Preparation method and application of catalyst for electrocatalytic conversion of HMF into FDCA

Abstract

The invention discloses a preparation method of a catalyst for electrocatalytic conversion of HMF into FDCA. The catalyst is used in the process of efficient electrocatalytic conversion of biomass micromolecule 5-hydroxymethylfurfural (HMF) into FDCA. The preparation method comprises the following steps: firstly, preparing an amorphous mixed metal substrate through electro-deposition, then synthesizing CuNiO and grafting a PO4 inorganic ligand in situ through electrochemistry, and finally preparing the final PO4 / CuNiOOH through electrochemical activation. According to the catalyst PO4 / CuNiOOH disclosed by the invention, not only can the Faraday efficiency, the HMF conversion rate and the product selectivity of electrocatalytic conversion of HMF into FDCA be obviously improved, but also the current density in the reaction process can be obviously improved and exceeds the industrial-grade current density requirement (200mA cm <-2 >), and the electrode stability is also obviously improved. The preparation process is simple and easy to operate, the electrode is convenient to use, and the method is suitable for industrial production and market popularization and application.

Description

Technical Field

[0001] The present application relates to the field of catalyst upgrading and conversion, and specifically to a preparation method and application of a catalyst for electrocatalytic conversion of HMF into FDCA. Background Art

[0002] Bio-based 2,5-furandicarboxylic acid (FDCA), which is converted from biomass small molecules, has a unique furan ring molecular structure, is 100% biodegradable, and is excellent in environmental friendliness. Compared with conventional plastic polyesters, it has greatly improved key properties such as toughness and strength. Therefore, FDCA has received high attention in strategic emerging fields such as new energy battery separators and high-performance polyesters, and has extremely broad market prospects. The traditional thermal catalytic synthesis route of FDCA usually requires high temperature and high pressure, external oxidants and organic solvents, and has many by-products and is prone to secondary pollution. In response to this, the electrocatalytic bio-based small molecule 5-hydroxymethylfurfural (HMF) technology route has received widespread attention at home and abroad. The electrocatalytic reaction conditions are mild, which can effectively avoid excessive energy loss during the reaction process. At the same time, electro-oxidation can effectively avoid the use of chemical oxidants, further reducing the reaction cost.

[0003] In recent years, relevant studies have shown that among many catalysts, nickel-based catalysts have great adaptability in the field of HMF electrocatalytic conversion because of their rich three-dimensional electron numbers and unique electron orbits that can enhance the covalency of transition metal-oxygen bonds, catalyst surface reconstruction, and compliance with the "electrochemical-chemical" reaction pathway. However, most researchers have focused on the Faraday efficiency of FDCA, while ignoring the current density of HMF conversion at high Faraday current efficiency. In fact, in existing studies, the current density of HMF conversion at high Faraday current efficiency is generally lower than 200 mA cm -2 This low current density makes it impossible to achieve industrial-grade high current density (>200mAcm) under alkaline conditions. -2 ) for the production of FDCA, thus limiting the application of this technology in large-scale industrial production. Therefore, how to construct abundant active sites on the basis of nickel-based catalysts to improve the current density of HMF conversion has become the focus and hot issue of current research in this field. Cu doping has been shown to be an effective way to inhibit the competitive reaction OER reaction in the HMF electrocatalytic process, but whether it can promote the current density of the electrocatalytic reaction has not been reported. In addition, inorganic functional groups on the metal surface (PO 4 3- 、SO 4 2- , HPO 4 2-The research on changing the microenvironment of the system has been reported in various fields such as water electrolysis, oxygen evolution, and hydrogen evolution, indicating that inorganic functional groups on the metal surface can greatly promote electrochemical conversion, proton transfer and other processes. Related studies have shown that inorganic functional groups on the metal surface can change the electrolyte OH in the system. - Ionic interactions indirectly affect the selectivity and stability of catalysts. However, in the field of HMFOR, there is a lack of systematic research on inorganic functional groups on metal surfaces. Summary of the invention

[0004] In order to solve the problems in the prior art, the present application provides a method for preparing a catalyst for electrocatalytic conversion of HMF into FDCA, the preparation method comprising the following steps:

[0005] Step 1, preparing an amorphous mixed metal substrate by electrodeposition, wherein the electrodeposition electrolyte comprises a mixed solution of divalent nickel ions, divalent copper ions and sodium citrate, wherein the concentration ratio of nickel ions to copper ions is 0.1-5, and the electrodeposition is carried out in a multi-electrode system with constant current loading to prepare an amorphous mixed metal substrate;

