Optimization of Fabrication Parameters of Polymer-Inorganic Mixed Matrix Membranes using Zeolitic Imidazolate Framework Nanofiller and 6FDA-Durene Polyimide.

The presence of carbon dioxide in natural gas has greatly reduced the heating value of the gas and caused corrosion to the transport pipelines. Membrane technology is well-known in the oil and gas industry especially in the separation of carbon dioxide from natural gas due to its cheaper capital cost, smaller size and the ability to separate mixture of more than 20% carbon dioxide in it. Although mixed matrix membranes have been widely reported as a potential membrane material in separation of carbon dioxide from natural gas, there are still problems and challenges in the fabrication of defects free and particles-agglomeration free mixed matrix membrane. Therefore, in the present research, the parameters including the sonication and stirring duration in the fabrication of zeolitic imidazolate framework (ZIF-8) nanofiller and 6FDA-durene polyimide mixed matrix membrane was studied and optimized. The resultant mixed matrix membranes were characterized by using field emission scanning electron microscopy (FESEM), scanning electron microscopy (SEM) and also energy dispersive x-ray spectroscopy (EDX) in order to investigate its morphology and the agglomeration of the dispersed ZIF-8. It was shown in FESEM and SEM that ZIF-8 nanofiller is compatible with 6FDA-durene polymeric matrix. Thermogravimetric analysis (TGA) results showed that the MMM are stable up to 400 °C while differential scanning calorimetry (DSC) showed that the glass transition temperature, Tg of the resultant mixed matrix membrane is 15 °C higher than the pristine membrane. Lastly, permeation testing was carried out at 3.5 bar in order to test the performance of the resultant membrane in CO2/CH4 separation. Generally, the incorporation of ZIF-8 nanofillers in 6FDA-durene polymer membrane results in the increase in CO2 and CH4 permeability while a drop of CO2/CH4 selectivity is observed. MMM with the total stirring and sonication duration of 11 hours displayed the best separation performance as well as the most well dispersed ZIF-8 among the 7 sets of mixed matrix membrane fabricated.