Functionalized Metal-organic Frameworks: Promising Porous Materials for Chemical Separation

Abstract

The exigent usage of highly energy intensive routes such as, large distillation columns, azeotropic and extractive distillation methods has propelled the need for new-generation tailored adsorbent materials such as, pre-functionalized MOFs. These can act as superior host materials to manifest highly selective and recyclable sorption performance for particularly one of the azeotropic components among a pair (or more) of hydrocarbon adsorbates. In general, to circumvent energy-intensive separation routes hitherto adopted, such a new approach of harnessing designed functionalized MOFs may indeed prove significant in terms of developing coherent insights aimed at greener, energy-friendly scenario of industrially relevant aliphatic and aromatic hydrocarbon species’ separation. Moreover, to tackle omnipresent major environmental issues such as marine oil spillages, efficient oil/water separation performance with high oil absorption capacity and recyclability attributes are the cornerstone components pursued for serving the application frontiers. Under this backdrop, appropriately fabricated polymer membranes based on highly hydrophobic and oleophilic MOF sorbents are of marked relevance. We have developed new strategies for achieving the aforementioned multiple separation performances, which seem reasonably promising from the energy and environmental standpoint of industrial hydrocarbon vapour separation and oil/water separation. Following a flexible di-ether node based linker functionalization rationale, dual adsorptive separation performances of p-xylene and styrene over their congener C8-alkylaromatic isomeric species have been manifested by the ensuing dynamic MOF. Selective sorption of benzene over cyclohexane (C6-azeotropes) has also been materialized by two different coherent approaches. While the first one is derived from electron-deficient pore functionalization approach stemming from the novel employment of diaminotriazine linker, the other one is entirely consequent of a tactical exploitation of the coordinatively unsaturated metal sites functionalizing the microporous MOF channel. Finally, a recyclable composite material based on a first-of-its-kind ultrahydrophobic fluorinated MOF has been synthesized, which has emerged as an excellent oil/water separating membrane material.