KR101310372B1 - Pt-Pd ALLOY PRECURSOR FOR FUEL CELL ELECTRODE CATALYST AND METHOD OF LAW Pt CATALYST USING SAME - Google Patents

Abstract

The present invention relates to a method for producing a Pt-Pd alloy low platinum electrode catalyst for a fuel cell, to prepare a precursor by synthesizing and mixing platinum and palladium in a basic form on a high crystalline carbon support such as carbon fiber, carbon nanotube or carbon black. After that, the present invention relates to a method for producing a low platinum electrode catalyst for a fuel cell, which is prepared through a single supporting step using the precursor.

Description

Pt-Pd ALLOY PRECURSOR FOR FUEL CELL ELECTRODE CATALYST AND METHOD OF LAW Pt CATALYST USING SAME}

The present invention relates to a method for producing a Pt-Pd alloy low platinum electrode catalyst of a fuel cell electrode catalyst, and more particularly, to synthesize a Pt-Pd mixed precursor in a basic form, and to use it to form a highly dispersible and highly crystalline Pt-Pd. It relates to a method for producing an alloy catalyst in one manufacturing process.

A fuel cell is a high efficiency, pollution-free power generation device that directly converts chemical energy of a reactant into electrical energy. It is currently used in household power plants or electric vehicles, and is also used in various fields such as industrial and military use. Fuel cells are classified into molten carbonate fuel cells, solid oxide fuel cells, alkali fuel cells, phosphoric acid fuel cells, polymer electrolyte fuel cells, and direct methanol fuel cells according to electrolytes, operating temperatures, and types of fuels. Among these fuel cells, the polymer electrolyte fuel cell has excellent energy conversion efficiency and high current density even at low temperature, so that development for various fields is being actively conducted.

The performance of a polymer electrolyte fuel cell is largely determined by the performance of a membrane positive electrode catalyst of a fuel cell, and platinum (Pt), which is one of its raw materials, has a great effect on the cost of a fuel cell because the price is very expensive. Accordingly, in order to improve fuel cell performance and reduce cost, many researches and developments of catalysts have been made.

In order to increase the activity of fuel cell catalysts, research has been conducted to manufacture platinum in nano size and to support platinum in high dispersion and high ratio on carbon having high surface area. As such a platinum / support catalyst, an impregnation method using hydrogen, a reducing agent, or the like is commonly used. In addition, research is being conducted using alloys with other metals to reduce the content of platinum, which accounts for most of the fuel costs.

In order to improve the electrode performance by adding transition metals to platinum, alloying ruthenium or iron with platinum is used as a catalyst (European Patent No. 84303984), or alloying three components of platinum-iron-cobalt as a catalyst ( British Patent No. 861599) and the prior art.

The present invention is to provide a Pt-Pd synthetic precursor for a fuel cell catalyst and a method for producing a low platinum catalyst using the same, which improves the performance of a fuel cell, reduces costs, and enables mass production in a simple process.

It proposes a low platinum fuel cell catalyst that replaces the platinum catalyst of fuel cell with inexpensive unit price palladium (Pd) to reduce the cost of the catalyst and maintain the performance similar to that of pure platinum catalyst. Unlike the method, it is an object of the present invention to propose a method of manufacturing a Pt-Pd alloy catalyst in one step, so that a fuel cell catalyst having excellent performance can be mass produced at low cost.

The present invention provides a Pt-Pd heteronuclear complex (hereinafter, 'precursor 2') synthesized using a Pt-Pd mixed solution (hereinafter, 'precursor 1') and a ligand synthesized by mixing Pt-acetate and Pt-amide, respectively. ') And these precursors are used to prepare a highly dispersed, highly crystalline Pt-Pd synthesis catalyst in one step.

The present invention consists of a precursor manufacturing step of synthesizing a Pt-Pd alloy precursor to enable the production of a catalyst by only one manufacturing process and a catalyst manufacturing step of preparing a catalyst for a fuel cell using the precursor.

Precursor manufacturing steps are different in precursors 1 and 2.

