Preparation method of bimetallic alkene catalyst for electro-catalysis glycerol oxidation

Abstract

The invention belongs to the technical field of catalyst preparation, and relates to a binary metal catalyst, in particular to preparation of a binary metal catalyst for efficiently generating glycollic acid. A one-step synthesis method is adopted, metal precursors of palladium and iron, molybdenum carbonyl and an n-caprylic acid solvent are evenly mixed, after an oil bath reaction is carried out for a period of time, precipitates are separated, and washing and drying are carried out in sequence, so that the flaky binary alloy catalyst can be obtained. The preparation method disclosed by the invention is simple, few in steps and simple and convenient to operate. The prepared binary PdFe bimetallic alkene catalyst has more excellent catalytic activity and stability than a monometal Pd catalyst and commercial Pd black in the aspect of electro-catalysis glycerol oxidation.

Description

[Technical field]

[0001] The invention belongs to the technical field of catalytic materials, and in particular relates to research on a binary metal catalyst for efficient glycerol oxidation. [Background technology]

[0002] As the widespread use of fossil fuels has caused environmental pollution and energy crisis, the development and utilization of clean energy and renewable energy have received increasing attention. Biomass, as a rich source of renewable hydrocarbons, is an indispensable component of sustainable energy solutions. Glycerol, as a major by-product of the biodiesel and bioethanol industries, has a major challenge due to its global oversupply. Therefore, it is urgent to explore effective ways to develop and utilize glycerol resources. Adding metals (Ni, Co, Fe, Cu) to Pd catalysts can effectively improve the catalytic activity and stability of alcohol oxidation by means of electronic effects and bifunctional mechanisms.

[0003] The application of electrochemical oxidation in the biomass glycerol oxidation reaction (GOR) can convert glycerol into high-value products such as glycolic acid (GA). The market size of GA is steadily growing with its increasing applications in industries such as daily chemicals, cosmetics, textiles, and pharmaceuticals, and is expected to reach US$531.5 million by 2027. However, the presence of multiple hydroxyl groups in glycerol poses challenges to the efficiency and selectivity of GOR. This is due to insufficient OH- supply and competing side reactions such as oxygen evolution reaction. Based on these insights, it is feasible to construct an electrolysis system to convert low-value glycerol into high-value chemicals. Therefore, exploring and developing an efficient electrocatalyst is key to convert glycerol into high-value products.

[0004] The present invention adopts a green and friendly one-step strategy to prepare a high-performance catalyst, simplifies the synthesis steps, and reduces the introduction of impurities. The prepared PdFe bimetallic exhibits higher electrocatalytic activity and better durability. [Summary of the invention]

[0005] [Technical issues to be solved]

[0006] In view of the deficiencies in the prior art, the present invention provides a method for preparing a binary PdFe catalyst.

[0007] One purpose of the present invention is to uniformly mix metal precursors of palladium and iron and a reducing agent, molybdenum hexacarbonyl, with an octanoic acid solvent, and react in an oil bath for a period of time to obtain a flaky binary PdFe catalyst.

[0008] Technical solution:

[0009] A method for synthesizing a binary PdFe catalyst comprises the following steps:

[0010] 1. Weigh two metal precursors, di(acetylacetonate)palladium(II) and tri(acetylacetonate)iron(III), disperse them in octanoic acid, and then continue to sonicate until completely dissolved. The mass ratio of the palladium to iron precursor is 0-4:1; the volume of the octanoic acid solution is 6-12 mL.

[0011] 2. Add 8-12 mg of molybdenum hexacarbonyl to the above mixture, add the above mixture to a 20 ml glass bottle, and then place it in an oil bath at 60-120°C for 1-5 hours. After the reaction is completed, take it out and cool it naturally. Wash it by centrifugation with n-hexane, collect the precipitate and dry it for later use.

[0012] Preferably, the mass ratio of palladium to iron precursor described in 1 is 3:1.

[0013] 1, the volume of the n-octanoic acid solvent is 8 ml.

[0014] Another object of the present invention is to use the prepared flaky binary alloy catalyst for electrocatalytic glycerol oxidation.

[0015] Experimental Methods for Electrocatalytic Glycerol Oxidation

[0016] Electrochemical measurements were performed on a CHI 760E electrochemical workstation using three electrodes. PdFe bimetallic ene nanosheets (PdFe bimetallic ene) were loaded on carbon paper as the working electrode. The prepared PdFe bimetallic ene (5 mg) was dissolved in water (200 μL), ethanol (770 μL) and 5% Nafion solution (20 μL) to prepare the catalyst ink. A new platinum sheet without surface treatment and a Hg / HgO electrode were used as the counter electrode and reference electrode, respectively. Chronoamperometry (it) tests were performed for 2 h at different potentials to evaluate the activity of PdFe bimetallic ene.

[0017] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0018] The preparation method described in the invention is simple, has few steps, and is easy to operate. The surface chemical composition of the catalyst can be effectively regulated by controlling the amount of two metals added. The flaky binary PdFe catalyst prepared by the invention has excellent activity in glycerol oxidation and has good application prospects.

Brief Description of the Drawings

[0019] Figure 1 This is the TEM image of the binary PdFe catalyst described in Example 1.

[0020] Figure 2 This is the XRD pattern of the PdFe catalyst sample.

[0021] Figure 3This is a linear scanning diagram of the prepared PdFe bimetallic ene, Pd metallic ene and Pd black in 1M KOH + 0.1M glycerol solution.

[0022] Figure 4 is the Faradaic efficiency of PdFe bimetallate to generate glycolic acid in 1M KOH + 0.1M glycerol solution. [Specific implementation method]

[0023] Combined with Figure 1-4 The present invention is further described with reference to the following examples.

