A Threefold Interpenetrated Pillared‐Layer Metal–Organic Framework for Selective Separation of C₂H₂/CH₄ and CO₂/CH₄

Abstract

A new threefold interpenetrated pillared‐layer microporous metal–organic framework, [Zn2(cca)2(4‐bpdb)]n⋅(DMF)2n (UTSA‐85) (H2cca=4‐carboxycinnamic acid, 4‐bpdb=1,4‐bis(4‐pyridyl)‐2,3‐diaza‐1,3‐butadiene, and DMF=N,N‐dimethylformamide), has been designed and generated by the solvothermal reaction of mixed ligands (H2cca and 4‐bpdb) and Zn(NO3)2⋅6 H2O. Single‐crystal XRD analysis disclosed that discrete paddle‐wheel Zn2(COO)4 clusters as secondary building units linked the cca ligands to give two‐dimensional layers, which were further pillared by 4‐bpdb ligands to form a threefold interpenetrated pillared‐layer structure. The desolvated framework, UTSA‐85 a, was revealed to exhibit permanent porosity with a BET surface area of 558 m2 g−1 and a high selectivity of 64 for C2H2/CH4 separation at 296 K owing to the microporous (≈5.0 Å) structure and functional azine groups that decorated the pore channels.

A 3D Microporous MOF with mab Topology for Selective CO2 Adsorption and Separation

“…The CO 2 /N 2 and CO 2 /CH 4 selectivities increased with temperature and the exact reason is still unclear . The functional azine sites might play some roles through different interactions with those gas molecules . Both the CO 2 /N 2 and CO 2 /CH 4 selectivity values are higher than those of previously reported MOFs: PCN‐88 (CO 2 /N 2 : 18/296 K, CO 2 /CH 4 : 5/296 K), PCN‐61 (CO 2 /N 2 : 15/298 K), Cu 24 (TPBTM) 8 (CO 2 /N 2 : 22/298 K), ZJNU‐44a (CO 2 /N 2 : 15/296 K, CO 2 /CH 4 : 5.5/296 K), SIFSIX‐2‐Cu (CO 2 /N 2 : 13.7/298 K, CO 2 /CH 4 : 5.3/298 K), HKUST‐1 (CO 2 /N 2 : 101/293 K), PMOF‐3a (CO 2 /N 2 : 29.2/273 K and 23.4/296 K, CO 2 /CH 4 : 8/273 K and 5.1/296 K), JUC‐141 (CO 2 /N 2 : 21.6/273 K and 27.6/298 K, CO 2 /CH 4 : 4.2/273 K and 8.7/298 K), Cu‐BTTri (CO 2 /N 2 : 21/298 K), en‐Cu‐BTTri (CO 2 /N 2 : 25/298 K), NOTT‐202a (CO 2 /N 2 : 26.7/273 K and 4.3/293 K, CO 2 /CH 4 : 2.9/273 K and 1.4/293 K), MOF‐177 (CO 2 /N 2 : 3.6/296 K), Bio‐MOF‐11 (CO 2 /N 2 : 79.5/296 K), Zn‐MOF‐74 (CO 2 /N 2 : 87.7/296 K, CO 2 /CH 4 : 5/296 K), In 2 X (CO 2 /CH 4 : 6.4/273 K and 5.6/298 K), Tb(BCB), (CO 2 /CH 4 : 4.1/273 K and 2.3/296 K), InOF‐14 (CO 2 /CH 4 : 3.1/273 K and 2.4/295 K), many ZIF materials (ZIF‐68, CO 2 /N 2 : 18.7/298 K, CO 2 /CH 4 : 5/298 K; ZIF‐69, CO 2 /N 2 : 19.9/298 K, CO 2 /CH 4 : 5.1/298 K) and benchmark zeolite Cu‐SSZ13 (CO 2 /N 2 : 67.4/296 K), zeolite MFI (CO 2 /N 2 : 11.2/296 K) under the similar conditions (Table S4, Supporting Information) ,.…”

“…The results of IAST calculations have shown that under 1 bar, the selectivity for CO 2 /N 2 mixture is 57 at 273 K and 121.4 at 295 K; the selectivity for CO 2 /CH 4 mixture is 8.4 at 273 K and 8.8 at 295 K (Figure (c) and 3(f)). The CO 2 /N 2 and CO 2 /CH 4 selectivities increased with temperature and the exact reason is still unclear . The functional azine sites might play some roles through different interactions with those gas molecules .…”

A Moisture‐Stable 3D Microporous CoII‐Metal–Organic Framework with Potential for Highly Selective CO2 Separation under Ambient Conditions

“…Both CO 2 /N 2 and CO 2 /CH 4 selectivity at different temperatures and desired pressures with methods of selectivity calculations (IAST, isotherm slopes, Henry Law) based on through literature survey is presented in Table S4, Supporting Information. The selectivities increased with pressure and the exact reason is still unclear,,,,,, however, this might be attributed to different adsorption sites in the framework that are successively occupied with increasing pressure. It is worth mentioning that IITKGP‐8 a has the modest CO 2 uptake capacity but displays a higher CO 2 /N 2 selectivity and moderate CO 2 /CH 4 selectivity, underlying the uniqueness of this new MOF for potential application in carbon capture and separation from landfill gas and flue gas as well.…”

Paddlewheel SBU based Zn MOFs: Syntheses, Structural Diversity, and CO2 Adsorption Properties

“…For example, Zn MOFs [Zn 2 (1,4-bdc) 2 (dabco)] and [Zn 2 (1,4-bdc) 2 (bpy)], where 1,4-H 2 bdc = benzene-1,4-dicarboxylic acid, dabco = diazabicyclo[2.2.2]octane, and bpy = 4,4′-bipyridine, both show pcu and kag net topologies [22]; such results are tentatively attributed to the degree of deviation of the conformations of the paddlewheel SBUs. Of note, this also suggests that judicially designed and modified MOFs may be promising porous materials for applications in gas adsorption such as carbon dioxide (CO 2 ) capture [2,3,4,5,23,24,25,26,27,28,29,30]. For example, Zn MOF [Zn 2 (cca)(4-bpdb) 2 ] (H 2 cca = 4-carboxycinnamaic acid, 4-bpdb = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene) has shown noticeable CO 2 uptakes of 54.2 cm 3 /g at 273 K and 38.9 cm 3 /g at 298 K [30].…”