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Open AccessFeature PaperArticle

Enhancing the Separation Performance of Glassy PPO with the Addition of a Molecular Sieve (ZIF-8): Gas Transport at Various Temperatures

Department of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, 40131 Bologna, Italy
Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Sotacarbo S.p.A., Grande Miniera di Serbariu, 09013 Carbonia, Italy
Authors to whom correspondence should be addressed.
Membranes 2020, 10(4), 56;
Received: 9 March 2020 / Revised: 21 March 2020 / Accepted: 24 March 2020 / Published: 27 March 2020
(This article belongs to the Special Issue Polymer Membranes for Gas Separation)
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, CO2, CH4, and N2 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 CO2 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/CO2, 18 for CO2/N2, 17 for CO2/CH4, 27 for He/N2, and 24 for He/CH4). 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/CO2 selectivity increased with temperature, which indicates that applications at higher temperatures than those inspected should be encouraged. View Full-Text
Keywords: gas separation; CO2 capture; mixed-matrix membranes gas separation; CO2 capture; mixed-matrix membranes
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MDPI and ACS Style

Benedetti, F.M.; De Angelis, M.G.; Degli Esposti, M.; Fabbri, P.; Masili, A.; Orsini, A.; Pettinau, A. Enhancing the Separation Performance of Glassy PPO with the Addition of a Molecular Sieve (ZIF-8): Gas Transport at Various Temperatures. Membranes 2020, 10, 56.

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