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CN118416910A - Alloy catalyst with high metal loading capacity and preparation method and application thereof - Google Patents

Alloy catalyst with high metal loading capacity and preparation method and application thereof Download PDF

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Publication number
CN118416910A
CN118416910A CN202410540945.6A CN202410540945A CN118416910A CN 118416910 A CN118416910 A CN 118416910A CN 202410540945 A CN202410540945 A CN 202410540945A CN 118416910 A CN118416910 A CN 118416910A
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catalyst
loading
noble metal
alloy
metal
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季相东
杨帆
李传亮
赵卿
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Shandong Guochuang Fuel Cell Technology Innovation Center Co ltd
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Shandong Guochuang Fuel Cell Technology Innovation Center Co ltd
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/89Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
    • B01J23/8913Cobalt and noble metals
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/89Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
    • B01J23/8926Copper and noble metals
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00Catalysts, in general, characterised by their form or physical properties
    • B01J35/30Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/391Physical properties of the active metal ingredient
    • B01J35/394Metal dispersion value, e.g. percentage or fraction
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00Catalysts, in general, characterised by their form or physical properties
    • B01J35/40Catalysts, in general, characterised by their form or physical properties characterised by dimensions, e.g. grain size
    • B01J35/45Nanoparticles
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02Impregnation, coating or precipitation
    • B01J37/0201Impregnation
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08Heat treatment
    • B01J37/082Decomposition and pyrolysis
    • B01J37/088Decomposition of a metal salt
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/16Reducing
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/34Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation
    • B01J37/341Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation
    • B01J37/343Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation of ultrasonic wave energy
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/86Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90Selection of catalytic material
    • H01M4/9041Metals or alloys
    • H01M4/905Metals or alloys specially used in fuel cell operating at high temperature, e.g. SOFC
    • H01M4/9058Metals or alloys specially used in fuel cell operating at high temperature, e.g. SOFC of noble metals or noble-metal based alloys

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Abstract

The invention provides an alloy catalyst with high metal loading, a preparation method and application thereof. The preparation method comprises the following steps: carrying out alloy material loading and alloying treatment on the first catalyst to obtain the alloy catalyst with high metal loading; wherein the first catalyst comprises a carbon support and a first noble metal supported on the carbon support; the alloy material includes a non-noble metal and a second noble metal. The preparation method provided by the invention improves the dispersibility of the nano particles in the high-metal-loading catalyst, reduces the size of the nano particles in the catalyst, can obviously improve the dispersibility of the nano particles in the high-loading catalyst on a carbon carrier, can greatly reduce the generation of large particles in the catalyst, and improves the catalytic activity and stability of the catalyst.

Description

Alloy catalyst with high metal loading capacity and preparation method and application thereof
Technical Field
The invention belongs to the technical field of catalysts, and relates to an alloy catalyst with high metal loading capacity, a preparation method and application thereof.
Background
Noble metals (such as platinum) are one of the irreplaceable catalysts in most chemical reactions, playing an important role in many fields such as fuel cells, petrochemical industry and the like, but the small reserves and the high price limit the large-scale application thereof. Taking the example of a cathode Oxygen Reduction Reaction (ORR) catalyst for a polymer electrolyte membrane fuel cell, the reaction is a complex process involving multiple electron generation and migration, and the kinetic reaction rate is slow. Noble metal platinum is the preferred active component of the current ORR catalysts, but still requires large amounts to ensure rapid reactions and long-term catalysis, and excessive battery cost limits its large-scale commercial application.
The alloy catalyst has better oxygen reduction reaction rate compared with the traditional Pt/C catalyst. Therefore, the method has important practical significance for reducing the Pt loading in the membrane electrode, for example, the science (DOI: 10.1126/science.1134569) reports that gold and platinum form an alloy with uniform loading, and the activity of the catalyst is successfully improved by utilizing the electronic state modulation of the platinum after alloying. Also, as in CN116251602a, a preparation method of a platinum-copper alloy catalyst, a platinum-copper alloy catalyst and application thereof are disclosed. At least comprises the following steps: (1) Mixing a raw material containing a platinum source, a copper source, a carrier and a surfactant with a solvent to obtain a mixed solution; (2) Mixing the mixed solution obtained in the step (1) with sodium borohydride, reacting, and roasting to obtain the platinum-copper alloy catalyst; the surfactant is one or more selected from polyvinylpyrrolidone, briji-76, briji-700, P-123, F-127, polyvinyl alcohol and polyethyleneimine.