In the preparation of precursor 1, an excess of acetic acid is added to palladium to cause a reaction at high temperature to produce palladium-acetate, and platinum and an amine-based organic compound are reacted to prepare platinum-amide (Pt-Amide). Mixing the synthesized solution. By the above method, precursor 1, which is a Pt-Pd mixed solution containing no chlorine (Cl), is prepared.

Preparation of precursor 2 is by the method of synthesizing Pt-Pd dinuclease using ligand. The ligand reacts diethyl malonate with carbon disulfide (CS ₂ ) to synthesize a ketene mercaptal salt, and reacts the synthetic material with an alkyl halide (Alkyl halide), followed by B _a Cl _{It is} prepared by synthesizing with ₂ . Pt (SO ₄ ) (Me ₄ en) is combined with the synthesized ligand to form a Pt complex, and Pd (NO ₃ ) ₂ (Me ₄ en) is bonded to Pt-Barium bis (ethylthio) methylenepropanedioato-Pd- NO ₃ (Hereinafter referred to as' Pt-BETMP-Pd-NO ₃ ). In the above method, Pt-Pd dinuclear complex compound 2 was prepared.

The catalyst is prepared by a method of supporting precursor 1 or precursor 2 on a highly crystalline carbon carrier such as carbon fiber, carbon nanotube, carbon black, or the like. Specifically, the carrier dispersion step of mixing and dispersing the carrier in a solvent; Precursor dispersion step of mixing and dispersing precursor 1 or precursor 2 in a solvent in which the carrier is dispersed; Stabilizing step of adding an acid solution to the mixture passed through the precursor dispersion step; And a post-treatment step of heating and drying the catalyst carrier obtained by filtering and washing the mixture that has undergone the stabilization step. In the case of a conventional alloying catalyst, the above supporting process should be repeated twice, but the catalyst preparation process can be shortened by using the precursor of the present invention.

In the carrier dispersion step, 150 parts by weight of ethylene glycol is mixed with 1 part of the carrier, and a disperser and an ultrasonic device are simultaneously applied to disperse the ethylene cliple on the carrier, and the carrier is carbon fiber or carbon. It is preferred to select from the group consisting of nanotubes and carbon black.

In the precursor dispersing step, the precursor 1 or precursor 2 is added to the mixture that has passed through the carrier dispersing step and stirred for 1 hour, and then stirred for 3 hours while being heated to a temperature of 150 to 170 ° C.

In the stabilization step, it is preferable that the acid solution is added to the mixture through the precursor dispersion step to adjust the pH of the mixture to 2 to 5, and the acid solution is a group consisting of sulfuric acid, nitric acid or acetic acid having a 0.5 molar concentration. More preferably, it is made of one selected from.

In the post-treatment step, the unreacted catalyst component and the acid solution are filtered using a reduced pressure filter of the mixture that has passed the stabilization step, and the remaining solution buried on the surface of the separated catalyst carrier is washed three to five times with distilled water. step; And drying the washed catalyst carrier by heating at 80 to 140 ° C. for 2 to 8 hours using an oven filled with nitrogen.

The method of manufacturing a low platinum electrode catalyst for fuel cells according to the present invention has the effect of replacing platinum with inexpensive palladium and manufacturing the electrode catalyst in one step using a Pt-Pd synthetic precursor to significantly reduce the manufacturing cost. . In addition, by using a precursor that does not contain chlorine, the durability and performance of the membrane electrode assembly are improved, and Pt-Pd dinucleide is used as a precursor, and thus it is easy to control the composition ratio of the catalyst and the particle size. This improves fuel cell performance and extends lifespan.

1 is a flow chart showing a method for producing precursor 1 and precursor 2 according to the present invention,
2 is a flowchart illustrating a method of manufacturing an electrode catalyst for a fuel cell according to the present invention;
3 is an X-ray crystal structure of Pt-Pd dinuclear complex (precursor 2) prepared in Example 2 of the present invention,
4 is a photograph taken by TEM of the dispersion degree of the electrode catalyst for a fuel cell manufactured according to Examples 1, 2 and Comparative Examples of the present invention,
Figure 5 is a graph showing the XRD results of the electrode catalyst for fuel cells produced through Examples 1, 2 and Comparative Examples of the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the scope of the present invention is not limited thereto.

