Processes for producing anatase titanium oxide and titanium oxide coating material

Abstract

Production processes are provided which can produce, at a relatively low temperature and in a reduced number of steps, anatase titanium oxide powder having high photocatalytic activity and large specific surface area and anatase titanium oxide slurry having high storage stability and dispersibility. The slurry thus obtained can also be coated, as a coating material having photocatalytic activity, on materials having low heat resistance. In the production process of anatase titanium oxide powder according to the present invention, a titania sol solution, a titania gel, or a titania sol-gel mixture is heat treated in a closed vessel under pressure, and the treated product is then dried to produce anatase titanium oxide powder. In the production process of anatase titanium oxide slurry according to the present invention, a titania sol solution, a titania gel, or a titania sol-gel mixture is heat treated in a closed vessel under pressure, and the treated product is then dispersed/stirred to produce anatase titanium oxide slurry.

Description

TECHNICAL FIELD The present invention relates to a process for producing anatase titanium oxide particularly having high photocatalytic activity as one of photocatalysts used, for example, as environment cleaning materials, for example, for the removal of harmful materials, the deodorisation / decomposition of offensive odor substances, antifouling, and sterilization, and more particularly to a process for producing anatase titanium oxide powder having high photocatalytic activity and large specific surface area, and a process for producing anatase titanium oxide slurry, containing the anatase titanium oxide powder, with excellent stability and dispersibility. The present invention also relates to a process for producing a coating material of titanium oxide as one of photocatalysts used, for example, as environment cleaning materials, for example, for the removal of harmful materials, the deodorisation / decomposition of offensive odor substances, antifouling, and sterilization. More ...

AI Technical Summary

Benefits of technology

An object of the first invention is to provide a process for producing anatase titanium oxide powder wherein a titania sol, a titania gel, or a titania sol-gel mixture is heat treated in a closed vessel to hybridize the effect of pr

Problems solved by technology

In the production of anatase titanium oxide powder by the gas phase process, all the above production processes have drawbacks such as the necessity of using a special apparatus in the production of anatase titanium oxide due to the adoption of high-temperature reaction atmosphere (generally 800° C. or above in the case of the gas phase process) and the use of highly reactive titanium chloride as a starting material.

In this process, however, a special apparatus should be disadvantageously used for the preparation of anatase titanium oxide.

The production of anatase titanium oxide powder by the sulfuric acid process is disadvantageous in that the number of steps is large and, for example, the operation is very complicate.

Due to this high temperature, the coating material cannot be coated on base materials having low heat resistance.

Therefore, usable base materials are limited.

In the preparation of the coating material, dispersing powdery anatase titanium oxide in a solvent causes the coagulation of titanium oxide particles which makes it impossible to maintain the activity of the particulate photocatalyst.

Further, in the form of the coating material, for example, the dispersion of anatase titanium oxide in the solution is heterogeneous, and, with the elapse of the time, titanium oxide particles disadvantageously settle at the bottom of the solution.

That is, the coating material ha

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