However, since the transition element metal has a high reduction potential, it is difficult to reduce all of the transition element metal by a conventional liquid phase reduction method, and thus the preparation of the alloy catalyst is generally carried out by a vapor phase reduction method. However, when the metal loading in the catalyst is high, the catalyst is easy to cause agglomeration and growth of nano particles in the alloying process, so that the catalytic activity of the catalyst is affected.
Therefore, how to improve the dispersibility of the high-loading alloy catalyst and reduce the particle agglomeration of the high-loading alloy catalyst is a technical problem to be solved.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention aims to provide an alloy catalyst with high metal loading capacity, and a preparation method and application thereof. In the preparation process of the high-metal-loading alloy catalyst, the noble metal in the first catalyst is used as a nucleation site, the noble metal and the non-noble metal are loaded on the outer layer of the first catalyst, so that the dispersibility of the nano particles in the high-metal-loading alloy catalyst is improved, the size of the nano particles in the catalyst is reduced, the dispersibility of the nano particles in the high-loading alloy catalyst on a carbon carrier can be remarkably improved, the generation of large particles in the catalyst can be greatly reduced, and the catalytic activity and stability of the catalyst are improved.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for preparing an alloy catalyst with high metal loading, the method comprising the steps of:
Carrying out alloy material loading and alloying treatment on the first catalyst to obtain the alloy catalyst with high metal loading;
wherein the first catalyst comprises a carbon support and a first noble metal supported on the carbon support; the alloy material includes a non-noble metal and a second noble metal.
According to the preparation method provided by the invention, in the first catalyst, the first noble metal particle size is smaller and uniformly distributed on the carbon carrier, the first noble metal is used as a nucleation site, the alloy material is coated on the surface layer of the first noble metal nanoparticle, and after alloying treatment, the non-noble metal atoms on the outer layer of the nanoparticle migrate to the interior of the first noble metal nanoparticle, so that the first noble metal atoms and the non-noble metal atoms in the nanoparticle are orderly arranged to form an intermetallic compound, thereby improving the dispersibility of the nanoparticle in the high-metal-loading catalyst, reducing the size of the nanoparticle in the catalyst, remarkably improving the dispersibility of the nanoparticle in the high-loading catalyst on the carbon carrier, greatly reducing the generation of large particles in the catalyst, and improving the catalytic activity and stability of the catalyst.
In the case of pure non-noble metal material loading on the first catalyst, but in the case of non-alloy material loading (i.e. containing both the second noble metal and the non-noble metal) on the first catalyst, although the alloy catalyst is finally obtained, the nanoparticles in the catalyst are severely agglomerated due to the oswald effect of the high loading of noble metal in the first catalyst during the high temperature alloying process.
Preferably, the first noble metal and the second noble metal are the same kind.
Preferably, the first noble metal element and the second noble metal element each independently include any one or a combination of at least two of Pt, pd, ru, or Rh.
Preferably, the non-noble metal element comprises any one or a combination of at least two of iron, cobalt, nickel, copper, manganese or chromium.
In the present invention, noble metal elements and non-noble metal elements other than those provided above can be used as alloy catalysts, and the present invention is applicable to the same types of elements that can be used for oxygen catalytic reduction.
Preferably, in the alloy catalyst with high metal loading, the loading of the first noble metal is 20 to 30%, for example, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%, etc., but not limited to the recited values, and other non-recited values within the range of values are equally applicable.
In the invention, the loading amount of the first noble metal in the alloy catalyst is too low and is lower than 20%, and under the same high loading amount, the loading amount of the alloy material in the alloy catalyst is too high, so that the nano particles of the first noble metal are fewer and cannot provide enough nucleation particles, and the alloy material is self-nucleated; the loading of the first noble metal in the alloy catalyst is too high and higher than 30%, and under the same high loading condition, the loading of the alloy material in the alloy catalyst is too low, and the alloying degree of the alloy material in the first noble metal is seriously influenced. Complete ordering between atoms of the alloy catalyst cannot be achieved.
Preferably, the preparation method of the first catalyst comprises a solvent reduction method and/or an impregnation reduction method.
