JPH0952714A - Method for fixing titanium dioxide and fixation product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance catalytic activity of the fixation product and to inhibit titanium dioxide from being released from the carrier by impregnating a porous carrier with at least one compound selected from an organotitanium compound group and thereafter, decomposing the organotitanium compound(s) to deposit the resulting titanium dioxide on the carrier and to fix it inside the carrier. SOLUTION: In this method, a chemically stable and porous carrier is impregnated with at least one compound selected from organotitanium compounds such as alkoxytitaniums, titanium acylate compounds and titanium chelate compounds, titanium halides, etc., wherein if necessary, the compound(s) may be diluted with a solvent or the like beforehand. Then, this compound(s) is subjected to hydrolysis and/or thermal decomposition to deposit titanium dioxide on the carrier and to fix it inside the carrier. The hydrolysis is performed by utilizing atmospheric temp., water, hot water, steam, or the like and optionally, further adding an acid or alkali to promote the hydrolysis. At this time, heating to <=200 deg.C is sufficient to perform this hydrolysis. Afler fixing titanium dioxide inside the carrier, if necessary, the resulting carrier is optionally washed and dried and/or subjected to high temp. treatment. Also, by using a silicon compound, fluororesin, or the like together with the above compound(s) and/or chemicals, the titanium dioxide fixation strength is further enhanced.

Description

Detailed Description of the Invention

[0001]

The present invention relates to water treatment, waste gas treatment,
The present invention relates to a method for immobilizing titanium dioxide having a catalytic action that can be effectively used in the production of chemicals and the immobilization product thereof.

[0002]

2. Description of the Related Art Titanium dioxide is expected to be used in a wide range of fields because it has an excellent catalytic action, but since it is a powder, it is difficult to handle and the fields in which it can be used are limited.

In recent years, the environmental compatibility of titanium dioxide has been evaluated, and it has been expected to be used particularly in the water treatment field. Therefore, immobilization of titanium dioxide has been attempted to overcome the difficulty in handling. The main known methods for immobilizing titanium dioxide to date are a method of applying tetraalkoxytitanium to a carrier and baking it, a method of fixing titanium dioxide powder to the carrier, and the like.

[0004]

Titanium dioxide shows a very strong catalytic activity when a powdery one is dispersed, but when it is fixed, the catalytic activity tends to be weakened.

The conventional methods have tried to enhance the catalytic activity of the immobilization product by enhancing the catalytic activity of titanium dioxide itself, but no satisfactory results have been obtained. Specifically, in the method of applying tetraalkoxy titanium, it is 4
Although the catalytic activity of titanium dioxide itself is strengthened by firing at a temperature of about 00 ° C, this method has a limit in the amount and surface area of titanium dioxide that can be fixed, and an immobilized product with strong catalytic activity cannot be obtained.

Further, in the method of fixing the titanium dioxide powder, titanium dioxide having high activity is selected and fixed, but the titanium dioxide powder is easily separated from the fixed substance. As described above, it has been difficult to obtain an immobilized product having both the catalytic activity of titanium dioxide and the fixing force by the conventional technique.

The present invention has been made in order to solve the above-mentioned problems, and an object thereof is to enhance the catalytic activity of a titanium dioxide immobilization product and to eliminate the exfoliation of titanium dioxide.

[0008]

The present invention has been made in order to solve the above technical problems, and enhances the catalytic activity of the immobilization product by making the surface area of the titanium dioxide film very large. Provided is a method for immobilizing titanium dioxide, which comprises fixing the titanium dioxide film by a method in which the titanium dioxide film does not peel off.

In the present invention, a compound capable of precipitating titanium dioxide, such as an organotitanium compound or titanium halide, is impregnated into the porous carrier in advance, and then titanium dioxide is precipitated so that fine particles inside the carrier can be obtained. A titanium dioxide film is formed in the holes.

