JP7468880B2 - Method for producing metal compounds - Google Patents

Description

The present invention relates to a method for producing metal compounds using mechanochemical reactions.

Conventionally, various methods for producing metal compounds have been developed. For example, silicon oxide (silica: SiO ₂ ), a silicon compound, is synthesized by reacting tetrachlorosilane with hydrogen and oxygen, or by reacting sodium silicate (water glass) with acid, as shown below (Non-Patent Document 1).
_SiCl4 + _2H2 + _O2 → _SiO2 + 4HCl
_Na2O - _mSiO2 +HCl→ _SiO2.nH2O + _NaCl

Silicon hydroxide is produced according to the following formula: Silicon hydroxide (silane containing silanol groups (Si-OH)) is produced by hydrolysis of organochlorosilane and organoalkoxysilane.
_{R2SiCl2 + 2H2O} → _R2Si (OH) ₂ + 2HCl
^{R12Si (} _{OR2 ) 2} + _2H2O → ^R12Si (OH) ₂ + ^2R2OH

Moreover, the alkoxysilane is produced by reacting an organochlorosilane with an alcohol to synthesize an organoalkoxysilane, as shown below.
R ¹ _4-n SiCl _n + nR ² OH → R ¹ _4-n Si(OR ² ) _n + nHCl
(n=1 to 3)

Kunio Ito (ed.), "Silicone Handbook," Nikkan Kogyo Shimbun, September 1990, p32, 49, 288-290

As with the silicon compounds described above, conventional methods for producing metal compounds involve long, complicated synthesis steps and low production efficiency. In addition, it is difficult to obtain highly reactive metal compounds, particularly hydroxides, using conventional methods for producing metal compounds.

The present invention was made in consideration of the above circumstances, and aims to provide a method for producing metal compounds, particularly highly reactive hydroxides, in a simple and inexpensive manner using mechanochemical reactions.

In order to achieve the above object, the method for producing a metal compound according to the present invention comprises the steps of:
(A) metal particles which are silicon (Si ) and (B) a solvent containing alcohol,
(C) using a grinder to grind the metal particles (A) while mixing;
A metal compound (D), which is a metal alkoxide, is produced by a mechanochemical reaction.

Moreover, the (C) pulverizer is
Selected from a ball mill, a bead mill, a rod mill, a jet mill, a SAG mill, a ROM mill, and a rotary stone mill;
This may also be the case.

In addition, an additive (F) that promotes a mechanochemical reaction together with the (A) metal particles and the (B) solvent is added,
(C ) The metal particles (A) are pulverized while being mixed using a pulverizer.
This may also be the case.

Moreover, the (F) additive is copper (Cu).
This may also be the case.

According to the present invention, it is possible to inexpensively and easily produce metal compounds at room temperature through mechanochemical reactions. In particular, it is possible to easily synthesize metal hydroxides, which are highly reactive and lack stability.

FIG. 1 is a conceptual diagram showing the configuration of a planetary ball mill apparatus. FIG. 13 is a conceptual diagram showing the state of milling by rotating a container. 1 is a flowchart showing a flow of a metal compound production process according to a first embodiment of the present invention. 1 is a graph showing an example of NMR of a milled solution. 13A is a graph showing an example of NMR when an additive is added, and FIG. 13B is a graph showing an example of NMR when no additive is added.

The method for producing a metal compound according to an embodiment of the present invention, that is, the method for producing a metal compound (D) by mixing (A) metal particles and (B) a solvent using (C) a grinder, through a mechanochemical reaction, will be described in detail below with reference to the drawings.

(Embodiment 1)
<(A) Metal Particles>
The (A) metal particles are metals that serve as raw materials for producing a target metal compound by a mechanochemical reaction, and are, for example, Group 13 (boron group elements), Group 14 (carbon group elements), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), vanadium (V), magnesium (Mg), zirconium (Zr), tungsten (W), etc. The (A) metal particles are, for example, at least one metal selected from the group consisting of silicon (Si), titanium (Ti), aluminum (Al), chromium (Cr), manganese (Mn), iron (Fe), germanium (Ge) and tin (Sn). The (A) metal particles are preferably silicon, titanium, or aluminum, and more preferably silicon or titanium.

