Formation kinetics, mechanism of CO2 hydrate and its applications

Carbon dioxide (CO2) hydrate technology has the potential applications to the fields of CO2 capture and storage, gas replacement in the exploitation of natural gas hydrates, seawater desalination and refrigeration. These applications can provide the alternative solutions to the problems presented in the fields of climate and energy. Therefore, this review detailly discusses the basic researches of CO2 hydrate nucleation and growth as well as the potential applications of CO2 hydrate technology. Firstly, CO2 hydrate nucleation and growth were analyzed in the absence of additives. The kinetics of CO2 hydrate formation is mainly affected by pressure, temperature and stirring speed, etc. Then, the effects of different additives on kinetics of CO2 hydrate formation are discussed due to the structural groups of additives, concentrations of additives and driving force. In addition, CO2 hydrate nucleation can be promoted or inhibited by the enhancement or disruption of local hydrogen-bonding network between water molecules. CO2 hydrate growth can be promoted or inhibited by accelerating or limiting CO2 molecules and water molecules to reach the growth site. Moreover, some kinetic models are constructed based on the basic theory and mechanism to describe the process of CO2 hydrate formation. Experimental studies and large-scale field tests illustrate that the industrial applications of CO2 hydrate technology are promising. More comprehensive and systematic studies including the further environmental impact and economic benefits still need to be done in the future.