Porous organosilicon nanotubes in pebax-based mixed-matrix membranes for biogas purification

Abstract For high-performance mixed-matrix membranes (MMMs), it is crucial to design gas transport channels in fillers to rationally manipulate the structure-property relationship. In this study, the novel porous organosilicon nanotubes (PSiNTs) were incorporated into Pebax to prepare MMMs for biogas purification (CO 2 /CH 4 separation). After comparing the separation performance of MMMs containing PSiNTs and MMMs containing non-porous organosilicon nanotubes (SiNTs)，it can be found that the porous structure on wall of organosilicon nanotubes had a significant effect on the improvement of the gas permeability. In addition, the amino-modified PSiNTs (N-PSiNTs) were prepared and introduced into membranes to significantly enhance the CO 2 permeability and CO 2 /CH 4 selectivity. Firstly, the porosity of N-PSiNTs afforded rapid gas transport channels in MMMs and intensified the diffusion mechanism, increasing the CO 2 permeability. Secondly, the reversible reaction between amino groups and CO 2 in MMMs intensified the facilitated transport mechanism, increasing the CO 2 /CH 4 selectivity. In particular, the Pebax-N-PSiNTs with 0.5 wt% and 1 wt% N-PSiNTs exhibited the optimal separation performance, which surpassed 2008 upper bound and were superior to the MMMs incorporated with other kinds of nanotubes.