Study On Supported Liquid Membrane Based On Novel Deep Eutectic Solvent For The Separation Of Ethylene/ethane

Ethylene is the important raw material of industry.The separation and purification of ethylene still challenges the world.Supported liquid membranes（SLMs）based on deep eutectic solvent,which have the advantages of design flexibility,high performance and energy saving,have exhibited great potential materials for the gas separation.The silver-based DESs,which constructed from Ag CF₃SO₃ and acetamide,and the multifunctional ternary deep eutectic solvent,which constructed from Al（NO₃）₃ with the Ag NO3/methylacetamide（NMA）mixture,were synthetized in this work.The melting point and viscosity of DES were measured.Various spectroscopic characterization and quantum mechanical calculations revealed the formation mechanism and structure of DES,confirming that hydrogen bonding interaction,complexing interaction and electrostatic interaction yielded the stable liquid.The silver ions complexing with C₂H₄ as carriers for the facilitated transport.The complexing interaction between Ag⁺and NMA and the complexing interaction between Al³⁺and NO₃^-weakened the electrostatic interaction between Ag⁺and NO₃^-,and improved the interaction energy between ethylene molecule and carrier.The destruction and reconstruction of hydrogen-bond networks in DESs caused the decrease in the melting point of the mixture relative to the melting points of the individual components,which yielded the homogeneous and stable liquid.The incorporation of a sweetener（Al（NO₃）₃）not only significantly promoted the activity of carriers but also enhanced the long-term stability of DES,which killed two birds with one stone.Moreover,the as-prepared DESs-SLMs were characterized by SEM,AFM and EDS-mapping,while their separation performances were investigated by C₂H₄/C₂H₆separation experiments.The Ag/acetamide-SLMs possessed the excellent permeability of C₂H₄（2730 Barrer）and comparable selectivity of C₂H₄/C₂H₆（64.1）,and the ternary DES-based membranes exhibited high ethylene permeability（Increasing 100%）,ethylene/ethane selectivity（Increasing 103%）and stability,both outperforming majority of the previously published data.The structure-performance of DES-SLM and the optimization of separation process including operational temperature,transmembrane pressure,feed ratio and sweep gas flow rate was investigated.Herein,a supported liquid membrane based on silver-based DES with excellent performance was constructed for the ethylene/ethane separation and the insights into the formation mechanism of silver-based DESs is useful for further design and strengthening.This work will shed light on the design of multifunctional liquid membranes for precise molecular separation.