Submitted to: Petroleum Science and Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/10/2006
Publication Date: 2/27/2007
Citation: Sharma, B.K., Sharma, C.D., Tyagi, O.S., Bhagat, S.D., Erhan, S.Z. 2007. Structural characterization of asphaltenes and ethyl acetate insoluble fractions of petroleum vacuum residues. Petroleum Science and Technology. 25:121-139. Interpretive Summary: The fraction of petroleum crude oil which boils at temperatures above 530 deg C are called residues. The insoluble fractions of these residues were obtained by precipitation in n-hexane, n-heptane and ethyl acetate solvents, and also by further reprecipitation of n-heptane and ethyl acetate soluble fractions by n-pentane. These insolubles are part of heavier components, which results in formation of molecular aggregates of different sizes and compositions in petroleum crude oil. These insolubles have drawn considerable attention due to problems caused by their harmful effects in both production and refining of crude oils because of their viscous and aggregate formation nature. These insoluble fractions were structurally characterized to study the effect of solvent on these fractions. These fractions were also characterized to determine their chemical nature and average molecular structure.
Technical Abstract: Asphaltenes and insoluble fractions of vacuum residues (VRs) of two Indian crude oils (viz. Heera and Jodhpur) of different specific gravity were obtained by precipitation of VRs in n-hexane, n-heptane and ethyl acetate, and also by subsequent reprecipitation of n-heptane and ethyl acetate soluble fractions by n-pentane. These asphaltenes and insolubles were characterized by NMR, FTIR and SEC to study the effect of solvent on these fractions. These fractions were also characterized to determine their chemical nature and average molecular structure. As compared to Heera VR, Jodhpur VR produced larger amounts of insolubles containing high molecular weight species having high concentration of condensed and substituted aromatic rings, branched and/or short alkyl side chains, oxygen and nitrogen functionalities.