Organic emissions profile for a light-duty diesel vehicle

In this report we describe the speciated gas-phase hydrocarbon and carbonyl emissions as collected from a recent model automobile powered by a 2.5l indirect injection diesel engine and outfitted with a production oxidation catalyst for exhaust after-treatment. The vehicle was run on a typical low sulfur (500 ppm S) European diesel fuel and measurements were made over the European MVEG test cycle. The diluted tailpipe emissions were sampled for light hydrocarbons (C-1-C-12) using Tedlar bags and semi-volatile hydrocarbons (C-12-C20+) using Tenax cartridges. Both the light and semi-volatile hydrocarbon fractions were speciated using capillary gas chromatography. Combining the two sets of speciation data provided a profile of the gas-phase hydrocarbon emissions from a light duty diesel vehicle. Of the total gas phase non-methane hydrocarbons emitted, 80% were accounted for in the light hydrocarbon fraction, and 20% in the semi-volatile fraction. The semi-volatile fraction, which extended only to about C-15, was composed almost entirely of unburned fuel molecules, but with enrichment of the aromatic species relative to the fuel itself. n-Alkanes (paraffins) and methylnaphthalenes accounted for approximately 37% of the semi-volatile fraction. Aldehydes and ketones represented 34% of NMOG. Formaldehyde and acetaldehyde, account for 74% of the total carbonyl emissions. (C) 1999 Elsevier Science Ltd. All rights reserved.