Coupling Amino Acid with THF for the Synergistic Promotion of CO2 Hydrate Micro Kinetics: Implication for Hydrate-Based CO2 Sequestration

CO 2 capture and sequestration are broadly recognized as the most effective technology for reducing CO 2 emissions and mitigating global climate change. In this regard, hydrate-based CO 2 sequestration (HBCS) has been proposed as an effective method for long-term safe and stable CO 2 sequestration. It is a promising technology for reducing the concentration of CO 2 in the atmosphere and achieving carbon neutrality. However, one major challenge related to HBCS technology is the lack of understanding of how to improve the formation kinetics of CO 2 hydrate effectively. Herein, in this study, we identified the synergistic promotion effect on CO 2 hydrate formation when a low-dose thermodynamic promoter (tetrahydrofuran, THF) is coupled with an environment-friendly kinetic promoter ( l -methionine, l -Met). Based on the kinetic experiments and the morphological observation, 0.6 mol % THF coupled with 0.1 wt % l -Met yields the optimal CO 2 gas uptake. In situ Raman spectra reveal the mechanism of the observed two-step growth behavior at the molecular level, where low-dose THF promotes the initial CO 2 -THF sII hydrate nucleation and growth in the solution and l -Met promotes the subsequent CO 2 sI hydrate growth along the surface of the reactor. Our study unveils the underlying synergistic mechanism when thermodynamic and kinetic promoters are coupled for CO 2 hydrate formation. The results provide guidance for the identification and use of novel bio-friendly thermodynamic and kinetic promoters and are beneficial to a series of sustainable hydrate-based technologies when fast CO 2 formation is required.