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

Abstract

AbstractIn 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 NH2 on the characteristics of the generated TFN membranes and their gas transport properties, including TGA, FESEM, BET, gas adsorption tests, and a series of CO2/CH4 mixed gas separation tests. According to the FESEM pictures, the NH2‐MIL 53(Al) particles were well distributed in the TFN membranes, with no apparent agglomeration, The gas adsorption experiment of NH2‐MIL 53(Al) particles showed that they adsorb CO2 selectively. The incorporation of NH2‐MIL 53(Al) into TFN membranes led to improved CO2/CH4 selectivity and increased gas permeability. In addition, CO2/CH4 selectivity and CO2 permeability of the CO2/CH4 mixed gas were enhanced from 11.05 to 26.55 and from 111.6 to 260.2 Barrer, respectively, when NH2‐MIL 53(Al) 20 wt% was added to the TFN membrane. In the CO2/CH4 mixed gas experiment, increasing the temperature from 30 to 50°C increased the permeability of both CH4 and CO2 while decreasing the CO2/CH4 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 CO2/CH4 separation improved. Also, with pure gas, the increase in NH2‐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 NH2‐MIL53(Al).