Lattice oxygen chemical nature

Lateral polymerization model, 30 169-170 Lattice oxygen, 27 191, 32 118-121 chemical nature of, 27 195, 196 role of, 27 191-195 Lattice parameters, Cn/ZnO, 31 247 Layer lattice silicates, catalysts, 39 303-326 catalyst solution immobilization, 39 319-324 2-6-di-fert-butylphenoI liquid-phase oxidation on Cu -TSM, 39 322-324 propylene gas-phase oxidation on Cu Pd -TSM, 39 320-322 materials, 39 305-307 metal ion-exchanged fluorotetrasilicic mica, 39 306-308... 

Solid-state diffusion, which is involved in the release of oxygen, proceeds generally through the movement of point defects. The vacancy mechanism, the interstitial mechanism, and the interstitialcy mechanism can occur depending on the distortion of the solid lattice and the nature of the diffusing species. When one of the steps 1-5 is the slowest step representing the major resistance, that step is the rate-controlling one, which is not necessarily the chemical reaction (step 3). 

Efficient Photochemical Water Splitting by a Chemically Modified n-Ti02. Combustion of Ti metal in a natural gas flame done to substitute carbon for some of the lattice oxygen sites. The photocatalysis performance data have been questioned (see Refs. 214-216). 213... 

Some of the oxides of vanadium and molybdenum catalyze the selective oxidation of hydrocarbons to produce valuable chemical intermediates. In a reaction path proposed by Mars and van Krevelen (see Section 10.5), the hydrocarbon first reduces the surface of the metal oxide catalyst by reaction with lattice oxygen atoms. The resulting surface vacancies are subsequently re-oxidized by gaseous O2. The elementary steps of this process are shown below. Electrons are added to the sequence to illustrate the redox nature of this reaction. 

At low temperatures where the surface ionic mobility is restricted the catalytic activity of a divided oxide for oxidation or reduction processes is determined primarily by the nature and the concentration of lattice defects in the surface layer and by the strength of the bond between oxygen and these defects. The nature and concentration of the defects depend upon the chemical nature of the catalyst, its previous history, and on the course of the catal diic reaction itself. In some instances, a small modification in the preparation procedure or in the pretreatment may result in an important change of cataljrtic activity. Such abrupt changes of activity may be caused by the occurrence of different reaction paths on apparently similar catalysts. Since the catalytic act is localized on particular surface structures, the energy spectrum of the active surface is of paramount importance and correlations between catal3rtic activities and collective or average properties of the catalyst are crudely approximate. 

Fig. 5 Montage image combining an STM image of the Ag oxide structure (from bottom left) superimposed over the proposed oxide structure (from top right). The numbers, n = 1-5, correspond to the symmetrically different positions within the middle silver layer sandwiched between two O layers. Agi and Ag2 have metallic character, as they are exclusively bonded to silver atoms in the substrate below, whereas Ags, Ag4, and Ags are directly bonded to oxygen inside the oxide rings and are ionic in nature. Both Ag4 and Ags sites sit above threefold sites of the underlying (111) lattice atoms, whereas Ags occupies a top site. Reprinted with permission from Bocquet et at.. Journal of the American Chemical Society, 2003, 125, 3119. 2003, American Chemical Society.

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