CN113555567A

CN113555567A - Platinum-carbon catalyst and preparation method thereof

Info

Publication number: CN113555567A
Application number: CN202110831034.5A
Authority: CN
Inventors: 包喆宇; 刘倩; 刘凯; 张义煌; 陈杰
Original assignee: Wuxi Weifu High Technology Group Co Ltd
Current assignee: Wuxi Weifu High Technology Group Co Ltd
Priority date: 2021-07-22
Filing date: 2021-07-22
Publication date: 2021-10-26

Abstract

The invention provides a preparation method of a platinum-carbon catalyst, which comprises the following steps: step 1, preparing a mixed solution: adding chloroplatinic acid hexahydrate, a carbon material, polyol and a protective agent into water, uniformly stirring, and adding alkali to adjust the pH value to obtain a mixed solution with the pH value of 6-12; the mixed solution comprises the following components in parts by weight: 100 parts of water, 10-55 parts of a protective agent, 4-6 parts of chloroplatinic acid hexahydrate and 1.1-1.4 parts of a carbon material; step 2, pumping the mixed solution into a microchannel reactor through a pump for reaction to obtain a reaction product; and 3, washing the reaction product with ultrapure water, performing filter pressing, and drying filter residues in an oven to obtain the platinum-carbon catalyst. The invention mainly uses water as solvent, avoids the problems of safety, environmental protection and the like caused by using a large amount of alcohol solvent, and reduces the cost; the invention carries out solid-liquid phase reaction in the microchannel reactor, greatly improves the efficiency of mass and heat transfer and improves the reaction efficiency.

Description

Platinum-carbon catalyst and preparation method thereof

Technical Field

The invention belongs to the field of new energy materials and application, and particularly relates to a platinum-carbon catalyst and a preparation method thereof.

Background

At present, Proton Exchange Membrane Fuel Cells (PEMFCs) are a new energy technology, and have been widely used in the automotive field due to their advantages of high energy conversion efficiency, no pollution, low operating noise, and the like. Among them, the core material platinum carbon catalyst in PEMFCs is currently the focus of research as one of the most effective hydrogen evolution catalysts. However, the research of the domestic platinum-carbon catalyst is still in the test stage, and the catalyst mainly depends on the import from abroad, which seriously restricts the autonomous development of the domestic fuel cell. Therefore, it is urgent to produce a high-speed, high-efficiency and low-cost platinum-carbon catalyst.

In the traditional preparation process of the platinum-carbon catalyst, ethylene glycol is mainly used as a solvent, platinum is reduced by the ethylene glycol, but the addition of excessive ethylene glycol also brings certain potential safety hazard to donor ties. In addition, the platinum-carbon catalyst at the present stage is mainly prepared by a microwave reduction method, and therefore, the problems of uneven heat transfer and the like exist in the reaction process.

The micro-reactor is a chemical reaction system with micron-scale unit reaction interface width, integrates various element technologies such as material technology, micro-machining technology, sensor technology and control technology, takes reaction as a main purpose, takes one or more micro-reactors as a main purpose, and simultaneously can also comprise a micro-reaction system of key components such as micro heat exchange, micro separation, micro extraction and the like, a micro sensor, a micro actuator and the like.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a high-speed, high-efficiency, low-cost and environment-friendly synthesis method of a platinum-carbon catalyst, and the platinum-carbon catalyst prepared by the method has larger electrochemical active area and higher stability. In order to achieve the technical purpose, the embodiment of the invention adopts the technical scheme that:

in a first aspect, an embodiment of the present invention provides a preparation method of a platinum-carbon catalyst, including the following steps:

step 1, preparing a mixed solution: adding chloroplatinic acid hexahydrate, a carbon material, polyol and a protective agent into water, uniformly stirring, and adding alkali to adjust the pH value to obtain a mixed solution with the pH value of 6-12;

the mixed solution comprises the following components in parts by weight: 100 parts of water, 10-55 parts of a protective agent, 4-6 parts of chloroplatinic acid hexahydrate and 1.1-1.4 parts of a carbon material;

step 2, pumping the mixed solution into a microchannel reactor through a pump for reaction to obtain a reaction product;

step 3, washing the reaction product with ultrapure water, and performing filter pressing to obtain filter residue and filtrate; and drying the filter residue by using an oven to obtain the platinum-carbon catalyst.

