Experimental and modeling study of styrene oxidation in spherical reactor and shock tube

Abstract

The oxidation of styrene, one of the main stable intermediates from the oxidation of large alkylated aromatic hydrocarbons, has been investigated in the present work both experimentally and numerically. Experiments were performed using two complementary techniques, spherical bomb for laminar flame speed studies and shock tube for ignition delay time measurements. In particular, the laminar flame speeds of styrene/air mixtures were measured at three different initial temperatures (342 K, 373 K, and 405 K), over a wide range of equivalence ratios (0.75–1.45), for an initial pressure of 100 kPa. In addition, the autoignition of styrene/O2 mixtures in argon bath gas (ϕ = 0.5, 1.0, and 1.5) was investigated over a wide range of temperatures (1390–1990 K), at highly diluted conditions (94.3%–99% argon), and for pressures between 110 and 200 kPa. A detailed chemical kinetic model, based on the toluene chemistry by Metcalfe et al. (2011), was developed and validated against the newly obtained experimental results and the flow reactor data available in the literature (Litzinger et al., 1986). Sensitivity and rate of production analyses were performed and showed that, at the conditions studied herein for the flame speed investigation, the main fuel consumption pathways include the reaction of the fuel with H atoms to form phenyl radical and ethylene or benzene and vinyl radical, with O to form benzyl radical + HCO, and the H-abstraction reactions on both the vinyl moiety and the ring. On the other hand, the analyses performed at the high-temperature, highly-diluted conditions encountered in the shock tube study highlighted the importance of the fuel thermal decomposition steps for the simulation of the ignition delay time measurements. The model was also tested against the low-pressure flame and jet stirred reactor data by Yuan et al. (2015). The results highlight the need for future modifications in the benzene chemistry by Metcalfe et al. and inclusion of pressure dependent rate parameters in order to improve the prediction capabilities of the model.