Preparation method of copper-based catalytic electrode for electro-catalysis hydrogenation of 5-hydroxymethylfurfural

Abstract

The invention belongs to the technical field of electrochemical catalysis and efficient conversion of biomass resources, and particularly relates to a preparation method of a copper-based catalytic electrode for electro-catalysis hydrogenation of 5-hydroxymethylfurfural. The preparation method comprises the following steps: stirring Cu (NO3) 2, DMF, dopamine hydrochloride, deionized water, absolute ethyl alcohol and triethanolamine, centrifuging, washing, drying, dispersing the obtained Dopamine-Cu catalyst powder in absolute ethyl alcohol, performing ultrasonic treatment, dripping on pretreated carbon paper, and drying to obtain the Dopamine-Cu catalytic electrode. The Dopamine-Cu catalytic electrode can be used for directionally converting 5-hydroxymethylfurfural (HMF) into 2, 5-bis (hydroxymethyl) furan (DHMF) in an electrocatalytic reduction system. According to the technology, electrochemical water decomposition hydrogen production and organic hydrogenation reaction are coupled, so that a green hydrogenation path taking water as a hydrogen source is innovatively realized. In addition, the preparation process is zero in carbon emission and free of by-product pollution, and accords with the green chemical principle.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalytic and efficient conversion of biomass resources, and specifically relates to a preparation method of a copper-based catalytic electrode for electrocatalytic hydrogenation of 5-hydroxymethylfurfural. Background Art

[0002] With the increasing depletion of fossil fuels and the enhancement of environmental awareness, it has become an urgent task to find renewable and environmentally friendly sources of energy and chemicals. 5-Hydroxymethylfurfural (HMF), as an important biomass-derived platform molecule, its hydrogenation product 2,5-bis(hydroxymethyl)furan (DHMF) has wide applications in fields such as polyester materials and polyurethane foams, and the market demand is strong. However, traditional hydrogenation methods have safety hazards such as harsh reaction conditions and the use of flammable and explosive hydrogen as the hydrogen source, and the cost is high. As an emerging method, electrocatalytic technology provides a new solution for the hydrogenation reduction of HMF with its mild reaction conditions, safe hydrogen source (H2O) and environmental friendliness. Through electrocatalysis, the efficient conversion of HMF to DHMF can be achieved at room temperature and atmospheric pressure, avoiding the risks of hydrogen storage and transportation in traditional methods. The present invention synthesizes a copper-based catalytic electrode simply, electro-reduces HMF to DHMF in an alkaline electrolyte, and the Faraday efficiency reaches 80%, showing excellent catalytic performance. Summary of the Invention

[0003] The present invention provides a preparation method of a copper-based catalytic electrode and the application of an electrocatalytic reduction system based on the copper-based catalytic electrode in the directional conversion of 5-hydroxymethylfurfural (HMF) to 2,5-bis(hydroxymethyl)furan (DHMF). This technology innovatively realizes a green hydrogenation path using water as the hydrogen source by coupling electrochemical water splitting to produce hydrogen with organic hydrogenation reactions, breaking through the limitations of traditional thermal catalysis relying on high-pressure hydrogen and noble metal catalysts, and providing a new solution for the conversion of biomass-based platform molecules into high-value-added chemicals.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A preparation method of a copper-based catalytic electrode for electrocatalytic hydrogenation of 5-hydroxymethylfurfural, comprising the following steps:

[0006] 1) Pretreatment of carbon paper: Cut the carbon paper into 0.5×2 cm, soak it in dilute nitric acid, rinse it with deionized water, dry it, and calcine it in a muffle furnace;

[0007] 2) Take 0.226 g of Cu(NO3)2, add 40 mL of DMF, 0.091 g of dopamine hydrochloride, 2 mL of deionized water, 1 mL of absolute ethanol and 1 mL of triethanolamine, stir, then centrifuge, wash, and dry to obtain Dopamine-Cu catalyst powder;

[0008] 3) Take 5 mg of Dopamine-Cu catalyst powder, disperse it in 2 mL of absolute ethanol, ultrasonicate for 5 min, drop it on the pretreated carbon paper, and dry it to obtain a Dopamine-Cu catalytic electrode.

