Gas-sieving zeolitic membranes fabricated by condensation of precursor nanosheets

Abstract
The synthesis of molecular-sieving zeolitic membranes by the assembly of building blocks, avoiding the hydrothermal treatment, is highly desired to improve reproducibility and scalability. Here we report exfoliation of the sodalite precursor RUB-15 into crystalline 0.8-nm-thick nanosheets, that host hydrogen-sieving six-membered rings (6-MRs) of SiO4 tetrahedra. Thin films, fabricated by the filtration of a suspension of exfoliated nanosheets, possess two transport pathways: 6-MR apertures and intersheet gaps. The latter were found to dominate the gas transport and yielded a molecular cutoff of 3.6 Å with a H2/N2 selectivity above 20. The gaps were successfully removed by the condensation of the terminal silanol groups of RUB-15 to yield H2/CO2 selectivities up to 100. The high selectivity was exclusively from the transport across 6-MR, which was confirmed by a good agreement between the experimentally determined apparent activation energy of H2 and that computed by ab initio calculations. The scalable fabrication and the attractive sieving performance at 250–300 °C make these membranes promising for precombustion carbon capture.

Citation
Dakhchoune, M., Villalobos, L. F., Semino, R., Liu, L., Rezaei, M., Schouwink, P., … Agrawal, K. V. (2020). Gas-sieving zeolitic membranes fabricated by condensation of precursor nanosheets. Nature Materials. doi:10.1038/s41563-020-00822-2

Acknowledgements
We thank our host institution, EPFL, for generous support. This work was primarily funded by the Swiss Competence Center for Energy Research: Efficiency of Industrial Processes (SCCER-EIP). A part of this work was funded by the Swiss National Science Foundation (Assistant Professor Energy Grant, grant no. PYAPP2-173645). The computational aspects of this work were supported by a grant from the Swiss National Supercomputing Centre (CSCS) under project ID s887. We acknowledge E. Oveisi for the helpful discussions on electron microscopy.

Publisher
Springer Nature

Journal
Nature Materials

DOI
10.1038/s41563-020-00822-2

Additional Links
http://www.nature.com/articles/s41563-020-00822-2

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