JPH05213606A - Production of lower metal oxide - Google Patents

Abstract

PURPOSE:To make a reaction homogeneous and to easily obtain the high-purity powder of a lower metal oxide by spraying a raw powder consisting of a metal oxide and/or a metal into an incomplete-combustion flame formed with the gaseous hydrocarbons and oxygen and quenching the obtained gas. CONSTITUTION:A gaseous hydrocarbon 44 (acetylene) and gaseous oxygen 46 in less than the complete combustion ratio are mixed in a burner 4. The gaseous mixture is ignited to form an incompletecombustion flame in a reaction vessel 62, the powder 34 consisting of a metal oxide and/or a metal is sprayed into the flame along with a carrier gas 32 to generate the metal vapor in the flame. The metal vapor is allowed to react with the gas generated by the incomplete combustion in a gas phase, and the formed gaseous lower metal oxide is quenched to obtain the powder. The powder is sent to a cyclone 8 and separated from the gas.

Description

Detailed Description of the Invention

[001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for industrially producing a powder of a lower metal oxide, and more particularly to an incomplete combustion obtained by burning a mixed gas of hydrocarbon and oxygen. The present invention relates to a method for producing a metal oxide using a flame. Here, the lower metal oxide in the present invention means, for example, 4
In the case of silicon, which is a group metal, the composition ratio with oxygen is 1:
It refers to SiO, Si2O3, etc. having a composition ratio smaller than 1: 2 with respect to silicon dioxide (SiO2) which is a higher metal oxide of 2, and another example is a Group 6 metal. In the case of tungsten, WO2, W3 having a composition ratio with oxygen smaller than 1: 3 relative to tungsten trioxide which is a higher metal oxide having a composition ratio with oxygen of 1: 3.
It refers to O and the like.

[002]

2. Description of the Related Art The lower oxide of silicon, which is a typical lower metal oxide, has excellent characteristics as a gas barrier film for food packaging, an insulating protective film for electronic parts, a protective film for optical parts and an antireflection film. Therefore, it is an industrially important material as a raw material for vapor deposition of these films.

A known method for synthesizing such a lower metal oxide is to obtain a lower metal oxide by heating a mixture of a metal and a metal oxide at high temperature in a vacuum to cool and condense generated vapor. Has been. However, this method is not suitable for continuous production because it is a batch-wise manufacturing method, and even if it is mass-produced, a large vacuum high-temperature furnace is required, which results in high equipment cost. Have Therefore, there is a demand for the development of a new manufacturing method which can be manufactured continuously without requiring equipment such as a large vacuum high temperature furnace.

As another method for producing a lower metal oxide, it is possible to use a chemical flame, but since the atmosphere of the chemical flame is an oxidizing atmosphere, it is suitable for the synthesis of a high-grade metal oxide. However, it is difficult to apply it to lower metal oxides.

[005] As a method for synthesizing a powder using a chemical flame, for example, "Chemical Engineering" 46,524 as shown in _(1982), H ₂ -O 2 flame and _C X _H Y -O ₂ There is an example of supplying volatile metal halide to a flame to synthesize ultrafine oxide particles. The method using such a chemical flame has many industrial advantages such as a small initial cost for equipment and easy mass production, but the chemical flame is treated only as a high-temperature oxidizing atmosphere. Since a flame in a completely combusted state in which oxygen is mixed with hydrocarbon at a ratio higher than the theoretical mixing ratio is used, only high-grade metal oxide can be synthesized by this method.

Further, Japanese Patent Application Laid-Open No. 60-255602 proposes a method for producing ultrafine oxide particles by charging a metal powder into a burner. In this case, the burner is an auxiliary heat source for promoting the reaction. However, since ultrafine particles are synthesized by a self-combustion reaction of metal powder in an oxygen atmosphere, only high-grade metal oxides can be synthesized.

[0097]

Therefore, an object of the present invention is to use a novel synthetic method applying a chemical flame method to a lower metal oxide, which has been difficult to synthesize by a conventional chemical flame method. Another object of the present invention is to provide a method for producing a lower metal oxide, which is industrially continuous, convenient, and inexpensive to produce.

