Theoretical kinetic study of the low temperature oxidation of ethanol

TL;DR

This study uses high-level quantum calculations to explore the low temperature oxidation pathways of ethanol, identifying key radicals and reactions that influence reactivity and potential ignition behavior.

Contribution

It provides a detailed theoretical analysis of hydroxyethylperoxy radical reactions in ethanol oxidation, highlighting new decomposition pathways and rate constants.

Findings

Hydroxyethylperoxy radicals mainly decompose to form HO2 radicals at low temperatures.

A decomposition route produces H atoms and formic peracid, enhancing ethanol reactivity.

Derived rate constants for reactions between 400 and 1000 K.

Abstract

In order to improve the understanding of the low temperature combustion of ethanol, high-level ab initio calculations were performed for elementary reactions involving hydroxyethylperoxy radicals. These radicals come from the addition of hydroxethyl radicals (?CH3CHOH and ?CH2CH2OH) on oxygen molecule. Unimolecular reactions involving hydroxyethylperoxy radicals and their radical products were studied at the CBS-QB3 level of theory. The results allowed to highlight the principal ways of decomposition of these radicals. Calculations of potential energy surfaces showed that the principal channels lead to the formation of HO2 radicals which can be considered, at low temperature, as slightly reactive. However, in the case of CH3CH(OOH)O? radicals, a route of decomposition yields H atom and formic peracid, which is a branching agent that can strongly enhance the reactivity of ethanol in low temperature oxidation. In addition to these analyses, high-pressure limit rate constants were derived in the temperature range 400 to 1000 K.