Wspólnotowy Serwis Informacyjny Badan i Rozwoju - CORDIS


MOST Streszczenie raportu

Project ID: EVK2-CT-2001-00114
Źródło dofinansowania: FP5-EESD
Kraj: France

Gas phase mechanistic and kinetic data on the degradation of key oxygenated compounds

Vinyl Ethers are used in different industries, particularly as solvents, as motor oil additives and for coatings. They are released into the atmosphere where they are available for photochemical transformation. The atmospheric oxidation of these oxygenated compounds can contribute to the formation of ozone and other secondary pollutants. In the troposphere, these unsaturated compounds react with OH and NO3 radicals and with O3. Kinetic and mechanistic data are needed in order to determine the lifetimes of these compounds in the troposphere and to assess their contribution to urban and regional pollution.

Within the MOST project, rate coefficients and product yields for the gas phase reactions of a series of vinyl ethers with the most important atmospheric oxidants have been determined (for the first time for most reactions). The ozonolysis, OH and NO3 reactions lead to the formation of alkyl formates in high yield. For the vinyl and divinyl ethers HCHO was found to be the major co-product in the reactions with OH. In the case of the ozone reactions with vinyl and divinyl ethers the co-products are mainly determined by reactions of the CH2OO Criegee intermediate. The obtained results provide information about the atmospheric fate and impact of the investigated compounds. The rate data obtained contribute to better define their tropospheric lifetime. The unsaturated ethers have lifetimes of few hours; they are removed from the atmosphere in the gas phase by reaction with OH, NO3 and O3. Their oxidation leads mainly to formates and aldehydes. Aerosol formation was observed in the ozonolysis of all vinyl ethers and ethyleneglycol vinyl ethers.

The rather short-lived unsaturated ethers could have a local impact, which however is not only defined by the persistence of these compounds but also by the fate of their oxidation products. Aldehydes will be removed by photolysis or reaction with OH and have lifetimes of less than a day while alkyl formates will be oxidised mainly by reaction with OH radicals leading to acids and anhydrides which are highly soluble and may be rapidly incorporated into cloud droplets. Alkyl formates have lifetimes of weeks, which may reduce significantly the local impact of unsaturated ethers.

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