<(B) Solvent>
The (B) solvent is, for example, water, alcohol, or a mixed solvent of water and alcohol. When a mixed solvent of water and alcohol is used, the mixing ratio of water and alcohol is not particularly limited, and is appropriately set depending on the type of (A) metal particles selected, the relationship between the input amount of (A) metal particles and the input amount of (B) solvent, the type of (D) metal compound to be generated, and the like.

As the water, for example, distilled water, seawater, etc. can be used, and the pH of the water is preferably 5 or higher. Note that "seawater" here refers to water containing 3% or more of salt, and in the present invention, it particularly refers to an aqueous solution containing 3% or more of sodium chloride.

The alcohol is selected from the following group of aliphatic hydrocarbon alcohols having 1 to 10 carbon atoms. The alcohol can be used alone or in combination. Representative examples of alcohol include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropanol, butyl alcohol, hexyl alcohol, and octyl alcohol. In view of compatibility with water, reactivity with metals, and hydrolysis and reactivity of alkoxy group-containing metal compounds, alcohols with fewer carbon atoms are preferred, with methyl alcohol and ethyl alcohol being even more preferred.

In addition, in order to control the amount of metal alkoxide produced by the mechanochemical reaction in a water/alcohol mixture, it is preferable that the water content of the alcohol used is 50 ppm or less. More specifically, when using commercially available alcohol, it is preferable to dehydrate the alcohol in advance using a molecular sieve or the like.

Alkaline solutions may also be used as the (B) solvent. Examples of alkaline solutions include aqueous sodium hydroxide solutions, aqueous potassium hydroxide solutions, mixed aqueous solutions of sodium hydroxide and potassium hydroxide, aqueous sodium carbonate solutions, aqueous ammonia solutions, and aqueous sodium chloride solutions. Of these, it is preferable to use aqueous sodium hydroxide solutions, as this inhibits the formation of a passive film on the surfaces of the metal particles and improves the efficiency of the metal compound production reaction.

The alkaline solution concentration is preferably 0.01 to 6 M. Solvent (B) with an alkaline solution concentration in this range increases the solubility of the oxide (e.g., SiO ₂ ) of the metal particles that form the oxide film by means of compound ions, and is therefore considered to improve the rate of production of the metal compound.

<(C) Crusher>
The (C) pulverizer may be any type that pulverizes (A) metal particles, and increases the activity of (A) metal particles and (B) solvent by mechanical energy imparted to the (A) metal particles and (B) solvent to cause a mechanochemical reaction, and its operating principle, scale, and other types are not particularly limited. Examples of the (C) pulverizer include a ball mill, a bead mill, a rod mill, a jet mill, a SAG (Semi-Autogenous Grinding) mill, a ROM (Run Of Mine) mill, and a rotary stone mill. In particular, a planetary ball mill is preferable for producing metal compounds because of its high efficiency in mechanochemical reactions.

<(D) Metal Compound>
The (D) metal compound produced varies depending on the (A) metal particles and (B) solvent, but metal oxides, metal hydroxides, and metal alkoxides can be synthesized. For example, when the (A) metal particles are silicon (Si) and the (B) solvent is water alone, silicon oxide (silica: SiO ₂ ), silicon hydroxide (Si _n (OH) _4-n ), and silicon hydroxide oligomers are produced.

When an alkaline solution, for example, an aqueous solution of sodium hydroxide, is used as the (B) solvent, a silicic acid compound similar to a Na-containing water glass compound is generated. When the (B) solvent is, for example, a methyl alcohol-based system, tetramethoxysilane (Si(OCH ₃ ) ₄ ) is generated. When the (B) solvent is a water/alcohol (for example, methyl alcohol) mixed system, silicon oxide, a mixture of tetramethoxysilane, trimethoxysilanol silane, dimethoxydisilanol silane, trisilanol methoxysilane, a polymer such as a dimer or trimer thereof (for example, the same type of tetramethoxysilane), and a polymer such as a dimer or trimer consisting of two or more types (for example, a dimer or trimer from tetramethoxysilane and dimethoxysilane, and a complex thereof) are generated.

