Method for energy-saving hydrogen production by using binary alloy synthesized by rare earth elements under assistance of alcohol

Abstract

The invention belongs to the technical field of catalyst preparation, and relates to efficient preparation of clean energy, in particular to an energy-saving hydrogen production system using a binary alloy catalyst formed by rare earth elements under the assistance of ethanol. The preparation method comprises the following steps: uniformly mixing metal precursors of palladium and lanthanum, molybdenum hexacarbonyl and an n-caprylic acid solvent by adopting a wet chemical synthesis method, carrying out an oil bath reaction for a period of time, separating precipitates, and sequentially washing and drying to obtain the binary alloy catalyst. The improvement and promotion effects of ethanol on a traditional water electrolysis hydrogen production system are researched in an H-shaped electrolytic tank, and it is proved that ethanol-assisted hydrogen production is an efficient and energy-saving hydrogen production mode. The preparation method of the catalyst is simple, has few steps and is simple and convenient to operate. Compared with a Pd metal alkene catalyst and commercial Pd black, the catalyst provided by the invention has more excellent catalytic activity and stability. The hydrogen production mode is more efficient, and energy consumption is greatly reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalytic materials, and particularly relates to the research on an efficient and energy-saving hydrogen production reaction.

Background Art

[0002] Hydrogen (H 2 ) has a high calorific value and energy density and is an environmentally friendly energy source. Among various hydrogen production technologies, water electrolysis is considered a mature and renewable hydrogen production method. However, due to problems such as high energy consumption and low efficiency in the oxygen evolution reaction (OER) at the anode during water electrolysis, the commercial application of water electrolysis and the production of H 2 are greatly restricted. To solve this problem, we found that using molecules such as amines and alcohols that exhibit a low overpotential in the oxidation reaction to replace the OER at the anode can achieve energy-saving hydrogen production. Especially ethanol, due to its low toxicity and high energy density, makes the ethanol oxidation reaction (EOR) an ideal choice to replace OER.

[0003] Rare earth elements (RE) have a special 4f x 5d y 6s z orbital configuration, which can effectively regulate the electronic structure of the catalyst and the electrochemical reaction process, and has unique advantages in hydrogen production. And RE can also regulate the inherent oxygen affinity of metals and significantly optimize the adsorption and desorption processes of reaction intermediates. Based on these insights, it is feasible to construct an alloy catalyst doped with rare earth elements under ethanol-assisted conditions for a hydrogen production electrolysis system.

[0004] The present invention prepares a high-performance catalyst by using a green and friendly wet chemical synthesis method, simplifies the synthesis steps, and reduces the introduction of impurities. The comparison of the electrochemical performance tested under a two-electrode coupling system shows the significant advantages of ethanol-assisted hydrogen production and RE doping, providing a new idea for an efficient and energy-saving hydrogen production strategy.

Summary of the Invention

[0005] [Technical Problem to be Solved]

[0006] Aiming at the deficiencies in the prior art, the present invention provides a method for efficient and energy-saving hydrogen production under ethanol-assisted conditions.

[0007] Technical Solution:

[0008] 1. A synthesis method of a binary PdLa bimetallic nanosheet catalyst, comprising the following steps:

[0009] Weigh two metal precursors, palladium(II) bis(acetylacetonate) and lanthanum(III) tris(acetylacetonate), disperse them in n-octanoic acid, and then continuously sonicate until completely dissolved. Among them, the mass ratio of the palladium to lanthanum precursors is 0 - 4:1; the volume of the n-octanoic acid solvent is 8 mL.

[0010] 2. Add 8 - 12 mg of molybdenum hexacarbonyl to all the above mixtures, add all the above mixtures into a 20 ml glass bottle, and then place it in an oil bath at 60 - 120 °C for reaction for 1 - 5 hours. After the reaction is completed, take it out and let it cool naturally. Centrifuge and wash with n-hexane, collect the precipitate and dry it for later use.

[0011] Preferably, the mass ratio of the palladium to iron precursors described in 1 is 3:1.

[0012] Another object of the present invention is to use the prepared binary alloy catalyst for ethanol-assisted hydrogen production.

