Zn Promoted Mg-Al Mixed Oxides-Supported Gold Nanoclusters for Direct Oxidative Esterification of Aldehyde to Ester
The synthesis of ester compounds is one of the most important chemical processes. In this work, Zn-Mg-Al mixed oxides with different Zn<sup>2+</sup>/Mg<sup>2+</sup> molar ratios were prepared via co-precipitation method and supported gold nanoclusters to study the direct oxid...
Main Authors: | , , , , |
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Format: | Article |
Language: | English |
Published: |
MDPI AG
2021-08-01
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Series: | International Journal of Molecular Sciences |
Subjects: | |
Online Access: | https://www.mdpi.com/1422-0067/22/16/8668 |
Summary: | The synthesis of ester compounds is one of the most important chemical processes. In this work, Zn-Mg-Al mixed oxides with different Zn<sup>2+</sup>/Mg<sup>2+</sup> molar ratios were prepared via co-precipitation method and supported gold nanoclusters to study the direct oxidative esterification of aldehyde and alcohol in the presence of molecular oxygen. Various characterization techniques such as N<sub>2</sub>-physical adsorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and CO<sub>2</sub> temperature programmed desorption (TPD) were utilized to analyze the structural and electronic properties. Based on the results, the presence of small amounts of Zn<sup>2+</sup> ions (~5 wt.%) provoked a remarkable modification of the binary Mg-Al system, which enhanced the interaction between gold with the support and reduced the particle size of gold. For oxidative esterification reaction, the Au<sub>25</sub>/Zn<sub>0.05</sub>MgAl-400 catalyst showed the best performance, with the highest turnover frequency (TOF) of 1933 h<sup>−1</sup>. The active center was believed to be located at the interface between metallic gold with the support, where basic sites contribute a lot to transformation of the substrate. |
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ISSN: | 1661-6596 1422-0067 |