Similarly, when the (A) metal particles are metal particles other than silicon (Si), such as titanium (Ti), aluminum (Al), chromium (Cr), manganese (Mn), iron (Fe), germanium (Ge) and tin (Sn), metal oxides, metal hydroxides and metal alkoxides corresponding to the (A) metal particles used are produced.

Examples of metal oxides include titanium oxide ( _TiO2 , TiO, _Ti2O , _Ti3O , _Ti2O3 ), aluminum oxide ( _{Al2O3 , Al2O} , AlO), chromium oxide (III) ( _Cr2O3 ), chromium oxide ( _II ) (CrO), chromium oxide (IV) ( _CrO2 ), chromium oxide (VI) ( _CrO5 , _CrO3 ), manganese oxide (IV) ( _MnO2 ), manganese oxide (II) ( _MnO ), manganese oxide (III) ( _Mn2O3 ), manganese oxide ( _VI ) ( _MnO3 ), manganese oxide (VII) ( _Mn2O7 ), manganese oxide ( _II , _III ) ( _Mn3O4 ), iron oxide (III) ( _Fe2O The generated iron _{oxides are} iron (II) oxide (FeO), iron (II, III) oxide ( _Fe3O4 ), germanium oxide ( _GeO2 ), and tin oxide ( _SnO2 ). The generated metal hydroxides are Ti(OH) ₂ , Al(OH) ₃ , Mn(OH) ₂ , Fe(OH) ₃ , Fe(OH) ₂ , FeOOH (α, β, γ, δ-type iron oxyhydroxides), Ge(OH) ₂ , and Sn(OH) ₂ . The hydroxide of Cr is chromic _acid ( _H2CrO4 ).

The metal alkoxides that _{are generated} include Ti( _OCH3 ) ₄ , Ti( _Ot - _C4H9 ) ₄ , Ge( _OC2H5 ) ₄ , Sn(On- _C4H9 ) ₄ , and Sn(Ot- _C4H9 ) ₄ . However, these have lower reactivity than the case where _silicon is used as the metal particles (A), and it is easier to synthesize the oxides.

In addition, by using the selected (A) metal particles, a polyacid "M _x O _y " (M is Si, Ti, Al, W, Mo, V, Nb, Zr, etc.) is generated as a (D) metal compound. These (D) metal compounds are used for catalysts, magnetic materials, medicines, etc. In addition, in this reaction, the container 12 and the grinding media 21 may use metals such as Si, Ti, W, Zr, etc., or two or more metals may be used. That is, during the operation of the planetary ball mill device 1, a polyacid may be generated as a (D) metal compound based on the metals scraped from the container 12 and the grinding media 21. In addition, by using magnesium (Mg) as the (A) metal particles, an organometallic compound such as a Grignard reagent, W(CH ₃ ) ₆ , etc. may be generated.

<Metal Compound Manufacturing Method>
Next, a method for producing a metal compound will be described. In this embodiment, a method using a planetary ball mill 1 as a pulverizer (C) will be described as an example. As shown in the conceptual diagram of Fig. 1, the planetary ball mill 1 includes a rotationally driven central shaft 11, a table 13 that rotates integrally with the central shaft 11, and a plurality of containers 12 rotatably supported by the table 13.

As shown in Figures 1 and 2, the container 12 revolves around the central axis 11 in the direction of the arrow a, while rotating around the central axis 12a of the container 12 in the direction of the arrow b. As a result, the (A) metal particles are pulverized by the grinding media 21 in each container 12. At this time, the mechanical energy imparted to the (A) metal particles and the (B) solvent increases the activity of the (A) metal particles and the (B) solvent, causing a mechanochemical reaction to occur and produce a metal compound.

In the manufacturing process of the metal compound according to this embodiment, as shown in the flowchart of FIG. 3, first, the grinding medium 21 is placed in the container 12 (step S11).

The container 12 contains the (A) metal particles to be ground, the (B) solvent, etc., and is, for example, a cylindrical container with a lid. As described above, the container 12 is set in the planetary ball mill apparatus 1 and rotates by the operation of the planetary ball mill apparatus 1. This causes a mechanochemical reaction between the (A) metal particles and the (B) solvent inside the container 12.

