Study of the solubility of kerogen from oil shales (Puertollano, Spain) in supercritical toluene and methanol

In mixtures of bitumen–toluene and bitumen–methanol, supercritical equilibrium compositions were measured at 603.15, 613.15, 623.15 and 633.15 K (reduced temperatures 1.02, 1.04, 1.05 and 1.07) in a range of pressures of 4.5–14.5 MPa for toluene as solvent, and at 553.15; 583.15; 613.15 and 623.15 K (reduced temperatures 1.08, 1.14, 1.18 and 1.21) and pressures from 6.5 to 22.5 MPa for methanol as solvent. The solubility data were correlated by using Chrastil equation. At each temperature the number of molecules of solvent per molecule of solute was calculated for both toluene and methanol. Association numbers between 1.67 ± 0.02 and 2.47 ± 0.08 were obtained for toluene and 2.36 ± 0.10 and 2.60 ± 0.08 for methanol. In conclusion, association number was not independent of temperature. Also density data calculated with some equations of state (Peng-Robinson, Soave-Redlich-Kwong and Lee-Kesler) were compared to empirical density data in order to determine the effect of using any of them. Compounds obtained with each of solvents were analyzed using gas chromatography with a mass detector. Results obtained indicate that toluene extracts mainly aromatic compounds and little of paraffin and depletes the organic material in the oil shale. On the other hand with methanol lineal hydrocarbons insaturated and saturated with very little of aromatic compounds were obtained. This indicates that some reaction products are probably produced during the extraction process.