Since titanium dioxide immobilized by the method of the present invention has a very large surface area, it is possible to obtain an immobilized product having excellent activity without high temperature treatment. Also, since titanium dioxide is mainly formed in the pores of the support,
An immobilization product with almost no exfoliation of titanium dioxide is obtained.

The carrier used in the present invention may be a chemically stable and porous material. A material that transmits ultraviolet rays is desirable, but a material that does not transmit ultraviolet rays can also be used. Specific examples include silica gel, ceramics, zeolite, and natural minerals. Further, these carriers may be attached to glass, metal, plastic, fiber woven fabric or the like.

Examples of compounds to be absorbed by the carrier include organic titanium compounds and titanium halides. Examples of the organic titanium compound include alkoxytitaniums, titanium acylate compounds, titanium chelate compounds and the like. More specifically, tetraisopropoxy titanium,
Tetra-n-butoxytitanium, tetraoctoxytitanium, titanium acetylacetonate, octylene glycol titanate, triethanolamine titanate and the like are preferably used. Examples of titanium halides include titanium chloride and titanium bromide. Two or more compounds to be absorbed by the carrier may be used, diluted with a solvent or the like, or other additives may be added.

Examples of the treatment for depositing and fixing titanium dioxide inside the support include treatments such as hydrolysis and / or thermal decomposition. When hydrolyzing, the treatment conditions may be set according to the ease of decomposition of the compound absorbed on the support, humidity in the air may be used, or immersion in water or hot water may be used. Well, steam may be used. Further, in order to accelerate the decomposition of the compound with which the carrier is impregnated, an acid, an alkali or the like may be used in combination. In the case of thermal decomposition, it was necessary to heat at around 400 ° C. in the conventional method, but according to the present invention, heating at 200 ° C. or lower is sufficient. When treating the carrier impregnated with the compound, two or more treatments may be combined. In addition, after fixing titanium dioxide, washing, drying and / or high temperature treatment may be carried out, if necessary.

According to the present invention, titanium dioxide adheres to the support more firmly than the prior art, but silicic acid compounds,
By additionally using a fluorine-based resin or the like, the fixing force of titanium dioxide can be further enhanced. Specifically, examples of the silicic acid compound include sodium silicate, potassium silicate, tetramethoxysilane, and tetraethoxysilane, and examples of the fluorine-based resin include polytetrafluoroethylene and tetrafluoroethylene hexafluoride. Examples of the resin include a propylene copolymer and the like. When a silicic acid compound or a fluororesin is used in combination, it may be mixed with the compound with which the support is impregnated, used together when treating the support, or applied to the support after titanium dioxide is deposited. Absent.

[0015]

The present invention makes it possible to produce an immobilization product of titanium dioxide having both catalytic activity and adhesion of titanium dioxide by forming a titanium dioxide film inside a porous carrier. Will contribute to the practical application of.

[0016]

The present invention will be described below in detail with reference to examples. In addition,
The immobilization rate of the immobilization product, the presence or absence of peeling of titanium dioxide, and the ammonia removal rate in the examples were determined by the following methods.

(Immobilization rate) The carrier before and after immobilization is 40
It was dried at 0 ° C. for 1 hour, the dry weight was obtained, and the immobilization rate was calculated by Equation 1.

(Equation 1)

(Presence or absence of peeling of titanium dioxide) 2 g of the titanium dioxide-immobilized product and 10 g of water were put into an L-shaped tube and shaken for 30 minutes with a shaker, and the presence or absence of cloudiness in water was visually observed.

(Ammonia Removal Rate) Titanium dioxide decomposes a low-concentration substance with high efficiency when irradiated with ultraviolet rays, and is therefore suitable for treating odors, chromaticity components and the like in an aqueous system. Here, the removal rate of ammonia, which is a typical pollutant of water pollution and is a malodorous component, was examined. Specifically, 10 g of the titanium dioxide-immobilized product was placed in 100 ml of a 30 mg / l ammonia aqueous solution, and the ammonia removal rate after 12 hours was compared between the one placed in the dark and the one irradiated with ultraviolet rays.

