Chemical modification and separation of preasphaltenes of SRC. Final report

Technical Report · Sun Mar 01 04:00:00 EST 1981

OSTI ID:6220171

Woolsey, N F; Baltisberger, R J

Several preasphaltenes isolated from lignite and bituminous coal solvent refining products were acetylated with radio labelled acetic anhydride. This allowed determination of the hydroxyl content and increased solubility in common solvents. Gel permeation chromatography of the acetylated preasphaltenes gave 8 to 10 fractions for each sample which were characterized by their hydroxyl content, nmr parameters, combustion analysis and molecular weight determinations. The molecular weight varied from ca. 250 to 1000. The preasphaltene prepared at 480/sup 0/C had the highest molecular weight average while the 400/sup 0/C sample has the lowest. Detailed analysis of the data showed the lower molecular weight fractions had higher hydroxyl contents probably accounting for their inclusion in this solubility class. Generally nmr parameters and OH content did not vary much with molecular weight. Comparison to available asphaltene data showed a higher molecular weight for preasphaltenes as expected. The hydroxyl content, however, was about the same with about one OH group for every average molecule throughout the fractions of both asphaltene and preasphaltene samples. The most obvious difference besides molecular weight was in ether oxygen which was about twice as large for preasphaltenes. It was postulated that asphaltenes have fewer more flexible ethers than preasphaltenes. As part of our investigation we initiated studies on quantitative, selective ether cleavage reactions. Boron tribromide and trimethylsilyl iodide cleave dialiphatic and arylaliphatic ethers. Sodium in hexamethylphosphoric triamide (HMPA) was found to cleave arylaliphatic and diaryl ethers. Dibenzofurans were stable to the conditions developed. Preliminary application to preasphaltenes showed borontribromide and sodium/HMPA each cleaved 11 to 22% of the ethers present. This preliminary result is consistent with the above structural postulates.

• Research Organization: North Dakota Univ., Grand Forks (USA)
• DOE Contract Number: FG22-78ET13380
• OSTI ID: 6220171
• Report Number(s): DOE/ET/13380-T1; ON: DE81030270
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010405 -- Coal
Lignite
& Peat-- Hydrogenation & Liquefaction
010600* -- Coal
Lignite
& Peat-- Properties & Composition
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ACETYLATION
ACYLATION
ALKALI METALS
AMIDES
ASPHALTENES
ASPHALTS
BITUMENS
BITUMINOUS COAL
BLACK COAL
BORON BROMIDES
BORON COMPOUNDS
BROMIDES
BROMINE COMPOUNDS
BROWN COAL
CARBONACEOUS MATERIALS
CHEMICAL REACTIONS
CHROMATOGRAPHY
COAL
COAL LIQUIDS
COMBUSTION
DECOMPOSITION
ELEMENTS
ENERGY SOURCES
ETHERS
FLUIDS
FOSSIL FUELS
FUELS
HALIDES
HALOGEN COMPOUNDS
LIGNITE
LIQUIDS
MATERIALS
METALS
MOLECULAR WEIGHT
NMR SPECTRA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
OTHER ORGANIC COMPOUNDS
OXIDATION
SEPARATION PROCESSES
SODIUM
SOLVENT-REFINED COAL
SPECTRA
STRUCTURAL CHEMICAL ANALYSIS
TAR
TEMPERATURE EFFECTS
THERMOCHEMICAL PROCESSES