阅读说明：本技术 一种碳负载金属纳米团簇催化剂的制备方法 (Preparation method of carbon-supported metal nanocluster catalyst ) 是由 张显 吴守良 刘俊 张海民 梁长浩 王新磊 于 2020-03-03 设计创作，主要内容包括：本发明公开了一种碳负载金属纳米团簇催化剂的制备方法,涉及金属团簇催化剂制备领域,包括以下制备步骤：1)将碳载体浸泡至酸处理液中,随后过滤洗涤,制备得到富官能团碳载体粉末；2)将富官能团碳载体粉末浸泡至可溶性金属盐溶液中,吸附后洗涤、冷冻干燥,制备得到金属吸附碳载体材料；3)将金属吸附碳载体材料置于挥发的硫醇蒸气中进行熏蒸处理,制备得到硫醇-金属-碳载体复合材料；4)将硫醇-金属-碳载体复合材料在保护气氛下进行煅烧,制备得到碳负载金属纳米团簇催化剂；本发明将金属离子吸附于酸处理后的碳材料上,随后采用硫醇熏蒸的方法,制备得到表面有硫固定的金属纳米团簇催化剂,催化剂的金属纳米团簇尺寸小,分散度好。(The invention discloses a preparation method of a carbon-loaded metal nanocluster catalyst, which relates to the field of preparation of metal nanocluster catalysts and comprises the following preparation steps: 1) soaking the carbon carrier into an acid treatment solution, and then filtering and washing to prepare carbon carrier powder rich in functional groups; 2) soaking the carbon carrier powder rich in functional groups into a soluble metal salt solution, and carrying out washing and freeze drying after adsorption to prepare a metal adsorption carbon carrier material; 3) putting the metal-adsorbed carbon carrier material into volatile mercaptan vapor for fumigation treatment to prepare a mercaptan-metal-carbon carrier composite material; 4) calcining the mercaptan-metal-carbon carrier composite material in a protective atmosphere to prepare the carbon-supported metal nanocluster catalyst; according to the invention, metal ions are adsorbed on the carbon material after acid treatment, and then the metal nanocluster catalyst with the sulfur fixed on the surface is prepared by adopting a mercaptan fumigation method, wherein the metal nanoclusters of the catalyst are small in size and good in dispersity.)

1. A preparation method of a carbon-supported metal nanocluster catalyst is characterized by comprising the following preparation steps:

1) soaking the carbon carrier into an acid treatment solution, and then filtering and washing to prepare carbon carrier powder rich in functional groups;

2) soaking the carbon carrier powder rich in functional groups into a soluble metal salt solution, and carrying out washing and freeze drying after adsorption to prepare a metal adsorption carbon carrier material;

3) putting the metal-adsorbed carbon carrier material into volatile mercaptan vapor for fumigation treatment to prepare a mercaptan-metal-carbon carrier composite material;

4) and calcining the mercaptan-metal-carbon carrier composite material under a protective atmosphere to prepare the carbon-supported metal nanocluster catalyst.

2. The method of claim 1, wherein the carbon support of step 1) comprises one or more of activated carbon, conductive carbon black, carbon paper, carbon cloth, and grapheme carbon material.

3. The method for preparing a carbon-supported metal nanocluster catalyst as recited in claim 1, wherein said acid treatment liquid of step 1) includes a piranha solution; the mass ratio of the carbon carrier powder to the acid treatment solution is 0.5-3.5: 100; the soaking time is 10-48 h; in the filtration washing, the filtrate is washed with deionized water until the pH of the final filtrate is between 6 and 7.

4. The method for preparing a carbon-supported metal nanocluster catalyst as recited in claim 1, wherein said soluble metal salt solution of step 2) comprises one or more mixed solution of Pt salt, Au salt, Ru salt, Rh salt, Fe salt, Co salt, Ni salt, Pd salt, Ag salt, and said soluble metal salt solution is 0.005-5 mol/L.

