KR101333733B1 - A method for preparing Pt-ZSM-5 - Google Patents

Abstract

The present invention provides a) a platinum source solution, b) adding the platinum source to a zeolite-containing dispersion to prepare a mixture, c) reducing the mixture and filtering to obtain a filtrate, and d) filtering the filtrate. The present invention relates to a method for producing a platinum catalyst supported on a zeolite for a fuel cell, comprising the step of drying. The use of a platinum catalyst that participates in a reaction while minimizing the amount of platinum supported by the production of a catalyst electrode using a zeolite to which platinum is added. It is effective to maximize the degree.

Description

Manufacturing method of zeolite carbon composite electrode {A method for preparing Pt-ZSM-5}

The present invention provides a method for producing a zeolite / carbon composite electrode, specifically, a membrane electrode assembly (MEA) using a platinum catalyst ion exchanged to ZSM-5 (hereinafter Pt-ZSM-5) as a catalyst electrode of a hydrogen fuel cell. The present invention relates to a method for producing an electrode of a PEMFC which generates electricity by using a zeolite loaded with platinum as a catalyst layer and hydrogen at the anode and oxygen at the cathode.

BACKGROUND ART In general, hydrogen ion exchange electrolyte membrane fuel cells (PEMFCs) have high energy conversion efficiency and high electric density, and have almost no emission of pollutants, and thus are attracting much attention as alternative energy conversion devices for fixed and mobile applications. However, it has been pointed out that the long-term stability and the high manufacturing cost of the MEA. The most expensive part of MEA is electrochemical catalyst, and platinum is used as catalyst electrode. Platinum catalysts, however, have been pointed out by their high cost, deactivation and slow reduction in the cathode. The biggest problem is that despite the high loading of Pt, the utilization of platinum in the reaction is very low. Conventional methods for preparing electrodes are mainly used by mixing Pt / C agglomerate with Nafion ionomer solution and coating the porous support using a decal method, a blade method, or a spray method. The catalyst electrode layer prepared by the conventional method is limited to the interface between the polymer electrolyte known as the three phase reaction zone and the platinum catalyst exposed to the reactant, so that an inert catalyst that does not participate in the catalytic reaction exists. There are disadvantages. Recently, a method of depositing very small platinum catalyst particles on the interface between the polymer electrolyte and the electrode has been proposed. In order to minimize the amount of platinum loading and maximize the use of the reaction, it is necessary to maximize the platinum active point participating in the reaction with a small amount of platinum, minimize the thickness of the active layer (less than 25 microns), and minimize the size of the platinum particles supported on carbon. And the like have been proposed. However, since some of the platinum catalyst particles penetrate into the gas diffusion layer (GDL) and the electrolyte membrane, they cannot participate in the electrochemical reaction occurring at the interface between the catalyst layer and the electrolyte membrane. In order to overcome this problem, much research has been conducted on the development of supports such as carbon nanotubes (CNT), carbon nanofibers, porous carbon, fumed silica, and zeolites to support platinum catalysts.

The present invention has been made to solve the above problems and by the necessity of the above, an object of the present invention to provide a platinum catalyst that maximizes the utilization of the platinum catalyst to participate in the reaction while minimizing the amount of platinum.

Another object of the present invention is to provide a method for preparing the platinum catalyst.

Still another object of the present invention is to provide an electrode of a hydrogen ion exchange electrolyte membrane fuel cell using the catalyst.

Still another object of the present invention is to provide a method of manufacturing the electrode.

In order to achieve the above object, the present invention provides a platinum source solution, the platinum source is added to a zeolite-containing dispersion to prepare a mixture, the mixture is reduced and then filtered to obtain a filtrate, and the filtrate is dried Through a method for producing a platinum catalyst supported on a zeolite for fuel cells, comprising depositing a solution containing platinum / carbon, a platinum catalyst supported on a zeolite, and carbon on a gas diffusion substrate, the platinum / carbon and zeolite The weight ratio of the supported platinum catalyst is 5: 5.

