Ultra-stable copper decorated deep eutectic solvent based supported liquid membranes for olefin/paraffin separation: In-depth study of carrier stability.

Great efforts have been made to develop versatile membranes with carrier-facilitated transport mechanism for olefin/paraffin separation. However, carrier instability has been an overwhelming roadblock, and manufacturing stable membranes have not yet been fulfilled, especially for copper salt-based membranes. Herein, a family of innovative deep eutectic solvents (DESs) were designed by utilizing Brønsted-acidic ammonium salts as hydrogen bond acceptors, which can stabilize CuCl carrier efficaciously. Then, stable copper-decorated deep eutectic solvent based supported liquid membranes (Cu-DESMs) were constructed by confining the as-designed DES and CuCl into porous support for the effective ethylene/ethane separation, where the morphology, molecular interactions and the structure-performance were revealed. The Cu-DESMs exhibited high ethylene permeability of 32.7 Barrer and ethylene/ethane selectivity of 26.8, which far exceeded most of copper salt-based membranes. Particularly, the Cu-DESMs exhibited long-term stability, and the investigation of carrier stability mechanism revealed that deactivation of copper salt-based carriers was included by disproportionation or oxidation reactions, and strong hydrogen-bond interactions and encapsulation effect favored carrier stability. This work offers preliminary guidance for designing stable carrier, and the ultra-stable Cu-DESMs with Brønsted-acidic property will make membrane separation move a step toward practical ethylene/ethane separation. [Display omitted] • Copper-decorated deep eutectic solvent based supported liquid membranes (Cu-DESMs) were constructed to separate ethylene/ethane efficiently. • Brønsted-acidic ammonium salts were used as hydrogen bond acceptor to stabilize CuCl carrier. • Deactivation mechanism of CuCl carrier was revealed and carrier stability strategy was offered. • Strong hydrogen-bond interactions and encapsulation effect favored the carrier stability. • The separation performances of Cu-DESMs could be tailored by the rational molecular design of DESs. [ABSTRACT FROM AUTHOR]