A Pt catalyst and its preparation method

Abstract

This invention discloses a method for preparing a Pt catalyst, comprising: first mixing porous silica with dopamine, ultrasonicating and then soaking, then adding Tris-HCl to react and obtain a precursor; then loading Pt onto the precursor using chloroplatinic acid to obtain the Pt catalyst. The invention uses dopamine to modify porous silica, obtaining a precursor with a large number of hydroxyl (-OH) groups on its surface, which facilitates coordination during subsequent Pt loading, increases the Pt content in the catalyst, and thus improves the catalytic activity of the catalyst.

Description

Technical Field

[0001] This invention belongs to the field of catalyst materials technology, specifically relating to a Pt catalyst and its preparation method. Background Technology

[0002] Organosilicon materials are a new type of environmentally friendly material with rich functions and excellent performance. They possess good electrical insulation properties, low viscosity coefficient, resistance to high and low temperatures, aging resistance, flame retardancy, and hydrophobicity and moisture resistance, thus being widely used in many fields such as clean energy, infrastructure, medical and health care, and daily consumer goods. Hydrosilylation is one of the most important industrial methods for synthesizing organosilicon materials such as silicone oil, silicone rubber, silicone resin, and silane coupling agents. This reaction refers to the addition reaction between compounds containing Si-H bonds and compounds containing unsaturated bonds (such as C=C, C=O) under specific conditions, producing compounds containing Si-C. These compounds possess both inorganic and organic groups, thus combining the excellent properties of both inorganic and organic compounds.

[0003] Early catalytic hydrosilylation reactions primarily employed physical methods such as ultraviolet light, gamma rays, high temperature, and high pressure. For example, the hydrosilylation reaction of acetylene and dichloromethylsilane, catalyzed by thermal condensation under high temperature and pressure, resulted in low conversion rates and demanding, difficult-to-control reaction conditions. Furthermore, this method suffered from low selectivity and the generation of side reactions, making it unsuitable for large-scale industrial production. Later, researchers discovered that introducing transition metals into the hydrosilylation reaction could further improve the conversion rate, such as Pt, Rh, Ru, Sc, and Ni. This method offers advantages such as milder reaction conditions, higher yields, and better product selectivity. Therefore, the research and development of hydrosilylation catalysts has become a hot topic in the organosilicon industry. Pt catalysts, due to their higher catalytic activity and product selectivity, have become the most widely studied and industrially used transition metal catalysts. However, traditional Pt catalysts suffer from problems such as easy deactivation and low reusability. Therefore, how to ensure higher catalytic activity in Pt catalysts while reducing industrial costs is a key focus for researchers.

[0004] To date, Pt catalysts for hydrosilylation reactions are mainly classified into two categories: homogeneous Pt catalysts and heterogeneous Pt catalysts. Both types of catalysts exhibit high catalytic activity and good catalytic performance for most silanes, alkenes, and alkynes. However, they suffer from drawbacks such as producing numerous hydrogenation products and poor selectivity for certain reactive olefins and olefin-like substances. Furthermore, homogeneous catalysts cannot be recycled, significantly increasing their cost. Therefore, these catalysts have been modified. Currently reported modification methods primarily involve immobilizing platinum on porous supports to form heterogeneous catalysts, which are easily separated from the reaction products. Porous silica is an excellent support, possessing advantages such as high mechanical strength, large specific surface area, easily tunable pore size, narrow pore size distribution, and good chemical and thermal stability. However, due to the low platinum loading, the catalyst fabrication process is relatively complex. Therefore, it is necessary to investigate simple methods for preparing solid-phase low-platinum catalysts with high activity and stability. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a Pt catalyst with porous silica as a support and dopamine as a modifier, and a method for preparing the same, in order to simplify the manufacturing process and improve the activity and stability of solid-phase low-platinum catalysts.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The present invention provides a method for preparing a Pt catalyst, comprising the following steps:

[0008] S1. Porous silica and dopamine are added to the first solvent, ultrasonically treated, and then sealed and soaked to obtain the first solution; Tris-HCl is added to the second solvent, and the pH of the solution is adjusted to 8.5-8.6 with ammonia / sodium hydroxide solution. The solution is mixed with the first solution and reacted at 25-35℃ for 24-48 hours. After the reaction is completed, the solid and liquid are separated, and the obtained solid is washed and dried to obtain the precursor.

