Abstract

The effect of difluorodichloromethane additives on spark-discharge-initiated combustion of hydrogen and methane in air and oxygen media at atmospheric and reduced pressures has been investigated. It was found that the concentration limit of ignition of a premixed hydrogen–air mixture in the presence of difluorodichloromethane at 1 atm exceeds 10%. It was shown for the first time that the ignition limit of a premixed methane–air mixture is 1% of difluorodichloromethane, which is thus the most effective inhibitor of methane combustion. This also means that the active centers of hydrogen and methane combustion, which determine the development of combustion, have different chemical natures. Thus, the reaction with the participation of a difluorodichloromethane molecule leading to the formation of HF (ν = 2, 3) during the combustion of methane must include a stage with the participation of an active intermediate substance of methane combustion. Vibrationally excited HF molecules (ν = 2, 3) were first detected in products of hydrogen and methane oxidation reactions in the presence of difluorodichloromethane using visible and near-infrared hyperspectrometers. It has been established for the first time that HF molecules (ν = 3) during methane combustion are formed at the moment of reaching the maximum rate of chemical transformation; i.e., reactions involving CF₂Cl₂ molecules compete with the development of reaction chains.