It should be noted that the first catalyst provided by the invention can be prepared by itself, and the preparation method and the preparation parameters are both conventional technical means, and the corresponding commercially available catalyst types (such as commercially available Pt/C catalysts) with composite requirements can also be directly purchased, so long as the corresponding technical characteristics of the first catalyst are compounded.
Preferably, the particle size of the first noble metal nanoparticles in the first catalyst is 2 to 3nm, for example, 2nm, 2.1nm, 2.2nm, 2.3nm, 2.4nm, 2.5nm, 2.6nm, 2.7nm, 2.8nmm, 2.9nm or 3nm, etc., but not limited to the recited values, and other non-recited values within the range of values are equally applicable.
In the first catalyst provided by the invention, if the particle size range of the first noble metal nanoparticles is too large, the particle size of the alloy catalyst is affected.
Preferably, in the high metal loading alloy catalyst, the loading of the alloy material is 20 to 30%, for example 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%, etc., but not limited to the recited values, and other non-recited values within the range of values are equally applicable.
In the invention, the loading amount of the alloy material in the alloy catalyst is too low and is lower than 20%, and under the same high loading amount, the loading amount of the first noble metal in the alloy catalyst is too high, so that the first catalyst is unevenly distributed, and the agglomeration of the alloy catalyst nano particles is caused; the loading of the alloy material in the alloy catalyst is too high and higher than 30%, and under the same high loading condition, the loading of the first noble metal in the alloy catalyst is too low, so that the nucleation sites of the nano particles in the first catalyst are reduced, and the subsequent alloying reaction is influenced. .
Preferably, the loading method of the alloy material includes a solvent reduction method and/or a dip reduction method.
Preferably, the loading method of the alloy material comprises the following steps:
the first catalyst is mixed and immersed in a mixed solution of a second noble metal salt solution and a non-noble metal salt solution, dried, reduced and sintered, and then alloyed.
Preferably, the method of mixed impregnation comprises ultrasonic dispersion.
Preferably, the method of drying comprises freeze drying.
Preferably, the sintering atmosphere of the reduction sintering includes a reducing atmosphere.
Preferably, the reducing atmosphere comprises a mixed atmosphere of hydrogen and a protective gas.
Preferably, the temperature rise rate of the reduction sintering is 3 to 5 ℃ per minute, for example, 3 ℃ per minute, 4 ℃ per minute, 5 ℃ per minute, or the like, but is not limited to the recited values, and other non-recited values within the range of the recited values are equally applicable.
The reduction sintering temperature is preferably 200 to 300 ℃, for example 200 ℃, 210 ℃, 220 ℃, 230 ℃, 240 ℃, 250 ℃, 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, or the like, but is not limited to the recited values, and other values not recited in the range of values are equally applicable.
The temperature of the alloying treatment is preferably 600 to 800 ℃, for example 600 ℃, 610 ℃, 620 ℃, 630 ℃, 640 ℃, 650 ℃, 660 ℃, 670 ℃, 680 ℃, 690 ℃, 700 ℃, 710 ℃, 720 ℃, 730 ℃, 740 ℃, 750 ℃, 760 ℃, 770 ℃, 780 ℃, 790 ℃, 800 ℃, or the like, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.
It should be noted that, the alloying treatment process (i.e. after loading the alloy material, an alloying reaction needs to take place to finally obtain the alloy material) provided by the invention can be implemented by high-temperature heat treatment, or can be implemented by other technical schemes known to those skilled in the art in a reasonable range.
As a preferred technical scheme, the preparation method comprises the following steps:
The first catalyst with the grain size of 2-3 nm is mixed and immersed in the mixed solution of the second noble metal salt solution and the non-noble metal salt solution by an ultrasonic dispersion method, freeze-dried, heated to 200-300 ℃ at the heating rate of 3-5 ℃/min under the reducing atmosphere for reduction sintering, and then subjected to alloying treatment at 600-800 ℃;
Wherein the first catalyst comprises a carbon support and a first noble metal supported on the carbon support; the alloy material comprises non-noble metal and second noble metal, wherein the molar ratio of the second noble metal to the non-noble metal is (1-10): 1; the first noble metal and the second noble metal are the same in kind; in the alloy catalyst with high metal loading, the loading of the first noble metal is 20-30%, and the loading of the alloy material is 20-30%.