[0009] Further, in the above preparation method, in step 1), the soaking time in dilute nitric acid is 30 min.

[0010] Further, in the above preparation method, in step 1), the calcination conditions are: calcination at 300 °C for 5 h.

[0011] Further, in the above preparation method, in step 2), the stirring time is 24 h.

[0012] Further, in the above preparation method, in step 2), the drying conditions are: drying at 60 °C overnight.

[0013] Further, in the above preparation method, in step 3), the drying conditions are: drying at 60 °C for 2 h.

[0014] Application of the Dopamine-Cu catalytic electrode prepared by the preparation method described in any one of the above in the electrocatalytic hydrogenation reduction of 5-hydroxymethylfurfural to prepare DHMF.

[0015] Further, in the above application, the method is as follows: Using water as the hydrogen source, adopting an H-type electrolytic cell, adding 20 mL of electrolyte to the anode electrolytic cell and the cathode electrolytic cell respectively, connecting the cathode and the anode electrolytic cells through a proton exchange membrane, and adding 0.05 g of 5-hydroxymethylfurfural to the cathode electrolytic cell. The Dopamine-Cu catalytic electrode is used as the working electrode, the carbon rod is used as the counter electrode, the Ag / AgCl electrode is used as the reference electrode, the rotation speed is 550 r / min, the time is 1 h, and electrocatalytic hydrogenation reduction of 5-hydroxymethylfurfural to prepare DHMF is carried out in the cathode electrolytic cell.

[0016] Furthermore, in the above application, the electrolyte is 1 M aqueous KHCO3 solution.

[0017] The beneficial effects of the present invention are as follows:

[0018] 1. The present invention in-situ generates active hydrogen species by electrolyzing water, completely avoiding the safety risks of high-pressure hydrogen storage and transportation. The reaction process only requires normal temperature and pressure conditions, greatly reducing equipment investment and operating energy consumption.

[0019] 2. The copper-based catalytic electrode of the present invention exhibits excellent catalytic activity and selectivity, achieving a Faraday efficiency of 80% for DHMF in alkaline electrolyte. Its catalytic performance is comparable to that of noble metal systems, and the raw material cost is much lower than that of traditional palladium / platinum catalysts.

[0020] 3. The preparation process of the present invention has zero carbon emissions and no by-product pollution, meeting the principles of green chemistry. The technology of the present invention has important industrial value for promoting the replacement of fossil fuels with renewable energy and constructing a high-value-added chemical manufacturing system. Description of the Drawings

[0021] Figure 1 It is a scanning electron microscope image of the Dopamine-Cu catalyst.

[0022] Figure 2 It is an X-ray diffraction pattern (XRD) of the Dopamine-Cu catalyst.

[0023] Figure 3 It is a linear sweep voltammogram of electrocatalytic HMF reduction by the Dopamine-Cu catalytic electrode and the CP catalytic electrode.

[0024] Figure 4 It is an i-t curve of electrocatalytic HMF reduction by the Dopamine-Cu catalytic electrode. Detailed Description of the Invention

[0025] Example 1 Preparation of the Dopamine-Cu Catalytic Electrode

[0026] 1) Pretreatment of the carbon paper: Cut the purchased carbon paper into 0.5×2 cm, soak it in dilute nitric acid for 30 min, rinse it with deionized water until clean, dry it, and calcine it in a muffle furnace at 300 °C for 5 h;

[0027] 2) Take 0.226 g of Cu(NO3)2, add 40 mL of DMF, 0.091 g of dopamine hydrochloride, 2 mL of deionized water, 1 mL of absolute ethanol, and 1 mL of triethanolamine. After stirring for 24 h, centrifuge, wash, and dry overnight at 60 °C to obtain the Dopamine-Cu catalyst powder;

[0028] 3) Disperse 5 mg of the Dopamine-Cu catalyst powder in 2 mL of absolute ethanol, ultrasonicate for 5 min, drop it on the pretreated carbon paper, and dry at 60 °C for 2 h to prepare the Dopamine-Cu catalytic electrode.

