A Review on Adsorption\nin Nanoporous Adsorbents for\nGas Decontamination: Space Applications and Beyond

This technical report presents the state of the art of\nexperiments\nand molecular simulations on the adsorption of different molecule\ntypes into nanoporous adsorbents in the context of gas decontamination.\nWhile this review is primarily focused on vacuum decontamination for\nspace applications, we consider the entire pressure rangefrom\nultralow gas pressures to large gas pressures including pressures\nnear saturating vapor pressuresto also cover gas decontamination\nrelevant to other applications. In more detail, we consider the adsorption\nand trapping of molecules ranging from water, hydrocarbons, and siloxanes\nwithin existing materials such as active carbons, zeolites, mesoporous\nsilicas, and metal organic frameworks. We first provide a short introduction\nto available experimental and molecular simulations methods that allow\nprobing contaminant adsorption using nanoporous materials. Then, we\ndiscuss experimental and molecular simulation works by identifying\nsimple essential parametersthe so-called descriptorsthat\nallow describing and predicting the vapor pressure at which half pore\nfilling occurs. In this report, we also present available theoretical\nframeworks which allow capturing gas adsorption in nanoporous solids.\nBy restricting the discussion to physical models which are based on\nrigorous thermodynamic treatments, we identify available strategies\nthat provide a consistent description of adsorption data as a function\nof relevant variables such as temperature, pressure, etc. In this\ncontext, we also provide thermodynamic schemes such as Derjaguin’s\nadsorption model and Polanyi’s adsorption potential theory\nwhich provide reliable strategies to describe and extrapolate adsorption\nunder various thermodynamic conditions.