TW201641416A - Method of manufacturing metallic oxide particles - Google Patents

Abstract

A method of manufacturing metallic oxide particles of the present application includes steps in which a first merging gas is formed by merging a preheated metallic chloride-free first gas with a preheated metallic chloride containing gas at a first merging point, and a second merging gas is formed by merging a preheated metallic chloride-free second gas with the first merging gas at a second merging point separated from the first merging point toward a downstream side and is characterized in that neither metallic chloride containing gas nor the first gas contain oxygen or water vapor; the second gas contains at least oxygen; the first gas is heated so as to be the preheated temperature of the metallic chloride containing gas or more, is merged with the preheated metallic chloride containing gas, and thereby heats the preheated metallic chloride containing gas; and the second gas is heated so as to be the temperature of the first merging gas or more, is merged with the first merging gas, and thereby heats the first merging gas at the downstream side of the second merging point.

Description

Method for producing metal oxide particles

The present invention relates to a method for producing metal oxide particles, and particularly to a method for producing metal oxide particles of metal oxide particles for a long period of time without blocking the state of the material gas flow path.

The present invention claims priority based on Japanese Patent Application No. 2015-005149, filed on Jan.

In recent years, titanium oxide particles have attracted attention in the field of photocatalysts. For example, Patent Documents 1 and 2 and Non-Patent Documents 1 to 3 disclose a titanium oxide particle having a box-shaped shape of a decahedron and mainly composed of anatase crystal (hereinafter, also referred to as "decahedral titanium oxide". particle").

In Patent Documents 1 and 2 and Non-Patent Documents 1 and 3, the decahedral titanium oxide particles have a large surface area per unit mass, high crystallinity, and low internal defects, so that they have high activity as a photocatalyst. Further, Non-Patent Document 2 also discloses that the decahedral titanium oxide particles are expected to be a photocatalyst because of the high ratio of the (001) surface having high reactivity.

a method for producing decahedral titanium oxide particles, for example, non-specialized A method for hydrothermal reaction using hydrofluoric acid described in Document 2. However, since hydrofluoric acid has a strong acidity and is difficult to use, the production method of Non-Patent Document 2 using this material is not suitable for industrial use.

The method for producing decahedral titanium oxide particles described in Patent Documents 1 and 2 and Non-Patent Documents 1 and 3 is a reaction in which titanium tetrachloride (TiCl ₄ ) vapor and oxygen (O ₂ ) gas are introduced into a reaction tube. A method of producing titanium oxide particles (TiO ₂ ) by the reaction of the following reaction formula (1) by heating these gases outside the tube.

TiCl ₄ +O ₂ →TiO ₂ +2Cl ₂ ...(1)

By using the above production method, a powder product containing titanium oxide particles can be obtained on the downstream side of the reaction tube. This powdery product contains many decahedral titanium oxide particles.

In the above-described production method described in Patent Documents 1 and 2 and Non-Patent Documents 1 and 3, when the raw material gas is rapidly heated to a temperature at which titanium tetrachloride is subjected to thermal oxidation reaction, titanium tetrachloride which is a raw material is reacted with oxygen. The way the tube is heated externally. Therefore, when the flow rate of the raw material gas containing titanium tetrachloride and an oxidizing gas is large, the heat source outside the reaction tube does not ensure the thermal oxidation reaction of titanium tetrachloride in the raw material gas with the raw material gas in the reaction tube. The heat conduction required is completely consumed, so that the reaction cannot be completed, and as a result of remaining unreacted titanium tetrachloride on the downstream side of the reaction zone, there is a problem that the yield of the obtained powder product is lowered.

Further, in the production method described in Patent Document 3, the titanium tetrachloride which is a raw material and the first gas and the second gas which have been preheated are combined and heated in two stages, and the flow rate of the material gas is large. situation In the form of a titanium oxide particle having high photocatalytic activity, it is also possible to produce a high yield.

However, in the production method described in Patent Document 3, since at least one of the titanium tetrachloride-containing gas and the preheated first gas contains oxygen after the preheating, the quartz glass containing the titanium tetrachloride gas is introduced. The front end, the inner surface, the outer surface of the first hollow inner cylinder, and the front end and the inner surface of the second hollow inner cylinder made of quartz glass into which the first gas is introduced do not adhere to the adhesion of the titanium oxide or the film-like product in the initial stage. When the titanium oxide particles are to be produced for a long period of time, the deposits are gradually accumulated, and finally the raw material gas flow path is blocked, causing a problem that the first hollow inner cylinder or the second hollow inner cylinder is broken.

Adhesives, film-like products, and deposits accumulated in the front end, the inner surface, the outer surface of the first hollow inner cylinder, and the second hollow inner cylinder of the quartz glass into which the first gas is introduced are blocked in the raw material gas flow. Before the road, even if the production is interrupted and scraped off with a metallurgy or the like, it will adhere to the glass firmly, and sometimes the glass will be damaged.

[Previous Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent No. 4145923

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2006-52099

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2011-184235

[Non-patent literature]

[Non-Patent Document 1] Kosuke Daisuke, Terada Kazuo, Abe Ryu, Otani, and the 98th Catalyst Workshop (September, 1999), Seminar A Pre-collection, 234 pages

[Non-Patent Document 2] Hua Gui Yang et al., Nature, Vol. 453, p. 638~p.641

[Non-Patent Document 3] Amano F. et al., Chem. Mater., 21, 2601~2603 (2009)

[Summary of the Invention]

The present invention has been made in view of the above circumstances, and an object of the invention is to provide a method for producing metal oxide particles of metal oxide particles having high photocatalytic activity for a long period of time.

In the reaction tube, the pre-heated metal chloride-containing gas containing the metal chloride is combined with the preheated first gas at a temperature higher than the preheating temperature of the gas containing the metal chloride. a gas containing a metal chloride is heated, and after heating, a combined gas having a temperature higher than a preheating temperature of the metal chloride-containing gas is combined with the second gas which is preheated at a temperature equal to or higher than the temperature of the combined gas. In the method for producing a reheated gas, it is found that the metal oxide particles having high photocatalytic activity can be produced for a long period of time without containing oxygen or water vapor in both of the gas containing the metal chloride and the first gas. The following invention.

In order to achieve the above object, the present invention adopts the following Composition. that is,

(1) A method for producing metal oxide particles, which comprises a method for producing metal oxide particles according to the following steps, wherein the step is carried out in a reaction tube, and the preheated metal chloride-containing gas is not contained The first gas after the preheating of the metal chloride is merged at the first junction point, and the second gas which is preheated without the metal chloride and the first condensed gas is used as the first merging gas. The second confluence point on the downstream side of the first confluence point is merged, and as the second confluent gas, both the metal chloride-containing gas and the first gas do not contain oxygen or water vapor. (2) the gas contains at least oxygen, and the first gas is merged at the first junction point by setting the preheating temperature of the first gas to a temperature equal to or higher than a preheating temperature of the gas containing the metal chloride. 1 merging point to the second merging point (referred to as the first zone), reheating the preheated gas containing the metal chloride, and setting the preheating temperature of the second gas to the foregoing 1 combined gas Temperature or higher, and the first merged gas confluence by the second merging point on the downstream side, the first reheat merged gas.

(2) The method for producing metal oxide particles according to the above (1), wherein the metal chloride is titanium tetrachloride, and the metal oxide particles are titanium oxide particles.

(3) The method for producing metal oxide particles according to the above item (2), wherein the titanium oxide particles are decahedral titanium oxide particles.

(4) A metal oxide grain according to any one of items (1) to (3) above. In the method for producing a gas, the preheating temperature of the gas containing the metal chloride is 600 ° C or more and 1000 ° C or less.

(5) The method for producing a metal oxide particle according to any one of the preceding claims, wherein the temperature of the first merging gas is 800 ° C or more and 1050 ° C or less.

(6) The method for producing a metal oxide particle according to any one of the preceding claims, wherein the temperature of the second merging gas is 800 ° C or more and 1100 ° C or less.

(7) The method for producing a metal oxide particle according to any one of the preceding claims, wherein the preheating temperature of the first gas is 800 ° C or more and 1050 ° C or less.

The method for producing a metal oxide particle according to any one of the preceding claims, wherein the second gas has a preheating temperature of from 900 ° C to 1100 ° C.

(9) The method for producing a metal oxide particle according to any one of the items (1) to (8), wherein the gas containing the metal chloride contains nitrogen.

(10) The method for producing a metal oxide particle according to any one of the preceding claims, wherein the first gas contains one or more gases selected from the group consisting of nitrogen gas and argon.

The method for producing a metal oxide particle according to any one of the preceding claims, wherein the second gas contains an oxygen gas and one or more selected from the group consisting of nitrogen gas, argon gas and water vapor. gas.

(12) A metal oxide according to any one of items (2) to (11) above. In the method for producing particles, the concentration of the titanium tetrachloride contained in the first merging gas is 0.1 to 20% by volume.

The method for producing metal oxide particles according to any one of the preceding claims, wherein the time during which the first merging gas stays in the first region is 2 to 100 milliseconds.

The method for producing metal oxide particles according to any one of the preceding claims, wherein the Reynolds number of the second merging gas is from 10 to 10,000.

