阅读说明：本技术 质子交换膜燃料电池用催化剂的制备工艺 (Preparation process of catalyst for proton exchange membrane fuel cell ) 是由 钟发平 符长平 戴超华 王玲 于 2019-09-29 设计创作，主要内容包括：本发明提供了一种质子交换膜燃料电池用催化剂的制备工艺,经活性碳的强化活化处理——铂颗粒的还原负载——联合提纯——干燥——多级破碎——热处理后制得质子交换膜燃料电池用催化剂。本发明方法工艺简单,有效提高其制备得到的质子交换膜燃料电池用催化剂的铂颗粒负载均匀性,提高质子交换膜燃料电池用催化剂的有效利用率,使用本发明制备得到的质子交换膜燃料电池用催化剂,具有高活性、高纯度、高分散性的特点。(The invention provides a preparation process of a catalyst for a proton exchange membrane fuel cell, which is prepared by the steps of strengthening and activating treatment of activated carbon, reduction loading of platinum particles, combined purification, drying, multistage crushing and heat treatment. The method has simple process, effectively improves the platinum particle loading uniformity of the catalyst for the proton exchange membrane fuel cell prepared by the method, and improves the effective utilization rate of the catalyst for the proton exchange membrane fuel cell.)

1. A preparation process of a catalyst for a proton exchange membrane fuel cell is characterized by comprising the following steps: the method comprises the following steps:

(a) immersing activated carbon powder in the acid mixed solution, placing the activated carbon powder in a constant-temperature water bath kettle with the temperature of 60-80 ℃ and a condensation reflux pipe for stirring for 4-10 h, and then washing and filtering the treated substance to obtain an activated carbon filter cake; crushing the activated carbon filter cake to obtain activated carbon fine powder, placing the activated carbon fine powder in a vacuum device continuously filled with mixed gas of hydrogen and argon, preserving heat for a certain time at 200-300 ℃, preserving heat for a certain time at 500-600 ℃, and then cooling to room temperature to prepare the strong activated carbon;

(b) adding a mixed solution of an organic solvent and deionized water into the strongly activated carbon prepared in the step (a), stirring and dispersing to obtain activated carbon slurry, continuously introducing nitrogen or inert gas into the activated carbon slurry, sequentially adding a platinum salt solution and a complexing agent to form mixed slurry, placing the mixed slurry into a constant-temperature water bath kettle with the temperature of 50-70 ℃ and a condensation reflux pipe, stirring for 4-8 hours, cooling to room temperature, adding a reducing agent into the mixed slurry, stirring for 12-24 hours, adding deionized water, and standing to obtain a solid-liquid mixture;

(c) adding an organic extracting agent into the solid-liquid mixture prepared in the step (b), performing oscillation extraction, standing to obtain an extracted solid-liquid mixture, adding a mixed solution of an organic solvent and deionized water into the extracted solid-liquid mixture, performing first centrifugation to obtain a first centrifuged product, and adding deionized water into the first centrifuged product to perform second centrifugation to obtain a final centrifuged solid matter;

(d) vacuum drying the final centrifuged solid matter obtained in the step (c) to obtain a blocky solid, ball-milling and crushing the blocky solid to obtain micron-sized particles, and jet-crushing the micron-sized particles to obtain nano-scale powder;

(e) and (d) placing the nano-scale powder obtained in the step (d) in a vacuum device continuously filled with mixed gas of hydrogen and argon for heat treatment, and then cooling to room temperature to obtain the catalyst for the proton exchange membrane fuel cell.

2. The process for preparing a catalyst for a proton exchange membrane fuel cell according to claim 1, wherein: in the step (b), the mass content of the strongly activated carbon in the activated carbon slurry is 1-10%.

3. The process for preparing a catalyst for a proton exchange membrane fuel cell according to claim 1, wherein: in the step (a), the acid mixed solution is formed by mixing any two or three of concentrated nitric acid, concentrated hydrochloric acid and hydrogen peroxide.

4. The process for preparing a catalyst for a proton exchange membrane fuel cell according to claim 1, wherein: in the step (b) and the step (c), the volume ratio of the organic solvent to the deionized water in the mixed solution of the organic solvent and the deionized water is 1: 2 to 5.

5. The process for preparing a catalyst for a proton exchange membrane fuel cell according to claim 4, wherein: .

In the step (a), the volume ratio of hydrogen to argon in the mixed gas of hydrogen and argon is 1: 2-5; in the step (e), the volume ratio of hydrogen to argon in the mixed gas of hydrogen and argon is 1: 3 to 6.

6. The process for preparing a catalyst for a proton exchange membrane fuel cell according to any one of claims 1 to 5, wherein: in the step (d), the specific process for obtaining micron-sized particles by ball milling and crushing comprises the following steps: ball-milling the blocky solid in a ball-milling device, wherein the rotating speed of the ball-milling device is controlled to be 100-300 r/min, and the ball-milling time is controlled to be 5-10 min; the specific process for obtaining the nano-grade powder by jet milling comprises the following steps: the micron-sized particles are placed in a material preparation cavity of an air flow crushing device for crushing, and the air pressure of the air flow crushing device is controlled to be 0.5-4

And (5) controlling the crushing time to be 10-20 min under the MPa.

