Understanding the effects of preadsorbed perfluoroalkanes on the adsorption of water and ammonia in MOFs

The effects of preadsorbed perfluoroalkanes on water and ammonia adsorption in a well-known metal-organic framework, Cu-BTC, were investigated using molecular simulations. It was found that perfluoroalkane molecules have little effect on water or ammonia adsorption in the Henry region. At higher loading, an analysis of the hydrogen bonds for water revealed that the presence of perfluoroalkanes reduces water clustering inside Cu-BTC. However, despite the expected hydrophobicity of perfluoroalkanes, their presence was not found to induce a more hydrophobic behavior in Cu-BTC, and the water condensation step was not significantly shifted. Ammonia uptake in Cu-BTC was not enhanced by perfluoroalkanes under dry or humid conditions.