Determination of VOC-components in the exhaust of gasoline and diesel passenger cars

The composition of VOC emissions from in-use passenger cars with different engine types, i.e. cars with diesel engines, cars with petrol engines equipped with three-way-catalysts, and cars with petrol engines without catalysts was determined. Five cars of each engine type have been measured on a chassis dynamometer under conditions of the US FTP 75 test procedure and the “Autobahn” test developed by TÜV Rheinland. Measurements of C 2–C 10 hydrocarbons were made with a GC-FID system. In addition, samples on DNPH cartridges were taken and analysed by means of a HPLC-system for the determination of aldehydes and ketones.The influence of cold/warm-conditions on the VOC composition was determined. In the case of cars with diesel engines as well as for the petrol-driven cars without exhaust treatment, the effect caused by the cold start only led to minor changes in the VOC composition. A similar behaviour was observed for these car types at higher speeds. In contrast to the cars without catalysts, the cars with three-way-catalysts showed a great variability of the VOC composition. During the cold start phase the aromatic compounds and the alkenes yielded the main fraction of the VOC. During the warm phase the less reactive alkanes were predominant. With increasing mean velocities the VOC composition changed in favour of the more reactive compounds.