[0006] Step 2: In situ preparation of catalyst precursor PO by electrochemical 4 / CuNiO, wherein the electrochemical in-situ synthesis is to prepare the amorphous mixed metal substrate by hydrothermal soaking in a hydrothermal soaking solution in step 1, and then rinse and dry after the soaking to obtain the catalyst precursor PO 4 / CuNiO;

[0007] Step 3: Preparation of the catalyst inorganic ligand PO for electrocatalytic conversion of HMF to FDCA by electrochemical activation 4 / CuNiOOH, the catalyst precursor PO prepared in step 2 4 / CuNiO is electrochemically activated, and the electrochemical activation is CV scanning under a three-electrode system. After the scanning, a catalyst for electrocatalytic conversion of HMF into FDCA is obtained.

[0008] The present application also provides a catalyst prepared according to the preparation method for electrocatalytic conversion of HMF into FDCA.

[0009] The present application provides the use of a prepared catalyst for electrocatalytic conversion of HMF into FDCA in an electrocatalytic system for electrocatalytic conversion of biomass small molecule HMF in an alkaline solution into FDCA.

[0010] Beneficial Effects

[0011] The PO prepared by the present invention 4The / CuNiOOH catalyst can improve the Faradaic efficiency of HMF electrocatalytic conversion to FDCA while also increasing the current density to an industrial-grade current density level.

[0012] In view of the problems existing in the prior art, the present invention proposes a PO with high current density. 4 / CuNiOOH catalyst was prepared and applied to the electrocatalytic conversion of biomass small molecule HMF into FDCA under alkaline conditions. 4 The CuNiOOH catalyst can not only easily achieve efficient conversion of HMF and high Faradaic efficiency of FDCA, but also increase the current density to more than 200 mA cm -2 .PO 4 / CuNiOOH first prepares the amorphous metal substrate CuNiO by electrodeposition, and applies a stable negative voltage to the electrode substrate to reduce the divalent nickel ions and divalent copper ions in the electrolyte on the substrate. In the mixed solution, the standard reduction potential of divalent copper is much lower than that of divalent nickel, so it is easier to be reduced on the electrode substrate first. In order to achieve the simultaneous electrodeposition of copper and nickel, sodium citrate is added to the electrolyte as a coupling agent, which can simultaneously anchor the divalent copper and nickel ions in the solution, reduce the potential difference between the two, and achieve the joint deposition of copper and nickel. The CuNiO obtained after the electrodeposition is electrochemically phosphated, and the CuNiO is placed in an ultrasonic Ni-containing 2+ ,NO3 2- ,HPO 4 2- The mixed solution is further hydrothermally treated. 4 2 - further ionized to generate PO 4 3- and weak acid environment, while the solution has NO 3 2- It has certain oxidizing properties in a weak acid environment and can convert Ni formed on the surface of the catalyst during electrodeposition 2+ and Cu 2+ Released to the solid-liquid interface layer with the solution. In the solid-liquid interface layer, the metal activity of nickel is before that of copper. Nickel can replace copper ions from the solid-liquid interface layer, and the reaction Ni+Cu 2+ =Ni 2+ +Cu reaction. In addition, PO4 3- Further with Ni in solution 2+ and Cu 2+ The reaction generates Ni 3 (PO 4 ) 2 and Cu 3 (PO 4 ) 2 , Ni3 (PO 4 ) 2 and Cu 3 (PO 4 ) 2 Anchored to the catalyst surface to obtain PO 4 / CuNiO. Finally, PO 4 / CuNiO was electrochemically activated under alkaline conditions to form PO 4 / CuNiOOH and used for HMF electrocatalytic conversion.

[0013] There are usually two pathways for HMF to be converted into FDCA under alkaline electrolyte conditions: the CHO or OH group on the furan ring of HMF is oxidized to form the corresponding intermediate (5-hydroxymethyl 2-furancarboxylic acid (HMFCA) or 2,5-diformylfuran (DFF)), and then these two pathways are combined on another intermediate 2-formyl-5-furancarboxylic acid (FFCA), which is finally further oxidized to FDCA. The entire reaction process requires the transfer of 6 electrons and is completed on the electrode surface. The inorganic ligand PO generated in situ on the electrode surface 4 / CuNiOOH is the main active site of the reaction, promoting the deprotonation and dehydrogenation of HMF and intermediate products and the coupled transfer of electrons on the electrode surface, and is the main active site of the reaction. The higher the activity of the active site, the higher the reaction efficiency.

