Separation and characterization of lignite derived preasphaltenes by gel permeation chromatography and nuclear magnetic resonance spectrometry
Preasphaltenes for purposes of this study are defined as that portion of a lignite derived product which is soluble in tetrahydrofuran but insoluble in toluene. The preasphaltenes studied would fall into the seventh and eighth fractions of the sequential elution by solvent chromatography (SESC) procedure. The preasphaltene fraction was chromatographed for size separation using Bio-Beads S-X3 columns and pyridine as the eluent. The distribution and functionality of nitrogen and oxygen were then monitored in the molecular size fractions formed at different operating conditions. The study shows the structure and distribution of oxygen is the most important parameter. Work was centered on the development of procedures of the quantitation of oxygen functionality in this material. For this report it was only possible to identify the amount of phenolic hydroxyl groups present. Gel permeation chromatography offers the opportunity to observe subtle changes in preasphaltene structure that would be rather difficult to observe by another procedure. The postulated aromatic core plus ether links polymer structure requires precise information about the concentration of phenolic sites as they change with molecular weight. The type of preasphaltene structure suggested by this study would explain why preasphaltenes are insoluble in benzene even through their acidities, bascities and fraction of aromatic carbons may be equal to those of asphaltenes. Their insolubilities result from ether and furan linkages locking the aromatic systems into very rigid condensed molecules.
- Research Organization:
- Univ. of North Dakota, Grand Forks
- OSTI ID:
- 6494751
- Report Number(s):
- CONF-810308-(Vol.4)
- Journal Information:
- Am. Chem. Soc., Div. Fuel Chem., Prepr.; (United States), Journal Name: Am. Chem. Soc., Div. Fuel Chem., Prepr.; (United States) Vol. 26:2; ISSN ACFPA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Synthesis of oligomeric models of coal-derived materials for use with GPC calibration. Quarterly report, June-August 1982. [Gel permeation chromatography]
Chemistry of lignite liquefaction. Quarterly report for the period January-March, 1982
Related Subjects
010600* -- Coal
Lignite
& Peat-- Properties & Composition
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400104 -- Spectral Procedures-- (-1987)
400105 -- Separation Procedures
AROMATICS
ASPHALTENES
ASPHALTS
BITUMENS
BROWN COAL
CARBONACEOUS MATERIALS
CHROMATOGRAPHY
COAL
COAL LIQUIDS
COMPARATIVE EVALUATIONS
ENERGY SOURCES
ETHERS
EXTRACTION
FLUIDS
FOSSIL FUELS
FUELS
FURANS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
HYDROXY COMPOUNDS
LIGNITE
LIQUIDS
MAGNETIC RESONANCE
MATERIALS
MOLECULAR WEIGHT
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OTHER ORGANIC COMPOUNDS
PHENOLS
RESONANCE
SEPARATION PROCESSES
SOLVENT EXTRACTION
SOLVENT-REFINED COAL
SPECTRA
SPECTROSCOPY
TAR
TETRAHYDROFURAN
TOLUENE