Technical Field

The invention relates to a preparation method of a catalyst, in particular to a preparation process of a catalyst for a proton exchange membrane fuel cell.

Background

The catalyst used by the proton exchange membrane fuel cell is a heterogeneous and supported noble metal catalyst, and the noble metal used is platinum, palladium, ruthenium, rhodium, silver and the like; the d electron orbits of the catalyst are not filled, the surface of the catalyst is easy to absorb reactants, the strength of the catalyst is moderate, an intermediate active compound is favorably formed, the catalyst has high catalytic activity, and the catalyst also has the comprehensive excellent characteristics of high temperature resistance, oxidation resistance, corrosion resistance and the like.

At present, catalysts used by proton exchange membrane fuel cells are mainly platinum-carbon catalysts, and the preparation methods thereof can be divided into two types: chemical reduction methods and physical methods. Chemical reduction methods are the focus of current research, while physical methods are under constant development.

The chemical reduction method includes a microwave method, a solvent method (also referred to as a precipitation method), a microemulsion method (also referred to as an inverse micelle method), a hydrothermal method, an impregnation method, an ion exchange method, an electrochemical deposition method, an organosol-gel method, a carbonyl compound decomposition method, a solid phase method, and the like.

The traditional preparation method of the catalyst for the proton exchange membrane fuel cell generally adopts a single activation mode to activate the activated carbon, so that the activation degree of the activated carbon is not enough, and the loading effect of the metal platinum is poor. Secondly, the purification after the catalyst synthesis generally adopts common washing filtration, which is not beneficial to the fine separation of impurity elements; and the catalyst is purified and dried from the reaction solution, and then is crushed in a common crushing mode, so that the granularity and the dispersion effect of the granularity cannot be ensured. Therefore, the development of a novel preparation process technology of the catalyst for the proton exchange membrane fuel cell has important significance for promoting the large-scale application of the fuel cell in China.

Disclosure of Invention

The invention aims to provide a preparation process of a catalyst for a proton exchange membrane fuel cell, which is simple in process, and the prepared catalyst for the proton exchange membrane fuel cell has better platinum particle loading uniformity and higher effective utilization rate.

The invention is realized by the following scheme:

a preparation process of a catalyst for a proton exchange membrane fuel cell comprises the following steps:

(a) immersing activated carbon powder in the acid mixed solution, placing the activated carbon powder in a constant-temperature water bath kettle with the temperature of 60-80 ℃ and a condensation reflux pipe for stirring for 4-10 h, and then washing and filtering the treated substance to obtain an activated carbon filter cake; crushing the activated carbon filter cake to obtain activated carbon fine powder, placing the activated carbon fine powder in a vacuum device continuously filled with mixed gas of hydrogen and argon, preserving heat for a certain time at 200-300 ℃, preserving heat for a certain time at 500-600 ℃, and then cooling to room temperature to prepare the strong activated carbon; the temperature is generally kept for more than 1h at 200-300 ℃ and more than 4h at 500-600 ℃ in a vacuum device. The step is reinforced activation treatment of activated carbon, and by combining backflow of strong acid mixed solution with heat treatment of mixed gas, the activated carbon is more loose, larger in porosity and more uniform in pore size and has higher specific surface area, so that the activated carbon has better adsorption activity, reduced nano Pt particles and the like are better and uniformly loaded, the nano Pt particles and the like are effectively utilized, and the electrochemical activity of the catalyst is further enhanced;

(b) adding a mixed solution of an organic solvent and deionized water into the strongly activated carbon prepared in the step (a), stirring and dispersing to obtain activated carbon slurry, generally adopting magnetic stirring or mechanical stirring, generally adopting ultrasonic dispersion, continuously introducing nitrogen or inert gas into the activated carbon slurry, then sequentially adding a platinum salt solution and a complexing agent to form mixed slurry, placing the mixed slurry into a constant-temperature water bath kettle with the temperature of 50-70 ℃ and a condensation reflux pipe for stirring for 4-8 hours, cooling to room temperature, then adding a reducing agent into the mixed slurry, stirring for 12-24 hours, then adding deionized water, and standing to obtain a solid-liquid mixture; the platinum salt solution is a chloroplatinic acid solution, a potassium chloroplatinite solution, a hexahydroxyplatinic acid solution and the like, the complexing agent is trisodium citrate, ethylenediamine, ammonia water and the like, and the reducing agent is ascorbic acid, hydrazine hydrate, sodium borohydride and the like; the step is reduction loading of nano platinum particles;

(c) adding an organic extracting agent into the solid-liquid mixture prepared in the step (b), performing oscillation extraction, standing to obtain an extracted solid-liquid mixture, adding a mixed solution of an organic solvent and deionized water into the extracted solid-liquid mixture, performing first centrifugation to obtain a first centrifuged product, and adding deionized water into the first centrifuged product to perform second centrifugation to obtain a final centrifuged solid matter; the organic extractant is dichloromethane, ethyl acetate, carbon tetrachloride and the like; the product after reaction is washed and separated by adopting a method combining extraction washing and centrifugal separation, and the combined enhanced purification process further enhances the removal effect of impurities and ensures that the residual impurity elements, especially chlorine (Cl), in the catalyst are removed, because the chlorine ions have high electrophilicity and can influence the adsorption and activation of hydrogen on the metal ions if the chlorine ions exist; the step is combined enhanced purification;

