Ultem®/ZIF-8 Mixed Matrix Membranes for Gas Separation: Transport and Physical Properties

Abstract

Mixed matrix membranes are promising options for improving gas separation processes. Zeolitic imidazolate frameworks (ZIFs) have a porous structure similar to conventional zeolites, being capable in principle of separating gases based on their differences in kinetic diameter while offering the advantage of having a partial organic character. This partial organic nature improves the compatibility between the sieve and the polymer, and a combination of the mentioned characteristics makes these hybrid materials interesting for the preparation of mixed matrix gas separation membranes. In this context the present work reports the preparation of Ultem  /ZIF-8 mixed matrix membranes and their permeabilities to pure CO 2 , N 2 and CH 4 gases. A significant increase in permeability with increase in CO 2 /N 2 selectivity was observed for the mixed matrix systems as compared to the properties of the neat Ultem  . Sorption results allowed to speculate that the ZIF-8 framework is not completely stable dimensionally, what influences the separation process by allowing gases with higher kinetic diameter than its nominal aperture to be sorbed and to diffuse through the crystal. Sorption and diffusion selectivities indicate that the higher separation performance of the mixed matrix membranes is governed by the diffusion process associated with the influence of gas molecule´s geometry.

Tailoring CO2/CH4 Separation Performance of Mixed Matrix Membranes by Using ZIF-8 Particles Functionalized with Different Amine Groups

“…where µ CO 2 is the contribution of filler for enhancement of CO 2 gas permeability, P CM The peak that appears at 2θ = 7.50 • are related to X-ray reflection from the plane (110) of ZIF-8 crystalline structure and is used as a reference of the ZIF-8 identification [37]. These patterns are in good agreement with the reported literature [44,45,50], which confirmed the phase purity of ZIF-8.…”

“…It can be seen from Figure 3 that amine-functionalized ZIF-8 fillers are encapsulated in the polymer phase (M1-M6). Besides, the presence of concentric cavities in membranes M2, M3, M5 and M6 demonstrated strong interfacial contact between amine-functionalized ZIF-8 fillers and 6FDAdurene polymer [37,41]. However, membranes incorporated with APTMS-ZIF-8 fillers (M1 and M4) showed different morphology compared to the other membranes incorporated with AAPTMS-ZIF8 fillers (M2 and M5) and AEPTMS-ZIF-8 fillers (M3 and M4).…”

“…This might be due to the self-condensation between aminopropyl-silane molecules, which may form a cluster on the ZIF-8 filler surface [56]. [37,41]. However, membranes incorporated with APTMS-ZIF-8 fillers (M1 and M4) showed different morphology compared to the other membranes incorporated with AAPTMS-ZIF8 fillers (M2 and M5) and AEPTMS-ZIF-8 fillers (M3 and M4).…”

In situ carbon deposition in polyetherimide/SAPO‐34 mixed matrix membrane for efficient CO2/CH4 separation

“…The fillers may be zeolite, [4][5][6][7] nonporous silica, 8,9 carbon molecular sieves, 10 activated carbons, 11 carbon nanotube, 12 metal oxides, 13 and metal organic framework. [14][15][16][17][18][19][20][21][22] In case of inorganic filler, zeolites could be used as potential material for synthesis of MMM due to the presence of continuous connected uniform molecule-sized pores which were considered as diffusion pathways. Among various types of zeolite, small pore zeolites especially, silicoaluminophosphate (SAPO-34) with a chabazite type framework with pore diameter 0.38 nm, considered as interesting fillers due to its small pore size and high adsorption affinity to CO 2 .…”

A Dual-mode model interpretation of CO2/CH4 permeability in polysulfone membranes at low pressures

“…PSf has low cost regarding to others high performance polymers, has high chemical resistance (acid, alkali, salt solutions, detergents, oils and alcohols) and good mechanical properties. Blends of PSf with others polymers and inorganic materials have being also evaluated for the separation of CO 2 (Qin and Chung 2006, Ahn et al 2008, Basu et al 2010b, Deng and Hägg 2010, Rafiq et al 2012, Eiras et al 2016. The phase inversion is a process widely used for the synthesis of polymeric membranes.…”