5. The method for preparing a carbon-supported metal nanocluster catalyst as recited in claim 1, wherein said step 2) is performed by mixing said functional group-rich carbon support powder with a soluble metal salt solution in a ratio of 0.1-3.5: 100; the soaking is carried out at 25-99 deg.C for 5-20 h.

6. The method for preparing a carbon-supported metal nanocluster catalyst according to claim 1, wherein the fumigating treatment in step 3) is carried out in a closed vacuum environment or an inert gas environment at 10-220 ℃ for 5-100 h.

7. The method for preparing a carbon-supported metal nanocluster catalyst as recited in claim 1, wherein said thiol of said step 3) comprises one or more of methyl mercaptan, ethyl mercaptan, octyl mercaptan, cyclohexyl mercaptan, cyclopentyl mercaptan, n-dodecyl mercaptan, 2-propyl mercaptan, heptyl mercaptan, phenethyl mercaptan, and butyl mercaptan.

8. The method for preparing a carbon-supported metal nanocluster catalyst as recited in claim 1, wherein the calcination in step 4) is performed by heating to 300-700 ℃ at a heating rate of 5-10 ℃/min, and maintaining the temperature for 1-4 h.

Technical Field

The invention relates to the field of preparation of metal cluster catalysts, in particular to a preparation method of a carbon-supported metal nanocluster catalyst.

Background

The metal cluster catalyst shows excellent catalytic performance of the nano catalytic material by virtue of unique surface effect, volume effect and quantum size effect, is widely applied to low-temperature catalysis of carbon monoxide (CO) oxidation, fuel cell reaction, low-temperature water-gas shift reaction, nitrogen oxide (NOx) catalytic decomposition and the like in the chemical field, and is called as a fourth-generation catalyst. The size and appearance, atomic composition, surface environment and carrier of the metal cluster catalyst all have important influence on the catalytic performance of the catalyst.

At present, most of metal nano-catalysts are synthesized by a solution phase, and in order to prevent agglomeration in the application process, the metal nano-catalysts are also required to be loaded on a carrier. However, a large amount of surfactant exists on the surface of the metal nanocluster catalyst synthesized in the solution phase, which seriously hinders the improvement of the catalytic performance of the metal nanocluster catalyst, and the direct removal of the surfactant on the cluster surface can cause the agglomeration of the metal nanocluster catalyst, which reduces the catalytic performance of the metal nanocluster catalyst.

For example, a chinese patent document discloses a method for preparing a metal cluster photostable catalyst and its application, and publication No. CN109499567A discloses a method for preparing a metal cluster photostable catalyst and a method for improving the photostability of a metal cluster by a combination strategy of surface property control and/or interface modification, but the catalyst is synthesized in a solution phase, and a large amount of surfactant exists on the surface, which seriously hinders the improvement of the catalytic performance.

Disclosure of Invention

The invention provides a preparation method of a carbon-supported metal nanocluster catalyst, aiming at overcoming the problems that a large amount of surfactant exists on the surface of the metal nanocluster catalyst synthesized by the existing solution phase, and the improvement of the catalytic performance of the metal nanocluster catalyst is seriously hindered, but the surfactant on the surface of the cluster is directly removed, so that the metal nanocluster catalyst is agglomerated, the catalytic performance of the metal nanocluster catalyst is reduced, and the like.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a carbon-supported metal nanocluster catalyst comprises the following preparation steps:

1) soaking the carbon carrier into an acid treatment solution, and then filtering and washing to prepare carbon carrier powder rich in functional groups;

2) soaking the carbon carrier powder rich in functional groups into a soluble metal salt solution, and carrying out washing and freeze drying after adsorption to prepare a metal adsorption carbon carrier material;

3) putting the metal-adsorbed carbon carrier material into volatile mercaptan vapor for fumigation treatment to prepare a mercaptan-metal-carbon carrier composite material;

4) and calcining the mercaptan-metal-carbon carrier composite material under a protective atmosphere to prepare the carbon-supported metal nanocluster catalyst.

