High–Selective Separation Performance of CO2 from CH4 by Interfacial Engineering of Ultra-low-dose Bimetallic Pyrazine-MOF based Mixed Matrix Membranes

The CO2 capturing is much more important not only in fuel upgrading but also for controlling global warming issues. Although much Metal-Organic Framework (MOF) based mixed matrix membranes (MMMs) exhibited great potential, the interfacial fine-tuning of inorganic MOF and organic membrane matrix was still a big obstacle. Herein, a novel bimetallic Pyrazine-functionalized MOF based polysulfone (PSf) mixed matrix membrane was prepared with adaptive interfaces via the interfacial plasticizer polyethylene glycol (PEG). The filler MOF greatly enhanced the CO2 capturing ability of pure PSf and PSf/PEG blend membranes. Structural characterizations revealed defect-free membranes. The mechanical test implied that by adding MOF in PSf, brittleness appeared and strength decreased from 2.84 to 2.26 MPa, but this strength increased up to 4.11 MPa by adding PEG. The interfacial-controlled PSf/PEG/Pyrazine-MOF membranes showed the highest CO2 permeability and solubility without loss of selectivity compared to regular MOF blended MMMs or PSf/PEG blend membranes. The permeability of CO2 significantly increased from 6.82 Barrer (for pure PSf membrane) to 17.13 Barrer (for PSf/PEG/Pyrazine-MOF membrane only adding 0.2% ultra-low-dose Pyrazine-MOF with 2% PEG). The study revealed a robust and efficient strategy to elevate gas separation performances of MMMs via the interfacial engineering.