Stability of modified alumina with Fe_2O_3 at high temperatures

摘要

Transmission Mossbauer spectroscopy has been used to study the temperature effect on modified alumina with Fe_2O_3, used for the separation of hydrocarbons like alkanes and alkenes. The phases were determined qualitatively and quantitatively formed at each temperature ranging from 400 to 1200 1C. High spin Fe~(3+) is found to exist at each temperature with different concentrations in the form of FeAlO3 phase. The material is completely paramagnetic up to 400 1C, whereas it is partly paramagnetic at higher temperatures. Above 400 1C, different iron oxides are formed along with Fe~(3+). A small amount of g-Fe is also produced at 600 and 800 1C. Finally, maghemite (g-Fe2O3) and Fe~(3+) are detected at 1200 1C.