Electrochemical hydrogenation catalyst, its preparation method and application

Abstract

The present application relates to the field of electrochemical hydrogenation, and in particular to a catalyst for electrochemical hydrogenation, and a preparation method and application thereof.The catalyst for electrochemical hydrogenation comprises Cu nanowires and a modifier loaded on the Cu nanowires, and the modifier is a Keggin-type heteropoly acid and / or heteropoly acid salt.By loading the Keggin-type heteropoly acid and / or heteropoly acid salt on the Cu nanowires, and modifying the Cu nanowires with the Keggin-type heteropoly acid and / or heteropoly acid salt, the overpotential of the catalyst for generating active hydrogen / hydrogen evolution can be greatly reduced, the hydrogen coverage of the catalyst surface can be improved, and thus the reaction activity, selectivity and stability of the catalyst can be improved, so that the catalyst of the present application can be applied to a higher substrate reaction concentration.

Description

Technical Field

[0001] This invention relates to the field of electrochemical hydrogenation, specifically to a catalyst for electrochemical hydrogenation, its preparation method, and its application. Background Technology

[0002] 5-Hydroxymethylfurfural (HMF) is an important platform compound from biomass sources, which can be used as a raw material for the selective hydrogenation of high-value-added 2,5-furandiethanol (BHMF). As a diol compound containing a furan ring, BHMF can be applied to the synthesis of functionalized polyesters, polyethers, resins, and pharmaceutical intermediates.

[0003] Because HMF (hydrogen-methyl-2 ...

[0004] Electrochemical hydrogenation can selectively hydrogenate HMF at room temperature using water as a solvent and protons in the water as the hydrogen source. It is the mildest and most environmentally friendly method. However, the activity and selectivity of currently developed electrocatalysts are still unsatisfactory. To improve the reaction activity, precious metal catalysts are required, resulting in high reaction costs.

[0005] Existing technologies disclose the preparation of BHMF by electrochemical hydrogenation of HMF using copper-based catalysts obtained through the electrochemical reduction of CuO nanowires, with electrocatalytic hydrogenation at a voltage of -0.4V to -0.5V for 2-3 hours. However, the HMF concentration in this reaction is only 50mM, increasing the use of solvents and separation costs. Furthermore, the stability test time for the aforementioned copper-based catalysts in the electrohydrogenation reaction is still relatively short (less than 10 hours). Moreover, this technology does not disclose the selectivity of the reaction for BHMF. It is well known in the art that the electrohydrogenation reaction of HMF not only generates BHMF but may also produce byproducts such as dihydroxymethylfurfural (BHH), 2-methylfurfural (MF), and 2-methylfurfural alcohol (MFA), as shown in the following reaction formula:

[0006]

[0007] Therefore, there is an urgent need to develop an electrochemical hydrogenation catalyst that does not contain precious metals but still has high reactivity and high selectivity and stability at high concentrations. Summary of the Invention

[0008] In view of this, the present invention provides a catalyst for electrochemical hydrogenation to solve the problems that existing electrohydrogenation catalysts have low reactivity, selectivity and stability and are only applicable to low reaction concentrations.

[0009] In a first aspect, the present invention provides a catalyst for electrochemical hydrogenation, comprising: Cu nanowires and a modifier supported on the Cu nanowires, wherein the modifier is a Keggin-type heteropolyacid and / or heteropolyacid salt.

[0010] By loading Keggin-type heteropolyacids and / or heteropolyacid salts onto Cu nanowires, and modifying the Cu nanowires with these types of heteropolyacids and / or heteropolyacid salts, the overpotential for active hydrogen generation / hydrogen evolution of the catalyst can be significantly reduced, and the hydrogen coverage on the catalyst surface can be improved, thereby enhancing the catalyst's reactivity, selectivity, and stability. This allows the catalyst of the present invention to be suitable for higher reaction concentrations.

[0011] In embodiments of the present invention, the Keggin-type heteropolyacid is at least one of phosphomolybdic acid, silicotungstic acid, and phosphotungstic acid.

[0012] In embodiments of the present invention, the Keggin-type heteropolyacid salt is at least one of sodium phosphomolybdate and ammonium phosphotungstate.

[0013] In embodiments of the present invention, the Cu nanowires may be derived from Cu(OH)2 nanowires and / or CuO nanowires.

[0014] In embodiments of the present invention, the mass ratio of the modifier to the Cu nanowires is 0.1% to 10%, preferably 0.5% to 2%.