[0029] From Figure 1 in the scanning electron microscope image (SEM), it can be seen that the boundaries between the Dopamine-Cu catalyst particles are not very clear, showing obvious agglomeration characteristics. The surface is rough, the particles are irregular, with irregular small holes and depressions, increasing the specific surface area and facilitating the adsorption and reaction of reactants. From Figure 2It can be seen from the XRD pattern that the peak at 21.5° corresponds to the characteristic peak of C (JCPDS#NO.50-0927), and no typical sharp characteristic peak of Cu is shown, indicating that amorphous or low-coordination copper polymers may have been formed.

[0030] Preparation of the CP catalytic electrode in Comparative Example 1

[0031] The purchased carbon paper was cut into 0.5×2 cm, soaked in dilute nitric acid for 30 min, rinsed thoroughly with deionized water, dried, and calcined in a muffle furnace at 300 °C for 5 h.

[0032] Example 2 Electrochemical performance test of the Dopamine-Cu catalytic electrode

[0033] (I) Electrochemical performance test of the Dopamine-Cu catalytic electrode.

[0034] The electrochemical performance test was carried out using an H-type electrolytic cell and a three-electrode working system. Using 1 M KHCO3 aqueous solution as the electrolyte, 20 mL of the electrolyte was added to the anode chamber and the cathode chamber respectively, and 0.05 g of 5-hydroxymethylfurfural was added to the cathode chamber. The Dopamine-Cu catalytic electrode was used as the working electrode, the carbon rod as the counter electrode, and the Ag / AgCl electrode as the reference electrode. The electrolytic cell was sealed, and nitrogen was introduced into it for 30 min to remove the oxygen in the solution, and then the electrochemical performance test was carried out to obtain the LSV curve of the Dopamine-Cu catalytic electrode, as shown by the solid line in Figure 3 The voltage used in this test was based on the standard hydrogen electrode potential.

[0035] The model of the electrochemical workstation used in this test was CHI 760E, and the linear sweep voltammetry scan parameters were a rotation rate of 1600 rpm and a scan rate of 50 mV s -1 .

[0036] (II) Electrochemical performance test of the CP catalytic electrode.

[0037] The electrochemical performance test was carried out using an H-type electrolytic cell and a three-electrode working system. Using 1 M KHCO3 aqueous solution as the electrolyte, 20 mL of the electrolyte was added to the anode chamber and the cathode chamber respectively, and 0.05 g of 5-hydroxymethylfurfural was added to the cathode chamber. The CP catalytic electrode was used as the working electrode, the carbon rod as the counter electrode, and the Ag / AgCl electrode as the reference electrode. The electrolytic cell was sealed, and nitrogen was introduced into it for 30 min to remove the oxygen in the solution, and then the electrochemical performance test was carried out to obtain the LSV curve of the CP catalytic electrode, as shown by the dashed line in Figure 3 The voltage used in this test was based on the standard hydrogen electrode potential.

[0038] In this test, the model of the electrochemical workstation is CHI 760E, and the linear sweep voltammetry scanning parameters are a rotation rate of 1600 rpm and a scanning rate of 50 mV s -1 .

[0039] The performance of the Dopamine-Cu catalytic electrode was tested electrochemically, and by comparing Figure 3 the LSV curves, it can be seen that when the Dopamine-Cu catalytic electrode is at -1.4 V vs. RHE, the current density can reach 13 mA / cm 2 , and when the CP catalytic electrode is at -1.4 V vs. RHE, the current density is 5 mA / cm 2 . At -1.4 V vs. RHE, the current density of the Dopamine-Cu catalytic electrode is about 2.6 times that of the CP catalyst. In this test, the voltage used is based on the standard hydrogen electrode potential. By comparison, it can be found that the Dopamine-Cu catalytic electrode has a good catalytic effect on the reduction of HMF.