[0085]

The above-mentioned object is to form an incomplete combustion flame by mixing hydrocarbon gas and oxygen gas in a ratio smaller than the complete combustion ratio and igniting the mixture, and then incomplete combustion flame Is sprayed together with an inert carrier gas, a raw material powder consisting of either a metal oxide powder or a metal powder, or both powders, which easily generate metal vapor by the action of the incomplete combustion flame. A gas and the above metal vapor are subjected to a gas phase reaction to generate a gas of a lower metal oxide, and the gas is rapidly cooled to obtain a powder of the lower metal oxide. To be done.

Preferably, the incomplete combustion flame is formed in the absence of a gas containing oxygen in the surroundings, and the lower metal oxide is transported and recovered together with the combustion exhaust gas discharged from the incomplete combustion flame.

Further, the production method of the present invention is characterized in that the oxygen content of the lower metal oxide is controlled by changing the mixing ratio of the oxygen gas mixed with the hydrocarbon gas.

For example, in the production method of the present invention, the hydrocarbon gas is acetylene gas, and the oxygen gas is mixed at a flow rate of more than 0.95 mol and less than 1.5 mol with respect to 1 mol of acetylene. The raw material powder is silicon dioxide.

[0112]

The gas phase reaction in the incomplete combustion flame in the present invention is
Steam of raw material powder generated by the action of incomplete combustion flame,
Carbon monoxide or carbon radicals generated by incomplete combustion of hydrocarbon gas react at high temperature to form lower metal oxide vapor, and when this lower metal oxide vapor goes out of the flame, it is cooled rapidly. It is condensed to form a lower metal oxide powder.

Further, since the quenching process is performed, a non-stoichiometric composition of lower metal oxide (for example, TiO0.7 or TiO1.
25, etc., which have some of the crystal lattices as vacancies, or those which are unstable at room temperature (eg Si
O) can be synthesized.

Examples of the oxide powder obtained by the production method of the present invention include lower oxides of metals such as silicon, germanium, titanium, molybdenum, tungsten and europium. As these raw materials for production, oxide powders or metal powders of the respective metals can be used. For example, when synthesizing silicon monoxide (SiO), silicon dioxide powder (SiO2) or metallic silicon powder (Si) can be used.

These raw material powders are atomized and blown into the flame so that the temperature thereof is easily raised by the heat of the incomplete combustion flame. Atomization is an operation in which the raw material powder is uniformly dispersed in a carrier gas, and this is performed by a powder feeder having a stirring blade, a table feeder, and a dispersion nozzle inside. The raw material powder finely disentangled by the stirring blade is quantitatively sent little by little to the dispersion nozzle by the table feeder, and is made into a mist state by the carrier gas blown from the dispersion nozzle at high pressure and high speed. The atomized raw material powder is pressure-fed to the burner via a transport pipe and ejected from the central portion of the burner into an incomplete combustion flame. At this time,
If the particle size of the raw material powder is too small, the powders tend to agglomerate with each other to form a large lump, which may cause inconvenience in operation such that the temperature does not rise sufficiently in an incomplete combustion flame or the feed pipe is clogged. On the contrary, if the particle size is too large, the heat capacity is large and the temperature does not rise sufficiently in the flame.
For this reason, the particle size of the raw material powder is restricted, so that it is 3 to 1
It is preferable to adjust to the range of 0 μm.

On the other hand, as the type of carrier gas, since it does not affect the oxygen concentration in the incomplete combustion flame, does not react with metal at high temperatures, has a small heat capacity and does not lower the temperature of the flame, etc. It is preferable to use an inert gas. As the flow rate of the carrier gas increases, it is easier to atomize the powder and facilitate transportation in the rotary pipe, but if the flow rate is too high, the state of the incomplete combustion flame is affected, which is not preferable. The flow rate is preferably adjusted to be equal to or less than the flow rate gas of hydrocarbons supplied to the burner, and more preferably adjusted to 1/2 or less. Further, it is preferable that the total orifice area of the dispersion nozzles is 0.1 mm ² or less so that the atomization and the transportation can be performed with the gas having the smallest flow rate.

