The oxidation of 2-butene: A high pressure ignition delay, kinetic modeling study and reactivity comparison with isobutene and 1-butene

Butenes are intermediates ubiquitously formed by decomposition and oxidation of larger hydrocarbons (e.g. alkanes) or alcohols present in conventional or reformulated fuels. In this study, a series of novel ignition delay time (IDT) experiments of trans-2-butene were performed in a high-pressure shock tube (HPST) and in a rapid compression machine (RCM) under conditions of relevance to practical combustors. This is the first IDT data of trans-2-butene taken at engine relevant conditions, and the combination of HPST and RCM results greatly expands the range of data available for the oxidation of trans-2-butene to higher pressures (10-50 atm), lower temperatures (670-1350 K) and a wide range of equivalence ratios (0.5-2.0). A comprehensive chemical kinetic mechanism has simultaneously been developed to describe the combustion of trans-2-butene. It has been validated using the IDT data measured here in addition to a large variety of literature data: jet-stirred reactor (JSR) speciation data, premixed flame speciation data, flow reactor speciation data and laminar flame speed data. Moreover, the reactivity of trans-2-butene is compared to that of the other two isomers, 1-butene and isobutene, and these comparisons are discussed. Important reactions are highlighted via flux and sensitivity analyses and help explain the differences in reactivity among the butene isomers.