“…The decrease in permeance before the plasticization pressure is due to competitive sorption, sorption isotherm concave shape [ 67 , 68 ]. It constitutes a reduction in the driving force of transport with increasing pressure and a gradual saturation of the material which may cause lower mobility [ 69 ]. Figure 8.…”
The key challenge in the synthesis of composite mixed matrix membrane (MMMs) is the incompatible membrane fabrication using porous support in the dry–wet phase inversion technique. The key objective of this research is to synthesize thin composite ternary (amine) mixed matrix membranes on microporous support by incorporating 10 wt% of carbon molecular sieve (CMS) and 5–15 wt% of diethanolamine (DEA) in polyethersulfone (PES) dope solution for the separation of carbon dioxide (CO
2
) from methane (CH
4
) at high-pressure applications. The developed membranes were evaluated for their morphological structure, thermal and mechanical stabilities, functional groups, as well as for CO
2
-CH
4
separation performance at high pressure (10–30 bar). The results showed that the developed membranes have asymmetric structure, and they are mechanically strong at 30 bar. This new class of PES/CMS/DEA composite MMMs exhibited improved gas permeance compared to pure PES composite polymeric membrane. CO
2
-CH
4
perm-selectivity enhanced from 8.15 to 16.04 at 15 wt% of DEA at 30 bar pressure. The performance of amine composite MMMs is theoretically predicted using a modified Maxwell model. The predictions were in good agreement with experimental data after applying the optimized values with AARE % = ∼less than 2% and
R
2
= 0.99.
“…The decrease in permeance before the plasticization pressure is due to competitive sorption, sorption isotherm concave shape [ 67 , 68 ]. It constitutes a reduction in the driving force of transport with increasing pressure and a gradual saturation of the material which may cause lower mobility [ 69 ]. Figure 8.…”
The key challenge in the synthesis of composite mixed matrix membrane (MMMs) is the incompatible membrane fabrication using porous support in the dry–wet phase inversion technique. The key objective of this research is to synthesize thin composite ternary (amine) mixed matrix membranes on microporous support by incorporating 10 wt% of carbon molecular sieve (CMS) and 5–15 wt% of diethanolamine (DEA) in polyethersulfone (PES) dope solution for the separation of carbon dioxide (CO
2
) from methane (CH
4
) at high-pressure applications. The developed membranes were evaluated for their morphological structure, thermal and mechanical stabilities, functional groups, as well as for CO
2
-CH
4
separation performance at high pressure (10–30 bar). The results showed that the developed membranes have asymmetric structure, and they are mechanically strong at 30 bar. This new class of PES/CMS/DEA composite MMMs exhibited improved gas permeance compared to pure PES composite polymeric membrane. CO
2
-CH
4
perm-selectivity enhanced from 8.15 to 16.04 at 15 wt% of DEA at 30 bar pressure. The performance of amine composite MMMs is theoretically predicted using a modified Maxwell model. The predictions were in good agreement with experimental data after applying the optimized values with AARE % = ∼less than 2% and
R
2
= 0.99.
“…UiO-66 is a relatively new zirconium-based porous MOF, which is attracting attention for its highly promising properties for CO 2 /CH 4 GS, such as good selectivity, high adsorption capacity, and low cost (Ahmad et al, 2020). UiO-66 is typically prepared from inorganic nodes Zr 6 O 4 (OH) 4 (CO 2 ) 12 linked with terephthalate ligands and possesses a three-dimensional porous lattice having close to 11-and 8-Å free diameters for the two types of cages and narrow triangular windows with a free diameter close to 6 Å (Yang et al, 2011).…”
Several concepts of membranes have emerged, aiming at the enhancement of separation performance, as well as some other physicochemical properties, of the existing membrane materials. One of these concepts is the well-known mixed matrix membranes (MMMs), which combine the features of inorganic (e.g., zeolites, metal-organic frameworks, graphene, and carbon-based materials) and polymeric (e.g., polyimides, polymers of intrinsic microporosity, polysulfone, and cellulose acetate) materials. To date, it is likely that such a concept has been widely explored and developed toward low-permeability polyimides for gas separation, such as oxydianiline (ODA), tetracarboxylic dianhydride-diaminophenylindane (BTDA-DAPI), m-phenylenediamine (m-PDA), and hydroxybenzoic acid (HBA). When dealing with the gas separation performance of polyimide-based MMMs, these membranes tend to display some deficiency according to the poor polyimide-filler compatibility, which has promoted the tuning of chemical properties of those filling materials. This approach has indeed enhanced the polymer-filler interfaces, providing synergic MMMs with superior gas separation performance. Herein, the goal of this review paper is to give a critical overview of the current insights in fabricating MMMs based on chemically modified filling nanomaterials and low-permeability polyimides for selective gas separation. Special interest has been paid to the chemical modification protocols of the fillers (including good filler dispersion) and thus the relevant experimental results provoked by such approaches. Moreover, some principles, as well as the main drawbacks, occurring during the MMM preparation are also given.
“…To overcome the plasticization problem in polyimide membranes, many studies (i.e., thermal annealing, 17,18 thermally rearranged polymer, 18,19 chemical crosslinking, 14,20 mixed matrix membranes, 21,22 and polymer blending 23 ) have been reported. Among them, chemical crosslinking with diamine as a crosslinker has been widely studied using various crosslinking methods 23–26 .…”
To overcome the plasticization effect in polyimide membranes, many researchers have proposed crosslinking method. This can reduce an inter‐segmental mobility by tightening and rigidifying the polymer chains. However, it is difficult to modify the whole polymer chains throughout the membrane because the reaction can be hindered by the diffusion rate of the crosslinker. In particular, it is hard for bulky crosslinker to penetrate a dense membrane with a small d‐spacing. This study investigated the effect of crosslinking a dense Matrimid membrane with p‐phenylenediamine (p‐PDA) via two different crosslinking methods (i.e., methanol‐swelling crosslinking process [M‐SCP] and liquid‐phase crosslinking process [L‐PCP]). Most of the crosslinking reaction in M‐SCP occurs on the membrane surface due to difficulty in penetration of the bulky p‐PDA into the Matrimid dense membrane. In contrast, the L‐PCP allows uniform crosslinking across the membrane. The membranes crosslinked using L‐PCP showed excellent chemical resistance. Furthermore, the plasticization phenomenon was not observed in the membranes crosslinked using L‐PCP with p‐PDA more than 15%. Meanwhile, the membrane crosslinked using M‐SCP exhibited poor plasticization and chemical resistance properties. These results showed that the L‐PCP method can be more effective for the crosslinking of dense membrane to deliver both high plasticization and chemical resistance.
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