A device and method for preparing carbon-supported platinum nanocatalyst by solid phase mixing

Abstract

The present invention discloses a device and method for preparing carbon-supported platinum nanocatalysts by solid-phase mixing. The device comprises a precursor solution tank, a solution mixing device, a mixed solution tank, and a material tank which are connected in sequence by pipelines and pumps. The solution mixing device is provided with a spiral pipeline, and the material tank is placed inside the solid material mixing device. The method of use is as follows: the precursor solution is fully mixed through the spiral pipeline and ultrasonic treatment, a carbon carrier is added to the precursor mixed solution under stirring, or a precursor mixed solution is added to the carbon carrier for ultrasonic pretreatment, and after stirring and mixing, the mixture is dried, reduced, sintered, cleaned, and dried again. Compared with the prior art, the operation process of the present invention is simple, controllable, and has a short cycle. It does not require the addition of organic surfactants and complexing agents. It can be filtered and cleaned with pure water, and a large amount of polluted waste liquid will not be generated. It can realize batch and continuous production of high-loaded PtC catalysts, and is suitable for large-scale preparation of PtC catalysts for commercial applications.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cell catalyst materials, and in particular relates to a device and method for preparing carbon-supported platinum nanocatalysts by solid-phase mixing. Background Art

[0002] Fuel cells use hydrogen as fuel and have outstanding advantages such as high energy density, long driving range, clean and environmentally friendly. They are considered to be the most ideal new energy technology in the 21st century and have broad application prospects in the fields of automobiles and energy storage. The main mechanism of action of fuel cells is to convert the chemical energy of the reaction of hydrogen and oxygen into electrical energy through electrochemical reactions. The kinetics of this process is very slow, and a large amount of platinum (Pt) catalysts are required to accelerate the reaction and improve the energy conversion efficiency. Therefore, catalysts are indispensable key materials. The commercial fuel cell catalysts currently used are carbon-supported platinum (PtC)-based catalysts. The large-scale preparation of low-cost, high-performance PtC catalysts through simple and environmentally friendly processes and devices is the key to accelerating and promoting the commercial application of fuel cells.

[0003] When preparing PtC catalysts, the size and dispersion of catalyst particles are key. At the same time, ensuring high loading (more than 20% Pt metal content) and improving the utilization rate of precious metal Pt are conducive to reducing costs and are the mainstream direction of commercial applications. At present, the preparation methods of PtC catalysts can be divided into two categories, liquid phase method and solid phase method. The liquid phase method requires the addition of reducing agents and surfactants for treatment so that Pt nanoparticles are reduced and adsorbed on the surface of the carbon carrier and avoid particle agglomeration. Subsequent steps require a large amount of aqueous or organic solvents for filtration and cleaning, which produces a large amount of organic waste liquid, and the filtration efficiency is low, which is not conducive to large-scale production. The solid-phase method mainly involves mixing a Pt-containing precursor solution with a carbon carrier, drying it, and treating it in a reducing atmosphere to obtain PtC particles. Adjusting the precursor solution to acidity is a common technical means of the solid-phase method. Although this method can obtain evenly dispersed Pt particles, due to its principle of electrostatic adsorption, it can only prepare PtC catalysts with a lower loading (Pt content <10%), which cannot meet the performance requirements of commercial fuel cell catalysts. In addition, adding a chelating agent to the precursor solution to improve the dispersibility of Pt particles and reduce the particle size is also a common technical means for preparing PtC catalysts by the solid-phase method. However, the introduction of a chelating agent will cause the surface of the Pt particles to be unclean, affecting the catalytic performance of the catalyst. It also requires a large amount of aqueous or organic solvents for filtration and cleaning, which causes environmental pollution.

