Interaction between Organic Solvents and Three Types of Kerogen Investigated via X‑ray Diffraction

In this work, for the first time, a new swelling method was applied to study the chemical structure of kerogen. Structural changes during the swelling process were detected via X-ray diffraction (XRD). Three types of kerogen samples and three organic solvents were selected for this study. It was found that kerogens have a selective absorption of aromatic hydrocarbons compared with saturated hydrocarbons. Type I kerogen demonstrated the strongest ability to sorb hydrocarbons; it can sorb more than half of its own weight at normal temperature and pressure (25 °C and 1.013 × 10⁵ Pa). However, under the same conditions, type III kerogen can sorb around 40% of its own weight. XRD detection revealed that the microcrystalline structure of kerogen was not affected by liquid organic matter during the swelling process. Three kinds of organic solvent are mainly sorbed in the γ band (amorphous carbon) comprising aliphatic carbon, and the γ band swells under the swelling action, causing the value of d_γ to increase. This study explored the ability of kerogen to sorb hydrocarbon compounds and discovered the chemical structural units that occur in kerogen during solvent swelling. It is of great significance for the study of the hydrocarbon generation and expulsion in oil shale under geological conditions and the structure of kerogen.