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

Tonglu Lu; Chunxia Zhang; Fangyuan Du; Changsen Zhang; Ruiqin Zhang; Panpan Liu; Juexiu Li

doi:10.1016/j.jcis.2023.03.103

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

J Colloid Interface Sci. 2023 Jul:641:791-802. doi: 10.1016/j.jcis.2023.03.103. Epub 2023 Mar 21.

Authors

Tonglu Lu¹, Chunxia Zhang¹, Fangyuan Du¹, Changsen Zhang¹, Ruiqin Zhang¹, Panpan Liu², Juexiu Li³

Affiliations

¹ School of Ecology & Environment, Zhengzhou University, Zhengzhou 450001, China.
² School of Ecology & Environment, Zhengzhou University, Zhengzhou 450001, China. Electronic address: liupanpan@zzu.edu.cn.
³ College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, China; School of Energy & Environment, Zhongyuan University of Technology, No.41 Zhongyuan Road, Zhengzhou 450007, China.

PMID: 36966568
DOI: 10.1016/j.jcis.2023.03.103

Abstract

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 (E_ads): -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.

Keywords: Alkali (earth) metals; Benzene; Catalytic oxidation; Competitive adsorption; MnO(2); Multiple VOCs; Mutual effects; Practical application; Toluene; Xylene.