Zr-MOFs-incorporated thin film nanocomposite Pebax 1657 membranes dip-coated on polymethylpentyne layer for efficient separation of CO2/CH4

Abstract

Using thin film nanocomposite (TFN) membranes is an effective method to obtain high CO₂/CH₄ separation performance as compared to traditional mixed matrix membranes (MMMs). In this study, high CO₂ permeable TFN membranes comprising coated Pebax as a CO₂-philic layer filled with Zr-MOFs over the highly permeable polymethylpentene (PMP) support with substantial free volume and desired thermal stability were fabricated to achieve efficient CO₂/CH₄ separation. A series of pure CO₂ and CH₄ gas permeation tests were carried out to evaluate the influence of Zr-MOFs on the gas transport properties of the as-synthesized TFN membranes. The use of amine-functionalized UiO-66 intensified the interaction between the polymer phase and embedded MOFs that led to improvement in the CO₂/CH₄ selectivity. The results obtained from FESEM and TGA/DSC analyses confirmed that the TFN membranes showed superior compatibility between the polymer and filler without non-selective voids at the polymer/filler interface. Moreover, the pure gas separation performance of the TFN membranes was examined under various feed pressures within the range of 2–7 bar. The CO₂/CH₄ separation improved as the feed pressure increased, such that the CO₂ permeability of 393.8 barrer and CO₂/CH₄ selectivity of 39.8 were achieved for TFN membranes containing 1.5 wt% UiO-66-NH₂ at a feed pressure of 7 bar. Further, the mixed gas separation experiments revealed reasonable CO₂ permeability and CO₂/CH₄ selectivity for TFN membranes under both dry and humid conditions.