Oxidation rates of soot particulates by oxygen in the temperature range 1500–3500 K determined using a shock tube

Abstract

The oxidation rates of soot particulates have been studied at high temperatures (1500–3500 K) in a shock tube in oxygen–argon mixtures at pressures between 4 and 14 atm. Complex Arrhenius plots were found above 2200 K for the lower oxygen concentrations with the rate going through a maximum and then increasing again. Below 2200 K, simple Arrhenius plots were obtained and the order of reaction with respect to oxygen was found to be 0.5.A final expression for the rate ω was obtained: log(ω/g cm–2 s–1)= log A+ 0.5 log([O2]/mol cm–3)– [graphic omitted]6366//T[graphic omitted] with log A= 3.731 ± 0.1, giving an activation energy of 121.9 ± 2.5 kJ mol–1 or log(ω/g cm–2 s–1)= log B+ 0.5 log([P(O2)]/atm)– [graphic omitted]6048//T[graphic omitted] with log B= 0.946 ± 0.1, giving an activation energy of 115.8 ± 2.8 kJ mol–1. From these data the reaction probabilities, α, for the attack of oxygen molecules on soot can be calculated to be α= 3.45 exp[graphic omitted]–14919//T[graphic omitted] which yields an activation energy of 124 037 J mol–1.No effect of total pressure other than that due to increasing oxygen was found. The results have been compared with those obtained by other workers.