Thermal Dissolution and Hydrogenation of Mixture of Coal and Oil Shale
Abstract
Recently, researchers have paid much attention to the study of the processes involved in the simultaneous thermocatalytic processing of oil shale and brown coal. This is particularly relevant for the Kenderlyk, Mamyt, Shubarkol, Taldykol, and Kiyin deposits in the Re-public of Kazakhstan, where both brown coal and shale are present. This work presents findings from a study on the thermal decomposition, thermal dissolution, and hydrogenation of coal and shale. The peak of the main organic matter (OM) decomposition in shale occurs at lower temperatures compared to that in coal. Hydrogenation of a coal-shale mixture in a 35:15 ratio with a nickel catalyst significantly enhances the yield of liquid products from the organic mass of the feedstock to 87.9 wt.% and reduces gas formation to 7.5 wt.%. Substituting tar with an oil-based paste-forming agent also significantly improves the hydrogenation performance of coal and shale mixtures. With a shale-to-coal ratio of 40:10, the yield of liquid products increases from 71.5 to 74.7 wt.%. The produced fuel products were analyzed using gas chromatography and elemental analysis. The resulting gasoline fraction contains a high proportion of paraffin-naphthenic hydrocarbons (73.5 wt.%) and a moderate amount of aromatic hydrocarbons (26.5 wt.%), along with nitrogenous bases (1.5 vol.%) and phenols (2.7 vol.%). Based on these experimental results, a schematic diagram of an improved process for producing motor fuel and chemical products through the hydrogenation of a mixture of coal and oil shale under low pressure has been developed. Studies have shown that the organic and mineral components of oil shale have an activating effect on the thermocatalytic conversion of brown coal, heavy residual oil products, and liquid high-boiling waste from some petrochemical industries.