Research progress of molecular dynamics simulation on the formation-decomposition mechanism and stability of CO2 hydrate in porous media: A review

The technique of hydrate-based CO2 storage in sediments is an alternative option to mitigate global warming and reduce CO2 emissions. The formation-decomposition mechanism and stability of hydrate is the fundamental issue to illuminate the storage characteristic. In this review, we present a comprehensive overview on the progress of molecular dynamics (MD) simulation on the formation-decomposition mechanism and stability of hydrate in porous media. The microscopic mechanism of CO2 hydrate formation and decomposition is analyzed and summarized according to the superiority of MD simulation in predicting hydrate formation and decomposition. The elementary properties, microstructure and phase equilibrium characteristic of CO2 hydrate are systematically summarized. Various key factors affecting the formation and decomposition of CO2 hydrate are illustrated, including the porous media, additives and so on. Meanwhile, the decomposition characteristic and stability of CO2 hydrate was comprehensively reviewed. More importantly, the effects of porous media and additives on the formation and decomposition characteristics are also summarized. Knowledge gap still exists in understanding the formation-decomposition mechanism of CO2 hydrate in porous media, which is further augmented by the MD simulation. In addition, based on the current research, some drawbacks and limitations of MD simulation referring to the formation-decomposition and stability of CO2 hydrate are further discussed. This review summarizes the progress of MD simulation on hydrate formation and decomposition in recent years and provides valuable guidance for commercial CO2 capture and storage in sediments in the future.