Formation and Decomposition Kinetics of CO ₂ Hydrates under Static and Stirred Conditions

In the context of global climate change and energy transition strategies, the CO2 hydrate technology has emerged as a promising solution in carbon sequestration and energy storage. This study systematically examines the formation and dissociation kinetics of CO2 hydrates in pure water systems using a high-pressure reactor under both static and stirred conditions. Key experimental observations reveal distinct phase behavior: under static conditions, a continuous CO2 hydrate membrane with no obvious macroscopic pores is formed, with no visible bubble penetration or membrane surface damage observed, creating significant mass transfer barriers, while the introduction of a gas–liquid phase connecting tube promotes both membrane thickening and bulk hydrate formation. In contrast, stirred systems generate dispersed hydrate particles that exhibit either slurry-type or crystalline morphology. Kinetic analysis shows that, under identical conditions, the hydrate formation conversion rate of stirred systems is twice that of static systems, significantly improving the formation efficiency, and finally, its formation amount is nearly twice that of static systems. For dissociation kinetics, the decomposition rate of stirred systems is twice that of static systems under the same decomposition temperature. At the same decomposition pressure, the decomposition rate of the stirred system is 5 times that of the static system. Dissociation characteristics differ markedly between systems. Static conditions produce membrane sedimentation, while stirred systems show bubble-induced optical clearing. The driving force of static system shows the characteristics of “first rising and then stabilizing at a high level”, while the driving force of the stirred system shows the dynamic characteristics of “sudden rise and decay to stability” and finally achieves system balance. These findings offer valuable insights for advancing CO2-hydrate-based technologies in energy and environmental applications.