Performance of amine‐functionalized MIL‐53 incorporated thin‐film nanocomposite Pebax membranes for CO2/CH4 mixed gas separation

Abstract In the present paper, the gas transport characteristics of amine‐functionalized MIL‐53 metal–organic frameworks (MOFs) integrated thin‐film nanocomposite (TFN) Pebax 2533 membranes dip‐coated over a polysulfone (PSF) layer were studied. Various characterization methods were used to investigate the impact of ligand functionalization by NH 2 on the characteristics of the generated TFN membranes and their gas transport properties, including TGA, FESEM, BET, gas adsorption tests, and a series of CO 2 /CH 4 mixed gas separation tests. According to the FESEM pictures, the NH 2 ‐MIL 53(Al) particles were well distributed in the TFN membranes, with no apparent agglomeration, The gas adsorption experiment of NH 2 ‐MIL 53(Al) particles showed that they adsorb CO 2 selectively. The incorporation of NH 2 ‐MIL 53(Al) into TFN membranes led to improved CO 2 /CH 4 selectivity and increased gas permeability. In addition, CO 2 /CH 4 selectivity and CO 2 permeability of the CO 2 /CH 4 mixed gas were enhanced from 11.05 to 26.55 and from 111.6 to 260.2 Barrer, respectively, when NH 2 ‐MIL 53(Al) 20 wt% was added to the TFN membrane. In the CO 2 /CH 4 mixed gas experiment, increasing the temperature from 30 to 50°C increased the permeability of both CH 4 and CO 2 while decreasing the CO 2 /CH 4 selectivity. Furthermore, the performance of the prepared membranes was assessed at different feed pressures ranging from 4 to 8 bar. As the feed pressure increased, the CO 2 /CH 4 separation improved. Also, with pure gas, the increase in NH 2 ‐MIL53(Al) loading resulted in lower diffusivity selectivity amounts for the TFN membrane than for the pristine TFN, and solubility selectivity was enhanced from 5 to 20 wt% and was reduced to 25 and 30 wt% in the TFN, respectively. In the present study, the best results were obtained at 6 bar pressure, 30°C temperature, and 20 wt% loading of NH 2 ‐MIL53(Al).