Coal-derived asphaltenes. Relationship between chemical character and process history

• Published in: Fuel processing technology 1979-01, Vol.2 (2), p.143-153
• Main Authors: Bockrath, Bradley C., Noceti, Richard P.
• Format: Article
• Language: English
• ISSN: 0378-3820; 1873-7188
• DOI: 10.1016/0378-3820(79)90015-8

The chemical character of asphaltenes isolated from coal-derived liquids and the relative ease of their catalytic and noncatalytic conversion to oil has been found to depend upon their processing history. To facilitate chemical characterization, a simple analytical method was developed for separation of the asphaltenes into three subfractions according to their relative strength of absorption on silica gel. Using this separation technique, differences in the relative content of polar molecules were found among asphaltenes of various processing histories. In general, the relative content of polar compounds in the asphaltenes decreases with increasing conversion to oil. The relative rate of conversion also declines after the asphaltene content reaches a low level. The asphaltenes remaining after long hydrotreatment are more aromatic, contain fewer polar functional groups and are of somewhat smaller molecular size than those obtained after short hydrotreatment. The initial rates of asphaltene conversion were considerably enhanced by a commercial CoMo hydrodesulfurization catalyst. The catalyst increased the conversion of the nonpolar subfraction to a greater extent than the polar subfraction.