Mixed Metal–Organic Framework with Multiple Binding Sites for Efficient C₂H₂/CO₂Separation

Abstract

The separation of C2H2/CO2 is particularly challenging owing to their similarities in physical properties and molecular sizes. Reported here is a mixed metal–organic framework (M′MOF), [Fe(pyz)Ni(CN)4] (FeNi‐M′MOF, pyz=pyrazine), with multiple functional sites and compact one‐dimensional channels of about 4.0 Å for C2H2/CO2 separation. This MOF shows not only a remarkable volumetric C2H2 uptake of 133 cm3 cm−3, but also an excellent C2H2/CO2 selectivity of 24 under ambient conditions, resulting in the second highest C2H2‐capture amount of 4.54 mol L−1, thus outperforming most previous benchmark materials. The separation performance of this material is driven by π–π stacking and multiple intermolecular interactions between C2H2 molecules and the binding sites of FeNi‐M′MOF. This material can be facilely synthesized at room temperature and is water stable, highlighting FeNi‐M′MOF as a promising material for C2H2/CO2 separation.

Selective capture of carbon dioxide from hydrocarbons using a metal-organic framework

“…This is comparable to [Cd 2 L(H 2 O)] (42.9) 34 and exceeded by only one other reported material (SIFSIX-14-Cu-i, 85) (Supplementary Table 10) 35 . Typical physisorbents show a preference for unsaturated hydrocarbons over CO 2 , especially when bonding between the guest's π electrons and open metal sites can occur 25,[36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] . However, MUF-16 exhibits a uniform preference for CO 2 over all C2 and C3 hydrocarbons at 293 K and 1 bar (Table 1).…”

An Isomeric Copper‐Diisophthalate Framework Platform for Storage and Purification of C2H2and Exploration of the Positional Effect of the Methyl Group

“…At the pressure of 1 atm and 298 K, the C 2 H 2 /CH 4 and C 2 H 2 /CO 2 uptake capacity ratio reaches 8.7 and 2.03 for ZJNU‐94 , 8.5 and 2.02 for ZJNU‐95 and 9.2 and 2.07 for ZJNU‐96 . The ratio of C 2 H 2 vs. CO 2 uptake surpasses those of some literature MOFs reported for C 2 H 2 /CO 2 separation, such as DICRO‐4‐Ni‐i (1.87), [25] ZJNU‐100 (1.79), [26] BSF‐3‐Co (1.67), [27] JXNU‐5 (1.61), [28] FeNi‐M'MOF (1.58), [29] UTSA‐74 (1.53), [30] Cu‐CPAH (1.50), [31] TCuCl (1.50), [32] UTSA‐50 (1.41), [33] SNNU‐45 (1.38), [11c] ZJNU‐13 (1.35), [11a] ZJU‐74 (1.29), [34] JNU‐1 (1.24), [35] MUF‐17 (1.20), [36] NKMOF‐1 (1.19), [37] and FJU‐22 (1.03) [38] . To assess the separation feasibility, we employed the ideal adsorbed solution theory (IAST) model [39] to forecast the adsorption selectivity.…”

“…Next, to investigate their potential for C 2 H 2 separation and purification, pure-component CO 2 and CH 4 isotherm data were also collected and presented together with the corresponding C 2 H 2 adsorption data in the same figure for comparison (Figure 2c-e [25] ZJNU-100 (1.79), [26] BSF-3-Co (1.67), [27] JXNU-5 (1.61), [28] FeNi-M'MOF (1.58), [29] UTSA-74 (1.53), [30] Cu-CPAH (1.50), [31] TCuCl (1.50), [32] UTSA-50 (1.41), [33] SNNU-45 (1.38), [11c] ZJNU-13 (1.35), [11a] ZJU-74 (1.29), [34] JNU-1 (1.24), [35] MUF-17 (1.20), [36] NKMOF-1 (1.19), [37] and FJU-22 (1.03). [38] To assess the separation feasibility, we employed the ideal adsorbed solution theory (IAST) model [39] to forecast the adsorption selectivity.…”

Impact of Pore Size and Defects on the Selective Adsorption of Acetylene in Alkyne‐Functionalized Nickel(II)‐Pyrazolate‐Based MOFs

“…The higher Q st values for C 2 H 2 over CO 2 on [Ni 8 (L 4 ) 6 ] and [Ni 8 (L 5 ) 6 ] systems can explain the observed selectivity towards C 2 H 2 . As illustrated in Figures S10 and S11, by increasing the pressure value, the Q st value decreases, which can be attributed to the weaker interaction between the adsorbates and the adsorbents as a consequence of the covering of the most active adsorption sites on the pore surface [23,24] . Noteworthy, the Q st values for the C 2 H 2 are slightly modified upon the creation of defects with a small decrease for [Ni 8 (L 4 ) 6 ]@K and a small increase for [Ni 8 (L 5 ) 6 ]@K. By contrast, the Q st values for the CO 2 increase significantly upon the creation of defects (Table 1 and Figures S10, S11).…”