Chemically Stable Hafnium-Based Metal-Organic Framework for Highly Efficient C₂H₆/C₂H₄ Separation under Humid...

Realization of ethane-selective porous materials for efficient ethane/ethylene (C₂H₆/C₂H₄) separation is an important task in the petrochemical industry. Although a number of C₂H₆-selective adsorbents have been realized, their adsorption capacity and selectivity might be mostly dampened under humid conditions due to structure decomposition or co-adsorption of water vapor. A desired material should have simultaneously high C₂H₆ uptake and selectivity, excellent water stability, and ultralow water adsorption uptake for industrial applications, but such a material is elusive. Herein, we report a chemically stable hafnium-based material (Hf)DUT-52a, featuring the suitable pore apertures and less hydrophilicity for highly efficient C₂H₆/C₂H₄ separation under humid conditions. Gas sorption results reveal that (Hf)DUT-52a exhibits both high ethane adsorption capacity (4.02 mmol g^-1) and C₂H₆/C₂H₄ selectivity (1.9) at 296 K and 1 bar, which are comparable to the majority of the top-performing materials. Most importantly, the less pore hydrophilicity enables (Hf)DUT-52a to exhibit a negligible water uptake of 0.036 g g^-1 before 40% relative humidity (RH), effectively minimizing the impact of humidity on separation capacity. This material thus shows excellent separation capacity even under 40% RH with a high polymer-grade ethylene production capacity up to 8.43 L kg^-1 at ambient conditions, as evidenced by the breakthrough experiments.