(d) vacuum drying the final centrifuged solid matter obtained in the step (c) to obtain a blocky solid, ball-milling and crushing the blocky solid to obtain micron-sized particles, and jet-crushing the micron-sized particles to obtain nano-scale powder; the step is to improve the crushing process, and to crush the dried blocky solid by a method combining ball milling and jet milling, so as to ensure that the catalyst particles finally reach uniform nanometer level, which is beneficial to the dispersion of catalyst slurry preparation, better plays the activity of the catalyst and achieves the purpose of improving the power of the membrane electrode of the fuel cell; the steps are drying and multistage crushing;

(e) and (d) placing the nano-scale powder obtained in the step (d) in a vacuum device continuously filled with mixed gas of hydrogen and argon for heat treatment, and then cooling to room temperature to obtain the catalyst for the proton exchange membrane fuel cell. During heat treatment, the temperature of the vacuum device is generally controlled to be 300-500 ℃, and the heat preservation time is generally controlled to be 4-6 hours.

The step is a heat treatment.

In the step (b), the mass content of the strongly activated carbon in the activated carbon slurry is 1-10%.

In the step (a), the acid mixed solution is formed by mixing any two or three of concentrated nitric acid, concentrated hydrochloric acid and hydrogen peroxide.

In the step (b) and the step (c), the volume ratio of the organic solvent to the deionized water in the mixed solution of the organic solvent and the deionized water is 1: 2 to 5. The organic solvent is typically isopropanol, ethanol, ethylene glycol, or the like.

In the step (a), the volume ratio of hydrogen to argon in the mixed gas of hydrogen and argon is 1: 2-5; in the step (e), the volume ratio of hydrogen to argon in the mixed gas of hydrogen and argon is 1: 3 to 6.

In the step (d), the specific process for obtaining micron-sized particles by ball milling and crushing comprises the following steps: ball-milling the blocky solid in a ball-milling device, wherein the rotating speed of the ball-milling device is controlled to be 100-300 r/min, and the ball-milling time is controlled to be 5-10 min; the specific process for obtaining the nano-grade powder by jet milling comprises the following steps: and (3) placing the micron-sized particles into a material preparation cavity of an airflow crushing device for crushing, wherein the air pressure of the airflow crushing device is controlled to be 0.5-4 MPa, and the crushing time is controlled to be 10-20 min.

In the step (a), the specific process for obtaining the activated carbon fine powder by crushing the activated carbon filter cake comprises the following steps: and placing the activated carbon filter cake into a ball milling device for ball milling, wherein the rotating speed of the ball milling device is controlled to be 200-600 r/min, and the ball milling time is controlled to be 5-10 min.

In the step (c), the concrete process of shaking extraction is as follows: placing the container filled with the solid-liquid mixture and the organic extractant on a water bath constant temperature oscillator for oscillation extraction, wherein the oscillation frequency of the water bath constant temperature oscillator is 120-150 Hz, the oscillation time is controlled to be 5-10 min, pouring the upper-layer solution after standing and layering, and repeating the steps for 3-5 times to obtain the extracted solid-liquid mixture at the lower layer; the specific process of the first centrifugal treatment comprises the following steps: adding the extracted solid-liquid mixture into a centrifugal bottle, adding a mixed solution of an organic solvent and deionized water into the centrifugal bottle for first centrifugation, controlling the rotating speed of the centrifugal bottle to be 1000-2000 r/min, controlling the centrifugation time to be 5-8 min, pouring out supernatant, and repeating the steps for 3-5 times to obtain a product after the first centrifugation; the second centrifugation treatment comprises the following specific processes: and adding deionized water into the product after the first centrifugation for second centrifugation treatment, controlling the rotating speed of a centrifuge bottle to be 2500-3500 r/min, controlling the centrifugation time to be 5-8 min, pouring out the supernatant, and repeating the steps for 3-5 times to obtain the final centrifuged solid matter.

The inert gas is typically argon, helium, or the like. The vacuum device can be selected from a vacuum tube furnace and the like.

The preparation process method of the catalyst for the proton exchange membrane fuel cell is simple in process, firstly, the activated carbon is strengthened and activated by combining strong acid reflux and mixed gas heat treatment, then, a combined strengthening and purifying process combining extraction washing and centrifugal separation is adopted, and finally, a multistage crushing process combining ball milling and airflow crushing is utilized, so that the platinum particle load uniformity of the prepared catalyst for the proton exchange membrane fuel cell can be effectively improved, and the effective utilization rate of the catalyst for the proton exchange membrane fuel cell is improved. The catalyst for the proton exchange membrane fuel cell prepared by the method has the characteristics of high activity, high purity and high dispersibility.

Detailed Description

The present invention will be further described with reference to the following examples, but the present invention is not limited to the description of the examples.