Oxidation reactions, alkanes

Although essentially inert m acid-base reactions alkanes do participate m oxidation-reduction reactions as the compound that undergoes oxidation Burning m air (combus tion) IS the best known and most important example Combustion of hydrocarbons is exothermic and gives carbon dioxide and water as the products... 

Precious Meta.1 Ca.ta.lysts, Precious metals are deposited throughout the TWC-activated coating layer. Rhodium plays an important role ia the reduction of NO, and is combiaed with platinum and/or palladium for the oxidation of HC and CO. Only a small amount of these expensive materials is used (31) (see Platinum-GROUP metals). The metals are dispersed on the high surface area particles as precious metal solutions, and then reduced to small metal crystals by various techniques. Catalytic reactions occur on the precious metal surfaces. Whereas metal within the crystal caimot directly participate ia the catalytic process, it can play a role when surface metal oxides are influenced through strong metal to support reactions (SMSI) (32,33). Some exhaust gas reactions, for instance the oxidation of alkanes, require larger Pt crystals than other reactions, such as the oxidation of CO (34). 

Oxidative reactions frequently represent a convenient preparative route to synthetic intermediates and end products This chapter includes oxidations of alkanes and cycloalkanes, alkenes and cycloalkenes, dienes, aromatic fluorocarbons, alcohols, phenols, ethers, aldehydes and ketones, carboxylic acids, nitrogen compounds, and organophosphorus, -sulfur, -selenium, -iodine, and -boron compounds... 

Trifluoroacetic acid is a useful medium for a number of oxidation reactions It IS highly resistant to strong oxidants, even to permanganates and chromates For instance, various alkanes, cycloalkanes, and arenes can be oxidized degradatively by potassium permanganate in trifluoroacetic acid under mild conditions [28]... 

In the same spirit DFT studies on peroxo-complexes in titanosilicalite-1 catalyst were performed [3]. This topic was selected since Ti-containing porous silicates exhibited excellent catalytic activities in the oxidation of various organic compounds in the presence of hydrogen peroxide under mild conditions. Catalytic reactions include epoxidation of alkenes, oxidation of alkanes, alcohols, amines, hydroxylation of aromatics, and ammoximation of ketones. The studies comprised detailed analysis of the activated adsorption of hydrogen peroxide with... 

Fe-Catalyzed Oxidation Reactions of Olefins, Alkanes, and Alcohols Involvement of Oxo- and Peroxo Complexes... 

The large amounts of natural gas (mainly methane) found worldwide have led to extentive research programs in the area of the direct conversion of methane [1-3]. Ihe oxidative transformation of methane (OTM) is an important route for the effective utilization of the abundant natural gas resources. How to increase catalyst activity is a common problem on the activation of methane. The oxidation of methane over transition m al oxides is always high active, but its main product is CO2, namely the product of deep oxidation. It is because transition metal oxides have high oxidative activity. So, they were usually used as the main corrqtonent of catalysts for the conqilete oxidation of alkane[4]. The strong oxidative activity of CH4 over tran on metal oxides such as NiO indicates that the activation of C-H bond over transition metal oxides is much easier than that over alkaline earth metal oxides and rare earth metal oxides. Furthermore, the activation of C-H bond is the key step of OTM reaction. It is the reason that we use transition metal oxides as the mam conq>onent of the OTM catalysts. However, we have to reahze that the selectivity of OTM over transition metal oxides is poor. 

TS-1 is a material that perfectly fits the definition of single-site catalyst discussed in the previous Section. It is an active and selective catalyst in a number of low-temperature oxidation reactions with aqueous H2O2 as the oxidant. Such reactions include phenol hydroxylation [9,17], olefin epoxida-tion [9,10,14,17,40], alkane oxidation [11,17,20], oxidation of ammonia to hydroxylamine [14,17,18], cyclohexanone ammoximation [8,17,18,41], conversion of secondary amines to dialkylhydroxylamines [8,17], and conversion of secondary alcohols to ketones [9,17], (see Fig. 1). Few oxidation reactions with ozone and oxygen as oxidants have been investigated. 

Au "=0 species are postulated, inter alia, as active intermediates in the oxidation of alkanes with hydrogen peroxide catalyzed by gold(III) and gold(I) complexes [115]. The reaction sequence is proposed in Scheme 2.8. 

The most extensive studies of alkane reactions in aqueous media are on the oxygenation reaction. In fact, nature has used monooxygenase (found in mammalian tissue) and other enzymes to catalyze the oxidation of alkanes to give alcohols in aqueous environments at ambient... 

Ceria-based OSC compounds may have an impact on oxidation reactions especially when the catalysts are working around the stoichiometry (as this is the case under TW conditions). One of the first systematic studies was reported by Yu Yao [53,54], Most results were obtained in 02 excess (0.5% CO + O.5% 02 or 0.1% HC+ 1% 02). Several series of Pt, Pd and Rh/Al203 of various dispersion, as well as metal foils, were investigated in CO, alkane and alkene oxidation. The effect of metal dispersion in CO and the propane oxidation are shown in Figure 8.5. 

This catalyst can catalyze a new reaction, called alkane metathesis. By this reaction, alkanes are transformed into higher and lower alkanes.265 Silica-supported zirconium catalysts were also used for the mild oxidation of alkenes by H202 266... 

The streaking in the ED provides important evidence of the structural disorder attributed to the defects in (201) planes. This means that anions in (201) planes, located between vanadyl octahedra and phosphate tetrahedral, are involved in the alkane oxidation reaction. The disorder attributed to the catalyst anion loss is revealed only in (201) lattice planes, thus excluding all other planes in the crystal structure. 

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