The hydrocarbon gas used in the present invention includes methane, ethane, propane, butane, ethylene,
Propylene, acetylene, etc. can be used. Among these, acetylene having a high flame temperature is most preferable. This is for the following reasons. Normally, the temperature of the outer peripheral part of the flame is lower than that of the inner part, so when incomplete combustion, soot is easily generated in this outer part, and the generated soot is mixed in the generated powder. There is a risk of becoming impurities. Therefore, the use of a gas having a high combustion temperature such as acetylene is advantageous because the generation of "soot" is suppressed.

Since the present invention forms an incomplete combustion flame by mixing a hydrocarbon gas and an oxygen gas, the incomplete combustion flame in the present invention is, for example, an example in which acetylene gas is used as the hydrocarbon gas. In the case of complete combustion, the reaction is C2H2 + 2.5O2 → 2CO2 + H2O, and the gas components generated by combustion are carbon dioxide and water vapor, but the mixing ratio of oxygen is small, that is, When the oxygen is insufficient, the combustion gas contains carbon monoxide and hydrogen, and when the mixing ratio decreases to 1, the reaction becomes C2H2 + O2 → 2CO + H2, and the neutral combustion state Becomes Further, when the mixing ratio of oxygen becomes small, carbon radicals will be recognized in the combustion flame, resulting in a reducing combustion state.

Therefore, when acetylene gas is used as the hydrocarbon, incomplete combustion is obtained by making the mixing ratio m of oxygen gas smaller than 2.5 with respect to acetylene 1,
At this time, the components of the combustion gas also change as the value of the mixing ratio m changes, and the atmosphere of the incomplete combustion flame changes from the acidic atmosphere to the neutral and then the reducing atmosphere.

In the above case, the acetylene gas which is preferable as the hydrocarbon gas has been described.
Considering the mixing ratio m of oxygen gas in the case of the hydrocarbon gas represented by XHY, a neutral burning flame similar to the above-mentioned acetylene gas is CXHY + (X / 2) · O2 → X · CO + (Y / 2 ). It is represented by H2. Based on the oxygen mixture ratio (X / 2) of the neutral combustion flame, in the present invention, the oxygen gas mixture ratio m
Is adjusted to a range of 0.95 · (X / 2) <m <1.5 · (X / 2) ... (A).

The value of the mixing ratio m of the oxygen gas is adjusted within the range of the formula (A), as in the case of the acetylene gas of X / 2 = 1. When the atmosphere changes and the mixing ratio m becomes too large, it exhibits a strong oxidizing property, which causes the product to be completely oxidized,
It is unsuitable for the synthesis of lower metal oxides.

On the other hand, if the mixing ratio m of oxygen gas becomes too small, metal carbide may be mixed in the product, or the concentration of the carbon source in the flame may become excessive and "soot" may be precipitated. become. Therefore, the mixing ratio m is preferably adjusted within the range of the above formula (A).

More importantly, since the oxygen concentration in the lower metal oxide changes depending on the value of the mixing ratio m of oxygen gas, in order to obtain a desired oxygen concentration, the oxygen concentration in the range of the above formula (A) is further increased. It is desirable to make fine adjustments.

For example, when producing a lower oxide SiOx of silicon, when the oxygen concentration x is increased, the mixing ratio m is increased,
On the contrary, when lowering the oxygen concentration x, the oxygen concentration x can be freely changed by reducing the mixing ratio m.

In the present invention, since it is necessary to vaporize the raw material powder in the incomplete combustion flame, the temperature of the flame is adjusted to be higher than the vaporization temperature of the raw material powder. Depending on the type of hydrocarbon used and the mixing ratio of oxygen, the calorific value may be so small that the vaporization temperature may not be exceeded. In such a case, it is advisable to perform auxiliary heating with an external heater to raise the temperature of the flame to the vaporization temperature or higher.

In the present invention, the feed amount of the raw material powder fed during the incomplete combustion flame is adjusted by the table feeder in the powder feeder, but if the amount is too large, it will affect the flame temperature and yield. Therefore, considering the type and flow rate of hydrocarbons used, the mixing ratio of oxygen, the heat capacity of the raw material powder, the flow rate of the carrier gas, the amount of heat that goes in and out with the gas phase reaction, the presence or absence of auxiliary heating, The optimum amount is easily determined so that the phase reaction proceeds sufficiently.

