Detailed kinetic modeling for the organic-rich oil shale upgrading using supercritical water

The lack of detailed reaction models for the upgrading of oil shale using supercritical water (SCW) is the driving force of this work. An investigation involving a complex reaction scheme was conducted, incorporating oil shale, liquid, and gas fractions with detailed composition. The resulting kinetic model effectively agrees with the experimental data, being the gases with high yields (CO₂, and hydrocarbon gases) more difficult to be predicted. Additionally, the developed kinetic model can adequately predict the experimental yield of some products from oil shale upgrading with similar composition. At low temperatures (380 °C), organic compounds within oil shale primarily undergo dealkylation reactions, leading to the production of synthetic oil and coke. Subsequently, the coke is decomposed into CO₂ and molecules resembling kerogen. Temperatures exceeding 400 °C led to a substantial transformation of kerogen into hydrocarbon gases and coke, with secondary cracking of coke generating primarily CO₂ and synthetic oil. This latter undergoes over-cracking reactions, producing hydrocarbon gases. The inorganic matter primarily decomposed into CO₂, with a smaller proportion forming CO. The H₂ formation was predominantly attributed to the disintegration of organic matter at 380 °C, with the water-gas shift reaction emerging as the principal source of H₂ at temperatures exceeding 400 °C. The production of H₂S is mainly associated with the decomposition of organic compounds. Extending the reaction time and raising the temperature led to improved oil shale conversion until reaching optimal conditions at 380 °C for 6 h. Beyond these conditions, further increases in parameters directly impacted the yield of synthetic oil.