Continuous CO₂ Separation from a N₂ + CO₂ Gas Mixture Using Clathrate Hydrate: Insights into Sustainable Post-combustion Carbon Capture

Abstract

Clathrate-hydrate-based CO2 capture from a post-combustion N2 + CO2 gas mixture has been experimentally investigated for decarbonization. In this study, we performed hydrate-based continuous CO2 separation experiments for N2 + CO2 + tetrahydropyran (THP) + water system. The experimental conditions were set at 280.1 K under 3.0 MPa with THP mass fractions w THP of 0.22 and 0.11. For each experimental run, the time-dependent changes in compositions in the gas phase and the hydrate slurry were recorded hourly until the system reached a steady state. The cage occupancies of N2 and CO2 in the structure II 512 small cages were determined to be 43 and 24%, respectively, with the powder X-ray diffraction analysis. The obtained results showed that the continuous carbon capture is a practicable scheme, yet the CO2 concentration rate and CO2 recovery ratio are comparable to or lower than those of the pre-combustion systems reported in previous studies. Still, our investigation revealed that the development of an efficient hydrate formation method, such as the improvement of the geometry of mixing impellers, could enhance the CO2 recovery ratio for the continuous operation.

Renewed Measurements of Carbon Dioxide Hydrate Phase Equilibrium

“…Fitting parameters for Equation(2) and the correlation coefficient Figure8shows the scatter of the three-phase equilibrium conditions in carbon dioxide + water system measured in this study with those reported in the previous studies. From this figure, we evaluated the even more precise external consistency of the measured data in this study with the data from the previous studies.…”

“…From this figure, we evaluated the even more precise external consistency of the measured data in this study with the data from the previous studies. pcalc is calculated with the interpolation of the three-phase equilibrium condition data measured in this study by using Equation(2). Dot line represents twice the uncertainty of the pressure measurement in this study.…”

2022 Pioneers in Energy Research: John Ripmeester

“…Gas hydrates could be used as a molecular sieve, whereby depending upon the shape and size of the hydrate-forming guests, one of the gases from a gas mixture may preferentially occupy the solid hydrate cages and become separated from its mixture. 41 A mini review by Wu et al 42 summarized the stateof-the art research work performed for hydrate-based gas separation for CO 2 capture from CO 2 /CH 4 gas mixtures. A bench-scale dual-bed cyclic gas hydrate process (DB-CGHP) for separation of gas mixtures was presented, and potential for industrial scale-up similar to a pressure swing adsorption process was demonstrated.…”

“…A review by Rodionova et al discussed structures of single and double ionic clathrate hydrates (semi-clathrates) in the presence of different gases and possibilities of structural transition as a result of the presence of these gases. Gas hydrates could be used as a molecular sieve, whereby depending upon the shape and size of the hydrate-forming guests, one of the gases from a gas mixture may preferentially occupy the solid hydrate cages and become separated from its mixture . A mini review by Wu et al summarized the state-of-the art research work performed for hydrate-based gas separation for CO 2 capture from CO 2 /CH 4 gas mixtures.…”

Thermally Induced Phase Transition of Cubic Structure II Hydrate: Crystal Structures of Tetrahydropyran–CO2 Binary Hydrate

“…CO 2 also forms binary sII and sH hydrates under milder pressure and temperature conditions than pure CO 2 hydrate (1.2 MPa at 273 K) with the assistance of larger guest molecules, such as tetrahydrofuran (THF: C 4 H 8 O) and cyclopentane (CP: C 5 H 10 ). The large guests are encaged into the larger cages of the sII phase (H or 5 12 6 4 cages), and the CO 2 is encaged into the small D cages. − Binary hydrates with THF, CP, , and tetrahydropyran (THP: C 5 H 10 O) , large guests have been studied as media to store gases such as H 2 , CH 4 , and CO 2 in their empty D cages. However, relatively little is known about the effect of these large guest molecules or synergistic effects between large and small guest molecules on the crystal structure and physical properties of clathrate hydrates under different temperature and pressure conditions.…”