Improved CO2 transport properties of Matrimid membranes by adding amine-functionalized PVDF and MIL-101(Cr)

The effect of addition of ammoniated PVDF (NH2-PVDF) and amine-functionalized metal organic framework (MOF) NH2-MIL-101(Cr) were investigated on the gas permselectivity and plasticization behavior of Matrimid-based membranes for CO2/CH4 separation. The NH2-PVDF was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The NH2-MIL-101(Cr) nano-sized particles were synthesized and investigated via XRD, field emission scanning electron microscopy (FESEM), Brunauer-Emmett-Teller (BET) and dynamic light scattering (DLS). Then, the particles were dispersed in Matrimid/NH2-PVDF blend to produce ternary mixed matrix membrane (MMM). The membrane microstructures were examined by FTIR and XRD, while the uniform particle dispersion was confirmed by FESEM. Differential scanning calorimetry (DSC) showed that the Matrimid/NH2-PVDF blend is miscible up to 3 wt% of NH2-PVDF and the glass transition temperature increased with MOF content. Single-gas permeability measurements revealed that the best separation performance was obtained for the blend membrane with 3 wt% of NH2-PVDF with increased CO2 permeability and CO2/CH4 ideal selectivity by 39% and 33% respectively, over the neat Matrimid values. Much higher improvements (125% and 136% respectively) were obtained when 5 wt% of NH2-MIL-101(Cr) was added. Also, the plasticization pressure was increased from 12 to 26 bar by adding 3 wt% of NH2-PVDF and 7 wt% of MOF in the neat Matrimid.