Absorption of CO2 by Tetra‑n‑Butylammonium Bromide Semiclathrate Hydrate Slurries in a Bubble Column with Temperature Swing

Hydrate-based carbon capture technology offers simple operation and adaptation to small-scale regional biomass systems. Absorption of CO2 by tetra-n-butylammonium bromide semiclathrate hydrate (SCH) slurries was investigated with a temperature-swing bubble column to elucidate clathrate formation mechanisms. At a constant temperature (278 K), the amount of CO2 absorbed into the hydrate phase was 0.43 mmol-CO2/mol-H2O at 0.15 MPa CO2 partial pressure. When the temperature was lowered to 276 K and held constant for 30 min, the amount of CO2 absorbed increased (1.25 mmol-CO2/mol-H2O). When the temperature was raised to 278 K and held constant for 30 min, the amount of CO2 absorbed decreased (1.08 mmol-CO2/mol-H2O), which was attributed to preferential decomposition of SCH with low CO2 occupancy, because these particles have low thermodynamic stability. CO2 absorption capacity in SCH slurries in bubble columns can be doubled by temperature swing since SCH dynamic formation with CO2 absorption is faster than CO2 absorption in existing SCH.