Preferably, in the step 1, the carbon material is selected from one or more of ketjen black, Vulcan XC-72, graphene, carbon nanotubes and carbon fibers;

preferably, in step 1, the polyhydric alcohol is selected from one or more of n-propanol, isopropanol and ethylene glycol;

the ratio of water to the polyhydric alcohol is 3-15 in parts by volume;

preferably, in the step 1, the protective agent is one or more selected from ethylenediamine tetraacetic acid, potassium sodium tartrate, dithizone, ammonium citrate and 8-hydroxyquinoline;

the molar ratio of the protective agent to chloroplatinic acid hexahydrate is 5-15;

preferably, in the step 1, the alkali is selected from one or more of inorganic alkalis;

the inorganic alkali is selected from one or more of ammonia water, sodium carbonate and sodium hydroxide;

preferably, in the step 2, the reaction temperature of the microchannel reactor is 120-180 ℃, and the reaction time is 1-8 h.

Preferably, in the step 3, the drying temperature of the oven is 60-80 ℃.

Specifically, in step 1, the mixed solution comprises the following components in parts by weight:

100 parts of water, 12.5-20 parts of protective agent, 4.5-5.5 parts of chloroplatinic acid hexahydrate and 1.2-1.3 parts of carbon material;

the ratio of water to the polyhydric alcohol is 6-12 in parts by volume;

wherein the molar ratio of the protective agent to chloroplatinic acid hexahydrate is 7-13;

the pH value of the mixed solution is 8-12;

in the step 2, the reaction temperature of the microchannel reactor is 140-160 ℃, and the reaction time is 3-6 h.

In a second aspect, the embodiment of the invention also provides a platinum carbon catalyst prepared by the preparation method.

The technical scheme provided by the embodiment of the invention has the following beneficial effects:

1) the invention mainly uses water as solvent, avoids the problems of safety, environmental protection and the like caused by using a large amount of alcohol solvent, and simultaneously reduces the production cost.

2) The invention is a solid-liquid phase reaction in a micro-channel reactor, which can greatly improve the efficiency of mass and heat transfer, thereby improving the reaction efficiency.

3) The invention adds the protective agent into the reaction system, can adjust the particle size of the platinum particles, and plays a role in dispersion when adding the polyalcohol and reducing the platinum catalyst, thereby ensuring the catalytic activity of the platinum metal.

Drawings

FIG. 1 is a process flow diagram of catalyst preparation according to an embodiment of the present invention.

Figure 2 is an XRD pattern of the catalyst prepared in example 2 of the present invention.

FIG. 3 is a comparison of cyclic voltammograms of the catalyst prepared in example 2 of the present invention and a commercial platinum carbon catalyst.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

step 1, preparing a mixed solution: adding chloroplatinic acid hexahydrate, a carbon material, polyol and a protective agent into water, uniformly stirring, and adding alkali to adjust the pH value to obtain a mixed solution with the pH value of 6-12, wherein the mixed solution can be 6, 7, 8, 9, 10, 11, 12 and the like;

the mixed solution comprises the following components in parts by weight: 100 parts of water, 10-55 parts of protective agent, such as 10 parts, 20 parts, 30 parts, 40 parts, 50 parts, 55 parts and the like, 4-6 parts of chloroplatinic acid hexahydrate, such as 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts and the like, and 1.1-1.4 parts of carbon material, such as 1.1 part, 1.2 parts, 1.3 parts, 1.4 parts and the like;

more preferably, the carbon material is Vulcan XC-72.

the ratio of water to the polyol is 3-15 by volume, for example, 3, 5, 7, 9, 11, 13, 15, etc.;

more preferably, the polyol is ethylene glycol.

