Structural characterization of shale oil obtained by Soxhlet extraction

Organic matter recovery by solvent extraction has been the focus of numerous research area. In this work, recovery of organic matter from oil shale was evaluated by using Soxhelt extraction. Better oil extraction was reported after preheating of the shale to 300 degrees C in inert atmosphere. The extracted oil was fractionated to asphaltenes, aliphatics, aromatics, and polar compounds with percentages of 4.2%, 52.6%, 20.9%, and 22.3% respectively. Compared with thermal retorting, the oil obtained by solvent extraction has higher aliphatics and polar compounds. Following a proper design of experiments, oil recovery was correlated with the following experimental factors:Extraction OM% = 7.39 + 2.23 Temp + 0.20 Mass - 0.34 PS - 0.022 Ext Time + 0.13 Temp x Mass - 0.28 Temp x PS - 0.30 Mass x PS. The results indicated that preheating temperature and mass of oil shale were positively correlated with oil extraction. However, particle size/preheating temperature and mass/particle size were negatively interacted for better oil extraction. Optimum conditions for oil recovery were accomplished using tetrahydrofuran at solid-to-liquid ratio of 50:1 g/mL, particle size 200-250 mu m, and extraction time of 8.0 hr.