A Novel Catalytic Hydrothermal System as a Green Approach for Sustainable Artificial Maturation of the Kerogen-Rich Low-Permeable Shale Rocks

Abstract The effectiveness of an iron nitrate catalyst (Fe(NO3)3·9H2O) was experimentally investigates to improve the efficiency of steam injection for in-situ hydrothermal conversion of Domanik low-permeable shale rock, with the aim of improving both the quantity and quality of produced synthetic oil. The experiments were performed under hydrothermal condition at 300℃ and 350℃ for 24 hours and at 400℃ for 3 hours. The generated synthetic oils and produced gases was analyzed using GC, GC-MS chromatography, gas chromatography, elemental and SARA analysis. The obtained results revealed that the addition of iron nitrate led to a significant increase in synthetic oil yield by 2.56% at 300℃, 5.39% at 350℃ and 4.87% at 400℃, as opposed to non-catalytic conditions. The optimal condition was identified at 350℃, which yielded higher amounts of light n-alkanes (C9-C20) compared to heavy n-alkanes. The results of SARA analysis and GC-MS also showed high aliphatic hydrocarbons content within the generated synthetic oil. Furthermore, XRD analysis revealed that the presence of iron sulfides (FeS2) and iron oxides (Fe2O3) plays a significant role in facilitating the effective desulfurization of bitumen and kerogen. These findings highlight the catalytic potential of water-soluble iron nitrate in hydrothermal treatment, offering valuable insights for optimizing synthetic oil production from oil shale.