Selective oxidation of cyclohexane: Ce promotion of nanostructured manganese tungstate
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Accepted version
Author(s)
Graça, I
Al-Shihri, S
Chadwick, D
Type
Journal Article
Abstract
Cyclohexane selective oxidation over nanostructured MnWO4promoted with increasing amounts of Ce (1–5 wt%) has been investigated at mild conditions using molecular oxygen as oxidant. MnWO4nanorods were found to be an active catalyst for cyclohexane selective oxidation with selectivity to KA oil (cyclohexanol + cyclohexanone) of approximately 85%. The catalytic performance was improved by impregnation with 1 wt% Ce while the textural properties and crystallinity were preserved and Ce was well-dispersed on the surface. XPS analysis of 1%Ce-MnWO4showed Ce to be present mainly as Ce3+, which is known to promote oxygen adsorption, activation, and mobility. At higher Ce content, the proportion of Ce4+increased to be the main Ce species and large, heterogeneously-dispersed Ce oxide particles are formed on the catalyst surface. The lower Ce3+content reduces the promoting effect while the large Ce oxide particles block access to the active sites on the surface of the MnWO4nanorod. MnWO4and 1%Ce-MnWO4nanorods were shown to retain their selective oxidation performance in consecutive reaction runs. Surprisingly, physical mixtures of nanostructured MnWO4and a CeO2nanopowder showed enhanced selective oxidation activity compared to MnWO4alone reaching a plateau at 25–50 wt% CeO2, whereas CeO2nanopowder itself was found to be inactive at the reaction conditions. Ce promoted MnWO4shows promise as a catalyst for selective oxidation of cyclohexane and performs at least as well as the most active non-metallic heterogeneous catalysts reported in the literature.
Date Issued
2018-11-25
Date Acceptance
2018-09-26
Citation
Applied Catalysis A: General, 2018, 568 (1), pp.95-104
ISSN
0926-860X
Publisher
Elsevier
Start Page
95
End Page
104
Journal / Book Title
Applied Catalysis A: General
Volume
568
Issue
1
Copyright Statement
© 2018 Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence http://creativecommons.org/licenses/by-nc-nd/4.0/
Sponsor
King Abdulaziz City for Science and Technology (KA
Identifier
https://www.sciencedirect.com/science/article/pii/S0926860X18304861
Grant Number
DHRZEJ0
Subjects
Science & Technology
Physical Sciences
Life Sciences & Biomedicine
Chemistry, Physical
Environmental Sciences
Chemistry
Environmental Sciences & Ecology
Cyclohexane
Selective oxidation
MnWO4
Cerium
KA oil
LIQUID-PHASE OXIDATION
DOPED CERIA
ALKANE OXIDATION
MN
XPS
CATALYSTS
SPECTRA
OXIDES
OXYGEN
0306 Physical Chemistry (incl. Structural)
0904 Chemical Engineering
Physical Chemistry
Publication Status
Published
Date Publish Online
2018-09-29