In one embodiment of the present invention, the weight ratio of platinum / carbon to Pt-ZSM-5 affects the performance expression of the fuel cell (FIG. 8B). The reason for the addition of platinum / carbon is that zeolite has a very low electrical conductivity, so that the movement of electrons generated by the reduction of hydrogen in the hydrogen electrode is not smooth. do. However, if too much platinum / carbon is added, e.g. above 8: 2, the properties of the zeolite, i.e. the loss of platinum into the previously described GDL layer or membrane, will lead to a decrease in the availability of platinum and thus an equal amount of Platinum loading may result in deterioration of battery performance. As shown in Figure 8b it can be seen that the battery performance is the best when the ratio of Pt / C to Pt-ZSM-5 is 5: 5. On the other hand, if the amount of Pt-zeolite is too large, the electrical conductivity is likewise reduced, which may also lead to a decrease in battery performance. In FIG. 8B, when comparing Y2 (Pt / C: Pt / Z = 7: 3) and Y4 (Pt / C: Pt / Z = 4: 6), it can be seen that Y4 has excellent performance at high current density. The reason is turned, because if the Pt / C number of Pt is supported on the carbon outer surface (in the case of Y4 include a significant amount of Pt present in the zeolite pores), the amount of water to be generated is conducted further the reduction of O ₂ in the cathode rapidly increased This is because mass transfer due to water flooding is not performed smoothly. Therefore, proper use of the weight ratio of platinum / carbon and platinum / zeolite can improve battery performance. Therefore, the weight ratio of the platinum / carbon and the platinum catalyst supported on the zeolite of the present invention is preferably 7: 3 to 4: 6, but is not limited thereto.

In addition, the present invention comprises the steps of a) depositing a solution containing platinum / carbon on a gas diffusion substrate; And b) depositing a solution comprising a platinum catalyst and carbon supported on the zeolite of claim 5 on the deposited substrate, wherein the platinum catalyst layer and platinum / carbon layer supported on the zeolite are alternately deposited on the gas diffusion substrate. Provided is a method of manufacturing a fuel cell by laminating.

Hereinafter, the present invention will be described.

Most fuel cells utilize copolymers of perfluorinated monomers containing sulfonic acid groups, such as tetrafluoroethylene (TFE) and perfluorosulfonyl fluoride ethoxy propyl vinyl ether (PSEPVE). One such copolymer is NAFION® (E. I. duPont de Nemours and Co., Wilmington, Delaware, USA) available commercially or similarly. These materials are often provided in the form of membranes, eg, non-thermoplastic forms having flat rectangular or square structures for subsequent use, and Nafion is also used in one embodiment of the present invention.

Moreover, when the organic polymer which has a heterocyclic ring like PVP is added to the composition of this invention, it has the effect of reducing the surface roughness of the coating film formed using this composition. Therefore, the coating film surface which has a desired surface roughness can be formed by adjusting the addition ratio of the said organic polymer. The content rate of an organic polymer is selected in the range of 0.1-20 mass% of a metal particle. Among them, although the content differs depending on the kind to be added, the content of the organic polymer is more preferably in the range of 0.2 to 10.0 mass%. The content of the organic polymer is in the range of 0.1 to 20% by mass of the metal particles because the effect of suppressing sintering is not obtained at less than 0.1% by mass, and the adhesion between the formed film and the substrate cannot be sufficiently obtained. It is because when it exceeds mass%, the problem that a specific resistance and a reflectance will fall will fall. Specifically, examples of the copolymer of PVP include PVP-methacrylate copolymer, PVP-styrene copolymer, PVP-vinyl acetate copolymer and the like. Examples of the cellulose ether include hydroxypropylmethylcellulose, methylcellulose, and hydroxyethylmethylcellulose.

The present invention relates to a method of maximizing the utilization of a platinum catalyst participating in the reaction while minimizing the amount of platinum supported by directly supporting platinum on zeolite. Further, the advantages of the method of supporting the zeolite on the electrode for PEMFC, as described above, is to minimize the amount of platinum and reduce the loss of platinum by supporting the platinum in the pores in the zeolite as well as the surface of the zeolite. However, as is known, carbon is an excellent electrical conductivity while zeolite is an electrical insulator. Therefore, zeolite alone cannot be used as a catalyst support and a zeolite / carbon composite must be used to express catalytic activity and electrical conductivity. In addition, since the zeolite has a relatively low skeleton density, a slight increase in the thickness of the zeolite / platinum catalyst layer is inevitable to support a predetermined amount of platinum. Therefore, in the present invention, the platinum-supported zeolite and platinum-supported carbon are used for the preparation of the catalytic electrode, and the platinum-supported zeolite / carbon composite catalyst layer and the platinum-supported zeolite layer and the platinum-supported carbon layer are alternately coated. The present invention relates to a method for producing a catalytic electrode using a zeolite to which platinum is added by manufacturing an electrode manufactured by the present invention.

