Mutual inhibition effects on the synchronous conversion of benzene, toluene, and xylene over MnO catalysts.

Advancing the practical application of catalytic oxidation technology demands for illustrating the synchronous conversion behavior of various volatile organic compounds (VOCs) over catalysts. Here, the mutual effects of benzene, toluene and xylene (BTX) were examined for their synchronous conversion on the surface of the MnO nanowire. Competitive adsorption of xylene (absorption energy (E): -0.889 eV) facilitated its prior conversion and impeded the oxidization of toluene and benzene over the catalyst. The turnover frequencies were 0.52 min (benzene), 0.90 min (toluene) and 2.42 min (xylene) for mixed BTX conversion over the MnO. Doping MnO with K, Na and Ca could enhance its ability to oxidize the individual VOCs but did not alter the conversion mechanism of mixed BTX over the catalyst. When reducing the competitive effects in the adsorption of BTX, the oxidation performance of catalysts would depend on their ability to oxidize toluene and benzene. K-MnO showed superior properties, i.e. specific surface area, highly low-valent Mn species, high lattice oxygen content, and abundant oxygen vacancy, and then exhibited superior performance during long-term operation (90% conversion in 800 min). The present study uncovered the co-conversion mechanism of multiple VOCs and significantly leveraged the catalytic oxidization technology for VOCs removal in practical application.