Study of low and high temperature oxidation of n-pentane at supercritical conditions in a jet stirred reactor

Abstract

The intermediate/low and high temperature oxidation of n-pentane from atmospheric pressure to supercritical pressures (1-100 atm) was studied by using Chemkin, a commercial software. A recently developed n-pentane model was used to predict the temperature evolutions of major and intermediate species, like n-pentane, O2, CO, CO2, CH2O, C2H4, CH3CHO at varied pressure and temperature conditions. It is found that as the environmental pressure increases, the difference between high temperature oxidation and low temperature oxidation becomes less obvious because the negative temperature coefficient (NTC) is decreasing (at 10 atm and 100 atm, high temperature oxidation occurs right after low temperature oxidation). At supercritical pressures, the high temperature oxidation is governed by the branching reactions of RO2, and the addition reaction of QOOH with oxygen dominates the reaction paths at both low and high temperature oxidations because the addition reaction between QOOH and oxygen is still more important than the decomposition reaction of QOOH at high temperature and 100 atm. According to the pathway analysis and sensitivity analysis, the branching reactions of RO2 are dominating at both low and intermediate to high temperatures.