The present invention will be described in more detail as follows.

In preparing the ZSM-5 of the present invention, various types of organic materials

It has been used as a template for. So far, tetrapropyl ammonium cation has been known to have the best template effect among the organic materials known to be effective in forming the structure of ZSM-5, and in fact, most commercially available ZSM-5 is synthesized using the above materials. However, although tetrapropyl ammonium is a material that exhibits good template effects, studies have been attempted to exclude the use of other organic materials, including these, as templates, and several processes have been developed. On the other hand, the reason for excluding the organic template is the first reason that the price of such a material is very expensive and the toxicity is so strong that the risk of environmental pollution is high. In the synthesis of ZSM-5 using organic templates, secondary costs associated with the treatment of toxic organics in unreacted materials are essential and the risk of environmental pollution is very high. In addition, the organic material present in the crystal grains of ZSM-5 prepared using the organic material should be calcined at 550 ° C. and pyrolyzed before being used as a catalyst. When pyrolysis does not occur completely during the removal process by calcination, Occlusion of pores can lead to fatal defects in catalytic activity. In addition, the additional cost of calcination and air pollution by the exhaust gas generated during thermal decomposition of organic materials is inevitable. Therefore, in order to overcome the above-mentioned difficulties, Flanigen et al. First reported a method of synthesizing ZSM-5 with or without crystalline species in the absence of organic materials in US Pat. No. 4,257,885 (1981). However, this method has a very long reaction time of 68 to 120 hours.

Kuhl's U.S. Pat.No. 4,565,681 (1986) discloses a process for synthesizing ZSM-5 under organic template exclusion for 8 to 48 hours at 150-200 ° C. by mixing a silica source with an acid treated alumina source. have. Klocke also proposed a method for synthesizing ZSM-5 under organic template exclusion from silica precursors neutralized with sulfuric acid in US Pat. No. 5,240,892 (1993). However, according to the method disclosed in the above document, even though the reaction was performed at a relatively high temperature of 220 ° C. by adding crystal species that promote crystallization, there is a disadvantage that the crystallinity is only up to about 75%. Therefore, with respect to the method for synthesizing the ZSM-5 of the present invention, it is preferable to prepare by the method described in the Republic of Korea Patent No. 10-0528672 of the inventor of the present invention.

In this regard, a summary of the method for synthesizing ZSM-5 under the exclusion of organic templates reported so far is to neutralize the alumina source by using crystal species that promote crystallization or by adding acid solution to form a suitable gel precursor.

Has been applied, and the reaction time is generally long. The method described in Korean Patent No. 10-0528672 is a two-step variable temperature process in which a reaction mixture for preparing ZSM-5, which does not use an organic template and crystalline species, is nucleated at a relatively high temperature and then crystallized at a relatively low temperature. The present invention relates to a method for preparing ZSM-5 having a crystallinity of substantially 100%, free of control of crystal size and particle size distribution, and free of impurities. The size of crystals is reduced without using organic templates and crystal species. Crystal size while adjusting freely

ZSM-5, which has a uniform distribution and high crystallinity, is composed of silica source, alkali metal oxide source, alumina source and water, and M2O / SiO2 0.07 ~ 0.14, H2O / SiO2 15 ~ 42, and SiO2 / Al2O3 on a molar basis. Providing a reaction mixture having a composition of 20 to 100, wherein M is an alkali metal ion; Nucleating by maintaining the reaction mixture at a temperature of 180 to 210 ° C. for a controlled time within a range of 2 to 20 hours depending on the crystal size and particle size distribution of ZSM-5 to be prepared; And maintaining the nucleated reactant at 130 to 170 ° C. for 10 to 200 hours for crystallization reaction. According to one preferred embodiment of the method described in Korean Patent No. 10-0528672, providing a first aqueous solution in which a silica source, an alkali metal oxide source and water are mixed; an agent that mixes an alumina source, an alkali metal oxide source and water Providing 2 aqueous solution; The first aqueous solution and the second aqueous solution are mixed, but optionally, further water is added to have a composition range of M 2 O / SiO 2 0.07 to 0.14, H 2 O / SiO 2 15 to 42, and SiO 2 / Al 2 O 3 20 to 100. Providing a mixture; Nucleating by maintaining the reaction mixture at a temperature of 180 to 210 ° C. for a controlled time within a range of 2 to 20 hours depending on the crystal size and particle size distribution of ZSM-5 to be prepared; And maintaining the nucleated reactant at 130 to 170 ° C. for 10 to 200 hours for crystallization reaction. For other specific manufacturing methods, see Examples of Korean Patent No. 10-0528672.