[0004] In summary, it can be seen that in the existing methods for preparing PtC catalysts, surfactants or chelating agents are usually required to be added, which not only affects the cleanliness of the catalyst surface and is not conducive to the catalytic reaction, but also requires the use of a large amount of organic solvents for subsequent filtration and cleaning, generating a large amount of polluted waste liquid. In addition, it is difficult to obtain a high-load PtC catalyst, which is not conducive to commercial development. Summary of the invention

[0005] One of the purposes of the present invention is to provide a device for preparing carbon-supported platinum nanocatalysts by solid-phase mixing in view of the shortcomings of the prior art. The operation process is simple, controllable, and has a short cycle. It can realize batch continuous production of high-loaded PtC catalysts and is suitable for large-scale preparation of PtC catalysts for commercial applications.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A device for preparing carbon-supported platinum nanocatalyst by solid phase mixing comprises a precursor solution tank, a solution mixing device, a mixed solution tank and a material tank which are sequentially connected through pipelines and pumps, wherein the solution mixing device is provided with a spiral pipeline and the material tank is placed inside the solid material mixing device.

[0008] Preferably, the precursor solution is gathered from the precursor solution tank to the solution mixing device and enters the spiral pipeline, and the length of the spiral pipeline is at least 1 meter.

[0009] Preferably, the solution mixing device is loaded with an aqueous solution, and an ultrasonic generator is provided to perform ultrasonic treatment on the precursor solution entering the spiral pipe.

[0010] Preferably, the solid material mixing device is loaded with an aqueous solution, and an ultrasonic generator is provided to perform ultrasonic treatment on the material in the material tank. A heater may also be provided to heat the aqueous solution in the internal device, thereby heating the material in the material tank.

[0011] Preferably, a cover plate is provided on the upper portion of the solid material mixing device, and a slide rail is provided on the bottom of the cover plate, which can slide to both sides. When opened, the material tank can be placed in the solid material mixing device, and when closed, the material tank can be clamped and fixed.

[0012] Preferably, the top of the material tank is open and is provided with a material tank upper cover for sealing, and the material tank upper cover is connected to the material tank by a hinge lock.

[0013] Preferably, the upper part of the upper cover of the material tank is open, so as to allow the stirrer of the stirring device to extend into the material tank to stir and mix the materials in the material tank.

[0014] Another object of the present invention is to use the device of the present invention to prepare a carbon-supported platinum nanocatalyst, without adding an organic surfactant and a complexing agent, and only requires filtering and washing with pure water, without generating a large amount of polluted waste liquid, which is method one or method two;

[0015] The method 1 comprises the following steps:

[0016] The first step is to add a chloroplatinic acid precursor solution and a sodium hydroxide precursor solution with a molar ratio of 1:4-1:9 into a precursor solution tank, respectively, and collect them into a solution mixing device through a pump, and enter a spiral pipeline, and turn on an ultrasonic device in the solution mixing device to perform ultrasonic treatment on the precursor solution;

[0017] In the second step, the precursor solution is ultrasonically mixed in the solution mixing device and then enters the mixed solution tank. After all the precursor mixed solution enters the mixed solution tank, the pump between the mixed solution tank and the material tank is turned on, and 70%-90% of the precursor mixed solution is pumped into the material tank;

[0018] The third step is to start the agitator and add the carbon support while the precursor mixed solution in the tank is being stirred. The agitator speed is 50-150 rpm.

[0019] Step 4: Continue to pump the remaining 10%-30% of the precursor mixture into the tank to wash off the carbon carrier splashed on the tank wall around the tank, and adjust the stirrer speed to 150-250 rpm, and continue stirring for 30-60 minutes;

[0020] Step 5: After the stirring is completed, the slurry is dried, sintered in a reducing atmosphere of H2+Ar, washed and dried again to obtain a carbon-supported platinum nanocatalyst;

[0021] The second method comprises the following steps:

[0022] The first step is to add a chloroplatinic acid precursor solution and a sodium hydroxide precursor solution with a molar ratio of 1:4-1:9 into a precursor solution tank, respectively, and collect them into a solution mixing device through a pump, and enter a spiral pipeline, and turn on an ultrasonic device in the solution mixing device to perform ultrasonic treatment on the precursor solution;

[0023] In the second step, the precursor solution is ultrasonically mixed in the solution mixing device and then enters the mixed solution tank. After all the precursor mixed solution enters the mixed solution tank, the pump between the mixed solution tank and the material tank is turned on;

[0024] The third step is to add the carbon carrier into the material tank, start the pump to add all the precursor mixed solution in the mixed solution tank into the material tank, and then start the ultrasonic of the solid material mixing device for 5-15 minutes;

[0025] Step 4: After the ultrasound is finished, turn on the stirrer and stir at a speed of 150-250 rpm for 20-50 min;

[0026] In the fifth step, the slurry after stirring is dried, sintered in a reducing atmosphere of H2+Ar, cleaned and dried again to obtain a carbon-supported platinum nanocatalyst.

