Selective Oxidation Liquid Phase

The activity of elemental carbon as a metal-free catalyst is well established for a couple of reactions, however, most literature still deals with the support properties of this material. The discovery of nanostructured carbons in most cases led to an increased performance for the abovementioned reasons, thus these systems attracted remarkable research interest within the last years. The most prominent reaction is the oxidative dehydrogenation (ODH) of ethylbenzene and other hydrocarbons in the gas phase, which will be introduced in a separate chapter. The conversion of alcohols as well as the catalytic properties of graphene oxide for liquid phase selective oxidations will also be discussed in more detail. The third section reviews individually reported catalytic effects of nanocarbons in organic reactions, as well as selected inorganic reactions. 

Supported Polyoxometalate-Based Heterogeneous Catalysis for Liquid Phase Selective Oxidations... 

Polyoxometalates undoubtedly have enormous catalytic potential in liquid phase selective oxidation of organic compounds. Various strategies for immobilization of POMs on solid matrices have been developed during the past two decades and opened new opportunities for practical applications. The most developed and widely used technique is electrostatic... 

Liquid-Phase Selective Oxidation of Organic Compounds... 

Liquid-phase selective oxidations are of industrial importance for fine chemical syntheses. However, stoichiometric oxidizing agents have been mostly used and the generation of unwanted by-products exceeds that of desired products in quantity. To... 

Liquid-phase selective oxidations are normally catalysed homogeneously. A small but significant interest has recently arisen in the use of solid catalysts for liquid-phase oxidation, particularly of alkyl aromatics. Shalya et al. have compared the activity of copper, silver, and gold metals as catalysts for cumene oxidation (Table 2). Silver was found to combine good selectivity for the desired product, cumene hydroperoxide, with an activity similar to that of copper. With supported catalysts, silver is considerably more active than copper, while gold is totally inactive. 

Here, our recent work on the synthesis and liquid-phase selective oxidation catalysis of y-SiW o Fe(OH2) 2038 with molecular oxygen is mainly described. ... 

Liquid phase selective oxidations of propylene over TS-1 have also been achieved [153, 154] but while Laufer and Hoelderich extended their TS-l/propylene work to include epoxidations of styrene and pinene over a Ti-MCM-41-based catalyst [155], in situ epoxidation reactions of more complex alkenes than propylene remain poorly documented and have yet to attain the industrially relevant success of TS-1-based catalysts in selective oxidations of even simple alkenes. 

Liquid-phase selective oxidation using hydrogen peroxide and heterogeneous catalysts is of significant interest to both the fine chemical and pharmaceutical industries. Heterogeneous catalytic oxidation is, in many situations, an advanced oxidation process (AOPs). In this case, the chemical oxidation processes occur in the presence of oxidants able to generate hydroxyl radicals ( OH) [46]. An example is the remarkable success of Fenton reagent for phenol oxidation. 

One of the most important industrial achievements in the field of liquid-phase selective oxidation has been the discovery of titanium silicalite-1 (TS-1) at Eni in the late 1970s, by Taramasso and co-workers. Thanks to the unique reactivity properties of TS-1, several innovative processes that use hydrogen peroxide are now industrial processes, and others are under advanced development. 

The liquid-phase selective oxidation of hydrocarbons is a wide area of research, and relevant heterogeneously-catalysed industrial processes are mostly carried out with mixed oxides or ordered porous catalytic systems, which escape the scope of this chapter. For a more comprehensive survey of the industrial and technological developments within industrial liquid-phase oxidation reactions, we recommend generic literature, in particular the Handbook of Heterogenous Catalysis and recent reviews on oxidation with with transition-metal complexes by Bregeault et al and Punniyamurthy. However, from a more academic perspective, there has been significant progress in this research area which we describe below, in sections divided on the basis of the substrate of the reaction. 

Liotta, L., Venezia, A., Deganello, G., etal (2001). Liquid Phase Selective Oxidation of Benzyl Alcohol over Pd-Ag Catalysts Supported on Pumice, Catal Today, 66, pp. 

Liquid-Phase Selective Oxidation by Multimetallic Active Sites of Polyoxometalate-Based Molecular Catalysts... 

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