Benchmark C2H2/CO2 and CO2/C2H2 Separation by Two Closely Related Hybrid Ultramicroporous Materials

Abstract

The removal of CO 2 impurities from C 2 H 2 -containing gas mixtures is an important step in purifying C 2 H 2 , a feedstock chemical used in the production of several commodity chemicals. However, that C 2 H 2 and CO 2 exhibit similar size and physicochemical properties makes their separation by physisorption extremely difficult. In this work, we detail how two hybrid ultramicroporous materials (HUMs)-known variant SIFSIX-3-Ni and variant TIFSIX-2-Cu-i-exhibit exceptional CO 2 /C 2 H 2 and C 2 H 2 /CO 2 selectivity, respectively. SIFSIX-3-Ni sets a benchmark for CO 2 /C 2 H 2 selectivity at low partial pressures, whereas TIFSIX-2-Cu-i ranks among the best porous materials in the context of C 2 H 2 / CO 2 selectivity. The performance of these HUMs was confirmed by real-time dynamic breakthrough experiments. To our knowledge, such yin-yang inversion of selectivity in closely related compounds is unprecedented. We attribute this to the distinct sorbate binding sites in SIFSIX-3-Ni and TIFSIX-2-Cu-i, as revealed by modeling studies.

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

“…The C 2 H 2 and CO 2 gas adsorption isotherms of FeNi‐M′MOF were measured at both 273 and 298 K. As shown in Figure b, the volumetric C 2 H 2 uptake capacity of FeNi‐M′MOF is 133 cm 3 cm −3 (4.29 mmol g −1 ) at 1 bar and 298 K, which is higher than those of many other MOFs, such as DICRO‐4‐Ni‐i (52 cm 3 cm −3 ), ZJU‐60 a (96 cm 3 cm −3 ), Cu[Ni(pdt) 2 ] (108 cm 3 cm −3 ), SNNU‐45 (113 cm 3 cm −3 ), TIFSIX‐2‐Cu‐i (116 cm 3 cm −3 ), PCP‐33 (128 cm 3 cm −3 ), and comparable to those of UTSA‐74 (144 cm 3 cm −3 ), FJU‐90 a (146 cm 3 cm −3 ), and Zn‐MOF‐74 (150 cm 3 cm −3 ) . The CO 2 uptake of FeNi‐M′MOF is 84 cm 3 cm −3 (2.72 mmol g −1 ) at 1 bar and 298 K. At 1 bar and 273 K, C 2 H 2 and CO 2 uptakes of FeNi‐M′MOF are up to 145 and 102 cm 3 cm −3 respectively, as shown in Figure S8.…”

Halogen–C2H2 Binding in Ultramicroporous Metal–Organic Frameworks (MOFs) for Benchmark C2H2/CO2 Separation Selectivity

“…S AC (1:1) values at 1 bar were found to be 5.3 ( TCuI ), 9.5 ( TCuBr ), and 16.9 ( TCuCl ) and S AC (2:1) values at 1 bar were found to be 5.2 ( TCuI ), 9.6 ( TCuBr ), and 17.2 ( TCuCl ; Figure S46 in the Supporting Information), an order that correlates with increasing C 2 H 2 sorption kinetics and decreasing BET surface area. As presented in Table S1, under relevant partial pressure, S AC for TCuCl (16) is higher than most of the leading C 2 H 2 ‐capture sorbents, including Zn‐MOF‐74 (4), ZJU‐60 a (6.7), MIL‐100(Fe) (12.5), PCP‐33 (5.6), FJU‐22 a (7.1), UTSA‐74 a (14.3), TIFSIX‐2‐Cu‐i (10), UTSA‐300 a (10), JCM‐1 (13), FJU‐90 a (4.3), JNU‐1 (3), MUF‐17 (6) and ZJUT‐2 a (10) …”

Lock‐and‐Key and Shape‐Memory Effects in an Unconventional Synthetic Path to Magnesium Metal–Organic Frameworks

“…Separation of CO 2 from C 2 H 2 is important in industrial applications but is also challenging due to their similar size and physicochemical properties. [21] It is intriguing to find that CPM-107op can take up 136.7 cm 3 g À1 and 97.5 cm 3 g À1 of C 2 H 2 at 273 Ka nd 298 K( Figure S21), respectively.The uptake capacity at 298 Kishigher than some benchmark C 2 H 2 /CO 2 -separation materials such as UTSA-300 (67 cm 3 g À1 )and HOF-3 (47 cm 3 g À1 ). [22] Theisosteric heat for C 2 H 2 adsorption is also calculated to be in the range of 32-37 kJ mmol À1 ,a pparently larger than that of CO 2 (Figure 4).…”