Preparation method of bowl-shaped binary metal catalyst acting on glycerol oxidation

Abstract

The invention belongs to the technical field of catalyst preparation, and relates to a bowl-shaped binary PtCo bimetallic catalyst, in particular to a preparation method and application of bowl-shaped binary PtCo bimetallic. The preparation method comprises the following steps: uniformly mixing precursors of two metals in an n-caprylic acid solution containing molybdenum hexacarbonyl by adopting a one-step synthesis method, carrying out an oil bath reaction for a period of time, separating precipitates, and sequentially washing and drying to obtain the bowl-shaped binary bimetallic catalyst. The preparation method disclosed by the invention is simple, few in steps and simple and convenient to operate. The prepared bowl-shaped binary PtCo bimetallic catalyst has excellent catalytic activity and stability in the aspect of electro-catalysis glycerol oxidation in an alkali environment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalytic materials, and particularly relates to a study of a bowl-shaped binary metal catalyst for glycerol oxidation. BACKGROUND

[0002] With the vigorous development of the biodiesel industry, the production of glycerol, as the main by-product, has increased dramatically, and seeking efficient and high-value conversion routes has become one of the key challenges in the field of biomass refining. Among the many downstream products of glycerol, glycerol oxidation products (such as dihydroxyacetone, glyceric acid, tartaric acid, etc.) are of great concern due to their important application value in food, medicine, cosmetics and fine chemicals. However, the selective oxidation pathway of glycerol molecules is complex, involving multiple parallel and serial reactions, and achieving high selectivity of target products (especially high-value-added products) has always been a core difficulty of the reaction.

[0003] Currently, noble metals (such as Pt, Pd, Au) and their alloy catalysts exhibit good activity in glycerol oxidation, but generally face problems such as high cost, difficulty in selectivity control, and easy poisoning and deactivation by intermediate products. To overcome these challenges, research focus has gradually shifted to the design of binary metal (binary metal) catalysts. By introducing a second metal component (such as Bi, Sb, Sn, Cu, Ni, etc.), the electronic effect (ligand effect) and geometric effect (synergistic effect) between the two metals can significantly regulate the electronic structure of the active site and optimize the adsorption / desorption behavior of oxygen-containing intermediates, thereby improving the selectivity of specific target products and the resistance of the catalyst to poisoning. In recent years, precise control of the nanostructure morphology of the catalyst has been proven to be an effective strategy to further improve catalytic performance. Among them, bowl-shaped nanostructures are favored due to their unique physical and chemical properties.

[0004] The application simplifies the synthesis steps and reduces the introduction of impurities by using molybdenum hexacarbonyl as a reducing agent to prepare high-performance catalysts using a green and friendly one-step method strategy. The prepared binary metal catalysts exhibit high electrocatalytic activity and good durability in the glycerol oxidation process. SUMMARY

[0005] [Technical problems to be solved] In view of the deficiencies in the prior art, the application provides a preparation method of a bowl-shaped binary PtCo bimetallic catalyst.

[0006] One object of the application is to uniformly mix the metal precursors of platinum and cobalt, the reducing agent molybdenum hexacarbonyl and the n-octanoic acid solvent, and obtain the bowl-shaped binary PtCo bimetallic catalyst through oil bath reaction for a period of time.

[0007] Technical scheme:

[0008] A method for synthesizing a binary PtCo catalyst includes the following steps: 1. Weigh out two metal precursors, bis(acetylacetone)platinum(II) and bis(acetylacetone)cobalt(II), disperse them in octanoic acid, and then sonicate continuously until completely dissolved. The mass ratio of the platinum to cobalt precursors is 0-4:1; the volume of the octanoic acid solution is 6-12 mL.

[0009] 2. Add 8-12 mg of molybdenum hexacarbonyl to all the above mixtures, then add all the mixtures to a 30 mL glass bottle. Place the bottle in an oil bath and react at 60-120°C for 1-5 hours. After the reaction is complete, remove the bottle and allow it to cool naturally. Wash the mixture with n-hexane by centrifugation, collect the precipitate, and dry it for later use.

[0010] Preferably, the mass ratio of the platinum to cobalt precursor described in 1 is 3:1.

[0011] In step 1, the volume of the octanoic acid solvent is 8 ml.

[0012] Another objective of this invention is to use the prepared bowl-shaped binary PtCo catalyst for the electrocatalytic oxidation of glycerol in an alkaline environment.

[0013] Experimental method for electrocatalytic oxidation of glycerol in alkaline environment The prepared catalyst was ultrasonically dispersed in a Nafion mixed solution, then dropped onto carbon cloth and dried at room temperature to form an electrode. The Nafion mixed solution was prepared from ultrapure water, ethanol, and a 5 wt% Nafion solution. A three-electrode electrochemical testing system was constructed using a bowl-shaped binary PtCo bimetallic catalyst dropped onto a carbon cloth electrode as the working electrode, an Hg / HgO electrode as the reference electrode, and a Pt sheet as the counter electrode. The linear scan of the catalyst in alkaline solution was measured. Experimental results showed that the bowl-shaped binary PtCo bimetallic catalyst prepared in this invention exhibits superior electrocatalytic activity compared to single-metal Pt catalysts.

[0014] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: The preparation method described in this invention is simple, involves few steps, and is easy to operate. The surface chemical composition of the catalyst can be effectively controlled by adjusting the amount of the two metals added. The bowl-shaped binary PtCo bimetallic catalyst prepared by this invention exhibits excellent activity in the electrocatalytic oxidation of glycerol (GOR) in an alkaline environment and has good application prospects in the field of biomass fuels. Attached Figure Description

[0015] Figure 1 This is a TEM image of the bowl-shaped binary PtCo bimetallic catalyst described in Example 1.

