RECOVERY OF ORGANIC MATERIAL BY SUPERCRITICAL TOLUENE FROM TURKISH GOYNOK OIL SHALE 1. IDENTIFICATION OF THE MINERALS AND THEIR EFFECT ON THE RECOVERY OF OKGANIC MATERIAL

Abstract

ABSTRACT Effect of the mineral matrix on the recovery of organic material by supercritical toluene extraction from Turkish Göynük oil shale was investigated. Samples were prepared by successive demineralization procedures to study the interaction of different mineral groups during the supercritical interaction. Extraction experiments were done in a stainless steel autoclave of 75 ml capacity at 350°C for 60 minutes. Effect of the toluene/kerogon ratio and reaction time on the recovery of organic material was studied. Infrared spectra of the spent material uere measured to determine the structure of the organic material remaining after the supercritical treatment. The inorganic matrix of the shale was composed of calcite, silicate and pyrite minerals. Recovery of the organic material in the supercritical extraction experiments increased from 42% to 98% as the toluene/kerogen ratio was increased from 23.5 to 275. The extent of depolymerization seemed to be dependent on the to!uene/kerogen ratio and this suggested the possible cleavage of bonds due to solvent attack. Dissolution of carbonates and. Silicates decreased the organic material recovery extensively. The organic material recovered from the carbonate–free shale were about 50% lower than the organic material recovered from the original shale. Removal of pyrites did not affect the recovery of the organic matter. Percentage of the organic material recovered increased when CaCO3 Or SiO2 was added to kerogen and silicate free shale. These findings indicated that carbonate and silicate ninerals originally present in the shale might increase the organic matter recovery by supercritical toluene extraction. The raise of the toluene/kerogen ratio yielded more polar organic material. The aliphatic content of the recovered material was not affected by an increase in the toluene/kerogen ratio.