Quadratic autocatalysis and self-heating in hydrocarbon oxidation

Abstract

The oxidation of normal butane under very fuel-rich conditions leads to isothermal reaction which obeys a quadratic autocatalytic rate law. When self-heating occurs the maximum rate is reached only in the final stages of the ‘slow’ reaction. The accompanying chemiluminescent emission (from CH2O*) is identified as the ‘pic d' arrêt’; it results form the enhancement of free-radical concetrations as the maximum of the authocatalytic reaction rate is reached under non-isothermal conditions. Criticality, leading to cool-flame phenomena at sub-atmospheric pressures, takes place as a result of the autocatalysis accompanied by self-heating.