TWI548779B - Method for preparing metal compounds - Google Patents

Description

Method for preparing metal compound

The present invention relates to a process for the preparation of an inorganic material, and more particularly to a process for the preparation of a metal compound forming a plurality of plasma fields.

In the 21st century, plasma is regarded as a synonym for high-tech, from fluorescent tubes, semiconductor processing, ultra-fine processing, or next-generation energy applications. The synthesis of inorganic substances by plasma discharge method is a popular technology in recent years. Because of the high-energy electrons and ions present in the plasma, the added atoms and molecules undergo high-energy collision and conduction, thus affecting the configuration state of the electrons, that is, the atoms and molecules in the plasma field are in an excited state. Therefore, its chemical activity is high, and it will return to the substrate state at a nanosecond to microsecond speed to generate ultraviolet light. Because of the high-energy collision, the particles in the plasma field collide with high-speed motion, resulting in high physical activity of each ion in the plasma field, and the electrons, atoms and ions contained in the plasma field due to high-speed movement. The molecules and the molecules each hold different energies and belong to a non-thermal equilibrium state. The temperature is electron temperature > ion temperature > gas temperature (atomic, molecular temperature). Also due to the collision between a very short number of nanoseconds and a few microseconds, it will be strong in the plasma field. Strong shock wave.

According to the related literature, the synthesis of inorganic materials by the plasma discharge method utilizes the tips of the positive and negative electrodes to generate a discharge at a distance of a millimeter to prepare a metal compound. However, as of now, the plasma discharge method uses the positive and negative electrodes as the loss material. When the plasma discharge reaction continues for a period of time, it is necessary to stop the reaction and replace the loss of the positive and negative electrodes before the reaction can be performed again, resulting in a process failure. Continuously, when applied to mass production, production efficiency is difficult to increase.

Another related literature points out that the synthesis of inorganic materials by plasma discharge method uses direct current, but the required DC voltage is as high as 24kV, which has the lack of energy consumption. On the one hand, it does not meet the environmental protection trend of energy saving and carbon reduction. In terms of production costs have increased significantly.

An object of the present invention is to provide a method for preparing a metal compound which can be continuously carried out under a relatively low voltage condition, which can greatly reduce production cost and increase production efficiency when applied to mass production, and can be energy-saving. Environmental trends in carbon reduction.

Another object of the present invention is to provide a method for producing a metal compound which uses water as an electrolyte, whereby the generation of by-products and contaminants can be reduced, and the environmental protection appeal can be met.

According to one embodiment of the present invention, a method for preparing a metal compound comprises providing a pulsed liquid phase plasma discharge device, providing a plurality of metal particles, and performing a plasma discharge reaction. Pulse liquid plasma discharge device includes The power supply module, the two electrodes and the reaction tank, wherein the power supply module comprises a power supply and a pulse controller, the power supply is electrically connected to the pulse controller, and the two electrodes are electrically connected to the power supply module, and the reaction The inside of the tank contains water as an electrolyte, and the two electrodes are in contact with water in the reaction tank. A plurality of metal granules are added to add the metal particles to the reaction tank. The plasma discharge reaction is performed by a power supply module to provide two electrodes and one pulse of electricity, so that a plurality of plasma fields are formed between the metal particles to obtain a metal compound.

According to the preparation method of the metal compound described above, the material of the two electrodes may be aluminum, and the material of the metal particles may be aluminum, and the metal compound obtained is aluminum hydroxide. The material of the two electrodes may be copper, and the material of the metal particles may be copper, and the metal compound obtained is copper oxide. The material of the two electrodes may be nickel, and the material of the metal particles may be nickel, and the metal compound obtained is nickel oxide.

According to the aforementioned preparation method of the metal compound, the metal particles may have a particle diameter of 0.5 cm to 1.5 cm, the distance between the two electrodes may be 5 cm to 15 cm, and the temperature of the reaction tank may be 5 ° C to 25 ° C.

According to the preparation method of the foregoing metal compound, the voltage supplied by the power supply module can be 1 kV to 4 kV. The duty cycle of the pulsed electric power may be 0.25 to 0.75, and the pulse period of the pulsed electric power may be 20 μs to 100 μs.