[0009] S2. Add the precursor and NaHCO3 to anhydrous ethanol, heat to 60-70°C under an oxygen-free atmosphere, and start adding chloroplatinic acid / ethanol solution dropwise. After the addition is complete, continue the reaction for 5-10 hours. After the reaction is complete, separate the solid and liquid, wash and dry the obtained solid to obtain the Pt catalyst.

[0010] Preferably, in step S1, the mass ratio of porous silica to dopamine is 3 to 6:1.

[0011] Preferably, in step S1, the first solvent is at least one of ethanol, methanol, benzene, and toluene, and the mass-to-volume ratio of the porous silica to the first solvent is 0.1 to 0.3 g / mL.

[0012] Preferably, in step S1, the second solvent is at least one of methanol and toluene, and the mass-volume ratio of Tris-HCl to the second solvent is 0.0011 to 0.0026 g / mL.

[0013] Preferably, in step S1, the volume ratio of the first solvent to the second solvent is 1:4 to 7.

[0014] Preferably, in step S1, the ultrasonic treatment time is 10 to 20 minutes; and the sealed soaking time is 0.5 to 2 hours.

[0015] Preferably, in step S2, the mass ratio of the precursor to the NaHCO3 is 10:1 to 3, the mass-volume ratio of the precursor to the anhydrous ethanol is 40 to 60 g / mL, and the mass ratio of the chloroplatinic acid to the precursor is 10:1 to 3.

[0016] Preferably, in step S2, the concentration of the chloroplatinic acid / ethanol solution is 10-15 mg / mL, and the dropping rate is 3-10 mL / h.

[0017] Preferably, the stirring speed is 250-350 r / min.

[0018] Preferably, the washing process involves alternating between ethanol and water three times.

[0019] The present invention also provides a Pt catalyst prepared by the above preparation method.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] This invention utilizes a grafting modification method, employing dopamine to modify porous silica, thereby increasing the number of hydroxyl groups (-OH) on its surface to coordinate with Pt, resulting in a heterogeneous Pt catalyst from porous silica. This process is simple, uses readily available and inexpensive supports, and achieves a high Pt loading rate. The catalyst exhibits high catalytic efficiency and recyclability, is easily recovered, significantly reducing costs and facilitating industrialization. Attached Figure Description

[0022] Figure 1 The FT-IR spectra of the mSiO2-PDA precursor, mSiO2-PDA-Pt catalyst, and mSiO2 prepared in Example 1 are shown.

[0023] Figure 2 The TG spectra of the mSiO2-PDA precursor, mSiO2-PDA-Pt catalyst, and mSiO2 prepared in Example 1 are shown.

[0024] Figure 3XPS full spectrum of pure mSiO2 and mSiO2-PDA precursor prepared in Example 1.

[0025] Figure 4 The C1s peak fitting spectrum of the mSiO2-PDA precursor prepared in Example 1 is shown.

[0026] Figure 5 The N1s peak fitting spectrum of the mSiO2-PDA precursor prepared in Example 1 is shown.

[0027] Figure 6 XPS full spectra of pure mSiO2, the mSiO2-PDA precursor prepared in Example 1, and the mSiO2-PDA-Pt catalyst.

[0028] Figure 7 The C1s peak fitting spectrum of the mSiO2-PDA-Pt catalyst prepared in Example 1 is shown.

[0029] Figure 8 The N1s peak fitting spectrum of the mSiO2-PDA-Pt catalyst prepared in Example 1 is shown.

[0030] Figure 9 The Pt 4f peak fitting spectrum of the mSiO2-PDA-Pt catalyst prepared in Example 1.

[0031] Figure 10 The product obtained from the cyclic catalytic utilization of the mSiO2-PDA-Pt catalyst prepared in Example 1. 1 H NMR spectrum. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. In the embodiments of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; unless specifically specified, the technical means used are all conventional means well known to those skilled in the art.

[0033] The porous silica particles used in this embodiment of the invention have a particle size of 1–3 cm, a pore size of 8–30 nm, and a specific surface area of ​​140.68–222.3 m². 2 / g.

