JPS5950003A - Manufacture of fine metallic oxide - Google Patents

Abstract

PURPOSE:To prevent the clogging of a burner and to manufacture a fine metallic oxide of a uniform grain size by feeding a volatile metallic halide from nozzles in the wall of a reaction chamber to a flame generated from a burner placed at the central part of the chamber to cause a combustion hydrolysis reaction. CONSTITUTION:A combustible gas is fed to a vertically movable burner 2 for combustion placed at the central part of a reaction chamber 1. Oxygen or a gas contg. oxygen is fed from an inlet 4 formed in the wall of the chamber 1, it is passed through a wire net 5 to regulate the flow, and the inside of the chamber 1 is kept at 600-1,500 deg.C by burning the combustible gas. A volatile metallic halide such as silicon tetrachloride is introduced into the chamber 1 from the nozzles 3' of inlets 3 in the wall of the chamber 1 to cause a combustion hydrolysis reaction. The resulting fine metallic oxide is recovered.

Description

[Detailed description of the invention] The X invention performs volatile metal halide basin combustion hydrolysis,
It relates to a method for producing corresponding fine metal oxides. Specifically, the present invention provides a method for producing fine metal oxides in a manner that prevents clogging of combustion burners when volatile metal halides are subjected to combustion hydrolysis.

Conventionally, various methods have been known for producing fine metal oxides such as silicon dioxide and titanium dioxide by combustion hydrolysis of volatile metal halides such as silicon tetrachloride and titanium tetrachloride. .

For example, Tokkosho: 16-33. ! ;9. 117-l
IA 2? Publication No. U discloses a method for producing fine metal oxides by carrying out a combustion hydrolysis reaction by continuously supplying a volatile metal halide together with a flammable gas and an oxygen-containing gas through a burner. has been done.

However, volatile metal halides like this? When a combustible gas (especially hydrogen or a hydrogen-containing gas) and an oxygen-containing gas are premixed and subjected to a combustion hydrolysis reaction, adhesion of metal oxides generated at the nozzle end of a burner for skeletal combustion hydrolysis. However, deposits are unavoidable, and continuous operation causes the burner nozzle to become clogged.

Therefore, in the above patent publication, the gas outflow velocity at the combustion burner outlet is increased by
A method for preventing the adhesion and formation of metal oxides in the burner nozzle has been suggested.

On the other hand, in Japanese Patent Publications No. 31-6307 and No. 3/-630g, a volatile metal halide is supplied to a reaction chamber separately (without premixing) with a flammable gas, and the combustion flame of the flammable gas is A method is disclosed for producing fine metal oxides by contact combustion hydrolysis, completely avoiding blockage of combustion burner nozzles. However, in the multi-tube/9-ner which is described as the main aspect of the burner for combustion hydrolysis in the above patent publication, the inlets for the volatile metal halide and the combustible gas are very close to each other. Blockage of the burner nozzle cannot be sufficiently avoided. Furthermore, in the conventional method of feeding volatile metal halides and combustible gases into the reaction chamber separately (without premixing), fine metal oxides are produced even if blockage of the combustion burner nozzle is avoided. The disadvantage is that the particle size is non-uniform.

Therefore, the object of the present invention is to provide a method for producing fine metal oxides by combustion hydrolysis of volatile metal halides, which avoids clogging of the combustion burner and produces fine metal oxides with uniform particle size. There are a whole range of manufacturing methods available. That is, the present invention involves burning and hydrolyzing volatile metal halides in a reaction chamber having a flammable gas combustion burner in the center and an inlet for the volatile metal halide in the peripheral wall. This is a method for producing fine gold) 14 oxide with all the characteristics.

The method of the present invention belongs to the mode in which the volatile metal halide and the combustible gas are supplied separately (premixed) to the reaction chamber and combusted and hydrolyzed 1q4. Unlike a burner, the combustion burner nozzle of the combustible gas separates from the inlet of the volatile metal halide in the reaction chamber, so the group closure by the noble oxide produced by the burner nozzle is substantially reduced. be avoided.

