Separation of Asphaltene by Dimethyl Ether

Abstract

Solvent deasphalting (SDA) of heavy oil generally uses alkanes, from propane to heptane. The solvent power of propane is the weakest, and that of heptane is the strongest. Ethyl ether has slightly stronger solvent power than heptane. Dimethyl ether (DME), an alternative to diesel fuels, is thus expected to have good solvent power for SDA. DME was used for asphaltene separation from vacuum residue of Arabian Light crude oil (AL-VR) at DME/AL-VR weight ratio of 10-60, and compared with separation using pentane by the conventional method. The recoveries of maltene and asphaltene were comparable with pentane more at DME/AL-VR ratio by weight of over 40. Both maltene and asphaltene recovered by DME and pentane had almost the same H/C atomic ratio, hydrogen distribution and carbon aromaticity, respectively. The deasphalting performance of DME was equivalent to that of pentane.