[0034] Example 1

[0035] The preparation steps of the Pt catalyst in this embodiment are as follows:

[0036] (1) Take 1g of porous silica (mSiO2) and 0.33g of dopamine and add them to 10mL of toluene. Seal and sonicate for 15min. After sonication, soak for 1h. Take 30mL of methanol and 0.0788g of Tris-HCl and add ammonia / sodium hydroxide solution to adjust the pH to 8.5. Mix the two solutions and place them in an oil bath. Stir magnetically at 160r / min at 30℃ for 24h. After the reaction, separate the solid and liquid. Wash the obtained solid with ethanol and water three times alternately and dry it in an oven at 60℃ for 24h to obtain mSiO2-PDA precursor.

[0037] (2) Take 1g of mSiO2-PDA precursor and put it into a three-necked flask. Add 40mL of anhydrous ethanol and 0.3g of NaHCO3. Place it in an oil bath at 70℃ and stir magnetically at 160r / min. Reflux the mixture and purge with nitrogen to create an oxygen-free environment. When the temperature inside the three-necked flask reaches 65℃, start adding 20mL of chloroplatinic acid solution with a concentration of 5mg / mL at a dropping rate of 8mL / h. After the addition is complete, continue the reaction for 18h. After the reaction is complete, separate the solid and liquid. Wash the obtained solid three times with ethanol and water alternately and dry it in a 60℃ oven for 24h to obtain the mSiO2-PDA-Pt catalyst.

[0038] Example 2

[0039] The difference between the preparation steps of the Pt catalyst in this embodiment and those in Example 1 is that the sealing and ultrasonic treatment time in step (1) is 20 min.

[0040] Example 3

[0041] The difference between the preparation steps of the Pt catalyst in this embodiment and those in Example 1 is that the sealing and ultrasonic treatment time in step (1) is 10 min, and the amount of methanol used in the Tris-HCl solution is 50 mL.

[0042] Example 4

[0043] The difference between the preparation steps of the Pt catalyst in this embodiment and those in Example 1 is that the amount of methanol used in the Tris-HCl solution in step (1) is 50 mL.

[0044] Example 5

[0045] The difference between the preparation steps of the Pt catalyst in this embodiment and those in Example 1 is that the sealing and ultrasonic treatment time in step (1) is 10 min, and the amount of methanol used in the Tris-HCl solution is 70 mL.

[0046] Example 6

[0047] The difference between the preparation steps of the Pt catalyst in this embodiment and those in Example 1 is that the sealing and ultrasonic treatment time in step (1) is 20 min, and the amount of methanol used in the Tris-HCl solution is 70 mL.

[0048] Example 7

[0049] The difference between the preparation steps of the Pt catalyst in this embodiment and those in Example 1 is that the sealing and ultrasonic treatment time in step (1) is 10 min and the magnetic stirring speed is 250 r / min.

[0050] Example 8

[0051] The difference between the preparation steps of the Pt catalyst in this embodiment and those in Example 1 is that the sealing and ultrasonic treatment time in step (1) is 20 min and the magnetic stirring speed is 250 r / min.

[0052] Example 9

[0053] The difference between the preparation steps of the Pt catalyst in this embodiment and those in Example 1 is that in step (1), the amount of methanol used in the Tris-HCl solution is 70 mL and the magnetic stirring speed is 250 r / min.

[0054] Example 10

[0055] The difference between the preparation steps of the Pt catalyst in this embodiment and those in Example 1 is that the sealing and ultrasonic treatment time in step (1) is 20 min, the amount of methanol in the Tris-HCl solution is 50 mL, and the magnetic stirring speed is 250 r / min.

[0056] Example 11

[0057] The difference between the preparation steps of the Pt catalyst in this embodiment and those in Example 1 is that the sealing and ultrasonic treatment time in step (1) is 10 min, the amount of methanol used in the Tris-HCl solution is 70 mL, and the magnetic stirring speed is 250 r / min.

[0058] Example 12

[0059] The difference between the preparation steps of the Pt catalyst in this embodiment and those in Example 1 is that in step (1), the amount of methanol used in the Tris-HCl solution is 50 mL and the magnetic stirring speed is 250 r / min.

