Preparation and characterization of Ag+ ion-exchanged zeolite-Matrimid(R)5218 mixed matrix membrane for CO2/CH4 separation

摘要

In this work,the zeolite-Y was ion-exchanged by introducing silver cations into the framework of microsized nano-porous sodium zeolite-Y using a liquid-phase ion exchanged method.The Ag+ ion-exchanged zeolite,was then embedded into the Matrimid(R)5218 matrix to form novel mixed matrix membranes (MMMs).The particles and MMMs were characterized by ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS),N2 adsorption-desorption isotherm,X-ray diffraction (XRD),Fourier transform infrared (FTIR) and scanning electron microscopy (SEM).Furthermore,the effects of filler content (0-20 wt％) on pure and mixed gas experiments,feed pressure (2-20 bar) and operating temperature (35-75 C)on CO2/CH4 transport properties of Matrimid/AgY MMMs were considered.Characterization results confirmed an appropriate ion-exchange treatment of the zeolites.The SEM results confirmed the superior interfacial adhesion between polymer and zeolites,particularly in the case of Matrimid/AgY membranes.This is due to the proper silverous zeolite/Matrimid functional groups' interactions.The gas permeation results showed that the CO2 permeability increased about 123％,from 8.34 Barrer for pure Matrimid to 18.62 Barrer for Matrimid/AgY (15 wt％).The CO2/CH4 selectivity was improved about 66％,from 36.3 for Matrimid to 60.1 for Matrimid/AgY (15 wt％).The privileged gas separation performance of Matrimid/AgY (15 wt％) was the result of a combined effect of facilitated transport mechanism of Ag+ ions as well as the intrinsic surface diffusion mechanism of Y-type zeolite.In order to survey the possibility of using the developed MMMs in industry,the CO2-induced plasticization effect and mixed gas experiment were accomplished.It was deduced that the fabricated MMMs could maintain the superior performance in actual operating conditions.