The reaction of hydroxyethyl radicals with O2:A theoretical analysis and experimental product study

摘要

Reactions of a-hydroxyethyl (CH3CHOH) and b-hydroxyethyl (CH2CH2OH) radicals with oxygen areof key importance in ethanol combustion. High-level ab initio calculations of the potential energy surfacesof these two reactions were coupled with master equation methods to compute rate coefficients and productbranching ratios for temperatures of 250–1000 K. The a-hydroxyethyl + O2 reaction is controlled by thebarrierless entrance channel and shows negligible pressure dependence; in contrast, the reaction of the bisomer displays pronounced pressure dependence. The high pressure limit rate coefficients of both reactionsare about the same at the temperatures investigated. Products of the reactions were monitored experimentallyat 4 Torr and 300–600 K using tunable synchrotron photoionization mass spectrometry. Hydroxyethylradicals were produced from the reaction of ethanol with chlorine atoms and the b isomer wasalso selectively produced by the addition reaction C2H4+OH→ CH2CH2OH. Formaldehyde, acetaldehyde,vinyl alcohol and H2O2 products were detected, in qualitative agreement with the theoreticalpredictions.