[0027] Preferably, the ratio of the carbon carrier to the precursor mixed solution is 30-80 g / L, and the volume of the chloroplatinic acid precursor solution is calculated based on the Pt loading in the carbon-supported platinum nanocatalyst being 20-60%.

[0028] Preferably, the sintering temperature is 200-500°C, the time is 0.5-4h, and the cleaning is carried out by aqueous solution.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] First, the preparation device and method have a simple operation process and a short cycle, are easy to scale up and produce continuously, do not require the use of surfactants or complexing agents, and thus do not cause organic wastewater pollution. The reduction generates NaCl rather than HCl acidic waste gas, and NaCl can be removed after washing with water, thereby avoiding the poisoning effect of Cl on the Pt catalyst.

[0031] Second, the various components of the device are independent of each other and easy to clean and to discover and solve problems. The precursor solution is fully ultrasonically mixed in the spiral pipe and then mixed with the carbon carrier. The carbon carrier is added to the stirred precursor solution, or a short period of ultrasonic treatment is performed before stirring the precursor solution and the carbon carrier. This is conducive to the full contact and adsorption of the Pt-containing precursor solution and the carbon carrier, and then stirring and mixing to promote the amount and uniform dispersion of Pt on the carbon carrier, thereby improving the catalytic performance of the catalyst.

[0032] Third, the precursor solution is composed of low-cost chloroplatinic acid and sodium hydroxide, which are easy to prepare and evenly mix. At the same time, the addition of NaOH can control the particle size of the catalyst and the dispersion of Pt, thereby reducing the size of the catalyst nanoparticles and improving the utilization of Pt. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of the present invention.

[0034] Figure 2 (a) TEM image and (b) XRD image of the carbon-supported platinum nanocatalyst prepared by method 1 in Example 1 of the present invention.

[0035] Figure 3 This is a graph showing the electrochemical performance of the carbon-supported platinum nanocatalyst prepared by method 1 in Example 1 of the present invention.

[0036] Figure 4 (a) TEM image and (b) XRD image of the carbon-supported platinum nanocatalyst prepared by method 2 in Example 1 of the present invention.

[0037] Figure 5 This is a graph showing the electrochemical performance of the carbon-supported platinum nanocatalyst prepared by method 2 in Example 1 of the present invention. DETAILED DESCRIPTION

[0038] The present invention and its beneficial effects are described in detail below in conjunction with specific embodiments, but the embodiments of the present invention are not limited thereto.

[0039] Example 1

[0040] like Figure 1 As shown, this embodiment provides a device for preparing carbon-supported platinum nanocatalyst by solid phase mixing, comprising a precursor solution tank 1, a solution mixing device 3, a mixed solution tank 4, and a material tank 5 which are connected in sequence through a pipeline and a pump 2, wherein the solution mixing device 3 is provided with a spiral pipeline 31, and the material tank 5 is placed inside the solid material mixing device 6.

[0041] The precursor solution is collected from the precursor solution tank 1 through the pump 2 to the solution mixing device 3 and enters the spiral pipe 31 . The length of the spiral pipe is 1 meter.

[0042] The solution mixing device 3 is loaded with aqueous solution and is provided with an ultrasonic generator to perform ultrasonic treatment on the precursor solution entering the spiral pipe 31 .

[0043] The solid material mixing device 6 is loaded with aqueous solution and is provided with an ultrasonic generator to perform ultrasonic treatment on the material in the material tank 5 .

