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AbstractThe removal of carbon dioxide (CO2) from acetylene (C2H2) represents a pivotal industrial process for the production of high-purity C2H2. Nevertheless, the separation of C2H2 and CO2 is challenging due to their highly similar molecular sizes and physical properties. In this work, we report a fine regulation of a sql layered coordination polymer (termed NTU-107) into a rare fsc open framework (termed NTU-108) with naphthalenedisulphonic acid pillar for selective C2H2 capture from CO2-contained mixtures. NTU-107 was prepared by the reaction of 4-(1H-imidazol-1-yl)benzoic acid (L1) ligand and Cu2+ ion, showing a layered framework with a pore size of 4.2 Å. After inserting 1,5-naphthalenedisulphonic acid between the layers, a new pillar-layered open framework (5.8 Å) with sulphonic acid functional sites was prepared. Single-component gas adsorption experiments and breakthrough experiments demonstrated that NTU-108 with accessible sulphonic acid sites exhibits a high C2H2 absorption capacity and dynamic C2H2/CO2 separation performance at room temperature. [ABSTRACT FROM AUTHOR]

Mixed-matrix membranes, which are fabricated by incorporating dispersed fillers into continuous polymers, have been considered as a promising and feasible platform for highly efficient gas separation. However, few have impurity-adapted nanochannels. Herein we present a group of mixed-matrix membranes (MMMs) incorporating a soft metal-organic framework (NTU-88c , activated NTU-88) into 6FDA-DAM. The rotation of the pyridyl rings of the ligands in NTU-88c creates a nanochannel with an aperture size of 3.4 Å, which falls between the kinetic parameters of CO 2 (3.3 Å) and CH 4 (3.8 Å). The membrane shows enhanced CO 2 permeability (1140 Barrer) at 60 °C, accompanied by a good separation factor of 45. In addition, an increase in feed gas pressure 1.0 MPa (25 °C) resulted in a notable enhancement in CO 2 permeability (645 Barrer), accompanied by a high CO 2 /CH 4 separation factor (41). More importantly, the MMM has demonstrated durable and stable CO 2 /CH 4 separation performance in long-term test, exceeding the Robeson upper-bound, suggesting a promising potential for natural gas purification. Moving forward, the findings of this work not only demonstrate the importance of porous fillers that have impurity-adapted nanochannels for membrane separation, but also offer a route to design and construct high-performance MMMs for feasible applications. [Display omitted] • Mixed-matrix membranes were prepared with a soft MOF having a CO 2 -adapted nanochannel. • The CO 2 -adapted nanochannel was confirmed by gas-loaded X-ray diffraction analysis and modelling calculations. • The separation performance of the MMM with NTU-88 was sharply enhanced at a relatively high pressure and temperature. • The CO 2 /CH 4 separation performance of this MMM exceeds the Robeson upper-bound. [ABSTRACT FROM AUTHOR]

Hierarchical supramolecular frameworks are being designed and constructed for various applications, yet the controlled assembly and process understanding incorporating giant building blocks remains a great challenge. Here, we report a strategy of "rivet" substitution and "hinge" linkage for the controlled assembly of the hierarchical supramolecular framework. The replacement of two "rivet" ethylene glycol (EG) molecules for triangular prism [Zn 9 ] (a small block in 1) with a 1,3-propanediol (PDO) provides space for a "hinge" linkage from adjacent ligands, thus providing a hierarchical (from micro- to mesopores, from the internal cavity to external surface) supramolecular framework (2) based on a coordinative subblock with the record number of zinc ions ([Zn 54 ]). Time-dependent powder X-ray diffraction and ESI-MS technology were used to assess the in situ evolution process: logically progressing from [Zn 9 ] to [Zn 18 ], then to [Zn 27 ], and finally to [Zn 54 ]. The sequential transformation entails two types of half-opening cavities and two types of internal microcages. Further aggregation of [Zn 54 ] in dia topology engenders the formation of a one-dimensional channel (10 Å), and an additional mesocage with a volume of 16 × 16 × 55 Å 3 . The diverse pore system exhibits an impressive uptake capability (3.19 g g -1 ) for iodine vapor at 75 °C and effective ethylene purification. Our investigations represent a valuable avenue for assembling a giant subblock and hierarchical supramolecular framework, facilitating multi-functional molecular accommodation., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