The material of the container 12 is not particularly limited and may be, for example, tungsten carbide (WC), stainless steel, zirconia ( _ZrO2 ), etc., but it is preferable to use a material that is harder than the (A) metal particles. The material of the container 12 in this embodiment is tungsten carbide (WC). The capacity of the container 12 is not particularly limited and may be appropriately selected depending on the amount of metal oxide to be produced, the allowable temperature during the reaction, etc.

The grinding medium 21 is contained in the container 12 together with the (A) metal particles and the (B) solvent, and is a medium for grinding the (A) metal particles by the rotation of the planetary ball mill device 1. The shape of the grinding medium 21 is not particularly limited, such as ball-shaped or rod-shaped, and the size is also not particularly limited, but it is preferable that the grinding medium 21 is larger than the (A) metal particles in order to grind the (A) metal particles by applying sufficient mechanical energy to them. The material of the grinding medium 21 is generally the same as the material of the container 12. More specifically, the material of the grinding medium 21 is generally the same as the material of the inside of the container 12 with which the (A) metal particles, (B) solvent, etc. are in contact. The grinding medium 21 in this embodiment is a tungsten carbide ball with a diameter of about 1.6 mm. The weight of the grinding medium 21 put into the container 12 is about 100 g.

Next, (A) metal particles are put into the container 12 (step S12). The (A) metal particles are a metal material that is pulverized in the container 12 and undergoes a mechanochemical reaction. The shape, size, etc. of the (A) metal particles are not particularly limited. The (A) metal particles in this embodiment are silicon (Si) powder (manufactured by Sigma-Aldrich) and have a particle size of approximately 20 μm to 60 μm. The amount of (A) metal particles put into the container 12 is not particularly limited, but is 0.1 g in this embodiment.

Then, the (B) solvent is poured into the container 12 (step S13). As described above, the (B) solvent is water, alcohol, a mixed solvent of water/alcohol, or the like. In this embodiment, methyl alcohol dehydrated by a molecular sieve (static method) is used as the (B) solvent. The amount of the (B) solvent poured into the container 12 is 10 ml. The (A) metal particles and the (B) solvent may be mixed in advance before being poured into the container 12.

After (A) the metal particles and (B) the solvent are added, the container 12 is closed with a lid and sealed. In this embodiment, the inside of the container 12 is adjusted to an argon gas atmosphere before sealing. This makes it possible to prevent the gas present in the container 12 from affecting the mechanochemical reaction.

The sealed container 12 is set in the planetary ball mill 1 as shown in FIG. 1 (step S14). The planetary ball mill 1 used in this embodiment is a planetary ball mill (product name: Premium Line P-7) manufactured by Fritsch GmbH of Germany.

After the container 12 is set in the planetary ball mill apparatus 1, the operation of the planetary ball mill apparatus 1 is started (step S15). By changing the rotation speed of the planetary ball mill, i.e., the rotation speed of the container 12, the acceleration acting on the contents of the container 12 changes. Therefore, by adjusting the mass of the grinding media 21 and the rotation speed of the container 12, it is possible to adjust the amount of mechanical energy applied to the (A) metal particles and control the rate of production of the (D) metal compounds by the mechanochemical reaction.

Specifically, using the rotation radius R (mm) of the planetary ball mill apparatus 1 and the rotation speed N (rpm) of the container 12, the relative centrifugal acceleration G (G) acting on the contents of the container 12 can be calculated by the following formula.
G = 1.118 × R × N ² × 10 ⁻⁶

The rotation radius of the planetary ball mill apparatus 1 according to this embodiment (the distance between the central axis 11 of the planetary ball mill apparatus 1 and the central axis 12a of the container 12) is 70 mm, so for example, when the rotation speed N = 500 rpm, the relative centrifugal acceleration G is approximately 19.6 G. Also, when the rotation speed N = 300 rpm, the relative centrifugal acceleration G is approximately 7.04 G. The rotation speed of the container 12 of the planetary ball mill apparatus 1 according to this embodiment is preferably 100 to 700 rpm. Also, the specific rotation speed of the container 12 in this embodiment is 200 rpm.