In a second aspect, the present invention provides a method for preparing a high metal loading alloy catalyst prepared by the preparation method according to the first aspect.
Preferably, the alloy catalyst with high metal loading has a total metal loading of 40-50%, such as 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49% or 50%, etc., but is not limited to the recited values, and other non-recited values within the range are equally applicable.
The alloy catalyst provided by the invention has high metal load, and the active component nano particles in the alloy catalyst have good dispersibility, no obvious agglomeration phenomenon and high oxygen reduction catalytic activity.
Preferably, in the alloy catalyst with high metal loading, the molar ratio of the sum of the first noble metal and the second noble metal to the non-noble metal is (1-10): 1, such as 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, etc., but not limited to the recited values, and other non-recited values within the range of values are equally applicable.
In a third aspect, the present invention also provides the use of a high metal loading alloy catalyst comprising using a high metal loading alloy catalyst as described in the second aspect for an oxygen reduction catalytic reaction.
Compared with the prior art, the invention has the following beneficial effects:
According to the preparation method provided by the invention, in the first catalyst, the first noble metal particle size is smaller and uniformly distributed on the carbon carrier, the first noble metal is used as a nucleation site, the alloy material is coated on the surface layer of the first noble metal nanoparticle, and after alloying treatment, the non-noble metal atoms on the outer layer of the nanoparticle migrate to the interior of the first noble metal nanoparticle, so that the first noble metal atoms and the non-noble metal atoms in the nanoparticle are orderly arranged to form an intermetallic compound, thereby improving the dispersibility of the nanoparticle in the high-metal-loading catalyst, reducing the size of the nanoparticle in the catalyst, remarkably improving the dispersibility of the nanoparticle in the high-loading catalyst on the carbon carrier, greatly reducing the generation of large particles in the catalyst, and improving the catalytic activity and stability of the catalyst.
Drawings
Fig. 1 is a TEM image of the alloy catalyst provided in example 1.
Fig. 2 is a TEM image of the alloy catalyst provided in comparative example 1.
Detailed Description
The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.
Example 1
The present example provides a high metal loading alloy catalyst (Pt-Co alloy, pt and Co molar ratio of 3:1, total loading of 50%, carrier carbon carrier).
The preparation method of the alloy catalyst comprises the following steps:
mixing a purchased Zhuang Xinmo Feng Pt/C first catalyst (the loading amount of Pt is 30 percent, the grain size of Pt nano particles is 2-3 nm), chloroplatinic acid (40 g/ml) aqueous solution and cobalt chloride hexahydrate, performing ultrasonic dispersion for 30 minutes, ensuring that a metal precursor (namely an alloy material precursor) and the Pt/C first catalyst are uniformly dispersed, obtaining an impregnating solution, and freeze-drying the mixed impregnating solution to sublimate water in the impregnating solution;
Grinding the freeze-dried mixture into powder, placing the powder into a magnetic boat, and heating to 250 ℃ under the condition of hydrogen-argon mixture (the volume fraction of hydrogen is 5%) at a heating rate of 5 ℃/min for calcination and reduction at a high temperature, wherein the reduction time is 2 hours per gram of sample;
And (3) continuously heating the reduced sample (wherein the loading amount of the platinum-cobalt alloy material obtained by dipping reduction is 20%) to 700 ℃ for high-temperature alloying for 1h, naturally cooling to room temperature, and taking out to obtain the alloy catalyst in the platinum-cobalt alloy loading and carbon carrier.
Example 2
The present example provides a high metal loading alloy catalyst (Pt-Co alloy, pt and Co molar ratio of 3:1, total loading of 50%, carrier carbon carrier).