[0015] In an embodiment of the present invention, the Cu nanowire has a length of 0.5–12 μm and a width of 50–200 nm.

[0016] Secondly, the present invention provides a method for preparing the above-mentioned catalyst for electrochemical hydrogenation, comprising the following steps:

[0017] S1. Dissolve the modifier in an alcohol solvent to form a modifier solution, wherein the modifier is a Keggin-type heteropolyacid and / or heteropolyacid salt;

[0018] S2. Place CuO nanowires and / or Cu(OH)2 nanowires in the modifier solution, soak for a first time, remove, dry, and calcine under the presence of a protective gas or air to obtain a precursor; or place Cu nanowires in the modifier solution, soak for a first time, remove, dry, and calcine under the presence of a protective gas or air to obtain a catalyst.

[0019] S3. The precursor is used as a cathode for electrochemical reduction. The reduced cathode is removed, cleaned, and dried to obtain the catalyst.

[0020] In embodiments of the present invention, the concentration of the modifier solution is 0.3 mmol / L to 2 mmol / L.

[0021] In embodiments of the present invention, the Keggin-type heteropolyacid is at least one of phosphomolybdic acid, silicotungstic acid, and phosphotungstic acid.

[0022] In embodiments of the present invention, the Keggin-type heteropolyacid salt is at least one of sodium phosphomolybdate and ammonium phosphotungstate.

[0023] In embodiments of the present invention, the alcohol solvent is a lower alcohol, such as at least one of methanol, ethanol, and isopropanol.

[0024] In embodiments of the present invention, the first soaking time is 20 min to 4 h, preferably 30 min to 1 h. If the soaking time is too short, the modifier cannot be fully loaded; if the soaking time is too long, more modifier cannot be loaded. Therefore, soaking for 20 min to 4 h is sufficient, and soaking for 30 min to 1 h is more suitable.

[0025] In an embodiment of the present invention, the drying temperature in step S2 is 25°C to 80°C. If the drying temperature is too low, the drying time will be prolonged; if the drying temperature is too high, the modifier solution will evaporate too quickly, reducing the uniformity of the modifier clusters on the material surface. Therefore, drying at 25°C to 80°C is most suitable.

[0026] In embodiments of the present invention, the calcination temperature is 200℃~350℃, the heating rate is 1~5℃ / min, and the time is 1h~5h. The purpose of calcination is to anchor the modifier to the carrier by forming chemical bonds. Therefore, the calcination temperature cannot be too low, otherwise stable chemical bonds will not form; however, the calcination temperature cannot be too high, otherwise the modifier will decompose thermally. The heating rate cannot be too fast, otherwise temperature overshoot will occur; the heating rate cannot be too slow, as this will increase the preparation time.

[0027] In embodiments of the present invention, the protective gas is at least one of nitrogen and argon.

[0028] In an embodiment of the present invention, Cu nanowires can be prepared by high-temperature reduction of Cu(OH)2 nanowires. The reducing atmosphere used is at least one of hydrogen, a hydrogen-argon mixture containing at least 5v% hydrogen, or a hydrogen-nitrogen mixture containing at least 5v% hydrogen. The reduction conditions are reduction at approximately 300°C for 3 hours.

[0029] In an embodiment of the present invention, in step S3, the reduction potential is -0.2V to -0.7V, and the reduction time is 20 min to 1 h. The purpose of electrochemical reduction is to convert CuO into metallic Cu. If the reduction potential is too high, too many hydrogen bubbles will be generated, causing the modifier to detach from the Cu surface. If the reduction potential is too low, the reduction time will be prolonged. Accordingly, the reduction time needs to be controlled between 20 min and 1 h. Too short a time will lead to incomplete reduction, thus affecting the catalytic effect, while too long a reduction time will only waste time and resources.

[0030] In an embodiment of the present invention, in step S3, Ag / AgCl is used as the reference electrode and a platinum electrode is used as the counter electrode. In the H-type electrolytic cell, the cathode and anode electrolytes are both 0.5M PBS solutions with pH=7, and the two are separated by a Nafion 212 proton exchange membrane. The PBS buffer solution is used as the cathode electrolyte not only as an electrolyte, but also to keep the pH value relatively constant.

[0031] Thirdly, the present invention also provides the application of the above-mentioned electrochemical hydrogenation catalyst or the electrochemical hydrogenation catalyst prepared by the above-mentioned preparation method in the catalytic electrohydrogenation of 5-hydroxymethylfurfural to prepare 2,5-furandiethanol.

