Diesel fuel aromatic content and its relationship with emissions from diesel engines

Report no. 92/54: This report provides the results of a research programme designed to investigate the influence of diesel fuel aromatic content arid cetane number on diesel engine exhaust emissions. A representative range of seven current light-duty vehicles, together with two heavy-duty engines, was tested using European test procedures with six fuels having aromatics contents in the range 15 to 37% volume.

The test fuels were produced by deep hydrogenation of the base fuel. This process influences other fuel quality parameters, including density, sulphur content and cetane number. To balance these changes the matrix included sulphur and ignition improver additive-doped fuels.

A hydro cracked fuel was also included in order to study the influence of aromatic type.The study found a significant influence of fuel properties on carbon monoxide and particulate emissions from light-duty vehicles. The strongest correlations were obtained with cetane number. Inclusion of aromatics terms in correlation equations with cetane number gave no improvement over correlations incorporating only cetane number.