Ethane Forms Molecular Clusters Under Nanoconfinement

The phase behavior of light hydrocarbons under nanoconfined is key to estimating natural gas reserves and it represents a crucial knowledge gap in designing of separation membranes for petrochemical processes. Under nanoconfinement, the combined energetic and entropic effects due to the presence of solid interfaces lead to enhanced density and shift the phase envelope of fluids. In this work, we employ molecular simulations to investigate the phase behavior and microscopic structure of nanoconfined ethane. Clustering analysis of the atomistic trajectories shows that molecular clusters, i.e., groupings of ethane molecules, form inside cylindrical silica nanopores with diameters between 1 and 20 nm. The size and topology of these clusters depend on the thermodynamic conditions of the fluid, including the temperature and the centerline density. We suggest that the molecular clusters strongly influence the thermodiffusive properties of the nanoconfined fluid.