In addition, in the present invention, in order to uniformly supply the volatile metal halide from the peripheral wall of the reaction chamber to the flame from the combustion burner and hydrolyze the fuel, fine metal oxides with uniform particle size are used. You can get it. In order to uniformly supply such a volatile metal halide to the entire combustion flame, this can be achieved by providing at least one inlet or uniform slits at equal intervals on the peripheral wall of the reaction chamber.

Conventional conditions that generally affect the particle size of the metal oxide produced in the combustion hydrolysis reaction of volatile metal halides include reaction temperature, gas concentration and flow rate of the volatile metal halide introduced, and the particle size of the metal oxide produced. The degree of rupture, length of stay, etc. are controversial. In order to obtain the desired fine metal oxide, the above reaction conditions VC'A are set in advance in the present invention. How they are introduced and brought into contact is extremely important. That is, in the present invention, a good fine metal oxide can be easily obtained by selecting the optimal point for introduction and contact of volatile metal halides with respect to a predetermined combustion flame.

Introduced to the combustion flame of such volatile metal halide
The position of the mackerel to be contacted cannot be absolutely determined, but it may be determined appropriately depending on the condition of the combustion flame, especially below the combustion burner. In general, the volatile metal halide inlet t
・In the reaction chamber provided on the peripheral wall, a simple method is to move the combustible gas combustion burner provided in the center up and down. Therefore, it is recommended to use a flammable gas combustion burner in the center of the reaction chamber that can be moved up and down.

The volatile metal halide used in the present invention is not particularly limited as long as it undergoes a combustion hydrolysis reaction to produce the corresponding metal oxide. ψ (1) is a halide such as silica, titanium, aluminum, etc., and silicon halides such as silicon tetrachloride, silica tetrachloride, trichlorosilane, methyltrichlorosilane, dichlorosilane, trimethyldichlorosilane, or Titanium tetrachloride, aluminum chloride, etc. are useful.Such volatile metal halides may be introduced alone in gaseous form or supported in air, inert gas, etc.

Further, as the combustible gas, hydrogen or a hydrogen-containing gas which is combusted to produce hydrogen, or natural gas, coal gas, or petroleum-N gas is used. Such a flammable gas may be introduced into a combustion burner alone and burned in an oxygen atmosphere, or may be introduced together with a flammable gas and oxygen or an oxygen-containing gas and burned. The amount of flammable gas introduced is sufficient to burn and maintain the reaction temperature (flame temperature), which is generally 60θ to 1500℃, and the generated water is sufficient to at least hydrolyze the volatile metal halide introduced separately. Quantity is required. Therefore, the amount of oxygen or oxygen-containing gas introduced must be at least a theoretical amount sufficient to burn out the flammable gas and generate water.

Generally, the amounts of flammable gas and oxygen (or oxygen-containing gas) introduced are slightly in excess of the above-mentioned theoretical amounts. In addition, if the water generated by combustion of the flammable gas is insufficient for the hydrolysis reaction of the volatile metal halide, water or steam may be separately introduced.

In addition, the method of the present invention can be carried out in accordance with the known method of producing fine metal oxides by combustion hydrolysis of volatile metal halides.

That is, the reaction gas containing the generated metal oxide is quickly removed from the old system, and after cooling and coagulation steps, the metal oxide is completely separated.

