Influence
of aluminium precursor on physico-chemical properties of aluminium hydroxides
and oxides |
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Authors: | Barbara Pacewska Olga Kluk-Płoskońska D Szychowski |
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Institution: | (1) Warsaw University of Technology, Faculty of Building Engineering, Mechanics and Petrochemistry, Instytute of Chemistry, Płock, Poland, 09-400, Łukasiewicza 17 St. |
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Abstract: | An attempt
to obtain aluminium hydroxide that could give aluminium oxides of increased
thermal stability was made. Aluminium hydroxide was precipitated during a
hydrolysis of aluminium chloride in ammonia medium. The influence of preparative
conditions, such as a dosing rate of aluminium precursor, pH, duration of
the precipitate refluxing and temperature of calcination, on the properties
of obtained hydroxides and oxides was investigated. The materials were studied
with the following methods: thermal analysis, IR spectroscopy, low-temperature
nitrogen adsorption and adsorption–desorption of benzene vapours.
Precipitated boehmites had high values of S
BET
determined from nitrogen adsorption (220–300 m2g–1),
good sorption capacity for benzene vapours, developed mesoporous structure
and hydrophilic character. It has been proved that a high pH value during
the precipitation of aluminium hydroxide favoured better crystallisation of
boehmite structure, higher temperature of its dehydroxylation into γ-Al2O3,
and delayed transformation of γ phase into α-Al2O3.
Aluminium oxides derived from the hydroxides precipitated at a high pH were
the most stable at high temperatures, and were characterised with the best
surface properties.
The online version of the original
article can be found
at |
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Keywords: | boehmite metastable aluminium oxides thermal decomposition |
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