Chemistry of inorganic compounds – Oxygen or compound thereof – Metal containing
Patent
1990-10-01
1993-04-06
Lewis, Michael
Chemistry of inorganic compounds
Oxygen or compound thereof
Metal containing
423608, C01G 23047
Patent
active
052001679
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to fine particle titanium oxide which is spherical and mono dispersed. The obtained titanium oxide is, for example, used as a material for fine ceramics and cosmetics.
DESCRIPTION OF RELATED ART
Conventional methods for the preparation of titanium oxide from titanium alkoxide include the gas phase pyrolysis method (e.g. Japan Kokai Tokkyo Koho 85186418) and the liquid phase hydrolysis method (e.g. U.S. Pat. No. 4,543,341, Japan Kokai Tokkyo Koho 87226814, and Japan Kokai Tokkyo Koho 87278125). The titanium oxide obtained by the gas phase pyrolysis method is generally amorphous and the particles are often agglomerated so that the agglomerated should be dispersed. With regard to the liquid phase method, such methods as to synthesize spherical titanium oxide of mono dispersion with less agglomerated powder have been proposed, though they have complicated processes and low productivity.
SUMMARY OF THE INVENTION
An organic titanium compound and an organic compound which can react with the said organic titanium compound are heated, the generated vapor of each compound is introduced by a carrier gas into a reaction zone to carry out a gas-phase reaction. Then, the obtained product is hydrolyzed with water, steam or others.
The titanium oxide thus obtained is not agglomerated and is fine particles of mono dispersion and real sphere.
The said organic titanium compound and the organic compound which can react with the organic titanium compound which are used are both a compound which is volatile and gives a solid product by gas-phase reaction of the two compounds.
Organic titanium compounds preferably used are titanium tetraalkoxides and/or their derivatives. The titanium tetraalkoxides include titanium tetraethoxide, titanium tetra-n-propoxide, titanium tetra-i-propoxide, titanium tetra-n-butoxide and titanium-tetra-t-butoxide. The derivatives include their oligomers such as dimers and trimers, and compounds substituted by such substituents as acyloxy group. A mixture of two or more compounds of these can be used.
Out of the above compounds, particularly preferable is at least one compound selected from the group consisting of titanium tetraethoxide, titanium tetrapropoxide and titanium tetra-n-butoxide.
Organic compounds which can react with organic titanium compounds include alcohols and phenols such as methanol, ethylene glycol, phenol and cresol. A mixture of two or more compounds of these can be used. Particularly preferable is methanol.
In the method of this invention, an organic titanium compound and an organic compound which can react with the organic titanium compound are usually heated to vaporize. Any methods for vaporizing them can be acceptable if vapor is generated efficiently. The vapors of organic titanium compound and organic compound which can react with the organic titanium compound are introduced into a reaction zone by using a carrier gas including inert gas such as nitrogen or helium, or air. A preferable reaction section is a tubular device. However any device is acceptable if the gas phase reaction of the two compounds proceeds quickly and efficiently.
A change in vapor concentration of the organic titanium compound in the reaction section can control the grain size. Usual reaction conditions are a holding time of 0.01 to 10 seconds, a flow rate of 0.1 to 10 m/sec, a concentration oforganic titanium compound of about 0.001 to about 1% by volume, and a reaction mole ratio of organic compound which can react with the organic titanium compound to the organic titanium compound is about 10 to about 40.
The product obtained in the reaction zone is collected by using a proper filter, and hydrolyzed with such as steam, water or aqueous ammonia. After the hydrolysis, the obtained titanium oxide is dried by a drying oven or others to give the final product.
According to the method of this invention, the titanium oxide particles can be controlled at will in the range of about 0.1 to about 10 .mu.m in diameter and about 1 to about 60 m.sup.2 /g (BET m
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Cotton et al, "Advanced Inorganic Chemistry", 4th ed., p. 1164.
Imagawa Tutomu
Maeda Umio
Noziri Masatugu
Lewis Michael
Mason, Jr. Joseph C.
Nguyen Ngoc-Yen M.
Nippon Soda Co. Ltd.
Smith Ronald E.
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