Optimized Pore Nanospace through the Construction of a Cagelike Metal–Organic Framework for CO₂/N₂ Separation

Abstract

The development of metal−organic framework (MOF) adsorbents with a potential molecule sieving effect for CO 2 capture and separation from flue gas is of critical importance for reducing the CO 2 emissions to the atmosphere yet challenging. Herein, a cagelike MOF with a suitable cage window size falling between CO 2 and N 2 and the cavity has been constructed to evaluate its CO 2 /N 2 separation performance. It is noteworthy that the introduction of coordinated dimethylamine (DMA) and N,N′-dimethylformamide (DMF) molecules not only significantly reduces the cage window size but also enhances the framework− CO 2 interaction via C−H•••O hydrogen bonds, as proven by molecular modeling, thus leading to an improved CO 2 separation performance. Moreover, transient breakthrough experiments corroborate the efficient CO 2 /N 2 separation, revealing that the introduction of DMA and DMF molecules plays a vital role in the separation of a CO 2 /N 2 gas mixture.

Solvent-Induced In(III)-MOFs with Controllable Interpenetration Degree Performing High-Efficiency Separation of CO2/N2 and CO2/CH4

“…These findings suggest that In-MOF-2 exhibits a propensity for selectively capturing CO 2 from CO 2 /N 2 and CO 2 /CH 4 mixtures. Moreover, the lower Q st value for CO 2 at zero coverage in In-MOF-2 is comparable to those of other known MOFs, such as MOF-889 (28.0), 37 FZU (30.6), 33 NENU-520 (33.0), 38 NJU-Bai35 (33.4), 33 FJUT-4 (35.2), 39 TMU-5 (45.0), 40 LIFM-11 (53.0), 41 SiFSiX-3-Ni (54.6), 42 Zn 2 (Atz) 2 Ox (55.0) 43 (Figure 5c). The CO 2 Q st value observed in In-MOF-2 indicates not only low energy consumption for adsorbent regeneration but also a strong affinity of the framework toward CO 2 molecules and weak adsorption toward N 2 and CH 4 .…”

Exquisitely Constructing a Robust MOF with Dual Pore Sizes for Efficient CO2 Capture

“…As shown in Figure 1D, there is a minor weight loss starting from 30 to 290 • C, which is mainly attributed to the removal of guest solvents, and then a major weight loss emerged after 290 • C, indicating the framework collapse of the material. The TGA curve shows the high thermal robustness of the material until 290 • C, which is superior to most recently-reported CO 2 adsorbents, including Mg-gallate (140 • C) [27], dptz-CuTiF6 (150 • C) [21], SIFSIX-3-Zn (160 • C) [28], FJUT-4 (200 • C) [29], and dptz-CuGeF 6 (200 • C) [30], MUT-4 (250 • C) [31], as well as slight lower than that of TiFSIX-Cu-TPA (308 • C) [19] and CALF-20 (350 • C) [32] (Figure 1D).…”

“…The isosteric heat (Q st ) of CO 2 was calculated using the Clausius-Clapeyron equation [25] based on adsorption isotherms at 283 and 298 K, demonstrating a value of 27.0 kJ mol −1 at CO 2 loading of 0.1 mmol/g (Figure 2B). Its Q st value is much lower than aqueous amine (105 kJ/mol) [21] and many MOF adsorbents (Figure 2C), including Mg 2 (dobpdc)(3-4-3) (99 kJ/mol) [20], Cu-BTTri (90 kJ/mol) [33], mmen-Mg 2 (dobpdc) (71 kJ/mol) [34], CD-MOF-2 (67.2 kJ/mol) [35], MOF-808-Gly (46 kJ/mol) [36], Mg-MOF-74 (47 kJ/mol) [37], Zeolite 13X (44~54 kJ/mol), SIFSIX-3-Zn (45 kJ/mol) [28], FJUT-3 (41.7 kJ/mol) [38], TiFSIX-Cu-TPA (39.2 kJ/mol) [19], CALF-20 (38.4 kJ/mol) [32], dptz-CuTiF 6 (38.2 kJ/mol) [21], Mg-gallate (37 kJ/mol) [27], FJUT-4 (35.2 kJ/mol) [29], dptz-CuGeF 6 (30.3 kJ/mol) [30], etc. This low Q st value would largely reduce the regeneration energy cost.…”

A (4,6)-c copper–organic framework constructed from triazole-inserted dicarboxylate linker with CO2 selective adsorption

“…4). Prominently, the CO 2 /N 2 selectivity of Cu-TZDB at 298 K is higher than many well-known MOF materials, such as SIFSIX-2-Cu-i 12 ( S = 140), HKUST-1 7 ( S = 101), ZJNU-29 35 (93.6), NJU-Bai21 36 ( S = 91), ZnMOF-74 37 (87.7), LIFM-11(Cu) 38 (81.9), FJUT-4 39 (69.3), UTSA-85a 40 (62.5), Y-bptc 41 (62), ZIF-78 9,37 (41.4), HNUST-1 42 ( S = 39.8), and SYSU 43 ( S = 34.2) etc. , slightly lower than Mg-MOF-74 16 ( S = 182.1), but still lower than some famous MOFs of SIFSIX-3-Zn 12 (1818), NJU-Bai52 44 ( S = 581), Zn 2 (bpdc) 2 (bpee) 45 ( S = 493.8), mmen-CuBTTri 14 ( S = 327), and UTSA-16 15 ( S = 314.7) (Table S2†).…”