According to the above configuration, it is possible to provide a method for producing metal oxide particles of metal oxide particles having high photocatalytic activity for a long period of time.

The method for producing a metal oxide particle according to the present invention is a method for producing a metal oxide particle having the following steps, wherein the step is carried out in a reaction tube, and the preheated metal chloride-containing gas and the metal chloride are not contained therein. The first gas after the preheating of the compound is merged at the first joining point, and the second combined gas which is not preheated without the metal chloride is separated from the first combined gas as the first combined gas. a second confluence point on the downstream side of the first confluence point merges as a second confluent gas step,

When both the gas containing the metal chloride and the first gas do not contain oxygen or water vapor, the preheating temperature of the first gas is equal to or higher than the preheating temperature of the gas containing the metal chloride. Temperature, make the front The first gas merges at the first junction point, and the preheating of the second gas is performed by heating the preheated gas containing the metal chloride from the first junction point to the second junction point. When the temperature is equal to or higher than the temperature of the first merging gas, the first merging gas is merged with the second merging point, and the first merging gas is heated on the downstream side to produce a high photocatalytic activity for a long period of time. Metal oxide particles.

In the method for producing metal oxide particles of the present invention, the metal chloride is titanium tetrachloride, and the metal oxide particles produced are preferably titanium oxide particles. In this case, the gas containing the metal chloride and Each of the first gas does not contain oxygen or water vapor, and the preheating temperature of the first gas is a temperature equal to or higher than a preheating temperature of a gas containing the metal chloride, and the first gas is in the first a confluence point merges between the first confluence point and the second confluence point, and further heats the preheated gas containing the metal chloride, and sets a preheating temperature of the second gas as the first confluence The temperature above the temperature of the gas is merged with the first merging gas, and the first merging gas is heated on the downstream side from the second merging point, whereby the titanium oxide particles having high photocatalytic activity can be produced for a long period of time.

An apparatus for producing a metal oxide particle according to the present invention includes: a reaction tube; and a preheating unit that preheats a metal chloride-containing gas, a first gas, and a second gas, respectively, wherein the reaction tube includes a hollow outer tube, a second hollow inner cylinder formed by inserting the upstream side of the hollow outer cylinder into the hollow outer cylinder and inserting the second one from the upstream side of the second hollow inner cylinder a first hollow inner cylinder formed in the middle of the hollow inner cylinder, wherein the second hollow inner cylinder includes a first duct that introduces the preheated first gas to the upstream side thereof, and the hollow outer cylinder includes: The second conduit introduced into the upstream side of the second gas after the heat is introduced from the upstream side of the first hollow inner cylinder by the preheated gas containing the metal chloride, and introduced into the metal chloride The gas merges with the preheated first gas at a downstream end of the first hollow inner cylinder, and the merged gas may be at a downstream end of the second hollow inner cylinder and the preheated second gas By recombining, metal oxide particles having high photocatalytic activity can be produced for a long period of time.

1‧‧‧ hollow outer cylinder

1a‧‧‧ upstream side

1b‧‧‧ downstream side

2‧‧‧Insulation material (ceramic fiber)

3‧‧‧Product Recycling Department

3a‧‧‧Exhaust pump

3b‧‧‧Pressure adjustment valve

4‧‧‧1st hollow inner tube

4a‧‧‧ upstream side

4b‧‧‧ downstream end (1st junction location)

5‧‧‧2nd hollow inner tube

5a‧‧‧ upstream side

5b‧‧‧ downstream end (2nd merge point)

6‧‧‧Draining tube

11‧‧‧Reaction tube

15‧‧‧1st catheter

16‧‧‧2nd catheter

24‧‧‧1st hollow inner tube opening

25, 26‧‧‧ annular opening

27‧‧‧2nd hollow inner cylinder opening

28‧‧‧ hollow outer cylinder opening

101‧‧‧Manufacturing device for metal oxide particles

A‧‧‧2nd reaction zone

B‧‧‧District 1

G1‧‧‧Gas containing metal chlorides

G2‧‧‧1st gas

G3‧‧‧2nd gas

X‧‧‧Preheating area

Y‧‧‧Preheating area

Z‧‧‧Preheating area

Fig. 1 is a schematic view showing an example of a production apparatus of metal oxide particles of the present invention.

Fig. 2 is a scanning electron micrograph of metal oxide particles (titanium oxide particles) of Example 1, taken at 100k magnification.

Hereinafter, a method and a production apparatus for producing metal oxide particles to which an embodiment of the present invention is applied will be described in detail using the drawings. In addition, in the following description, the drawing used is not shown to be the same as the actual size in order to make the feature easier to understand, and to show it in a simplified manner.

<Manufacturing device for metal oxide particles>

Fig. 1 is a schematic view showing an example of a production apparatus used in a method for producing metal oxide particles according to an embodiment of the present invention.

As shown in Fig. 1, the manufacturing apparatus 101 used in the method for producing metal oxide particles according to the embodiment of the present invention includes a hollow outer cylinder 1 and an outer side (upstream portion) 1a of the hollow outer cylinder 1 inserted into the hollow outer portion. The second hollow inner cylinder 5 formed in the middle of the cylinder 1 and the reaction tube 11 formed of the first hollow inner cylinder 4 formed by the upstream side 5a of the second hollow inner cylinder 5 inserted into the second hollow inner cylinder 5 At the same time, the heat insulating material 2 is disposed outside the reaction tube 11, and a part of the reaction tube 11 is thermally insulated.

<reaction tube>

As shown in FIG. 1, the reaction tube 11 has a hollow outer cylinder 1, a first hollow inner cylinder 4, and a second hollow inner cylinder 5. The reaction tube 11 is composed of a cylindrical tube made of, for example, quartz.

The second hollow inner cylinder 5 is formed by inserting the upstream side 1a of the hollow outer cylinder 1 in the middle, and the downstream end 5b is disposed in the vicinity of the center of the hollow outer cylinder 1 in the longitudinal direction. The first hollow inner cylinder 4 is formed by inserting the upstream side 5a of the second hollow inner cylinder 5 in the middle, and the downstream end 4b is disposed in the vicinity of the center in the longitudinal direction of the second hollow inner cylinder 5.

<Gas containing metal chloride>

The metal chloride-containing gas G1 that has been preheated in the preheating zone (preheating section) X flows into the first hollow inner cylinder opening portion 24 of the upstream side 4a of the first hollow inner cylinder 4.

Although omitted in the drawing, a gasifier for evaporating metal chloride such as titanium tetrachloride (TiCl ₄ ) is provided on the upstream side of the preheating zone X, and on the upstream side of the gasifier, liquid is used. The metal chloride is introduced into the inlet pipe for the gasifier, and the introduction pipe for supplying the nitrogen-containing gas is connected to the vaporizer via a valve. The gasifier has, for example, a temperature of 165 ° C, and has a function of vaporizing a metal chloride of a liquid to form a metal chloride vapor. Thereby, it is possible to supply the metal chloride-containing gas G1 formed of a mixed gas containing a metal chloride vapor and nitrogen to the preheating zone X.

The metal chloride-containing gas G1 is a gas containing a vapor such as titanium tetrachloride. Specifically, as the gas G1 containing the metal chloride, a mixed gas of a vapor of nitrogen tetrachloride or the like and a mixed gas of nitrogen, a vapor such as titanium tetrachloride, and an inert gas containing nitrogen can be used.

<1st gas>

In the ring-shaped opening 25 between the downstream side 4b of the first hollow inner cylinder 4 and the upstream side 5a of the second hollow inner cylinder 5, the inflow preheating zone (preheating section) Y is preheated. After the first gas G2.

The first gas G2 is a gas containing no metal chloride such as titanium tetrachloride or oxygen or water vapor. Specifically, the first gas G2 is provided with an inert gas such as nitrogen or argon, and these may be used singly or in combination. Therefore, a gas formed only of nitrogen gas, a gas formed only of argon gas, a mixed gas of inert gas such as nitrogen and argon, or the like can be used.

<2nd gas>

The second gas G3 preheated in the preheating zone (preheating zone) Z flows into the annular opening portion 26 between the downstream side 5b of the second hollow inner cylinder 5 and the upstream side 1a of the hollow outer cylinder 1.

The second gas G3 is a gas containing no metal chloride such as titanium tetrachloride. Specifically, the second gas G3 contains at least oxygen (O ₂ ). Further, the second gas G3 may contain an inert gas such as oxygen, nitrogen or argon, water vapor, ozone, or ozone (O ₃ ) or a mixture thereof. Therefore, the second gas G3 can be in a state of only oxygen, a mixed gas state of an inert gas such as nitrogen or argon, a mixed gas state of water vapor and oxygen, a state of a mixed gas of an inert gas and steam and oxygen, and the like. . Further, air may be used as the mixed gas of the inert gas and oxygen.

It is preferable that the first hollow inner cylinder 4 and the second hollow inner cylinder 5 have a coaxial structure. Thereby, the metal chloride-containing gas G1 can be concentrated on the central axis side, and the titanium tetrachloride vapor can be prevented from diffusing to the inner wall surface of the second hollow inner cylinder 5, and adhesion to the inner wall surface of the second hollow inner cylinder 5 can be suppressed. Membrane product (by-product).