The preparation method of the alloy catalyst comprises the following steps:
Preparing a Pt/C first catalyst by a sol-gel method (the loading of Pt is 25 percent, and the particle size of Pt nano particles is 2-3 nm),
Firstly, dissolving 0.675g of chloroplatinic acid 0.75g of a carbon carrier in 250ml of ethylene glycol, carrying out ultrasonic dispersion for 1 hour, namely, uniformly dispersing a metal precursor in a solvent, adding a 2mol/L sodium hydroxide aqueous solution to ensure that the pH value of a solution system reaches 9-11, stirring again for 30 minutes to uniformly disperse, placing the system in an oil bath pot, reacting for 2 hours at 130-150 ℃, stably reducing the system to room temperature, regulating the pH value of the system to 1-3 by using a 1mol/L dilute hydrochloric acid solution, washing, filtering to remove impurity ions on the surface of the catalyst, and drying in a vacuum oven at 60 ℃ for 12 hours to obtain a Pt/C catalyst with a platinum load of 25%;
Mixing the catalyst, chloroplatinic acid (40 g/ml) aqueous solution and cobalt chloride hexahydrate (the molar ratio of platinum in chloroplatinic acid to cobalt chloride hexahydrate is 3:1), performing ultrasonic dispersion for 30 minutes, ensuring that a metal precursor (namely an alloy material precursor) and a Pt/C first catalyst are uniformly dispersed to obtain an impregnating solution, and freeze-drying the mixed impregnating solution to sublimate water in the impregnating solution;
Grinding the freeze-dried mixture into powder, placing the powder into a magnetic boat, and heating to 300 ℃ at a heating rate of 3 ℃/min under the condition of hydrogen-argon mixed gas (the volume fraction of hydrogen is 10 percent) for calcination and reduction at a high temperature, wherein the reduction time is 3 hours per gram of sample;
And (3) continuously heating the reduced sample (wherein the loading amount of the platinum-cobalt alloy material obtained by dipping reduction is 25%) to 700 ℃ for high-temperature alloying for 1h, naturally cooling to room temperature, and taking out to obtain the alloy catalyst in the platinum-cobalt alloy loading and carbon carrier.
Example 3
The present example provides a high metal loading alloy catalyst (Pt-Co alloy, pt and Co molar ratio of 3:1, total loading of 50%, carrier carbon carrier).
The preparation method of the alloy catalyst comprises the following steps:
Mixing a purchased Zhuang Xinmo-rich Pt/C first catalyst (the loading amount of Pt is 20 percent, the grain size of Pt nano particles is 2-3 nm), chloroplatinic acid (40 g/ml) aqueous solution and cobalt chloride hexahydrate (the mole ratio of platinum in chloroplatinic acid to cobalt chloride hexahydrate is 3:1), performing ultrasonic dispersion for 30 minutes, ensuring that a metal precursor (namely an alloy material precursor) and the Pt/C first catalyst are uniformly dispersed, obtaining an impregnating solution, and freeze-drying the mixed impregnating solution to sublimate water in the impregnating solution;
Grinding the freeze-dried mixture into powder, placing the powder into a magnetic boat, and heating to 200 ℃ at a heating rate of 4 ℃/min under the condition of hydrogen-argon mixed gas (the volume fraction of hydrogen is 5%), and calcining and reducing at a high temperature for 2 hours per gram of sample;
and (3) continuously heating the reduced sample (wherein the loading amount of the platinum-cobalt alloy material obtained by dipping reduction is 30%) to 800 ℃ for high-temperature alloying for 1h, naturally cooling to room temperature, and taking out to obtain the alloy catalyst in the platinum-cobalt alloy loading and carbon carrier.
Example 4
The present example provides a high metal loading alloy catalyst (Pt-Cu alloy, total loading 40%, molar ratio of Pt to Cu 10:1, carrier carbon carrier).
The preparation method of the alloy catalyst comprises the following steps:
Mixing a purchased Zhuang Xinmo-rich Pt/C first catalyst (the loading amount of Pt is 20 percent, the grain size of Pt nano particles is 2-3 nm), chloroplatinic acid (40 g/ml) aqueous solution and copper nitrate (the mol ratio of platinum in chloroplatinic acid to copper hexanitrate is 10:1), performing ultrasonic dispersion for 30 minutes, ensuring that a metal precursor (namely an alloy material precursor) and the Pt/C first catalyst are uniformly dispersed, obtaining an impregnating solution, and freeze-drying the mixed impregnating solution to sublimate water in the impregnating solution;
Grinding the freeze-dried mixture into powder, placing the powder into a magnetic boat, and heating to 250 ℃ under the condition of hydrogen-argon mixture (the volume fraction of hydrogen is 5%) at a heating rate of 5 ℃/min for calcination and reduction at a high temperature, wherein the reduction time is 2 hours per gram of sample;
And (3) continuously heating the reduced sample (wherein the loading amount of the platinum-copper alloy material obtained by dipping reduction is 20%) to 700 ℃ for high-temperature alloying for 1h, naturally cooling to room temperature, and taking out to obtain the alloy catalyst in the platinum-copper alloy loading and carbon carrier.
