The controlled release of CO2 from structure I (sI) hydrates is essential for advancing carbon capture and storage (CCS) technologies. This study utilizes molecular dynamics (MD) simulations to investigate the pressure-dependent (1-80 bar) dissociation of CO2 hydrates in two aqueous deep eutectic solvents (DESs) medium: tetrabutylammonium bromide/ethylene glycol (TBAB/EG, DES1) and methyl triphenyl phosphonium bromide/ethylene glycol (MTPB/EG, DES2), each in a 1:4 M ratio. The results demonstrate that both pressure and DES composition critically influence hydrate stability. DES1 promotes greater CO2 release by reducing the CO2 density from 640 kg/m3 within the sI hydrate to 206 kg/m3 at the sI hydrate-aqueous DES1 interface at 80 bar. DES1 shows more hydrogen bonding between CO2 and aqueous water, while enhancing CO2 mobility, outperforming DES2. The radial distribution function (RDF) analysis shows that CO2 interacts more strongly with aqueous water in the presence of DES1, with a coordination number (CN) of approximately 27.02 at 1 bar, compared to DES2, which shows a maximum CN of about 26.37 at 1 bar. Higher CO2 mobility in the aqueous DES1 phase from CO2 hydrate is further supported by mean square displacement (MSD) compared to DES2. These findings establish a molecular-level framework for understanding how DES composition modulates hydrate dissociation, offering valuable insights for the rational design of DES-based media for targeted CO2 sequestration.
Shastri et al. (Fri,) studied this question.