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/CH 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 permeability and CO/CH selectivity. Firstly, the porosity of N-PSiNTs afforded rapid gas transport channels in MMMs and intensified the diffusion mechanism, increasing the CO permeability. Secondly, the reversible reaction between amino groups and CO in MMMs intensified the facilitated transport mechanism, increasing the CO/CH 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.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The authors gratefully acknowledge the financial support from the National Key R&D Program of China (No. 2017YFB0603400), National Natural Science Foundation of China (Nos. 21838008 and 21621004), State Key Laboratory of Organic-Inorganic Composites (oic-201701004), State Key Laboratory of Petroleum Pollution Control (No. PPC2017014), State Key Laboratory of Separation Membranes and Membrane Processes and Tianjin Polytechnic University (No. M1–201701), National Key Laboratory of United Laboratory for Chemical Engineering (SKL-ChE-17B01).