Oxidation catalytic, of hydrocarbons

Fumaric acid is used in the plastics industry, in the food industry and as a source of malic add. Although demand has increased rapidly over the last 30 years its production from fermentation has been totally replaced by a chemical method. It is now produced far more cheaply by the catalytic oxidation of hydrocarbons, particularly benzene. With the continuing uncertainties concerning the availability and cost of petroleum, however, fermentation may yet be a viable alternative. 

What can all these studies suggest to the inorganic chemist interested in the controlled and fAcile catalytic oxidation of hydrocarbons Groves and coworkers have already shown that iron porphyrins in the presence of iodosylbenzene and peracids can be used for such catalytic reactions (37, 38). However, the cost of the oxidants makes such reaction uneconomical at this time. 

A mechanism for the catalytic oxidation of hydrocarbons is due to Mars Van Krevelen (Spec Suppl Chem Eng Sci 3 41, 19541. These assumptions are made ... 

Biphasic Catalytic Oxidation of Hydrocarbons Using Immobilized Homogeneous Catalyst in a MicroChannel Reactor 91... 

Ionization from the Heterogeneous Catalytic Oxidation of Hydrocarbons in the Vapor Phase... 

Andersson developed a semi-empirical model for the charge distribution around the (V=0) bonds in V205, V6013, and V02.73 The surfaces of the lower oxides were treated, upon the basis of ESCA results discussed on p. 107, as being in an oxidized state, which is proposed to be the case under the usual conditions in (amm) oxidation reactions. The main result is that 02-in the form of (V=0) groups is responsible for the catalytic oxidation of hydrocarbons. 

The classic method for carrying out catalytic oxidations of hydrocarbon substrates has involved the use of the hydrocarbon itself as solvent and trace amounts of hydrocarbon-soluble metal complexes, such as metal stearates, naph-thenates, or acetylacetonates, as catalysts. These reactions were generally carried out to low conversions to avoid excessive by-product formation. Catalysis involved redox reactions of the metal catalyst with intermediate hydroperoxides. 

These effects have been observed by Margolis and co-workers in their detailed kinetic study of the catalytic oxidation of hydrocarbons (219-222). The extensive oxidation of hydrocarbons to carbon dioxide over catalysts of the spinel type has been studied by a number of investigators. It was possible for Margolis and co-workers to establish the effect of additives upon the basic kinetic constants, namely the activation energy of oxidation and the frequency factor for this reaction. 

An oxidized surface state model of vanadium oxides and its application to catalysis have been discussed by A. Andersson [J. Solid Slate Chem. 42, 263 (1982)]. The author concludes that O2" ions, in the form of V=0 surface groups, are responsible for the catalytic oxidation of hydrocarbons. 

The catalytic oxidation of hydrocarbons with peroxides, especially the epoxidation of olefins, in liquid phase by titanium catalysts is one of the most actively investigated reactions (60). The active species for this epoxidation reaction is usually assumed to be titanium peroxo moieties, derived from four-coordinate titanium and peroxides. However, the isolation of the active intermediate remains a challenge owing to the inherent instability of such species. We have been able to synthesize and stabilize the related cubic p-oxo-silicon-titanium complex (35) by reacting a bulky... 

A number of bismuth/metal oxides are used in the catalytic oxidation of hydrocarbons, and in the oxidation and ammoxidation of alkenes These transformations are described briefly in Bismuth Inorganic Chemistry. 

Ainmoxidation, sometimes also termed oxidative ammonolysis, describes the process of catalytic oxidation of hydrocarbons (particularly alkenes, alkanes, alkyl-aromatics and alkyl-pyridines) to organic nitriles in the presence of ammonia, typically using mixed oxide catalysts ... 

In short, catalytic oxidation of hydrocarbons is a structure-sensitive reaction, and its mechanism is strongly dependent on the type of catalyst and on process conditions. This means that the morphology of the active phase will affect the catalyst activity, and hence the preparation procedure will have a strong influence on catalyst performance. 

The detoxification of hydrocarbon pollutants is one of the global environmental challenges [531-533]. The complete catalytic oxidation of hydrocarbons to carbon dioxide and water has received much attention in order to reduce their emission from motor vehicles and processing plants [531,533,534]. 

The oxidation of gaseous hydrocarbons over solid catalysts has been the subject of extensive industrial and academic research for many years. The mutual interest in these reactions reflects both their commercial importance and their value in studies of the fundamental features of catalytic processes. Indeed, the source of several theoretical investigations of catalytic reactions may readily be traced to developments in the modern chemical industry. Moreover, the numerous studies that have been conducted are a further reflection of the diversity of scientific interests embodied in this subject and the wide range of techniques currently available for their investigation. It is not surprising, therefore, that the heterogeneous catalytic oxidation of hydrocarbons is a subject in which a wealth of data has been accumulated and a diversity of opinions recorded. Hence, it is inevitable that in an article of this type any worthwhile inquiry into such a large field of scientific interest requires the consideration of a restricted aspect of the subject. 

Tolrnan, C.A., and Herron, N. 1988. The selective catalytic oxidation of hydrocarbons in zeolites under mild conditions. Catal is is Today 3, 235-243. 

Margolis, L. J., Heterogeneous Catalytic Oxidation of Hydrocarbons. Gostop-tehizdat, Moskwa, 1962. 

Figure 1. Mechanism of the catalytic oxidation of hydrocarbons. Reproduced with permission from Ref. 31.

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