Example 5
The difference between this example and example 1 is that the loading of Pt in the first catalyst in this example was 10%, and the loading of the platinum-cobalt alloy material obtained by dip reduction was 40% in the corresponding reduced sample.
The remaining preparation methods and parameters were consistent with example 1.
Example 6
The difference between this example and example 1 is that the loading of Pt in the first catalyst in this example was 40%, and the loading of the platinum-cobalt alloy material obtained by dip reduction was 10% in the corresponding reduced sample.
The remaining preparation methods and parameters were consistent with example 1.
Example 7
The difference between this example and example 1 is that the particle size of the platinum nanoparticles of the first catalyst provided in this example is 4 to 10nm.
The remaining preparation methods and parameters were consistent with example 1.
Comparative example 1
The present comparative example provides a high metal loading alloy catalyst (Pt-Co alloy, pt and Co molar ratio of 3:1, total loading of 50%, support carbon support).
The preparation method of the alloy catalyst comprises the following steps:
30ml of an aqueous solution of chloroplatinic acid (40 g/ml), 187 cobalt chloride hexahydrate, 0.5g carbon support were placed in a small beaker, the mass of the precursor added being varied so that Pt: co=3:1 in the catalyst;
ultrasonic dispersion is carried out for 30 minutes, so that the metal precursor and the carbon carrier are ensured to be uniformly dispersed, and the mixed impregnating solution is freeze-dried, so that the water in the impregnating solution is sublimated;
Grinding the freeze-dried mixture into powder, placing the powder into a magnetic boat, and heating to 250 ℃ under the condition of hydrogen-argon mixture (the volume fraction of hydrogen is 5%) at a heating rate of 5 ℃/min for calcination and reduction at a high temperature, wherein the reduction time is 2 hours per gram of sample;
And (3) continuously heating the reduced sample (wherein the loading amount of the platinum-cobalt alloy material obtained by dipping reduction is 20%) to 700 ℃ for high-temperature alloying for 1h, naturally cooling to room temperature, and taking out to obtain the alloy catalyst in the platinum-cobalt alloy loading and carbon carrier.
Comparative example 2
The present comparative example provides a high metal loading alloy catalyst (Pt-Co alloy, pt and Co molar ratio of 3:1, total loading of 50%, support carbon support).
The preparation method of the alloy catalyst comprises the following steps:
(1) Preparing a Pt/C first catalyst, wherein the mass fraction of Pt in the catalyst is 45%;
(2) Mixing the Pt/C first catalyst and cobalt chloride hexahydrate (ensuring that the molar ratio of Pt to Co is 3:1), performing ultrasonic dispersion for 30 minutes, ensuring that a metal precursor (namely a cobalt precursor) and the Pt/C first catalyst are uniformly dispersed to obtain an impregnating solution, and freeze-drying the mixed impregnating solution to sublimate water in the impregnating solution;
Grinding the freeze-dried mixture into powder, placing the powder into a magnetic boat, and heating to 250 ℃ under the condition of hydrogen-argon mixture (the volume fraction of hydrogen is 5%) at a heating rate of 5 ℃/min for calcination and reduction at a high temperature, wherein the reduction time is 2 hours per gram of sample;
and (3) continuously heating the reduced sample to 700 ℃ for high-temperature alloying for 1h, naturally cooling to room temperature, and taking out to obtain the alloy catalyst in the platinum-cobalt alloy load and carbon carrier.
Fig. 1 shows a TEM image of the alloy catalyst provided in example 1.
Fig. 2 shows a TEM image of the alloy catalyst provided in comparative example 1.
As can be seen from FIGS. 1 to 2, the catalyst obtained by the preparation method provided in comparative example 1 had a remarkable large particle phenomenon and a non-uniform particle size distribution.
The alloy catalysts provided in examples 1-7 and comparative examples 1-2 were subjected to particle size testing of the active component, the microscopic morphology of the catalyst was photographed, and 200 nanoparticles were randomly selected for statistics to obtain the average particle size of the catalyst nanoparticles, and the test results are shown in table 1.
