Post-synthetic modification of MOF UiO-66-NH₂ membranes for efficient methanol/organic separation

Abstract

The separation of MeOH/organic mixtures poses a significant challenge in the chemical industry. In this study, metal-organic framework UiO-66-NH₂ membranes prepared by a secondary solvothermal method were employed for MeOH/DMC, MeOH/Tol and MeOH/MTBE separation. The membrane performance was significantly boosted by post-synthetic modification with oxalyl chloride (OC), succinyl chloride (SC), and salicylaldehyde (SA). The modified UiO-66-NH₂-OC and UiO-66-NH₂-SC membranes displayed simultaneous improvement of the separation factors and MeOH fluxes. The modified UiO-66-NH₂-SA membranes exhibited an order of magnitude enhancement of separation factors, with comparable MeOH fluxes. Specifically, separation factors of 3220 and 28,000 with MeOH fluxes of 1.18 kg m⁻² h⁻¹and 1.03 kg m⁻² h⁻¹ for 5/95 wt% MeOH/Tol and 5/95 wt% MeOH/MTBE separation at 40 °C, respectively, were delivered by UiO-66-NH₂-SA membranes. Moreover, the UiO-66-NH₂-SA membranes demonstrated good stability over 120 h's evaluation. This study offers a promising post-synthetic approach and a class of membrane materials for efficient MeOH/organic separation.