Farzaneh, Amirfarrokh, Zhou, Ming, Antzutkin, Oleg N., Bacsik, Zoltán, Hedlund, Jonas, Holmgren, Allan and Grahn, Mattias (2016) Adsorption of butanol and water vapors in silicalite-1 films with a low defect density. Langmuir, 32 (45). pp. 11789-11798. doi:10.1021/acs.langmuir.6b03326 ISSN 0743-7463.
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Abstract
Pure silica zeolites are potentially hydrophobic and have therefore been considered to be interesting candidates for separating alcohols, e.g., 1-butanol, from water. Zeolites are traditionally synthesized at high pH, leading to the formation of intracrystalline defects in the form of silanol defects in the framework. These silanol groups introduce polar adsorption sites into the framework, potentially reducing the adsorption selectivity toward alcohols in alcohol/water mixtures. In contrast, zeolites prepared at neutral pH using the fluoride route contain significantly fewer defects. Such crystals should show a much higher butanol/water selectivity than crystals prepared in traditional hydroxide (OH–) media. Moreover, silanol groups are present at the external surface of the zeolite crystals; therefore, minimizing the external surface of the studied adsorbent is important. In this work, we determine adsorption isotherms of 1-butanol and water in silicalite-1 films prepared in a fluoride (F–) medium using in situ attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy. This film was composed of well intergrown, plate-shaped b-oriented crystals, resulting in a low external area. Single-component adsorption isotherms of 1-butanol and water were determined in the temperature range of 35–80 °C. The 1-butanol isotherms were typical for an adsorbate showing a high affinity for a microporous material and a large increase in the amount adsorbed at low partial pressures of 1-butanol. The Langmuir–Freundlich model was successfully fitted to the 1-butanol isotherms, and the heat of adsorption was determined. Water showed a very low affinity for the adsorbent, and the amounts adsorbed were very similar to previous reports for large silicalite-1 crystals prepared in a fluoride medium. The sample also adsorbed much less water than did a reference silicalite-1(OH–) film containing a high density of internal defects.The results show that silicalite-1 films prepared in a F– medium with a low density of defects and external area are very promising for the selective recovery of 1-butanol from aqueous solutions.
| Item Type: | Journal Article |
|---|---|
| Subjects: | Q Science > QD Chemistry |
| Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics |
| Library of Congress Subject Headings (LCSH): | Butanol , Water, Adsorption, Zeolites |
| Journal or Publication Title: | Langmuir |
| Publisher: | American Chemical Society |
| ISSN: | 0743-7463 |
| Official Date: | 15 November 2016 |
| Dates: | Date Event 15 November 2016 Published 24 October 2016 Available 9 September 2016 Submitted |
| Volume: | 32 |
| Number: | 45 |
| Page Range: | pp. 11789-11798 |
| DOI: | 10.1021/acs.langmuir.6b03326 |
| Status: | Peer Reviewed |
| Publication Status: | Published |
| Access rights to Published version: | Open Access (Creative Commons open licence) |
| Date of first compliant deposit: | 28 February 2017 |
| Date of first compliant Open Access: | 28 February 2017 |
| Funder: | Sweden. Vetenskapsrådet [Research Council], Kempestiftelserna [The Kempe Foundations] |
| Grant number: | Grant 621-2011-4060 (Sweden. Vetenskapsrådet [Research Council]), |
| URI: | https://wrap.warwick.ac.uk/84125/ |
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