In the present invention, the incomplete combustion flame is preferably formed in an oxygen-free atmosphere. When burned in an atmosphere containing oxygen such as air, the flame has a double structure consisting of a non-oxidizing internal flame in the center and an oxidizing external flame that diffuses and mixes with the external air. This is due to the inconvenience that the lower metal oxide formed by the flame is oxidized while passing through the external flame. The oxygen-free atmosphere can be easily created by, for example, a device configuration in which a burner is attached to one end of the reaction vessel which is shielded from the outside air and the gas in the vessel is exhausted from the other end.

The lower metal oxide gas produced by the gas phase reaction in the flame is rapidly cooled and condensed into a powder when it goes out of the flame. This powder is guided to a dust collector such as a cyclone or a bag filter attached to the exhaust side of the reaction vessel together with the combustion exhaust gas, separated from the exhaust gas, and collected as a product.

In other words, the present invention relates to a gas in a hydrocarbon incomplete combustion flame formed in an oxygen-free atmosphere,
This is a method for producing a lower metal oxide of a metal by utilizing a gas phase reaction with vapor of a raw material powder gasified by the heat of a flame, and when a lower oxide of silicon is synthesized from a silicon dioxide powder as a raw material. As an example, powder is synthesized through the following process. First, the raw material silicon dioxide powder is atomized in the powder feeder and blown into the flame together with the carrier gas. The atomized silicon dioxide powder is easily vaporized by the heat and temperature of the flame and immediately reacts with carbon monoxide and carbon radicals in incomplete combustion to form vapor of silicon oxide (SiOx). When the generated silicon oxide vapor goes out of the flame, it is rapidly cooled to form silicon oxide powder. By this quenching action, a lower oxide of silicon that is unstable at room temperature can be obtained. It can be commercialized simply by collecting it with a dust collector.

[030]

EXAMPLES First, an apparatus for producing a lower metal oxide according to the present invention will be described. This manufacturing apparatus includes a powder feeder unit 2 for feeding raw material powder, a burner unit 4 connected to the powder feeder unit 2 and for supplying hydrocarbon gas and oxygen gas, and a burner unit 4 From the reaction container part 6 continuous from
It comprises a cyclone unit 8, a bag filter unit 10 and an exhaust blower unit 12 which are successively connected from the reaction vessel unit 6 for post-treatment. The powder feeder unit 2, burner unit 4, reaction container unit 6, cyclone unit 8, bag filter unit 10 and exhaust blower unit 12 are hermetically connected to each other to form one system.

The powder feeder 2 continuously supplies the hopper 22 for storing the powder raw material, the stirring blade 24 for stirring the powder raw material in the hopper 22, and the stirred powder raw material. It comprises a table feeder 26 and a dispersion nozzle 28 for dispersing the powder raw material. A motor 30 for driving the stirring blade 24 and the turntable feeder 26 is provided outside the hopper 22. And
A carrier gas supply pipe 32 is incorporated in the dispersion nozzle 28, and an inert high-pressure carrier gas, for example, argon gas is supplied to the dispersion nozzle 28 via the carrier gas supply pipe 32. The dispersion nozzle 28 is connected to the raw material powder feeding pipe 34. 2 and 3 show enlarged views of the dispersion nozzle 28. As apparent from FIGS. 2 and 3, the dispersion nozzles 28 are arranged along the periphery of the turntable feeder 26 at a predetermined interval. 2, 12 in the case of illustration, high-pressure carrier gas is jetted from the carrier gas supply pipe 32 in the direction indicated by arrow a in FIG. 2, and as indicated by reference numeral b in FIG.
The raw material powder is atomized.

The other end of the raw material powder transport pipe 34 is connected to the burner unit 4, and the burner unit 4 has a burner main body 42, and one end of the burner main body 42 has the raw material powder transport pipe 3
4, a hydrocarbon supply pipe 44 and an oxygen supply pipe 46 are connected, and a flow controller (not shown) is attached to each of the raw material powder transfer pipe 34, the hydrocarbon supply pipe 44 and the oxygen supply pipe 46. .. On the other hand, the other end of the burner main body 42 serves as a nozzle, which is hermetically connected to the reaction container section 6.