Further, it is preferable that the second hollow inner cylinder 5 and the hollow outer cylinder 1 have a coaxial structure. Thereby, the diffusion of the titanium tetrachloride vapor to the inner wall surface of the hollow outer cylinder 1 is suppressed, and the film-like product (by-product) adhering to the inner wall surface of the first hollow outer cylinder 1 can be suppressed.

<Insulation material>

As shown in Fig. 1, a heat insulating material 2 for heat-insulating the gas in the reaction tube is disposed outside the reaction tube 11. The insulating agent uses a usual ceramic fiber.

<1st merge point>

The metal chloride-containing gas G1 and the first gas G2 are joined to the downstream end 4b of the first hollow inner cylinder 4. The confluence of the two is called the first confluence location.

<1st merged gas>

The gas merged at the first junction site is referred to as a first merged gas.

<2nd merge point>

The first merging gas and the second gas G3 are joined to the downstream end 5b of the second hollow inner cylinder 5. The confluence of the two is called the second confluence location.

<2nd merged gas>

The gas merged at the second junction site is referred to as a second junction gas.

<zone 1>

Between the first joining point (the downstream end 4b of the first hollow inner cylinder 4) and the second joining point (the downstream end 5b of the second hollow inner cylinder 5), the region through which the first merged gas passes is referred to as the first region.

<2nd reaction zone>

The region where the second merged gas passes between the second joining point (the downstream end 5b of the second hollow inner cylinder 5) and the downstream end of the heat insulating material 2 is referred to as a second reaction zone. In the second reaction zone, the titanium tetrachloride in the second combined gas is steamed Gas is consumed by the oxidation reaction.

<preheating area>

In the apparatus 101 for manufacturing metal oxide particles according to the embodiment of the present invention, three preheating zones X, Y, and Z are provided.

An electric heater (not shown) or the like is disposed outside the gas flow path of each of the preheating zones X, Y, and Z. In the preheating zone X, Y, and Z, each of the metal chloride-containing gas G1, the first gas G2, and the second gas G3 is a specific preheating temperature.

The preheating temperature of the preheating zone X (the preheating temperature of the metal chloride-containing gas G1) is preferably a temperature range of 600 ° C or more and 1000 ° C or less, more preferably a temperature range of 650 ° C or more and 950 ° C or less, and further It is preferably in the temperature range of 800 ° C or more and 950 ° C or less.

Since the range of the preheating temperature of the preheating zone X is set to be less than 600 ° C, the photocatalytic activity of the finally obtained powder product is lowered. Further, since the range of the preheating temperature of the preheating zone X is set to be in the range of 1000 ° C or more, the ratio of rutile is high, and the ratio of the decahedron is lowered, the photocatalytic activity of the finally obtained powder product is lowered.

By setting the preheating temperature range of the preheating zone X to 600 ° C or more and 1000 ° C or less, the ratio of the decahedral titanium oxide particles in the finally obtained powder product is high, and as a result, a decahedron having high photocatalytic activity can be obtained. Titanium oxide particles.

Preheating temperature of preheating zone Y (preheating temperature of first gas G2) is preheating temperature of preheating zone X (gas containing metal chloride) The temperature above the preheating temperature of G1 is preferably in the range of 800 ° C or more and 1050 ° C or less, more preferably 850 ° C or more and 1050 ° C or less.

The preheating temperature of the first gas G2 is set to a temperature equal to or higher than the preheating temperature of the metal chloride-containing gas G1, and the metal chloride is preheated in the preheating zone X by the preheating zone X in the first zone. The gas G1 is reheated, and the ratio of the decahedral titanium oxide particles in the finally obtained powder product is high, and the photocatalytic activity is increased. On the contrary, when the preheating temperature of the first gas G2 is set to be lower than the preheating temperature of the metal chloride-containing gas G1, the ratio of the decahedral titanium oxide particles in the finally obtained powder product is low, and the photocatalyst is low. Reduced activity.

When the preheating temperature of the preheating zone Y is in the temperature range of less than 800 ° C, the ratio of the decahedral titanium oxide particles of the obtained powder product is low, and the photocatalytic activity is low. When the preheating temperature of the preheating zone Y is higher than 1050 ° C, the rutile ratio of the obtained powder product is increased, the proportion of the decahedral titanium oxide particles is low, and the photocatalytic activity is lowered. When the preheating temperature of the first gas G2 is set to a temperature range of 800 ° C or more and 1050 ° C or less above the preheating temperature of the metal chloride-containing gas G1, the ratio of the rutile in the finally obtained powder product is lowered, and the ten sides are reduced. The proportion of the bulk titanium oxide particles is increased, and as a result, decahedral titanium oxide particles having high photocatalytic activity can be obtained.

The preheating temperature of the preheating zone Z (preheating temperature of the second gas G3) is a temperature equal to or higher than the preheating temperature of the preheating zone Y (preheating temperature of the first gas G2), preferably 900 ° C or more and 1100 ° C or less. The temperature range is more preferably in the range of 950 ° C to 1050 ° C. The preheating temperature of the second gas G3 is set to a temperature equal to or higher than the temperature of the first merging gas, The second merging point merges the two, and by heating the first merging gas in the second reaction zone, particles having a high decahedron ratio and high photocatalytic activity can be obtained.

When the preheating temperature of the preheating zone Z is lower than 900 ° C, the temperature of the second merging gas, that is, the temperature of the second reaction zone is lowered, and the reaction in the second reaction zone is not completed, and sometimes the result is obtained. The case where the yield of the powder product is lowered. When the preheating temperature of the preheating zone Z is higher than the temperature range of 1100 ° C, the proportion of rutile in the finally obtained powder product increases, and the proportion of the decahedral titanium oxide particles decreases, and as a result, the photocatalytic activity decreases.

<1st merged gas temperature>

In the reaction tube 11, the first region B is provided between the first merging point (the downstream end 4b of the first hollow inner cylinder 4) and the second merging point (the downstream end 5b of the second hollow inner cylinder 5). In the first zone B, the pre-heated metal chloride-containing gas G1 merges with the preheated first gas G2 to form a first merged gas, and the first merged gas flows until it merges with the second gas G3. Area.

The temperature of the first merging gas is preferably a temperature range of 800 ° C or more and 1050 ° C or less, more preferably 850 ° C or more and 1000 ° C or less, and still more preferably 900 ° C or more and 1000 ° C or less. By setting the temperature of the first merging gas to a temperature range of 800 ° C or more and 1050 ° C or less, the ratio of the decahedral titanium oxide particles in the finally obtained powder product is increased, and high photocatalytic activity can be obtained.

The temperature of the first merged gas is less than 800 ° C, and finally The proportion of the decahedral titanium oxide particles in the obtained powder product is lowered, and the photocatalytic activity is lowered. When the temperature of the second merging gas is higher than 1050 ° C, the rutile ratio of the finally obtained powder product is increased, and the photocatalytic activity is lowered.

In the method of calculating the first merging gas temperature T ₁ [° C.], titanium tetrachloride and nitrogen are used for the gas G1 containing metal chloride, nitrogen is used for the first gas G2, and oxygen is used for the second gas G3 as an example.

Let T ₁ =Q ₁ /C ₁ , Q ₁ =Q _R,T +Q _R,N +Q _1G,N ,Q _R,T =G _{R, T} ×Cp _T ×T _R ,Q _R,N =G _{R, N} × Cp _N × T _R , Q _{1G, N} = G _{1G, N} × Cp _N × T _1G , G ₁ = G _{R, T} × Cp _T + G _{R, N} × Cp _N + G _{1G, N} × Formula calculation of Cp _N.

Here, Q ₁ G1-based metal chloride-containing gas by the gas G2 into the first sum of the amount of heat of the first merging point [kcal], C ₁ based on heat capacity of the gas merging [kcal / ℃], Q _{R, T} by containing titanium-based metal chlorides in the gas G1 tetrachloride into the merging point of the first heat _[kcal], Q _{R, N} G1-based metal chloride-containing gas by the nitrogen in the strip The heat entering the first junction (kcal), Q _{1G, N} is the heat brought into the first junction by the nitrogen in the first gas G2 [kcal], and the G _{R and T} are contained in the gas G1 containing the metal chloride. The mass flow rate of titanium tetrachloride [kg/h], the specific heat of Cp _T- based titanium tetrachloride [kcal/(kg‧°C)], the preheating temperature of T _R- based gas G1 containing metal chloride, G _{R N-} type mass flow rate of nitrogen in gas G1 containing metal chloride [kg/h], specific heat of Cp _N-type nitrogen [kcal/(kg‧°C)], G _{1G, nitrogen in N-type} first gas G2 the mass flow rate [kg / h], the specific heat Cp _N lines of N [kcal / (kg‧ ℃)] , T 1G -based gas G2 of the first preheating temperature [deg.] C]. Calculated by Cp _T = 0.6 [kcal / (kg ‧ ° C)], Cp _N = 1.2 [kcal / (kg ‧ ° C)]

<2nd merged gas temperature>

In the reaction tube 11, a second reaction zone A is provided between the downstream end 5b of the second hollow inner cylinder 5 and the downstream end of the heat insulating material 2. In the second reaction zone A, the first merged gas merges with the preheated second gas G3 to form a second merged gas, and is a region where the second merged gas flows. In the present embodiment, the outer side of the hollow outer cylinder 1 is separated. In the region where the hot material 2 is wound, the gas in the reaction tube 11 can be kept warm in the second reaction zone A by winding the heat insulating material. The temperature of the second merging gas is preferably a temperature range of 800 ° C or more and 1100 ° C or less, more preferably a temperature range of 800 ° C or more and 1050 ° C or less, and still more preferably a temperature range of 850 ° C or more and 1050 ° C or less. By setting the temperature of the second merging gas to a temperature range of 800 ° C or more and 1100 ° C or less, the ratio of the decahedral titanium oxide particles in the finally obtained powder product is increased, and high photocatalytic activity can be obtained.

