JOURNAL of the Tunisian Chemical Society

serving the Research, the Education and the Industry

Effect of addition of Cr3+ and Eu3+ ions on the reductibility of Ni2+ in X zelithes and on the properties of metallic phase

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The presence of promoter ions in the Ni2+ /zeolithe X system has a great influence on nickel reductibility and formed metallic phases. The addition of Eu3+ ions allowed, after reduction of Ni2+, to the formation of a highly dispersed metallic state of nickel (d ≤ 12 Å). A similar dispersion can be obtained by using Cr3+ but with particle size superior to 20 Å. A comparative study of the reactivity of Ni°-Eu-zeolithe X and Ni°-Cr-zeolithe X systems showed a particular behaviour of nickel particles with diameter equal to or less than 12 Å. The chemisorption and catalytic properties of these particles are attenuated due to the formation of "hydrogen species" strongly chemisorbed on the nickel surface. These species inhibit the contact between sites and molecules to adsorb.

S. Djemel, A. Ghorbel

Pages 385-397

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