[0044] A cover plate 9 is provided on the top of the solid material mixing device 6, and a slide rail is provided at the bottom of the cover plate 9, which can slide to both sides. When opened, the material tank 5 can be placed in the solid material mixing device 6, and when closed, the material tank 5 can be clamped and fixed.

[0045] The top of the material tank 5 is open and is provided with a material tank upper cover 7 for sealing. The material tank upper cover 7 is connected to the material tank 5 through a hinge lock.

[0046] The upper part of the material tank cover 7 is open, which is used for extending the stirrer of the stirring device 8 into the material tank 5 to stir and mix the materials in the material tank 5.

[0047] There are two methods for preparing carbon-supported platinum nanocatalysts using the reaction device:

[0048] Method 1 includes the following steps:

[0049] In the first step, a chloroplatinic acid precursor solution and a sodium hydroxide precursor solution with a molar ratio of 1:5 are added to a precursor solution tank respectively, and the mixture is pumped to a solution mixing device, enters a spiral pipe, and an ultrasonic device in the solution mixing device is turned on to perform ultrasonic treatment on the precursor solution;

[0050] In the second step, the precursor solution is ultrasonically mixed in the solution mixing device and then enters the mixed solution tank. After all the precursor mixed solution enters the mixed solution tank, the pump between the mixed solution tank and the material tank is turned on, and 80% of the precursor mixed solution is pumped into the material tank;

[0051] The third step is to start the agitator and add the carbon support while the precursor mixed solution in the material tank is being stirred. The agitator speed is 100 rpm.

[0052] Step 4: Continue to pump the remaining 20% ​​of the precursor mixture into the tank to wash off the carbon carrier splashed on the tank wall around the tank, and adjust the stirrer speed to 150 rpm and continue stirring for 30 minutes;

[0053] The fifth step is to dry the slurry after stirring. 2 +Ar reducing atmosphere, sintering, washing and re-drying to obtain the carbon-supported platinum nanocatalyst;

[0054] Method 2 includes the following steps:

[0055] In the first step, a chloroplatinic acid precursor solution and a sodium hydroxide precursor solution with a molar ratio of 1:5 are added to a precursor solution tank respectively, and the mixture is pumped to a solution mixing device, enters a spiral pipe, and an ultrasonic device in the solution mixing device is turned on to perform ultrasonic treatment on the precursor solution;

[0056] In the second step, the precursor solution is ultrasonically mixed in the solution mixing device and then enters the mixed solution tank. After all the precursor mixed solution enters the mixed solution tank, the pump between the mixed solution tank and the material tank is turned on;

[0057] The third step is to add the carbon carrier into the material tank, turn on the pump to add all the precursor mixed solution in the mixed solution tank into the material tank, and then turn on the ultrasound of the solid material mixing device for 10 minutes;

[0058] Step 4: After the ultrasound is finished, turn on the stirrer and stir at 150 rpm for 20 min;

[0059] The fifth step is to dry the slurry after stirring. 2 The carbon-supported platinum nanocatalyst is obtained by sintering, washing and drying in a reducing atmosphere of +Ar.

[0060] The ratio of the carbon carrier to the precursor mixed solution is 50 g / L, and the volume of the chloroplatinic acid precursor solution is calculated based on the Pt loading of 40% in the carbon-supported platinum nanocatalyst.

[0061] The sintering temperature is 300°C, the time is 1 h, and the cleaning is carried out using an aqueous solution.

[0062] like Figure 2 As shown, the carbon-supported platinum nanocatalyst particles prepared by method 1 of this example are evenly dispersed, and the catalyst particle size is about 3.5 nm according to Pt (111), which is small in size. Figure 3 The electrochemical active area of ​​the catalyst was 61 m 2 / g Pt The mass activity was 0.16 A / mg at 0.9 V vs. RHE. Pt , the area specific activity is about 0.26 mA / cm 2 Pt .

[0063] Figure 4 The TEM image and XRD image of the carbon-supported platinum nanocatalyst prepared by method 2 of this embodiment show that the catalyst particles are evenly dispersed and small in size, about 3.6 nm. Figure 5 The electrochemical performance diagram of the catalyst is shown in Figure 2. The electrochemical active area is 59 m 2 / g Pt The mass activity was 0.15 A / mg at 0.9 V vs. RHE. Pt , the area specific activity is about 0.26 mA / cm 2 Pt .

