Enhancing the separation performance of glassy PPO with the addition of a molecular sieve (ZIF-8): gas transport at various temperatures
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membranes-10-00056.pdf
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Author(s)
Benedetti, Francesco M.
De Angelis, Maria Grazia
Esposti, Micaela Degli
Fabbri, Paola
Masili, Alice
Orsini, Alessandro
Pettinau, Alberto
Date Issued
March 2020
Journal
Membranes
Publisher
Multidisciplinary Digital Publishing Institute
Citation
Benedetti, Francesco M., et al., "Enhancing the separation performance of glassy PPO with the addition of a molecular sieve (ZIF-8): gas transport at various temperatures." Membranes 10, 4 (Mar. 2020): no. 56 doi 10.3390/membranes10040056 ©2020 Author(s)
Version
Final published version
Abstract
In this study, we prepared and characterized composite films formed by amorphous poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and particles of the size-selective Zeolitic Imidazolate Framework 8 (ZIF-8). The aim was to increase the permselectivity properties of pure PPO using readily available materials to enable the possibility to scale-up the technology developed in this work. The preparation protocol established allowed robust membranes with filler loadings as high as 45 wt% to be obtained. The thermal, morphological, and structural properties of the membranes were analyzed via DSC, SEM, TGA, and densitometry. The gas permeability and diffusivity of He, CO[subscript 2], CH[subscript 4], and N[subscript 2] were measured at 35, 50, and 65°C. The inclusion of ZIF-8 led to a remarkable increase of the gas permeability for all gases, and to a significant decrease of the activation energy of diffusion and permeation. The permeability increased up to +800% at 45 wt% of filler, reaching values of 621 Barrer for He and 449 for CO[subscript 2] at 35°C. The ideal size selectivity of the PPO membrane also increased, albeit to a lower extent, and the maximum was reached at a filler loading of 35 wt% (1.5 for He/CO[subscript 2], 18 for CO[subscript 2]/N[subscript 2], 17 for CO[subscript 2]/CH[subscript 4], 27 for He/N[subscript 2], and 24 for He/CH[subscript 4].) The density of the composite materials followed an additive behavior based on the pure values of PPO and ZIF-8, which indicates good adhesion between the two phases. The permeability and He/CO[subscript 2] selectivity increased with temperature, which indicates that applications at higher temperatures than those inspected should be encouraged. ©2020 Keywords: gas separation; CO2 capture; mixed-matrix membranes
MIT Department
Massachusetts Institute of Technology. Department of Chemical Engineering
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DOI of Published Version
https://doi.org/10.3390/membranes10040056