TABLE 1
The alloy catalysts provided in examples 1 to 7 and comparative examples 1 to 2 were subjected to oxygen reduction catalytic performance test, LSV curves were measured in 0.1M perchloric acid solution using a three-electrode system, and mass activity of catalytic oxygen reduction reaction was calculated by K-L equation, and the test results are shown in Table 2.
TABLE 2
Catalytic performance for oxygen reduction (A/mg)
Example 1 0.22
Example 2 0.23
Example 3 0.21
Example 4 0.21
Example 5 0.13
Example 6 0.15
Example 7 0.11
Comparative example 1 0.10
Comparative example 2 0.14
As can be seen in combination with fig. 1-2 and tables 1-2: the alloy catalyst prepared by adopting the step reduction has higher catalytic oxygen reduction efficiency, the mass activity is higher than 0.2A/mg,
According to the preparation method provided by the invention, the alloy catalyst with high metal loading is obtained by carrying out the loading of metal atoms in the catalyst step by step, so that the dispersibility of nano particles in the high-loading catalyst on a carbon carrier can be remarkably improved, meanwhile, the generation of large particles in the catalyst can be greatly reduced, and the catalytic activity and stability of the catalyst are improved.
From the data of examples 1 and 5 and 6, it is known that the loading of the first noble metal in the first catalyst is too low, less than 20%, and the loading of the alloy material in the alloy catalyst is too high, thereby being unfavorable for the nucleation and growth of the alloy catalyst to cause the growth of nano particles; the loading of the first noble metal in the alloy catalyst is too high and higher than 30%, and under the same high loading condition, the loading of the alloy material in the alloy catalyst is too low, so that the alloying degree is reduced, and the catalytic performance of the catalyst is affected.
From the data of examples 1 and 7, it is apparent that the too large particle size of the first noble metal nanoparticles in the first catalyst can seriously affect the distribution of the alloy catalyst nanoparticles on the carrier and the growth of the particles, so that the catalytic active sites on the surface of the catalyst are reduced and the catalytic performance is lowered.
From the data of example 1 and comparative example 1, it is known that when the alloy catalyst of noble metal and non-noble metal is prepared in one step (i.e., noble metal is added at one time), the metal loading in the catalyst is greater than 40%, and the precursor content in the catalyst is high, the nanoparticles in the catalyst are large particles due to oswald ripening during the high temperature reduction and calcination processes, so that the problems of dispersion and growth of the nanoparticles cannot be solved.
As is apparent from the data of example 1 and comparative example 2, when preparing the alloy catalyst, only the loading of the non-noble metal (i.e., the total loading of the noble metal in the alloy catalyst included in the first catalyst) was performed on the basis of the first catalyst, and although the alloy catalyst was similarly obtained, the transition element metal was distributed on the surface of the platinum nanoparticles, resulting in a lower degree of alloying, a reduced intermetallic phase interaction force, and an influence on the catalytic activity of the catalyst.
In summary, in the preparation method provided by the invention, in the first catalyst, the first noble metal particle size is smaller and uniformly distributed on the carbon carrier, the first noble metal is taken as a nucleation site, the alloy material is coated on the surface layer of the first noble metal nanoparticle, and after alloying treatment, the non-noble metal atoms on the outer layer of the nanoparticle migrate to the interior of the first noble metal nanoparticle, so that the first noble metal atoms and the non-noble metal atoms in the nanoparticle are orderly arranged to form an intermetallic compound, thereby improving the dispersibility of the nanoparticle in the high-metal-loading catalyst, reducing the size of the nanoparticle in the catalyst, remarkably improving the dispersibility of the nanoparticle in the high-loading catalyst on the carbon carrier, greatly reducing the generation of large particles in the catalyst, and improving the catalytic activity and stability of the catalyst.
The applicant declares that the above is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be apparent to those skilled in the art that any changes or substitutions that are easily conceivable within the technical scope of the present invention disclosed by the present invention fall within the scope of the present invention and the disclosure.

Claims (10)

1. A method for preparing an alloy catalyst with high metal loading, which is characterized by comprising the following steps:
Carrying out alloy material loading and alloying treatment on the first catalyst to obtain the alloy catalyst with high metal loading;
wherein the first catalyst comprises a carbon support and a first noble metal supported on the carbon support; the alloy material includes a non-noble metal and a second noble metal.