≪ Example 1 >

1. Synthesis of Precursor 1

Pd-nitate precursor and excess acetic acid were mixed and stirred at 80 ° C. for more than 3 to 8 hours to synthesize Pd-acetate precursors. Pt-chloride and mono Ethanolamine (monoethanolamine) was reacted at a temperature of 160 ℃ to synthesize a platinum-amide (Pt-amide) precursor.

Synthesized Pd-acetate and Pt-amide were added to the stirrer and stirred for 1 hour or more to prepare Pt-Pd alloy precursor 1.

2. Preparation of Electrocatalyst

1 part by weight of carbon black and 300 parts by weight of ethylene glycol were added, and the mixture was stirred for 1 hour, and the disperser (Homogenizer) and the high frequency device (sonic bath, Sonic bath) were treated for 4 hours, and the carbon black was dispersed in ethylene glycol. I was.

The amount of precursor 1 calculated to be about 70% supported on the carbon black carrier was added and stirred for 2 hours at a size of 3.5G using a stirrer, followed by heating at a temperature of 160 ° C. for 3 hours at a size of 3.5G. It stirred by heating.

After the mixture was cooled to room temperature, sulfuric acid was added to the mixture to adjust the pH of the mixture to 4, followed by stirring for 8 hours.

The stirred mixture was separated into a catalyst and a filtrate through filtration equipment, and the filtrate remaining on the surface of the separated catalyst was removed by washing 3 to 5 times with distilled water. The washed catalyst carrier was heated for 6 hours at a temperature of 120 ° C. using an oven filled with nitrogen to prepare a Pt-Pd alloy electrode catalyst for a fuel cell.

Example 2

1. Synthesis of Precursor 2

40 g of ethyl malonate and 19 ml of carbon disulfide were added to a mixed solution of 300 ml of dioxane and 200 ml of ethyl ether, and reacted at room temperature for 1 to 2 hours to obtain a yellow acid ketene mercaptal salt. A dipotassium salt obtained by substituting the ketenemecaptal salt with an alkyl halide was dissolved in 400 ml of distilled water, and then reacted with 7.33 g of BaCl ₂ · 2H ₂ O for 1 hour to obtain a ligand (BETMP).

The ligand was dissolved in 400 ml of distilled water, Pt (SO ₄ ) Me ₄ en was added to the equivalent weight, and reacted at 80 ° C. for 3 hours to synthesize a Pt complex.

After dissolving the synthesized Pt complex in 400ml of distilled water, Pd (NO ₃ ) ₂ Me ₄ en was added to the equivalent amount and reacted at 80 ° C. for 3 hours to synthesize Pt-Pd dinuclear complex precursor 2.

2. Preparation of Electrocatalyst

In the same manner as in Example 1, precursor 2 was supported on a carrier to prepare a Pt-Pd-containing electrode catalyst for a fuel cell.

<Comparative Example>

1. Preparation of Pd Electrode Catalyst

1 part by weight of carbon black and 300 parts by weight of ethylene glycol were added, and the mixture was stirred for 1 hour, and the disperser (Homogenizer) and the high frequency device (sonic bath, Sonic bath) were treated for 4 hours, and the carbon black was dispersed in ethylene glycol. I was.

The amount of Pd-nitrate calculated to be about 35% supported on the carbon black carrier was added and stirred for 2 hours at a size of 3.5G using a stirrer, followed by heating at a temperature of 160 ° C. for 3 hours at a size of 3.5G. Stirring while heating.

After the mixture was cooled to room temperature, sulfuric acid was added to the mixture to adjust the pH of the mixture to 4, followed by stirring for 8 hours.

The stirred mixture was separated into a catalyst and a filtrate through filtration equipment, and the filtrate remaining on the surface of the separated catalyst was removed by washing 3 to 5 times with distilled water. The washed catalyst carrier was heated for 6 hours at a temperature of 120 ° C. using an oven filled with nitrogen to prepare a Pd electrode catalyst (Pd / C electrode catalyst).

