One-Step Ethylene Purification from Ternary Mixture through Adaptive Recognition Sites

One-step adsorptive purification of ethylene (C2H4) from ternary mixture comprising of acetylene (C2H2), ethylene (C2H4) and carbon dioxide (CO2) is a great challenge in the chemical industry. Herein, a microporous metal-organic framework (FJI-H38) has been reported, which possesses a high density of electronegative O/N binding sites and appropriate pore size. Notably, at 0.01 bar and 298 K FJI-H38 shows excellent trapping capability for C2H2 (1.64 mmol/g) and CO2 (2.33 mmol/g), while the uptake of C2H4 is only 0.41 mmol/g, which endows FJI-H38 high C2H2/C2H4 selectivity and top-level CO2/C2H4 simultaneously. Polymer-grade C2H4 (≥99.95%) with record-high productivity can be successfully obtained from ternary C2H2/CO2/C2H4 mixture in one step under various conditions. Even at 318 K, the separation performance has no obvious decrease. Such excellent separation performance is due to the adaptive recognition of C2H2 and CO2 by FJI-H38 through the synergistic effect of appropriate pore size and the match of electrostatic potentials, where C2H2 and CO2 can be stabilized by the O/N and aromatic ring sites.