Molecular simulation of fluid adsorption in nanoporous adsorbents: simple descriptors for space decontamination applications

We report a molecular simulation study on the adsorption-based trapping of different gaseous contaminants using nanoporous materials. In more detail, in the context of gas decontamination for space applications, we focus on adsorption from low pressures up to larger pressures of specific molecules ranging from water, hydrocarbons, and siloxanes. As far as the nanoporous adsorbents are concerned, we restrict the present study to a set of prototypical materials: an active carbon, a zeolite and a metal-organic framework. In addition to discussing the ability of each material type to adsorb specific gas molecules, we illustrate how simple descriptors such as Henry’s constant in the low-pressure range \(K_\text {H}\) and the pressure \(\alpha\) at which half the nanoporosity gets filled can be used to rationalize and design molecular “getters” for space decontamination. Finally, by considering a specific yet representative binary gas mixture, we show that the adsorption of hydrophilic molecules– water– and hydrophobic molecules– siloxane– occurs without competitive/collective adsorption effect (provided adsorption occurs at low to moderate pressures).