Molecular Weight and Association of Asphaltenes: a Critical Review

摘要: The determination of asphaltene molecular weights is complicated by the tendency molecules to associate with each other and petroleum constituents, reported vary from 900 300 000. This paper reviews methods (vapor pressure osmometry, size exclusion chromatography, ultrafiltration, ultracentrifugation, viscosity, small angle X-ray scattering, infrared spectroscopy, solubilization, interfacial tension) that have been used estimate probe association phenomena. It concluded fractions typical crudes a number average weight 1 200-2 700 range 1,000-10,000 or higher. Intermolecular phenomena are primarily responsible for observed up in excess 100,000 but detailed mechanisms intermolecular associations not well understood. Certain observations suggest associated reversedmicelles asphaltenes interact selectively resins although evidence on these points subject alternate interpretations. H-bond interactions between demonstrated.