Trypolskyi A. Fractal structure of the catalyst surface and the kinetics of the heterogeneous-catalytic oxidation and reduction reactions of carbon oxides

It is investigated the relationship between a catalyst morphology and a rate constant of a rate-limiting stage of a reaction that occurs on the surface of a catalyst and a theoretical approach is proposed which explains the observed impact of the fractal structure of a catalyst on the activation energy and pre-exponential multiplier of the rate constant. It is proposed the mechanism of the carbon oxide hydrogenation to hydrocarbons and alcohols in the presence of supported bi-metallic rhodium-containing catalysts and it is established a relationship between the electron state of Rh and catalytic activity and selectivity of a rhodium-containing catalyst. The mechanism of the carbon dioxide hydrogenation to methane, its homologues and carbon monoxide is established and it is obtained full kinetic model of the process on supported transition metals. The peculiarities that relate hydrogen adsorption heat on a catalyst with its activity and selectivity in the reaction of carbon mono- and dioxide hydrogenation are investigated. It is shown that that the value of the hydrogen adsorption heat may be varied by changing the chemical nature of a metal as well as its dispersion, which depends on the modifying agents and preparation conditions. It is approved that increasing the surface roughness, which is accompanied by an increase of the fractal dimension, results in a decrease of the rate constant of a catalytic reaction. The highest activity is exhibited by a catalyst which is characterized by a regular structure and sharp size distribution of the particles of an active component.