As can be seen through the description of the present specification, in the present invention, a platinum-supported zeolite / carbon composite catalyst layer and a platinum-supported zeolite layer are used in the production of a catalyst electrode using platinum-supported zeolite and platinum-supported carbon. By manufacturing an electrode prepared by alternately coating a carbon layer carrying platinum and platinum, a catalyst electrode can be prepared using a zeolite to which platinum is added, thereby maximizing the utilization of the platinum catalyst participating in the reaction while minimizing the supporting amount of platinum. It is effective to let.

FIG. 1A is an XRD pattern for platinum according to Example 1, and FIG. 1B is a TEM (Transmission Electron Micrograph) of the obtained product. The size of platinum is analyzed and FIG. 1C is a distribution of platinum sizes.
Figure 2a is an XRD pattern for platinum according to Example 2, Figure 2b was analyzed the size of the platinum in the transmission electron micrograph (TEM) for the obtained product, Figure 2c is a distribution of platinum size.
Figure 3a is an XRD pattern for platinum according to Example 3, Figure 3b was analyzed the size of the platinum in the transmission electron micrograph (TEM) for the obtained product, Figure 3c is a distribution of the platinum size.
Figure 4a is an XRD pattern for the platinum according to Example 4, Figure 4b was analyzed the size of the platinum in the transmission electron micrograph (TEM) for the obtained product, Figure 4c is a distribution of platinum size.
FIG. 5A is an XRD pattern for platinum according to Example 5, and FIG. 5B is a transmission electron micrograph (TEM) of the obtained product. The size of platinum is analyzed, and FIG. 5C is a distribution of platinum sizes.
FIG. 6A is a diagram showing a diagram of an alternate catalyst layer electrode according to Example 6, and FIG. 6B is a diagram showing cell performance of an MEA prepared by using the alternate catalyst layer electrode shown in FIG. 6A as an anode. In FIG. 6B, GCZC stands for Gas diffusion layer-Carbon-Zeolite Catalyst, and GCZC1 uses Pt-ZSM-5 prepared in Example 1 to prepare platinum, carbon, and Pt-ZSM- in the gas diffusion layer. 5 is an electrode made by layering sequentially, GCZC4 is a Pt-ZSM-5 prepared in Example 4, when manufacturing the electrode, platinum / carbon, Pt-ZSM-5 layer sequentially in the gas diffusion layer The electrode is made to make. In addition, the details of commercial platinum / carbon used as Commercial is "BASF Fuel Cell Inc., 40% Pt on Vulcan XC-72".
FIG. 7A is a schematic diagram of a composite membrane prepared according to Example 7 and FIG. 7B is a cell performance result for the MEA prepared using the same. In FIG. 7, COMP is an abbreviation of Composite, and COMP1 uses Pt-ZSM-5 manufactured in Example 1 to mix platinum / carbon and Pt-ZSM-5 in the gas diffusion layer at the time of manufacturing the electrode. The electrode is a catalyst layer electrode made of the mixture, COMP2 is prepared using the Pt-ZSM-5 prepared in Example 2, when the electrode is prepared, by mixing the platinum / carbon, Pt-ZSM-5 in the gas diffusion layer to prepare the ink The electrode is a catalyst layer made of a mixture made, COMP3 is prepared by using Pt-ZSM-5 prepared in Example 3, when the electrode is prepared, the platinum diffusion of carbon / carbon, Pt-ZSM-5 in the gas diffusion layer is mixed The electrode is a catalyst layer electrode made of the mixture, COMP4 is prepared by using the Pt-ZSM-5 prepared in Example 4, when the electrode is prepared, the platinum diffusion of carbon / carbon, Pt-ZSM-5 in the gas diffusion layer to prepare the ink It is an electrode layered with a catalyst mixture. Examples 1, 2, 3, and 4 are methods for preparing Pt-ZSM-5 in a liquid phase, and Example 5 are methods for preparing Pt-ZSM-5 in a gas phase. Examples 1, 2, 3, and 4 are gas phases. There is no manufacturing method. It is carried out to compare the case prepared by the liquid phase and the gas phase. In addition, the details of commercial platinum / carbon used as Commercial is "BASF Fuel Cell Inc., 40% Pt on Vulcan XC-72".
8A is the result of MEA prepared according to Example 8. FIG. 8B is a table showing the weight of ZSM-5 in the catalyst.
(A), (b) and (c) are SEM cross-sectional images of the anode for the composite catalyst layer, (d) and (e) are the cross-sectional pictures of the alternate catalyst layer, and (f) is commercial Pt / C. A cross-sectional picture of the anode manufactured by