The reaction vessel portion 6 has a cylindrical reaction vessel 62 which is held in the vertical direction, and the end of the burner body 62 on the nozzle side is airtightly incorporated into the upper portion of the reaction vessel 62. And the replacement gas supply port 64 provided concentrically with the opening. In addition, the reaction vessel 62 corresponding to the length of the flame from the burner section 4 during operation
An external heater 66 for auxiliary heating is attached to the outer peripheral portion of the above portion, and a spark discharge type ignition device 68 is also incorporated. The lower part of the reaction vessel 62 is a water-cooled double tube so as to withstand the high heat received from the flame. The reaction container 62 is connected to a transport pipe 68, and a diluting gas jet nozzle 72 for jetting a diluting gas is inserted into the rotary pipe 70 at a position below the reaction container 62.

The other end of the transport pipe 68 is connected to a cyclone section 8 for collecting the synthesized lower metal oxide powder, and this cyclone section 8 is similar to the lower part of the reaction vessel 62 in a water-cooled secondary chamber. It becomes a heavy pipe and doubles as a gas cooler. A bag filter unit 10 for collecting fine powder is connected to a downstream portion of the cyclone via a transportation pipe, and a high pressure blower unit 12 for exhaust is connected to the downstream side of the bag filter unit 10.

Next, the operation of the apparatus for producing a lower metal oxide thus constructed will be described.

First, from the replacement gas supply port 64 to the reaction container 62.
An inert gas such as argon gas is flown into the chamber, at the same time a diluent gas such as air or nitrogen is poured into the transport pipe 70 from the diluent gas supply nozzle 72, and the high pressure blower unit 12 for exhausting the cyclone from the reaction vessel unit 6 is used. The gas in the system up to the part 8 and the bag filter part 10 is exhausted,
As a result, the gas in the system is gradually replaced with the inert gas.

Subsequently, the hydrocarbon gas and the oxygen gas are supplied to the burner section 4 from the hydrocarbon supply piping 44 and the oxygen supply piping 46, respectively, and are premixed inside the burner section 4 and then ejected into the reaction vessel 62. It During operation, the flow rate and mixing ratio of each gas are accurately controlled by the mass flow controller so that they are always kept at preset values. The mixed gas ejected into the reaction container 62 is ignited by the ignition device 68 immediately after the ejection, and an incomplete combustion flame is formed in the reaction container 62. If you need auxiliary heating,
Predetermined electric power is applied to the external heater 66 before the gas is supplied.

Due to the action of this incomplete combustion flame, the reaction vessel 6
The oxygen remaining in 2 is gradually consumed, and after a certain period of time, the inside of the reaction vessel 62 becomes an incomplete atmosphere consisting of the incomplete combustion gas generated from the mixed gas by the ignition and the replacement gas. Can be completely replaced.

The supply of the replacement gas from the replacement gas supply port 64 is continued during operation in order to protect the tube walls of the reaction vessel 62 and the transport tube 70 from heat, and is also supplied from the dilution gas jet nozzle 72. The injection of diluent gas is also continued, which allows
Cyclone part 8 and bag filter part 1 where gas easily accumulates
The incomplete combustion gas is diluted so that an explosion within 0 does not occur. The flow rate is controlled by a flow meter, and the concentration of combustible gas generated by incomplete combustion is adjusted so as to fall outside the explosion range.

After the gas in the reaction vessel 62 is replaced in this manner, the atomized raw material powder is supplied from the powder feeder 2 into the incomplete combustion flame via the raw material powder transport pipe 34. .. In the powder feeder unit 2, after the raw material powder filled in the hopper 22 is loosened by the stirring blades 24 inside, it is quantitatively supplied little by little by the table feeder 26 to the outlet of the dispersion nozzle 28. , Dispersion nozzle 28
The high-pressure and high-speed carrier gas blown out from the powder causes the powder to be very finely dispersed and atomized.

When the atomized raw material powder is blown into the incomplete combustion flame, the raw material powder is vaporized by the heat of the flame and undergoes a gas phase reaction with the gas in the flame to generate a lower oxide vapor, When it goes out, it is rapidly cooled to form low-grade metal oxide powder.

Then, the low-grade metal oxide powder is sent to the cyclone unit 8 together with the gas through the transport pipe 70, where it is separated and collected from the gas. The remaining fine particles that cannot be separated in the cyclone unit 8 are completely separated from the gas in the bag filter unit 12 in the subsequent stage and collected. The separated gas is discharged to the outside of the system through the exhaust high-pressure blower unit 12.