[0032] Fourthly, the present invention also provides a process for preparing 2,5-furandiethanol, comprising the following steps:

[0033] Using a catalyst as the cathode, the cathode is placed in a cathode electrolyte containing dissolved 5-hydroxymethylfurfural, and an electrochemical hydrogenation reaction is carried out by applying a negative voltage;

[0034] The catalyst is an electrochemical hydrogenation catalyst provided by the first aspect of the present invention or an electrochemical hydrogenation catalyst prepared by the preparation method provided by the second aspect of the present invention.

[0035] The electrochemical hydrogenation reaction of 5-hydroxymethylfurfural using the catalyst of this invention significantly reduces the catalyst overpotential, thereby improving the reaction activity and enhancing the selectivity of 2,5-furandimethyl. It maintains a high Faradaic efficiency even at a 1M HMF concentration and remains stable even after operating at a high current density for nearly 80 hours.

[0036] In an embodiment of the present invention, the electrode area of ​​the cathode is 1 cm². 2 .

[0037] In embodiments of the present invention, the negative voltage is -0.15V to -0.4V (vs RHE). In electrochemical hydrogenation reactions, applying a certain negative voltage can overcome the hydrogenation overpotential. However, if the absolute value of the potential is too low, the hydrogenation reaction cannot be achieved or the current density is too low. Conversely, if the absolute value of the potential is too high, a serious hydrogen evolution side reaction may occur.

[0038] In an embodiment of the invention, the coulomb number of the electrochemical hydrogenation reaction is 101% of the theoretical coulomb number required for the complete conversion of 5-hydroxymethylfurfural. This provides sufficient charge to ensure the reaction is as complete as possible.

[0039] In an embodiment of the present invention, the molar concentration of 5-hydroxymethylfurfural in the cathode electrolyte is 100 mM to 1000 mM.

[0040] In an embodiment of the present invention, the cathode electrolyte also contains 0.5M PBS with pH=7.

[0041] In the embodiments of the present invention, Ag / AgCl is used as the reference electrode and platinum is used as the counter electrode.

[0042] In an embodiment of the present invention, the anolyte is a 0.5M H2SO4 solution. Attached Figure Description

[0043] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0044] Figure 1 This is a transmission electron microscope (TEM) image of the PMA / Cu catalyst prepared in Example 1 of this invention.

[0045] Figure 2 This is a high-angle annular dark-field image (HAADF) of the PMA / Cu catalyst prepared in Example 1 of this invention and its elemental distribution diagram.

[0046] Figure 3 These are linear sweep voltammetric curves of the PMA / Cu catalyst prepared in Example 1 of this invention and the Cu catalyst prepared in Comparative Example 2.

[0047] Figure 4 This describes the Faradaic efficiency of the HMF hydrogenation products and the formation rate of BHMF of the PMA / Cu catalyst prepared in Example 1 of this invention at different potentials.

[0048] Figure 5 This invention relates to the Faraday efficiency of the HMF hydrogenation products and the formation rate of BHMF of the Cu catalyst prepared in Comparative Example 2 at different potentials.

[0049] Figure 6 This describes the Faradaic efficiency of the hydrogenation products and the BHMF formation rate of the PMA / Cu catalyst prepared in Example 1 of this invention under different HMF concentrations.

[0050] Figure 7 These are the linear sweep voltammetric curves of the PMA / Cu-2 catalyst prepared in Example 2 of this invention and the Cu catalyst prepared in Comparative Example 2.

[0051] Figure 8 These are the linear sweep voltammetric curves of the PMA / Cu-3 catalyst prepared in Example 3 of this invention and the Cu catalyst prepared in Comparative Example 2.

[0052] Figure 9 These are the linear sweep voltammetry curves of the PMA / Cu-4 catalyst prepared in Example 4 of this invention and the Cu catalyst prepared in Comparative Example 2.

[0053] Figure 10 These are the linear sweep voltammetric curves of the SWA / Cu catalyst prepared in Example 5 of this invention and the Cu catalyst prepared in Comparative Example 2.

[0054] Figure 11 This is a stability test of the PMA / Cu catalyst prepared in Example 1 of the present invention at a potential of -0.3V and a concentration of 0.25MHMF. Detailed Implementation

[0055] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0056] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0057] In this invention, "M" represents mol / L, "mM" represents mmol / L, and PBS represents phosphate buffered saline solution. The pH of the PBS buffer used in this invention is 7. Cu(OH)₂ nanowires, CuO nanowires, and Cu nanowires can be prepared according to relevant prior art. The Cu(OH)₂ nanowires, CuO nanowires, and Cu nanowires in this invention can be loaded onto copper foam, carbon paper, or activated carbon. Of course, they can also be used directly without a carrier, such as Cu(OH)₂ nanowires, CuO nanowires, and Cu nanowire powders. It is understood that this invention does not particularly limit the form in which Cu(OH)₂ nanowires, CuO nanowires, and Cu nanowires exist; any loaded or unloaded Cu(OH)₂ nanowires, CuO nanowires, and Cu nanowires are applicable to this invention.