When the temperature of the first merging gas is less than 800 ° C, the ratio of the decahedral titanium oxide particles in the finally obtained powder product is lowered, and the photocatalytic activity is lowered. When the temperature of the second merging gas is higher than 1100 ° C, the rutile ratio of the finally obtained powder product is increased, and the photocatalytic activity is lowered.

In the method of calculating the second combined gas temperature T ₂ [° C.], titanium tetrachloride and nitrogen are used for the gas G1 containing metal chloride, nitrogen is used for the first gas G2, and oxygen is used for the second gas G3 as an example.

Let T ₂ =Q ₂ /C ₂ , Q ₂ =Q _1,T +Q _1,N +Q _2G,O ,Q _1,T =G _{1 , T} ×Cp _T ×T ₁ ,Q _1,N =G _{1, N} × Cp _N × T ₁ , Q _{2G, O} = G _{2G, O} × Cp _O × T _2G , C ₂ = G _{1 , T} × Cp _T + G _{1 , N} × Cp _N + G _{2G, O} × Formula calculation of Cp _O.

Here, Q ₂ is a total amount of heat taken by the first merging gas and the second gas G3 to the second merging point [kcal], and C ₂ is a heat capacity of the second merging gas [kcal/°C], Q _{1, T} is the heat [kcal] brought into the second junction by the titanium tetrachloride in the first merging gas, and Q _{1, N} is the heat brought into the second junction by the nitrogen in the first merging gas [kcal] ], Q _{2G, O} is the amount of heat brought into the second junction by the oxygen in the second gas G3 [kcal], and the mass flow rate of titanium tetrachloride in the first confluent gas of G _{1 and T} is [kg/h] ], G _{1 , N} is the mass flow rate of nitrogen in the first combined gas [kg / h], G _{2G, O} is the mass flow rate of oxygen in the second gas G3 [kg / h], T _2G based second gas Preheating temperature of G3 [°C]. The calculation was carried out with Cp _T = 0.60 [kcal / (kg ‧ ° C)], Cp _O = 1.1 [kcal / (kg ‧ ° C)], Cp _N = 1.2 [kcal / (kg ‧ ° C)]

<Product Recycling Department>

The downstream side 1b of the hollow outer cylinder 1 is connected to a product recovery part 3 that recovers a product such as metal oxide particles via a discharge pipe 6. The product recovery unit 3 is composed of a bag filter or the like, and the generated metal oxide particles can be recovered.

Further, an exhaust pump 3a and a pressure regulating valve 3b are connected to the downstream side of the product recovery unit 3. Usually, the product is accumulated in the product recovery unit 3, and as the filter is clogged, the internal pressure of the reaction tube 11 rises. By the suction of the exhaust pump 3a, the pressure rise can be suppressed, and an oxidation reaction can be generated to the metal oxide in the vicinity of the normal pressure. Further, at this time, it is preferable to adjust the pressure adjusting valve 3b and adjust the suction force of the exhaust pump 3a. Thereby, metal oxide particles can be produced more efficiently.

When titanium tetrachloride is used as the metal chloride, the metal oxide particles recovered by the product recovery unit 3 are decahedral titanium oxide particles or titanium oxide particles other than the particles. The decahedral titanium oxide particles are titanium oxide particles having a decahedral box shape as in the definition of Patent Document 1.

Further, the titanium oxide particles other than the decahedral titanium oxide particles are those defined by the above-described decahedral titanium oxide particles among the titanium oxide particles obtained by the production method of the present embodiment.

<Method for Producing Metal Oxide Particles>

Next, a method for producing metal oxide particles according to an embodiment of the present invention will be described using a manufacturing apparatus 101 for metal oxide particles shown in Fig. 1 .

The method for producing metal oxide particles according to the embodiment of the present invention includes a metal chloride-containing gas G1 containing a metal chloride, a first gas G2 not containing the metal chloride, and a metal chloride-free a step of preheating the second gas G3 (hereinafter referred to as a preheating step), and combining the gas G1 containing the metal chloride with the first gas G2 to form a first merging gas, and the first merging gas and the The second gas G3 merges to form a second merging gas, and the metal chloride is reacted in the second reaction zone.

The case of using titanium tetrachloride as a metal chloride to form titanium oxide as a metal oxide particle will be described below.

<Preheat step>

The metal chloride-containing gas G1 which is preheated in the preheating zone X at a predetermined preheating temperature flows in from the upstream side 4a of the first hollow inner cylinder 4.

The mixed gas (first gas G2) composed of nitrogen which is preheated in the preheating zone Y at a predetermined preheating temperature flows into the annular opening portion 25 between the first hollow inner cylinder and the second hollow inner cylinder.

The mixed gas (second gas G3) composed of oxygen, nitrogen, and water vapor which is preheated in the preheating zone Z at a predetermined preheating temperature flows into the annular opening between the second hollow inner cylinder and the hollow outer cylinder 1. In section 26.

The metal chloride-containing gas G1 discharged from the downstream end 4b of the first hollow inner cylinder 4 and the first gas G2 discharged from the annular opening 25 merge at the downstream end 4b of the first hollow inner cylinder 4 to form the first Confluence gas. In other words, the downstream end 4b of the first hollow inner cylinder 4 serves as a joining point (first joining point).

<Reaction step>

In the second reaction zone A, the oxidation reaction of the reaction formula (1) is carried out at the temperature of the second combined gas, and the titanium tetrachloride is converted into titanium oxide. When the second merging gas passes through the second reaction zone A, the metal oxide in the merging gas is rapidly cooled to form a powder product of the titanium oxide particles.

The second confluent gas is retained in the second reaction zone A for a period of time, preferably less than 300 milliseconds, more preferably less than 200 milliseconds, and even more preferably less than 150 milliseconds. When the distance of the heat insulating material 2 in the direction of the reaction tube axis becomes long, and the time when the second condensed gas stays in the second reaction zone A of the heat retention zone is 300 msec or more, aggregation occurs between the particles, and the specific surface area is lowered, and the obtained powder product is obtained. Photocatalytic activity is reduced.

A method of calculating the time t ₂ at which the second merging gas is retained in the second reaction zone is shown. Let t ₂ = L ₂ /Ve _{2, T2} , Ve _{2, T2} = Vo _{2, T2} / S _2R , Vo _{2, T2} = Vo _{2, 0 ° C} × (273.15 + T ₂ ) / 273.15, Vo _{2, 0 ° C} =Vo _{1 , 0° C} +Vo _{2G, 0°C,} Vo _{1 , 0° C} =Vo _{R, 0°C} +Vo _{1G, 0°C} .

Here, L ₂ is the length [m] of the reaction tube axis direction of the second reaction zone, and Ve _{2 and T2} are the second combined gas temperature conversion values [m/s] and Vo ₂ of the linear velocity of the second merged gas _{. T2} is the second combined gas temperature conversion value [m ³ /s] of the second combined gas flow rate, S _2R is the sectional area of the second reaction zone [m ² ], and Vo _{2 and 0 ° C} are ₀ of the second combined gas flow rate. °C converted value, T ₂ is the second combined gas temperature, Vo ₁ , _{0 ° C} is the 0 ° C converted value of the first combined gas flow rate, Vo _{2G, 0 ° C} is the 0 ° C converted value of the second gas G3 flow rate, Vo _{R, 0 ° C} is a 0 ° C converted value of the flow rate of the gas G1 containing the metal chloride, and Vo _{1G and 0 °} C are converted values of 0 ° C of the flow rate of the first gas G2.

On the downstream side of the heat insulating material 2, in order to suppress coagulation between particles It is preferred to effectively cool the gas in the reaction tube. The method includes, for example, a method of naturally dissipating heat from the wall surface of the reaction tube, blowing cooling air outside the reaction tube, and introducing cooling air into the reaction tube.

[concentration of titanium tetrachloride]

In the region 27 from the downstream end 4b of the first hollow inner cylinder 4 to the downstream end 4b of the second hollow inner cylinder 5, the metal chloride-containing gas G1 and the first gas G2 merge at the first junction point. The concentration of titanium tetrachloride in the combined gas is preferably from 0.1 to 20% by volume, more preferably from 0.5 to 10% by volume, still more preferably from 0.5 to 5% by volume. By setting the concentration of titanium tetrachloride in the first merging gas to the above range, decahedral titanium oxide particles having high photocatalytic activity can be obtained.

