The modulation of ethane‐selective adsorption performance in series of bimetal PCN‐250 metal–organic frameworks: Impact of metal composition

Abstract

The developments of high‐performance adsorbents have attracted ever‐increasing attention in the separation of ethane/ethylene (C2H6/C2H4) mixtures. In this work, a series of ultra‐stable C2H6‐selective metal–organic frameworks (MOFs), PCN‐250, and its bimetal version PCN‐250(Fe2M2+, M2+ = Ni2+, Co2+, Zn2+, Mn2+), were synthesized to investigate the influence of metal compositions on the C2H6‐selective performance. Among the five materials, at 298 K and 100 kPa, PCN‐250(Fe2Co) showed the largest C2H6 uptake (6.21 mmol/g) while PCN‐250(Fe2Zn) exhibited the highest C2H6/C2H4 ideal adsorption solution theory (IAST) selectivity (1.70). The molecular simulation revealed that the introduced metal ions have different influences on the atomic partial charge within the framework which varied the framework adsorption affinities toward C2H6/C2H4 molecules. Moreover, the research on PCN‐250(Fe2Zn) suggested that the increased positive partial charge of metal sites together with a decreased charge density of benzene ring (BR) sites from the organic ligands will be beneficial to improve the desired C2H6 selectivity.

Boosting C2H6/C2H4 separation in scalable metal‐organic frameworks through pore engineering

“…After a single breakthrough experiment, high-grade C 2 H 4 was collected, and the productivity of Cu-cam-pyz, Co-cam-pyz, Cu-cam-dabco, and Ni-cam-pyz were calculated to be 8.87, 4.84, 4.35, and 3.13 L kg À1 , respectively. The maximum working capacity of 8.87 L kg À1 for Cu-cam-pyz is comparable to those of some excellent MOFs, such as PCN-250(Fe 2 Zn) (9.0 L kg À1 ) 36 and MIL-53-NDCA (11.2 L kg À1 ), 39 and is higher than those of Cu(Qc) 2 (4.26 L kg À1 ) 23 and MAF-49 (6.85 L kg À1 ), 24 but falls below that of the best-performing MOF Fe 2 (O 2 )(dobdc) (19.32 L kg À1 ). 10 To summarize, compared with M-cam-apyz and M-cam-dabco, M-cam-pyz exhibits better dynamic C 2 H 6 adsorption uptake, a longer separation time, a higher separation factor, and greater productivity.…”

“…To evaluate the separation selectivity using a C 2 H 6 /C 2 H 4 mixture, calculations based on ideal adsorbed solution theory (IAST) 32 were performed on both 1/99, 10/90, and 50/50 C 2 H 6 /C 2 H 4 mixtures at 101 kPa and 298 K (Figures S12–S15). 33 Cu‐cam‐dabco exhibited the highest C 2 H 6 /C 2 H 4 (50/50) selectivity (2.3) among the MOF materials examined in this work (Figure 4A), and this selectivity was higher than those of ZJNU‐115 (1.56), 34 ZIF‐7 (1.5), 35 IRMOF‐8 (1.6), 26 ZJU‐30 (1.7), 21 PCN‐250 (1.9), 36 and MUF‐15 (1.96), 37 comparable to those of UIO‐66‐2CF 3 (2.54), 27 and MAF‐49 (2.7), 24 but significantly lower than those of NIIC‐20‐Bu (15.4), 20 Fe 2 (O 2 )(dobdc) (4.4), 10 and Cu(Qc) 2 (3.4) 23 . Among M‐cam‐L materials with the same metal center, the order of selectivity was found to be M‐cam‐dabco > M‐cam‐pyz > M‐cam‐apyz.…”

“…(1.7), 21 PCN-250 (1.9), 36 and MUF-15 (1.96), 37 comparable to those of UIO-66-2CF 3 (2.54), 27 and MAF-49 (2.7), 24 but significantly lower than those of NIIC-20-Bu (15.4), 20 Fe 2 (O 2 )(dobdc) (4.4), 10 and Cu(Qc) 2 (3.4). 23 Among M-cam-L materials with the same metal center, the order of selectivity was found to be M-cam-dabco > M-cam-pyz > M-cam-apyz.…”

Hydrophobicity regulation by a facial bromine substitution in MIL‐47(V) for highly selective adsorptive desulfurization

“…The DFT calculations were carried out on Material Studio 2019 27 . The geometry structures of DBT, H 2 O, 2‐bromoterephthalic acid (PTA‐Br), 2‐bromoterephthalic acid (PTA‐Cl), 2‐fluoro‐terephthalic acid (PTA‐F), MIL‐47‐Br fragment and MIL‐47 fragment were optimized by the DMol3 module 28 .…”

“…The DFT calculations were carried out on Material Studio 2019. 27 The geometry structures of DBT, H 2 O, 2-bromoterephthalic acid (PTA-Br), 2-bromoterephthalic acid (PTA-Cl), 2-fluoro-terephthalic acid (PTA-F), MIL-47-Br fragment and MIL-47 fragment were optimized by the DMol3 module. 28 The D2 method of Grimme (DFT-D) was adopted to calculate the binding energies (BEs) between PTA-X linkers (X = non, F, Cl, and Br) or MIL-47-Br fragments with H 2 O or DBT, respectively, according to Equation ( 9).…”