Efficient hydrate-based carbon capture system enabled by red blood cell inspired encapsulation

Encapsulation is an effective method to improve gas-liquid mass transfer and accelerate gas hydrate formation kinetics. However, the utilisation of encapsulation in the hydrate-based carbon capture (HBCC) system has never been implemented. In this work, an efficient HBCC unit based on the red-blood-cell (RBC) inspired encapsulation was designed for the first time, and its carbon capture performance were experimentally investigated. A validated numerical model was developed to investigate the impact of capsule layouts and capsule size on hydrate formation kinetics. Furthermore, we proposed a close-packing configuration of RBC capsules based on the natural structure of beehives, in which the space utilisation rate of capsules can achieve 64.3%. The CO2 capture performance of this configuration was examined in both a closed system and an open system under different pressures. For a closed system, a trade-off between water-to-hydrate conversion rate and average CO2 uptake per space volume was observed. The highest attainable water-to-hydrate conversion rate, reaching 88.5%, is realized at an initial pressure of 4.5 MPa, concomitant with an average CO2 uptake per unit space volume of 6.12 mol min−1 m−3. For an open system, both high water-to-hydrate conversion rate and CO2 uptake efficiency per unit volume can be achieved even at low operating pressures.