110, 120, 130‧ ‧ steps

210‧‧‧Power supply module

211‧‧‧Power supply

212‧‧‧pulse controller

220‧‧‧electrode

230‧‧‧Reaction tank

231‧‧‧ water

240‧‧‧Constant water tank

300‧‧‧ metal particles

1 is a flow chart showing the steps of a method for preparing a metal compound according to an embodiment of the present invention; 2 is a schematic view showing a pulse liquid phase plasma discharge device according to an embodiment of the present invention; and FIG. 3A is an X-Ray Diffractometer (XRD) of the products of Embodiments 1 to 3. FIG. 3B is a field-emission scanning electron microscope (FE-SEM) result chart of the products of Examples 1 to 3; FIG. 4A is a first embodiment, an embodiment 4, and an implementation. XRD results of the product of Example 5; Figure 4B shows the FE-SEM results of the products of Example 1, Example 4 and Example 5; Figure 5A shows the results of XRD of the products of Example 1 and Example 6; Figure FE shows the results of FE-SEM results for the products of Example 1 and Example 6; Figure 6A shows the XRD results of the products of Examples 7 to 9; and Figure 6B shows the FE- of the products of Examples 7 to 9. SEM results map.

Please refer to FIG. 1 , which is a flow chart of the steps of the method for preparing a metal compound according to an embodiment of the present invention. In FIG. 1, the method for preparing a metal compound comprises the steps 110, 120 and 130.

Step 110 is to provide a pulsed liquid phase plasma discharge device. Please refer to FIG. 2, which is a schematic diagram of a pulse liquid phase plasma discharge device according to an embodiment of the present invention. In FIG. 2, the pulse liquid phase plasma discharge device includes a power supply module 210 and two electrodes. 220, reaction tank 230 and constant temperature The power supply module 210 includes a power supply 211 and a pulse controller 212, and the power supply 211 is electrically connected to the pulse controller 212. The power supply module 210 optionally includes a transformer (not shown). The two electrodes 220 are electrically connected to the power supply module 210, and the inside of the reaction tank 230 contains water 231 as an electrolyte, and the two electrodes 220 are in contact with the water 231 in the reaction tank 230. Therefore, when the power supply module 210 is in an open state, a current loop can be formed between the power supply module 210, the two electrodes 220, and the water 231.

The constant temperature water tank 240 is not a necessary member, and its purpose is to maintain the temperature of the reaction tank 230 within a specific range. Therefore, it is possible to evaluate whether or not to use it according to actual needs. Further, the manner of maintaining the temperature of the reaction tank 230 within a specific range is not limited thereto, and the other is not limited thereto. Any manner in which the temperature of the reaction tank 230 can be maintained within a specific range can be used.

Step 120 is to provide a plurality of metal particles 300 which are added with metal particles 300 in the reaction tank 230.

Step 130 is to perform a plasma discharge reaction, which is provided by the power supply module 210 to provide a two-electrode 220-pulse electricity to form a plurality of plasma fields between the metal particles 300 to obtain a metal compound.

Conventional plasma discharge method for synthesizing inorganic materials uses the tips of the positive and negative electrodes to generate a discharge at a distance of millimeters, that is, a plasma field is formed between the positive and negative electrodes, and the positive and negative electrodes participate in the reaction and gradually consume. After the reaction has continued for a while, the reaction needs to be stopped to replace the electrode, resulting in a process that is not continuous. However, the method for preparing the metal compound of the present invention forms a plurality of plasmas between the metal particles 300 by adding metal particles 300 to the reaction tank 230. The field, that is, the reactants participating in the plasma discharge reaction is converted into the metal particles 300, and the electrode 220 is mainly used for the conduction circuit. When the metal particles 300 are consumed to a certain extent, it is only necessary to add the metal particles 300 to the reaction tank 230 again. There is no need to suspend the reaction, which is conducive to the continuous progress of the process. When applied to mass production, the production efficiency will be greatly improved.

The preparation method of the metal compound of the invention uses water 231 as the electrolyte, and is different from the use of other chemicals as the electrolyte. The preparation method of the metal compound of the invention does not need to add other chemicals, can reduce environmental pollution sources and reduce production cost. The preparation method of the metal compound of the invention is not easy to produce by-products and/or contaminants, can meet the environmental protection appeal, and the metal compound formed has the advantages of high purity.

