High solvent resistance PTFPMS/PEI hollow fiber composite membrane for gas separation

Abstract

Poly(fluoropropylmethylsiloxane) (PTFPMS), which had different properties with polydimethylsiloxane (PDMS) due to C-F bond. The limitation for PTFPMS membrane to achieve industrial-scale applications was the forms of membrane modules. Thus, PTSPMS/polyetherimide (PEI) hollow fiber composite membranes have been prepared. Effects of PTFPMS concentration, coating method, selective layer thickness, operating pressure and temperature on the separation performance of the composite membranes have been investigated. PTFPMS can form a top dense layer on PEI substrate under a suitable concentration. The gas permeation rates decrease in the following order: CO 2 > C 3 H 6 > H 2 > O 2 > CH 4 > N 2 . Permeation rates of CO 2 and C 3 H 6 change significantly with the increase of operating pressure. Based on pure gas permeation rates, the selectivities range from 16.03 to 18.80 for CO 2 /N 2 and 11.75-19.76 for C 3 H 6 /N 2 under operating pressure ranging from 0.1 to 0.5 MPa. Operating temperature has significant impact on permeation rates of CO 2 , CH 4 , O 2 , H 2 and N 2 . PTFPMS/PEI hollow fiber composite membrane exhibits stable separation performance after immersed in i-octane and petroleum ether. The selectivity decreases ratio of PTFPMS/PEI hollow fiber composite membranes varies in the range of 1.56-10.70%, much lower than those of PDMS/PEI membranes of 8.02-21.34%.