Example 1 A mixture of 40 parts by weight of hexane and 2 parts by weight of tetraisopropoxytitanium was impregnated with 70 parts by weight of Caractact Q-15 (Fuji Silysia) and then left at room temperature to remove hexane. It was volatilized and titanium dioxide was deposited to obtain a fixed product of titanium dioxide. This immobilization product had very little separation of titanium dioxide, so there was very little loss of raw material, and problems such as dust did not occur even without special equipment. Since this immobilization product has water resistance, it can be used in both the gas phase and the liquid phase. Table 1 shows the immobilization rate of this immobilization product, the presence or absence of peeling of titanium dioxide, and the ammonia removal rate.

[Table 1]

<Example 2> 40 parts by weight of n-butanol and 2 parts by weight of tetraisopropoxy titanium were mixed and impregnated with 70 parts by weight of silica gel B (Toyoda Kako).
Hexane was volatilized by heating at 0 ° C. and titanium dioxide was precipitated at the same time to obtain a titanium dioxide immobilization product. 10 g of the immobilization product obtained by this method was placed in 2 l of air containing 30 ppm of acetaldehyde, and the case where it was placed in the dark and the case where it was irradiated with ultraviolet rays were compared. When placed in the dark,
While the acetaldehyde concentration after 1 hour was 3 ppm, acetaldehyde was not detected in about 20 minutes when irradiated with ultraviolet rays.

Example 3 67 parts by weight of ethanol and 3 parts by weight of diluted titanium tetrachloride were mixed and impregnated with 70 parts by weight of zeolite. This is left indoors to evaporate ethanol, then immersed in water for 30 minutes, washed with water, and 180 °
Dried at C for 3 hours. When this immobilization product was used in place of the paving stones of ornamental fish, water stains were greatly improved.

Example 4 30 parts by weight of hexane and tetra-n- were added to a glass plate on the surface of which zeolite powder was attached.
100 g / m ^{2 of} a liquid obtained by mixing 3 parts by weight of butoxy titanium
The coating was applied to about 10 minutes, dried in air, and washed with water. This immobilized product was used in Example 2.
When evaluated in the same manner as in (1), this immobilizate showed good acetaldehyde decomposability.

Comparative Example 1 A carrier mixture of 3 parts by weight of titanium dioxide / nitric acid dispersion liquid (containing 30% of titanium dioxide) and 3 parts by weight of water was Caractact Q-15 (Fuji Silysia) 70.
After spraying on parts by weight, it is dried at 105 ° C and 40
The mixture was baked at 0 ° C to obtain a titanium dioxide immobilization product. This method produces titanium dioxide powder as a by-product,
There were problems such as material loss and dust. In addition, nitric acid volatilizes during drying and baking, which may adversely affect the human body, devices and the like. The immobilization rate, the presence / absence of peeling of titanium dioxide, and the ammonia removal rate of this immobilization product were determined in the same manner as in Examples, and the results are shown in Table 1.

[Table 1]

Comparative Example 2 In the same manner as in Example 1, the presence or absence of exfoliation of titanium dioxide and the ammonia removal rate were determined in the same manner as in Example 1 using a commercially available titanium dioxide immobilization product in which titanium dioxide powder was fixed to glass beads with a fluororesin. Shown in 1.

[Table 1]

Claims (3)

[Claims] 1. A method of impregnating a porous carrier with one or more compounds selected from the group of organic titanium compounds, followed by decomposition to deposit titanium dioxide, and fixing the titanium dioxide inside the carrier. A characteristic method for immobilizing titanium dioxide and its immobilization product. 2. A method of impregnating a porous carrier with one or more compounds selected from the titanium halide group and then decomposing it to precipitate titanium dioxide and fixing it inside the carrier. A characteristic method for immobilizing titanium dioxide and its immobilization product. 3. A combined use of one or more compounds selected from the group of silicic acid compounds and the group of fluororesins.
The method for immobilizing titanium dioxide according to 2 and 3, and its immobilization product.