[0060] The mSiO2-PDA precursor and mSiO2-PDA-Pt catalyst prepared in Examples 1 to 12 were tested.

[0061] Figure 1The FT-IR spectra of the mSiO2-PDA precursor, mSiO2-PDA-Pt catalyst, and mSiO2 prepared in Example 1 are shown. The data were normalized after testing. (Figure 1106 cm⁻¹) -1 and 473cm -1 These are the absorption peaks for the Si-O-Si stretching vibration and bending vibration, respectively, at 802 cm⁻¹. -1 The left and right sides are absorption peaks of Si-O symmetric stretching vibration. All three peaks are present in the modified sample, indicating that silicon dioxide is present in the modified sample and that the structure of silicon dioxide is not destroyed during the modification process. Figure 1 3443cm -1 and 1630cm -1 The absorption peak at position is due to the stretching and bending vibrations of -OH. This absorption peak is present in all three samples, but its intensity is the highest in the mSiO2-PDA precursor, decreases in the mSiO2-PDA-Pt sample, and is the lowest in the mSiO2 sample. This is because after modifying mSiO2 with PDA, the presence of a large number of -OH atoms in PDA increases the intensity of the absorption peak, indicating that the PDA encapsulation modification was successful. However, when Pt is loaded onto the mSiO2-PDA precursor, Pt atoms coordinate with the -OH atoms on the PDA surface, resulting in a decrease in the intensity of the absorption peak. Since the number of Pt atoms participating in the coordination is insufficient, the -OH peak on the PDA surface cannot be completely consumed. Therefore, the intensity of the -OH absorption peak in the mSiO2-PDA-Pt catalyst sample is still higher than that in the mSiO2 sample. Figure 1 1504cm -1 and 1453cm -1 The peak at this point represents the stretching vibration peak of the benzene ring skeleton C=C unique to PDA. This peak is not present in the mSiO2 sample but appears in the mSiO2-PDA and mSiO2-PDA-Pt samples, indicating that PDA has been successfully coated onto the porous silica matrix.

[0062] Figure 2The figures show the TG spectra of the mSiO2-PDA precursor, mSiO2-PDA-Pt catalyst, and mSiO2 prepared in Example 1. The dehydration of the three samples can be roughly divided into two stages: the first stage is from 0 to 150°C, and the second stage is from 150 to 800°C. In the first stage, all samples experienced mass loss, mainly due to water adsorbed by SiO2. However, comparing the curves of mSiO2, mSiO2-PDA, and mSiO2-PDA-Pt shows that mSiO2 experienced the smallest mass loss, while mSiO2-PDA experienced the largest. This is because dopamine modification introduces more hydrophilic groups onto the silica surface, such as an increase in -OH content, leading to greater water adsorption from the air by mSiO2-PDA and thus more severe mass loss. In the second stage, mSiO2 and mSiO2-PDA showed no significant mass loss, while mSiO2-PDA-Pt experienced a significant mass loss, which may be due to the loss of some Pt. When the temperature reaches 800℃, the residual weights of mSiO2 and mSiO2-PDA are 96.04% and 93.31%, respectively. The greater mass loss of mSiO2-PDA is likely due to a small amount of PDA decomposition after heating. The mass loss of both samples is not significant between 0 and 800℃, indicating that mSiO2 and mSiO2-PDA have good thermal stability and can be used as catalyst supports and for modifying silica. The residual weight of SiO2-PDA-Pt is 89.46%, with a mass loss of 10.54%, which is more significant than the mass loss of mSiO2. However, the overall mass remains relatively stable. The more significant mass loss compared to mSiO2-PDA may be due to the loss of some platinum. However, most hydrosilylation reactions have low melting and boiling points, and the reaction is exothermic but the heat dissipation is relatively rapid. Therefore, this catalyst and support can stably exert catalytic efficiency in environments below 200℃ without easily causing Pt to fall off.

[0063] Table 1 shows the ICP-OES test results of the N element content in the mSiO2-PDA precursor and the Pt element content in the mSiO2-PDA-Pt catalyst prepared in Examples 1 to 12.

