Fine-Tuning the Pore Environment of the Microporous Cu-MOF for High Propylene Storage and Efficient Separation of Light Hydrocarbons

Ethylene (C 2 H 4 ) and propylene (C 3 H 6 ) are important energy sources and raw materials in the chemical industry. Storage and separation of C 2 H 4 and C 3 H 6 are vital to their practical application. Metal-organic frameworks (MOFs) having adjustable structures and pore environments are promising candidates for C 3 H 6 /C 2 H 4 separation. Herein, we obtained a Cu-based MOF synthesized by H 3 TTCA and pyrazine ligands. By adding different functional groups on the ligands within the MOFs, their pore environments are adjusted, and thus, the C 3 H 6 storage capacity and C 3 H 6 /C 2 H 4 separation efficiency are improved. Eventually, the fluoro- and methyl-functionalized iso-MOF-4 exhibits a better gas storage and C 3 H 6 /C 2 H 4 separation performance compared with iso-MOF-1 (nonfunctionalized), iso-MOF-2 (fluoro-functionalized), and iso-MOF-3 (methyl-functionalized). A record-high C 3 H 6 uptake of 293.6 ± 2.3 cm 3 g -1 (273 K, 1 atm) is achieved using iso-MOF-4 . Moreover, iso-MOF-4 shows excellent repeatability, and only 3.5% of C 3 H 6 storage capacities decrease after nine cycles. Employing Grand Canonical Monte Carlo (GCMC) simulations, it is indicated that iso-MOF-4 preferentially adsorbs C 3 H 6 rather than C 2 H 4 at low pressure. Single-crystal X-ray diffraction on C 3 H 6 -adsorbed iso-MOF-4 crystals precisely demonstrates the adsorption positions and arrangement of C 3 H 6 molecules in the framework, which is consistent with the theoretical simulations. Remarkably, gas sorption isotherms, molecular simulations, and breakthrough experiments comprehensively demonstrate that this unique MOF material exhibits highly efficient C 3 H 6 /C 2 H 4 separation. Additionally, iso-MOF-4 also possesses efficient separation of C 3 H 8 /CH 4 and C 2 H 6 /CH 4 , indicating its promising potential in storage/separation of light hydrocarbons in industry.