[0064] Example 2

[0065] The difference from Example 1 is that the preparation method of the carbon-supported platinum nanocatalyst comprises the following steps:

[0066] In the first step, a chloroplatinic acid precursor solution and a sodium hydroxide precursor solution with a molar ratio of 1:6 are added to a precursor solution tank respectively, and the mixture is pumped to a solution mixing device, enters a spiral pipe, and an ultrasonic device in the solution mixing device is turned on to perform ultrasonic treatment on the precursor solution;

[0067] In the second step, the precursor solution is ultrasonically mixed in the solution mixing device and then enters the mixed solution tank. After all the precursor mixed solution enters the mixed solution tank, the pump between the mixed solution tank and the material tank is turned on, and 90% of the precursor mixed solution is pumped into the material tank;

[0068] The third step is to start the agitator and add the carbon support while the precursor mixed solution in the material tank is stirred. The agitator speed is 120 rpm.

[0069] Step 4: Continue to pump the remaining 10% of the precursor mixture into the tank to wash off the carbon carrier splashed on the tank wall around the tank, and adjust the stirrer speed to 200 rpm and continue stirring for 45 minutes;

[0070] The fifth step is to dry the slurry after stirring. 2 +Ar reducing atmosphere, sintering, washing and re-drying to obtain the carbon-supported platinum nanocatalyst;

[0071] The ratio of the carbon carrier to the precursor mixed solution is 60 g / L, and the volume of the chloroplatinic acid precursor solution is calculated based on the Pt loading in the carbon-supported platinum nanocatalyst being 60%.

[0072] The sintering temperature is 250°C, the time is 2h, and the cleaning is carried out using an aqueous solution.

[0073] Example 3

[0074] The difference from Example 1 is that the preparation method of the carbon-supported platinum nanocatalyst comprises the following steps:

[0075] In the first step, a chloroplatinic acid precursor solution and a sodium hydroxide precursor solution with a molar ratio of 1:8 are added to a precursor solution tank respectively, and the mixture is pumped to a solution mixing device, enters a spiral pipe, and an ultrasonic device in the solution mixing device is turned on to perform ultrasonic treatment on the precursor solution;

[0076] In the second step, the precursor solution is ultrasonically mixed in the solution mixing device and then enters the mixed solution tank. After all the precursor mixed solution enters the mixed solution tank, the pump between the mixed solution tank and the material tank is turned on;

[0077] The third step is to add the carbon carrier into the material tank, turn on the pump to add all the precursor mixed solution in the mixed solution tank into the material tank, and then turn on the ultrasound of the solid material mixing device for 5 minutes;

[0078] Step 4: After the ultrasound is finished, turn on the stirrer and stir at 180 rpm for 30 min;

[0079] The fifth step is to dry the slurry after stirring. 2 The carbon-supported platinum nanocatalyst is obtained by sintering, washing and drying in a reducing atmosphere of +Ar.

[0080] The ratio of the carbon carrier to the precursor mixed solution is 70 g / L, and the volume of the chloroplatinic acid precursor solution is calculated based on a Pt loading of 20% in the carbon-supported platinum nanocatalyst.

[0081] The sintering temperature is 500°C, the time is 0.5h, and the cleaning is carried out with an aqueous solution.

[0082] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs can also change and modify the above embodiment. Therefore, the present invention is not limited to the above specific embodiment, and any obvious improvement, replacement or modification made by those skilled in the art on the basis of the present invention belongs to the protection scope of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A device for preparing carbon-supported platinum nanocatalyst by solid phase mixing, characterized in that: It includes a precursor solution tank, a solution mixing device, a mixed solution tank, and a material tank which are connected in sequence through pipelines and pumps, wherein the solution mixing device is provided with a spiral pipeline, and the material tank is placed inside the solid material mixing device; The precursor solution is collected from the precursor solution tank to the solution mixing device and enters the spiral pipeline, and the length of the spiral pipeline is at least 1 meter; The solution mixing device is loaded with aqueous solution and is provided with an ultrasonic generator to perform ultrasonic treatment on the precursor solution entering the spiral pipe; The solid material mixing device is loaded with an aqueous solution, and an ultrasonic generator is provided to perform ultrasonic treatment on the material in the material tank. A heater is also provided to heat the aqueous solution in the internal device, thereby heating the material in the material tank.