The aforementioned metal compound means a hydroxide, an oxide or other compound of a transition metal, a refractory metal, a noble metal, and a rare earth metal. The aforementioned transition metal is, for example, nickel, copper or titanium, the aforementioned refractory metal such as tungsten or molybdenum, the aforementioned noble metal such as silver or palladium, and the aforementioned rare earth metal such as gallium or indium. The method for producing the metal compound of the present invention can elastically adjust the materials of the electrode 220 and the metal particles 300 to be used depending on the kind of the metal compound. For example, when the material of the two electrodes 220 is aluminum, the material of the metal particles 300 is aluminum, the obtained metal compound is aluminum hydroxide; when the material of the two electrodes 220 is copper, and the material of the metal particles 300 is copper, the obtained The metal compound is copper oxide; when the material of the second electrode 220 is nickel, the material of the metal particles is nickel, and the obtained metal compound is nickel oxide.

The water 231 may be distilled water, deionized water or ultrapure water, and the ultrapure water refers to an electrical impedance value of less than or equal to 18.2 MΩ at 25 ° C. The lower the impurities, the less likely to generate by-products and/or contaminants, and the higher the purity of the resulting metal compound.

The metal particles 300 mean that the metal particles 300 have a small size with respect to the bulk material, and the form of the metal particles 300 is not limited to a granular shape, and may be a powder, a sheet, or the like. The metal particles 300 may have a particle diameter of 0.5 cm to 1.5 cm, thereby facilitating the generation of a plasma field. Further, when the metal particles 300 are non-spherical, the aforementioned "particle diameter" means the longest length of the metal particles 300. For example, when the metal particles 300 are in the form of a sheet, the sheet has three lengths of length, width and thickness, and "particle diameter" Refers to the length of the sheet.

In the preparation method of the foregoing metal compound, the distance between the two electrodes 220 may be 5 cm to 15 cm, and when the distance between the two electrodes 220 is less than 5 cm, the formed plasma field is too small, and when the distance between the two electrodes 220 is greater than 15 cm, it is required to be improved. Voltage and lack of energy consumption. The voltage of the power supply provided by the power supply module 210 can be 1 kV to 4 kV. When the voltage is less than 1 kV, the plasma field cannot be generated. When the voltage is higher than 4 kV, the temperature of the reaction tank 230 is too high and energy is consumed. Compared with the conventional method of synthesizing inorganic materials by using DC power, the DC voltage required for conventional use is as high as 24 kV, and the voltage required by the present invention is only 1 kV to 4 kV, and it is apparent that the present invention can effectively reduce energy loss. The aspect can meet the environmental protection trend of energy saving and carbon reduction, and on the other hand, the production cost can be greatly reduced. The temperature of the reaction tank 230 may be 5 ° C to 25 ° C. When the temperature is lower than 5 ° C, the reaction rate may be too low or the plasma discharge reaction may not proceed. When the temperature is higher than 25 ° C, the product of the plasma discharge reaction may be attached. At the surface of the metal particles 300 or the electrode 220, the yield is lowered and energy loss is caused. According to an embodiment of the invention, when the two electrodes 220 The material is aluminum, and the material of the metal particles 300 is aluminum. The aluminum hydroxide colloid generated by the plasma discharge reaction is likely to adhere to the surface of the metal particle 300 or the surface of the electrode 220 due to excessive temperature.

The duty cycle of the pulsed power provided by the power supply module 210 The duty cycle can be 0.25 to 0.75. When the working period of the pulsed electric power is less than 0.25, the discharge time may be too short to affect the yield. When the working period of the pulsed electric power is greater than 0.75, the particle size of the product may be too large. The pulse period can be 20μs to 100μs. The pulse period can affect the particle size and yield of the metal compound. When the pulse period of the pulse is less than 20μs, the plasma discharge reaction may not occur easily. The pulse period is greater than 100 μs, which may cause the discharge time to be too long to cause the temperature of the reaction tank 230 to be too high.

