Pebax and CMC@MXene-Based Mixed Matrix Membrane with High Mechanical Strength for the Highly Efficient Capture of CO2

Abstract

Sustainable and energy-efficient molecular separation requires membranes with high permeability and selectivity. Among various membranes, the mixed matrix membranes (MMMs) prepared from two-dimensional MXene materials with well-defined nanochannels are expected to be used for the precise separation of molecules. However, the stacking of a large number of 2D MXene nanosheets creates gas mass transfer barriers, resulting in a significant reduction in gas permeability. To solve this issue, herein, a high-performance self-supporting Pebax/CMC@MXene MMM was prepared by a combination of 2D MXene nanosheets with branched carboxymethyl cellulose (CMC) for CO2 gas separation from natural gas and flue gas. Gas separation experimental results show that the as-prepared self-supporting Pebax/CMC@MXene MMMs can significantly improve gas permeance and selectivity. When the loading of MXene nanosheets in the CMC@MXene filler was fixed at 1.5 mg/mL, the CO2 permeance of Pebax/CMC@MXene MMMs was found to be 521 GPU, and the CO2/N2 selectivity was calculated to be 40.1. Meanwhile, the CO2 permeance was measured to be 444 GPU, and the CO2/CH4 selectivity was calculated to be 40.4. In addition, the resulted as-prepared self-supporting Pebax/CMC@MXene MMM possesses excellent thermal stability and long-term durability; after a 60 h test, its separation performance has no obvious change. The work provides a novel strategy to construct MMMs with less mass transfer barrier for highly efficient capture of CO2 from natural gas and flue gas.