Potential of a pH-Stable Microporous MOF for C₂H₂/C₂H₄ and C₂H₂/CO₂ Gas Separations under Ambient Conditions

Abstract

Cost-effective adsorption-based C 2 H 2 /C 2 H 4 and C 2 H 2 / CO 2 gas separations are extremely important in the industry. Herein, a pH-stable three-dimensional (3D) metal−organic framework (MOF), IITKGP-25, possessing exposed functional sites is presented, which facilitates such separations with excellent ideal adsorbed solution theory (IAST) selectivity (4.61 for C 2 H 2 /C 2 H 4 and 3.93 for C 2 H 2 / CO 2 ) under ambient conditions (295 K, 100 kPa, 50:50 gas mixtures) and a moderate affinity toward C 2 H 2 (26.6 kJ mol −1 ). Interestingly, IITKGP-25 can maintain structural integrity in water and in aqueous acidic/alkaline (pH = 2−10) medium because of the higher coordination numbers around the metal center and the hydrophobicity of the ligand. The adsorption capacity for C 2 H 2 remains unchanged for a minimum of up to five consecutive cycles and 15 days of exposure to 97% relative humidity, which are the prerequisites of an adsorbent for practical gas separation application. Density functional theory (DFT) calculations reveal that the open Cd(II) sites and carboxylate oxygen-coordinated Cd(II) corner of the triangle-shaped onedimensional (1D) channel are the enthalpically more preferred binding sites for C 2 H 2 , which stabilize the adsorbed C 2 H 2 through nonlocal stronger H-bonding and also pπ−dπ and CH−π interactions.

Coordination Unsaturation and Basic Site-Immobilized Nanochannel in a Chemorobust MOF for 3-Fold-Increased High-Temperature Selectivity and Fixation of CO2 under Mild Conditions with Nanomolar Recognition of Roxarsone

“…Given that the activated MOF revealed negligible N 2 uptake at 77 K (Figure S6a), we conducted CO 2 adsorption at 195 K to gain knowledge on porosity. An uptake value of 77.6 cm 3 /g (Figure S6b) relates to the Brunauer–Emmett–Teller (BET) surface area of 216 m 2 /g . Based on appreciable CO 2 adsorption, we next quested the CO 2 , CH 4 , and N 2 adsorption potential of 15a up to 1.0 bar pressure at different temperatures.…”

“…An uptake value of 77.6 cm 3 /g (Figure S6b) relates to the Brunauer−Emmett−Teller (BET) surface area of 216 m 2 /g. 41 Based on appreciable CO 2 adsorption, we next quested the CO 2 , CH 4 , and N 2 adsorption potential of 15a up to 1.0 bar pressure at different temperatures. As shown in Figure 3, the uptake amounts for CO 2 are 59.2, 41.8, and 30.2 cm 3 /g at 273, 298, and 313 K, respectively; which are comparable to some of the recently functionalized MOFs (Figure 5a and Table S3).…”

A linker conformation induced metal–organic framework with high stability and efficient upgrading of natural gas

“…The resistance toward strong bases/acids is noteworthy: GNU-1 is comparable to the previously reported famous NU-1000, 41 JLU-MOF66, 42 IITKGP-25, etc. 43 Furthermore, to determine the thermal stability, thermogravimetric analysis (TGA) was performed under a N 2 atmosphere (Fig. S3†).…”

Carboxamide functionality grafted entangled Co(ii) framework as a unique hydrogen-bond-donor catalyst in solvent-free tandem deacetalization-Knoevenagel condensation with pore-fitting-mediated size-selectivity

“…S6b †), which relates to a BET surface area of 324 m 2 g −1 . 38 Solvent-free tandem deacetalization-Knoevenagel condensation…”