The (A) metal particles are milled (crushed) by rotating the container 12. During this process, mechanical energy is imparted to the (A) metal particles and the (B) solvent, increasing their activity and causing a mechanochemical reaction. As a result, a metal compound represented by the following (E) general formula (1) is produced (step S16).
(XO) _a MO _{(b-a) / 2} (1)
(In the formula, M is a metal, X is at least one atom or organic group selected from hydrogen, sodium (Na), potassium (K), and an aliphatic hydrocarbon group having 1 to 6 carbon atoms, a is an integer of 0 to 4, and b is an integer of 3 (when a=0 to 3) or 4 (when a=0 to 4).)

4 shows the results of analyzing the components of the solution milled by the above method using nuclear magnetic resonance (NMR). The solution analyzed by NMR was obtained by centrifuging the milled solution at 15,000 rpm for 30 minutes and then extracting the supernatant. The supernatant solution was analyzed by ^29Si NMR. The conditions of the NMR measurement were: resonance frequency: 119.24 MHz, pulse: 45 deg/5.5 μs, pulse interval: 2 s, number of integrations: 1000, sample tube: Teflon (registered trademark) tube (5 mmφ).

4, a peak of the generated metal compound is detected in the range of −30 to −90 ppm. In this embodiment, the (A) metal particles are silicon (Si), and the generated metal compound is represented by the following general formula (2).
(XO) _a SiO _{(4-a) / 2} (2)
(In the formula, X is at least one atom or organic group selected from hydrogen, sodium (Na), potassium (K), and an aliphatic hydrocarbon group having 1 to 6 carbon atoms, and a is an integer of 0 to 4.)

The silicon compound of general formula (2) is produced with silicon oxide (silica: SiO ₂ ) as the main component. In addition, in a water/alcohol (e.g., methyl alcohol) mixed system, a mixture of silicon oxide, tetramethoxysilane, trimethoxysilanol silane, dimethoxydisilanol silane, and trisilanol methoxysilane is produced. Typically, tetramethoxysilane (Si(OCH ₃ ) ₄ ) is produced. The peaks due to the metal compounds shown in FIG. 4 coincide with the chemical shifts of the above metal compounds, and it is believed that these metal compounds are produced.

As explained in detail above, in this embodiment, (A) metal particles and (B) a solvent are mixed using (C) a grinder, and (D) a metal compound is produced by a mechanochemical reaction, making it possible to inexpensively and easily produce metal compounds at room temperature. In particular, metal hydroxides, which are highly reactive and lack stability, can be easily synthesized.

In this embodiment, the (A) metal particles are silicon, but are not limited to this and may be titanium (Ti), aluminum (Al), chromium (Cr), manganese (Mn), iron (Fe), germanium (Ge), tin (Sn), etc., as described above, and may contain multiple of these metals.

For example, when titanium is used as the (A) metal particles, the generated metal compound is a titanium compound represented by the following general formula (3).
(XO) _a TiO _{(4-a) / 2} (3)
(In the formula, X is at least one atom or organic group selected from hydrogen, sodium (Na), potassium (K), and an aliphatic hydrocarbon group having 1 to 6 carbon atoms, and a is an integer of 0 to 4.)

An example of the titanium compound represented by the general formula (3) is tetramethoxytitanium (Ti( _OCH3 ) ₄ ). (A) When titanium is used as the metal particles, it is believed that oxidation and reduction reactions occur through mechanochemical reactions, and the metal compound according to the present invention is efficiently produced.

(Embodiment 2)
The method for producing a metal compound according to the present embodiment differs from the first embodiment in that (F) an additive is charged into the container 12 together with (A) metal particles and (B) a solvent. The other configurations are the same as those of the first embodiment, and therefore the same reference numerals are used.

The flow of the manufacturing process for the metal compound in this embodiment is the same as the flow chart in Figure 3 for embodiment 1.

The material, size, etc. of the container 12 and the grinding media 21 are the same as those of the first embodiment. Specifically, the material of the container 12 and the grinding media 21 is tungsten carbide (WC). The size of the grinding media 21 is about 1.6 mm in diameter, and the input amount is about 100 g.

