Sampling and analysis of volatile organic compounds emitted from leaded and unleaded gasoline powered motor vehicles

The C-3-C-10 volatile organic compounds (VOC) present in leaded and unleaded gasoline and the exhausts resulting from catalyst and noncatalyst vehicles tested with the European driving cycle have been analyzed in the present study. These tests have shown that the exhausts are enriched in prop-1-ene, n-but-1-ene, benzene, 2,2,4-trimethylpentane, ethylbenzene, styrene, o-xylene and naphthalene. Styrene allows the differentiation between emissions from catalyst and noncatalyst vehicles. Most of these compounds are highly reactive to photooxidation. Their formation and increase leads to more reactive VOC mixtures than those initially present in the gasolines. A higher proportion of aromatic compounds, including benzene, is observed in the catalyst vs. the noncatalyst vehicles. However, the total noncatalyst VOC yield is more than two times higher than that of the catalyst vehicles involving, in terms of absolute release, that the noncatalyst vehicles are responsible for higher emissions of aromatic hydrocarbons. The high relative proportion of aromatic VOC in the exhausts of both vehicles represents a major difference between the results of the European driving cycle and the VOC emissions observed in other tests (57-69% vs. 18-30%, respectively). The high abundances of aromatic compounds in the European test vehicle emissions are in good correspondence with the high proportion of these hydrocarbons in the urban air of cities such as Barcelona.