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[Display omitted] • Hollow ZIF-8 in micron accumulated continuously across membrane to construct transport highway. • The real CO 2 transport distance was reduced. • In-situ polymerization intensifies the interface affinity between ZIF-8 and PEO. The hollow filler has been verified to effectively enhance the CO 2 permeability of mixed matrix membrane (MMMs) by constructing low-resistance transport pathway. However, the in-continuity of hollow fillers across the membrane results in insufficient CO 2 permeability. In this work, the micron-sized hollow ZIF-8 (Mic-H-ZIF-8) were designed and proposed to accumulate continuously across the membrane to construct the transport highway for CO 2. Importantly, the in-situ polymerization was utilized to achieve continuous accumulation of the Mic-H-ZIF-8 fillers across the membrane. The Mic-H-ZIF-8 presents cavity size of 4 μm and shell thickness of 100 nm, and three or four Mic-H-ZIF-8 microspheres are aligned sequentially across the membrane, in which the effective gas transport distance is decreased from 13 μm to the range of 0.8–3 μm. Consequently, the CO 2 permeability of 5 wt% Mic-H-ZIF-8/PEO MMM is 224.6 % and 63.5 % higher than those of pure PEO membrane and nanosized hollow ZIF-8/PEO MMM at 0.1 MPa. Meanwhile, the CO 2 /N 2 selectivity is still as high as 70.0. This CO 2 separation performance is far exceeding the Robeson upper bound in 2008, and beyond the McKeown upper bound in 2019 as the feed pressure increasing, confirming the significance of continuous transport highway constructed by micron-sized hollow MOFs on improving CO 2 separation of MMMs. [ABSTRACT FROM AUTHOR]

Facilitated transport membrane with fixed and mobile carriers is essential yet challenging to improve the CO 2 capture. Herein, a facilitated transport membrane with continuous pathway was constructed by the in-situ interlinkage of mobile aniline with the fixed carriers distributing along electrospun polyacrylonitrile (PAN) nanofibers. In this membrane, fixed amine carriers are introduced through the alkalinous hydrolysis of PAN fibers (HPAN), and are distributed along the HPAN fibers to construct a long-range continuous transport pathway for CO 2. The mobile aniline carriers are introduced into the interfibrous voids of the HPAN nanofibers mat (NFM) by in-situ polymerization of Poly (ethylene glycol) diacrylate (PEGDA), which interlink the fixed amine carriers to achieve the facilitated transport pathway continuous completely. And the fixed amine and mobile aniline carriers are demonstrated to co-exist in the An/PEO@HPAN membrane (NFCM) by the FTIR and XPS results. Meanwhile, the XRD and DSC results indicate that the introduction of aniline increases the free volume of PEO matrix, which is beneficial for enhancing CO 2 permeation. Therefore, the 10 wt% An/PEO@HPAN-3h NFCM presents 90.81 % and 13.15 % increases in CO 2 permeability and CO 2 /N 2 selectivity under mixed gas at 0.3 MPa in contrast with the membrane without mobile aniline carriers. Under mixed gas conditions, this NFCM exhibits CO 2 permeability of 202.93 Barrer and CO 2 /N 2 selectivity of 83.89 at 0.1 MPa, reaching the 2019 McKeown upper bound. [Display omitted] • Fixed amine carriers are distributed along the HPAN nanofibers. • Mobile aniline carriers are introduced with in-situ polymerization of PEGDA. • Aniline interlinks the long-range continuous transport pathway in short range. • Continuous facilitated transport pathway improves CO 2 permeability. [ABSTRACT FROM AUTHOR]