Preparation and Physicochemical Characterization of Cadmium and Zinc Ferrocyanides as Catalysts and Ion Exchangers

CADMIUM and zinc ferrocyanide complexes were prepared then ……calcined at 100, 400, 600 and 800 °C. The obtained solids were characterized using IR, XRD, N₂-adsorption measurements, H₂O₂ decomposition, and isopropanol conversion. The results showed that the diffractograms of ZnFeCN calcined at 600 -800°C consisted of  ZnO, K₂FeO₄, ZnFe₂O₄, K₂O-Fe₂O₃ phases while the CdFCN complexes calcined at 600-800°C composed of K₂CdO₂, K₂Cd₂O₃,  K₂FeO₄, K₂O-Fe₂O₃ phases and Fe₂O₃ (Maghemite phase). The S_BET of CdFeCN and ZnFeCN compounds were small and decrease with increasing the calcination temperature. CdFeCN and ZnFeCN are ion exchangers for ¹³⁷Cs⁺-removal. The exchange of ion capacity remained almost unaffected by changing the concentration of HNO₃ within 0.05-0.5M. The increase in the acid concentration above this limit brought about a significant decrease in the exchange of ion capacity. The decrease was however more pronounced in case of ZnFeCN complex. The catalytic activity of cadmium and zinc ferrocyanide complexes heated at100°C and 600 °C towards H₂O₂ decomposition was very small, while the complexes calcined at 800°C °C behaved as active catalysts. The catalytic activity of cadmium and zinc ferrocyanide complexes was moderate towards alcohol conversion and increased by increasing the calcination temperature. The increase was however much more pronounced in case of CdFeCN which shows better activity than ZnFeCN. CdFeCN and ZnFeCN acted mainly as dehydrogenation catalysts (above 90%).