Structural characterization of coal-derived asphaltenes and its significance to liquefaction

Conference · Sat Sep 01 04:00:00 EDT 1979 · Am. Chem. Soc., Div. Pet. Chem., Prepr.; (United States)

OSTI ID:5539087

Bockrath, B C; Schweighardt, F K

Comparisons between asphaltenes derived from bituminous coal liquefaction and those derived from petroleum crudes are summarized. It is evident that the molecular size and atomic H/C ratios suggest a molecular profile quite different for the two asphaltenes. Benzene solubility of petroleum asphaltenes is apparently due to the structural arrangement of the long aliphatic sidechains on aromatic rings. Coal-derived asphaltenes are benzene soluble due to their smaller size-lower molecular weight and the greater concentration of functional groups. The nature of the functional groups also appears to be different, e.g., oxygen appears as hydroxyl and ether moieties in coal-derived asphaltenes, while petroleum asphaltenes contain hydroxyl, carbonyl and some ether linkages. Nitrogen, as well as oxygen, has only two predominant forms in coal asphaltenes, NH and base nitrogen -N=, while petroleum contains, in addition to those groups NH/sub 2/ functions. Liquefaction processing conditions greatly influence the properties of coal-derived asphaltenes. It is difficult to make generalizations from the limited and widely scattered data available, but we may point out the results of our recent study of asphaltene character as a function of processing history. In this study, a liquid product containing 31.7 percent asphaltenes was hydrotreated in a stirred autoclave under a variety of conditions, both with and without a CoMo catalyst, so that various amounts of conversion to pentane soluble oils were obtained. It was found that the asphaltenes remaining after hydrotreatment were more aromatic, contained fewer polar functional groups, and were of somewhat smaller average molecular size than those present before hydrotreating. The chemical character of the unconverted asphaltenes is also a function of processing. Both the H/C and O/C atomic ratios declined in a regular manner as conversion progressed.

• Research Organization: Pittsburgh Energy Tech. Center, PA
• OSTI ID: 5539087
• Report Number(s): CONF-790917-(Vol.24)(No.4)
• Conference Information: Journal Name: Am. Chem. Soc., Div. Pet. Chem., Prepr.; (United States) Journal Volume: 24:4
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010405* -- Coal
Lignite
& Peat-- Hydrogenation & Liquefaction
ASPHALTENES
ASPHALTS
BITUMENS
CARBONACEOUS MATERIALS
CHEMICAL PREPARATION
CHEMICAL REACTIONS
COAL
COAL LIQUEFACTION
COAL LIQUIDS
COMPARATIVE EVALUATIONS
ENERGY SOURCES
FOSSIL FUELS
FUELS
HYDROGENATION
LIQUEFACTION
ORGANIC COMPOUNDS
OTHER ORGANIC COMPOUNDS
PETROLEUM
SYNTHESIS
TAR
THERMOCHEMICAL PROCESSES