Desolvation-Degree-Induced Structural Dynamics in a Rigid Cerium–Organic Framework Exhibiting Tandem Purification of Ethylene from Acetylene and Ethane

Abstract

Due to the industrial requirements for high production and high quality of ethylene, efficient purification of ethylene from acetylene and ethane is of prime importance but challenging. Dynamic metal–organic frameworks (MOFs) have demonstrated intriguing structural dynamics and diverse applications recently. Among them, although a few flexible ones have exhibited interesting ethylene purification capability, rigid ones were yet barely investigated for such purpose. In this regard, a cerium­(III)-based MOF was solvothermally synthesized, which is rigid and assembled from rod molecular building blocks associated with coordinative N,N-dimethylformamide (DMF) molecules. After liberating different degrees of DMF ligands via heating under vacuum or acetone exchange, both partially desolvated compounds of Ce-MOF-1 and Ce-MOF-2 were concertedly isolated in a fashion of single-crystal to single-crystal transformation. Although both newly generated materials crystallize in the same space group, they exhibit dissimilar unit cell parameters and slightly distinct ultramicropore sizes and pore microenvironments, thanks to the discrepancy in the desolvation degree. Consequently, Ce-MOF-1 and Ce-MOF-2 individually demonstrate C2H2- and C2H6-selective adsorption behavior, resulting in the potential tandem separation of C2H4 from C2H2 and C2H6 mixtures. The above results were successfully supported by not only single gas adsorption isotherms but also grand canonical Monte Carlo (GCMC) calculation studies and dynamic breakthrough experiments. The present work may pave the way for rigid MOFs aiming at advancing applications via solid-state structural dynamics.

Flexible Microporous Framework for One-Step Acquisition of Ethylene from Ternary C2 Hydrocarbons

“…Driven by the disparities in the adsorption capacities and binding affinities of the framework to C 2 H 2 , C 2 H 4 , and C 2 H 6 , − we further evaluate the separation selectivities for C 2 H 2 /C 2 H 4 and C 2 H 6 /C 2 H 4 with different ratios based on the ideal adsorption solution theory (IAST) (Figure d). For C 2 H 2 /C 2 H 4 (1/99), the selectivity can be up to 2.31 at 1 bar, which is higher than CoMOF-74 (1.70) and MgMOF-74 (2.18), and for C 2 H 2 /C 2 H 4 (50/50), the selectivity can reach 2.47 at 1 bar. , To be more specific, the adsorption selectivities of C 2 H 6 /C 2 H 4 with compositions of 50/50, 10/90, and 1/99 have also been estimated .…”

Tuning Pore Polarization to Boost Ethane/Ethylene Separation Performance in Hydrogen‐Bonded Organic Frameworks

“…The main difference between the two structures is the existence of DMA filled in the channels of the HOF‐NBDA(DMA) framework. Whereas DMA will decompose at high temperature and the resulting Me 2 NH can be removed from the pores by vacuum [41] . Further experiments have been conducted to investigate this possibility.…”

“…Whereas DMA will decompose at high temperature and the resulting Me 2 NH can be removed from the pores by vacuum. [41] Further experiments have been conducted to investigate this possibility. As expected, it was found that the powder X-ray diffraction (PXRD) peaks changed obviously and matched well to the HOF-NBDA pattern when the HOF-NBDA-(DMA) sample was activated by heating in air or under vacuum (Figure S6), which indicated a possible solid-state structural transformation.…”

Tuning the Trade‐Off between Ethane/Ethylene Selectivity and Adsorption Capacity within Isoreticular Microporous Metal−Organic Frameworks by Linker Fine‐Fluorination

“…[4,5] The use of porous solid adsorbent for nonthermally driven purification processes with lower-energy consumption is a promising alternative efficient separation technology. [6][7][8][9][10][11][12][13][14] The separation performance depends on the pore structure and surface property of adsorbent and the physicochemical properties of the adsorbed gases. Compared with zeolite and other porous solid materials, metal−organic frameworks (MOFs) have emerged as viable alternatives with great promise for C 2 H 6 / C 2 H 4 separation owing to their adjustable structures and modulable channel surface functionalization.…”