Preferential Adsorption of CO₂ in an Ultramicroporous MOF with Cavities Lined by Basic Groups and Open-Metal Sites

Abstract

Here, we present a new ultramicroporous Cu paddlewheel based MOF. This ultramicroporous MOF has most of the features such as porosity (BET surface area = 945 m/g), CO capacity (3.5 mmol/g at ambient temperature and pressure), CO/N selectivity (sCO/N = 250), and fast CO diffusion kinetics ( D = 2.25 × 10 m/s), comparable to some of the other high-performing ultramicroporous MOFs, with strong binding sites. Typically, such MOFs exhibit strong CO-framework interactions (evidenced from a heat of adsorption ≥ 38 kJ/mol). However, the MOF explained here, despite having channels lined by the amine and the open-metal sites, possesses only a moderate CO-framework interaction (HOA = 26 kJ/mol). Using periodic DFT, we have probed this counterintuitive observation.

A new approach to enhancing the CO2 capture performance of defective UiO-66 via post-synthetic defect exchange

“…MOF material lined by basic amine groups and the high CO2 uptake was not accompanied by strong adsorbent-adsorbate interactions. 45 It appears that, at the degree of functionalization we achieve, IEA does not change significantly. Invoking acidbase properties also does not help in interpreting the observation: the heterocyclic nitrogen atoms in NA (pKa 4.…”

A microporous, amino acid functionalized Zn(ii)-organic framework nanoflower for selective CO2capture and solvent encapsulation

“…Interestingly, its uptake of CO 2 is higher or comparable with other amine or amino acid based system (Table S1, ESI †). 12,19 On the other hand, the uptake of CH 4 is less compared to CO 2 at 298 K, 273 K, and 263 K, which are 15.1 cm 3 g À1 , 21.2 cm 3 g À1 , and 24.8 cm 3 g À1 , respectively (Fig. 4d).…”

“…These Q st values have been compared with other MOFs (Table S1, ESI †). Interestingly, Zn-CBS shows comparable and higher Q st for CO 2 than MIL-53(Cr) (32 kJ mol À1 ), 20 IRMOF-9-NMe 2 (27 kJ mol À1 ), 21 TEA@bio-MOF-1 (26.5 kJ mol À1 ), 22 CPF-13 (28.3 kJ mol À1 ), 14 JUC-141 (27.85 kJ mol À1 ), 10 IISERP-MOF20 (26 kJ mol À1 ), 12 [Zn(atz) 2 ] (26 kJ mol À1 ), 16 [Zn 2 (BDC) 2 (DABCO)] (25 kJ mol À1 ), 23 NOTT-202a (22 kJ mol À1 ), 24 [Zn 4 (OH) 2 (1,2,4-BTC) 2 ] (20 kJ mol À1 ), 25 and IRMOF-3 (19 kJ mol À1 ). 26 Whereas, the Q st for methane is higher than those reported for the MOFs in the literature, such as, SNU-100 (26.5 kJ mol À1 ), 16 JUC-141 (22.7 kJ mol À1 ), 10 [Zn(atz) 2 ] (19.5 kJ mol À1 ), 16 IITKGP-6 (18.4 kJ mol À1 ), 29 SNU-151 (18.2 kJ mol À1 ), 41 IITKGP-5 (14.8 kJ mol À1 ), 15 SNU-77S (14.3 kJ mol À1 ), 41 and SNU-150 (12.8 kJ mol À1 ).…”

“…These properties play vital roles in various applications, such as gas and vapour adsorption, catalysis, sensing, magnetism, etc. [1][2][3][4][5][6][7][8][9][10][11][12] In particular, their promising roles in carbon capture have received significant attention for an urgent need to reduce the concentration of the major greenhouse gas CO 2 as it is a part of flue gases which has a toxic effect on the environment. 13 Also, the composition of landfill gas has CO 2 along with CH 4 (CO 2 /CH 4 = 50/50) that needs to be separated out, which is essential for natural gas purification.…”

Advances in Post‐Combustion CO2Capture by Physical Adsorption: From Materials Innovation to Separation Practice

“…The orientation of CO 2 molecules in the pores of MOFs was found effective to alter the interaction with guest CO 2 . Nandi et al [198] . revealed that the CO 2 molecules align parallel to the open metal sites of Cu‐MOF and get sandwiched between two open metal sites by GCMC simulations (Figure 19a).…”