Specific examples of producing a lower metal oxide powder using such an oxide powder producing apparatus will be described below.

(Example 1) An example in which acetylene is used as a hydrocarbon gas to form an incomplete combustion flame and a lower oxide of silicon is synthesized from a silicon dioxide powder as a raw material powder is shown below.

First, argon gas was blown into the reaction vessel 62 from the replacement gas supply port 64 at a flow rate of 50 (flow rate in standard state per minute, liter unit, ie, "Nl / min" hereinafter), On the other hand, air was ejected from the dilution gas ejecting nozzle 72 at a flow rate of 1000 (Nl / min), thereby replacing the gas in the system.

Subsequently, acetylene gas and oxygen gas were supplied to the burner section 4 at flow rates of 20.9 (Nl / min) and 18.8 (Nl / min), respectively, and an incomplete combustion flame was generated in the reaction vessel 62.
Was formed inside. At this time, since the mixing ratio of oxygen gas in the above formula (A) is m = 0.98, in addition to carbon monoxide and hydrogen due to incomplete combustion of acetylene in the flame,
Some carbon radicals are produced and the flame is in a weak reducing state.

The raw material powder silicon dioxide has an average particle size of 6.1 μm.
m of powder and 9 carrier gas of argon (kilogram force per square centimeter, ie kgf / cm
^It was ejected from the dispersion nozzle 28 at a pressure of ² ) and a flow rate of 9 (Nl / min), and was supplied to the burner section 4 at a rate of 3 (g / min).

The flame temperature at this time is 29 according to the heat balance calculation.
It becomes 00 ° C. This temperature is the vaporization temperature of silicon dioxide 29
Since it is slightly lower than 50 ° C., it is necessary to perform auxiliary heating by the external heater 66. Therefore, before forming the flame, the external heater 6 is controlled so that the temperature in the reaction vessel 62 becomes 300 ° C.
The temperature was adjusted by 6.

The produced lower metal oxide powder was separated from the gas in the cyclone section 8 and the bag filter section 10 and collected.

The lower metal oxide powder thus synthesized was evaluated by observation with a transmission electron microscope, measurement of adsorption specific surface area by BET method, X-ray diffraction, EDS analysis and chemical analysis.

FIG. 4 shows an electron micrograph of the obtained lower oxide powder of silicon. From this photograph and the measurement of the adsorption specific surface area, the lower metal oxide powder obtained had a particle size of 50 to 1
It was a fine spherical powder having a particle size of 00 nm and a specific surface area of 80 m ² / g.

FIG. 5 shows an X-ray diffraction diagram of the obtained lower oxide powder of silicon. Clearly from the diffraction pattern of FIG.
It can be seen that the obtained powder has an amorphous structure.

Further, energy dispersive X-ray spectroscopy (ED
From the results of S analysis), the ratio of silicon to oxygen in each powder is 1:
It was found that the obtained lower oxide of silicon was represented by the chemical formula of SiO 2.

Next, the results of chemical analysis of other elements are shown below. For comparison, the measured values of the raw material powder are shown in parentheses. Fe 180ppm (260ppm) Co less than 3ppm (less than 3ppm) Zr less than 1ppm (8ppm) Ni less than 1ppm (2ppm) Cr less than 1ppm (2ppm) Mn less than 1ppm (2ppm) Thus, in the lower oxide of silicon obtained It can be seen that the impurities are less than in the raw material powder and the purity is higher.

(Examples 2 to 4) The mixing ratio m of oxygen gas in Example 1 was 0.98, but in Examples 2 to 4,
Lower mixing oxides of silicon were produced by changing the mixing ratio m to 1.0, 1.2 and 1.4, respectively. The value of oxygen concentration x in the recovered silicon lower oxide SiOx was evaluated by EDS analysis.

FIG. 6 shows the relationship between the value of the mixing ratio m and the oxygen concentration in the lower oxide of silicon. It is apparent from FIG. 6 that the oxygen concentration x in the lower oxide of silicon can be controlled by changing the mixing ratio m, and the oxygen concentration x in the formula SiOx can be increased by increasing the mixing ratio m. Could be increased.

