Alkali-Free Hydrothermally Reconstructed NiAl Layered Double Hydroxides for Catalytic Transesterification

Abstract

NiAl layered double hydroxides (LDHs) are promising bifunctional catalysts comprising tunable redox and Lewis acidic sites. However, most studies of NiAl LDH employ alkali hydroxide carbonate precipitants which may contaminate the final LDH catalyst and leach into reaction media. Here, we report an alkali-free route to prepare NixAl LDHs with a composition range x = 1.7 to 4.1 using (NH4)2CO3 and NH4OH as precipitants. Activation of LDHs by calcination−rehydration protocols reveal NixAl LDHs can be reconstructed under mild hydrothermal treatment (110 °C for 12 h), with the degree of reconstruction increasing with Ni content. Catalyst activity for tributyrin transesterification with methanol was found to increase with Ni content and corresponding base site loadings; TOFs also increased, suggesting that base sites in the reconstructed LDH are more effective for transesterification. Hydrothermally reconstructed Ni4.1Al LDH was active for the transesterification of C4−C12 triglycerides with methanol and was stable towards leaching during transesterification.

Publication DOI: https://doi.org/10.3390/catal12030286
Divisions: College of Engineering & Physical Sciences > Energy and Bioproducts Research Institute (EBRI)
Additional Information: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).
Uncontrolled Keywords: biodiesel,layered double hydroxides,transesterification,hydrothermal,nickel,aluminum,solid base
Publication ISSN: 2073-4344
Full Text Link:
Related URLs: https://www.mdp ... 3-4344/12/3/286 (Publisher URL)
PURE Output Type: Article
Published Date: 2022-03-03
Accepted Date: 2022-02-20
Authors: Tajuddin, Nazrizawati A.
Manayil, Jinesh C. (ORCID Profile 0000-0002-9864-3332)
Lee, Adam F.
Wilson, Karen

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