[0058] Comparative Example 1

[0059] According to the method described in Example 1 of Chinese Patent Document CN113430559A, copper foam loaded with Cu nanowires was prepared, specifically as follows:

[0060] (1) Pre-treatment of 1cm×2cm foamed copper sheet: Sonicate the foamed copper in 3mol / L hydrochloric acid, acetone and deionized water for 10 minutes each, and then wash it with deionized water.

[0061] (2) The pretreated copper foam was used as both the cathode and anode in a 3 mol / L sodium hydroxide solution for electrochemical etching at a current density of 20 mA / cm². 2 Under certain conditions, current etching for 10 minutes yields Cu(OH)2 nanowires loaded on copper foam.

[0062] (3) Place Cu(OH)2 nanowires in a boat and calcine them in a muffle furnace. The temperature is increased to 300℃ at 1℃ / min and held for 2 hours to obtain CuO nanowires loaded on copper foam.

[0063] (4) In the H-type three-electrode electrolytic cell, the CuO nanowires loaded on copper foam obtained in step (3) are directly used as the working electrode, Ag / AgCl is used as the reference electrode, a platinum electrode is used as the counter electrode, a 0.5 mol / L Na2SO4 solution is used as the electrolyte in the anode chamber, and a solution containing 0.05 mol / L 5-hydroxymethylfurfural and 0.5 mol / L Na2SO4 is used as the electrolyte in the cathode chamber. The chambers are separated by a DuPont 117 cation exchange membrane. The Cu nanowires loaded on copper foam are obtained by electrochemical reduction at 0.4 V for 10 minutes, which is the Cu catalyst.

[0064] Comparative Example 2

[0065] This comparative example provides a method for preparing copper foam loaded with Cu(OH)₂ nanowires, copper foam loaded with CuO nanowires, and copper foam loaded with Cu nanowires, as detailed below:

[0066] Step 1: Cut the 1mm thick copper foam to 1x2cm, then ultrasonically wash it with 3mol / L hydrochloric acid, acetone, and deionized water respectively, and dry it in the air.

[0067] Step 2: Prepare a mixed aqueous solution with a concentration of 2.5 mol / L NaOH and 50 mmol / L (NH4)2S2O8.

[0068] Step 3: Immerse the copper foam obtained in Step 1 in the 3ml solution prepared in Step 2 for 20-30 minutes.

[0069] Step 4: Remove the copper foam with Cu(OH)2 nanowires grown on it, wash it with deionized water, and dry it in an oven at 80°C.

[0070] Step 5: The prepared Cu(OH)2 nanowires were calcined in a muffle furnace at a temperature of 250℃, a heating rate of 5℃ / min, and a calcination time of 2 hours to obtain copper foam loaded with CuO nanowires.

[0071] Step 6: The CuO nanowires obtained in Step 5 were used as the cathode for electrochemical reduction. The electrolytes for both the cathode and anode were 0.5M PBS solution with pH=7. The reduction potential was -0.4V, and the reduction time was 40 minutes. The reduced cathode was removed, rinsed with deionized water, and dried to obtain the Cu nanowire catalyst grown on copper foam.

[0072] Example 1

[0073] The preparation method of the PMA / Cu catalyst provided in this embodiment is as follows:

[0074] Step 1: Dissolve 4.4 mg of phosphomolybdic acid (PMA) in 3 ml of ethanol to prepare a 0.8 mmol / L PMA solution.

[0075] Step 2: Immerse the copper foam (1x2cm, prepared in the same way as Comparative Example 2 of this invention) loaded with CuO nanowires in the PMA solution prepared in step 1 for 30 min.

[0076] Step 3: Remove the soaked CuO nanowires and dry them in an oven at 80°C.

[0077] Step 4: Calcine the dried catalyst precursor under a nitrogen atmosphere at a temperature of 300℃, a heating rate of 2℃ / min, and a calcination time of 2 hours.

