Oxidation on solid

NO can be oxidized or reduced on an electrode surface. Since the reduction potential of NO is close to that of oxygen which causes huge interference NO measurement, therefore, usually oxidation of NO is used for measurement of NO. NO oxidation on solid electrodes proceeds via an EC mechanism electrochemical reaction [22] followed by chemical reaction [23], First, one-electron transfer from the NO molecule to the electrode occurred and resulted in the formation of a cation ... 

The Mechanism of Carbon Monoxide Oxidation on Solid Oxides.. 243... 

Our own experience with reactions on crystal surfaces has been confined to oxidations on solid KMnO, and NaMnO, (12). The work began with a curious observation in conflict with literature statements. We found that solid KMnO, stirred with a benzene solution of a secondary alcohol would oxidize the alcohol to a ketone. 

Kerr, W. J., Lindsay, D. M. Preparation of an amine N-oxide on solid phase an efficient promoter of the Pauson-Khand reaction. Chem. Common. 1999, 2551-2552. 

Centi, G., Stella, G. Synthesis of 2-butanone by selective oxidation on solid Wacker-type catalysts. Chem. Ind. 1995, 62, 319-329. 

The goal of maximum energy generation by oxidation of carbonaceous species often thwarted detailed examination of occasional selective oxidations, such as ethylene oxidation to acetaldehyde on Pd or Au (28, 29, 370) or to ethylene oxide on Ag (330) or methanol and benzyl alcohol oxidation to formates and benzaldehyde, respectively (6-32, 54, 250, 333). Product yields were usually determined at one potential only or even galvanostatically (330), and the combined effects of potential, catalyst, reactant concentration, and cell design or mixing on reaction selectivity are unknown at present. Thus, reaction mechanisms on selective electrocatalysis are not well understood with few exceptions. For instance, ethylene oxidation on solid pal-... 

The short life of NO and its low concentration in biological systems make the measurement of this molecule a challenging analytical problem. Among several methods (biochemical assays, UV-Visible spectroscopy, chemiluminescence, EPR) electrochemical methods are considered to be the most suitable for in situ detection of NO in biological milieu. " Generally, the electrochemical oxidation of nitric oxide on solid electrodes proceeds via a two-step (EC mechanism) with an electrochemical reaction as the initial step (heterogenous electron transfer) followed by a chemical reaction. The first electrochemical step is a one-electron transfer from a NO molecule to the electrode residting in the formation of a nitrosonium ion ... 

Burch, R. and Hayes, M.J. H-bond activation in hydrocarbon oxidation on solid catalysts. J. Mol. Catal A Chem. 1995,100, 13-33. 

Corrosion protection of metals can take many fonns, one of which is passivation. As mentioned above, passivation is the fonnation of a thin protective film (most commonly oxide or hydrated oxide) on a metallic surface. Certain metals that are prone to passivation will fonn a thin oxide film that displaces the electrode potential of the metal by +0.5-2.0 V. The film severely hinders the difflision rate of metal ions from the electrode to tire solid-gas or solid-liquid interface, thus providing corrosion resistance. This decreased corrosion rate is best illustrated by anodic polarization curves, which are constructed by measuring the net current from an electrode into solution (the corrosion current) under an applied voltage. For passivable metals, the current will increase steadily with increasing voltage in the so-called active region until the passivating film fonns, at which point the current will rapidly decrease. This behaviour is characteristic of metals that are susceptible to passivation. 

An effect which is frequently encountered in oxide catalysts is that of promoters on the activity. An example of this is the small addition of lidrium oxide, Li20 which promotes, or increases, the catalytic activity of dre alkaline earth oxide BaO. Although little is known about the exact role of lithium on the surface structure of BaO, it would seem plausible that this effect is due to the introduction of more oxygen vacancies on the surface. This effect is well known in the chemistry of solid oxides. For example, the addition of lithium oxide to nickel oxide, in which a solid solution is formed, causes an increase in the concentration of dre major point defect which is the Ni + ion. Since the valency of dre cation in dre alkaline earth oxides can only take the value two the incorporation of lithium oxide in solid solution can only lead to oxygen vacaircy formation. Schematic equations for the two processes are... 

Very high pH values are necessary for the reaction in Eq. (4-1), which can only arise as a result of cathodic polarization according to Eq. (2-19) (see Fig. 2-11). No protective films are formed on Fe due to the relatively high solubility of Fe(OH)2, although further oxidation produces solid films ... 

Figure 5 Solid state NMR spectra of Vanadium oxide on y-alumina as a function of vanadium loading (wt.%) and surface coverage 0. Note the gradual emergence of the six-coordinated vanadium site with increased loading.

The measures of solid state reactivity to be described include experiments on solid-gas, solid-liquid, and solid-solid chemical reaction, solid-solid structural transitions, and hot pressing-sintering in the solid state. These conditions are achieved in catalytic activity measurements of rutile and zinc oxide, in studies of the dissolution of silicon nitride and rutile, the reaction of lead oxide and zirconia to form lead zirconate, the monoclinic to tetragonal transformation in zirconia, the theta-to-alpha transformation in alumina, and the hot pressing of aluminum nitride and aluminum oxide. 

Consider the reaction for the burning of magnesium to form magnesium oxide. Magnesium metal and magnesium oxide are solids. They have the formulas Mg and MgO, respectively. In preparation for writing the equation, we write the formulas for the reactants on the left and the formula for the product on the right ... 

Solid catalysts for the metathesis reaction are mainly transition metal oxides, carbonyls, or sulfides deposited on high surface area supports (oxides and phosphates). After activation, a wide variety of solid catalysts is effective, for the metathesis of alkenes. Table I (1, 34 38) gives a survey of the more efficient catalysts which have been reported to convert propene into ethene and linear butenes. The most active ones contain rhenium, molybdenum, or tungsten. An outstanding catalyst is rhenium oxide on alumina, which is active under very mild conditions, viz. room temperature and atmospheric pressure, yielding exclusively the primary metathesis products. 

The catalytic activity of doped nickel oxide on the solid state decomposition of CsN3 decreased [714] in the sequence NiO(l% Li) > NiO > NiO(l% Cr) > uncatalyzed reaction. While these results are in qualitative accordance with the assumption that the additive provided electron traps, further observations, showing that ZnO (an rc-type semi-conductor) inhibited the reaction and that CdO (also an rc-type semi-conductor) catalyzed the reaction, were not consistent with this explanation. It was noted, however, that both NiO and CdO could be reduced by the product caesium metal, whereas ZnO is not, and that the reaction with NiO yielded caesium oxide, which is identified as the active catalyst. Detailed kinetic data for these rate processes are not available but the pattern of behaviour described clearly demonstrates that the interface reactions were more complicated than had been anticipated. 

M. Stoukides, and C.G. Vayenas, The effect of electrochemical oxygen pumping on the Rate and Selectivity of Propylene Oxidation on Silver in a Solid Electrolyte Cell, J. Electrochem. Soc. 131(4), 839-845 (1984). 

T.M. Giir, and R.A. Huggins, Decomposition of Nitric Oxide on Zirconia in a Solid-state electrochemical cell, J. Electrochem. Soc. 126(6), 1067-1075 (1979). 

F. Grosz in Proc. 2nd Inti. Symp. on Solid Oxide Fuel Cells, (1991) Athens, Greece ... 

A.D. Frantzis, S. Bebelis, and C.G. Vayenas, Electrochemical promotion (NEMCA) of CH4 and C2H4 oxidation on Pd/YSZ and investigation of the origin of NEMCA via AC impedance spectroscopy, Solid State Ionics 136-137, 863 (2000). 

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