EFFECTS OF SODIUM-HYDROXIDE TREATMENT ON COORDINATION CHANGES OF COBALT IONS IN CONAY BY MEANS OF UV-VIS DIFFUSE-REFLECTANCE SPECTROSCOPY

The coordination changes of Co2+ in CoNaY/NaOHs, prepared by cobalt io n-exchange and treatment with NaOH, during dehydration at various temp eratures have been investigated by UV/VIS diffuse reflectance spectros copy. After dehydration of CoNaY/NaOHs at 473 K, the DRS bands show th e formation of mixed cobalt oxide species interacted with lattice oxyg en. This mixed cobalt oxide species interacted with lattice oxygen dec ompose during further dehydration at 673 K The strong intensities of t he bands at 660, 575 and 530 nm after dehydration of CoNaY/NaOHs at 87 3 K indicate that a considerable amount of the cobalt ions remains in the sodalite cage with tetrahedral coordination even after dehydration at 873 K.