Formation of polycyclic aromatic hydrocarbons, benzofuran, and dibenzofuran in fuel-rich oxidation of toluene using a flow reactor

Abstract

Recently, polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (OPAHs) have been attracting considerable attention owing to their high toxicity. Understanding their formation mechanism during combustion processes is important to control...

Thermochemical and kinetic studies of H-abstraction reaction of benzofurans and benzodioxins by H-atoms

“…S17 in the Supplementary Materials. These results reveal that the studied OPAHs (BZF and DBZF) start to form at ~800 K with a peak mole fraction at around 1200 K, while their analogous PAHs (indene and fluorene) form a little later (~1000 K) with a maximum peak around 1500 K. This trend where OPAHs are formed and decomposed before PAHs was also observed by Suzuki et al in their oxidation study of non-oxygenated hydrocarbons like ethylene [9] and toluene [10] using a flow reactor.…”

“…Amongst recent studies in the literature, we can cite the work of Suzuki et al who have worked on the oxidation of ethylene [9] and toluene [10] using a flow reactor, whereby they identified the formation of benzofuran, dibenzofuran, 9-fluorenone and benzanthrone, and have proposed a sub-mechanism to explain the formation of benzofuran and dibenzofuran based on the theoretical works by Liu et al [11] and Shi et al [12]. The latter study consists of a developed mechanism to explain the formation of some OPAHs (benzofuran and dibenzofuran) via the HACA mechanism [13] from activated phenoxy radicals obtained from the oxidation of benzene.…”

Measurements of Intermediate Species in Fuel-Rich Oxidation of Ethylene, Toluene, and n-Decane

“…The effect of the equivalence ratio on the formation of small hydrocarbons was studied, as shown in Figures and at 1150 and 1300 K, respectively, varying the equivalence ratios from 3.0 to 12.0. Equivalence ratios larger than 3.0 were adopted in this study because PAHs were scarcely formed when the equivalence ratio was lower than 2.0 in our previous studies. , The nominal residence time was fixed to be 1.2 s. The detailed experimental conditions are presented in Table S2.…”

“…Equivalence ratios larger than 3.0 were adopted in this study because PAHs were scarcely formed when the equivalence ratio was lower than 2.0 in our previous studies. 11,12 The nominal residence time was fixed to be 1.2 s. The detailed experimental conditions are presented in Table S2.…”

“…Polycyclic aromatic hydrocarbons (PAHs), formed in fuel combustion and emitted from not only vehicles but also industrial machines, are well known as detrimental substances to the environment and human health. − Clarifying the detailed chemistry involving the formation and consumption of PAHs has been the target for decades because PAHs are considered as precursors for soot . The PAH formation is strongly dependent on the low-molecular-weight hydrocarbons, such as methane, acetylene, vinylacetylene, and others, that are formed in the oxidation and/or pyrolysis of fuel in the combustion environment and play an important role in the formation of PAHs. − According to some studies that report on the formation of PAHs, − clarifying the formation behavior of intermediate light hydrocarbons in the fuel-rich oxidation of hydrocarbons is very helpful for promoting the understanding of the reaction mechanism of PAHs and soot. The three selected hydrocarbons, namely ethylene, toluene, and n -decane, were employed as feedstocks in this study.…”