Promoting Effect of Common Marine Cations on Hydrate Dissociation and Structural Evolution under a Static Electric Field

• Main Authors: Bingbing Chen (1742596), Kehan Li (413697), Huiru Sun (4269175), Lanlan Jiang (1917829), Mingjun Yang (1358769), Yongchen Song (1358772)
• Format: Dataset
• Language: unknown
• Published: 2023
• Subjects: Biochemistry; Biotechnology; Ecology; Inorganic Chemistry; Chemical Sciences not elsewhere classified; Physical Sciences not elsewhere classified; random semiopen cages; potential energy resource; molecular dynamics simulations; ion current occurred; free energy indicates; called ion migration; attracting worldwide attention; 2 +</ sup; hydrate structures formed; gas hydrate using; sup >+</ sup; common marine cations; gas hydrate dissociation; gas hydrate; hydrate dissociation; methane hydrate; hydrate phase; ≈ na; ≈ mg; uses seawater; thermodynamic properties; structural evolution; structural changes; se method; salt solutions; results show; promotion effect; promoting effect; new method; multiple kinds; monovalent cations; mh dissociation; kinetic properties; key issue; essentially temporary; electrostatic fields; electrostatic field; electric field; drive cations; divalent cations; Methane hydrate
• Online Access: https://doi.org/10.1021/acs.jpcb.2c05382.s002

Natural gas hydrate, a potential energy resource, is attracting worldwide attention. In this study, we propose a new method of hydrate dissociation which uses seawater and electrostatic fields (SE method) cooperatively. The hydrate molecular dissociation mechanism of gas hydrate is a key issue in studying the kinetic properties of gas hydrate using the SE method. Therefore, molecular dynamics simulations were used to investigate the thermodynamic properties and structural changes of methane hydrate (MH) in multiple kinds of salt solutions under an electrostatic field. The results show that the electric field can drive cations into the MH phase to form a series of random semiopen cages, which are essentially temporary and metastable. The variation in free energy indicates that it is more difficult for divalent cations to enter the hydrate phase than monovalent cations, meaning that the hydrate structures formed with divalent cations are more unstable. Then, the ion current occurred in the hydrate phase (called ion migration in this study), which greatly accelerated hydrate dissociation. In contrast, the promotion effect of cations with the same charge on MH dissociation is as follows: Sr 2+ > K + ≈ Na + > Ca 2+ ≈ Mg 2+ . In general, the presence of common marine cations enhanced the promotion effect of the electric field on gas hydrate dissociation.