Non-isothermal conversion of the Kashpir sulfur-rich oil shale in a supercritical water flow

• Conversion of sulfur-rich oil shale in a flow of water vapor and SCW under non-isothermal conditions has been studied.
• The maximum yield of the liquid products is observed at 360–390 °C.
• The liquid products are characterized by a high content of thiophene and thiophenol derivatives.
• As a result of the thermolysis of organic sulfides and the reaction of FeS2 with H2O, the degree of oil shale desulfurization excesses 60 wt%.

The conversion of the Kashpir oil shale (gross-formula CH1.48N0.01S0.10O0.24) in a flow of water vapor and supercritical water at uniform increase in temperature (dT/dt = 1 °C/min) from 300 to 550 °C has been studied. Temperature dependences of the yields of the volatile and liquid products and their component and elemental compositions have been determined. The total yields of the volatile and liquid products and the conversion residue formed during the experiment have been found to be equal to 404.8, 383.8, and 543.0 mg/gC, respectively. The maximum yield of the volatile products, containing H2S, CO2, H2, and CH4 as major components, is observed at 300–360 °C. A high yield of these compounds is brought about by the redox reactions of oil shale organic matter and mineral components with water. The maximum yield of the liquid products is observed at 360–390 °C, the oil fraction in their composition increasing from 57% to 78% along with increase in temperature. The composition of the liquid products is defined by means of IR and 1H NMR spectroscopy. A new approach to the problem of the Kashpir oil shale processing in SCW in order to obtain the desired S-containing products is discussed.

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