The adsorptive separation of ternary propyne (C 3 H 4 )/propylene (C 3 H 6 )/propane (C 3 H 8 ) mixtures is of significant importance due to its energy efficiency. However, achieving this process using an adsorbent has not yet been accomplished. To tackle such a challenge, herein, we present a novel approach of fine-regulation of the gradient of gate-opening in soft nanoporous crystals. Through node substitution, an exclusive gate-opening to C 3 H 4 (17.1 kPa) in NTU-65-FeZr has been tailored into a sequential response of C 3 H 4 (1.6 kPa), C 3 H 6 (19.4 kPa), and finally C 3 H 8 (57.2 kPa) in NTU-65-CoTi, of which the gradient framework changes have been validated by in situ powder X-ray diffractions and modeling calculations. Such a significant breakthrough enables NTU-65-CoTi to sieve the ternary mixtures of C 3 H 4 /C 3 H 6 /C 3 H 8 under ambient conditions, particularly, highly pure C 3 H 8 (99.9%) and C 3 H 6 (99.5%) can be obtained from the vacuum PSA scheme. In addition, the fully reversible structural change ensures no loss in performance during the cycling dynamic separations. Moving forward, regulating gradient gate-opening can be conveniently extended to other families of soft nanoporous crystals, making it a powerful tool to optimize these materials for more complex applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Highly selective CO 2 capture from flue gas based on adsorption technology is among the largest challenge on the horizon, due to its high temperature (>333 K), lower partial pressure (0.1-0.2 bar), and competition from water. Due to the designable and tunable pore system, porous coordination polymers (PCPs) have been considered as the most exciting discoveries in porous materials. However, the rational design and function-led preparation of the pore system that permits highly selective CO 2 capture from flue gas (CO 2 /N 2 /O 2 /CO/H 2 O) remains a great challenge. Herein, we report a highly selective CO 2 capture from wet-hot (363 K, RH = 40%) flue gas by a robust trap-and-flow crystal ( NTU-67 ). Crystallographic analysis showed that the flow channel provides plausible CO 2 traffic, while the confined trap works as an accommodation for captured gas molecules. Further, the hydrophobic pore surface endows the function of the channels that are not influenced by hot moisture, a major obstacle to overcome direct CO 2 capture by PCPs. The integral nature of NTU-67 , including good stability in SO 2 , meets the key prerequisites that are usually considered for practical applications. The molecular insight and highly efficient CO 2 capture make us believe that different nanospace with their own duties may be extended into ingenious design of more advanced adsorbents for cost-effective and promising for CO 2 capture from flue gas.

Energy-efficient separation of propylene (C 3 H 6 )/propane (C 3 H 8 ) is in high demand for the chemical industry. However, this process is challenging due to the imperceptible difference in molecular sizes of these gases. Here, we report a continuous water nanotube dedicatedly confined in a Cu 10 O 13 -based metal-organic framework (MOF) that can exclusively adsorb C 3 H 6 over C 3 H 8 with a record-high selectivity of 1570 (at 1 bar and 298 K) among all the porous materials. Such a high selectivity originates from a new mechanism of initial expansion and subsequent contraction of confined water nanotubes (∼4.5 Å) caused by C 3 H 6 adsorption rather than C 3 H 8 . Such unique response was further confirmed by breakthrough measurements, in which one adsorption/desorption cycle yields each component of the binary mixture high purity (C 3 H 6 : 98.8%; C 3 H 8 : >99.5%) and good C 3 H 6 productivity (1.6 mL mL -1 ). Additionally, benefiting from the high robustness of the framework, the water nanotubes can be facilely recovered by soaking the MOF in water, ensuring long-term use. The molecular insight here demonstrates that the confining strategy opens a new route for expanding the function of MOFs, particularly for the sole recognition from challenging mixtures.