The combustion of gaseous aldehydes studied by flash photolysis and kinetic spectroscopy

Abstract

The identity and behaviour of free radicals produced during the combustion of gaseous aldehydes has been examined. The flash-initiated combustion of formaldehyde was investigated under conditions of slow and explosive combustion. The behaviour of formaldehyde and the derived radicals OH and HCO was followed during the course of the reaction. It was found that HCO radicals react rapidly with oxygen during the slow reaction, but decompose into H atoms and CO at the high temperatures produced during the explosive reaction. Further information on the reaction between HCO radicals and oxygen was obtained by flash - photolyzing gaseous formic acid in presence of oxygen and nitrogen under isothermal conditions. The results of this investigation are consistent with the kinetic observations previously made by Axford & Norrish. With one modification relating to the participation of HCO radicals they confirm the kinetic mechanism previously deduced by these authors. The flash-initiated combustion of acetaldehyde was also investigated under conditions of slow and explosive combustion, and information on several of the elementary reactions proceeding under these conditions has been obtained.