[0013] Experimental method for electrocatalytic ethanol-assisted hydrogen production

[0014] Electrochemical measurements were carried out on a CHI 760E electrochemical workstation by three electrodes. First, we need to separately verify the hydrogen evolution reaction (HER) and ethanol oxidation reaction (EOR) performance of PdLa bimetallicene to explore the possibility of its coupled hydrogen production. The PdLa bimetallicene nanosheets (PdLa bimetallicene) were used as the working electrode and loaded on a glassy carbon electrode. The prepared PdLa bimetallicene (5 mg) was dissolved in water (200 μL), ethanol (770 μL), and 5% Nafion solution (20 μL) to prepare a catalyst solution. A novel platinum sheet without surface treatment and a Hg / HgO electrode were used as the counter electrode and reference electrode, respectively. At different potentials, a chronoamperometry curve (i-t) test was carried out for 2 hours to evaluate the activity of PdLa bimetallicene. Subsequently, a coupling performance test was carried out in an H-type electrolytic cell, using carbon paper as the working electrode. The side of the electrolytic cell filled with 1 mol KOH solution was used as the cathode of the electrolytic cell, and the side filled with 1 mol KOH and 1 mol ethanol solution was used as the anode of the electrolytic cell.

[0015] Compared with the prior art, the advantages and beneficial effects of the present invention:

[0016] The preparation method described in the invention is simple, with few steps and easy to operate. The surface chemical composition of the catalyst can be effectively regulated by controlling the addition amounts of the two metals; the prepared flaky binary PdLa catalyst shows excellent catalytic activity during ethanol-assisted hydrogen production and has good application prospects.

Description of the Drawings

[0017] Figure 1 It is the TEM image of the PdLa bimetallicene described in Example 1.

[0018] Figure 2 XRD patterns of PdLa bimetallene and Pd metallene samples.

[0019] Figure 3 Linear sweep voltammograms of as-prepared PdLa bimetallene, Pd metallene and Pd black in 1 mol KOH + 1 mol ethanol solution.

[0020] Figure 4 Linear sweep voltammograms of as-prepared PdLa bimetallene, Pd metallene and Pd black in 1 mol KOH solution.

[0021] Figure 5 Linear sweep voltammograms of as-prepared PdLa bimetallene in 1 mol KOH at the anode of an H-type electrolytic cell with and without the addition of ethanol.

Detailed implementation manners

[0022] Combined with the attached Figures 1-5 and the following examples to further describe the present invention.

[0023] Example 1

[0024] 1. Preparation of binary PdLa bimetallene catalyst

[0025] Add 7.5 mg of Pd(acac) 2 , 2.5 mg of La(acac) 3 , 10 mg of Mo(CO) 6 and 8 mL of n-octanoic acid solvent into a 20 ml glass bottle, and continuously ultrasonicate until completely dissolved. Then place it in an oil bath at 90 °C for 2 h, take it out and let it cool naturally after the reaction. Centrifuge and wash with n-hexane, collect the precipitate and dry it. After dispersing the sample with a mixed solution, drop it on a glassy carbon electrode and dry it to make an electrode.

[0026] Figure 1 Transmission electron micrograph of the binary PdLa bimetallene catalyst in Example 1 of the present invention, showing a flaky structure.

[0027] 2. Ethanol-assisted coupling hydrogen production research

[0028] Electrochemical measurements were carried out on a CHI 760E electrochemical workstation using a three-electrode system. The PdLa bimetallicene was used as the working electrode and loaded on carbon paper. The prepared PdLa bimetallicene (5 mg) was dissolved in water (200 μL), ethanol (770 μL), and 5% Nafion solution (20 μL) to prepare the catalyst solution. A novel platinum foil without surface treatment and a Hg / HgO electrode were used as the counter electrode and reference electrode, respectively. Chronoamperometry (i-t) tests were performed for 2 h at different potentials to evaluate the activity of PdLa bimetallicene. Under the conditions of 0.43 V, 1 M KOH, and 0.1 M glycerol electrolyte, all current density data were obtained by normalizing the current data to the geometric surface area of the carbon paper.

