The development of a detailed chemical kinetic mechanism for diisobutylene and comparison to shock tube ignition times

Shock tube experiments and chemical kinetic modeling were carried out on 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene, the two isomers of diisobutylene, a compound intended for use as an alkene component in a surrogate diesel. Ignition delay times were obtained behind reflected shock waves at 1 and 4 atm, and between temperatures of 1200 and 1550 K. Equivalence ratios ranging from 1.0 to 0.25 were examined for the 1-pentene isomer. A comparative study was carried out on the 2-pentene isomer and on the blend of the two isomers. It was found that the 2-pentene isomer ignited significantly faster under shock tube conditions than the 1-pentene isomer and that the ignition delay times for the blend were directly dependant on the proportions of each isomer. These characteristics were successfully predicted using a detailed chemical kinetic mechanism. It was found that reactions involving isobutene were important in the decomposition of the 1-pentene isomer. The 2-pentene isomer reacted through a different pathway involving resonantly stabilized radicals, highlighting the effect on the chemistry of a slight change in molecular structure.