The polyol is added into the reaction system, so that the platinum catalyst can be reduced, and the dispersion effect can be achieved, and the platinum is prevented from agglomerating to influence the effect of the catalyst.

the molar ratio of the protective agent to the chloroplatinic acid hexahydrate is 5-15, and can be 5, 7, 9, 11, 13, 15 and the like;

more preferably, the protectant is ethylenediaminetetraacetic acid.

The protective agent is added into the reaction system, so that the particle size of the platinum particles can be adjusted, and the catalytic activity of the platinum metal is ensured.

more preferably, the base is sodium carbonate and/or sodium hydroxide.

Preferably, in the step 2, the reaction temperature of the microchannel reactor is 120-180 ℃, for example, 120 ℃, 140 ℃, 160 ℃, 180 ℃ and the like, and the reaction time is 1-8 h, for example, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h and the like.

Preferably, in step 3, the drying temperature of the oven is 60 to 80 ℃, for example, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃ and the like.

100 parts of water, 12.5 to 20 parts of a protective agent, for example, 12.5 parts, 14 parts, 16 parts, 18 parts, 20 parts and the like, 4.5 to 5.5 parts, for example, 4.5 parts, 5 parts, 5.5 parts and the like of chloroplatinic acid hexahydrate, 1.2 to 1.3 parts of a carbon material, for example, 1.2 parts, 1.22 parts, 1.24 parts, 1.26 parts, 1.28 parts, 1.3 parts and the like;

the ratio of water to the polyol is 6-12 in parts by volume, and can be 6, 7, 8, 9, 10, 11, 12 and the like;

wherein the molar ratio of the protective agent to chloroplatinic acid hexahydrate is 7-13, and can be 7, 8, 9, 10, 11, 12, 13 and the like;

the pH value of the mixed solution is 8-12, for example, 8, 9, 10, 11, 12 and the like;

in the step 2, the reaction temperature of the microchannel reactor is 140 to 160 ℃, for example, 140 ℃, 145 ℃, 150 ℃, 155 ℃, 160 ℃ and the like, and the reaction time is 3 to 6 hours, for example, 3 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours and the like.

In the following specific examples, those whose operations are not subject to the conditions indicated, were carried out according to the usual conditions or conditions recommended by the manufacturer. All raw materials are conventional products which can be obtained commercially by manufacturers and specifications.

Wherein chloroplatinic acid hexahydrate (99.9%) was purchased from shengyila chemical company ltd, Nanjing, ethylene glycol (analytically pure, 99%) and ethylenediaminetetraacetic acid (analytically pure, 99.9%) were purchased from Chemicals group, Inc., and Nafion solution (5 wt%, model D520) was purchased from science and technology company, Beijing, of Waxico, China.

The test apparatus for X-ray powder diffraction (XRD) was a Rigaku MiniFlex 600X-ray diffractometer from Rigaku corporation, Japan. The test conditions were: power: 0.60 kW, 2 θ test range: +2 ° +145 °, θ/2 θ axis minimum step angle: 0.01 ° (2 θ), constant scan speed: 0.01-100 DEG/min, scanning range: 2 θ =30 ° to 90 °, scanning speed: 5 °/min, step size: 0.02 degree.

The test equipment for Cyclic Voltammetry (CV) was the 760E electrochemical workstation of shanghai chenhua instruments ltd. The test conditions were: the formula of the catalyst ink is 0.75ml of ultrapure water, 0.25ml of isopropanol and 0.025ml of Nafion membrane solution, the catalyst is dispersed in the solvent by using a cell crusher, and the ultrasonic treatment is carried out for 30min to form uniformly dispersed ink. A glassy carbon electrode is adopted as a titration electrode, 0.5M sulfuric acid solution is used as electrolyte, 15min of nitrogen is introduced before testing, the testing scanning range is-0.25V-1V, and the scanning speed is 0.05V/s and 0.02V/s.