[0040] Example 3 Chronoamperometry Test of Dopamine-Cu Catalytic Electrode

[0041] Chronoamperometry test (IT): Using water as the hydrogen source and the Dopamine-Cu catalytic electrode as the working electrode, electrocatalytic selective reduction of HMF to prepare DHMF was carried out through a long-term chronoamperometry test (IT). Voltage of the IT experiment: As can be seen from the LSV curve, when the Dopamine-Cu catalytic electrode and the CP catalytic electrode are at -1.4 V vs. RHE, the current density difference is the largest. Therefore, the IT experiment was carried out at -1.4 V vs. RHE; Electrolytic cell and electrolyte of the IT experiment: An H-type electrolytic cell was used. In the cathode electrolytic cell, the electrolyte was: 20 mL of 1 M KHCO3 aqueous solution; the electrolyte in the anode electrolytic cell was 20 mL of 1 M KHCO3 aqueous solution. The cathode and anode electrolytic cells were connected by a proton exchange membrane. The electrocatalytic reaction was carried out in the cathode electrolytic cell, and the electrolysis substrate was 0.05 g of 5-hydroxymethylfurfural; Working electrode of the IT experiment: Dopamine-Cu catalytic electrode; Counter electrode of the IT experiment: Carbon rod; Reference electrode of the IT experiment: Ag / AgCl electrode; The IT experiment time was 1 h and the rotation speed was 550 r / min. The i-t curve of the Dopamine-Cu catalytic electrode was obtained, as Figure 4 .

[0042] In this experiment, the model of the electrochemical workstation is CHI 760E.

[0043] Detection of DHMF product: The electrolyte after the 1 h IT experiment was subjected to high performance liquid chromatography detection to calculate the Faraday efficiency. The Faraday efficiency of DHMF can reach 80%.

[0044] It can be seen from Figure 4 that within the time period of 0 - 1.00 h, the current density remains basically stable, stabilizing at about 11 mA / cm 2 or so, without obvious fluctuations, indicating that the Dopamine-Cu catalytic electrode has good stability within this test time range and can maintain relatively stable electrochemical reaction performance.

Claims

1. A preparation method of a copper-based catalytic electrode for electrocatalytic hydrogenation of 5-hydroxymethylfurfural, characterized in that, It includes the following steps: 1) Pretreatment of carbon paper: Cut the carbon paper into 0.5×2 cm, soak it in dilute nitric acid, rinse it thoroughly with deionized water, dry it, and calcine it in a muffle furnace; 2) Take 0.226 g of Cu(NO3)2, add 40 mL of DMF, 0.091 g of dopamine hydrochloride, 2 mL of deionized water, 1 mL of absolute ethanol and 1 mL of triethanolamine, stir and then centrifuge, wash, and dry to obtain Dopamine-Cu catalyst powder; 3) Take 5 mg of Dopamine-Cu catalyst powder, disperse it in 2 mL of absolute ethanol, sonicate for 5 min, drop it on the pretreated carbon paper, and dry to obtain a Dopamine-Cu catalytic electrode.

2. The preparation method according to claim 1, characterized in that, In step 1), the soaking time in dilute nitric acid is 30 min.

3. The preparation method according to claim 1, characterized in that, In step 1), the calcination conditions are: calcination at 300 °C for 5 h.

4. The preparation method according to claim 1, wherein In step 2), the stirring time is 24 h.

5. The preparation method according to claim 1, characterized in that, In step 2), the drying conditions are: drying at 60 °C overnight.

6. The preparation method according to claim 1, wherein In step 3), the drying conditions are: drying at 60 °C for 2 h.

7. Application of the copper-based catalytic electrode prepared by the preparation method according to any one of claims 1-6 in the electrocatalytic hydrogenation reduction of 5-hydroxymethylfurfural to prepare DHMF.

8. The application according to claim 7, wherein The method is as follows: Using water as the hydrogen source, adopt an H-type electrolytic cell, add 20 mL of electrolyte to the anode electrolytic cell and the cathode electrolytic cell respectively, connect the cathode and anode electrolytic cells through a proton exchange membrane, and add 0.05 g of 5-hydroxymethylfurfural to the cathode electrolytic cell. The Dopamine-Cu catalytic electrode is used as the working electrode, the carbon rod is used as the counter electrode, the Ag / AgCl electrode is used as the reference electrode, the rotation speed is 550 r / min, the time is 1 h, and the electrocatalytic hydrogenation reduction of 5-hydroxymethylfurfural to prepare DHMF is carried out in the cathode electrolytic cell.

9. The application according to claim 8, wherein The electrolyte is 1 M aqueous KHCO3 solution.

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