Oxidation of Cyclohexene Catalyzed by Nanoporous Au(Ag) in Liquid Phase

Nanoporous gold with minor silver content has been identified as a new type of gold based catalyst for selective oxidation of cyclohexene with molecular oxygen in liquid. By oxidation of the leached nanoporous gold foils in ozone, the minor silver content was oxidized to form silver oxide nanocluste...

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Bibliographic Details
Published in:Catalysis letters 2017-02, Vol.147 (2), p.442-452
Main Authors: Dou, Jian, Tang, Yu, Nguyen, Luan, Tong, Xiao, Thapa, Prem S., Tao, Franklin Feng
Format: Article
Language:English
Subjects:
Catalysis
Chemistry
Chemistry and Materials Science
Cyclohexene
Gold
Gold base alloys
Industrial Chemistry/Chemical Engineering
Ligaments
Liquid phases
Metal foils
Methanol
Organic chemistry
Organometallic Chemistry
Oxidation
Oxygen
Ozone
Physical Chemistry
Selectivity
Silver base alloys
Surface alloying
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Summary:Nanoporous gold with minor silver content has been identified as a new type of gold based catalyst for selective oxidation of cyclohexene with molecular oxygen in liquid. By oxidation of the leached nanoporous gold foils in ozone, the minor silver content was oxidized to form silver oxide nanoclusters on the surface of nanoporous gold. With further treatment in methanol, the surface silver oxide was reduced and surface alloy was formed on gold ligaments. Both nanoporous gold treated with ozone only and the one with ozone and then methanol are very active for selective oxidation of cyclohexene with molecular oxygen in liquid of cyclohexene with a turn-over-frequency (TOF) of 0.55–0.99 molecules per surface Au atom per second under a solvent-free and initiator- free condition. The total selectivity for production of 2-cyclohexene-1-one, 2-cyclohexene-1-ol, and cyclohexene oxide was increased from 57.5 % to 80.8 % by an additional treatment of nanoporous gold in methanol after activation in zone. The correlation of catalytic selectivity for the production of the three products and corresponding surface chemistry of ligament suggests that (1) the formed Au–Ag alloy surface is favorable for the formation of 2-cyclohexen-1-one, 2-cyclohexene-1-ol, and cyclohexene oxide and (2) the surface silver oxide is favorable for the production of cyclohexenyl hydroperoxide. Graphical Abstract
ISSN:1011-372X
1572-879X
DOI:10.1007/s10562-016-1883-6