Utilization of nanoplatelets in organic–inorganic hybrid separation materials: Separation advantages and formation challenges

Abstract

Gas separation demands combined with the need to increase industrial process efficiency have encouraged the use of membranes as attractive alternatives to thermally driven separations. Despite the attractiveness of the membrane platform, intrinsic transport properties of pure polymeric membranes are limited by a tradeoff between productivity and selectivity. This tradeoff can be partially overcome by broadening the spectrum of materials to include hybrid composites (commonly referred to as mixed matrix membranes) of polymer and a dispersed phase of either inorganic or carbon materials. These materials offer processing options that combine the attractive, low cost processing approaches that are already available for the manufacture of pure polymer-based membranes. Hybrid membranes incorporating traditional zeolite materials, with unit aspect ratios ( A r ∼ 1), limit options to create thin selective layers. Recent studies have considered high aspect ratio ( A r > 10) sieving materials ( i.e. flakes or platelets) with significantly higher aspect ratio rather than traditional zeolites. These higher aspect ratios increase the tortuous path of permeation for rejected penetrants, so a low volume fraction of platelet material can be used to produce high performance membranes. In this report we will discuss the advantages of hybrid membranes containing nanoplatelet materials and the challenges associated with creating these advanced materials as well as the unique applications within an asymmetric hollow fiber membrane. We will also report on our initial attempts at producing nanoplatelet-polymer asymmetric hollow fiber membranes.