Molecular sieving of linear and branched C6 alkanes by tannin-derived carbons

• Published in: Carbon (New York) Vol. 174; pp. 413 - 422
• Main Authors: Castro-Gutiérrez, Jimena, De Oliveira Jardim, Erika, Canevesi, Rafael L.S., Silvestre-Albero, Joaquin, Kriesten, Martin, Thommes, Matthias, Celzard, Alain, Fierro, Vanessa
• Format: Journal Article
• Language: English
• Published: New York Elsevier Ltd 15.04.2021; Elsevier BV; Elsevier
• Subjects: Adsorption; Alkane separation; Alkanes; Carbon; Chemical and Process Engineering; Chemical Sciences; Engineering Sciences; Hexanes; Inorganic chemistry; Isomers; Low cost; Material chemistry; Metal matrix composites; Micro-mesoporous carbons; Molecular sieves; Nanotubes; Pore size; Porous materials; Selectivity; Separation; Tannins; Alkane separation; Micro-mesoporous carbons; Tannins; Molecular sieves; molecular sieves; micro-mesoporous carbons; tannins; alkane separation
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2020.12.061

Two micro-mesoporous carbons (MMCs): a disordered mesoporous carbon (DMC) and an ordered mesoporous carbon (OMC), synthesized by an easy, low-cost, and green method are proposed as efficient hydrocarbon sieves for the separation of C6 isomers: n-hexane (nHEX), 2-methylpenthane (2 MP) and 2,2-dimethylbutane (22DMB). Their textural characterization reveals a highly interconnected pore network within the DMC, while a reverse hierarchy of ordered mesopores only accessible through narrow micropores is found in the OMC. The pore texture strongly affects their adsorption performance by kinetic and molecular sieving effects; the narrow constrictions in the OMC allow adsorption of nHEX and partially 2 MP but not 22DMB, whereas the highly connected pore network of DMC allows adsorption of the three isomers. Multi-component adsorption isotherms calculated from the single-component experimental results by ideal adsorbed solution theory (IAST) demonstrates that the OMC material has a remarkably high selectivity for the adsorption of nHEX and nHEX + 2 MP from binary and ternary mixtures, respectively. To the best of the authors’ knowledge, such behavior has never been reported so far for carbon materials. Hence, this study shows that tannin-derived MMCs have great potential to be used as an eco-friendly and low-cost alternative for the selective separation of di-branched C6 isomers. [Display omitted] •Mesoporous ordered and disordered carbons, OMC and DMC, were prepared from tannin•A reverse hierarchical mesoporous structure is identified in the OMC•Branched C6, 2 MP and 22DMB, are partially adsorbed or excluded from the OMC•The IAST separation selectivity of nHEX/22DMB is higher than 1012•OMC outperforms well-known MOFs in nHEX separation selectivity