[0078] Step 5: Using an H-type electrolytic cell, the calcined catalyst precursor was used as the cathode for electrochemical reduction. Both the cathode and anolyte were 0.5M PBS solution with pH=7. The reduction potential was -0.3V, and the reduction time was 30 minutes. The reduced cathode was removed, rinsed with deionized water, and dried to obtain the PMA / Cu catalyst.

[0079] According to ICP-MS and SEM measurements, the mass ratio of PMA to Cu nanowires in the PMA / Cu catalyst prepared in this example is 1%, the length of Cu nanowires is 0.5-1 μm, and the width is about 100 nm.

[0080] like Figure 1 As shown, the PMA / Cu catalyst prepared in this embodiment exhibits a porous rod-like structure, which is due to structural shrinkage after CuO is electroreduced to Cu. From Figure 2 It can be seen that Cu, Mo and O elements are present in PMA / Cu, which indicates that the phosphomolybdic acid modifier was successfully loaded onto the Cu surface.

[0081] Example 2

[0082] The preparation method of the PMA / Cu-2 catalyst provided in this embodiment is as follows:

[0083] Step 1: Dissolve 5.5 mg of phosphomolybdic acid (PMA) in 3 ml of ethanol to prepare a 1 mmol / L PMA solution.

[0084] Step 2: Immerse the copper foam (1x2cm, prepared in the same way as Comparative Example 2 of this invention) loaded with Cu(OH)2 nanowires in the PMA solution prepared in step 1 for 60 min.

[0085] Step 3: Remove the soaked Cu(OH)2 nanowires and dry them in an oven at 60°C.

[0086] Step 4: Place the dried catalyst precursor in an argon atmosphere and calcine it at a temperature of 300℃, a heating rate of 3℃ / min, and a calcine time of 3 hours.

[0087] Step 5: Using an H-type electrolytic cell, the calcined catalyst precursor was used as the cathode for electrochemical reduction. Both the cathode and anolyte were 0.5M PBS solution with pH=7. The reduction potential was -0.4V, and the reduction time was 30 minutes. The reduced cathode was removed, rinsed with deionized water, and dried to obtain the PMA / Cu-2 catalyst.

[0088] SEM characterization showed that the length of Cu nanowires in the PMA / Cu-2 catalyst prepared in this example was 0.5–2 μm and the width was 100–200 nm.

[0089] Example 3

[0090] The preparation method of the PMA / Cu-3 catalyst provided in this embodiment is as follows:

[0091] Step 1: Dissolve 4.5 mg of sodium phosphomolybdate (NaPMA) in 3 ml of ethanol to prepare a 0.8 mmol / L NaPMA solution.

[0092] Step 2: Immerse the copper foam (1x2cm, prepared in the same way as Comparative Example 2 of this invention) loaded with CuO nanowires in the NaPMA solution prepared in Step 1 for 60 min.

[0093] Step 3: Remove the soaked CuO nanowires and dry them in an oven at 80°C.

[0094] Step 4: Calcine the dried catalyst precursor under a nitrogen atmosphere at a temperature of 300℃, a heating rate of 2℃ / min, and a calcination time of 2 hours.

[0095] Step 5: Using an H-type electrolytic cell, the calcined catalyst precursor was used as the cathode for electrochemical reduction. Both the cathode and anolyte were 0.5M PBS solution with pH=7. The reduction potential was -0.3V, and the reduction time was 30 minutes. The reduced cathode was removed, rinsed with deionized water, and dried to obtain the PMA / Cu catalyst.

[0096] SEM characterization showed that the Cu nanowires in the PMA / Cu-3 catalyst prepared in this example had a length of 0.5–1 μm and a width of about 100 nm.

[0097] Example 4

[0098] The method for preparing the PMA / Cu-4 catalyst provided in this embodiment is as follows:

[0099] Step 1: Place the copper foam loaded with Cu(OH)2 nanowires (preparation method is the same as Comparative Example 2 of this invention) in a hydrogen-argon mixed atmosphere (where the hydrogen volume concentration is 5v%) and calcine it. The heating rate is 1℃ / min, the calcine temperature is 300℃, and the calcine time is 3 hours to obtain the copper foam loaded with Cu nanowires.

[0100] Step 2: Dissolve 2.8 mg of phosphomolybdic acid (PMA) in 3 ml of ethanol to prepare a 0.5 mmol / L PMA solution.

[0101] Step 3: Immerse the copper foam (1x2cm) loaded with Cu nanowires obtained in Step 1 in the PMA solution prepared in Step 2 for 30 min.

[0102] Step 4: Remove the soaked Cu nanowires and dry them at room temperature.