Further, in the region 27, the lower the concentration of titanium tetrachloride in the first merging gas flowing through the first region, the smaller the primary particle diameter of the titanium oxide particles constituting the finally obtained powder product, and the larger the specific surface area. By setting the concentration of titanium tetrachloride in the first merging gas flowing through the first zone to the above range, a powder product having high photocatalytic activity can be obtained.

[stagnation time]

The time during which the first merging gas stays in the first zone (hereinafter referred to as "stagnation time") is preferably in the range of 2 to 100 milliseconds, more preferably in the range of 2 to 75 milliseconds, and more preferably 20 to 50. Within the range of milliseconds.

By setting the second junction point away from the downstream side of the first junction point, the first zone is provided, and the first merged gas is retained in the first zone. time.

At this time, a trace amount of the second gas (second flammability gas) is reversed. Therefore, in the case where the residence time exceeds 100 msec, in the first zone, the titanium oxide adherend, the film-like product, and the deposit are easily formed on the inner wall surface of the second hollow inner cylinder (particularly, the edge of the downstream end 5b). The yield of the obtained powder product was lowered, or the flow path was blocked, and the quartz glass was broken. Also, the rutile ratio increases and the photocatalytic activity decreases.

On the other hand, when the residence time is less than 2 milliseconds, a plurality of titanium oxide adherends are likely to be generated at the front end or the periphery of the first hollow inner cylinder quartz tube, and eventually the flow path is clogged and the quartz glass is broken. Although the rutile ratio is lowered, the photocatalytic activity of the finally obtained titanium oxide particles is lowered.

When the time during which the first confluent gas is retained in the first region is in the range of 2 to 100 msec, the titanium oxide adherend, the film-like product, and the deposit are not generated in the first and second hollow inner cylinder quartz tubes. More than % of the high yield is produced for a long time.

Further, the ratio of the rutile of the titanium oxide particles finally obtained is low, and the proportion of the decahedral titanium oxide particles in the powder product is increased, and the photocatalytic activity is increased.

A method of calculating the time t _{1 at which} the first merging gas stays in the first region is displayed. Let t ₁ = L ₁ /Ve _{1 , T1} , Ve _{1 , T1} = Vo _{1 , T1} / S _1G , Vo _{1 , T1} = Vo _{1 , 0 ° C} × (273.15 + T ₁ ) / 273.15, Vo _{1, 0 ° C} =Vo _{R, 0°C} +Vo _{1G, 0°C} formula calculation.

Here, L ₁ is the length [m] of the reaction tube axis direction of the first zone, and Ve _{1 and T1} are the first combined gas temperature conversion values [m/s], Vo _{1 and T1} of the linear velocity of the first merged gas _. The first combined gas temperature conversion value [m ³ /s] of the first combined gas flow rate, the S _1G is the first area sectional area [m ² ], Vo ₁ , and _{0 ° C} is the first combined gas flow rate of 0 ° C conversion. The value, T ₁ is the first combined gas temperature, Vo _{R, 0 ° C} is a 0 ° C converted value of the metal chloride-containing gas G1 flow rate, and Vo _{1G and 0 ° C} are 0 ° C converted values of the first gas G2 flow rate.

[Reynolds number]

The Reynolds number of the second merging gas is preferably in the range of 10 to 10,000, preferably in the range of 1000 to 4,000, and more preferably in the range of 2100 to 3,000.

When the Reynolds number exceeds 10,000, the turbulent flow state of the merged gas becomes conspicuous, and the effect of suppressing the oxidizing gas which diffuses the titanium tetrachloride vapor from the vicinity of the central axis of the reaction tube 11 to the inner wall surface side is lost in the reaction tube 11 The amount of film-like product adhesion on the inner wall surface increases. When the Reynolds number of the second merging gas is less than 10, the case of a small flow rate due to laminar flow, or the case where the turbulent flow condition exceeds 10000, the proportion of the decahedral particles in the powder product is lowered, and the photocatalytic activity is decreased. Will also decrease. By setting the Reynolds number of the second merging gas to be in the range of 10 to 10,000, the proportion of the decahedral particles in the powder product is increased, and the photocatalytic activity is increased.

The Reynolds number Re is calculated by the calculation formula of Re = D × u × ρ / μ. Where D is the inner diameter (m) of the hollow outer cylinder 1, u is the linear velocity (m/s), ρ is the density (kg/m ³ ), and μ is the viscosity [kg/(m × s)].

In the present embodiment, the value of the inner diameter D of the hollow outer cylinder 1 is 126 (mm). Further, the value of u is the linear velocity (converted value of the second combined gas temperature) of the combined gas (Cl ₂ + O ₂ ) after the reaction in the second reaction zone. The value of ρ is the density of the combined gas (Cl ₂ + O ₂ ) after the reaction (the converted value of the second combined gas temperature). Further, the value of μ is the viscosity of the combined gas after the reaction (the second combined gas temperature conversion value).

[Line speed of confluent gas u]

The linear velocity u of the second combined gas (TiCl ₄ + O ₂ + N ₂ ) can be used as the value of the linear velocity u of the combined gas (Cl ₂ + O ₂ + N ₂ ) after the reaction in the second reaction zone. 2 Confluent gas temperature conversion value).

By reaction of Formula (1) described before, the case of TiCl ₄ gas G1 containing the metal chlorides contained in the entire consumed, addition of TiCl ₄ generates a 2-fold (flow) of the amount of Cl _2, at the same time, O ₂ Only the component of TiCl ₄ is consumed, and the flow of O ₂ is reduced. However, the generated TiO ₂ is a particle rather than a gas, and as a result, the flow rate of the gas flowing before and after the reaction does not change.

[density of gas ρ]

In order to calculate the value of the density ρ of the combined gas (Cl ₂ + O ₂ + N ₂ ) after the reaction in the second reaction zone, the flow rate of the combined gas after the reaction per unit time is used (that is, the second combined gas is used. flow).

First, the flow rate of the flow rate of the combined gas after the reaction in the second reaction zone is converted into the temperature of the second combined gas temperature as X _2T (m ³ /h). Using the flow rate in the standard state (0 ° C, 1 atm) of the flow rate of the combined gas after the reaction, X _2T (m ³ /h), the mass flow rate of the combined gas Y _{0 ° C, 1 atm} (kg / h). At this time, the density of the combined gas after the reaction in the second reaction zone is ρ = Y _{0 ° C, 1 atm} (kg) / X _2T (m ³ ).

In order to calculate the viscosity μ of the combined gas (Cl ₂ + O ₂ + N ₂ ) after the reaction in the second reaction zone, a calculation formula of μ = exp{a + b × ln(t + 273)} was used. In the above calculation formula, t is the temperature (° C.), and here is the temperature of the second merging gas. And, a, the constant b was due to the type of use of the gas to be determined, on Cl ₂ as a = 0.015, b = 0.864, on O ₂ as a = 1.289, b = 0.711, on N ₂ as a = 1.388, b A value of =0.668. Further, the values of a and b are values obtained by combining the known t and μ, and solving the cubic equation of a and b.

The viscosity μ of the combined gas (Cl ₂ +O ₂ +N ₂ ) after the reaction is averaged by the following formula, and the viscosity μ of the combined gas after the reaction (calculated as the second combined gas temperature) is obtained.

The viscosity μ of the combined gas after the reaction (the converted value of the second combined gas temperature) = {(the converted value of the second combined gas temperature of the flow rate of Cl ₂ ) × (the viscosity of the Cl ₂ converted by the temperature of the second combined gas) + (O ₂ the second merged gas temperature conversion value of the flow of) × (the second junction temperature of the gas in terms of O viscosity ₂ of) + (second merged gas temperature conversion value of N ₂ flow rate of) × (the second junction temperature of the gas in terms of N ₂ of Viscosity)}/{Flow of combined gas (Cl ₂ +O ₂ +N ₂ ) after reaction}

The titanium oxide particles as the metal oxide particles are described above as an example. However, the metal oxide particles may be cerium oxide particles or tin oxide particles, for example. In the case of producing such metal oxide particles, a metal chloride-containing gas containing ruthenium tetrachloride vapor and tin tetrachloride vapor, respectively, is used.

Further, titanium oxide particles are generated as metal oxide particles In the case of using a mixed gas composed of a vapor of titanium tetrachloride and nitrogen as a gas containing a metal chloride, it is preferable to use nitrogen gas for the first gas and oxygen gas for the second gas G3. By using this combination, particles having high photocatalytic activity can be produced for a long period of time.

According to the method for producing metal oxide particles according to the embodiment of the present invention, metal oxide particles having high photocatalytic activity can be produced for a long period of time. In particular, when titanium tetrachloride particles as metal oxide particles are produced using titanium tetrachloride as a metal chloride, the effect is remarkable.

In the method for producing metal oxide particles according to the embodiment of the present invention, since the titanium oxide particles are composed of decahedral titanium oxide particles, metal oxide particles having high photocatalytic activity can be produced for a long period of time.

In the method for producing metal oxide particles according to the embodiment of the present invention, since the preheating temperature of the metal chloride-containing gas G1 is 600° C. or higher and 1000° C. or lower, metal oxide particles having high photocatalytic activity can be produced for a long period of time. .

