Novel mechanistic view of catalytic ozonation of gaseous toluene by dual-site kinetic modelling

Hu, Maocong, Yao, Zhenhua, Hui, K.N. and Hui, K.S. (2017) Novel mechanistic view of catalytic ozonation of gaseous toluene by dual-site kinetic modelling. Chemical Engineering Journal, 308. 710–718. ISSN 1385-8947

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    Abstract

    The catalytic ozonation of VOCs is a promising approach for degradation of indoor VOCs, such as gaseous toluene. However, the mechanism and relevant kinetic steps involved in this reaction remain unclear. In this study, the catalytic ozonation of toluene over MnO2/graphene was investigated using the empirical power law model and classic Langmuir-Hinshelwood single-site (denoted as L-Hs) mechanism. The apparent activation energy determined using the power law model was 29.3±2.5 kJ mol−1. This finding indicated that the catalytic ozonation of toluene over MnO2/graphene was a heterogeneous reaction, and the Langmuir-Hinshelwood mechanism was applicable. However, the L-Hs mechanism did not fit the experimental data, suggesting that the reaction was non-single-site governed. A novel Langmuir-Hinshelwood dual-site (denoted as L-Hd) mechanism was then proposed to explain the experimental observations of the catalytic ozonation of toluene over MnO2/graphene through a steady-state kinetic study. This mechanism was based on the hypothesis that MnO2 was responsible for ozone decomposition and toluene adsorption on graphene; these two types of adsorption were coupled by an adjacent attack. Furthermore, XPS results confirmed the presence of a strong connection between MnO2 and graphene sites on the surface of MnO2/graphene. This connection allowed the adjacent attack and validated the dual-site mechanism. The L-Hd model was consistent with the predicted reaction rate of toluene removal with a correlation coefficient near unity (r2 = 0.9165). Moreover, the physical criterion was in accordance with both enthalpy and entropy of toluene adsorption constraints. Fulfillment of mathematical and physical criteria indicated the catalytic ozonation of toluene over MnO2/graphene can be well described by the L-Hd mechanism. This study helps understand the catalytic ozonation of toluene over MnO2/graphene in a closely mechanistic view.

    Item Type: Article
    Uncontrolled Keywords: graphene,toluene degradation,catalytic ozonation,langmuir-hinshelwood dual-site mechanism,kinetic modelling
    Faculty \ School: Faculty of Science > School of Mathematics
    Depositing User: Pure Connector
    Date Deposited: 26 Sep 2016 16:00
    Last Modified: 09 Apr 2019 11:33
    URI: https://ueaeprints.uea.ac.uk/id/eprint/60589
    DOI: 10.1016/j.cej.2016.09.086

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