Hereinafter, the present invention will be described in more detail by way of non-limiting examples. However, the following examples are intended to illustrate the present invention and the scope of the present invention is not to be construed as limited by the following examples.

Example 1:

0.2 g of Pt (NH ₃ ) ₄ Cl ₂ (Aldrich) was added to Beaker 1 to make a solution. 1.2 g of ZSM-5 was added thereto and stirred at 250 rpm for 12 hours at 60 ° C. Polyvinylpyrrolidone having a molecular weight of 10,000 g of 12 g in 1000 g of a solution of ethanol and water 3: 1 mixed in beaker 2 (Hereinafter referred to as PVP, Mol. Wt. 10,000, TCI) was mixed at 60 ° C. The solution stirred in beaker 1 was added to beaker 2, and NaBH ₄ as a reducing agent was added at a ratio of 1: 4 based on the molar ratio of Pt (NH ₃ ) ₄ Cl ₂ and NaBH ₄ and stirred at 60 ° C. for 3 hours. The product of Beaker 2 was filtered off using a membrane filter having a pore size of 0.2 μm, filtered sufficiently with distilled water, dried at 100 ° C. for 10 hours, and then calcined at 500 ° C. for 5 hours as summarized in Table 1. It was. The product was confirmed by XRD analysis in order to determine whether platinum was formed, and it was confirmed that the platinum loading was 9.906 wt% through ICP measurement. 1-a is the XRD pattern for platinum and 1-b is the size of platinum in the transmission electron micrograph (TEM) of the obtained product, and 1-c is the distribution of platinum size.

Example 2:

0.2 g of Pt (NH ₃ ) ₄ Cl ₂ was added to the beaker 1, and 20 g of water was rotted to prepare a solution. 1.2 g of ZSM-5 was added thereto and stirred at 250 rpm for 12 hours at 60 ° C. To 1000 g of a solution in which beaker 2 was mixed with ethanol and water 9: 1, PVP having a molecular weight of 10,000 g of 12 g was mixed at 60 ° C. The stirred solution in beaker 1 was added to beaker 2, and NaBH ₄ , a reducing agent, was added at a 5: 1 molar ratio of Pt (NH ₃ ) ₄ Cl ₂ and NaBH ₄ , followed by stirring at 60 ° C. for 3 hours. The product of Beaker 2 was filtered off using a membrane filter having a pore size of 0.2 μm, filtered sufficiently with distilled water, dried at 100 ° C. for 10 hours, and then calcined at 500 ° C. for 5 hours as summarized in Table 1. It was. The product was confirmed by XRD analysis to determine whether platinum was formed, and the amount of platinum loaded was 7.304 wt% through ICP measurement. 2-a is the XRD pattern for platinum and 2-b is the size of platinum in the transmission electron micrograph (TEM) of the obtained product, and 2-c is the distribution of platinum size.

Example 3:

0.2 g of Pt (NH ₃ ) ₄ Cl ₂ was added to the beaker 1, and 20 g of water was rotted to prepare a solution. 1.2 g of ZSM-5 was added thereto and stirred at 250 rpm for 12 hours at 60 ° C. The beaker 2 was mixed with 250 g of water and 3 g of PVP having a molecular weight of 10,000 at 60 ° C. The stirred solution in beaker 1 was mixed with beaker 2, and the reducing agent NaBH ₄ was mixed with a molar ratio of Pt (NH ₃ ) ₄ Cl ₂ and NaBH ₄ . 5: 1 was added as a reference and stirred at 60 ° C for 3 hours. The product of Beaker 2 was filtered off using a membrane filter having a pore size of 0.2 μm, filtered sufficiently with distilled water, dried at 100 ° C. for 10 hours, and then calcined at 500 ° C. for 5 hours as summarized in Table 1. It was. The product was confirmed by XRD analysis in order to determine whether platinum was formed, and it was confirmed that the platinum loading was 6.685 wt% through ICP measurement. 3-a is the XRD pattern for platinum, 3-b is the size of platinum in the transmission electron micrograph (TEM) of the obtained product, and 3-c is the distribution of platinum size.

