Fine‐Tuned Ultra‐Microporous Metal–Organic Framework in Mixed‐Matrix Membrane: Pore‐Tailoring Optimization for C₂H₂/C₂H₄ Separation

Abstract

Effective separation of ethyne from ethyne/ethylene (C2H2/C2H4) mixtures is a challenging and crucial industrial process. Herein, an ultra‐microporous metal–organic framework (MOF) platform, Cd(dicarboxylate)2(ditriazole), with triangular channels is proposed for high‐efficiency separation of C2H2 from C2H4. The targeted structures are constructed via a mixed‐ligand strategy by selecting different‐sized ligands, allowing for tunable pore sizes and volumes. The pore properties can be further optimized by additional modification via pore environment tailoring. This concept leads to the successful synthesis of three ultra‐microporous Cd‐MOFs (JLU‐MOF87–89). As intended, C2H2 uptake and C2H2/C2H4 selectivity gradually increase with progressively optimizing the pore structure by adjusting ligand length and substituents. JLU‐MOF89, functionalized with methyl groups, features the most optimal pore chemistry and shows selective recognition of C2H2 over C2H4, owing to the framework–C2H2 host–guest interactions. Furthermore, JLU‐MOFs are fabricated into mixed‐matrix membranes for C2H2/C2H4 separation. C2H2 permeability and C2H2/C2H4 permselectivity are substantially enhanced by ≥400% and ≥200%, respectively, after hybridization of JLU‐MOF88 and JLU‐MOF89 with a polyimide polymer (6FDA–ODA). These membranes can work efficiently and are stable under different conditions, demonstrating their potential in actual ethyne separation.

A stable ultra-microporous hafnium-based metal–organic framework with high performance for CO2 adsorption and separation

“…48 In comparison with conventional zeolites and activated carbons, MOF materials with pore sizes below 5–7 Å were called ultra-microporous MOFs, and are emerging star materials that display many advantages for solving the issues of separation of important syngas. 49,50 Fortunately, our synthesized novel Hf-MOF is such a kind of ultra-microporous MOF. Meanwhile, our Hf-MOF also possesses excellent chemical stability, thus showing great practical value for CO 2 separation.…”

Anisotropic porosity and interface synergy enhanced gas permselectivity in heterolayer metal-organic framework membrane

“…[8][9][10] Integrating MOFs into membranes, either independently or within polymer composites, facilitates precise molecular sieving. [9,[11][12][13][14] Nonetheless, challenges persist, including striking the right balance between selectivity and permeability, as well as overcoming scalability limitations. Surmounting these obstacles is paramount for the advancement of membrane-based separation technology.…”

Enhancing the sensitivity of a water stable MOF as a H2S gas sensor by the fabrication of a mixed-matrix membrane

“…Coordination polymers (CPs)/metal–organic frameworks (MOFs) have been at the center of attraction over the last two decades owing to their multi-dimensional applications in gas separation and storage, 25–29 guest inclusion, 30 proton conductivity, 31 sensing, 32–37 magnetism, 38 and catalysis. 39,40 MOFs are considered for these applications given their high thermal, and chemical, stability, large porosity, tunable surface area, and amenability for post-synthetic modifications.…”

“…[13][14][15][16][17] To date, three fundamental strategies are in use for the development of fluorescent H 2 S probes based on their reaction with H 2 S: (a) reductive reaction with H 2 S: reduction of nitro or azide to amine, and reduction of selenoxide to selenide; (b) nucleophilic addition reaction by H 2 S: Michael addition reactions, addition to double bonds, dual nucleophilic reactions and thiolysis reactions; (c) precipitation reactions by H 2 S as Hg 2+ /Cu 2+ / Au 2+ /Ag + sulfides. [18][19][20][21][22][23][24] Coordination polymers (CPs)/metal-organic frameworks (MOFs) have been at the center of attraction over the last two decades owing to their multi-dimensional applications in gas separation and storage, [25][26][27][28][29] guest inclusion, 30 proton conductivity, 31 sensing, [32][33][34][35][36][37] magnetism, 38 and catalysis. 39,40 MOFs are considered for these applications given their high thermal, and chemical, stability, large porosity, tunable surface area, and amenability for post-synthetic modifications.…”