Enhanced gas separation by multi-walled carbon nanotubes MOF glass membranes

Abstract

Carbon nanotubes (CNTs), known for their elevated specific surface area, exemplary mechanical properties and thermal stability, are regarded as optimal reinforcing fillers for the fabrication of mixed matrix membranes (MMMs). In this study, self-supported MMMs were prepared using melted zeolitic imidazolate framework (ZIF), denoted ZIF-62 glass, as the continuous phase and multi-walled CNTs (MWCNTs) particles as the dispersed phase. The resulting membranes were thoroughly characterized, and the effect of different incorporation amounts of MWCNTs on the gas separation performance was investigated. It is noteworthy that at an incorporation amount of 4 wt. % MWCNTs, the ideal selectivity of prepared self-supported (a_gZIF-62)_0.96(MWCNTs)_0.04 MMM for CO₂/N₂ and CH₄/N₂ was 31.2 and 8.6 respectively, exceeding the 2019 Robeson upper bound. The results demonstrated that MWCNTs have excellent gas transport properties and significantly enhance the separation performance. Furthermore, the self-supported (a_gZIF-62)_0.96(MWCNTs)_0.04 MMM also exhibited excellent mechanical properties and pressure resistance, making them highly promising candidates for advanced gas separation applications. This study not only highlights the effectiveness of MWCNTs as functional fillers in MMMs but also presents a novel approach for designing high-performance gas separation membranes.