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[Display omitted] • PEI and APTES modified MfMCNs are prepared by pre-assembly experiment. • MfMCNs contains hydroxyl and amino groups to enhance the adsorption of CO 2. • The pore size of MfMCNs decreased to 0.53–0.55 nm, which enhanced screening of CO 2. • By adding MfMCNs, the phase interface defect is improved and the separation performance of MMMs is enhanced. Traditional two-dimensional (2D) membrane fillers are prone to interfacial defects such as agglomeration and phase separation in the membrane, limiting the separation performance of membrane. In this paper, microporous carbon nanoplates (MCNs) with controllable microporous structures were functionalized with two different amine carriers of low molecular weight polyethyleneimine (PEI) and 3-aminopropyl triethoxysilane (APTES) to prepare multi-functionalized microporous carbon nanoplates (MfMCNs). It is worth noting that with the success of composite functionalization, the filling content of mixed matrix membranes is also high to a certain extent. To a certain extent, it has been demonstrated that interfacial compatibility between the polymer and the fillers has been improved. It was confirmed by characterization technology that the morphology of the fillers had not been changed, but the pore size of MfMCNs was declined to 0.53–0.55 nm because part of the amino carrier was immersed in the pore structure of MfMCNs. The gas permeability tests under dry gas and wet gas conditions show that the improvement of phase interface by MfMCNs is significant. Under the condition of a dry gas test, the CO 2 /N 2 selectivity of MfMCNs/Pebax-1.0 wt% MMMs is 76.3, which is 27 % higher than that of MCNs/Pebax-1.0 wt% MMMs. Under the moisture condition, the permeability and selectivity of MfMCNs/Pebax-1.0 wt% MMMs CO 2 are 287.72 Barrer and 79.1 separately. Compared with Pebax membrane, the permeability of CO 2 (176.6 Barrer) was rose by 62.9 %, and the selectivity of CO 2 (59.1) was rose by 33.84 %. Significantly, the best MMMs separation performance exceeds upper limit of Robeson. This provides a powerful strategy to strengthen the compatibility between inorganic materials and polymers and strengthen the performance of MMMs in CO 2 gas capture. [ABSTRACT FROM AUTHOR]

Conventional two-dimensional (2D) fillers in membranes have undesirable gas transport resistance owing to their interfacial barriers. In this work, 2D microporous carbon nanoplates (MCNs) were proposed to construct low-resistance and high-selectivity gas transport channels in mixed-matrix membranes (MMMs) to enhance the CO 2 separation performance. MCNs were synthesized using a phase-transition material as a removable template and incorporated with Pebax-1657 to prepare MMMs. Micropores measuring 0.58 nm in the MCNs provided low-resistance CO 2 diffusion channels that significantly improved CO 2 permeability, as confirmed by the diffusion coefficient calculated through molecular simulation. Meanwhile, the random and effective stacking of the MCNs in the MMMs created highly selective gas transport channels that dramatically enhanced CO 2 /N 2 selectivity. The MMMs with 0.5 wt% MCNs showed the best separation performance. In the mixed-gas test, the CO 2 permeability reached 160.69 Barrer, and the CO 2 /N 2 selectivity reached 61.2. In the pure-gas test, the CO 2 permeability and CO 2 /N 2 selectivity were 123 Barrer and 76, exhibiting distinct increases of 53.0% and 28.8% compared to those of the pristine Pebax membrane. Notably, the best CO 2 separation performance of the prepared MMMs exceeded Robeson's upper bound. The proposed template-removal 2D MCNs with low-resistance and high-selectivity transport multi-channels facilitate a new process for molecularly selective and energy-efficient CO 2 separation. Image 1 • Low-resistance and high-selectivity multi-channels were constructed by introducing MCNs in MMMs. • The structural and transport properties of MCNs/Pebax MMMs were simulated. • CO 2 /N 2 separation performance has exceeded Robeson's upper bound. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mixed matrix membranes based on Pebax-1657 and microporous ZIF-93 were successfully prepared. • Pebax molecular chains form a bridging structure with the help of ZIF-93 crystal particles to make MMMs more dense. • ZIF-93 improves CO 2 permeability and selectivity of MMMs. In the present study, ZIF-93 metal–organic frameworks were prepared. N 2 adsorption tests revealed that the particle size, specific surface area, and pore size of ZIF-93 were 30 nm–45 nm, 869.40 m2/g, and 0.36 nm, respectively. Pebax-based mixed matrix membranes (MMMs) were prepared using ZIF-93 as the filler. The pore diameters of ZIF-93 lied between the kinetic diameters of CO 2 and N 2 ; thus, its pore structure provided a fast transfer channel for CO 2 and increased the permeability of the membrane. Further, X-ray diffraction showed that the membrane became denser upon introducing ZIF-93 because of the formation of a bridging structure between the Pebax molecular chains and ZIF-93. A denser stacking by moving the Pebax molecular chains closer to each other effectively bettered the CO 2 selectivity of the mixed matrix membrane. The test results showed that when the ZIF-93 loading was 10 wt%, the CO 2 permeability was 84.85 barrer and the CO 2 /N 2 selectivity was 65.76 at 0.4 MPa, which are 51.57 % and 65.50 % higher than those of the pure Pebax membrane, respectively. When the feed pressure was increased to 0.8 MPa, the CO 2 permeability was 94.5 barrer and the CO 2 /N 2 selectivity is 87.5, which are 51.57 % and 65.50 % higher compared with those of the pure Pebax membrane, in order. The membrane performance significantly exceeded that of the 2008 Robeson curve. [ABSTRACT FROM AUTHOR]

