Effects of alkali-metal ions on the thermal decomposition of ammonium metavanadate supported on alumina |
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Authors: | A A Said |
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Affiliation: | (1) Department of Chemistry, Faculty of Science, UAE University, PO Box 17551, Al-Ain, United Arab Emirates;(2) Present address: Department of Chemistry, Faculty of Science, Assuit University, Assuit, Egypt |
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Abstract: | The thermal decomposition of ammonium metavandate (AMV) supported on -alumina (1 1 mol) and treated with alkali-metal ions was investigated using differential thermal analysis (DTA), thermogravimetric analysis (TGA), infrared (i.r.) absorption spectroscopy and X-ray diffraction (XRD). The results revealed that the presence of alkali-metal ions did little to affect the thermal decomposition processes of AMV supported on alumina. However, these ions enhanced creation of V4+ ions by heating the samples in air at 400 °C. The oxides produced underwent a solid-solid interaction at 500–700 °C, forming alkali-metal vanadates. The formation of these spinels was found to be strongly dependent on the degree of diffusion and the concentration of the alkali-metal ions. Moreover, the addition of a higher concentration of alkali-metal ions inhibits the formation of aluminium vanadate while enhancing the crystallinity of - to -alumina. |
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