Enhanced gas separation performance of Pebax mixed matrix membranes by incorporating ZIF-8 in situ inserted by multiwalled carbon nanotubes

Abstract

It is imperative to research CO2 separation membrane in terms of the issues of greenhouse gas emission. In this work, zeolitic imidazolate frameworks-8 (ZIF-8) particles in situ inserted by multiwalled carbon tubes (MWCNTs) (MWCNTs@ZIF-8) were embedded into Pebax matrix to fabricate mixed matrix membranes (MMMs). The incorporated ZIF-8 particles increased the free volume of membranes, resulting in the improvement of the CO2 permeability. The functionalized MWCNTs in situ inserted into ZIF-8 particles not only avoided the aggregation of ZIF-8 particles but also enhanced the CO2 adsorption property, resulting in the improvement of the CO2/N2 selectivity. Furthermore, the MWCNTs can provide rapid transport channels for CO2 molecules between two adjacent ZIF-8 particles and high mechanical properties for membranes. As a result, the MMMs with 8 wt% MWCNTs@ZIF-8 exhibited an excellent separation performance with CO2 permeability of 186.3 Barrer and CO2/N2 selectivity of 61.3, which surpassed the 2008 Robeson upper-bound. This study provided a new strategy for preparing high-performance CO2 separation membranes.