The effect of various parameters on the supercritical extraction of Moroccan oil shales: Application in the elaboration of carbon foams and graphitizable carbons

This study evaluates the possibilities to produce new materials, starting from Moroccan oil shales, for different applications. More specifically, the authors aimed to demonstrate that the organic fraction of the oil shales could be used as a precursor of carbon foams and graphitizable carbons, after appropriate chemical treatments resulting in the “maturation” of this organic phase. First, the researchers studied the optimization of experimental conditions and the identification of various parameters influencing the yield and composition of oils obtained by the supercritical extraction of Moroccan oil shale. The effect of various experimental parameters, such as mineral matter, thermal treatment temperature (T), treatment duration (t) and solvent type, was studied. The experimental results obtained show clearly that the organic matter contained in the Moroccan Tarfaya oil shale (sub-layer R3 ) can be recovered by phenol under the following optimal conditions: T = 390 °C, t = 2.5 hours using phenol as a solvent with an amount of 15 g for each 10 g of sub-layer R3 carbonate-free oil shale (RH). The results reveal that the yield and composition of the oil obtained by extraction with phenol is markedly different from those obtained by extraction with toluene, quinoline or without solvent. Furthermore, the phenol has a very significant role in increasing the recovery yield and the degree of maturation of the obtained oil. It was shown that phenol was a suitable extraction solvent to produce graphitizable carbon at a relatively low temperature, below 1800 °C.