Mutual inhibition effects on the synchronous conversion of benzene, toluene, and xylene over MnOx 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 MnO2 nanowire. Competitive adsorption of xylene (absorption energy (Eads): -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-1 (benzene), 0.90 min-1 (toluene) and 2.42 min-1 (xylene) for mixed BTX conversion over the MnO2. Doping MnO2 with K+, Na+ and Ca2+ 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-MnO2 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. (c) 2023 Elsevier Inc. All rights reserved.

Automated summary

The synchronous conversion behavior of benzene, toluene, and xylene (BTX) over MnO2 nanowire catalyst was studied. Xylene was found to have competitive adsorption, leading to its preferential conversion and inhibiting the oxidation of toluene and benzene. Doping MnO2 with K+, Na+, and Ca2+ enhanced its ability to oxidize individual VOCs but did not change the conversion mechanism of mixed BTX. K-MnO2 exhibited superior performance with 90% conversion over a long-term operation.