The effect of the surface hydroxyls on the chlorination kinetics of alumina

The chlorination kinetics of alumina samples containing various amounts of surface hydroxyls were studied by thermogravimetry. The phase composition and the specific surface area of the reacting solids were characterized by X-ray diffraction (XRD), IR and BET methods. At temperatures where the react...

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Bibliographic Details
Published in:Thermochimica acta 1989-09, Vol.149, p.205-213
Main Authors: Pap, I.S., Mink, G., Bertóti, I., Zelei, B., Székely, T., Hauthal, T., Blumenthal, G., Kranz, G.
Format: Article
Language:English
Subjects:
Chemistry
Exact sciences and technology
Inorganic chemistry and origins of life
Kinetics and mechanism of reactions
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Summary:The chlorination kinetics of alumina samples containing various amounts of surface hydroxyls were studied by thermogravimetry. The phase composition and the specific surface area of the reacting solids were characterized by X-ray diffraction (XRD), IR and BET methods. At temperatures where the reaction rate was controlled by the chemical process the highest initial reaction rates were observed on the partially dehydroxylated samples prepared from gibbsite at 670 K. The high reactivity towards phosgene was attributed to the special role of the surface hydroxyls in the chlorination process. At high conversions, however, a significant decrease in the reaction rate was observed; this can be explained by the consumption of amorphous and transition alumina phases which leaves behind less reactive boehmite of much lower specific surface area.
ISSN:0040-6031
1872-762X
DOI:10.1016/0040-6031(89)85282-7