Palladium‐Percolated Networks Enabled by Low Loadings of Branched Nanorods for Enhanced H2 Separations

Nanoparticles (NPs) at high loadings are often used in mixed matrix membranes (MMMs) to improve gas separation properties, but they can lead to defects and poor processability that impede membrane fabrication. Herein, it is demonstrated that branched nanorods (NRs) with controlled aspect ratios can...

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Published in:Advanced materials (Weinheim) 2023-06, Vol.35 (26), p.e2301007-n/a
Main Authors: Hu, Leiqing, Chen, Kaiwen, Lee, Won‐Il, Kisslinger, Kim, Rumsey, Clayton, Fan, Shouhong, Bui, Vinh T., Esmaeili, Narjes, Tran, Thien, Ding, Yifu, Trebbin, Martin, Nam, Chang‐Yong, Swihart, Mark T., Lin, Haiqing
Format: Article
Language:English
Subjects:
Aspect ratio
carbon capture
Carbon dioxide
Chemical separation
Gas separation
H2 purification
MATERIALS SCIENCE
Membranes
mixed matrix materials
mixed matrix membranes
Nanoparticles
Nanorods
Nanowires
Palladium
Pd nanorods
percolated networks
Percolation
Polybenzimidazoles
Synthesis gas
Upper bounds
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Summary:Nanoparticles (NPs) at high loadings are often used in mixed matrix membranes (MMMs) to improve gas separation properties, but they can lead to defects and poor processability that impede membrane fabrication. Herein, it is demonstrated that branched nanorods (NRs) with controlled aspect ratios can significantly reduce the required loading to achieve superior gas separation properties while maintaining excellent processability, as demonstrated by the dispersion of palladium (Pd) NRs in polybenzimidazole for H2/CO2 separation. Increasing the aspect ratio from 1 for NPs to 40 for NRs decreases the percolation threshold volume fraction by a factor of 30, from 0.35 to 0.011. An MMM with percolated networks formed by Pd NRs at a volume fraction of 0.039 exhibits H2 permeability of 110 Barrer and H2/CO2 selectivity of 31 when challenged with simulated syngas at 200 °C, surpassing Robeson's upper bound. This work highlights the advantage of NRs over NPs and nanowires and shows that right‐sizing nanofillers in MMMs is critical to construct highly sieving pathways at minimal loadings. This work paves the way for this general feature to be applied across materials systems for a variety of chemical separations. Nanorods with suitable aspect ratios are ideal for constructing percolated networks in polymers with low loadings and easiness to fabricate defect‐free membranes, compared with nanoparticles and nanowires. This work demonstrates mixed matrix materials containing Pd‐percolated networks enabled by 3.9 vol% Pd branched nanorods, achieving H2/CO2 separation properties superior to state‐of‐the‐art membrane materials and surpassing the upper bound.
ISSN:0935-9648
1521-4095
DOI:10.1002/adma.202301007