1. Preparation of Pt-Pd Alloy Electrode Catalyst

The calculated amount of Pt-amide was added to the prepared Pd / C electrode catalyst so as to support about 35%, and the mixture was heated and stirred for 3 hours at a temperature of 150 to 170 ° C.

After the mixture was cooled to room temperature, sulfuric acid was added to the mixture to adjust the pH of the mixture to 4, followed by stirring for 8 hours.

The stirred mixture was separated into a catalyst and a filtrate through filtration equipment, and the filtrate remaining on the surface of the separated catalyst was removed by washing 3 to 5 times with distilled water. The washed catalyst carrier was heated at a temperature of 120 ° C. for 6 hours using an oven filled with nitrogen to prepare a Pt-Pd electrode catalyst.

<Result of Comparative Experiment, etc.>

1. Comparison of Platinum Dispersion

Platinum dispersion of the Pt-Pd alloy electrode catalyst for fuel cells prepared according to Examples 1, 2 and Comparative Examples was photographed and compared with a TEM (Transmission Electron Microscope).

As shown in FIG. 4, the fuel cell electrode catalyst prepared in one step according to the embodiment of the present invention shows that the crystallinity of the metal particles is very excellent compared to the fuel cell electrode catalyst prepared in two steps by the comparative example. Could.

2. Comparison of Metal Particle Size

The particle size of the metal particles of the Pt-Pd alloy electrocatalyst for fuel blocking prepared according to Examples 1 and 2 and Comparative Examples was measured by XRD (X-Ray Diffraction).

As shown in FIG. 5, the average particle size of the Pt-Pd alloy electrode catalyst for fuel cells prepared through Example 1 of the present invention is 3.45 nm, which is the average particle size of the Pt-Pd alloy electrode catalyst for fuel cells prepared through the comparative example. It was smaller than 4.3nm, especially the catalyst particles prepared in Example 1 was confirmed that the XRD peak is sharply formed, the crystallinity is high.

Claims (6)

delete A precursor manufacturing step of preparing a precursor synthesized with platinum and palladium; And
And a catalyst manufacturing step of preparing a catalyst for a fuel cell using the precursor.
The precursor manufacturing step is a catalyst manufacturing method for a fuel cell, characterized in that to prepare and mix the basic form of palladium solution and platinum solution.
A precursor manufacturing step of preparing a precursor synthesized with platinum and palladium; And
And a catalyst manufacturing step of preparing a catalyst for a fuel cell using the precursor.
The precursor manufacturing step comprises the steps of reacting palladium and acetic acid at a high temperature to produce palladium-acetate;
Reacting platinum with an amine organic material to produce platinum-amide; And
Mixing the palladium-acetate and platinum-amide; Fuel cell catalyst manufacturing method comprising a.
A precursor manufacturing step of preparing a precursor synthesized with platinum and palladium; And
And a catalyst manufacturing step of preparing a catalyst for a fuel cell using the precursor.
The precursor manufacturing step comprises the steps of reacting diethyl malonate and carbon disulfide to synthesize a ketenmecaptal salt;
Reacting the ketenemecaptal salt with an alkyl halide and then synthesizing a ligand by synthesizing B ₂ Cl ₂ ;
Combining the ligand with Pt (SO ₄ ) Me ₄ en to synthesize a Pt complex; And
Preparing a Pt-Pd dinuclear complex compound by combining the Pt complex compound and Pd (NO ₃ ) ₂ Me ₄ en;
5. The method according to any one of claims 2 to 4,
The catalyst manufacturing step includes a carrier dispersion step of mixing and dispersing the carrier in a solvent;
Precursor dispersion step of mixing and dispersing precursor 1 or precursor 2 in a solvent in which the carrier is dispersed;
Stabilizing step of adding an acid solution to the mixture passed through the precursor dispersion step; And
And a post-treatment step of heating and drying the catalyst carrier obtained by filtration and washing the mixture which has passed the stabilization step.
Pt-Pd dinuclear complex prepared by the method according to claim 3.

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