Experimental and Molecular Simulation Studies of Huadian Oil Shale Kerogen

Microscopic details on the intrinsic chemical reactivity of Huadian oil shale kerogen associated with electron properties of kerogen were investigated by the combination of experimental analyses and molecular simulations. Multimolecular structure models of kerogen with different densities were constructed for examining the accuracy of the proposed kerogen model. Results revealed that the simulated density of the kerogen model is in good agreement with the experimental value. Evaluation of the kerogen model revealed that the energy optimization process is mainly related to the change in the bond angle caused by atom displacement. According to the results from the Hirshfeld analysis of atomic charges, the S atoms in thiophene and S=O structures exhibit positive charges. By contrast, the concentration of electrons on the S atom led to the electronegativity of the sulfhydryl group. To investigate the distribution characteristics of electrons in kerogen, the molecular electrostatic potential (MEP) of a complete kerogen molecule was calculated. Notably, this is the first report of an MEP diagram of the kerogen model that can provide valuable information on the determination of electrophilic or nucleophilic reaction sites for kerogen.