Example 4:

0.2 g of platinum cause Pt (NH ₃ ) ₄ Cl ₂ was added to beaker 1, and 20 g of water was added thereto to make a solution. 1.2 g of ZSM-5 was added thereto and stirred at 250 rpm for 12 hours at 60 ° C. To 250 g of a solution of 3: 1 ethanol and water mixed in a beaker 2, PVP having a molecular weight of 10,000 g of 3 g was mixed at 60 ° C. Both the stirred solution and the powder in the beaker 1 were added to the beaker 2, and the reducing agent NaBH4 was added at a mole ratio of 5: 1 moles of NaBH4 to Pt (NH ₃ ) ₄ Cl ₂ at a nitrogen atmosphere at 60 ° C. for 3 hours. Was stirred. The product of Beaker 2 was separated by filtration using a membrane filter having a pore size of 0.2 μm, sufficiently filtered with distilled water, dried at 100 ° C. for 10 hours, and then the powder was nitrogen atmosphere at 500 ° C. for 5 hours as summarized in Table 1. Heated at. The product was confirmed by XRD analysis in order to determine whether platinum was formed, and the amount of platinum loaded was 5.546 wt% through ICP measurement. 4-a is the XRD pattern for platinum and 4-b is the size of platinum in the Transmission Electron Micrograph (TEM) for the resulting product. 4-c is the distribution of platinum size.

Example 5:

0.2 g of Pt (NH ₃ ) ₄ Cl ₂ was added to the beaker 1, and 20 g of water was rotted to prepare a solution. 1.2 g of ZSM-5 was added and stirred at 250 rpm for 24 hours at 60 ° C. The product of beaker 1 was filtered off using a membrane filter having a pore size of 0.2 μm, filtered sufficiently with distilled water, dried at 80 ° C. for 12 hours, and then the powder was dried at 350 ° C. to 0.2 ° C./min as summarized in Table 1. It heated in nitrogen atmosphere at the temperature increase rate. The product was confirmed by XRD analysis to determine whether platinum was formed, and the platinum loading was confirmed to be 9.113 wt% through ICP measurement. 5-a is the XRD pattern for platinum and 5-b is the size of platinum in the Transmission Electron Micrograph (TEM) for the resulting product, and 5-c is the distribution of platinum size.

Table 1 is a table showing the reduction conditions for Pt salt-ZSM-5.

Example 6:

This embodiment relates to the production of alternate catalyst layer electrode (GCZCno: GDL-Carbon-Zeolite-Composite), which is produced by alternately stacking a small amount of carbon-added Pt-ZSM-5 layer and a platinum / carbon layer to GDL. First, GDL (SCCG 5N PLHOS MPL, SEAL) of 3cm x 3cm area was prepared and weighed. In a beaker 1, 0.114 g of commercial platinum / carbon (40% Pt on Vulcan XC-72, BASF Fuel Cell Inc), 1 g of water, 1 g of Nafion (5 wt%), and 100 g of Iso proply alchol (IPA) were mixed in this order. 1 was prepared. In beaker 2, Pt-ZSM-5 (platinum amount: 0.21 mg per cm ² ), 1 g of water, 1 g of Nafion (5 wt%), carbon (0.1 mg per cm ² ), 100 g of Iso proply alchol (IPA) Put in order to prepare solution 2. Solution 3 was prepared by adding 6 g of Nafion (5 wt%) and 100 g of IPA (Iso proply alchol) in order to beaker 3. The prepared GDL was spray-coated so that solution 1 was 0.21 mg / cm ² , and then the solution 2 was spray-coated to 0.09 mg / cm ^2, and then weighed to prepare an anode. Anode electrode containing Nafion 115 and Pt-ZSM-5 made above as a cathode using a commercial electrode containing 0.5 mg of platinum per cm ² was subjected to hot pressing at 135 ° C. and 800 Psig for 3 minutes. Electrode Assembly) was prepared. The fuel cell test station (Wona Tech smart II) is operated under conditions of 30cc / min oxygen, 100cc / min, 80 ℃, and 95% relative humidity by making the electrode including Pt-ZSM-5 made above become an anode. Performance was measured. In this embodiment, the Pt-ZSM-5 used in the above embodiment was used Pt-ZSM-5 of the above embodiments 1,2,3,4, respectively, and 6-a is a schematic diagram of the aforementioned alternate catalyst layer electrode. Figure 6-b is a diagram showing the cell performance of the MEA prepared by using the anode catalyst layer electrode as the anode shown in Figure 6-a.