In the method for producing metal oxide particles according to the embodiment of the present invention, since the temperature of the first merging gas is 800° C. or higher and 1050° C. or lower, metal oxide particles having high photocatalytic activity can be produced for a long period of time.

In the method for producing metal oxide particles according to the embodiment of the present invention, since the temperature of the second merging gas is 800° C. or higher and 1100° C. or lower, metal oxide particles having high photocatalytic activity can be produced for a long period of time.

Manufacture of metal oxide particles according to an embodiment of the present invention In the method, since the preheating temperature of the first gas G2 is 800° C. or higher and 1050° C. or lower, metal oxide particles having high photocatalytic activity can be produced for a long period of time.

In the method for producing the metal oxide particles according to the embodiment of the present invention, since the preheating temperature of the second gas G3 is 800° C. or higher and 1100° C. or lower, the metal oxide particles having high photocatalytic activity can be produced for a long period of time.

In the method for producing metal oxide particles according to the embodiment of the present invention, since the gas G1 containing a metal chloride is a characteristic containing nitrogen gas, metal oxide particles having high photocatalytic activity can be produced for a long period of time.

In the method for producing a metal oxide particle according to the embodiment of the present invention, since the first gas G2 is composed of a gas selected from the group consisting of nitrogen gas and argon, it is possible to produce a metal oxide having high photocatalytic activity for a long period of time. Particles.

In the method for producing a metal oxide particle according to the embodiment of the present invention, since the second gas G3 is composed of a gas selected from the group consisting of oxygen gas, nitrogen gas, argon gas, and water vapor, it can be produced for a long period of time. Metal oxide particles with high photocatalytic activity.

In the method for producing metal oxide particles according to the embodiment of the present invention, since the concentration of the titanium tetrachloride contained in the first merging gas is 0.1 to 20% by volume, a metal having high photocatalytic activity can be produced for a long period of time. Oxide particles.

Manufacture of metal oxide particles according to an embodiment of the present invention In the method, since the time during which the first merging gas stays in the first region is 2 to 100 milliseconds, the metal oxide particles having high photocatalytic activity can be produced for a long period of time.

In the method for producing metal oxide particles according to the embodiment of the present invention, since the Reynolds number of the second merging gas is 10 to 10,000, metal oxide particles having high photocatalytic activity can be produced for a long period of time.

The apparatus for producing metal oxide particles according to the embodiment of the present invention includes a reaction tube 11 and preheating portions X, Y, and Z for preheating each of the metal chloride-containing gas G1, the first gas, and the second gas. The reaction tube 11 is a hollow outer cylinder 1, a second hollow inner cylinder 5 formed by inserting the upstream side 1a of the hollow outer cylinder 1 into the hollow outer cylinder 1, and a second hollow inner cylinder 5 The first hollow inner cylinder 4 formed by inserting the upstream side 5a into the second hollow inner cylinder 5, and the second hollow inner cylinder 5 is provided with the preheated first gas introduced into the upstream side 5a thereof. In the first duct 15, the hollow outer cylinder 1 includes a second duct 16 that introduces the preheated second gas to the upstream side 1a thereof, and the gas G1 containing the metal chloride after being preheated is used. The upstream side 4a of the first hollow inner cylinder 4 is introduced, and the introduced gas chloride G1 containing the metal chloride merges with the preheated first gas at the downstream end 4b of the first hollow inner cylinder 4, and the combined flow The gas may be recombined with the second gas after the preheating at the downstream end 5b of the second hollow inner cylinder 5 , It can be manufactured for a long time with high photocatalytic activity of metal oxide particles.

[Examples]

Hereinafter, the present invention will be specifically described based on examples. However, the present invention is not limited to the embodiments. The embodiment can be appropriately changed as long as it is not changed.

(Example 1) <Device preparation>

First, the hollow outer cylinder 1 uses a quartz tube having an inner diameter of 126.0 mm, and the first hollow inner cylinder 4 uses a quartz tube having an outer diameter of 27.0 mm, an inner diameter of 21.0 mm, and a thickness of 3.0 mm, and the second hollow inner cylinder 5 has an outer diameter of 61.0 mm. A quartz tube having an inner diameter of 55.0 mm and a thickness of 3.0 mm is disposed coaxially with the hollow outer cylinder 1 and the first hollow inner cylinder 4 and the second hollow inner cylinder 5 to produce a reaction tube 11.

Next, one part of the reaction tube 11 was wound with a heat insulating material (ceramic fiber) 2 by 50 cm, and the second reaction zone A was set. On the downstream side of the heat insulating material 2, the temperature of the gas in the reaction tube 11 is lowered by heat radiation to the outside of the reaction tube 11. Therefore, the length of the second reaction zone A is set by setting the length of the heat insulating material.

Next, the second hollow inner cylinder 5 is disposed such that the downstream end 5b of the second hollow inner cylinder 5 becomes the upstream end of the second reaction zone A. Since the downstream end 5b of the second hollow inner cylinder 5 is upstream, the second gas G3 preheated by the electric heater in the preheating zone Z is introduced into the upstream side 1a of the hollow outer cylinder 1.

Next, the first hollow inner cylinder 4 is disposed such that the downstream end 4b of the first hollow inner cylinder 4 is positioned upstream of the downstream end 5b of the second hollow inner cylinder. Since the downstream end 4b of the first hollow inner cylinder 4 is upstream, the first gas G2 preheated by the electric heater in the preheating zone Y is introduced into the upstream side 5a of the second hollow inner cylinder 5. The metal chloride-containing gas G1 which is preheated by the electric heater in the preheating zone X is introduced into the upstream side 4a of the first hollow inner cylinder 4. The length of the first zone B is 14.0 cm. The length of the second reaction zone A was 50.0 cm.

As described above, the apparatus 101 for manufacturing metal oxide particles shown in Fig. 1 is prepared.

<manufacturing step>

Then, the first gas G2 composed of nitrogen (N ₂ ) gas is introduced into the preheating zone Y at 1010 ° C by an electric heater to be 1010 ° C, and then introduced from the upstream side 5 a of the second hollow inner cylinder 5 . Further, the flow rate of the first gas G2 was 6.5 Nm ³ /h.

Next, the second gas G3 made of oxygen (O ₂ ) gas is passed through a preheating zone Z of 1030 ° C by an electric heater to be 1030 ° C, and then introduced from the upstream side 1 a of the hollow outer cylinder 1 . Further, the flow rate of the second gas G3 was 32 Nm ³ /h.

Next, the metal chloride-containing gas G1 made of titanium tetrachloride (TiCl ₄ ) and nitrogen (N ₂ ) gas is heated at 880 ° C in the preheating zone X by an electric heater to become 880 ° C. The upstream side 4a of the hollow inner cylinder 4 is introduced. Further, the flow rate of the metal chloride-containing gas G1 was 1.3 Nm ³ /h.

The total flow rate (feed gas flow rate) of the metal chloride-containing gas G1 and the first gas G2 and the second gas G3 was 39.8 Nm ³ /h.

The residence time of the first zone B of the first merged gas was set to 32 milliseconds. The residence time of the second reaction zone A of the second merging gas was set to 118 msec. Further, the concentration of titanium tetrachloride in the first merging gas in the first zone B was set to 3.8% by volume (vol%). The first combined gas temperature was 979 °C. The second combined gas temperature was 1020 °C. Further, the Reynolds number of the second merging gas in the second reaction zone A was 2,800.

In addition, this Reynolds number is assumed to be a value on the downstream side of the downstream end 5b of the second hollow inner cylinder 5, and the second merging gas is 1020 °C. In addition, the residence time in the first zone is assumed to be a value on the downstream side of the downstream end 4b of the first hollow inner cylinder 4, and the first merged gas is 979 °C. The residence time in the second reaction zone is assumed to be further downstream than the downstream end 5b of the second hollow inner cylinder 5, and the second merged gas is 1020 ° C, and the second merged gas is calculated from the downstream end 5b of the second hollow inner cylinder 5. The value of the residence time to the downstream end of the heat insulating material 2.

Finally, metal oxide particles obtained by the powder product were recovered in the product recovery section 3 (Example 1).

<Feature evaluation>

The property evaluation of the metal oxide particles (Example 1) was carried out as follows.

First, the yield of the powder product of the raw material was 97%. Further, the obtained powder product was titanium oxide particles.

"Yield of powder product" means all titanium tetrachloride used, relative The ratio of the mass of the titanium oxide product in the case where the reaction of the reaction formula (1) described above is converted into a titanium oxide product, and the mass of the actually produced powder product, that is, the mass of the titanium oxide particles.

Next, the ratio of the decahedral titanium oxide in the powder product was found to be 70% by observation with a scanning electron microscope.

The ratio of the decahedral titanium oxide particles (hereinafter referred to as "decahedral ratio") means that titanium oxide particles (arbitrarily sampled powder products) are observed in five or more fields by a scanning electron microscope to calculate titanium oxide particles. The proportion of decahedral titanium oxide particles contained in the material.

Moreover, FIG. 2 is a scanning electron micrograph in which the metal oxide particles (titanium oxide particles) of Example 1 were magnified 100 k times.

