Chemical Characterization of Organic Compounds in Leachates from Surface-Retorted Oil Shale Generated by Gas Combustion and Indirect Pyrolysis

Abstract

Chemical characterization of leachates from surface-retorted oil shale generated by gas combustion (Paraho process) and indirectly-heated pyrolysis (TOSCO II process) revealed the presence of several classes of organic acids. Paraho leachates contained various oxygenated species, such as aliphatic monocarboxylic acids (C₅-C₈), dicarboxylic acids (C₈-C₁₁), and arenecarboxylic acids, with benzoic acid as the major component. A series of methyl-substituted arenecarboxylic acids were identified in the TOSCO leachate, with 3,5-dimethylbenzoic acid as the major component. Differences in chemical composition of the two leachates can be explained in terms of the different processes used to generate the two types of spent shale. Arenecarboxylic acids in both leachates were quantitatively determined. The potential exists for leaching of these oxygenated species from spent shale.

Key Words:

• Gas chromatography-mass spectrometry
• arenecarboxylic acids
• oil shale.