Threading MOF membranes with polymer chains for superior benzene/cyclohexane separation

Abstract

High performance membranes for benzene/cyclohexane separation are crucial. Metal–organic frameworks (MOFs), given by their high structural designability, are expected to provide satisfying membrane performance for this separation. In this study, polymer chains were threaded into the pores of MOF UiO-66, to reconstruct the structures of the membrane channels. The permeance of benzene and selectivity of benzene/cyclohexane were boosted simultaneously, compared with the bare UiO-66 membranes. The performance enhancement was rationalized since the solubility of benzene was improved meanwhile the diffusivity of cyclohexane dropped by virtue of the new adsorption sites of benzene and narrower membrane channels created by threading polymers. The as-synthesized polyvinyl alcohol (PVA)-threaded UiO-66 membranes exhibited a benzene permeance around 110 GPU and a benzene/cyclohexane selectivity around 30.