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Gold-promoted oxidation reactions oxidants

Beside CO oxidation, the gold promoted oxidation of propene is one of the most investigated reactions because of its industrial interest. In fact, the peculiar ability of gold to catalyse the synthesis of propene oxide by using O2 and H2 as reagents... [Pg.438]

The field of gold-catalysed oxidation reactions is clearly dominated by heterogeneous catalysts and many reports have been published on this topic. " Although much less predominant, some examples of efficient homogeneous gold-promoted oxidations using green oxidants have been reported. [Pg.66]

The oxidation of CO is the simplest reaction and has been the most intensively studied since Langmuir first presented a theory of adsorption and catalysis for this reaction [13]. Supported Au NPs such as Au/Ti02, Au/Fe203 and Au/Co304 are extraordinarily active in CO oxidation, even at 200 K, and are much more active than the other noble metals catalysts at temperatures below 400 K [14—16]. Gold clusters composed of several atoms can promote the reaction between CO and 02 to form C02 at as low as 40 K [17]. Most recently, Lahr and Ceyer [18] have extended the temperature range at which the activity for CO oxidation is observed to as low as 70 K by using an Au/Ni surface alloy. [Pg.79]

To focus on the influence of water on the chemical activity of gold in nanocatal3dic reactions, quantum mechanical ab initio calculations were performed [396] for model systems that do not exhibit charging effects originating from excess electrons bound to free An clusters (i.e., gold cluster anions) [33,382,397] or from defects at the metal-oxide surface [209,368] that have been shown, as described in the previous subsections, to promote the... [Pg.132]

An excess of epoxide groups (5/1 mix) promotes chemical bonding at the interface and brings 0q up to the value of Jq for oxide surfaces but only to one-third Jq for gold. This difference between gold and oxide is clearly indicative of a chemical reaction at the interface. [Pg.348]

In our case the chemical composition and, consequently, the structure of the iron oxide is changed with time during reaction. Gold diffusion from film and nanoparticles underneath may occur but seem not to be the decisive factor in promoting the CO oxidation activity. [Pg.101]

It is worth mentioning that both the carboxylation of epoxides and anilines are acid-base reactions, which do not entail redox processes. Therefore a catalyst active in these reactions must provide acid-base functionality. In this perspective, positively charged gold could be the real player, although a co-catalytic or promotion effect of ze-rovalent gold could also be important. Therefore the catalysts for the oxidative carbonylation of aniline, supported on Merck Ion-exchanger IV, could be actually bifunctional. On one side, Au could catalyze the oxidation of CO with O2 to CO2, a reaction for which it is... [Pg.228]

The first set of reactions is the mainstay of the petrochemical industry 1 outstanding examples are the oxidation of propene to propenal (acrolein) catalysed by bismuth molybdate, and of ethene to oxirane (ethylene oxide) catalysed by silver. In general these processes work at high but not perfect selectivity, the catalysts having been fine-tuned by inclusion of promoters to secure optimum performance. An especially important reaction is the oxidation of ethene in the presence of acetic (ethanoic) acid to form vinyl acetate (ethenyl ethanoate) catalysed by supported palladium-gold catalysts this is treated in Section 8.4. Oxidation reactions are very exothermic, and special precautions have to be taken to avoid the catalyst over-heating. [Pg.217]

Oxide ions of the support were shown to participate in the reaction through a Mars-van Krevelen mechanism (Section 1.4), and the supports also acted as structural promoters to stabilise the small gold particles.55... [Pg.295]


See other pages where Gold-promoted oxidation reactions oxidants is mentioned: [Pg.66]    [Pg.412]    [Pg.163]    [Pg.11]    [Pg.214]    [Pg.402]    [Pg.284]    [Pg.482]    [Pg.665]    [Pg.497]    [Pg.869]    [Pg.766]    [Pg.17]    [Pg.215]    [Pg.214]    [Pg.67]    [Pg.305]    [Pg.101]    [Pg.101]    [Pg.347]    [Pg.47]    [Pg.240]    [Pg.242]    [Pg.310]    [Pg.429]    [Pg.223]    [Pg.311]    [Pg.317]    [Pg.186]    [Pg.67]    [Pg.3436]    [Pg.2541]    [Pg.1681]    [Pg.17]    [Pg.42]    [Pg.57]    [Pg.273]   
See also in sourсe #XX -- [ Pg.2 , Pg.68 ]

See also in sourсe #XX -- [ Pg.2 , Pg.68 ]




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Promoters reaction

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