[0024] Example 1

[0025] 1. Preparation of binary PdFe catalyst

[0026] 7.5 mg Pd(acac) 2 、2.5mg Fe(acac) 3 , 10mg Mo(CO) 6 Add 8mL of n-octanoic acid solvent into a 20ml glass bottle and continue ultrasonication until completely dissolved. Then place in an oil bath at 90℃ for 2h. After the reaction is completed, take out and cool naturally. Wash with n-hexane by centrifugation, collect the precipitate and dry it. After dispersing the sample with the mixed solution, drop it on the carbon cloth electrode and dry it to make an electrode.

[0027] Figure 1 This is a transmission electron microscope image of the flaky binary PdFe catalyst in Example 1 of the present invention, showing a flaky structure.

[0028] 2. Study on electrocatalytic glycerol oxidation

[0029] Electrochemical measurements were performed on a CHI 760E electrochemical workstation using three electrodes. PdFe bimetallicene nanosheets (PdFe bimetallicene) were loaded on carbon paper as the working electrode. The prepared PdFe bimetallicene (5 mg) was dissolved in water (200 μL), ethanol (770 μL) and 5% Nafion solution (20 μL) to prepare the catalyst ink. A new platinum foil and Hg / HgO electrode without surface treatment were used as the counter electrode and reference electrode, respectively. Chronoamperometric (it) tests were performed for 2 h at different potentials to evaluate the activity of PdFe bimetallicene. All current density data were obtained by normalizing the current data to the geometric surface area of ​​the carbon paper under the conditions of 0.43 V, 1 M KOH and 0.1 M glycerol electrolyte.

[0030] Example 2

[0031] 1. Preparation of Pd flake catalyst

[0032] 7.5 mg Pd(acac) 2 、10mg Mo(CO) 6 Add 8mL of n-octanoic acid solvent into a 20ml glass bottle and continue ultrasonication until completely dissolved. Then place it in an oil bath at 90℃ for 2h. After the reaction is completed, take it out and cool it naturally. Wash it by centrifugation with n-hexane, collect the precipitate and dry it. After dispersing the sample with the mixed solution, drop it on the carbon cloth and dry it to make an electrode.

[0033] 2. Study on electrocatalytic glycerol oxidation

[0034] Electrochemical measurements were performed on a CHI 760E electrochemical workstation using three electrodes. PdFe bimetallicene nanosheets (PdFe bimetallicene) were loaded on carbon paper as the working electrode. The prepared PdFe bimetallicene (5 mg) was dissolved in water (200 μL), ethanol (770 μL) and 5% Nafion solution (20 μL) to prepare the catalyst ink. A new platinum foil and Hg / HgO electrode without surface treatment were used as the counter electrode and reference electrode, respectively. Chronoamperometric (it) tests were performed for 2 h at different potentials to evaluate the activity of PdFe bimetallicene. All current density data were obtained by normalizing the current data to the geometric surface area of ​​the carbon paper under the conditions of 0.43 V, 1 M KOH and 0.1 M glycerol electrolyte.

[0035] Figure 2 2 and 3. The XRD patterns of the flaky binary PdFe catalyst and the flaky Pd catalyst described in Examples 1 and 2 of the present invention show that the diffraction peaks of the flaky Pd catalyst correspond to the (111), (200), (220) and (311) crystal planes of pure Pd, respectively, and the 2θ value of the flaky binary PdFe catalyst is shifted, indicating that Fe is successfully introduced.

[0036] Figure 3 Linear scanning diagrams of different catalysts in 1M KOH and 0.1M glycerol solutions. It can be seen that the prepared sheet-like binary PdFe catalyst has the best electrochemical performance.

[0037] Figure 4 Figure 2 is the Faradaic efficiency of the binary PdFe flake catalyst for the production of glycolic acid in 1 M KOH and 0.1 M glycerol solution at different potentials.

Claims

1. A method for preparing a bimetallic olefin catalyst for electrocatalytic glycerol oxidation, characterized in that A unique sheet-like structure is formed and used to electrocatalyze glycerol to produce glycolic acid, comprising the following steps: (1) Adding di(acetylacetonate)palladium(II) and tri(acetylacetonate)iron(III) into an octanoic acid solution and dissolving them by ultrasonication; (2) adding molybdenum hexacarbonyl and stirring; (3) placing the reaction mixture in an oil bath; (4) After the solution obtained in step (3) is allowed to stand and cool, the precipitate is separated and washed and dried in sequence to obtain the flaky binary PdFe catalyst.

2. The method for preparing a flaky binary PdFe catalyst according to claim 1, characterized in that: The volume of the octanoic acid solution in step (1) is 6-12 mL.

3. The method for preparing a flaky binary PdFe catalyst according to claim 1, characterized in that: The mass ratio of di(acetylacetonate)palladium(II) to tri(acetylacetonate)iron(III) in step (1) is 0-4:

1.

4. The method for preparing a flaky binary PdFe catalyst according to claim 1, characterized in that: The mass of molybdenum hexacarbonyl in step (2) is 8-12 mg.

5. The method for preparing a flaky binary PdFe catalyst according to claim 1, characterized in that: The oil bath temperature in step (3) is 60-120°C.

6. The method for preparing a flaky binary PdFe catalyst according to claim 1, characterized in that: The reaction time of step (4) is 1-5 hours.

7. A sheet-like binary PdFe catalyst prepared according to the method of any one of claims 1 to 6.

8. The sheet-like binary PdFe catalyst according to claim 7, characterized in that: The molar ratio of palladium to iron is 2:

1.

9. Use of the flaky binary PdFe catalyst according to claim 7 or 8, characterized in that: The flaky binary PdFe catalyst is used for electrocatalytic oxidation of glycerol to produce glycolic acid.

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