Determination of asphaltenes in fuels from coal hydrogenation

A method is described for the quantitative separation of coal-derived fuels into toluene insolubles, asphaltenes (toluene soluble, pentane insoluble), and oils (pentane soluble). The prime objective was to identify the variables in the procedure that affect the values obtained for asphaltene content. Substitution of toluene for benzene does not have a large effect on the values reported for either insolubles or asphaltenes. However, in order to obtain reproducible determinations, the precipitation of asphaltenes must be rigorously controlled. The precipitation is carried out by adding a large excess of pentane to a slurry prepared from the toluene solubles and toluene. A significant difference was found in the values determined for asphaltenes depending upon the amount of toluene used in the slurry. It is recommended that the amount of toluene in the slurry be equal to or greater than 3 mL/g solubles. 4 figures, 2 tables.