Example 5 An example of synthesizing a germanium lower oxide from a metal germanium powder is shown below.

When metal powder is used as a raw material, the mixing ratio m of oxygen gas is preferably larger than 1, and here, the mixing ratio is 1.1. Further, since the vaporization temperature of the metal germanium was 2830 ° C. and the oxidation of the germanium metal was an exothermic reaction, auxiliary heating by the external heater 66 was not performed. The recovered powder was a fine powder of germanium lower oxide represented by the chemical formula of GeO by EDS analysis.

[059]

As described above, according to the method of the present invention, it is difficult to synthesize by the conventional chemical flame method by causing the vapor phase reaction with the vapor of the raw material powder by the action of the incomplete combustion flame of hydrocarbon. A new synthetic method applying a chemical flame method to a lower metal oxide, which was said to be, has been developed, and as a result, a lower metal oxide can be industrially continuously and simply and inexpensively produced. Can be provided. Compared with the conventional method using a large vacuum furnace, according to the method of the present invention,
The equipment can be extremely simple, and the initial cost can be overwhelmingly reduced.

Further, according to the method of the present invention, a metal oxide powder or a lower metal oxide can be produced from a metal powder as a raw material powder by a gas phase reaction due to an incomplete combustion flame of a hydrocarbon, and the raw material powder is once produced. Since gasification and gas phase reaction are carried out, the reaction proceeds uniformly, and the obtained powder has extremely high purity.

Further, according to the method of the present invention, the oxygen concentration in the oxide powder can be arbitrarily changed by controlling the mixing ratio of oxygen gas.

Furthermore, since the quenching step is performed after the gas phase reaction, a non-stoichiometric composition or a lower metal oxide unstable at room temperature can be synthesized.

[Brief description of drawings]

FIG. 1 is a schematic system diagram showing an apparatus for producing a lower metal oxide according to the present invention.

FIG. 2 is a schematic view schematically showing in an enlarged manner the vicinity of a dispersion nozzle of the powder feeder unit of FIG.

FIG. 3 is a schematic view showing the dispersion nozzle of FIG. 2 from below.

FIG. 4 is an electron micrograph showing a particle structure of a silicon oxide powder obtained according to an example of the present invention.

5 is a graph showing X-ray diffraction of the silicon oxide powder of FIG.

FIG. 6 is a graph showing the relationship between the oxygen gas mixture ratio and the oxygen concentration in the silicon oxide of the present invention.

[Explanation of symbols]

 2 powder supply unit 4 burner unit 6 reaction container unit 8 cyclone unit 10 bag filter unit 12 high pressure blower unit 28 dispersion nozzle 32 carrier gas supply pipe 34 powder transport pipe 44 hydrocarbon supply pipe 46 oxygen supply pipe 72 dilution gas jet nozzle

Claims (4)

[Claims] 1. An incomplete combustion flame is formed by mixing and igniting a hydrocarbon gas and an oxygen gas in a ratio smaller than a complete combustion ratio, and then the action of the incomplete combustion flame is generated in the incomplete combustion flame. A powder of a metal oxide or a metal or a powder of both of them that easily generate metal vapor is sprayed together with an inert carrier gas, and the gas generated by the incomplete combustion flame and the metal vapor are vaporized. A method for producing a lower metal oxide, which comprises reacting to generate a lower metal oxide gas and rapidly cooling the gas to obtain a lower metal oxide powder. 2. The incomplete combustion flame is formed in the absence of a gas containing oxygen in the surroundings, and the lower metal oxide is transported and recovered together with the combustion exhaust gas discharged from the incomplete combustion flame. The method for producing a lower metal oxide according to claim 1, wherein 3. The lower metal oxidation according to claim 1 or 2, wherein the oxygen content of the lower metal oxide is controlled by changing the mixing ratio of the oxygen gas mixed with the hydrocarbon gas. Method of manufacturing things. 4. The hydrocarbon gas is acetylene gas, and the oxygen gas is 0.95 per mol of acetylene.
4. The lower metal oxide according to any one of claims 1 to 3, wherein the raw material powder is mixed with a flow rate of more than 1.5 mol and less than 1.5 mol, and the raw material powder is silicon dioxide. Manufacturing method.