Investigation and comparison of mixed matrix membranes composed of polyimide matrimid with ZIF - 8, silicalite, and SAPO - 34

Mixed Matrix type membranes (MMMs) containing 10 wt% of either silicalite, SAPO - 34, and ZIF - 8 in polyimide Matrimid were fabricated and tested for their suitability to separate a number of gas mixtures by conducting single gas permeation experiments using H2, CO2, N2, and CH4 gases. The transport of these gases through the polymeric and inorganic membrane phases, as well as their interfacial voids, have additionally been distinguished from each other by fabricating MMMs containing non-calcined fillers of silicalite and SAPO-34. The ideal selectivities that have been calculated using the experimentally determined permeabilities can be attributed to the relative pore size and volume of the fillers in each membrane, as well as changes to the mobility of polymer chains in the vicinity of fillers. Due to its large pore volume as well as simultaneous reductions of interfacial voids and polymer chain mobility, ideal selectivities and gas permeabilities that are higher than those achieved by a neat Matrimid membrane have been achieved using ZIF - 8 containing MMMs. For the ZIF - 8 containing membranes, the largest permeabilities for H2, CO2, N2, and CH4 were found to be 51.1, 15.5, 0.64, and 0.54 barrer, respectively. This H2 permeability in particular was found to be the most outstanding out of all of the membranes that have been tested, and ideal selectivities for the separation of H2/N2, and H2/CH4, were found to be 80.3 and 102, respectively. The performance of the membranes that were fabricated using uncalcined silicalite and SAPO-34 also suggest that the structure of the Matrimid phase is altered by the addition of these fillers as greater selectivities at the expense of permeability were also achieved using these MMMs in comparison to a neat Matrimid membrane.