The combustion properties of 1,3,5-trimethylbenzene and a kinetic model

Trimethylbenzenes have been suggested as useful components for the formulation of simple hydrocarbon mixtures that quantitatively emulate the gas-phase combustion behaviour of real liquid transportation fuels as model or surrogate fuels. To facilitate this application, various combustion properties of 1,3,5-trimethylbenzene (mesitylene) have been characterised experimentally and a new chemical kinetic model for its combustion constructed. Experimental determinations of 1,3,5-trimethylbenzene reflected shock ignition delay, laminar burning velocities and high-pressure flow reactor oxidative reactivity profiles are presented. These data allow for the testing of a detailed kinetic model, developed by direct analogy to, and incorporating as a subcomponent, a recent comprehensively tested kinetic model for toluene oxidation [Metcalfe WK, Dooley S, Dryer FL. Energy Fuels 2011; 25: 4915-4936]. Model calculations are also compared against data pertinent to 1,3,5-trimethylbenzene combustion phenomena from the published literature. The modelling approach allows for the accurate reproduction of the global combustion phenomena of ignition delay, burning velocity, diffusive and premixed strained extinction limits and flow reactor reactivity, with some noted shortcomings. Analyses of the constructed model suggest that the mechanism of 1,3,5-trimethylbenzene combustion occurs through the formation of 3,5-dimethylbenzaldehyde and 1,2-bis(3,5-dimethylphenyl) ethane as the major stable intermediate species, with relative proportions depending on the conditions of the particular reacting environment.