Two Solvent-Induced In(III)-Based Metal–Organic Frameworks with Controllable Topology Performing High-Efficiency Separation of C₂H₂/CH₄ and CO₂/CH₄

Abstract

For pure acetylene manufacturing and natural gas purification, the development of porous materials displaying highly selective C 2 H 2 /CH 4 and CO 2 /CH 4 separation is greatly important but remains a major challenge. In this work, a plausible strategy involving solvent-induced effects and using the flexibility of the ligand conformation to make two In(III) metal−organic frameworks (MOFs) is developed, showing topological diversity and different stability. The X-shaped tetracarboxylic ligand H 4 TPTA ([1,1′:3′,1″-terphenyl]-4,4′,4″,6′-tetracarboxylic acid) was selected to construct two new heteroid In MOFs, namely, {[showing a pts topology with a large channel that is not conducive to fine gas separation. By contrast, with the reduction of SBU from uninucleated In to an {In-OH-In} n chain, MOF 2 has a (4, 6)connected net with the fsc topology with an ∼5 Å suitable micropore to confine matching small gas. The permanent porosity of MOF 2 leads to the preferential adsorption of C 2 H 2 over CO 2 with superior C 2 H 2 /CH 4 (332.3) and CO 2 /CH 4 (31.2) separation selectivities. Meanwhile, the cycling dynamic breakthrough experiments showed that the high-purity C 2 H 2 (>99.8%) capture capacities of MOF 2 were >1.92 mmol g −1 from a binary C 2 H 2 /CH 4 mixture, and its separation factor reached 10.

Synthesis of Ultramicroporous Materials via Cross-Linking Reaction of Polynaphthalene

“…The N 2 adsorption capacity at 273.15 K/1.0 bar is 0.61 mmol/g, and CH 4 adsorption capacities at 273.15 K/1.0 bar and 298.15 K/1.0 bar are 1.57 and 1.14 mmol/g, respectively. The adsorption data of CH 4 at 273.15 K/1.0 bar are higher than those of some materials prepared in the past two years, such as SNNU-5-Sc (1.21 mmol g −1 ), CNOP-2 (1.37 mmol g −1 ), CTP-1-NH 2 (1.50 mmol g −1 ), and MOF-2 (0.63 mmol g −1 ) . Moreover, we also gained important data about the separations of CO 2 from N 2 and CH 4 .…”

Theoretical investigation of C1–C4 hydrocarbons adsorption and separation in a porous metallocavitand

“…† The CH 4 adsorption in PPX is remarkable with 2.37 mmol g −1 and only NOTT-101 (5.93 mmol g −1 )/-101-IPA (5.98 mmol g −1 ) 49 achieved higher than these limits. The C 2 H 2 adsorption in PPX is 2.80 mmol g −1 , although the adsorption is not very good but performs better than UPC-98, 50 UMCM-151, 51 PFC-5, 52 FIR-125, 53 NUM-9a, 54 JLU-Liu45, 55 Zr-OBBA, 55 PFC-1/-2, 56 NUM-7, 57 Cu-F-pymo, 58 MOF 1/MOF 2, 59 UPC-99, 60 NbU-1. 61 C 2 H 4 adsorption was also impressive with 4.26 mmol g −1 and only MFM-300(In) 62 (4.9 mmol g −1 ), and Dps-VCo-BDC (7.41 mmol g −1 )/tpt-VCo-BDC(6.29 mmol g −1 ) 63 MOF is higher than PPX limit.…”

Ligand Torsion Engineering in Three Flexible Metal–Organic-Frameworks Exhibiting Distinct Breathing Behavior for Enhancing C2H2 Capture

“…The trade-off between selectivity and adsorption capacity is still a major obstacle. , To date, there are strategies as follows: (i) affording high surface areas and large pore volume, (ii) hard–soft acid–base (HSAB) theory that can strengthen the interaction between the framework and the specific gas molecules, and (iii) introducing open metal sites (OMSs). Lately, our group has also done several works in the field of MOFs’ ion detection and gas adsorption and separation by using multifunctional aromatic N,O-donor ligand H 2 DTTA = 2,5-di­(1 H -1,2,4-triazol-1-yl). ,, On the basis of the theory of HSAB, the hard bases, for instance, carboxylate groups tend to combine with high-valent metal ions, while the soft bases, like azoles, can form stronger coordination bonds with low-valent transition metal ions. Considering the significance of structural dynamics and metal ions in flexible MOFs for gas sorption, in this work, a series of flexible MOFs were synthesized using this ligand (Scheme ), although compound 2 was synthesized with diverse synthetic methods, which reported for selective turn-on fluorescence DMSO residual sensing, the acetylene adsorption was further investigated.…”

“…Recently, porous material for adsorption separation is an energy-saving and environmentally friendly technology. Metal–organic frameworks (MOFs) that consist of metal or metal cluster nodes and ligand linkers have received widespread attention in gas adsorption and separation, − luminescence, − drug delivery, , magnetic, microwave absorption, perovskite solar cells, and catalysis. − As a subcategory of MOFs, flexible MOFs (FMOFs) remain at the forefront of porous materials research, in certain cases exhibiting unusual breathing behavior where a sudden increase in adsorption happens accompanied with the change in the pore structure at a gate opening pressure induced by structural distortion, , temperature, , mechanical pressure, , or light. , It is more suitable for separating target species from mixtures, and selective gate-opening adsorption with remarkable structural transformations in FMOFs renders them beneficial for gas storage and separation. − …”