[0103] Step 5: The dried catalyst precursor is calcined under a nitrogen atmosphere at a temperature of 200℃, a heating rate of 2℃ / min, and a calcination time of 3 hours to obtain the PMA / Cu-4 catalyst.

[0104] Example 5

[0105] The preparation method of the SWA / Cu catalyst provided in this embodiment is as follows:

[0106] Step 1: Dissolve 8.6 mg of silicotungstic acid (SWA) in 3 ml of methanol to prepare a 1.5 mmol / L SWA solution.

[0107] Step 2: Immerse the copper foam (1x2cm, prepared in the same way as Comparative Example 2 of this invention) loaded with CuO nanowires in the SWA solution prepared in step 1 for 2 hours.

[0108] Step 3: Remove the soaked CuO nanowires and dry them in an oven at 40°C.

[0109] Step 4: Calcine the dried catalyst precursor under a nitrogen atmosphere at a temperature of 200℃, a heating rate of 2℃ / min, and a calcination time of 2 hours.

[0110] Step 5: Using an H-type electrolytic cell, the calcined catalyst precursor was used as the cathode for electrochemical reduction. Both the cathode and anolyte were 0.5M PBS solution with pH=7. The reduction potential was -0.5V, and the reduction time was 20 minutes. The reduced cathode was removed, rinsed with deionized water, and dried to obtain the SWA / Cu catalyst.

[0111] According to SEM characterization, the Cu nanowires in the SWA / Cu catalyst prepared in this example have a length of 0.1-0.5 μm and a width of about 100 nm.

[0112] Example 6

[0113] Using a Metrohm Vionic electrochemical workstation and an H-type electrolytic cell, the PMA / Cu catalyst prepared in Example 1 of this invention or the Cu catalyst prepared in Comparative Example 2 was used as the cathode (electrode area 1 cm²). 2 Ag / AgCl was used as the reference electrode, and a platinum mesh as the counter electrode. The cathode electrolyte was 20 ml of 0.5 M PBS or 0.5 M PBS solution containing 0.1 M HMF. The anolyte was 0.5 M H₂SO₄ solution. The two electrolytes were separated by a Nafion 212 proton exchange membrane. Linear sweep voltammetry (LSV) was performed within a potential range of 0.05 to -0.5 V relative to the standard hydrogen electrode. Figure 3 The results are shown.

[0114] from Figure 3 It can be seen that the PMA / Cu catalyst at -100 mAcm -2 At a current density of -200 mA cm⁻¹, the overpotential for the hydrogen evolution reaction is only 225 mV, which is nearly 200 mV lower than that of the Cu catalyst. The PMA / Cu catalyst at -200 mA cm⁻¹ exhibits this effect. -2 The HMF hydrogenation current density only requires a potential of -0.273V, compared to -0.450V for Cu catalyst.

[0115] The electrochemical performance of the Cu catalyst prepared in Comparative Example 1 was tested using the same method as in this embodiment. The results showed that, compared with Comparative Example 1, the Cu catalyst in Comparative Example 2 had a lower overpotential required to reach the corresponding current (Comparative Example 1 reached -120 mA cm⁻¹). -2 The HMF hydrogenation current density required to be achieved was approximately -0.6V, while Comparative Example 2 reached -120mA / cm². -2 The hydrogenation current density of HMF requires the application of a potential of -0.4V.

[0116] Experimental Example 7

[0117] The method for preparing 2,5-furandiethanol by catalytic electrohydrogenation of 5-hydroxymethylfurfural provided in this embodiment is as follows:

[0118] An H-type electrolytic cell was selected, and the PMA / Cu catalyst prepared in Example 1 of this invention or the Cu catalyst prepared in Comparative Example 2 was used as the cathode (electrode area 1 cm²). 2 Ag / AgCl was used as the reference electrode, and a platinum mesh was used as the counter electrode. The cathode electrolyte was 20 ml of 0.5 M PBS solution containing 100 mmol HMF, and the anolyte was 0.5 M H2SO4 solution. The two electrolytes were separated by a Nafion 212 proton exchange membrane. An applied negative potential was used for the electrochemical hydrogenation reaction of HMF. After 150 coulombs, the reaction products were analyzed by high-performance liquid chromatography (HPLC). The results are shown in Tables 1-2 and 2-3. Figure 4-5 As shown.

[0119] Table 1. Conversion and selectivity of PMA / Cu catalysts after reacting at different reaction potentials for 150 coulombs.

[0120]

[0121]

[0122] Table 2. Conversion and selectivity of Cu catalyst after reaction at different reaction potentials for 150 coulombs.