[0064] Table 1

[0065] Example Nitrogen content (%) Pt element content (%) Example 1 0.56 1.4942 Example 2 0.75 1.3335 Example 3 0.9 0.4680 Example 4 0.31 0.7181 Example 5 0.64 0.6173 Example 6 0.72 0.5931 Example 7 0.54 0.8878 Example 8 0.49 0.6925 Example 9 0.26 0.7605 Example 10 0.17 0.7901 Example 11 0.12 0.5137 Example 12 0.11 0.4713

[0066] As shown in Table 1, when the ultrasonic time in step 1 was 15 min, the solvent volume in the Tris-HCl solution was 60 ml, and the stirring speed was 160 r / min, the nitrogen content in the sample was significantly higher than that in other samples. Since pure silica does not contain nitrogen, and this element is unique to dopamine, the nitrogen content in the sample can indirectly reflect the dopamine encapsulation amount. When the ultrasonic time in step 1 was 15 min, the solvent volume was 40 ml, and the stirring speed was 160 r / min, the platinum content of the prepared catalyst was significantly higher than that of the catalyst prepared under other conditions. This may be because too short an ultrasonic time cannot help dopamine molecules enter the porous silica, while too long an ultrasonic time may damage the structure of the porous silica, preventing platinum atoms from entering the porous silica during platinum loading, thus reducing the platinum content. Excessive solvent volume results in too low a dopamine concentration, leading to a greater tendency for dopamine molecules to self-polymerize, resulting in a low -OH content during platinum loading, which cannot pair with more platinum atoms.

[0067] Figure 3 XPS full spectrum of pure mSiO2 and the mSiO2-PDA precursor prepared in Example 1. Figure 4 The C1s peak fitting spectrum of the mSiO2-PDA precursor is shown. Figure 5 The image shows the N1s peak fitting spectrum of the mSiO2-PDA precursor. Binding energy peaks for O1s, C1s, N1s, and Si2p appear in the full spectrum of the mSiO2-PDA precursor sample. The appearance of the N1s binding energy peak is due to the introduction of N-containing groups after SiO2 modification of PDA, resulting in a signal peak for N elements, further confirming that SiO2 is modified by PDA. All XPS peak fitting spectra use a C1s binding energy of 284.80 eV as the charge correction standard. In the C1s peak fitting spectrum, the absorption peak near 284 eV is considered to be the C atom in the C-C bond, and the absorption peak near 285 eV is considered to be the C atom in the CN bond; in the N1s peak fitting spectrum, the absorption peak near 399 eV is considered to be the N atom in the CN bond, and the absorption peak near 400 eV is considered to be the N atom in the NH bond.

[0068] Figure 6 XPS full spectra of pure mSiO2, the mSiO2-PDA precursor prepared in Example 1, and the mSiO2-PDA-Pt catalyst. Figure 7 The image shows the C1s peak fitting spectrum of the mSiO2-PDA-Pt catalyst. Figure 8 The N1s peak fitting spectrum of the mSiO2-PDA-Pt catalyst is shown. Figure 9The image shows the fitted spectrum of the Pt 4f peak for the mSiO2-PDA-Pt catalyst. Binding energy peaks for O1s, C 1s, N 1s, Si 2p, and Pt 4f appear in the full spectrum of the mSiO2-PDA-Pt catalyst sample. The fitted spectrum of the C 1s peak, after platinum loading, is compared with... Figure 3 The C1s peak fitting spectrum showed little difference compared to the previous one, indicating that the C-containing functional groups hardly participated in the loading of the transition metal catalyst Pt; while the N1s peak fitting spectrum changed significantly after platinum loading. Figure 3 The single peak in the graph has become multi-peaked, indicating that during the Pt loading process, Pt atoms coordinate with nitrogen-containing functional groups, leading to significant fluctuations in the photoelectron binding energy. This confirms that Pt loading primarily relies on the lone pairs of electrons on the ligand surface and its own empty orbitals to form coordinate bonds. The XPS peak fitting diagram of Pt 4f can be split into two absorption peaks, corresponding to the Pt 4f5 / 2 and Pt 4f7 / 2 states of spin orbital splitting, respectively. Each absorption peak is represented by Pt... 4+ Pt 2+ and Pt 0 Fitting was performed. It can be concluded that the Pt in the catalyst mSiO2-PDA-Pt is... 4+ Pt 2+ and Pt 0 The contents were 20.16%, 50.26%, and 29.59%, respectively.

