Preparation and characterization of Ag+ ion-exchanged zeolite-Matrimid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~5218 matrix to form novel mixed matrix membranes(MMMs). The particles and MMMs were characterized by ultraviolet-visible diffuse reflectance spectroscopy(UV–vis DRS), N_2 adsorption–desorption isotherm, X-ray diffraction(XRD), Fourier transform infrared(FTIR) and scanning electron microscopy(SEM). Furthermore, the effects of filler content(0–20wt%) on pure and mixed gas experiments, feed pressure(2–20 bar) and operating temperature(35–75 oC)on CO_2/CH_4 transport properties of Matrimid/Ag Y 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/Ag Y membranes.This is due to the proper silverous zeolite/Matrimid functional groups' interactions. The gas permeation results showed that the CO_2 permeability increased about 123%, from 8.34 Barrer for pure Matrimid to18.62 Barrer for Matrimid/Ag Y(15 wt%). The CO_2/CH_4 selectivity was improved about 66%, from 36.3 for Matrimid to 60.1 for Matrimid/Ag Y(15 wt%). The privileged gas separation performance of Matrimid/Ag Y(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 CO_2-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.