2. The method for producing a high metal-loading alloy catalyst according to claim 1, wherein the first noble metal and the second noble metal are the same in kind;
Preferably, the first noble metal element and the second noble metal element each independently include any one or a combination of at least two of Pt, pd, ru, or Rh;
preferably, the non-noble metal element comprises any one or a combination of at least two of iron, cobalt, nickel, copper, manganese or chromium;
Preferably, in the alloy catalyst with high metal loading, the loading of the first noble metal is 20-30%;
Preferably, the preparation method of the first catalyst comprises a solvent reduction method and/or an impregnation reduction method;
Preferably, the particle size of the first noble metal nanoparticles in the first catalyst is 2 to 3nm.
3. The method for preparing the high metal loading alloy catalyst according to claim 1 or 2, wherein the loading amount of the alloy material in the high metal loading alloy catalyst is 20-30%;
preferably, the loading method of the alloy material includes a solvent reduction method and/or a dip reduction method.
4. The method for preparing a high metal loading alloy catalyst according to claim 3, wherein the loading method of the alloy material comprises:
the first catalyst is mixed and immersed in a mixed solution of a second noble metal salt solution and a non-noble metal salt solution, dried, reduced and sintered, and then alloyed.
5. The method for preparing a high metal loading alloy catalyst according to claim 4, wherein the method for mixed impregnation comprises ultrasonic dispersion;
preferably, the method of drying comprises freeze drying;
Preferably, the sintering atmosphere of the reduction sintering comprises a reducing atmosphere;
preferably, the reducing atmosphere comprises a mixed atmosphere of hydrogen and a protective gas;
preferably, the heating rate of the reduction sintering is 3-5 ℃/min;
preferably, the temperature of the reduction sintering is 200-300 ℃.
6. The method for producing a high metal loading alloy catalyst according to any one of claims 1 to 5, wherein the temperature of the alloying treatment is 600 to 800 ℃.
7. The method for preparing an alloy catalyst with high metal loading according to any one of claims 1 to 6, wherein the preparation method comprises the steps of:
The first catalyst with the grain size of 2-3 nm is mixed and immersed in the mixed solution of the second noble metal salt solution and the non-noble metal salt solution by an ultrasonic dispersion method, freeze-dried, heated to 200-300 ℃ at the heating rate of 3-5 ℃/min under the reducing atmosphere for reduction sintering, and then subjected to alloying treatment at 600-800 ℃;
The first catalyst comprises a carbon carrier and first noble metal loaded on the carbon carrier, and the particle size of first noble metal nano particles in the first catalyst is 2-3 nm; the alloy material comprises non-noble metal and second noble metal, wherein the molar ratio of the second noble metal to the non-noble metal is (1-10): 1; the first noble metal and the second noble metal are the same in kind; in the alloy catalyst with high metal loading, the loading of the first noble metal is 20-30%, and the loading of the alloy material is 20-30%.
8. A method for preparing a high metal loading alloy catalyst, wherein the high metal loading alloy catalyst is prepared by the preparation method according to any one of claims 1 to 7.
9. The method for preparing a high metal loading alloy catalyst according to claim 8, wherein the total metal loading of the high metal loading alloy catalyst is 40-50%;
Preferably, in the alloy catalyst with high metal loading, the molar ratio of the sum of the first noble metal and the second noble metal to the non-noble metal is (1 to 10): 1.
10. Use of the high metal loading alloy catalyst according to claim 8 or 9 for oxygen reduction catalytic reactions.
CN202410540945.6A 2024-04-30 2024-04-30 Alloy catalyst with high metal loading capacity and preparation method and application thereof Pending CN118416910A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118892848A (en) * 2024-09-30 2024-11-05 浙江大学 A bimetallic nano alloy catalyst and its preparation method and application
CN119920911A (en) * 2025-04-03 2025-05-02 中国科学院赣江创新研究院 An oxygen reduction electrocatalyst and its preparation method and application

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118892848A (en) * 2024-09-30 2024-11-05 浙江大学 A bimetallic nano alloy catalyst and its preparation method and application
CN119920911A (en) * 2025-04-03 2025-05-02 中国科学院赣江创新研究院 An oxygen reduction electrocatalyst and its preparation method and application

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