The effect of diesel fuel compositions and distillation properties on PM production

Although overall demand for petroleum products is expected to decline, diesel fuel demand is projected to remain stable. Modern refineries produce diesel fuel by blending straight-run diesel fuel with cracked fractions like Light Cycle Oil (LCO) and kerosene. Cracked fractions are characterized by high concentrations of aromatic and naphthenic compounds compared to straight-run diesel fuel, whereas kerosene exhibits lighter distillation properties. This study quantitatively assesses the effects of diesel fuel composition and distillation properties on PM formation using engine bench tests designed to reflect practical refinery blending operations. To isolate the impact of fuel composition, test fuels were formulated with substantial variations in aromatic and naphthenic content, while other key parameters were held constant. To investigate the influence of distillation properties, two sets of test fuels were prepared: one series with varying front-end volatility achieved by adjusting kerosene content, and the other series with modified back-end volatility via cutting back-end fraction. A regression-based estimation equation for PM production was developed from experimental results, enabling quantification of the individual contributions of compositional and distillation parameters. The findings indicate that aromatic compounds have a greater influence on Particulate Matter (PM) formation than naphthenic compounds, with naphthenobenzene having a more pronounced effect than alkylbenzene. Furthermore, both aromatics and naphthene with polycyclic structures were found to contribute more substantially to PM emissions than their monocyclic counterparts. The study also confirms that enhancing the light-end volatility of diesel fuel - either through kerosene blending or cutting back-end fraction - effectively reduces PM production.