[0016] Figure 2 This is the energy spectrum of a bowl-shaped binary PtCo bimetallic catalyst.

[0017] Figure 3 The image shows the linear potential scans of the prepared bowl-shaped binary PtCo bimetallic catalyst in solutions containing 1 mol / L KOH, 0.1 mol / L glycerol, and no glycerol.

[0018] Figure 4 The data are Faraday data for a bowl-shaped binary PtCo bimetallic catalyst in a solution containing 1 mol / L KOH and 0.1 mol / L glycerol. Detailed Implementation

[0019] Combined with appendix Figures 1-4 The invention will be further described in the following embodiments.

[0020] Example 1

[0021] 1. Preparation of bowl-shaped binary PtCo bimetallic catalysts 7.5 mg Pt(acac)₂, 2.5 mg Co(acac)₂, 10 mg Mo(CO)₆, and 8 mL of n-octanoic acid solvent were added to a 20 mL glass bottle and sonicated until completely dissolved. The bottle was then placed in an oil bath and reacted at 100 °C for 3 h. After the reaction was complete, the bottle was removed and allowed to cool naturally. The precipitate was washed with n-hexane by centrifugation, collected, and dried.

[0022] Figure 1 The image shown is a transmission electron microscope (TEM) image of the bowl-shaped binary PtCo bis-gold catalyst in Example 1 of this invention, revealing a bowl-shaped structure.

[0023] 2. Study on the electrocatalytic oxidation of glycerol in an alkaline environment A three-electrode electrochemical testing system was constructed using a bowl-shaped binary PtCo catalyst dropped onto a carbon paper electrode as the working electrode, a platinum sheet electrode as the counter electrode, and an Hg / HgO electrode as the reference electrode. Cyclic voltammetry of the catalyst in 1 mol / L KOH solution was tested with a potential window of 0.4–2.0 V and a scan rate of 10 mV / s. Cyclic voltammetry of the catalyst in 1 mol / L KOH solution containing 1 mol / L ethanol was also tested with a potential window of -0.7–0.3 V and a scan rate of 10 mV / s.

[0024] Example 2

[0025] Preparation of bowl-shaped binary PtCo gold catalyst 7.5 mg Pt(acac)₂, 2.5 mg Co(acac)₂, 10 mg Mo(CO)₆, and 8 mL of n-octanoic acid solvent were added to a 20 mL glass bottle and sonicated until completely dissolved. The bottle was then placed in an oil bath and reacted at 100 °C for 3 h. After the reaction was complete, the bottle was removed and allowed to cool naturally. The precipitate was washed with n-hexane by centrifugation, collected, and dried.

[0026] Figure 2 The energy spectrum of the bowl-shaped binary PtCo bis-gold catalyst described in Examples 1 and 2 of this invention shows that the elemental ratio is close to 10:1.

[0027] Figure 3 The figure shows the linear potential scans of the bowl-shaped binary PtCo catalyst in solutions containing 1 mol / L KOH, 0.1 mol / L glycerol, and glycerol-free solutions. It can be seen that the prepared bowl-shaped binary PtCo catalyst exhibits a very small overpotential in the presence of glycerol.

[0028] Figure 4 Faraday data for the oxidation of glycerol to formic acid using a bowl-shaped binary PtCo bis-gold catalyst at potentials of 1.83, 1.88, 1.93, 1.98, and 2.03 V.

Claims

1. A method for preparing a bowl-shaped bimetallic catalyst for glycerol oxidation, comprising the following steps: (1) adding di(acetylacetone) platinum (II) and di(acetylacetone) cobalt (II) into n-octanoic acid solution and ultrasonic dissolving; (2) then adding hexacarbonylmolybdenum and stirring; (3) placing the reaction mixture in an oil bath; (4) after the solution obtained in step (3) is cooled by standing, separating the precipitate and sequentially washing and drying to obtain the bowl-shaped bimetallic PtCo catalyst. The volume of the n-octanoic acid solution in step (1) is 6-12 mL. The mass ratio of di(acetylacetone) platinum (II) and di(acetylacetone) cobalt (II) in step (1) is 0-4:

1. The mass of hexacarbonylmolybdenum in step (2) is 8-12 mg. The temperature of the oil bath in step (3) is 60-120℃.

2. The method for preparing the bowl-shaped binary PtCo bimetallic catalyst according to claim 1, characterized in that, The reaction time in step (4) is 1-5 hours.

3. The method for preparing the bowl-shaped binary PtCo bimetallic catalyst according to claim 1, characterized in that, 7. The bowl-shaped bimetallic PtCo catalyst prepared by the method according to any one of claims 1-6.

4. The method for preparing the bowl-shaped binary PtCo bimetallic catalyst according to claim 1, characterized in that, The molar ratio of platinum and cobalt nPt:nCo is 3:

1.

5. The method for preparing the bowl-shaped binary PtCo bimetallic catalyst according to claim 1, characterized in that, The bowl-shaped bimetallic PtCo catalyst is used for electrocatalytic glycerol oxidation.

6. The method of claim 1, wherein the bowl-shaped PtCo bimetallic catalyst is prepared by the steps of: ​ ​ 8. The bowl-shaped binary PtCo bimetallic catalyst of claim 7, wherein, ​ 9. Use of a bowl-shaped binary PtCo bimetallic catalyst according to claim 7 or 8, characterized in that, ​

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