2. The device for preparing carbon-supported platinum nanocatalyst by solid phase mixing according to claim 1, characterized in that: A cover plate is provided on the upper part of the solid material mixing device, and a slide rail is provided on the bottom of the cover plate, which can slide to both sides. When it is opened, the material tank can be placed in the solid material mixing device, and when it is closed, the material tank can be clamped and fixed.

3. The device for preparing carbon-supported platinum nanocatalyst by solid phase mixing according to claim 1, characterized in that: The top of the material tank is open and is provided with a material tank upper cover for sealing. The material tank upper cover is connected to the material tank through a hinge lock.

4. The device for preparing carbon-supported platinum nanocatalyst by solid phase mixing according to claim 3, characterized in that: The upper part of the material tank cover is open, which is used for extending the stirrer of the stirring device into the material tank to stir and mix the materials in the material tank.

5. A method for preparing a carbon-supported platinum nanocatalyst using the device according to any one of claims 1 to 4, characterized in that: One of the following two methods: Method 1 includes the following steps: The first step is to add a chloroplatinic acid precursor solution and a sodium hydroxide precursor solution with a molar ratio of 1:4-1:9 into a precursor solution tank, respectively, and collect them into a solution mixing device through a pump, and enter a spiral pipeline, and turn on an ultrasonic device in the solution mixing device to perform ultrasonic treatment on the precursor solution; In the second step, the precursor solution is ultrasonically mixed in the solution mixing device and then enters the mixed solution tank. After all the precursor mixed solution enters the mixed solution tank, the pump between the mixed solution tank and the material tank is turned on, and 70%-90% of the precursor mixed solution is pumped into the material tank; The third step is to start the agitator and add the carbon support while the precursor mixed solution in the tank is being stirred. The agitator speed is 50-150 rpm. Step 4: Continue to pump the remaining 10%-30% of the precursor mixture into the tank to wash off the carbon carrier splashed on the tank wall around the tank, and adjust the stirrer speed to 150-250 rpm, and continue stirring for 30-60 minutes; Step 5: After the stirring is completed, the slurry is dried, sintered in a reducing atmosphere of H2 +Ar, washed and dried again to obtain a carbon-supported platinum nanocatalyst; Method 2 includes the following steps: The first step is to add a chloroplatinic acid precursor solution and a sodium hydroxide precursor solution with a molar ratio of 1:4-1:9 into a precursor solution tank, respectively, and collect them into a solution mixing device through a pump, and enter a spiral pipeline, and turn on an ultrasonic device in the solution mixing device to perform ultrasonic treatment on the precursor solution; In the second step, the precursor solution is ultrasonically mixed in the solution mixing device and then enters the mixed solution tank. After all the precursor mixed solution enters the mixed solution tank, the pump between the mixed solution tank and the material tank is turned on; The third step is to add the carbon carrier into the material tank, start the pump to add all the precursor mixed solution in the mixed solution tank into the material tank, and then start the ultrasonic of the solid material mixing device for 5-15 minutes; Step 4: After the ultrasound is finished, turn on the stirrer and stir at a speed of 150-250 rpm for 20-50 min; In the fifth step, the slurry after stirring is dried, sintered in a reducing atmosphere of H2 +Ar, washed and dried again to obtain a carbon-supported platinum nanocatalyst.

6. The method according to claim 5, characterized in that The ratio of the carbon carrier to the precursor mixed solution is 30-80 g / L, and the volume of the chloroplatinic acid precursor solution is calculated based on the Pt loading in the carbon-supported platinum nanocatalyst being 20-60%.

7. The method according to claim 5, characterized in that The sintering temperature is 200-500°C, the time is 0.5-4h, and the cleaning is carried out with an aqueous solution.

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