[0123]

[0124] As shown in Table 1-2, the PMA / Cu catalyst maintains extremely high selectivity for BHMF as the potential increases, but the selectivity of the Cu catalyst for BHMF decreases significantly as the potential increases. This indicates that the Cu catalyst modified by PMA (i.e., the PMA / Cu catalyst) has higher selectivity for BHMF.

[0125] from Figure 4 It can be seen that within the corresponding potential range, the main conversion product of the hydrogenation reaction of HMF by the PMA / Cu catalyst is BHMF, with a hydrogen evolution Faraday efficiency of only about 15%. Moreover, only a very small amount of coupling byproduct BHH is generated at relatively negative potentials, while the formation rate of BHMF is as high as 5.5 mmol / cm² at a potential of -0.4 V. -2 h -1 This demonstrates that Cu-supported PMA modifier (i.e., PMA / Cu catalyst) exhibits excellent selectivity and extremely high catalytic activity in the hydrogenation preparation of BHMF.

[0126] from Figure 5 It can be seen that although the reaction rate of Cu catalyst gradually increases with increasing potential, the reaction rate is much lower than that of PMA / Cu catalyst. Moreover, the hydrogenation byproducts of HMF (especially the coupling product BHH) increase significantly, and the selectivity of BHMF decreases. This indicates that Cu catalyst has low Faraday efficiency for BHMF.

[0127] Example 8

[0128] The method for preparing 2,5-furandiethanol by catalytic electrohydrogenation of 5-hydroxymethylfurfural provided in this embodiment is as follows:

[0129] An H-type electrolytic cell was selected, and the PMA / Cu catalyst prepared in Example 1 of this invention was used as the cathode (electrode area 1 cm²). 2 Ag / AgCl was used as the reference electrode, and a platinum mesh as the counter electrode. The cathode electrolyte was 20 ml of 0.5 M PBS solution containing dissolved HMF, and the anolyte was 0.5 M H2SO4 solution, separated by a Nafion 212 proton exchange membrane. An electrochemical hydrogenation reaction of HMF was performed with a negative potential of -0.3 V compared to the reversible hydrogen electrode. The coulomb number of the reaction was set to 101% of the theoretical coulomb number required for complete HMF conversion. After the reaction reached a specific coulomb number, the reaction products were analyzed by high-performance liquid chromatography (HPLC). The results are shown in Table 3. Figure 6 As shown.

[0130] Table 3. Conversion and selectivity of PMA / Cu catalysts after reacting with specific charge amounts at different HMF concentrations.

[0131]

[0132] As shown in Table 3, at a voltage of -0.3V (vs RHE), the PMA / Cu catalyst can still maintain a high HMF conversion rate and BHMF selectivity at a high concentration of 1M HMF.

[0133] from Figure 6 It can be seen that the Faradaic efficiency of the PMA / Cu catalyst for BHMF further increases with increasing HMF concentration, and the Faradaic efficiency of the hydrogen evolution reaction is suppressed. Moreover, even at an HMF concentration of 1M, the Faradaic efficiency of the coupling byproduct BHH is as low as 2.5%. This indicates that the PMA / Cu catalyst has extremely high tolerance to HMF concentration for the hydrogenation selectivity of BHMF.

[0134] The PMA / Cu-2, PMA / Cu-3, PMA / Cu-4, and SWA / Cu catalysts prepared using Examples 2-5 of this invention also exhibited essentially the same reaction patterns and effects as those in Example 6 (see Example 6). Figure 7-10 Therefore, I will not elaborate further here.

[0135] Example 9

[0136] The stability of the PMA / Cu catalyst prepared in Example 1 of this invention was tested for the electrocatalytic hydrogenation of HMF to BHMF. The test results are as follows: Figure 11 As shown. The test method was as follows: A Metrohm Vionic electrochemical workstation was used, with an H-type electrolytic cell. The test was conducted in a three-electrode system using Ag / AgCl as the reference electrode, a platinum mesh as the counter electrode, and PMA / Cu as the working electrode. The cathode electrolyte was a 0.25M HMF solution in 0.5M PBS. 250ml or 500ml of cathode electrolyte was prepared for each cycle. The electrolyte in the storage bottle was pumped into the electrolytic cell using a peristaltic pump, and the electrolyte was removed from the cell after the reaction, ensuring that the electrolyte volume in the cell remained at 20ml. The electrochemical hydrogenation stability of HMF was tested by applying a voltage of -0.3V relative to the standard hydrogen electrode to the cathode catalyst. The coulomb number of the reaction was set to 101% of the theoretical coulomb number required for complete HMF conversion. The total volume of the cathode electrolyte in the first three cycles was 250ml, and the total volume of the electrolyte in the last two cycles was 500ml. Electrolysis is paused for 2 minutes every 58 minutes. During the pause, the peristaltic pump maintains liquid circulation to ensure that the HMF concentration in the reaction tank is consistent with that in the storage bottle. Once the electrolyte in a single storage bottle has reached 101% of the theoretical coulomb number, the cathode electrolyte is replaced with fresh electrolyte.

