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Language: English

Conflict of Interest: In relation to this article, we declare that there is no conflict of interest.

Publication history: Received January 8, 2019
Accepted April 8, 2019

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/bync/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Characteristics of exfoliated HNb3O8 nanosheet derived from amorphous niobic acid and its application to dehydration of 2-heptanol

Jongha Park¹ Young-Woong Suh^{1 2†}

¹Department of Chemical Engineering, Hanyang University, Seoul 04763, Korea ²Research Institute of Industrial Science, Hanyang University, Seoul 04763, Korea

Korean Journal of Chemical Engineering, June 2019, 36(6), 843-850(8), 10.1007/s11814-019-0269-z

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Abstract

The synthesis of exfoliated HNb3O8 nanosheet (eHNb3O8) generally starts from the mixing of K2CO3 with crystalline Nb2O5 and involves a very routine procedure in subsequent multi-steps. Herein, we report for the first time the use of niobic acid (NBA, Nb2O5·nH2O) as Nb source for the preparation of final eHNb3O8. Different from the analogue derived from crystalline Nb2O5, the prepared nanosheet contains a very small amount of potassium ion and exhibits high stability in consecutive runs for the dehydration reaction. The linkage between these two features is confirmed by the inferior stability of potassium-deficient eHNb3O8 samples prepared via prolonged proton-exchange. When a series of niobate materials are examined, the remarkable finding is the higher K/Nb ratio in NBA-derived KNb3O8 than the theoretical value. This is attributed to the acidity of amorphous NBA by which the carbonate ion of K2CO3 is decomposed into CO2 in the preparation of the solid mixture K2CO3-NBA. These more intercalated K+ cannot be all displaced with proton by the general ion-exchange process employed for Nb2O5-derived eHNb3O8. Consequently, the proposed model suggests that the potassium ion remaining in NBA-derived eHNb3O8 acts as a ligating element to tie up a single, exfoliated nanosheet into several.

Keywords

Exfoliated HNb3O8 Nanosheet Amorphous Niobic Acid Potassium Ion

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