A Comprehensive Review on the Rapid Hydrate Formation for CO₂ Capture: Characteristics, Mechanism, and Applications

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CO 2 , being a major greenhouse gas, is regarded as an important contributor to global warming and environmental problems. CO 2 capture and separation are an efficient approach for reducing CO 2 emissions in the atmosphere. A hydrate method of CO 2 capture and separation provides a feasible solution to the emission reduction of CO 2 in the atmosphere. However, the rapid formation of hydrate is crucial for CO 2 capture and separation using the hydrate technique. As a consequence, this paper comprehensively reviewed the rapid formation characteristics and the kinetic law of CO 2 hydrate, as well as deeply analyzed the influences of temperature and pressure conditions, gas–liquid ratios, additives, hydration reaction system, hydration reaction process, and other factors on its formation process. On this basis, the quantitative impact and regulatory mechanisms of different factors on the nucleation and growth process of CO 2 hydrate were comprehensively analyzed. The influence mechanisms and kinetic laws of temperature, pressure, gas–liquid ratio selection, additive concentration, and type of reaction system on CO 2 hydrate rapid formation were detailed. The regulatory and enhancement mechanisms of CO 2 hydrate rapid formation under multiple factors were elucidated. The application of CO 2 capture by the hydrate method and its challenges are summarized. In the end, the key problems and future directions of rapid CO 2 capture and separation using the hydrate method were pointed out. The synergistic mechanism of rapid CO 2 hydrate formation and the enhancement through multiple factors still need to be further investigated. Developing new reactor structures and optimizing the hydration reaction process are important in promoting the rapid formation of CO 2 hydrate.