Hereinafter, regarding the present invention, the 79i! One figure is shown and explained in the drawing. FIG. 1 is a longitudinal cross-sectional view of the reactor, with a burner 2 for combustion of flammable gas in the center of the reaction chamber l, an inlet 8 for volatile metal halide, and an oxygen (or oxygen-containing gas) inlet 8 in the inner peripheral wall. Introduction port 4? ! There are 7 arranged. Combustion burner 2 contains combustible gas, or combustible gas and oxygen (
or oxygen-containing gas) is completely introduced and combusts, creating a flame sound. It is also possible to introduce oxygen or acid-containing gas through the inlet 4 and burn it in the combustible gas combustion burner 2 in an oxygen atmosphere rectified by, for example, a wire mesh 5. The tip nozzle of the combustion burner 2 is arranged as shown in the cross-sectional view of Fig. 2, and nine nozzle holes 2' are provided at equal intervals to maintain a stable combustion flame of flammable gas. did. In general, the shape of the tip nozzle of the combustion burner is not particularly restricted; for example, a straight nozzle burner is also recommended.

On the other hand, the introduction port 8 for the volatile metal halide is arranged as shown in FIG. The metal oxide could be uniformly introduced and brought into contact with the combustion flame. In addition, volatile metal halide inlet 8
As shown in FIG. 1, it is preferable to provide the inlet so as to be shielded from the combustion burner in the downward direction so as to avoid any direct contact with the combustion flame, in order to prevent clogging of the inlet.

Next, examples will be shown, but the present invention is not limited to the following examples.

Example 1 In a reactor having the structure shown in Fig. 1, the maximum diameter/20 m
The burner 2 is installed in a cylindrical reaction chamber that can be moved up and down, and the gaseous silicon tetrachloride inlet 8 is installed at an angle of qS with respect to the horizontal to stabilize the oxygen or oxygen-containing gas in the inlet 4. A wire mesh with NO mesh was provided to maintain uniformity. In addition, the total inner diameter of the introduction holes (q) at the tip of the nozzle of the burner 2 is S■, and the inner diameter of the tip holes (q) at the gaseous silicon tetrachloride introduction port 8 is 2vu.
ns Inner diameter of oxygen or oxygen-containing gas inlet 4? 11-
/, 2 fins.

Using the above reactor, hydrogen gas was supplied as a combustible gas to the burner 2 at a rate of 10 m3/hr% and air was supplied from the inlet 4 at a rate of k33 m'/hr, and ignited to form a full combustion flame. On the other hand, gaseous silicon tetrachloride was supplied from the inlet 8 at a rate of f Q m3/hr to bring it into contact with the flame. In this case, while measuring the temperature of the flame,
The position of the burner 2 was moved up and down at regular intervals, and each time all of the produced silica powder was recovered and its physical properties were observed. When silica powder exhibiting desired physical properties was thus obtained, the burner 20 position was determined.

Next, as a result of continuous operation for 20 hours under the above predetermined conditions, almost no deposits were left on the burner 2.
Furthermore, there was no risk of burner blockage even during full operation. The collected silica powder was a uniform transparent powder with a BET surface diameter of 10 m2/3 mμ (observed using an electron microscope with IQ magnification of 10,000 times).

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view for explaining the reaction apparatus in the present invention, and FIG. 2 is a cross-sectional view showing the position of the gas inlet in the reaction apparatus. 1 is the main body of the service room, 2 is a combustion burner for combustible gas, 2' is its nozzle hole, 8 is the introduction port for volatile metal halide, 8' is the nozzle hole, 4 is the introduction of oxygen or oxygen-containing gas Hole 5 is a wire mesh. Patent applicant: Tokuyama 1 Shun Co., Ltd. Fuki 1 Figure 2 Menini\ 14

Claims (1)

[Scope of Claims] 01 Volatile metal halides are uniformly supplied from the peripheral wall of the reaction chamber to the flame from a combustible gas combustion burner provided in the center of the reaction chamber, and fine particles undergo a combustion hydrolysis reaction. Method for producing metal oxides. (21) The method according to claim 11, wherein the volatile metal halide is a titanium or silicon halide. (3) The volatile metal halide is titanium tetrachloride or silicon tetrachloride. The method according to claim 21. (4) The method according to claim 1, wherein the combustion burner is vertically movable. (5) The volatile metal halide inlet or the combustion burner nozzle The method according to claim No. +It, wherein the method is arranged so as to be shielded from T1 from T1.