Synthesis and performance analysis of a polysulfone braid-supported hollow fiber membrane for natural gas purification

Abstract

To address the issue of low mechanical strength in self-supported hollow fiber membranes, a research study was conducted to fabricate polysulfone braid-reinforced hollow fiber (PSF BRHF) membranes for natural gas purification. In this study, polyethylene (PET) was used as a braid support. PSF BRHF membranes were fabricated by employing dip coating and drying technique. The BRHF membranes underwent comprehensive analysis, including the manipulation of polymer (PSF) concentration (15 wt%, 18 wt%, and 21 wt%) and the number of coating layers (1–4). Characterization of the fabricated membrane samples involved scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), gas separation performance testing, and mechanical strength testing. The results indicated that membranes fabricated with higher polymer concentrations exhibited a denser structure with a thicker separation layer. An increase in the separation layer thickness was also observed with an increasing number of coating layers. Importantly, all fabricated membrane samples demonstrated remarkable thermal stability. To assess the performance, gas separation tests were conducted using pure gases at 3 bar. Notably, the membrane sample with 21 wt% PSF and the 3rd coating layer (21_3 PSF) exhibited the most promising gas separation performance among all the samples selected to carry out the separation performance test, achieving a CO2/CH4 selectivity of 1.83. Mechanical strength testing revealed that 21_3 PSF BRHF (68.2 MPa) fabricated in this study outperformed conventional self-supported PSF hollow fiber membranes (9.44 MPa), as reported in the literature. These findings underscore the potential of BRHF membranes for natural gas purification, although further improvements are still possible.