Synthesis of Hydrated Alumina Gel by the Homogeneous Precipitation Method and lts Change by Heating

Abstract

Hydrated alumina gel was synthesized by using the homogeneous precipitation method by urea and aluminum salts, and the change of constitution due te the heating ef product and the influence ef anion in case of synthesizing hydrated alumina gel were investigated by continuous pH measurement, differential thermal analysis thermegravimetric analysis and powder X-ray diffractien analysis.
In case of synthesizing hydrated alumina gel, a superior filterable granulaf substance was obtained when aluminum sulfate was used, on the other hand when aluminum chloride and aluminum nitrate were used, an inferior filterable gelform substance was obtained, and the pH value of the precipitates obtained was about 4 in the granular substance and about 7 in the ge1 orm substance.
When these products were thermally treated, the granular subs ance ch ngedl int alumina at 900 C and to alumina at 1150 C, while the ge1-form substance changed into alumina at 700 C and into alumina at 1150C.
From thdse results it was ade clear that the hydrated alumina ge16ynthesi ed by Using the homogeneous precipitation method h4s dif erent preperties dependlng on the starting materlaL