Heterogeneously Catalyzed Oxidation Reactions Using ... - CHEC
Heterogeneously Catalyzed Oxidation Reactions Using ... - CHEC
Heterogeneously Catalyzed Oxidation Reactions Using ... - CHEC
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Chapter 3<br />
Selective Liquid-Phase <strong>Oxidation</strong> of Alcohols<br />
<strong>Catalyzed</strong> by a Silver-Based Catalyst Promoted by<br />
the Presence of Ceria<br />
Abstract<br />
A number of impregnated silver catalysts supported on SiO2,<br />
Al2O3, celite, CeO2, kaolin, MgO and activated carbon were<br />
screened for their catalytic activity in the selective liquid<br />
phase oxidation of benzyl alcohol using a special screening<br />
approach. For this purpose 5‐6 catalyst samples were mixed<br />
and tested simultaneously. When a high catalytic conversion<br />
(> 30 % over 2 h) was found the number of catalyst<br />
1Alcohol oxidation by components was reduced in the following tests. Thereby, a<br />
Ag/SiO2 – CeO2.<br />
collaborative effect between a physical mixture of ceria nanoparticles and silver‐impregnated silica<br />
(10 wt.‐% Ag/SiO2) was found. The catalytic activity was highly dependent on the silver loading, the<br />
amount of ceria and especially the calcination procedure. Transmission electron microscopy (TEM),<br />
X‐ray diffraction (XRD) and X‐ray absorption spectroscopy (XANES, EXAFS) demonstrate that silver is<br />
mainly present as metallic particles. This is also supported by in situ XAS experiments. Silver‐oxygen<br />
species appear to be important for the catalytic oxidation of the alcohol for which a preliminary<br />
mechanism is presented. The application of the catalyst was extended to the oxidation of a wide<br />
range of primary and secondary alcohols. Compared to Pd and Au catalysts, the new Ag catalyst<br />
performed similarly or even superior if CeO2 was present. In addition, the presence of ceria increased<br />
the catalytic activity of all investigated catalysts.<br />
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