Oxidation atomic oxygen

The overall selectivity for oxidation depends not only on the composition of the catalytic material, but also on the type of active oxygen species that are present at the surface. Oxygen on the surface can exist in various different forms ranging from adsorbed O2 to fully oxidized atomic oxygen (O ) as is shown in the Eq. (5.1) below [29-32]... 

Ozone makes up about 90% of a general class of secondary pollutants called the oxidants. Atomic oxygen and ozone can react with the lower hydrocarbons to produce a large variety of oxidants. Principal among these are... 

The product (6 hexanohde) is a cyclic ester or lactone (Section 19 15) Like the Baeyer-Vilhger oxidation an oxygen atom is inserted between the carbonyl group and a carbon attached to it But peroxy acids are not involved m any way the oxidation of cyclohexanone is catalyzed by an enzyme called cyclohexanone monooxygenase with the aid of certain coenzymes... 

Oxidation. AH inorganic siUcon hydrides are readily oxidized. Silane and disilane are pyrophoric in air and form siUcon dioxide and water as combustion products thus, the soot from these materials is white. The activation energies of the reaction of silane with molecular and atomic oxygen have been reported (20,21). The oxidation reaction of dichlorosilane under low pressure has been used for the vapor deposition of siUcon dioxide (22). 

Effect of Thermal History. Many of the impurities present in commercial copper are in concentrations above the soHd solubihty at low (eg, 300°C) temperatures. Other impurities oxidize in oxygen-bearing copper to form stable oxides at lower temperatures. Hence, because the recrystallization kinetics are influenced primarily by solute atoms in the crystal lattice, the recrystallization temperature is extremely dependent on the thermal treatment prior to cold deformation. 

Now we find that nitrogen dioxide can be formed from a mixture of nitric oxide and oxygen. This means that the atoms in nitrogen dioxide must have come from those in nitric oxide together with those in oxygen. 

PdF6 has been reported [19] (but not confirmed) to result from the reaction of powdered palladium with atomic fluorine under pressure (900-1700 Pa) as a dark red solid, unstable at 0°C that oxidizes both oxygen and water. An IR band at 711 cm-1 has been assigned as i/(Pd-F). There are unsubstantiated claims for PdF5. 

It is concluded [634] that, so far, rate measurements have not been particularly successful in the elucidation of mechanisms of oxide dissociations and that the resolution of apparent outstanding difficulties requires further work. There is evidence that reactions yielding molecular oxygen only involve initial interaction of ions within the lattice of the reactant and kinetic indications are that such reactions are not readily reversed. For those reactions in which the products contain at least some atomic oxygen, magnitudes of E, estimated from the somewhat limited quantity of data available, are generally smaller than the dissociation enthalpies. Decompositions of these oxides are not, therefore, single-step processes and the mechanisms are probably more complicated than has sometimes been supposed. 

Malinin et al. [634,647] have studied rates of decompositions of lead oxides. The reaction of Pb304 at 840 K yields some 15% atomic oxygen, obeys the Avrami—Erofe ev equation [eqn. (6), n = 2] and values of E are 320 and 190 kJ mole-1 at atmospheric pressure and in vacuum, respectively. 

Equations for the Standard Free Energy of Formation and Partial Molar Free Energies of Atomic Oxygen for Plutonium Oxides (1600-2150 K), cal/mol... 

For A l, the Faradaic efficiency A has, as already noted, an interesting physical meaning50 For oxidation reactions it expresses the ratio of the reaction rates of normally chemisorbed atomic oxygen on the promoted... 

Similarly to the case of C2H4 oxidation on Pt (section 8.1.1.1) one can attribute this decrease to the increased entropy of chemisorbed atomic oxygen due to the weakening of the Ag=0 bond with increasing work function O. 

Good Thermal and Oxidative Stability High Permeability to Gases Excellent Atomic Oxygen (Plasma) Resistance Physiological Inertness (Biocompatibility)... 

The elementary reaction energies and thermodynamics for methanol dehydrogenation have been shown to be significantly influenced by electrode potential. The oxidation pathways become much more favorable at higher potentials. The relative barriers of O—H to C—H bond activation decrease with increasing potential, which decreases the overall selectivity to CO and CO2 and increases the yield of formaldehyde. This is consistent with experimental studies. The oxidation of CO intermediates appears to occur via adsorbed hydroxyl intermediates. The hydroxyl intermediates are more weakly held to the surface than atomic oxygen, and thus have significantly lower barriers for the oxidation of CO. 

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