Description of the IV curve will be described with the attachment of Table 2.

As shown in the table, in the case of the Pt-ZSM-5 catalysts prepared in Examples 1 to 4, the amount of platinum supported on ZSM-5 decreases from Cat 1 to Cat 4. Therefore, since the anode electrode was fixed at 0.3 mg / cm ² , the loading amount of Pt-ZSM-5 increased from Cat1 to Cat4. This means that the amount of platinum supported is the same but the amount of zeolite supported increases from Cat1 to Cat4. Therefore, it can be seen that the effect on the cell performance according to the amount of zeolite supported during electrode manufacturing. In FIG. 6B, the cell performance of the GCZC4 is greater than that of the GCZC1. In more detail, GCZC4, which has higher zeolite loading at higher current density than GCZC1, can be explained for three reasons. First, there is less platinum loss to GDL or membrane due to the high content of platinum in the zeolite pores. The second is that Cat4 has a smaller and more uniform particle size of platinum than Cat1, so that it is more uniformly dispersed on the outer surface of zeolite. Third, because GCZC4 has more zeolite loading, proton is zeolite. It is considered that the material transfer to move more smoothly in the pores is facilitated and the resistance by material transfer decreases.

Example 7:

This embodiment relates to the manufacture of a zeolite / carbon composite electrode (COMPCno: Composite Catalyst) prepared by mixing Pt-ZSM-5 and platinum / carbon. GDLs having an area of 3 cm x 3 cm were prepared and weighed. Commercial platinum / carbon 0.114g, Pt-ZSM-5 in a beaker 1 (amount of platinum: 0.21mg per cm ^2), carbon (cm ^2, the amount of 0.1 mg per), water 2g, 2g of Nafion, IPA (Iso proply alchol 100 g were added sequentially and mixed to prepare Solution 1. Solution 2 was prepared by adding Nagion 6g and IPA (Iso proply alchol) 100g in a beaker 2 in order. The prepared GDL was spray-coated so that Solution 1 was 0.3 mg / cm ² . After that, the solution 2 was spray-coated to 0.6 mg / cm ² to prepare a composite catalyst layer electrode, which was used as an anode. Membrane Electrode Assembly (MEA) was prepared by performing hot pressing at a temperature of 135 ° C. and 800 psig for 3 minutes with a commercial electrode coated with 0.5 mg of platinum per cm ² , Nafion 115, and the electrode made above. The composite membrane prepared above was used as a cathode, and the performance was measured using a fuel cell test station (Wona Tech smart II) under conditions of hydrogen 30cc / min, oxygen 100cc / min, 80 ° C and 95% relative humidity. . In this embodiment, Pt-ZSM-5 used in the above examples were used Pt-ZSM-5 of the above examples 1,2,3,4. 7-a is a schematic for the composite membrane prepared by the above-described method and 7-b is a cell performance result for the MEA prepared using the same.