Example 1

A preparation method of a platinum-carbon catalyst comprises the following steps:

step 1, dissolving 4.4g of Ketjen black and 16g of chloroplatinic acid hexahydrate in 400mL of deionized water, adding 26.7mL of ethylene glycol and 40g of ethylenediaminetetraacetic acid (EDTA), fully stirring and uniformly mixing, and dropwise adding sodium carbonate to adjust the pH value to 6 to obtain a mixed solution;

step 2, pumping the mixed solution obtained in the step 1 into a microchannel reactor through a pump, setting the reaction temperature of the microchannel reactor to be 120 ℃, setting the reaction time to be 3 hours, and naturally cooling the mixture to room temperature to obtain a reaction product;

and 3, washing and filter-pressing the reaction product, and drying the filter residue in an air-blast drying oven, wherein the temperature of the drying oven is set to be 60 ℃, and finally obtaining black catalyst powder.

Example 2

step 1, dissolving 4.4g of Ketjen black and 16g of chloroplatinic acid hexahydrate in 400mL of deionized water, adding 44mL of ethylene glycol and 81.33g of EDTA, fully stirring and uniformly mixing, and dropwise adding sodium carbonate to adjust the pH value to 9 to obtain a mixed solution;

step 2, pumping the mixed solution obtained in the step 1 into a microchannel reactor through a pump, setting the reaction temperature of the microchannel reactor to be 140 ℃, setting the reaction time to be 6 hours, and naturally cooling the mixture to room temperature to obtain a reaction product;

and 3, washing and filter-pressing the reaction product, and drying the filter residue in a forced air drying oven, wherein the temperature of the drying oven is set to be 60 ℃, and finally obtaining black catalyst powder.

Example 3

step 1, dissolving 5.2g of Ketjen black and 18g of chloroplatinic acid hexahydrate in 400mL of deionized water, adding 50mL of ethylene glycol and 75g of EDTA, fully stirring and uniformly mixing, and dropwise adding sodium hydroxide to adjust the pH value to 12 to obtain a mixed solution;

step 2, pumping the mixed solution obtained in the step 1 into a microchannel reactor through a pump, setting the reaction temperature of the microchannel reactor to be 180 ℃, setting the reaction time to be 1h, and naturally cooling to room temperature to obtain a reaction product;

and 3, washing and filter-pressing the reaction product, and drying the filter residue in a forced air drying oven, wherein the temperature of the drying oven is set to 80 ℃, and finally obtaining black catalyst powder.

Example 4

step 1, dissolving 6.8g of Ketjen black and 24g of chloroplatinic acid hexahydrate in 400mL of deionized water, adding 133.33mL of ethylene glycol and 100g of EDTA, fully stirring and uniformly mixing, and dropwise adding sodium hydroxide to adjust the pH value to 12 to obtain a mixed solution;

step 2, pumping the mixed solution obtained in the step 1 into a microchannel reactor through a pump, setting the reaction temperature of the microchannel reactor to be 180 ℃, setting the reaction time to be 8 hours, and naturally cooling the mixture to room temperature to obtain a reaction product;

Example 5

step 1, dissolving 5.2g of Vulcan XC-72 and 22g of chloroplatinic acid hexahydrate in 400mL of deionized water, adding 66.67mL of ethylene glycol and 80g of EDTA, fully stirring and uniformly mixing, and dropwise adding sodium hydroxide to adjust the pH value to 11 to obtain a mixed solution;

step 2, pumping the mixed solution obtained in the step 1 into a microchannel reactor through a pump, setting the reaction temperature of the microchannel reactor to be 160 ℃, setting the reaction time to be 6 hours, and naturally cooling the mixture to room temperature to obtain a reaction product;

Example 6

step 1, dissolving 4.8g of Vulcan XC-72 and 18g of chloroplatinic acid hexahydrate in 400mL of deionized water, adding 33.33mL of ethylene glycol and 50g of EDTA, fully stirring and uniformly mixing, and dropwise adding sodium hydroxide to adjust the pH value to 8;

step 2, pumping the mixed solution obtained in the step 1 into a microchannel reactor through a pump, setting the reaction temperature of the microchannel reactor to be 140 ℃, setting the reaction time to be 4 hours, and naturally cooling the mixture to room temperature to obtain a reaction product;

