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Nobel metal free, oxidant free, solvent free catalytic transformation of alcohol to aldehyde over ZnO-CeO2 mixed oxide catalyst

Paper ID Volume ID Publish Year Pages File Format Full-Text
38748 45790 2016 10 PDF Available
Title
Nobel metal free, oxidant free, solvent free catalytic transformation of alcohol to aldehyde over ZnO-CeO2 mixed oxide catalyst
Abstract

•Noble metal free catalyst for alcohol dehydrogenation.•Reaction in Oxidant free condition.•Formation of alkanes from primary alcohol.•No mass transfer limitation.

The catalytic transformation of alcohols to aldehydes under oxidant-free condition has drawn significant attention from the perspective of green chemistry. In this work, we designed noble metal free ZnO-CeO2 mixed oxide catalyst in four different ratios and tested for vapor phase benzyl alcohol dehydrogenation reaction as a model reaction under oxidant free condition. The ZnO-CeO2 mixed oxide catalyst having ratio Zn/Ce = 30/70 composition showed highest selectivity towards formation of benzaldehyde. Interestingly in addition to benzaldehyde, toluene was formed in the reaction due to hydrogenolysis of benzyl alcohol. The lowest Ce3+/Ce4+ ratio was observed from the XPS analysis of Ce(3d) core electron for the catalyst having Zn/Ce = 30/70 composition compared to others. CO2-TPD results proved that mostly the medium strength basic sites were responsible for hydrogen abstraction from benzyl alcohol producing benzaldehyde. H2-TPR results showed that ZnO-CeO2 catalyst (Zn/Ce = 30:70) had lowest reduction temperature which is in the 673 K to 573 K temperature range. The amount of toluene was higher for the ZnO-CeO2 catalyst having Zn/Ce = 40:60 ratio which had less basic sites and higher fraction of Ce3+ ion. The ZnO-CeO2 catalyst (Zn/Ce = 30:70) did not deactivate for a reaction time up to 2 h. While successive regenerations of the catalyst, toluene selectivity were increased. This may be due to the reduction of Ce4+ to Ce3+ by adsorbed hydrogen species. Also the ZnO-CeO2 catalyst (Zn/Ce = 30/70) showed activity for the formation of ethanal, propanal, butanal and octanal along with corresponding alkanes from ethanol, 1-propanol, 1-butanol and 1-octanol in oxidant free condition demonstrating the in-situ generation of hydrogen. The micro kinetic analysis showed that there is no external and internal mass transfer limitation in the present case.

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Keywords
Dehydrogenation; Benzyl alcohol; Propane; Zinc; Ceria; Toluene
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Nobel metal free, oxidant free, solvent free catalytic transformation of alcohol to aldehyde over ZnO-CeO2 mixed oxide catalyst
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 523, 5 August 2016, Pages 21–30
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us