In detail, in this case, as in the case of the GCZC of the alternate layer, the biggest cause of the improvement of the cell performance is the zeolite content contained in the anode and the particle size of platinum supported in and outside the zeolite pores. The thing originating in is mentioned. Not only is the zeolite content of COMPC4 the highest, but also the size of the platinum supported thereon is expected to be the smallest and most uniform, resulting in good dispersion. Therefore, the best cell performance when the anode is manufactured using COMPC4 is the reason that it shows the highest power density at high current density (this area mainly depends on material transfer resistance) due to the narrow zeolite content. The pore of the zeolite is thought to be the result of facilitating mass transfer, especially proton transfer. On the contrary, COMPC1 has the lowest zeolite content, and the zeolite content is considered to have a great influence on mass transfer. Therefore, in the case of the composite catalyst layer and the alternate catalyer, the effect of zeolite on the cell performance is considered to be very large and is the most important feature of the present invention. (A), (b) and (c) are cross-sectional photographs of the anode for the composite catalyst layer, (d) and (e) are cross-sectional photographs of the alternate catalyst layer, and (f) is commercial Pt / C. This is a cross section of the manufactured anode. In all photographs except commercial (f), zeolite is green, platinum is indigo blue, and Nafion is red. However, commercial (f) is green for carbon, platinum is blue, and Nafion is If it is red. When taking a cross-section picture, the material cut out by the knife and buried in the knife was noticeably different in the case of (a), (b) and (c) and (d) and (e), even though it was slightly buried throughout the electrode. Able to know. As shown in the figure, in the case of the composite layer (a, b, c), the zeolite is present relatively evenly throughout the electrode, while in the alternate layer (d, e), the zeolite layer is mainly present on the surface of the membrane. It can be seen that As already explained, the distribution of zeolite at the interface with the membrane reduces the loss of platinum to the membrane. This is because a significant portion of platinum is present in the zeolite pores. Electrochemical reactions (ie hydrogen oxidation) occur mainly at the interface between the membrane and the catalyst layer. This improves cell performance and is a feature of the present invention.

Example 8:

This example relates to a cathode electrode prepared by varying the weight ratio of platinum / carbon to platinum / zeolite as much as 7: 3 to as little as 4: 6, and the composition applied to the preparation of the cathode electrode is summarized in 8b.

To prepare a Cathode electrode, mix beaker 1 with commercially available platinum / carbon, Pt-ZSM-5, carbon (0.1 mg / cm ² ), 2 g of water, 2 g of Nafion, and 100 g of IPA (Iso proply alcohol). Solution 1 was prepared. 6 g of Nafion and 100 g of IPA (Iso proply alcohol) were sequentially added to the beaker 2 to prepare a solution 2. Prepared 3 x 3 cm and then ² for the GDL subjected to spray-coating a solution of 1 so that 0.3 mg per cm ² to conduct the spray-coating the solution 2 to 0.6 mg per cm ^2, the cathode of the total Pt loading is 0.2 mg / cm ² Prepared. In order to prepare Anode, commercially prepared platinum / carbon 0.109g, Nafion 2g, and IPA (Iso proply alchol) 100g were mixed in order to prepare Anode 3, and then Nabeion 6g and IPA (Iso proply) in beaker 4 alchol) 100g was added sequentially and mixed to prepare solution 4. Spray 3 g of solution 3 to 0.2 mg per cm ² on the prepared 3 x 3 cm ² GDL, and spray coating solution 4 to 0.6 mg per cm ² to give a total Pt loading of 0.2 mg / cm ² . Was prepared. Nafion 115, the two electrodes made above was subjected to hot pressing for 3 minutes at 135 ℃, 800Psig conditions to prepare a MEA (Membrane Electrode Assembly). Using the fuel cell test station (Wona Tech smart II) under the conditions of hydrogen 30cc / min oxygen 100cc / min, 80 ° C, and 100% relative humidity, the electrode containing Pt-ZSM-5 made above is an oxygen electrode. The performance was measured. In the present embodiment, Pt-ZSM-5 used in the above example was used as Pt-ZSM-5 of Example 5. 8-a is the result of the manufactured MEA. 8-a is the result of the manufactured MEA. 8-b is a table showing the weight of ZSM-5 in the catalyst.

Claims (1)

Pt (NH ₃ ) ₄ Cl ₂ 1wt% of platinum, 93wt% of water, 6wt% of ZSM-5 was added thereto, and stirred at 250 rpm for 24 hours at 60 ° C. After the stirring, the product was separated by filtration using a membrane filter. After filtering again with distilled water to prepare a platinum catalyst supported on the zeolite for fuel cells through the step of heating the powder dried at 80 ℃ for 12 hours at a nitrogen temperature atmosphere of 0.2 ℃ / min to 350 ℃,
Depositing a solution comprising platinum / carbon, a platinum catalyst supported on the zeolite and carbon onto a gas diffusion substrate,
The weight ratio of the platinum catalyst supported on the platinum / carbon and the zeolite is 5: 5, the method of producing a zeolite carbon composite electrode, characterized in that having a platinum size of 1 nm to 4 nm.

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