Amine-functionalized SBA-15 in poly(styrene-b-butadiene-b-styrene) (SBS) yields permeable and selective nanostructured membranes for gas separation

Abstract

New nanostructured hybrid membranes for gas separation have been prepared and characterized for the first time in the literature by using a block copolymer, poly(styrene-b-butadiene-b-styrene) (SBS), and aminated SBA-15. Short mesopore channels, platelet SBA-15 particles with a high surface density of 3-aminopropyl grafts (3.8 nm⁻²) and modest surface area reduction (45%) were prepared, characterized and used as a filler. The gas transport characterization of the hybrid membranes indicates that with a 10 wt% content of aminated filler, outstanding performances in terms of selectivity and permeability for the CH₄/N₂ and the CO₂/N₂ gas pairs can be obtained. In particular, the CH₄/N₂ ideal selectivity of 7.3 is higher than the values of the existing block co-polymers used for this separation and of mixed matrix membranes described to date in the literature. Membranes with such a high separation factor may enable the exploitation of natural gas with high N₂ content and increase the amount of methane that can be economically recovered. The combination of the CO₂/N₂ ideal selectivity of 53 with a CO₂ permeability of 173 Barrer demonstrates that the new hybrid membranes prepared in this study deserve further attention as a practical commercial solution also for the post-combustion capture of carbon dioxide. Finally, the small and flat particles dispersed in the polymer lend themselves to the fabrication of thin industrial membranes with enhanced productivity.