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Pt/C and PtBi/C catalysts prepared on a synthetic mesoporous carbon were evaluated in the oxidation of secondary aromatic alcohols (1-phenylethanol, α-methyl or phenyl pyridinemethanol) with air in different dioxane/water mixtures at 100 °C under 10 bar air. The observed activity for all substrates over both types of catalysts was strongly improved with the addition of water to the dioxane solvent as a result of different interactions of the alcohols with the metallic surface in the apolar dioxane solvent or polar aqueous medium. A promoting effect of bismuth was observed for all substrates. However, the reaction rate was also dramatically influenced by the nature of the aromatic moiety, the nature of the α-group, and the position of the substituent on the pyridine moiety. As a general rule the reactivity was meta

Bernardi, Marco Cretenot, Didier Deleris, Stephane Descorme, Claude Chauzy, Julien Besson, Michele 6th World Congress on Oxidation Catalysis (6WCOC) JUL 05-10, 2009 Lille, FRANCE; International audience; Various soluble transition metal salts were compared in the wet air oxidation of industrial and municipal sewage sludges (2 5-25 g L-1 total organic carbon) at 200-250 degrees C under 4-15 bar O-2 partial pressure The evolution of the TOC content in both the liquid and solid phases and the overall TOC conversion were monitored While copper sulphate prevented the dissolution of the suspended organic matter due to strong bounding of copper to a fraction of the organic matter in sludge and showed high activity in the mineralization of the solubilized organic compounds (liquid phase) the implementation of iron sulphate resulted in a higher transfer of the organic matter to the liquid phase but in a moderate activity in the oxidation of solubilized molecules When used in combination a synergetic effect between these two salts was evidenced (C) 2010 Elsevier BV All rights reserved

This paper gives three examples of applications of activated carbons, including synthetic carbons obtained from polymers, in selective liquid phase organic reactions. It is shown that ruthenium supported on activated carbon cloths (ACC) obtained by carbonisation of woven rayon fabric are very selective in the hydrogenation of glucose to sorbitol. This is attributed to an easy mass transfer from the micropores to the liquid phase which favours the fast desorption of sorbitol avoiding epimerisation to mannitol. Synthetic carbons obtained by carbonisation of cross-linked phenolic resins are active in the oxidation with air of cyclic ketones (cyclohexanone, cyclododecanone, 3,3,5-trimethylcyclohexanone) to the corresponding dicarboxylic acids. The activity and selectivity depend upon treatments favouring the presence of surface functional groups, particularly quinone/carbonyl groups. This paper also shows that activated carbons obtained from natural sources can be modified by thermal treatments favouring the presence of basic sites which improve the rate of the oxidative decarboxylation of N-phosphonomethyl iminodiacetic acid to glyphosate. The nitrogen-containing basic functions generated by high temperatures thermal treatment of the activated carbon in NH3 are particularly active.

Oxidation of aldehydes, alcohols or carbohydrate derivatives can be performed with air in aqueous media, in the presence of palladium and platinum catalysts under mild conditions (293–353 K and atmospheric pressure). These reactions provide valuable products and intermediates for fine chemistry. They have been known for a long time, but much effort in the last 20 years has focused on this approach, because these catalytic reactions are environmentally friendly and could replace stoichiometric oxidations with mineral oxidizing agents. An oxidative dehydrogenation mechanism on the reduced metal surface has been generally accepted. During this process, a strong deactivation of the catalysts is often reported, which is a cause of serious concern for process development. Several causes of deactivation have been put forward: oxidation of metal, blocking of active sites by strong adsorption of side-products, metal leaching and growth of platinum crystallites. The addition of certain p-electron metal promoters (e.g. Bi, Pb) has been shown to play a useful dual role in reducing catalysts deactivation and in changing the selectivity of reactions. The performances of the catalysts can also be improved by modification of the metallic surface with strongly adsorbing nitrogen-containing bases or phosphines. A few illustrative examples will be given, which show that carbohydrates, aliphatic or aromatic alcohols, and polyols can be oxidized with high selectivities into valuable products.