4 research outputs found

    Aggregation Features of Monodisperse Palladium Nanoparticles Supported on g-Al2O3

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    The production of supported on Ξ³-A1&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; palladium catalysts by colloidal solution deposition method have been improved. Influence of temperature on the structure and dispersion characteristics of supported nanosized palladium particles during catalyst preparation and activation was investigated. It has been shown that at temperatures below 300&lt;sup&gt;o&lt;/sup&gt;C monodisperse particles palladium catalysts are stable. Further temperature increase leads to aggregation of monodisperse metal nanoparticles by the mechanism of reaction-limited aggregation (RLA) to form polydisperse system.Key words: palladium nanoparticles, catalyst preparation, aggregation, catalyst thermal stability.</p

    The Kinetic Parameters of the Smoke Gases Purification Process From Carbon Monoxide on A Zeolite-based Manganese Oxide Catalyst

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    A modified MnO2 clinoptillolite was obtained by using the available zeolite rock from the Sokyrnytsia deposit (Khust district of the Zakarpattia region, Ukraine) using a simple technique of mixing solutions containing separately Mn2+ and MnO4-. It was determined that the total manganese content in the air-dry modified thermally untreated clinoptyllolite was 11.42 mg/g, which is 1.8 % in terms of MnO2.Structural characteristics, namely, the pore size distribution and specific surface area as the main basic characteristics of the catalyst, were studied, which were obtained from the isotherms of low-temperature nitrogen adsorption-desorption. These studies are necessary to determine the limiting stage of CO oxidation.It has been determined that the kinetics of the oxidation process is described by a first-order equation. Based on the obtained characteristics of the catalyst, the kinetic parameters of the process were calculated, namely, the effective and true rate constants and the activation energy, which is 31 kJ/mol. It has been proved that the oxidation reaction of carbon monoxide on an oxide-manganese catalyst proceeds in the intra-diffusion mode. This makes it possible, using the criterion dependences, namely, the Carberry criterion, which is less than 0.05, to assert that the reaction is not limited by the diffusion of CO from the gas stream to the outer surface of the catalyst. It is shown that the transport of carbon monoxide molecules inside the catalyst granules proceeds in the Knudsen regime.The obtained scientific result in the form of a kinetic description of the catalytic oxidation of carbon monoxide with atmospheric oxygen on a manganese oxide catalyst based on zeolite is interesting from a theoretical point of view. From a practical point of view, the calculated kinetic parameters of this process make it possible to calculate a catalytic CO oxidation reacto
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