Extraction of kerogen from oil shale with supercritical carbon dioxide: Molecular dynamics simulations

The extraction process and mechanism of kerogen moieties with supercritical CO2 are elucidated using molecular dynamics simulations. It is demonstrated that supercritical CO2 can effectively dissolve the kerogen moieties adsorbed onto the shale surface, and the kerogen moieties dissolved in supercritical CO2 can be easily extracted from oil shale, because the interaction between the kerogen moieties dissolved in supercritical CO2 and the shale surface is greatly reduced. The dissolving capacity of supercritical CO2 is found to effectively increase with increasing pressure before the pressure reaches a critical value (approximately 50 MPa) and then increases slowly. Moreover, the dissolving capacity of supercritical CO2 increases with increasing temperature at high pressure, which is consistent with experimental results. In addition, the hydroxyl functional groups modified on the shale surface promote the extraction of kerogen moieties with supercritical CO2, and the polar kerogen moieties were more easily dissolved in supercritical CO2. (C) 2015 Elsevier B.V. All rights reserved.