[Display omitted] • MMMs based on Pebax-1657 and microporous CNs were successfully prepared. • CO 2 permeability and CO 2 /N 2 selectivity were improved with CNs addition. • Microporous CNs with accessible inner channels provided low-resistance transport channels for CO 2. • The CNs-600(0.5 wt%)/Pebax MMMs showed the best CO 2 permeability and selectivity. We investigated the use of microporous carbon nanospheres (CNs) as fillers to prepare mixed matrix membranes (MMMs) for permeable and selective CO 2 separation. CNs with a uniform size of 650 nm and unique amorphous structure were characterized by SEM and XRD. The N content of CNs with different carbonization temperatures was determined by XPS. The surface area and micropore size of the samples could be easily adjusted by varying the carbonization temperature; in particular, increasing the carbonization temperature improved both parameters. At 600 °C, the particles (CNs-600) exhibited a higher N content and narrower micropores, which ensured higher affinity and enhanced capture of CO 2 molecules. Thus, CNs-600/Pebax MMMs exhibited superior CO 2 separation performances compared to other CNs-based MMMs. Furthermore, when the loading of CNs-600 was 0.5 wt%, the MMMs exhibited the best CO 2 /N 2 separation properties, with a 39.51% improvement compared to pristine Pebax membranes. These outstanding performances are attributed to the fact that microporous CNs with accessible inner channels can provide a low-resistance transport pathway to gas molecules. Moreover, the strong interaction between CO 2 and the pore walls, along with the high N content, enabled an effective separation of CO 2 from other gas molecules. Importantly, the CNs-600/Pebax MMMs displayed superior CO 2 /N 2 selectivity compared to previously reported Pebax-based MMMs with other fillers. The proposed CNs, with microporous structure and high N content, may represent a promising alternative for the fillers of MMMs. [ABSTRACT FROM AUTHOR]

[Display omitted] • PSA modified hollow ZIF-8 were designed by a hard template-incomplete etching strategy. • The hollow core of PHZ builds a low-resistance CO 2 transport freeway. • The outside PSA layer intensifies the interface affinity between ZIF-8 and Pebax. The trade-off between gas permeability and selectivity represents a huge challenge for membrane separation. In this work, we design unique polystyrene-acrylate (PSA) modified hollow ZIF-8 (PHZ) nanospheres via a facile hard template-incomplete etching strategy as fillers for mixed matrix membranes (MMMs). In the vesicles shaped PHZ, the hollow core builds a low-resistance CO 2 transport freeway, leading to improved CO 2 permeability. Meanwhile, the outside PSA layer intensifies the interface affinity between ZIF-8 and Pebax through molecular chains entanglements and hydrogen bonding, enhancing membrane selectivity. Through controlling the PSA etching process, both the hollow core with tunable size and the outside PSA layer with adjustable thickness are achieved. The 10 wt% PHZ-2/Pebax MMMs present the best performance with a CO 2 permeability of 172.4 Barrer and CO 2 /N 2 selectivity of 87.9. The higher CO 2 /N 2 selectivity proves that the PSA layer on the PHZ has better compatibility with Pebax. The higher CO 2 permeability is attributed to the low-resistance hollow core. The gas separation performance of PHZ-based MMMs not only well exceeded the 2008 Robeson upper-bond line but also was superior to those of other published MOF-based MMMs. The concept of vesicle-shaped PHZ paves a way to concurrently enhance both the gas permeability and selectivity of MMMs. [ABSTRACT FROM AUTHOR]