Pim-1-Based Membranes Mediated with Co2-Philic Mxene Nanosheets for Superior Co2/N2 Separation

Abstract

Membrane gas separation technologies have emerged as highly prospective avenues for the selective separation of CO2. In this research, a novel array of mixed matrix membranes (MMMs) was engineered, integrating two-dimensional nanosheets of MXene, specifically Ti₃C₂Tₓ, into polymers of intrinsic microporosity (PIMs) to selectively separate CO₂ from N₂. The inclusion of Ti₃C₂Tₓ nanosheets, rich in polar functional groups, significantly increases the affinity between CO₂ molecules and the fabricated MMMs. Additionally, the precise modulation of the molecular diffusion channels for CO₂ and N₂ is achievable due to the interlayer spacing between MXene layers (~0.35nm) within the PIM-1 matrix. This innovation is predicated on the synergistic effect of solution-diffusion and molecular sieving mechanisms that underpin the gas separation process, leading to a marked improvement in both selectivity for CO₂ over N₂ and the permeability of CO₂. Among the series, the MMM with a 0.5 wt% MXene displayed exceptional separation efficiency, achieving a CO₂ permeability of 12475.3 Barrer and a CO₂/N₂ selectivity of 32.7. Notably, each PIM-1/MXene membrane composition examined in this study exceeded the Robeson upper bound set in 2019, indicating their substantial promise for CO₂ separation and capture in industrial applications.

Keywords: Mixed matrix membranes, PIM-1, MXene, CO2/N2 separation, CO2 permeability