Decomposition of NO in the presence of oxygen was promoted by using an electrochemical cell composed of YSZ and non-porous Pd electrodes. The NO conversion into N2 was successfully improved by coating the Pd electrodes with a perovskite oxide (La1−xSrxCoO3).
Two kinds of alumina (A1203-l, A120,-2) have been examined for glucose adsorption from dimethyl sulphoxide solutions. The AI,O,-l adsorbent is found to adsorb considerable amounts of glucose while the AI , O, -2 adsorbent is found to adsorb little glucose.IR spectroscopy of the adsorbents and adsorbed CO, species has revealed that AI,O,-l carries significant amounts of basic OH groups on its surface whereas A120,-2 carries few basic sites. This indicates that Al,03-l provides acidic glucose molecules with good adsorption sites (basic), which results in a larger degree of adsorption.XP spectroscopy of the adsorbents with and without adsorbed glucose has revealed that only the C 1s spectra for the Al,O,-l-glucose system exhibit measurable changes upon glucose absorption. From the analysis of the C 1s difference spectra, the molecular structure of glucose is found to be almost unchanged by the interaction with the basic site. This suggests that the acidic C,-OH group located at the periphery of the glucose molecule is responsible for the adsorptive interaction with the basic site. This view has been supported by a small adsorption capacity of AI,O,-l for the methyl-a-o-glucoside adsorbate.
The mutarotation of α-d-glucose to β-d-glucose has been studied at 25±0.1 °C using five kinds of alumina as catalysts. Two kinds of alumina with measurable surface basicities have exhibited high catalytic activities while the others with little surface basicities have exhibited low activities. Thus, the surface basic sites have been considered to be responsible for the catalytic activity observed. Any of crystal structures, surface areas, pore structures, and surface elemental compositions have no relation to the catalytic activity. It has also been revealed that the kinetics of the reaction is explained by a surface reaction mechanism
α+1 \undersetKα\ightleftharpoons αad \oversetk1\undersetk2\ightleftharpoons βad \undersetKβ\ightleftharpoons β+1,
where 1, Kα, Kβ, k1 and k2 denote the active site, the adsorption equilibrium constant for α, the adsorption equilibrium constant for β, the rate constant for the surface forward reaction, and the rate constant for the surface backward reaction, respectively, and the subscript ad denotes an adsorbed state. The result of kinetic analysis has revealed that Kβ>Kα, indicating that the adsorption of β-glucose is stronger than that of α-glucose. This also supports the view that the surface basic sites are responsible for the catalytic activity.
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