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Role of Structural Defects in the Adsorption and Separation of C3 Hydrocarbons in Zr-Fumarate-MOF (MOF-801)

preprint
revised on 27.08.2019 and posted on 27.08.2019 by Paul Iacomi, Filip Formalik, Joao Marreiros, Jin Shang, Justyna Rogacka, Alexander Mohmeyer, Peter Behrens, Rob Ameloot, Bogdan Kuchta, Philip L. Llewellyn
An effective separation of propylene/propane mixtures is one of the most important processes in the petrochemical industry. Incidentally this separation is challenging due to the extensive similarities between both gases in terms of physicochemical properties such as, but not only limited to, boiling point, kinetic diameter and molecular weight. A drive to switch to less energy consuming processes, like adsorption or membrane separation, has highlighted several microporous metal organic frameworks as promising materials. In this work, we present a combined numerical and experimental investigation on propane and propylene adsorption in Zr-fumarate-MOF (also known as MOF-801), a small pore isoreticular analogue of UiO-66. Here, we demonstrate how the presence of structural defects can completely change the sorptive properties and separation performance of the Zr-fumarate-MOF, with enhanced capacity and gas diffusion rates for C3-sized hydrocarbons at the cost of kinetic selectivity. Extensive GCMC simulations performed on mixed defective supercells show that a percentage of missing cluster defects of around 1/8th can best account for the experimental results. Furthermore, analysis of low-frequency phonon spectra is used to explain gaseous diffusion in the original pristine material. A slight preference for propane over propylene is highlighted in the defective sample, and confirmed through column breakthrough experiments, suggesting the potential applicability of the Zr-fumarate-MOF in this challenging separation.

Funding

EU Horizon 2020 No. 641887 (project acronym: DEFNET)

Polish National Science Centre (NCN, grant no. 2015/17/B/ST8/00099)

Research Grants Council of Hong Kong (CityU 21301817)

History

Email Address of Submitting Author

paul.iacomi@umontpellier.fr

Institution

CNRS

Country

France

ORCID For Submitting Author

0000-0001-5477-1503

Declaration of Conflict of Interest

There are no conflicts on interest to declare.

Version Notes

- uploaded CIF structural files referenced in text - added ORCID for authors - more detailed referencing style - some minor rewording

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