The grinding medium 21 is put into the container 12 together with the (A) metal particles. In this embodiment, the (A) metal particles are silicon (Si) powder, and have a particle size of approximately 20 μm to 60 μm. The amount of the (A) metal particles put into the container 12 is not particularly limited, but in this embodiment, it is 0.5 g.

In this embodiment, the (F) additive is put into the container 12 together with the (A) metal particles. The (F) additive is a substance that transfers electric charges between the (A) metal particles and promotes the generation of metal compounds, and is, for example, gold (Au), silver (Ag), platinum (Pt), nickel (Ni), palladium (Pd), chromium (Cr), molybdenum (Mo), niobium (Nb), technetium (Tc), cobalt (Co), etc. The (F) additive in this embodiment is copper (Cu) powder, and has a particle size of approximately 200 μm to 500 μm. The amount of the (F) additive put into the container 12 is not particularly limited, but in this embodiment, it is 0.05 g.

Next, the (B) solvent is poured into the container 12. The (B) solvent is methyl alcohol dehydrated by a molecular sieve, as in the first embodiment. The amount of the (B) solvent poured into the container 12 is 10 ml. The (A) metal particles, the (F) additive, and the (B) solvent may be mixed in advance before being poured into the container 12.

After (A) the metal particles, (B) the solvent, and (F) the additives are added, the container 12 is sealed with a lid and set in the planetary ball mill apparatus 1. After the container 12 is set in the planetary ball mill apparatus 1, the operation of the planetary ball mill apparatus 1 is started. In this embodiment, the rotation speed of the planetary ball mill, i.e., the rotation speed of the container 12, is 300 rpm, and the milling time is 2 hours.

The (A) metal particles are milled (crushed) by the rotation of the container 12. During this process, mechanical energy is imparted to the (A) metal particles and the (B) solvent, increasing their activity and causing a mechanochemical reaction. As a result, a metal compound represented by the following (E) general formula (2) is produced.
(XO) _a SiO _{(4-a) / 2} (2)
(In the formula, X is at least one atom or organic group selected from hydrogen, sodium (Na), potassium (K), and an aliphatic hydrocarbon group having 1 to 6 carbon atoms, and a is an integer of 0 to 4.)

Figure 5(a) shows an example of NMR when milling was performed with copper added as additive (F). The sample used for NMR was the supernatant solution obtained after centrifugation (15,000 rpm for 30 minutes) as in embodiment 1. The NMR conditions were also the same as in embodiment 1. Compared to the NMR results shown in Figure 5(b) for the case where additive (F) was not added, it can be seen that many metal compounds were produced.

As explained in detail above, in this embodiment, (A) metal particles, (B) solvent, and (F) additive are mixed together, and (D) metal compound is produced by a mechanochemical reaction, making it possible to produce metal compounds more efficiently.

This invention allows for various embodiments and modifications without departing from the broad spirit and scope of the invention. Furthermore, the above-described embodiment is intended to explain the invention and does not limit the scope of the invention. In other words, the scope of the invention is indicated by the claims, not the embodiments. Furthermore, various modifications made within the scope of the claims and within the scope of the meaning of the invention equivalent thereto are considered to be within the scope of the invention.

The present invention is suitable for metal compound manufacturing processes for producing various metal compounds. It is particularly suitable for manufacturing processes for highly reactive metal compounds such as hydroxides.

1 Planetary ball mill device, 11 Central shaft, 12 Container, 12a Central shaft, 13 Table, 21 Grinding media

Claims (4)

(A) metal particles which are silicon (Si ) and (B) a solvent containing alcohol,
(C) using a grinder to grind the metal particles (A) while mixing;
Producing a metal compound (D) which is a metal alkoxide by a mechanochemical reaction;
A method for producing a metal compound comprising the steps of: The (C) pulverizer is
Selected from a ball mill, a bead mill, a rod mill, a jet mill, a SAG mill, a ROM mill, and a rotary stone mill;
The method for producing a metal compound according to claim 1 . (F) an additive that promotes a mechanochemical reaction together with the (A) metal particles and the (B) solvent,
(C) The metal particles (A) are pulverized while being mixed using a pulverizer.
The method for producing a metal compound according to claim 1 or 2. The (F) additive is copper (Cu).
The method for producing a metal compound according to claim 3 .