Ethene/ethane separation by the MOF membrane ZIF-8: Molecular correlation of permeation, adsorption, diffusion

• Published in: Journal of membrane science Vol. 369; no. 1; pp. 284 - 289
• Main Authors: Bux, Helge, Chmelik, Christian, Krishna, Rajamani, Caro, Juergen
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.03.2011; Elsevier
• Subjects: adsorption; ambient temperature; artificial membranes; Chemistry; Colloidal state and disperse state; ethane; Ethene/ethane separation; ethylene; Exact sciences and technology; GCMC simulations; General and physical chemistry; IR microscopy; Membranes; microscopy; MOF membrane; Monte Carlo method; Surface physical chemistry; ZIF-8 membrane; Ethene/ethane separation; ZIF-8 membrane; IR microscopy; MOF membrane; GCMC simulations; Monte Carlo method; Correlation; Separation; Ethylene; Permeation; Selectivity; Ethane; Single crystal; Sorption; Adsorption; Simulation; Membrane; Diffusion; Room temperature
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2010.12.001

[Display omitted] ▶ ZIF-8 membrane can separate ethene/ethane mixtures with selectivities between 2 and 3. ▶ From mixture adsorption and diffusion data, the membrane selectivity can be predicted. ▶ Both IR microscopy and grand canonical Monte Carlo simulation can give the mixture data. The newly developed MOF membrane ZIF-8 separates an equimolar ethene/ethane mixture at room temperature for 1 and 6 bar feed pressure, respectively, with a selectivity of 2.8 and 2.4. Independent sorption uptake studies of an ethene/ethane mixture on a big ZIF-8 single crystal by IR microscopy detection show in combination with grand canonical Monte Carlo simulations that this moderate ethene selectivity of the ZIF-8 membrane can be explained by the interplay of a preferential ethane adsorption selectivity competing with a preferential ethene diffusion selectivity. This means, that ethane adsorbs stronger than ethene, but ethene diffuses faster and overcompensates the adsorption preference of ethane, resulting in a membrane permeation selectivity for ethene.