Some observations on the molecular nature of petroleum asphaltenes

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

OSTI ID:5720200

Speight, J G; Moschopedis, S E

Asphaltenes are dark brown to black friable solids that have no definite melting point and, when heated, usually intumesce, then decompose leaving a carbonaceous residue. They are obtained from petroleums and bitumens by addition of a nonpolar solvent (such as hydrocarbon) with a surface tension lower than 25 dynes cm/sup -1/ at 25/sup 0/C (such as liquefied petroleum gases, the low-boiling petroleum naphthas, petroleum ether, pentane, iso-pentane hexane, and the like). Asphaltenes are soluble in liquids having a surface tension above 25 dynes cm/sup -1/, such as pyridine, carbon disulfide, carbon tetrachloride, and benzene. Asphaltenes are, by definition, a solubility class which is precipitated from petroleums and bitumens by the addition of a minimum of 40 volumes of n-pentane. The elemental compositions of asphaltenes isolated by use of greater than 40 volumes of n-pentane as the precipitating medium (as near as can be determined) shows that the amounts of carbon and hydrogen usually vary over only a narrow range: 82 +- 3% carbon; 8.1 +- 0.7% hydrogen. The means by which the asphaltenes remain dispersed in the oil medium has been the subject of much speculation, but it is now clear that this is due to the resins. The general indications are that the degree of aromaticity and the proportion of heteroatoms in the resins play an important part in the ability of these materials to solubilize asphaltenes in an oil. The concept of hydrogen-bonding interactions being one of the means of association between the asphaltenes and resins has led to a reconsideration of the assumed asphaltene cluster as part of the micelle.

• Research Organization: Alberta Research Council, Edmonton
• OSTI ID: 5720200
• 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

02 PETROLEUM
023000* -- Petroleum-- Properties & Composition
04 OIL SHALES AND TAR SANDS
040500 -- Oil Shales & Tar Sands-- Properties & Composition
AROMATICS
ASPHALTENES
ASPHALTS
BITUMENS
CHEMICAL BONDS
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CLEAVAGE
COHERENT SCATTERING
CONDENSED AROMATICS
CRYSTAL STRUCTURE
DECOMPOSITION
DIFFRACTION
ENERGY SOURCES
FOSSIL FUELS
FRACTIONATION
FUELS
HETEROCYCLIC COMPOUNDS
MASS SPECTROSCOPY
MEASURING METHODS
MICROSTRUCTURE
MOLECULAR WEIGHT
ORGANIC COMPOUNDS
ORGANIC POLYMERS
OTHER ORGANIC COMPOUNDS
PETROCHEMICALS
PETROLEUM
PETROLEUM PRODUCTS
POLYMERS
PYROLYSIS
RESINS
SCATTERING
SEPARATION PROCESSES
SPECTROSCOPY
STRUCTURAL CHEMICAL ANALYSIS
SYNTHESIS
TAR
THERMOCHEMICAL PROCESSES
X-RAY DIFFRACTION