By adjusting the experimental parameters of the preparation method of the metal compound, for example The distance between the two electrodes 220, the addition amount of the metal particles 300, the operating parameters of the pulse electricity (such as the duty cycle and the pulse period), etc., can prepare metal compounds having different specific surface areas and particle sizes, and can expand the metal compounds. Subsequent applications.

Example <Preparation of Metal Compounds of Examples 1 to 9>

Embodiment 1: First, a pulse liquid phase plasma discharge device is provided. The pulse liquid phase plasma discharge device is as shown in FIG. 1 , wherein the power supply provided by the power supply module 210 is pulsed, and the purity of the second electrode 220 is 99.9. (3N) wt%~99.999 (5N) wt% aluminum rod, water 231 is ultrapure water, the reaction tank 230 is made of glass, and the outside of the reaction tank 230 is fixed to the operating temperature by the constant temperature water tank 240 to make the temperature of the reaction tank 230 Maintaining at 5 ° C to 25 ° C, when the temperature is lower than 5 ° C, the reaction rate is too low, when the temperature is higher than 25 ° C, the resulting aluminum hydroxide colloid solution is likely to adhere to the surface of the two electrodes 220 or the surface of the metal particles 300 And the yield is lowered. Thereafter, a plurality of metal particles 300 are provided to uniformly distribute the metal particles 300 to the bottom of the reaction tank 230. In the present embodiment, the metal particles 300 have a purity of 99.9.0 (2N) wt% to 99.999 (5N) wt%. Tiny aluminum particles, which are in the form of flakes, have an average length of 1.5 cm and an average width of 0.15 cm. The mode of pulse current of Embodiment 1 is to use a bipolar pulse, that is, after one cycle is completed, the potentials of the two electrodes 220 are exchanged. After the voltage of the power supply module 210 is adjusted to 2 kV, the power supply module 210 is turned on to start the plasma discharge reaction. The experimental parameters of Example 1 were as follows: the weight (W) of the minute aluminum particles was 5.4 g, the electrode distance (R) between the aluminum bars was 10 cm, and the duty cycle of the pulse electricity (θ; θ = Ton / (Ton + Toff) ) is 0.75, pulse pulse period (τ; τ = Ton + Toff) is 100 μs, after 8 hours of reaction, the power supply module 210 is turned off, and the aluminum hydroxide colloidal solution in the reaction tank 230 is collected, and then at 80 ° C The temperature is dehydrated and dried for 8 hours to obtain aluminum hydroxide powder. The reaction formula of this example is as follows: (i) H ₂ O → H ⁺ + OH ^- ; (ii) Al → Al ³⁺ ; Al ³⁺ +OH ^- → Al(OH) ₃ ; (iii) 2H ⁺ → H ₂ .

The two aluminum rods were weighed before and after the reaction, and the weight change of the two aluminum rods before and after the reaction was less than 0.05%, indicating that the two aluminum rods were mainly used for conducting electricity. The main source of aluminum ions in the reaction formula (ii) is fine aluminum particles.

Examples 2 to 9: The experimental parameters of Example 1 were changed, and the same conditions as in Example 1 were carried out, and the plasma discharge reaction was carried out to obtain the product aluminum hydroxide.

Thereafter, the product aluminum hydroxide of Example 1 was subjected to elemental semi-quantitative analysis using an X-ray energy dispersive spectrometer (EDS; model Hitachi S4800-I), and the products of Examples 1 to 9 were further used. Aluminum hydroxide was analyzed by XRD, FE-SEM (model Hitachi S4800-I), Dynamic Light Scattering, and Surface Area and Porosity Analyzer (BET).

<EDS Measurement Results of Example 1>

Please refer to Table 2, which is the EDS measurement result of the product of Example 1, including the element type, the weight percentage (wt%) of the element and the atomic percentage (atomic%). As shown in Table 2, the product of Example 1 is aluminum. It is mainly oxygen and the atomic percentage of both is 1 to 3, indicating that the product of Example 1 is aluminum hydroxide without error and the purity of the product is extremely high. (Under the principle of inspection, EDS cannot detect hydrogen, which is described here first.)