Further, the obtained particles had a specific surface area (BET) of 14 m ² /g.

Secondly, the rutile ratio was found to be 4% by X-ray diffraction measurement. The numerical value of the rutile ratio is a result obtained by estimating the ratio (%) of the titanium oxide particles of the rutile crystal structure by the peak intensity measured by X-ray diffraction.

Next, the photocatalytic activity of the titanium oxide after the production was evaluated by gas chromatography.

First, 10 mg of titanium oxide powder was placed in a disk (Schale) having an inner diameter of 27 mm, and water-dispersed, followed by drying at 110 °C.

Next, the disk was placed in a 500 ml chamber, and after replacing the inside with synthetic air, the irradiance was carried out under the condition of placing 500 ppm of acetaldehyde and 5.8 μl of water (corresponding to a relative humidity of 50% in 25 ° C). A light source of 0.2 mW/cm ² of the light source was used to quantify the amount of carbon dioxide (CO ₂ ) generated per hour by gas chromatography. As a result, the amount of carbon dioxide (CO ₂ ) which is photocatalytic activity is 120 ppm/h.

(Examples 2 to 4)

The flow rate of the first gas G2, the concentration of titanium tetrachloride in the first merging gas, the residence time of the first merging gas in the first zone B, and the residence time of the second merging gas in the second reaction zone A, The metal oxide particles of Examples 2 to 4 were produced in the same manner as in Example 1 except that the reciprocating gas temperature, the second merging gas temperature, and the Reynolds number of the second merging gas in the second reaction zone A were changed as shown in Tables 1 and 2. .

(Examples 5 to 7)

The amount of titanium tetrachloride supplied, the concentration of titanium tetrachloride in the first merging gas, the residence time of the first merging gas in the first zone B, and the residence time of the second merging gas in the second reaction zone A, The metal oxide particles of Examples 5 to 7 were produced in the same manner as in Example 1 except that the reciprocating gas temperature, the second merging gas temperature, and the Reynolds number of the second merging gas in the second reaction zone A were changed as shown in Tables 1 and 2. .

(Example 8)

The preheating temperature of the first gas G2, the residence time of the first merging gas in the first zone B, the residence time of the second merging gas in the second reaction zone A, the first merging gas temperature, and the second merging gas temperature The Reynolds number of the second merging gas in the second reaction zone A is changed as shown in Tables 1 and 2, and In the same manner as in Example 1, the metal oxide particles of Example 8 were produced.

(Example 9)

The preheating temperature of the first gas G2, the preheating temperature of the second gas G3, the residence time of the first merging gas in the first zone B, and the residence time of the second merging gas in the second reaction zone A, the first The metal oxide particles of Example 9 were produced in the same manner as in Example 1 except that the merging gas temperature, the second merging gas temperature, and the Reynolds number of the second merging gas in the second reaction zone A were changed as shown in Tables 1 and 2.

(Embodiment 10)

The preheating temperature of the second gas G3, the residence time of the second condensed gas in the second reaction zone A, the temperature of the second merging gas, and the Reynolds number of the second merging gas of the second reaction zone A are as shown in Tables 1 and 2. The metal oxide particles of Example 10 were produced in the same manner as in Example 1 except that the change was shown.

(Example 11)

The preheating temperature of the metal chloride-containing gas G1, the first merging gas temperature, the second merging gas temperature, and the Reynolds number of the second merging gas of the second reaction zone A are changed as shown in Tables 1 and 2, and are implemented. The metal oxide particles of Example 11 were produced in the same manner as in Example 1.

(Embodiment 12)

The preheating temperature of the gas chloride G1 containing the metal chloride, the first zone B Residual time of the first merging gas, retention time of the second merging gas in the second reaction zone A, temperature of the first merging gas, temperature of the second merging gas, and Reynolds number of the second merging gas of the second reaction zone A The metal oxide particles of Example 12 were produced in the same manner as in Example 1 except that the changes are shown in Tables 1 and 2.

(Comparative Example 1)

The manufacturing apparatus of Comparative Example 1 has the same configuration as the manufacturing apparatus 101 of the first embodiment. The metal oxide of Comparative Example 1 was produced in the same manner as in Example 1 except that the type of the first gas G2, the temperature of the first merging gas, and the Reynolds number of the second merging gas of the second reaction zone A were changed as shown in Tables 1 and 2. particle.

(Comparative Example 2)

The manufacturing apparatus of Comparative Example 2 also has the same configuration as the manufacturing apparatus 101 of the first embodiment. The amount of titanium tetrachloride supplied, the type of the first gas G2, the concentration of titanium tetrachloride in the first merging gas, the residence time of the first merging gas in the first zone B, and the second in the second reaction zone A The retention time of the merging gas, the temperature of the first merging gas, the temperature of the second merging gas, and the Reynolds number of the second merging gas of the second reaction zone A were changed as shown in Tables 1 and 2, and Comparative Example 2 was produced in the same manner as in Example 1. Metal oxide particles.

(Comparative Example 3)

The manufacturing apparatus of Comparative Example 3 also has the same configuration as the manufacturing apparatus 101 of the first embodiment. The type of the first gas G2 and the first one of the first region B The retention time of the flowing gas, the residence time of the second merged gas in the second reaction zone A, the temperature of the first merged gas, the temperature of the second merged gas, and the Reynolds number of the second merged gas of the second reaction zone A are shown in Table 1. The metal oxide particles of Comparative Example 3 were produced in the same manner as in Example 1 except for the change shown in Table 2.

(Comparative Example 4)

The manufacturing apparatus of Comparative Example 4 also has the same configuration as the manufacturing apparatus 101 of the first embodiment. The flow rate of the first gas G2, the concentration of titanium tetrachloride in the first merging gas, the residence time of the first merging gas in the first zone B, and the residence time of the second merging gas in the second reaction zone A, The metal oxide particles of Comparative Example 4 were produced in the same manner as in Example 1 except that the merging gas temperature, the second merging gas temperature, and the Reynolds number of the second merging gas in the second reaction zone A were changed as shown in Tables 1 and 2.

(Comparative Example 5)

For the purpose of comparison, commercially available titanium oxide particles for photocatalysts were purchased. The titanium oxide particles (Comparative Example 5) were particles synthesized by a flame method, and as a result of observation with an electron microscope, the particle shape was amorphous, and the primary particle diameter was 20 to 60 nm. Further, as a result of X-ray diffraction measurement, particles in which anatase and rutile were mixed were known.

Further, Table 3 shows the yields of the powder products of Examples 1 to 12 and Comparative Examples 1 to 5, the decahedral ratio in the powder product, the photocatalytic activity, the specific surface area (BET measurement value, m ² /g), and rutile. proportion.

In Comparative Examples 1 to 3 in which oxygen was circulated to the first flammable gas, titanium oxide deposits were hardly generated in the first and second hollow inner cylinder quartz tubes at the initial stage of production, but titanium oxide deposits were continued during production. Accumulate slowly, and the flow path is blocked within a total of 5 to 20 hours of production time. The quartz glass is broken. Therefore, it is known that production cannot be performed for a long time

In Comparative Example 3, the photocatalyst activity and the yield of the powder product were high in accordance with the production method described in Patent Document 3 (JP-A-2011-184235).

In Comparative Examples 1 and 2, the manufacturing method of the Japanese Laid-Open Patent Publication No. 2011-184235, the temperature of the first combustible gas is high, so the rutile ratio is increased and the photocatalytic activity is low.

In the comparative example 4, the first flammable gas is not circulated at all, and therefore, one of the oxygen of the second flammable gas flows back to the second hollow inner cylinder opening 27, and it is easy to flow, and the first and second hollow inner cylinders are quartz. The tube produces titanium oxide deposits, and the quartz glass is broken due to blockage of the flow path.

On the other hand, in Examples 1 to 12 in which the titanium tetrachloride gas and the first gas G2 were not contained in the first gas G2, the titanium oxide deposits did not occur in the first and second hollow inner cylinder quartz tubes. It is known that it can be produced in a high yield of 95% or more and at least 100 hours in a long time.

In Examples 1 to 4, by changing the flow rate of the first gas G2, the residence time of the first merging gas in the first region B was changed, and the characteristics of the obtained titanium oxide particles were compared.

With respect to 32 milliseconds of Example 1, when the growth was 47 milliseconds (Example 3) and 75 milliseconds (Example 4), the rutile ratio was increased from 4% to 6%, and the photocatalytic activity was somewhat lowered. Conversely, when shortened to 27 milliseconds (Example 2), the rutile ratio decreased somewhat, but the photocatalytic activity decreased somewhat.

In Examples 1 and 5 to 7, the concentration of titanium tetrachloride in the first merging gas was changed by changing the flow rate of titanium tetrachloride, and the characteristics of the obtained titanium oxide particles were compared. With respect to 3.8% of Example 1, the BET value of Example 5 in which the concentration of titanium tetrachloride in the first merging gas was 0.6% was increased, and the photocatalytic activity was somewhat increased. With respect to 3.8% of Example 1, when the concentration of titanium tetrachloride in the first merging gas was 5.9% (Example 6) and 13.6% (Example 7), the BET value was lowered from 14 m ² /g to 9 m. ² / g, the rutile ratio increased from 4% to 8%, and the photocatalytic activity decreased. Thereby, the concentration of titanium tetrachloride in the first merging gas is preferably from 0.1 to 20% by volume, more preferably from 0.5 to 10% by volume, still more preferably from 0.5 to 5% by volume.