[0137] The results show that the PMA / Cu catalyst prepared in this invention can maintain good stability within a time range of 80 hours.

[0138] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A process for preparing 2,5-furandiethanol, characterized in that, Includes the following steps: Using a catalyst as the cathode, the cathode is placed in a cathode electrolyte containing dissolved 5-hydroxymethylfurfural, and an electrochemical hydrogenation reaction is carried out by applying a negative voltage; The molar concentration of 5-hydroxymethylfurfural in the cathode electrolyte is 100 mM to 1000 mM; The catalyst comprises: Cu nanowires and a modifier supported on the Cu nanowires, wherein the modifier is a Keggin-type heteropolyacid and / or heteropolyacid salt; The Keggin-type heteropolyacid is at least one of phosphomolybdic acid, silicotungstic acid, and phosphotungstic acid. The Keggin-type heteropolyacid salt is at least one of sodium phosphomolybdate and ammonium phosphotungstate.

2. The process for preparing 2,5-furandiethanol according to claim 1, characterized in that, The mass ratio of the modifier to the Cu nanowires is 0.1% to 10%. And / or, the Cu nanowires have a length of 0.5~12μm and a width of 50~200nm.

3. The process for preparing 2,5-furandiethanol according to claim 2, characterized in that, The mass ratio of the modifier to the Cu nanowires is 0.5% to 2%.

4. The process for preparing 2,5-furandiethanol according to claim 1, characterized in that, The method for preparing the catalyst includes the following steps: S1. Dissolve the modifier in an alcohol solvent to form a modifier solution, wherein the modifier is a Keggin-type heteropolyacid and / or heteropolyacid salt; S2. Place CuO nanowires and / or Cu(OH)2 nanowires in the modifier solution, soak for a first time, remove, dry, and calcine in the presence of protective gas or air to obtain the precursor. or Cu nanowires were immersed in the modifier solution for a first time, then removed, dried, and calcined in the presence of a protective gas or air to obtain a catalyst. S3. The precursor is used as a cathode for electrochemical reduction. The reduced cathode is removed, cleaned, and dried to obtain the catalyst.

5. The process for preparing 2,5-furandiethanol according to claim 4, characterized in that, The concentration of the modifier solution is 0.3 mmol / L to 2 mmol / L; And / or, the alcohol solvent is at least one of methanol, ethanol, and isopropanol.

6. The process for preparing 2,5-furandiethanol according to claim 4, characterized in that, The first time period is 20 minutes to 4 hours; And / or, the drying temperature in step S2 is 25°C to 80°C; And / or, the calcination temperature is 200℃~350℃, the heating rate is 1~5℃ / min, and the time is 1h~5h; And / or, the protective gas is at least one of nitrogen and argon.

7. The process for preparing 2,5-furandiethanol according to claim 6, characterized in that, The first time period is 30 minutes to 1 hour.

8. The process for preparing 2,5-furandiethanol according to claim 4, characterized in that, In step S3, the reduction potential is -0.2V to -0.7V, and the reduction time is 20min to 1h. And / or, in step S3, Ag / AgCl is used as the reference electrode, a platinum electrode is used as the counter electrode, and the electrolytes for both the cathode and anolyte are 0.5M PBS solutions with pH=7.

9. The process for preparing 2,5-furandiethanol according to claim 1, characterized in that, The cathode has an electrode area of ​​1 cm². 2 ; And / or, the negative voltage is -0.15V to -0.4V; And / or, the coulomb number of the electrochemical hydrogenation reaction is 101% of the theoretical coulomb number required for the complete conversion of 5-hydroxymethylfurfural.

10. The process for preparing 2,5-furandiethanol according to claim 1, characterized in that, The cathode electrolyte also contains 0.5M PBS with pH=7; And / or, using Ag / AgCl as the reference electrode and platinum as the counter electrode; And / or, the anolyte is a 0.5M H2SO4 solution.

Images