Mechanistic Insights into CO2 Sequestration via Clathrate Hydrate Formation from Molecular Simulations: Influence of Temperature and Pressure

作者：Yukun Shen, Qiang Shen, Yi Jin, Zhongjin He · 发表于：Energy & Fuels · 年份：2025 · DOI：10.1021/acs.energyfuels.5c00682 · 被引用次数：11 · 研究领域：Methane Hydrates and Related Phenomena、CO2 Sequestration and Geologic Interactions、Atmospheric and Environmental Gas Dynamics

Complex temperature/pressure conditions are present in the process of CO 2 sequestration in hydrate form in subsea sediments; how temperature and pressure affect CO 2 hydrate formation remains unclear. To address this issue, molecular dynamics simulations were conducted to explore CO 2 hydrate formation in a CO 2 /water two-phase system under a series of temperature/pressure conditions, i.e., 250, 255, 260, 263, 265, 268, 270, and 273 K (all at 50 MPa) and 5, 10, 20, 30, 40, and 50 MPa (all at 250 K). Simulation results show that CO 2 hydrate formation is more sensitive to the change in temperature than to pressure: Hydrate forms only at 250 K and 50, 40, 30, and 20 MPa, but not at higher temperatures. CO 2 hydrate formation is closely related with the evolution of CO 2 hydration shells, where hydrogen bond formation is the predominant reaction. Adsorption of sufficient CO 2 molecules to the CO 2 hydration shells significantly prolongs the lifetimes of hydrogen bonds and is crucial to cage formation and hydrate nucleation. Such a formation mechanism of CO 2 hydrate is identified in the nucleated systems. Pressure and temperature affect the formation of CO 2 hydrate via directly impacting the stability of hydrogen bonds in the CO 2 hydration shells. Furthermore, pressure and temperature indirectly influence the stability of hydrogen bonds via changing the concentration of CO 2 in water, which could modulate the number of CO 2 molecules adsorbing to the CO 2 hydration shells an...