[0029] Example 2

[0030] 1. Preparation of Pd metallene catalyst

[0031] 7.5 mg of Pd(acac) 2 , 10 mg of Mo(CO) 6 and 8 mL of n-octanoic acid solvent were added to a 20 ml glass bottle and sonicated continuously until completely dissolved. Then it was placed in an oil bath at 90 °C for 2 h, and after the reaction was completed, it was taken out and cooled naturally. It was centrifuged and washed with n-hexane, and the precipitate was collected and dried. After the sample was dispersed with a mixed solution, it was dropped on a glassy carbon electrode and dried to make an electrode.

[0032] 2. Study on electrocatalytic glycerol oxidation

[0033] Electrochemical measurements were carried out on a CHI 760E electrochemical workstation using a three-electrode system. The PdFe bimetallicene nanosheets (PdFe bimetallicene) were used as the working electrode and loaded on carbon paper. 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 novel platinum foil without surface treatment and a Hg / HgO electrode were used as the counter electrode and reference electrode, respectively. Chronoamperometry (i-t) tests were performed for 2 h at different potentials to evaluate the activity of PdFe bimetallicene. Under the conditions of 0.43 V, 1 M KOH, and 0.1 M glycerol electrolyte, all current density data were obtained by normalizing the current data to the geometric surface area of the carbon paper.

[0034] Figure 2XRD patterns of the binary PdLa bimetallic en catalyst and the Pd monometallic en catalyst described in Embodiments 1 and 2 of the present invention. It can be seen that the diffraction peaks of the Pd monometallic en catalyst correspond to the (111), (200), (220), and (311) crystal planes of pure Pd, respectively. The 2θ values of the binary PdLa bimetallic en catalyst are shifted, indicating that the La element has been successfully introduced.

[0035] Figure 3 Linear sweep voltammograms of different catalysts in 1 mol KOH and 1 mol ethanol solution. It can be seen that the prepared binary PdLa bimetallic en catalyst has the best electrochemical performance.

[0036] Figure 4 Linear sweep voltammograms of different catalysts in 1 M KOH solution. It can be seen that the current of the prepared binary PdLa bimetallic en catalyst reaches 10 mA cm -2 The required overpotential is the lowest.

[0037] Figure 5 Linear sweep voltammograms of the prepared PdLa bimetallic en in the anode of an H-type electrolytic cell in 1 mol KOH with and without the addition of ethanol. It can be seen that after the addition of ethanol, the current of the coupled system is significantly increased and the hydrogen evolution performance is enhanced, proving that ethanol-assisted hydrogen production is a more energy-efficient and efficient hydrogen production method compared to water electrolysis hydrogen production.

Claims

1. A method for using a binary alloy formed by rare earth elements for ethanol-assisted hydrogen production, characterized in that Using ethanol oxidation reaction (EOR) instead of the oxidation reaction (OER) at the electrolytic water anode can greatly reduce energy consumption and improve hydrogen production efficiency compared to traditional water electrolysis hydrogen production. The method mainly includes the following steps: (1) Adding di(acetylacetonate)palladium(II) and tri(acetylacetonate)lanthanum(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 binary PdLa bimetallic olefin catalyst.

2. The method for preparing a binary PdLa bimetallic olefin 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.

3. The method for preparing the binary PdLa bimetallic olefin catalyst according to claim 1, characterized in that The mass of molybdenum hexacarbonyl in step (2) is 8-12 mg.

4. The method for preparing the binary PdLa bimetallic olefin catalyst according to claim 1, characterized in that The oil bath temperature in step (3) is 60-120°C.

5. The method for preparing the binary PdLa bimetallic olefin catalyst according to claim 1, characterized in that The reaction time of step (4) is 1-5 hours.

6. The binary PdLa bimetallic olefin catalyst prepared by the method according to any one of claims 1 to 5. Similarly, any system can be applied by replacing La with other rare earth elements.

7. The binary PdLa bimetallic olefin catalyst according to claim 6, characterized in that The molar ratio of palladium to lanthanum is 2:

1.

8. Use of the binary PdLa bimetallic olefin catalyst according to claim 6 or 7, characterized in that The binary PdLa bimetallic olefin catalyst is used for energy-saving hydrogen production assisted by electrocatalytic ethanol.

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