Chemical Structure Investigation of Maoming Oil Shale Kerogen by Supercritical Gas Extraction

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Abstract
A yield of toluene-soluble bitumen as high as 80 percent of the organic matter, has been obtained for a Chinese oil shale at Maoming, Guangdong Province, by means of supercritical gaseous toluene extraction. The structure of bitumen was investigated by a variety of analytical methods, such as solvent and chromatographic fractionation, ultimate analyses, molecular weight determination, infrared spectroscopy, electron spin resonance, and gas liquid chromatography. In the light of analytical results, it is revealed that mild thermal depolymerization takes place during extraction, and the oil shale kerogen has the character of a multipolymer. The average unit weight of the “building block” of the kerogen was estimated to be 4,500 with the formula C302H440O23N6S2. The fractions of aromatic, naphthenic, and paraffinic carbon of the kerogen were assessed as 0.30, 0.21, and 0.49, respectively. A sketch of kerogen carbon skeleton was also discussed.