Example 7

A preparation method of a platinum-carbon catalyst comprises the following steps: step 1, dissolving 5g of Vulcan XC-72 and 20g of chloroplatinic acid hexahydrate in 400mL of deionized water, adding 50mL of ethylene glycol and 65g of EDTA, fully stirring and uniformly mixing, and dropwise adding sodium hydroxide to adjust the pH value to 10;

step 2, pumping the mixed solution obtained in the step 1 into a microchannel reactor through a pump, setting the reaction temperature of the microchannel reactor to be 150 ℃, setting the reaction time to be 5 hours, and naturally cooling the mixture to room temperature to obtain a reaction product;

and 3, washing and filter-pressing the reaction product, and drying the filter residue in a forced air drying oven, wherein the temperature of the drying oven is set to 70 ℃, and finally obtaining black catalyst powder.

Example 8

step 1, dissolving 5g of Vulcan XC-72 and 21.5g of chloroplatinic acid hexahydrate in 400mL of deionized water, adding 60mL of ethylene glycol and 73g of EDTA, fully stirring and uniformly mixing, and dropwise adding sodium hydroxide to adjust the pH value to 10;

Example 9

step 1, dissolving 5g of Vulcan XC-72 and 21.5g of chloroplatinic acid hexahydrate in 400mL of deionized water, adding 65mL of ethylene glycol and 220g of EDTA, fully stirring and uniformly mixing, and dropwise adding sodium hydroxide to adjust the pH value to 10;

Comparative example

This comparative example provides a commercial platinum carbon catalyst, purchased from the Zhuangxinwan corporation.

Specifically, the result of XRD test on the platinum-carbon catalyst prepared in example 2 of the present invention is shown in fig. 2, and it can be seen that a characteristic diffraction peak of platinum appears in the spectrum, which indicates that the platinum catalyst successfully prepared in example 2 of the present invention, and the particle size of the platinum catalyst prepared in example 2 of the present invention is 3nm calculated according to the scherrer equation;

the result of CV electrochemical test of the platinum catalyst prepared in example 2 of the present invention is shown in fig. 3, which shows that the CV curve area of the platinum catalyst prepared in example 2 of the present invention by using the microchannel reactor is substantially equal to the CV curve area of the commercial platinum-carbon catalyst, indicating that the platinum catalyst has high electrochemical activity.

Finally, it should be noted that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to examples, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.

Claims

1. The preparation method of the platinum-carbon catalyst is characterized by comprising the following steps of:

2. The method for preparing a platinum-carbon catalyst according to claim 1,

in the step 1, the carbon material is selected from one or more of Ketjen black, Vulcan XC-72, graphene, carbon nanotubes and carbon fibers.

3. The method for preparing a platinum-carbon catalyst according to claim 1,

in the step 1, the polyalcohol is selected from one or more of n-propanol, isopropanol and ethylene glycol;

the ratio of water to polyol is 3-15 in parts by volume.

4. The method for preparing a platinum-carbon catalyst according to claim 1,

in the step 1, the protective agent is selected from one or more of ethylenediamine tetraacetic acid, potassium sodium tartrate, dithizone, ammonium citrate and 8-hydroxyquinoline;

the molar ratio of the protective agent to the chloroplatinic acid hexahydrate is 5-15.

5. The method for preparing a platinum-carbon catalyst according to claim 1,

in the step 1, the alkali is selected from one or more of inorganic alkalis;

the inorganic alkali is selected from one or more of ammonia water, sodium carbonate and sodium hydroxide.

6. The method for preparing a platinum-carbon catalyst according to claim 1,

in the step 2, the reaction temperature of the microchannel reactor is 120-180 ℃, and the reaction time is 1-8 h.

7. The method for preparing a platinum-carbon catalyst according to claim 1,

in the step 3, the drying temperature of the oven is 60-80 ℃.

8. The method for preparing a platinum-carbon catalyst according to any one of claims 1 to 8,

in the step 1, the mixed solution comprises the following components in part by weight:

the ratio of water to the polyhydric alcohol is 6-12 in parts by volume;

the pH value of the mixed solution is 8-12;

9. A platinum carbon catalyst prepared by the preparation method of any one of claims 1 to 9.