Mixed matrix membranes of 6FDA-6FpDA with surface functionalized γ-alumina particles. An analysis of the improvement of permselectivity for several gas pairs

Herein, mixed matrix membranes including alumina particles whose surfaces have been differently modified have been made and characterized. The polymeric matrix is a fluorinated polyimide, 6FDA-6FpDA, whereas the inorganic constituent parts are neat, silanized or poly-vinyl-pirrolidone-coated nanometric γ-Al2O3 particles of 40 nm in diameter, which have been added in an approximated percentage of a 12% w/w.All the modified or unmodified added particles lead to similar improvements in the permselectivity of the gas pairs studied. Only in the case of the O2/N2 pair the increase in selectivity for the silanized particles is not as effective as the observed permeability enhancement for the uncoated and PVP-coated particles. In case of CO2/CH4, the 1991 Robeson's upper bond line is overpassed.The characteristics of the permselectivity improvement for the different inorganic particles have been analyzed in terms of the properties of the particle–polymer interfacial properties.