<Measurement Results of XRD and FE-SEM of Examples 1 to 9>

Please refer to FIG. 3A and FIG. 3B. FIG. 3A is an XRD result diagram of the products of Examples 1 to 3. FIG. 3B is a FE-SEM result diagram of the products of Examples 1 to 3. (a), (b), and (c) in Fig. 3A correspond to the first embodiment, the second embodiment, and the third embodiment, respectively. As can be seen from Fig. 3A, the products of Examples 1 to 3 were aluminum hydroxide without errors. In addition, the more the amount of tiny aluminum particles is added, the more obvious the characteristic peaks in the XRD results. This phenomenon can be attributed to the addition of small aluminum particles, and the number of plasma fields is also increased, which is beneficial to the improvement. The reaction rate of the plasma discharge reaction and the concentration of the aluminum hydroxide colloid further facilitate the crystallization of aluminum hydroxide during subsequent dehydration drying. (a), (b), and (c) in Fig. 3B correspond to the embodiment 1 and the implementation, respectively. In Example 2 and Example 3, the magnifications are all 100k; (d), (e), and (f) in FIG. 3B correspond to Embodiment 1, Embodiment 2, and Embodiment 3, respectively, and the magnifications are all 10k. It can be seen from Fig. 3B that when the amount of the added aluminum particles is increased, the agglomeration phenomenon is less, which is favorable for the formation of particles; on the contrary, when the amount of the minute aluminum particles is less, the number of the plasma fields is less, and the aluminum hydroxide colloid is The concentration is also reduced, which is not conducive to subsequent crystallization.

Please refer to FIG. 4A and FIG. 4B. FIG. 4A is an XRD result diagram of the products of Example 1, Example 4 and Example 5, and FIG. 4B is an FE- of the products of Example 1, Example 4 and Example 5. SEM results map. (a), (b), and (c) in Fig. 4A correspond to the fourth embodiment, the fifth embodiment, and the first embodiment, respectively. As can be seen from Fig. 4A, the products of Example 1, Example 4 and Example 5 were aluminum hydroxide without errors. In addition, the higher the θ, the more obvious the characteristic peak in the XRD result graph. This phenomenon can be attributed to the fact that the higher the θ, the longer the reaction time of the small aluminum particles, and the longer the duration of the plasma field is, which is beneficial to The concentration of the aluminum hydroxide colloid is increased, which in turn facilitates subsequent crystallization. (a), (b), and (c) in Fig. 4B correspond to the fourth embodiment, the fifth embodiment, and the first embodiment, respectively, and the magnifications are all 100k; (d), (e), (b) in Fig. 4B. f) Corresponding to Example 4, Example 5, and Example 1, respectively, the magnifications are all 10k. As can be seen from Fig. 4B, the agglomeration phenomenon of Example 1 is the slightest, and the higher the θ is, the higher the concentration of the aluminum hydroxide colloid is favored, which is advantageous for subsequent crystallization.

Please refer to FIG. 5A and FIG. 5B. FIG. 5A is an XRD result diagram of the products of Example 1 and Example 6, and FIG. 5B is a FE-SEM result diagram of the products of Example 1 and Example 6. (a) and (b) in Fig. 5A correspond to Example 6 and Example 1, respectively. As can be seen from Figure 5A, Example 1 and implementation The product of Example 6 was aluminum hydroxide without errors. In addition, when τ becomes high, the characteristic peaks in the XRD result graph do not change much. (a) and (b) in Fig. 5B correspond to the sixth embodiment and the first embodiment, respectively, and the magnifications are all 100k; (c) and (d) in the fifth embodiment correspond to the sixth embodiment and the first embodiment, respectively. The magnification is 10k. It can be seen from Fig. 5B that when τ is small, the particle size is also small, which can be attributed to the smaller the τ, the shorter the sustained discharge time, the decrease of the concentration of the aluminum hydroxide colloid, and the decrease of the effective collision frequency. Particles.

