3-Dimensionally disordered mesoporous silica (DMS)-containing mixed matrix membranes for CO2 and non-CO2 greenhouse gas separations

• Membrane-based N2/NF3 separations were reported for the first time.
• Commercial 3-D disordered mesoporous silica was utilized as molecular sieves.
• Our MMM showed N2 permeability of 17.5 Barrer with N2/NF3 permselectivity of 10.7.
• The CO2/N2 and CO2/CH4 separation performance of our MMMs was promising.
• Permeability increase of MMMs varies due to variance in interfacial polymer chains.

The effect of 3-dimensionally disordered mesoporous silica (DMS) was investigated on the transport of two different glassy polymer matrices, 6FDA-DAM:DABA (3:2) and polysulfone (PSf). More specifically, single gas (i.e. N2, CO2, CH4 and NF3) permeabilities of the mixed matrix membranes (MMMs) were characterized as a function of DMS volume fractions. Our permeation results demonstrated that both 6FDA-DAM:DABA (3:2)- and PSf-based MMMs with a nominal DMS weight fraction of 0.2 substantially improved all the single gas permeabilities mainly due to the diffusivity improvement. Such a significant increase in diffusivity is attributed to the 3-dimensionally interconnected pore structures of DMS particles. NF3, a missing greenhouse gas, exhibited the permeability improvement mechanism different from other gases. Besides, at the relatively lower DMS loading, difference in the extent of increase in permeability was observed for two different polymer cases. It was explained presumably by the effect of a high resistance zone-of-influence, or the rigidification of matrix polymer chains around inorganic particles. Our study suggests that 3-dimensional DMS particle-containing MMMs can provide a useful material platform for separating N2/NF3, CO2/CH4, and CO2/N2, by substantially increasing permeability, thereby cutting down the capital cost of membrane units.

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