Efficient adsorption separation of xylene isomers in zeolitic imidazolate framework-67@MCF hybrid materials

Abstract

Metal-organic frameworks (MOFs) with metal-containing secondary building units and organic linkers have great potential for the separation of isomers. A type of hybridized materials synthesized by in-situ growth of microporous zeolite imidazolate framework (ZIF-67) on siliceous mesoporous foam (MCF), ZIF-67@MCF, was synthesized and employed in the adsorption separation processes of the petrochemical industry. This study aims to present the adsorption behavior of ZIF-67@MCF for separating xylene isomers. The adsorption separation of xylene isomers on ZIF-67@MCF hybrid materials was studied using the batch vapor-phase adsorption, and liquid-phase breakthrough adsorption. ZIF-67@MCF showed a preferable adsorption of p-xylene over the other two isomers, with the adsorption strength order of p-xylene (pX) ​> ​m-xylene (mX) ​> ​o-xylene (oX). In addition, the adsorption capacity of ZIF-67@MCF materials were studied with the different mole ratio of fluorine to silicon (F/Si ​= ​0, 0.03, 0.06). The higher resolution and larger separation factors for pX/oX and mX/oX, and higher adsorption capacity make ZIF-67@MCF an efficient and reliable alternative adsorbent to the isolation protocols for xylene isomers in the petrochemical industry.