Please refer to FIGS. 6A and 6B. FIG. 6A is an XRD result diagram of the products of Examples 7 to 9. FIG. 6B is a FE-SEM result diagram of the products of Examples 7 to 9. (a), (b), and (c) in Fig. 6A correspond to Embodiment 7, Example 8, and Example 9, respectively. As can be seen from Fig. 6A, the products of Examples 7 to 9 were aluminum hydroxide without errors. In addition, when R is larger, the characteristic peaks in the XRD result graph are more obvious. This phenomenon can be attributed to the fact that the larger the R, the larger the number of plasma fields between the two electrodes is, which is beneficial to increase the concentration and collision of the aluminum hydroxide colloid. The frequency, which in turn facilitates subsequent crystallization. (a), (b), and (c) in Fig. 6B correspond to Example 9, Example 8, and Example 7, respectively, and the magnifications are all 100k; (d), (e), (b) in Fig. 6B f) Corresponding to Example 9, Example 8, and Example 7, respectively, the magnifications are all 10k. It can be seen from Fig. 6B that when R is larger, the particle size of aluminum hydroxide is larger, and the agglomeration phenomenon is more slight. This phenomenon can be attributed to the fact that when R is larger, the number of plasma fields between the two electrodes is also increased, which is advantageous. The concentration of the aluminum hydroxide colloid is increased, which in turn facilitates subsequent crystallization.

<Measurement Results of Particle Diameter and Specific Surface Area of Examples 1 to 9>

Please refer to Table 3 for the particle size analysis and specific surface area measurement results of the metal compounds of Examples 1 to 9.

It can be seen from Table 3 that the preparation method of the metal compound of the present invention can be prepared by adjusting experimental parameters, such as the distance of the two electrodes, the amount of metal particles added, the operating parameters of the pulsed electricity, etc., to have different particle sizes and ratios. A metal compound of surface area that expands the subsequent application of the metal compound.

In summary, the method for preparing the metal compound of the present invention has the following advantages: (1) adding metal particles to the reaction tank, so that the plasma discharge reaction can be continuously performed, which is advantageous for improving production efficiency. (2) Using water as the electrolyte can reduce cost and pollution and increase the purity of the resulting metal compound. (3) The materials of the electrodes and metal particles can be replaced to form different metal compounds, and the application range is wide. (4) The experimental parameters can be adjusted according to actual needs to prepare metal compounds with different specific surface areas and particle sizes, which can expand metallization Subsequent application of the object. (5) The pulse discharge is used for the plasma discharge reaction, and the required voltage is low (about one-fourth to one-sixth of the direct current), which can effectively reduce the energy loss, and on the other hand, it can meet the energy-saving and carbon-reduction The environmental trend, on the other hand, has greatly reduced production costs.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and the present invention can be modified and modified without departing from the spirit and scope of the present invention. The scope is subject to the definition of the scope of the patent application attached.

110‧‧‧Steps

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130‧‧‧Steps

Claims (6)

A method for preparing a metal compound, comprising: providing a pulse liquid phase plasma discharge device, comprising: a power supply module, comprising a power supply and a pulse controller, wherein the power supply is electrically connected to the pulse controller a second electrode electrically connected to the power supply module; and a reaction tank containing water as an electrolyte, and the two electrodes are in contact with the water; and a plurality of metal particles are provided, and the metal particles are added to the reaction And performing a plasma discharge reaction, wherein the two-electrode-pulse electricity is provided by the power supply module to form a plurality of plasma fields between the metal particles to obtain a metal compound; wherein the metal The particle size of the particles is from 0.5 cm to 1.5 cm, the temperature of the reaction tank is from 5 ° C to 25 ° C, the duty cycle of the pulsed electric power is 0.25 to 0.75, and the pulse period of the pulse electric current is 20 μs. Up to 100μs. The method for preparing a metal compound according to claim 1, wherein the material of the two electrodes is aluminum, the material of the metal particles is aluminum, and the metal compound obtained is aluminum hydroxide. The method for preparing a metal compound according to claim 1, wherein the two electrodes are made of copper, and the metal particles are made of copper. The metal compound is copper oxide. The method for preparing a metal compound according to claim 1, wherein the two electrodes are made of nickel, and the metal particles are made of nickel, and the metal compound obtained is nickel oxide. The method for producing a metal compound according to claim 1, wherein the distance between the two electrodes is 5 cm to 15 cm. The method for producing a metal compound according to claim 1, wherein the pulse electric voltage is from 1 kV to 4 kV.