Research On Properties Of Supported Des Membrane For Separation Of Ethylene/ethane

The industry of ethylene,as the pillar of petrochemical industry,indicates the development level of some countries or area and provides the material and energy for the human's life and industrial production.In the product process of ethylene,the systems of olefin/paraffin always exist,so the mixtures'purifications are necessary.Because the olefin/paraffin with same carbon number show similar physical and chemical properties,the traditional cryogenic distillation cost much in energy and equipment.It is so significant to search a novel olefin/paraffin separation method with high efficient and low cost.Supported liquid membrane used for the gas separation performs easy preparation,high selectivity and high permeation.Deep eutectic solvents?DES?of organic-inorganic mixtures show the atom economy,negligible vapor pressure,designable structure.The copper?I?-based DES used in supported liquid membrane for olefin/paraffin separation can play a role on high content of media,negligible vapor pressure,controllable chemical and physical properties and low cost.In this study,copper?I?-based DES SLM was utilized to separate ethylene/ethane mixtures.Pure and mixed gas permeation experiments were carried out to investigate the influences of ILs composition,trans-membrane pressure,temperature and time upon the separation performance.SEM and ATR-FTIR were used to characterize the SILM's preparation.TOF-MS and RAMAN were performed to define the structure of copper?I?-based DES.Furthermore,the facilitated transport effect was studied by¹H NMR and quantum mechanical calculation.The experiment's results indicated that the permeation changes with the system's viscosity,which first rose and then decreased with the increase of CuCl/[Bmim][Cl]ratio.The permselectivity increased linearly with the increase of the CuCl/[Bmim][Cl]ratio.When the CuCl/[Bmim][Cl]ratio increased to 2:1,the ethylene permeability reached to 2653 barrer and the permselectivity was up to 11.8.This performance surpassed the reported traditional polymeric membrane upper bound with a long-term stability.TOF-MS and RAMAN indicated that copper?I?-based DES was composited of a imidazolium cation and several kinds of Copper?I?chloride acid anionic species and with the increase of the CuCl/[Bmim][Cl]ratio,the anionic species converted from CuCl₂^-to Cu₂Cl₃^-.The results of the molecular simulation show that the anionic species formed by sp hybridization of Cu⁺with Cl^-possesses unfilled attachment sites to selectively complex with C₂H₄ and weakens the interionic hydrogen bond in[Bmim][Cl],thus resulting in the deep eutectic phenomenon.In the complexation between the[Bmim][Cu₂Cl₃]and C₂H₄,only one Cu⁺attachment site practically participates the complexation and the other one hence the complexation by the inductive-conjugation effect.This research put forward an economic and efficient method to separate the olefin/paraffin mixtures and studied deeply in the level of practical application and separation mechanism,which made a contribution for the olefin/paraffin separation.