The invention firstly soaks the carbon carrier into acid treatment liquid to carry out acid treatment, the prepared carbon carrier powder with rich functional groups is rich in adsorption group hydroxyl and carboxyl on the surface, the carbon carrier powder with rich functional groups adsorbs metal ions by utilizing the surface adsorption group after being soaked into soluble metal salt solution, then the metal adsorption carbon carrier material is placed into volatile mercaptan vapor to carry out fumigation treatment, at the moment, mercaptan molecules slowly volatilize and diffuse, and slowly form metal mercaptan coordination compounds with the metal adsorbed by the metal adsorption carbon carrier material to prevent the agglomeration of metal clusters to prepare the mercaptan-metal-carbon carrier composite material, finally high-temperature calcination is carried out under protective atmosphere to reduce the metal mercaptan coordination compounds in situ, at the moment, the mercaptan molecules can prevent the agglomeration of the metal clusters in the high-temperature reduction, and simultaneously, the high-temperature calcination carries out alkyl carbonization on the mercaptan molecules, therefore, the carbon-supported metal nanocluster catalyst with sulfur fixed on the surface is obtained, and at the moment, the sulfur atoms bonded on the surface of the metal nanocluster can also form protection for metal agglomeration, so that the catalyst is prevented from being oxidized in the storage and use processes, and the stability of the performance of the catalyst is improved.

Preferably, the carbon support in step 1) comprises one or more of activated carbon, conductive carbon black, carbon paper, carbon cloth and graphene.

The carbon carrier is a graphitized carbon material.

Preferably, the acid treatment solution of step 1) comprises a piranha solution; the mass ratio of the carbon carrier to the acid treatment solution is 0.5-3.5: 100; the soaking time is 10-48 h; in the filtration washing, the filtrate is washed with deionized water until the pH of the final filtrate is between 6 and 7.

At this ratio, the carbon carrier is acid-treated more effectively.

Preferably, the soluble metal salt solution in the step 2) comprises one or more mixed solutions of Pt salt, Au salt, Ru salt, Rh salt, Fe salt, Co salt, Ni salt, Pd salt and Ag salt, and the soluble metal salt solution is 0.005-5 mol/L.

Preferably, the ratio of the functional group-rich carbon support powder of step 2) to the soluble metal salt solution is 0.1-3.5: 100; the soaking is carried out at 25-99 deg.C for 5-20 h.

Under the condition of the proportion, the carbon carrier powder rich in functional groups has better adsorption effect.

Preferably, the fumigating treatment in the step 3) is fumigating for 5-100h at 10-220 ℃ in a closed vacuum environment or an inert gas environment.

Preferably, the mercaptan in step 3) comprises one or more of methyl mercaptan, ethyl mercaptan, octyl mercaptan, cyclohexyl mercaptan, cyclopentyl mercaptan, n-dodecyl mercaptan, 2-propyl mercaptan, heptyl mercaptan, phenethyl mercaptan and butyl mercaptan.

Preferably, the calcination in the step 4) is carried out by raising the temperature to 300-700 ℃ at the temperature raising rate of 5-10 ℃/min and carrying out heat preservation calcination for 1-4 h.

Therefore, the invention has the following beneficial effects: according to the invention, metal ions are adsorbed on the carbon material after acid treatment, and then the metal nanocluster catalyst with the sulfur fixed on the surface is prepared by adopting a mercaptan fumigation method, the metal nanoclusters of the catalyst are small in size and good in dispersity, the utilization rate of metal can be effectively improved, and the usage amount of metal in the fuel cell is reduced.

Drawings

Fig. 1 is a TEM image of a carbon-supported metal nanocluster catalyst of example 1 of the present invention.

Fig. 2 is a STEM graph under dark field of the carbon-supported metal nanocluster catalyst of example 1 of the present invention.

Fig. 3 is an XRD pattern of the carbon-supported metal nanocluster catalyst of example 1 of the present invention.

Figure 4 is a graph comparing the ORR catalytic performance of the carbon-supported metal nanocluster catalyst of example 1 of the present invention with a john Matthey type commercial 20% Pt/C catalyst under the same test conditions.

Detailed Description

The invention is further described with reference to specific embodiments.