . Among these, Ni 3 Mn 1 ‐LDHs (molar ratio of Ni/Mn = 3:1) exhibited superior synergistic catalytic performance with DBD plasma. Subsequently, highly active OMS‐2 was loaded onto Ni 3 Mn 1 ‐LDHs, and its synergistic catalytic degradation of toluene with DBD plasma was investigated. OMS‐2 1 /NiMn‐LDHs 1 exhibits the highest catalytic activity of 95.2% and CO 2 selectivity of 60% at SED of 718.44 J L −1 , leading to 35.5% and 45% enhancements compared to DBD alone. The possible degradation mechanism of toluene in PPC hybrid system was proposed via XPS analysis and GC‐MS. The results revealed that DBD plasma generates abundant radicals and active species to decompose toluene, while the unreacted toluene and intermediates in the gas phase adsorb onto the catalyst surface. These adsorbed species react with hydroxyl groups on the LDHs and multivalence Mn and lattice oxygen in OMS‐2, further promoting the toluene degradation. Additionally, the various oxidation states of Mn can activate O 3 to promote the generation of reactive oxygen species, further facilitating toluene and intermediates to mineralize into harmless CO 2 and H 2 O.