2016年6月
Surface and interlayer base-characters in lepidocrocite titanate: The adsorption and intercalation of fatty acid
JOURNAL OF SOLID STATE CHEMISTRY
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- 巻
- 238
- 号
- 開始ページ
- 175
- 終了ページ
- 181
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1016/j.jssc.2016.03.030
- 出版者・発行元
- ACADEMIC PRESS INC ELSEVIER SCIENCE
While layered double hydroxides (LDHs) with positively-charged sheets are well known as basic materials, layered metal oxides having negatively-charged sheets are not generally recognized so. In this article, the surface and interlayer base-characters of O2- sites in layered metal oxides have been demonstrated, taking lepidocrocite titanate K0.8Zn0.4Ti1.6O4 as an example. The low basicity (0.04 mmol CO2/g) and low desorption temperature (50-300 degrees C) shown by CO2- TPD suggests that O2- sites at the external surfaces is weakly basic, while those at the interlayer space are mostly inaccessible to CO2. The liquid-phase adsorption study, however, revealed the uptake as much as 37% by mass of the bulky palmitic acid (C-16 acid). The accompanying expansion of the interlayer space by similar to 0.1 nm was detected by PXRD and TEM. In an opposite manner to the external surfaces, the interlayer O2- sites can deprotonate palmitic acid, forming the salt (i.e., potassium palmitate) occluded between the sheets. Two types of basic sites are proposed based on ultrafast H-1 MAS NMR and FTIR results. The interlayer basic sites in lepidocrocite titanate leads to an application of this material as a selective and stable two-dimensional (2D) basic catalyst, as demonstrated by the ketonization of palmitic acid into palmitone (C-31 ketone). Tuning of the catalytic activity by varying the type of metal (Zn, Mg, and Li) substituting at Ti-IV sites was also illustrated. (C) 2016 Elsevier Inc. All rights reserved.
- リンク情報
- ID情報
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- DOI : 10.1016/j.jssc.2016.03.030
- ISSN : 0022-4596
- eISSN : 1095-726X
- Web of Science ID : WOS:000375635200024