Unraveling the Role of Amino Acid L -Tryptophan Concentration in Enhancing CO 2 Hydrate Kinetics

Carbon dioxide (CO 2 ) hydrates have garnered significant interest as a promising technology for CO 2 capture and storage due to its high storage capacity and moderate operating conditions. The kinetics of CO 2 hydrate formation is a critical factor in determining the feasibility of hydrate-based CO 2 capture and storage technologies. This study systematically investigates the promotional effects of the amino acid L -tryptophan ( L -trp) on CO 2 hydrate formation kinetics and morphology under stirred and unstirred conditions. In the stirred system, experiments were conducted in a high-pressure 100 mL reactor with 0.05, 0.10, and 0.30 wt% L -trp solution. CO 2 gas uptake kinetics and morphological evolution were monitored using a high-resolution digital camera. Results showed that L -trp promoted CO 2 hydrate formation kinetics without delay, with rapid CO 2 consumption upon nucleation. Morphological evolution revealed rapid hydrate formation, wall-climbing growth, and dendritic morphology filling the bulk solution. Under unstirred conditions, experiments were performed in a larger 1 L reactor with 0.1 wt% and 0.5 wt% L -trp solutions to assess the influence of additive concentration on hydrate formation thermodynamics and kinetics. Results demonstrated that L -trp influenced both thermodynamics and kinetics of CO 2 hydrate formation. Thermodynamically, 0.1 wt% L -trp resulted in the highest hydrate formation, indicating an optimal concentration for thermodynamic promotion. Kinetically, increasing L -trp concentration from 0.1 wt% to 0.5 wt% reduced formation time, demonstrating a proportional relationship between L -trp concentration and formation kinetics. These findings provide insights into the role of L -trp in promoting CO 2 hydrate formation and the interplay between additive concentration, thermodynamics, and kinetics. The results can inform the development of effective hydrate-based technologies for CO 2 sequestration, highlighting the potential of amino acids as promoters in gas hydrate.