In Examples 1 and 8, the preheating temperature of the first gas G2 was changed, and the characteristics of the obtained titanium oxide particles were compared. In Example 1 in which the preheating temperature of the first gas G2 was 1010 ° C and the example 8 was 900 ° C, the rutile ratio was the same as in Example 1, and the photocatalytic activity was relatively high.

In order to obtain high photocatalytic activity from Examples 1 and 8, the preheating temperature of the first gas G2 is preferably in the range of 800 ° C to 1050 ° C, more preferably in the range of 850 ° C to 1050 ° C.

Using Examples 1 and 8 to 10, the preheating temperature of the second gas G3 was changed, and the characteristics of the obtained titanium oxide particles were compared. The preheating temperature of the first gas G2 is 900 ° C, the preheating temperature of the second gas G3 is 1030 ° C, and the preheating temperature of the first gas G2 is 900 ° C and the second gas. In Example 9, in which the preheating temperature of G3 was set to 950 ° C, the rutile ratio was somewhat lowered, but the photocatalytic activity was somewhat lowered. In Example 10 in which the preheating temperature of the second gas G3 was 1100 ° C, the ratio of rutile was lowered as compared with Example 1 at 1030 ° C, and the photocatalytic activity was lowered.

Therefore, the preheating temperature of the second gas G3 is preferably in the range of 900 ° C to 1100 ° C, more preferably in the range of 950 ° C to 1050 ° C.

Using Examples 1, 11, and 12, the temperature of the metal chloride-containing gas G1 was changed, and the characteristics of the obtained titanium oxide particles were compared. With respect to 880 ° C of Example 1, when the temperature was increased to 980 ° C (Example 11), the rutile ratio was increased from 4% to 5%, and the photocatalytic activity was lowered.

Conversely, when the temperature is lowered to 650 ° C, the rutile ratio is reduced from 4% to 3%, and the photocatalytic activity is higher.

Therefore, the preheating temperature of the metal chloride-containing gas G1 is preferably in the range of 600 ° C to 1000 ° C, more preferably in the range of from 600 ° C to 950 ° C, still more preferably in the range of from 800 ° C to 950 ° C.

Using Examples 1, 8, 11, and 12, the temperature of the first merging gas was changed, and the characteristics of the obtained titanium oxide particles were compared.

In the eighth embodiment, the temperature of the first merging gas is lowered by lowering the preheating temperature of the first gas G2 to be lower than that of the first embodiment. Specifically, in Example 1, the temperature of the first merging gas was 979 ° C, and in Example 8, the temperature of the first merging gas was lowered to 895 ° C, but a relatively high photocatalytic activity was obtained.

Embodiment 12 reduces the first combined gas by lowering the preheating temperature of the metal chloride-containing gas G1 to be lower than that of the first embodiment. The temperature. Specifically, in Example 1, the temperature of the first merging gas was 979 ° C, and in Example 12, the temperature of the first merging gas was 925 ° C, but a relatively high photocatalytic activity was obtained.

In the eleventh embodiment, the preheating temperature of the metal chloride-containing gas G1 is raised to be higher than that of the first embodiment to increase the temperature of the first merging gas. In the first embodiment, when the temperature of the first merging gas is 979 ° C, the rutile ratio is 4%, and in the eleventh embodiment, the temperature of the first merging gas is increased to 1003 ° C, and the rutile ratio is also When it rises to 5%, the photocatalytic activity decreases.

Therefore, the temperature of the first merging gas is preferably a temperature range of 800 ° C or more and 1050 ° C or less, more preferably 850 ° C or more and 1000 ° C or less, and still more preferably 900 ° C or more and 1000 ° C or less.

In Examples 1, 9, and 10, the temperature of the second merging gas was changed, and the characteristics of the obtained titanium oxide particles were compared. In the first embodiment, the temperature of the second merging gas was set to 1020 ° C, and in the ninth embodiment, the temperature of the second merging gas was lowered to 939 ° C, but the photocatalytic activity was somewhat lowered.

Further, in the first embodiment, when the temperature of the second merging gas is 1020 ° C, the rutile ratio is 4%, and in the case 10, the temperature of the second merging gas is increased to 1076 ° C, rutile. The proportion rose to 12% and the photocatalytic activity was greatly reduced.

Therefore, the temperature of the second merging gas is preferably a temperature range of 800 ° C or more and 1100 ° C or less, more preferably a temperature range of 800 ° C or more and 1050 ° C or less, and still more preferably 850 ° C or more and 1050 ° C or less.

[Industrial Applicability]

The present invention relates to a method for producing a metal oxide particle and a device for producing the same, and particularly to a method for producing a titanium oxide particle having a high photocatalytic activity of titanium oxide for a long period of time, and having availability in a photocatalyst industry or the like.

1‧‧‧ hollow outer cylinder

1a‧‧‧ upstream side

1b‧‧‧ downstream side

2‧‧‧Insulation material (ceramic fiber)

3‧‧‧Product Recycling Department

3a‧‧‧Exhaust pump

3b‧‧‧Pressure adjustment valve

4‧‧‧1st hollow inner tube

4a‧‧‧ upstream side

4b‧‧‧ downstream end (1st junction location)

5‧‧‧2nd hollow inner tube

5a‧‧‧ upstream side

5b‧‧‧ downstream end (2nd merge point)

6‧‧‧Draining tube

11‧‧‧Reaction tube

15‧‧‧1st catheter

16‧‧‧2nd catheter

24‧‧‧1st hollow inner tube opening

25, 26‧‧‧ annular opening

27‧‧‧2nd hollow inner cylinder opening

28‧‧‧ hollow outer cylinder opening

101‧‧‧Manufacturing device for metal oxide particles

A‧‧‧2nd reaction zone

B‧‧‧District 1

G1‧‧‧Gas containing metal chlorides

G2‧‧‧1st gas

G3‧‧‧2nd gas

X‧‧‧Preheating area

Y‧‧‧Preheating area

Z‧‧‧Preheating area

Claims (14)

A method for producing metal oxide particles, comprising a method for producing a metal oxide particle having a step of: preheating a metal chloride-containing gas after preheating and not containing the metal chloride The first gas after the preheating of the compound is merged at the first joining point, and the second combined gas which is not preheated without the metal chloride is separated from the first combined gas as the first combined gas. The second merging point merges at the second merging point on the downstream side, and as the second merging gas, the gas containing the metal chloride and the first gas do not contain oxygen or water vapor, and the second gas is at least The first gas is merged at the first junction point by the preheating temperature of the first gas, and the temperature of the preheating temperature of the first gas is equal to or higher than the preheating temperature of the gas containing the metal chloride, and the first confluence point is Reheating the preheated gas containing the metal chloride to the second merging point (referred to as the first zone), and setting the preheating temperature of the second gas to the first merging gas It Degrees above the temperature, and the first merged gas confluence by the second merging point on the downstream side, the first reheat merged gas. The method for producing a metal oxide particle according to the first aspect of the invention, wherein the metal chloride is titanium tetrachloride, and the metal oxide particles are titanium oxide particles. The method for producing metal oxide particles according to the second aspect of the invention, wherein the titanium oxide particles are decahedral titanium oxide particles. Metal oxides as claimed in any of claims 1 to 3 In the method for producing particles, the preheating temperature of the gas containing the metal chloride is 600 ° C or more and 1000 ° C or less. The method for producing metal oxide particles according to any one of claims 1 to 3, wherein the temperature of the first merging gas is 800 ° C or more and 1050 ° C or less. The method for producing metal oxide particles according to any one of claims 1 to 3, wherein the temperature of the second merging gas is 800 ° C or more and 1100 ° C or less. The method for producing metal oxide particles according to any one of claims 1 to 3, wherein the preheating temperature of the first gas is 800 ° C or more and 1050 ° C or less. The method for producing metal oxide particles according to any one of claims 1 to 3, wherein the preheating temperature of the second gas is 900 ° C or more and 1100 ° C or less. The method for producing metal oxide particles according to any one of claims 1 to 3, wherein the gas containing the metal chloride contains nitrogen. The method for producing a metal oxide particle according to any one of claims 1 to 3, wherein the first gas contains one or more gases selected from the group consisting of nitrogen gas and argon gas. The method for producing a metal oxide particle according to any one of claims 1 to 3, wherein the second gas contains an oxygen gas and one or more gases selected from the group consisting of nitrogen gas, argon gas and water vapor. Metal oxide particles as claimed in claim 2 or 3 In the production method, the concentration of the titanium tetrachloride contained in the first merging gas is 0.1 to 20% by volume. The method for producing metal oxide particles according to any one of claims 1 to 3, wherein the time during which the first merging gas stays in the first region is 2 to 100 milliseconds. The method for producing metal oxide particles according to any one of claims 1 to 3, wherein the Reynolds number of the second merging gas is 10 to 10,000.