Amino Acids Based CO₂/N₂ Capture and Storage under High Pressure & Low Temperature Geological Conditions

Geological sequestration of CO2-rich gas as a CO2 capture and storage technology has a lower technical and cost barrier compared to industrial scale-up. In this study, we proposed CO2 capture and storage via hydrates in geological formations within the hydrate stability zone as a novel technique to contribute to global warming mitigation strategies, including carbon capture, utilization, and storage (CCUS), and to prevent large methane release to the atmosphere caused by hydrate melting.
A trapping mechanism via the CO2 hydrate layer at the base of the gas hydrate stability zone can be used to prevent upward migration of CO2 for long-term storage. CO2 capture and sequestration into the geological formation within the hydrate stability zone can be enhanced in the presence of hydrate promoters, including surfactants and amino acids.
Improved formation kinetics are observed in the presence of surfactants (1000-3000 ppm) and hydrophobic amino acids (3000 ppm) at 120 bar and 1 °C experimental conditions. We report an induction time in the range of 7-170 min and a CO2 split fraction (0.60-0.90) in the hydrate for 120 bar initial injection pressure. The CO2 split fraction can be improved by reducing the sand particle size or increasing the CO2 mole percent in the incoming feed gas for a given injection pressure. The injection pressure requirements for CO2 gas hydrate formation (CGHF) are too high to be implemented on an industrial scale. Therefore, hydrophobic amino acids as kinetic promoters together with thermodynamic promoters such as THF and tetra-n-butylammonium bromide (TBAB) could enable a more environmentally friendly solution for CO2 capture via CGHF with modest operational requirements.