Experimental and kinetic investigation of 1,2,4-trimethylbenzene oxidation at low temperature

The oxidation of 1,2,4-trimethylbenzene (TMB124) for equivalence ratio of 2.0 was studied in a Jet-stirred reactor over the temperature range of 700-1100 K at atmospheric pressure. Mole fraction profiles of 22 species, including reactants, intermediates, and products were identified by on-line GC analysis. Based on the measurements and theoretical calculations, a detailed chemical kinetic model involving 544 species and 3248 reactions was established. Rate constants of TMB124 decomposition, reaction with HO2, ipso-additions and metatheses with abstraction of methyl H-atom were updated. New pathways of H-abstraction from the 1- and 2-methyl groups were considered. The final model leads to an overall satisfactory agreement between the experimental observations and predictions for the major species and intermediates. Rate-of-production analysis indicates that the TMB124 consumption is dominated by metatheses giving three dimethyl benzyl radicals. From the sensitivity analysis, it is obvious that the reactions of HO2 radical and the three dimethyl benzyl radicals have promoting effect, while the H-abstraction reactions of TMB124 exhibit strong inhibiting effect. These results will enrich the understanding of low temperature chemistry of TMB124 and facilitate to further model development and validation.