Effect of acid dissolution on the mineral matrix and organic matter of Zefa EFE oil shale

Abstract

Kerogen of the Israeli Zefa oil shale was isolated and the changes which occur in the initial organic matter during the removal of the inorganic matrix were investigated. Benzene-methanol extraction dissolved the bitumens, hydrochloric acid and hydrofluoric acid dissolution removed the carbonate and silicate minerals and lithium aluminium hydride treatment destroyed pyrite mineral which was unaffected by the attack of acids. X-ray diffractograms and FTIR spectra of the original oil shale and its demineralized products were measured. Benzene-methanol extraction of the oil shale increased the resolution of peaks in the X-ray diffractograms X-ray diffractograms and FTIR spectra indicated the presence of calcite, α-quartz, kaolinite, illite and pyrite in the mineral matrix of the shale. Hydrochloric and hydrofluoric acid dissolution did not cause hydrolysis and oxidation of the organic matter. Lithium aluminium hydride treatment reduced the carbonyl functionalities to newly formed hydroxyl groups, therefore the kerogen isolated seemed to have a chemical composition different from that of the original oil shale.