Single Pulse Shock Tube Study on the Effects of Double Bond Position in Unsaturated Hydrocarbons and Fatty Acid Methyl Esters

摘要

High pressure, single pulse shock tube oxidation experiments were conducted in order to probe the chemical kinetic effects of the double bond position in unsaturated biodiesel molecules. Methyl trans-2-nonenoate and methyl trans-3-nonenoate were used to represent the isomers of a monounsaturated biodiesel component. Additional experiments with 1-octene and trans-2-octene were conducted to investigate the kinetics of the unsaturated alkenyl side-chain alone. All oxidation experiments were carried out with approximately 100 ppm of each fuel, in argon, at stoichiometric conditions. The experimental conditions covered the pressure range of 40-60 bar and temperature range of 850 - 1500 K, with an average reaction time of 1.7 ms. Gas chromatographic measurements of the stable intermediates indicated an increased reactivity in the experiments in octenes when the double bond was moved toward the center. Significantly different yields in most of the intermediate species measured were observed. Similar experiments with several decene isomers support these results. The results for the methyl nonenoate isomers showed a difference in the relative yields of some stable intermediates but no increase in reactivity. These results suggest a possible reaction dampening effect of the ester group, commonly thought to react independently of the alkenyl side chain.