ION EXCHANGE CHROMATOGRAPHY SEPARATION OF SHRP ASPHALTS

• Published in: Fuel science & technology international 1992-01, Vol.10 (4-6), p.855-885
• Main Authors: Branthaver, J.F., Catalfomo, M.W., Petersen, J.C.
• Format: Article
• Language: English
• Subjects: Applied sciences; Bitumen. Tars. Bituminous binders and bituminous concretes; Buildings. Public works; Crude oil, natural gas and petroleum products; Energy; Exact sciences and technology; Fuels; Materials; Petroleum products, gas and fuels. Motor fuels, lubricants and asphalts
• ISSN: 0884-3759
• DOI: 10.1080/08843759208916025

Eight asphalts selected for intensive study in the Strategic Highway Research Program have been separated into neutral, basic, and acidic fractions by means of ion exchange chromatography. Each asphalt exhibits a characteristic fractionation pattern into neutral, acidic, and basic components. The separations into chemical types were verified by elemental analysis and infrared methods. Separations were reasonably repeatable, and recoveries were acceptable. Large enough amounts of asphalts could be separated so that properties of interest of the fractions could be studied. In all cases, neutral fractions comprised at leaBt one-half of the asphalts. These neutral fractions are the least aromatic and contain the lowest percentages of heteroatoms and metals compared with the polar fractions. They also are much lower in molecular weight. The viscosities of the neutral fractions are at least two orders of magnitude lower than parent asphalt viscosities measured at the same temperature and rate of shear. The neutral fractions have properties predicted by a model of asphalt structure, which postulates that polar, aromatic materials are dispersed in a less aromatic, nonpolar solvent phase The polar fractions are friable solids or tacky semisolids. Them polar fractions also have properties predicted for dispersed phases in the above mentioned model of asphalt structure. They are more aromatic, contain larger percentages of heteroatoms, and are of higher molecular weight than neutral fractions. The polar fraction designated as the strong acid fraction is the most abundant an d most aromatic of the ion exchange chromatography polar fractions. and it also contains the largest concentration of polar functional groups