INVESTIGATION OF CH4 - CO2 GAS MIXTURE SOLUBILITY IN TETRAHYDROFURAN - SODIUM DODECYL SULFATE AQUEOUS SOLUTIONS

Vapor-liquid equilibrium data for the methane (CH4) (81.70 %mol) and carbon dioxide (CO2) (18.30 %mol) gas mixture with adding aqueous solutions of 3.80 %wt tetrahydrofuran (THF) and 0.30 %wt sodium dodecyl sulfate (SDS) were experimentally determined. The experimental temperatures were 283.15 and 293.15 K. The equilibrium pressures were in the range 0.60-5.04 MPa. It was found that the CH4 solubility in the aqueous solutions is approximately one order of magnitude lower than the CO2 solubility. The experimental data of the gas mixture solubility in the aqueous solutions were compared with the simulation results in Aspen Plus V10. The most adequate agreement between the experimental and thermodynamic simulation data of the CO2 solubility in the CH4 (81.70 %mol) - CO2 (18.30 %mol) gas mixture in the H2O and H2O - THF (3.80 %wt) solutions was observed using the UNIQUAC and UNIFAC methods, respectively. The average relative uncertainties of these methods were 4.18 and 1.81%. In the case of the H2O - SDS (0.30 %wt) and H2O - THF (3.80 %wt) - SDS (0.30 %wt) solutions, the most suitable methods applied were Non-random two-liquid/Wilson (NRTL/Wilson) and Non-random two-liquid - Redlich-Kwong (NRTL-RK) methods, respectively (the relative uncertainties were equal). The average relative uncertainties of these methods were 7.38 and 9.30%. The obtained results will be applied for natural gas purification from CO2 using the gas hydrate crystallization technology.

Automated summary

This study experimentally determined the vapor-liquid equilibrium data for a gas mixture of methane and carbon dioxide with different aqueous solutions, and compared the results with simulation data. It was found that methane has a lower solubility in the aqueous solutions compared to carbon dioxide. The most suitable methods for calculating the solubility of carbon dioxide in different solutions were determined based on the experimental data and simulation results. These findings are important for the purification of natural gas from carbon dioxide using gas hydrate crystallization technology.