Particulate titanium oxide, method and apparatus for manufacturing the same, and treatment methods using such titanium oxide

Abstract

Titanium oxide grains of large specific area and high crystallinity with reduced internal defects, whose high photocatalytic activity as a photocatalyst is promising; and titanium oxide grains which even when heated at high temperature, exhibits low tendency of transformation to rutile crystal structure and exhibits low rate of sintering. As titanium oxide grains for composing a photocatalyst, use is made of those of the shape of a boxy polyhedron. The polyhedron constituting the titanium oxide grains is composed of one or more titanium oxide single-crystal polyhedrons. The crystallinity can be enhanced by causing the flatness ratio of single-crystal polyhedrons to fall within the range of 0.33 to 3.0. It is preferred that the polyhedron be a hexa to decahedron. The rutile transformation ratio R (700 to 24) is to be 7.5% or less while the rutile transformation ratio R (500 to 24) is to be 2.0% or less. Titanium oxide grains of the above configuration are produced through a process comprising feeding titanium tetrachloride vapor and oxygen into a synthetic tube of quartz glass and heating them from the exterior of the synthetic tube by means of an oxyhydrogen flame burner so as to effect thermal oxidation.

Description

Background technique [0001] The present invention relates to titanium oxide particles used in photocatalysts and the like, a production method, a production device, and a treatment method thereof. By making titanium oxide particles into particles of a new shape, the photocatalytic activity of the photocatalyst can be greatly improved. [0002] Photocatalysts composed of titanium oxide particles are well known. The photocatalytic reaction of titanium oxide particles is a chemical reaction caused on the surface of titanium oxide particles, and the chemical substance to be decomposed begins its reaction by being adsorbed on the surface of titanium oxide particles. Therefore, the smaller the particle size of the titanium oxide particles, the higher the photocatalytic activity. [0003] In the prior inventions disclosed in Japanese Patent Laid-Open No. 11-267519, Japanese Patent Laid-Open No. 08-164334, and Japanese Patent Laid-Open No. 07-303835, it is desired to reduce the parti...

AI Technical Summary

Problems solved by technology

[0016] However, it is generally known that when titanium oxide particles with an anatase crystal structure are supported, as described above, when heated to about 500°C to 700°C, the crystal structure changes to the rutile type, and the photocatalytic activity decreases.

[0017] In addition, when the heating is performed, the titanium oxide particles are sintered with each other, and the surface area thereof is reduced, and due to this reason, the photocatalytic activity is also reduced.

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