Hybrid mesoporous materials for carbon dioxide separation

A common method for CO2 separation from mixed gas streams is by absorption in aqueous solutions of alkanolamines. Solid phase hexagonal mesoporous silicas (HMS) of known porosity (pore diameter) were modified using aminopropyl-trimethoxysilane and related compounds to provide very high surface area materials with varied concentrations of surface bound amine and hydroxyl functional groups. The modified HMS materials reversibly adsorbed substantially more CO2 than previously observed for modified silica gel. There is substantial scope to further tailor the surface of HMS materials to realize higher adsorption capacities and more selective adsorption behavior. On a stoichiometric basis, the same adsorption capacities were observed as for the liquid phase absorption process. Thus, the development of a solid phase adsorption analogue of the current liquid phase absorption process might offer technical benefits.