Enhanced CO2/CH4 separation using amine-modified ZIF-8 mixed matrix membranes

Amine-modified mixed matrix membranes (A-Ms) have been developed with improved anti-plasticization behavior at high pressure for natural gas purification. Neat polysulfone (PSf) hollow fiber membranes and amine-modified zeolitic imidazole framework-8 (A-ZIF-8) blended PSf membranes have been prepared with the aim of purifying natural gas. The fabricated membranes have been evaluated using gas performance tests, thermogravimetric analysis (TGA), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and field emission scanning electron microscopy (FESEM). When tested using pure gases, the membrane with 0.25 wt percent A-ZIF-8 demonstrated a substantial enhancement in CO2/CH4 selectivity of 50 %, 72 %, and 69 % when compared to the neat membrane, and an increase of 33 %, 78 %, and 77 % in CO2/CH4 selectivity compared to the virgin ZIF-8-based membrane at feed pressures of 6, 8, and 10 bar (g), respectively. Subsequently, the separation performance has decreased due to the increased A-ZIF-8 loading. Improved anti-plasticization behavior at high feed pressure is further demonstrated by the exceptional gas separation performance at low loading of A-ZIF-8 nanoparticles. The promising results showed the potential use of A-ZIF-8 for natural gas purification.