Experiments and thermodynamic simulations for continuous separation of CO₂ from CH₄+CO₂ gas mixture utilizing hydrate formation

In this paper, we experimentally investigated the time evolution of compositions in the gas phase and the hydrate slurry during long-term operations of hydrate-based CO₂ separation. We performed continuous gas separation experiments at pressure of 2.3MPa and temperature of 273.2K. We continually analyzed the compositions in the gas phase and the hydrate slurry formed from CH₄+CO₂ gas mixture (CH₄:CO₂=0.40:0.60). We also carried out thermodynamic simulations under the same conditions to confirm the reliability of thermodynamic simulations for hydrate-based CO₂ separation. We experimentally succeeded in separating CO₂ from CH₄+CO₂ gas mixture and understanding the time evolutions of compositions in the gas phase and the hydrate slurry. The compositions in the gas phase and the hydrate slurry reached a steady state in 15h. The composition of CH₄ in the gas phase and that of CO₂ in the hydrate slurry reached 0.61 and 0.76 at the steady state, respectively. The deviations of the compositions in the gas phase and the hydrate slurry between the continuous gas separation experiments and thermodynamic simulations are 0.01 and 0.02, respectively. These results demonstrated that long-term operations of hydrate-based CO₂ separation can be put into practice and support the reliability of thermodynamic simulations for hydrate-based CO₂ separation.