![]() ![]() Il est donc possible d’étudier l’activité catalytique des deux phases de silicate contenant des cations Co 2+ dans des environnements de coordination différents : tétraédrique et octaédrique. Sur la base d’analyse de données de spectroscopie photoélectronique des rayons-X (SPX), il est possible de conclure que, dans les silicates étudiés, il existe des cations Co 2+. ![]() Les synthèses des phases ont été confirmées par des données de diffraction des rayons-X (DRX), d’infrarouge à transformée de Fourier (IR-TF) et résonance paramagnétique électronique (RPE). Le Ca 2CoSi 2O 7 a été préparé par une synthèse en phase solide alors que le CaCoSi 2O 6 a été obtenu par méthode sol–gel. Dans la structure åkermanite du Ca 2CoSi 2O 7, les cations du cobalt occupent des positions de coordination tétraédrique par rapport aux atomes d’oxygène. Les phases cristallines appartiennent à deux types principaux de structures de silicate. On a réalisé la synthèse de deux silicates de calcium et de cobalt dans lesquels l’atome de cobalt occupe des positions diverses dans la structure. Then, it turns out that catalytically active complexes with Со 2+ ions in tetrahedral coordination are more efficient than those with such ions in octahedral coordination when equal concentrations of cobalt were used on the surface of the catalysts. Co-pyroxene exhibits higher catalytic activity than Co-åkermanite, but the higher cobalt content on the surface of Co-pyroxene should also be taken into account. It was found that cobalt silicates with crystal structures corresponding to pyroxene and åkermanite possess catalytic activity in the reactions of complete oxidation of CO and toluene. Thus, it is possible to study the catalytic activity of two silicate phases containing Co 2+ cations in different coordinations: tetrahedral and octahedral. On the basis of the XPS analysis, it can be concluded that Co 2+ cations exist in the studied silicates. The synthesis of the phases was confirmed by XRD, FTIR, and EPR data. Ca 2CoSi 2O 7 was prepared by solid-phase synthesis and CaCoSi 2O 6 was prepared by sol–gel method. In the Co-pyroxene structure of CaCoSi 2O 6, cobalt displays octahedral coordination. In the Co-åkermanite structure (Ca 2CoSi 2O 7), cobalt cations take tetrahedral coordination toward oxygen atoms. The crystal phases belong to two main structural silicate types. Two calcium–cobalt silicates were synthesized in which cobalt occupies different structural positions. ![]()
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January 2023
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