CO₂gas separation using mixed matrix membranes based on polyethersulfone/MIL-100(Al)

The excessive use of natural gas and other fossil fuels by the industrial sector leads to the production of great quantities of gas pollutants, including CO2, SO2, and NOx. Consequently, these gases increase the temperature of the earth, producing global warming. Different strategies have been developed to help overcome this problem, including the utilization of separation membrane technology. Mixed matrix membranes (MMMs) are hybrid membranes that combine an organic polymer as a matrix and an inorganic compound as a filler. In this study, MMMs were prepared based on polyethersulfone (PES) and a type of metal-organic framework (MOF), Materials of Institute Lavoisier (MIL)-100(Al) [Al3O(H2O)2(OH)(BTC)2] (BTC: benzene 1,3,5-tricarboxylate) using a phase inversion method. The influence on the properties of the produced membranes by addition of 5, 10, 20, and 30% MIL-100(Al) (w/w) to the PES was also investigated. Fourier-transform infrared spectroscopy (FTIR) analysis indicated that no chemical interactions occurred between PES and MIL-100(Al). Scanning electron microscope (SEM) images showed agglomeration at PES/MIL-100(Al) 30% (w/w) and that the thickness of the dense layer increased up to 3.70 μm. After the addition of MIL-100(Al) of 30% (w/w), the permeability of the MMMs for CO2, O2, and N2 gases was enhanced by approximately 16, 26, and 14 times, respectively, as compared with a neat PES membrane. The addition of MIL-100(Al) to PES increased the thermal stability of the membranes, reaching 40°C as indicated by thermogravimetry analysis (TGA). An addition of 20% MIL-100(Al) (w/w) increased membrane selectivity for CO2/O2 from 2.67 to 4.49 (approximately 68.5%), and the addition of 10% MIL-100(Al) increased membrane selectivity for CO2/N2 from 1.01 to 2.12 (approximately 110.1%).