[0069] Figure 10 The product obtained from the cyclic catalytic utilization of the mSiO2-PDA-Pt catalyst prepared in Example 1. 1 1H NMR spectrum. The 1H NMR spectrum was performed using deuterated chloroform (CDCl3) as solvent and tetramethylsilane (TMS) as internal standard. The results are as follows: Figure 10 As shown, the absorption peak of CDCl3 is located at a chemical shift of 7.26 ppm. Figure 10 (a) is 1-octene 1 The H NMR spectrum shows absorption peaks at chemical shifts of 5.82 and 5.01 ppm, which are identified as CH2=CH-. Figure 10 (b) is dichloromethylsilane 1 The 1H NMR spectrum shows an absorption peak at a chemical shift of 5.59 ppm, which is considered to be the Si-H absorption peak. Figure 10 (c) and Figure 10 (d) represents the products of the hydrosilylation reaction catalyzed by the mSiO2-PDA-Pt catalyst in the first and second cycles. 1 The H NMR spectrum did not show absorption peaks for CH2=CH- and Si-H, but new absorption peaks appeared at 1.30 and 1.50 ppm, which are characteristic peaks of -Si-CH2-CH2- and -Si-CH2-CH2-CH2-, respectively. According to...1 The results of H NMR spectroscopy analysis showed a decrease in the content of CH2=CH- and Si-H, and a corresponding increase in the content of Si-C, further confirming that the catalyst mSiO2-PDA-Pt has high catalytic activity. According to... Figure 10 The 1H NMR spectrum of the addition product in (c) shows that the first catalytic efficiency is approximately 95%, and the product recovery is approximately 95%. Figure 10 The addition product of (d) can be calculated from the 1H NMR spectrum to show that the second catalytic efficiency is about 90% and the product recovery rate is about 90%.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a Pt catalyst, characterized in that, Includes the following steps: S1. Porous silica and dopamine are added to the first solvent, ultrasonically treated, and then sealed and soaked to obtain the first solution; Tris-HCl is added to the second solvent, and the pH of the solution is adjusted to 8.5~8.6 with ammonia / sodium hydroxide solution. The solution is mixed with the first solution and stirred at 25~35℃ for 24~48h. After the reaction is completed, the solid and liquid are separated, and the obtained solid is washed and dried to obtain the precursor. S2. Add the precursor and NaHCO3 to anhydrous ethanol, heat and stir under an oxygen-free atmosphere to 60~70℃, start adding chloroplatinic acid / ethanol solution dropwise, continue the reaction for 5~10h after the addition is complete, separate the solid and liquid, wash and dry the obtained solid to obtain the Pt catalyst. In step S1, the first solvent is at least one of ethanol, methanol, benzene, and toluene, and the mass-to-volume ratio of the porous silica to the first solvent is 0.1~0.3 g / mL. In step S1, the second solvent is at least one of methanol and toluene, and the mass-volume ratio of Tris-HCl to the second solvent is 0.0011~0.0026 g / mL; The ultrasonic treatment time is 10-20 minutes; the sealed soaking time is 0.5-2 hours.

2. The method for preparing the Pt catalyst according to claim 1, characterized in that, In step S1, the mass ratio of porous silica to dopamine is 3~6:

1.

3. The method for preparing the Pt catalyst according to claim 1, characterized in that, In step S1, the volume ratio of the first solvent to the second solvent is 1:4~7.

4. The method for preparing the Pt catalyst according to claim 1, characterized in that, In step S2, the mass ratio of the precursor to the NaHCO3 is 10:1~3, the mass-volume ratio of the precursor to the anhydrous ethanol is 40~60 g / mL, and the mass ratio of the chloroplatinic acid to the precursor is 10:1~3.

5. The method for preparing the Pt catalyst according to claim 1, characterized in that, In step S2, the concentration of the chloroplatinic acid / ethanol solution is 10~15 mg / mL, and the dropping rate is 3~10 mL / h.

6. The method for preparing the Pt catalyst according to claim 1, characterized in that, The stirring speed is 250-350 r / min.

7. The Pt catalyst prepared by the method according to any one of claims 1 to 6.

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