A Chemically Stable Hofmann‐Type Metal−Organic Framework with Sandwich‐Like Binding Sites for Benchmark Acetylene Capture

Abstract

The realization of porous materials for highly selective separation of acetylene (C2H2) from various other gases (e.g., carbon dioxide and ethylene) by adsorption is of prime importance but challenging in the petrochemical industry. Herein, a chemically stable Hofmann‐type metal−organic framework (MOF), Co(pyz)[Ni(CN)4] (termed as ZJU‐74a), that features sandwich‐like binding sites for benchmark C2H2 capture and separation is reported. Gas sorption isotherms reveal that ZJU‐74a exhibits by far the record C2H2 capture capacity (49 cm3 g−1 at 0.01 bar and 296 K) and thus ultrahigh selectivity for C2H2/CO2 (36.5), C2H2/C2H4 (24.2), and C2H2/CH4 (1312.9) separation at ambient conditions, respectively, of which the C2H2/CO2 selectivity is the highest among all the robust MOFs reported so far. Theoretical calculations indicate that the oppositely adjacent nickel(II) centers together with cyanide groups from different layers in ZJU‐74a can construct a sandwich‐type adsorption site to offer dually strong and cooperative interactions for the C2H2 molecule, thus leading to its ultrahigh C2H2 capture capacity and selectivities. The exceptional separation performance of ZJU‐74a is confirmed by both simulated and experimental breakthrough curves for 50/50 (v/v) C2H2/CO2, 1/99 C2H2/C2H4, and 50/50 C2H2/CH4 mixtures under ambient conditions.

Recent advances in process engineering and upcoming applications of metal–organic frameworks

“…The purification of acetylene (C 2 H 2 ) gas from natural gas such as CO 2 , CH 4 is of great interest due to its industrial utility. With this attention, J. Pei and coworkers reported that Hofmann based metal–organic framework (named as Co(pyz)[Ni(CN) 4 ], pyz = pyrazine; ZJU-74) shows selective separation of acetylene over CO 2 , C 2 H 4 and CH 4 at ambient conditions [200] . Interestingly, the material possesses high C 2 H 2 capturing capacity (49 cm 3 g −1 at 0.01 bar and 296 K) and high selectivity over CO 2 (36.5 cm 3 g −1 at 1 bar, 296 K), which is the highest selectivity so far.…”

New Supercage Metal–Organic Framework Based on Allopurinol Ligands Showing Acetylene Storage and Separation

“…[1,2] C 2 H 2 is produced primarily from methane( CH 4 )t hermal pyrolysis or hydrocarbon cracking, whichu sually coexists with some carbond ioxide (CO 2 )a nd CH 4 molecules. [3][4][5] This fact makes the separation of C 2 H 2 from C 2 H 2 and CO 2 or C 2 H 2 and CH 4 very importanti nC 2 H 2 industry.C urrent C 2 H 2 separation technology mainly relieso nt raditional refrigerant distillation. But for C 2 H 2 and CO 2 ,d ue to close boilingp oints (C 2 H 2 189.3 K, CO 2 194.7 K), almoste qual size (3.3 3.3 5.7 3 for C 2 H 2 and 3.2 3.3 5.4 3 for CO 2 )a nd identical linear shape, [6,7] the cost and energy consumptionof distillation method are very high.…”

“…[33][34][35] Cage Bc onsists of twenty TDC and eight SBUs, which forms a M 8 L 12 cuboid polyhedron with the void dimensions of ca. 15.7 12.8 9.2 3 (Figure 2b). Cage Cr esultsf rom the interlinkage between two MBBs and four TDC, which produces an M 8 L 10 subunit with the cavity sizes of ca.…”

Metrics for Evaluation and Screening of Metal–Organic Frameworks for Applications in Mixture Separations

“…A number of recently developed MOFs offer the potential of use in adsorptive separations of C 2 H 2 /CO 2 mixtures. 40 − 53 …”