A robust aluminum-based metal-organic framework with [Al8(μ2-OH)8(COO)12] clusters for purification of C2H4 from C2H6/C2H4 mixture

A robust Al-MOF built from octanuclear [Al 8 (μ 2 -OH) 8 (COO) 12 ] clusters with oxygen-rich 1D channels has been prepared. • It exhibits a high C₂H₆ uptake of 147.6 cm 3 /g and an IAST selectivity of 1.69 for equimolar C 2 H 6 /C 2 H 4 at 298 K and 1 bar. • The separation potential (ΔQ = 1.42 mmol/g) outperforms many reported Al-MOFs, reflecting a balanced capacity–selectivity trade-off. • Combined GCMC, DFT, and MD simulations reveal that multiple C–H···O contacts and greater charge transfer govern the ethane preference. The separation of ethane (C 2 H 6 ) from ethylene (C 2 H 4 ) represents a critically important yet highly challenging process in the petrochemical industry, as these two hydrocarbons possess nearly identical molecular sizes and boiling points. In this work, we report the C 2 H 6 adsorption and separation performance of a three-dimensional aluminum-based metal–organic framework (Al-MOF) constructed from octanuclear aluminum clusters and a tricarboxylate linker, featuring one-dimensional channels decorated with abundant strongly electronegative oxygen atoms originating from coordinated formate groups and μ 3 -OH moieties. The presence of these electron-rich oxygen sites creates a polar pore environment that establishes multiple C–H···O short interactions with C 2 H 6 molecules, thereby imparting a distinct recognition preference toward the paraffin over the olefin. Upon activation, the material exhibits a C 2 H 6 adsorption capacity of 147.6 cm 3 /g at 298 K and 1 bar. The ideal adsorbed solution theory (IAST) selectivity for an C 2 H 6 /C 2 H 4 (10/90) mixture reaches 1.69 at 298 K and 1 bar. Furthermore, the separation potential (Δ Q ), which integrates both adsorption capacity and selectivity, is determined to be 1.42 mmol/g, indicating a well-balanced performance profile. The different adsorption performance of 1a toward C 2 H 6 /C 2 H 4 was thoroughly studied via a combination of GCMC, DFT and MD calculations, which demonstrates that deliberate introduction of electron-rich oxygen functionalities into the pore walls of Al-MOFs represents an effective strategy for enhancing ethane-selective adsorption, positioning the present material as a competitive candidate for energy-efficient ethylene purification. Graphical -Synopsis A robust Al-MOF with octanuclear clusters and oxygen-rich pore walls was synthesized for C 2 H 6 /C 2 H 4 separation. It exhibits preferential C₂H₆ adsorption (147.6 cm 3 /g at 298 K, 1 bar), an IAST selectivity of 1.69 for equimolar mixtures, and a separation potential of 1.42 mmol/g. Combined GCMC, DFT, and MD simulations reveal that stronger C–H···O hydrogen bonding and greater charge difference lead to a more favorable host–guest interaction energy (–1.34 vs. –1.27 eV) for ethane. This work demonstrates that engineering electronegative oxygen sites in Al-MOFs is an effective strategy for energy-efficient ethylene purification. Graphical -Pictogram Download: Download high-res image (322KB) Download: Download full-size image