Defect-Engineered Metal-Organic Framework/Polyimide Mixed Matrix Membrane for CO2 Separation.

A novel defect-engineered MOF (quasi ZrFum or Q-ZrFum) was synthesized via a controlled thermal deligandation process and incorporated into a CO2-philic 6FDA-durene polyimide (PI) matrix to form Q-ZrFum loaded MMMs. Defect-engineered MOFs and fabricated MMMs were investigated in terms of their characteristic properties and separation performance. The incorporation of defects into the MOF structure increases the pore size and provides unsaturated active metal sites that positively affect CO2 molecule transport. After the deligandation process, the interfacial compatibility between the Q-ZrFum particles and the PI matrix increases, which improves the mechanical strength of Q-ZrFum loaded membranes. MMM containing 5 wt.% of defect-engineered Q-ZrFum exhibits excellent CO2 permeability of 1308 Barrer which increased by 99% compared to the pure PI membrane (656 Barrer) at a feed pressure of 2 bar. Moreover, CO2/CH4 and CO2/N2 selectivity reached 44 and 26.6 which increased by about 70 and 16%, respectively. This study emphasizes that defect-engineered MOFs can be promising candidates for use as filler in the preparation of MMMs for the future development of membrane-based gas separation applications.