A comparison of retorting and supercritical extraction techniques on El-Lajjun oil shale

In this study the use of nitrogen retorting carbon dioxide retorting, supercritical CO2 extraction, and supercritical H2O are compared for oil yield, quality, and the types and amounts of compounds eluted from Jordanian El-Lajjun oil shale. Results show that supercritical H2O (SC-H2O) produces 50% higher yields than nitrogen retorting (R-N-2) while releasing higher molecular weight materials through solvation and pyrolysis. The use of supercritical CO2 (SC-CO2) provides the greatest production of mid-distillate compounds while producing the lowest overall yield due to the lack of pyrolysis. Retorting using CO2 (R-CO2) provides a narrower molecular-weight distribution than N-2 while improving the oil yield slightly. It is also established that shale oil can be extracted by supercritical fluid extraction that is operated at substantially lower temperatures, where solvation dominates pyrolysis as a predominant mechanistic step. The potential of El-Lajjun oil shale as a valuable energy source has also been analyzed.