Experimental and computational studies on the average molecular structure of Chinese Huadian oil shale kerogen

This study has defined the average molecular structure of kerogen from Huadian oil shale containing both atomic and molecular information. Pyrolysis–gas chromatography–mass spectroscopy (Py–GC–MS) has been used to chemically characterize the main structural skeleton in this kerogen. The geometry optimized configuration was obtained by molecular mechanics and molecular dynamics simulation methods. The constructed average structure was evaluated by simulation of 13C MAS NMR spectrum. The simulated value for the physical density was fitted in with experiment data. Based on the studies of reaction sites using semi-empirical method, we speculated that the kerogen pyrolysis can be divided into three stages. Such an average structure can serve as a starting point for theoretical studies on representations of the Huadian kerogen at molecular scale.

► Analytical pyrolysis was used to investigate the product distribution. ► An average structure was derived from assembling structural fragments. ► Then the structure was adjusted and evaluated by computer simulation technology. ► Reaction sites analyses and prediction in kerogen pyrolysis was carried out. ► This model can serve as a starting point for theoretical studies of Huadian kerogen.