Solubility and Separation Mechanism of R410A in Ionic Liquids: Constant Chemical Potential Molecular Dynamics Simulations

In this work, constant chemical potential molecular dynamics was employed to investigate the dissolution characteristics of difluoromethane (R32), pentafluoroethane (R125), and R410A (50 wt % R32 and 50 wt % R125) in 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) ionic liquids (ILs). Simulated solubilities of R32, R125, and their equimolar mixtures agreed well with the literature data. The solubility, self-diffusion, and separation selectivity of R410A in [BMIM][PF6] and [BMIM][BF4] were further predicted from 283.15 to 323.15 K and 0.25 MPa to 0.85 MPa. The results show that the ternary selectivity is consistently higher than that estimated from binary solubilities. Meanwhile, R32 has a significantly higher self-diffusion coefficient than that of R125. Radial distribution function (RDF) and interaction energy analyses were carried out to explain the separation mechanisms. This research elucidates the competitive dissolution mechanism at the molecular level, providing a theoretical foundation for designing ILs for azeotropic or near-azeotropic refrigerant separations.