Understanding Water Adsorption in Cu-BTC Metal-Organic Frameworks

Molecular simulations were performed to study the adsorption behavior of water in the metal-organic framework Cu-BTC. This is one of the better-known materials of this type that is stable upon water adsorption/desorption. The charge of the framework atoms was fitted to reproduce the available experimental adsorption isotherm. This new set of interaction parameters was used to calculate Henry coefficients as well as the energies, entropies, and enthalpies for the different adsorption sites. Our simulations show that water has a surprisingly large affinity for the metal center in Cu-BTC compared to other that for molecules like carbon dioxide, nitrogen, oxygen, or hydrocarbons. This particular behavior could be further exploited for the separation of water from other compounds.