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Spectroscopic determination of the kinetic model and of activation energies of Co3O4 surface dissociation on γ-Al2O3 and SiO2 modified with alkaline earth cations

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Abstract

The kinetic model which follows the surface dissociation of Co3O4 on γ-Al2O3 and SiO2 modified with alkaline earth cations has been investigated using the Arrhenius kinetic law as an approximate criterion. It was found that on both classes of modified carriers a “phase boundary reaction control” mechanism fits the experimental points. Using this model, the activation energies were calculated. The modification of γ-Al2O3 brings about a decrease of Ea values whereas that of SiO2 causes an increase in activation energy. These effects, in conjunction with the “initial values” of the Co3O4 concentration, explain the influence of alkaline earth cations on the Co3O4/γ-Al2O3 and Co3O4/SiO2 catalytic systems and support the tentative mechanism proposed earlier.

Abstract

Кинетическая модель, заключающая в себе поверхностную диссоциацию Co3O4 на γ-Al2O3 и SiO2, модифицированных катионами щелочноземельных элемен-тов, была исследована, используя Аррениусовский закон как приблизительный критерий. Было найдено, что для обоих классов модифицированных носителей механизм “контроля реакций на границе раздела фаз” согласуется с экспери-ментальными данными. Используя эту модель, были рассчитаны энергии актива-ции. Модификация γ-Al2O3 приводит к уменьшению величины Ea, в то время как модификация SiO2 вызывает повышение энергии активации.

Эти эффекты, вместе с “исходными величинами” концентрации Co3O4, обья-сняют эффект катионов щелочноземельных элементов на каталитические сис-темы Co3O4/γ-Al2O3 и Co3O4/SiO2 и подтверждают механизм, предложенный ранее.

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Authors and Affiliations

  1. Physical Chemistry Laboratory, University of Patras, Patras, Greece

    A. Lycourghiotis, M. Kotinopoulos, A. Tsiatsios, N. Katsanos & G. Karaiskakis

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  1. A. Lycourghiotis
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  2. M. Kotinopoulos
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  3. A. Tsiatsios
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  4. N. Katsanos
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  5. G. Karaiskakis
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Lycourghiotis, A., Kotinopoulos, M., Tsiatsios, A. et al. Spectroscopic determination of the kinetic model and of activation energies of Co3O4 surface dissociation on γ-Al2O3 and SiO2 modified with alkaline earth cations. React Kinet Catal Lett 20, 163–169 (1982). https://doi.org/10.1007/BF02063603

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  • DOI: https://doi.org/10.1007/BF02063603

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