In order to evaluate the feasibility of coal derived middle distillates as diesel-powered automobile fuels, mass emissions of several substances (CO, HC, NOx, and particulate matter) in exhaust gas from two kinds of test automobiles were measured by operating the automobiles under 10 mode driving cycle, idling condition and constant speed conditions at 20, 40 and 60km/h. Also, compositions of soluble organic fraction, hydrocarbon type and polycyclic aromatic hydrocarbons in particulate matter were analyzed. The middle distillates were obtained from the liquefaction of Australian brown coal in a continuously operating bench unit and treated with catalytic hydrogenation in a batch autoclave. Two kinds of test fuels were prepared by mixing the middle distillates and a commercial gas oil.,
Mass emissions of CO, HC and particulate matter were exponentially increased with mixing percent of the middle distillates in the gas oil. Therefore, as far as mixing percent of the middle distillates was low, the extent of increase in mass emissions was small. The content of polycyclic aromatic hydrocarbon in particulate matter increased with the increase of the middle distillates, but the contents of total soluble organic, aliphatic, aromatic and polar fractions were not correlated with the middle distillates.
Aromatic hydrocarbon in the fuels significantly affected the emissions, which was the same tendency as petroleum derived fuels. Accordingly, it is desirable that the techniques for decreasing aromatic hydrocarbon content in coal derived middle distillates at catalytic hydrogenation are developed.
