https://doi.org/10.3390/nano11123348
“The CO2 adsorption data of as-prepared materials over N2 are presented in Figure 4 and Table 3. As can be seen from Table 3, the CO2 adsorption capacity of MIP-207-NH2-25% was up to 3.96 and 2.91 mmol g−1 at 0 and 25 °C, which means an improvement of 20.7% and 43.3% compared with the pure MIP-207, respectively. Moreover, the CO2 capture performance of MIP-207-NH2-25% outperforms most reported amine-modified MOF CO2 adsorbents (Table 3). Similarly, the CO2 adsorption capacity of MIP-207-NH2-50% was higher than that of the unmodified MIP-207. The increase of CO2 adsorption capacity is mainly due to the amine-grafted MIP-207 materials with a high specific area (Figure S6) and many Lewis basic sites (LBS), which greatly enhance their affinity for CO2 [36,37]. Unfortunately, as the added exchange ligand 5-NH2-H2IPA went above 50%, the CO2 working capacity in the MIP-207-NH2-60% adsorbent sharply decreased. One reasonable explanation is that excess 5-NH2-H2IPA slows down the rate of the crystal nucleation formation of MIP-207 and disturbs the self-assembly process. When the ligand reactant is completely 5-NH2-H2IPA, the resulting product cannot even form the original crystal nucleus structure of MIP-207. It can be seen that the adsorption performance is a result of both the adsorption sites and the spatial framework of materials.”
“Figure 4. CO2 and N2 adsorption and desorption isotherms at (a) 0 °C and (b) 25 °C.”
| Materials | Surface Area (m2 g−1) | CO2 Uptake at Testing Condition | CO2/N2 (CO) Selectivity | Qst (kJ mol−1) | Ref. |
|---|---|---|---|---|---|
| MIP-207 | 563 | 3.28/2.03 mmol g−1 @ 0/25 °C and 1 bar | 59 | – | This work |
| MIP-207-NH2-15% | 576 | 3.12/2.21 mmol g−1 @ 0/25 °C and 1 bar | – | 30–35 | This work |
| MIP-207-NH2-25% | 735 | 3.96/2.91 mmol g−1 @ 0/25 °C and 1 bar | 77 | 30–35 | This work |
| MIP-207-NH2-50% | 654 | 3.49/2.36 mmol g−1 @ 0/25 °C and 1 bar | – | 30–35 | This work |
| MIP-207-NH2-60% | 435 | 2.02/1.04 mmol g−1 @ 0/25 °C and 1 bar | – | 30–35 | This work |
| ZIF-8 (40) | 844 | 0.11 mmol g−1 @ 45 °C and 0.15 bar | – | 55 | [19] |
| ED@Cu3(BTC)2-1 | 444 | 4.28/2.15 mmol g−1 @ 0/25 °C and 1 bar | 21.5 | 39 | [29] |
| ED@Cu3(BTC)2-2 | 163 | 1.03/0.54 mmol g−1 @ 0/and 1 bar | 2.68 | – | [29] |
| MAF-23 | – | 2.5 mmol g−1 @ 25 °C and 1 bar | 87 | 34.9 ± 0.9 | [38] |
| ED@MIL-101 | 1584.6 | 3.93/1.93 mmol g−1 @ 0/25 °C and 1 bar | 17.3 | – | [32] |
| TEDA@MIL-101 | 1806.9 | 3.81/1.65 mmol g−1 @ 0/25 °C and 1 bar | 15.5 | – | [32] |
| MIL-101(Cr)-NH2 | 2800 ± 200 | 3.4 mmol g−1 @ 15 °C and 1 bar | 26.5 | 54.6 | [31] |
| PM24@MOF | 2550 | 2.9 mmol g−1 @ 0/25 °C and 1 bar | 84 | 84 | [39] |
| R-PM24@MOF | 2410 | 3.6 mmol g−1 @ 0/25 °C and 1 bar | 143 | 50 | [39] |