Study on the kinetic characteristics of CO2 hydrate formation in a pure water system

Hydrate-based carbon dioxide sequestration presents a promising strategy for mitigating anthropogenic greenhouse gas emissions. Understanding the formation dynamics of CO 2 hydrates in aqueous systems is critical for optimizing hydrate-based storage technology. This study demonstrates the interfacial nucleation and staged growth mechanisms of CO 2 hydrates in pure water under isobaric conditions (3 MPa, 6 °C). The mechanisms are elucidated using real-time kinetic and thermodynamic analyses. Experimental results reveal that hydrate formation initiates preferentially at the gas–liquid interface and subsequently evolves into porous honeycomb-structured aggregates through three sequential phases: dissolution-dominated gas-liquid mass transfer, a metastable induction/nucleation stage with an extended induction time of 214 min, and rapid hydrate growth at 0.025 mol·min −1 . The process achieves a CO 2 -to-hydrate conversion efficiency of 67.3%, storing 10.61 L of CO 2 per liter of water with a hydrate volume fraction of 6.12%. These findings highlight the critical role of interfacial dynamics in hydrate crystallization and establish the technical viability of moderate subcooling strategies for energy-efficient carbon sequestration, providing fundamental insights for optimizing hydrate-based carbon capture and storage technologies. • The constant pressure method was adopted to study the formation of CO 2 hydrates. • The different stages of CO 2 hydrate formation were analyzed. • The hydrates ultimately evolve into a "honeycomb-like" aggregate of hydrates. • At a pressure of 3 MPa and a temperature of 6°C, the induction time is 214 min.