Study on Carbon Storage by CO<sub>2</sub> Hydrate Formation in the Ion-Containing Environment

Abstract

The current greenhouse effect caused by massive CO₂ accumulation must be addressed urgently. Because of the ocean's enormous capacity, the high density of CO₂ hydrate, and the high stability of CO₂ sequestration in hydrate form, the process of hydrate generation can trap CO₂ molecules into the lattice of water molecules and is considered for the sequestration of CO₂ in hydrate form in the ocean. In this paper, molecular dynamics (MD) simulations are used to investigate the kinetic behavior of CO₂ hydrate growth in ion-containing electrolyte solutions. The mechanism of salt ion effect on hydrate growth during pressure changes is investigated. The simulations show that in the presence of salt ions, the hydrate growth rate fluctuates significantly, despite the fact that a greater driving force can facilitate the hydrate growth process. Higher pressures increase guest molecule occupancy in the hydrate cage, while the saline environment causes competition for water molecules between the hydrate cage and salt ions, increasing the proportion of empty cages. Lower pressures and the presence of salt ions reduce CO₂ molecules' selectivity for the smaller 5¹² cages, creating a barrier to hydrate growth. The findings of the study look at the microscopic mechanism of CO₂ hydrate generation in seawater and serve as a guide for future implementation of hydrate method CO₂ sequestration technology in the marine environment.