Experimental and theoretical studies on kinetics for thermochemical sulfate reduction of oil, C2-5 and methane

Publication date: Available online 14 January 2019Source: Journal of Analytical and Applied PyrolysisAuthor(s): Kun He, Shuichang Zhang, Jingkui Mi, Qisheng Ma, Yongchun Tang, Yu FangAbstractTo address the kinetic parameters for thermochemical sulfate reduction (TSR) of oil and hydrocarbon gases, hydrothermal experiments involving oil or methane and sulfate at 50 MPa were conducted by a gold tube pyrolysis system. By determination of gas yields in non-isothermal pyrolysis of oil with gypsum and water, it was found that the generation of H2S can be divided into two stages, including TSR of liquid oil and C2-5 hydrocarbon gases. The average activation energies (Ea) for TSR of oil and C2-5 were fitted to be 58.1 and 65.9 kcal/mol, respectively. By isothermal pyrolysis of methane-dominated gas with aqueous MgSO4 at 500˜600 °C, the reaction rates for TSR of methane at elevated temperature was determined. Meanwhile, theoretical calculations based on density functional theory (DFT) and transition state (TS) were carried out to obtain the thermodynamic parameters for the oxidation of methane by different sulfate species. It is revealed that the energy barriers for reactions between methane and HSO4- or [MgSO4]CIP at 0˜600 °C were much lower than those for free SO42-. Combined the experimental results and theoretical calculations, the Ea for TSR of methane involving SO42-, HSO4- and [MgSO4]CIP were calculated to be 67.0, 52.1 and 54.9 kcal/mol, respectively. Finally, the...

Source: Journal of Analytical and Applied Pyrolysis - January 15, 2019 Category: Chemistry Source Type: research