[0014] This application PO 4 Inorganic ligand PO in CuNiOOH 4 It can stabilize the acidity and alkalinity in the microenvironment of the electrode surface, prolong the service life of the catalyst, and significantly improve the stability of the electrocatalytic conversion of HMF to FDCA;

[0015] The PO prepared in this application 4 The Cu / CuNiO catalyst has good HMF electrooxidation activity, with an initial potential lower than 1.37 V vs RHE and a current density greater than 200 mA cm -2 , exceeding the industrial-grade current density requirements. In the wide range of 1.45-1.6V, the conversion rates of FE and HMF of FDCA can reach more than 95%. Compared with the catalysts reported so far, PO4 / CuNiOOH has obvious advantages in electrocatalytic performance and FDCA conversion. 4 The cyclic performance of the CuNiOOH catalyst far exceeds that reported. In a 10 ml 10 mM HMF solution system, after more than 15 cycles, the Faradaic efficiency of FDCA can still be maintained above 90%, and the carbon balance can be maintained above 95%.

[0016] The invention has simple preparation process, is easy to operate, and the electrode is convenient to use, and is suitable for industrial production and market promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 For PO 4 Schematic diagram of the preparation process of CuNiOOH catalyst

[0018] Figure 2 Schematic diagram of the mechanism of electrocatalytic conversion of HMF to FDCA;

[0019] Figure 3 PO prepared under the conditions of Example 1 of this application 4 / CuNiOOH for HMF electrocatalytic conversion performance diagram, including (a) LSV curve in 1M KOH and 50mM HMF solution, (b) Faraday efficiency of HMF conversion to FDCA at different voltages, (c) HMF conversion rate of HMF conversion to FDCA at different voltages, (d) number of catalyst cycles in 10mL of 10mM HMF;

[0020] Figure 4 PO prepared under the conditions of Example 2 of this application 4 / CuNiOOH for HMF electrocatalytic conversion performance diagram, including (a) LSV curve in 1M KOH and 50mM HMF solution, (b) Faraday efficiency of HMF conversion to FDCA at different voltages, (c) HMF conversion rate of HMF conversion to FDCA at different voltages, (d) number of catalyst cycles in 10mL of 10mM HMF;

[0021] Figure 5 PO prepared under the conditions of Example 3 of this application 4 / CuNiOOH for HMF electrocatalytic conversion performance diagram, including (a) LSV curve in 1M KOH and 50mM HMF solution, (b) Faraday efficiency of HMF conversion to FDCA at different voltages, (c) HMF conversion rate of HMF conversion to FDCA at different voltages, (d) number of catalyst cycles in 10mL of 10mM HMF;

[0022] Figure 6 PO prepared under Example 4 of this application 4 / CuNiOOH electrocatalytic conversion performance of HMF, including (a) LSV curve in 1M KOH and 50mM HMF solution, (b) Faraday efficiency of HMF conversion to FDCA at different voltages, (c) HMF conversion rate of HMF conversion to FDCA at different voltages, (d) number of catalyst cycles in 10mL of 10mM HMF DETAILED DESCRIPTION

[0023] The preferred embodiments of the present invention will be described in detail below in conjunction with examples. It should be understood that the following examples are provided only for the purpose of illustration and are not intended to limit the scope of the present invention. Those skilled in the art may make various modifications and substitutions to the present invention without departing from the purpose and spirit of the present invention.

[0024] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0025] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0026] An embodiment of the present application provides a method for preparing a catalyst for electrocatalytically converting HMF into FDCA, the preparation method comprising the following steps:

[0027] Step 1, preparing an amorphous mixed metal substrate by electrodeposition, wherein the electrodeposition electrolyte comprises a mixed solution of divalent nickel ions, divalent copper ions and sodium citrate, wherein the concentration ratio of nickel ions to copper ions is 0.1-5, and the electrodeposition is carried out in a multi-electrode system with constant current loading to prepare an amorphous mixed metal substrate;

[0028] Step 2: In situ preparation of catalyst precursor PO by electrochemical 4 / CuNiO, wherein the electrochemical in-situ synthesis is to prepare the amorphous mixed metal substrate by hydrothermal soaking in a hydrothermal soaking solution in step 1, and then rinse and dry after the soaking to obtain the catalyst precursor PO 4 / CuNiO;

[0029] Step 3: Preparation of the catalyst inorganic ligand PO for electrocatalytic conversion of HMF to FDCA by electrochemical activation 4 / CuNiOOH, the catalyst precursor PO prepared in step 2 4 / CuNiO is electrochemically activated, and the electrochemical activation is CV scanning under a three-electrode system. After the scanning, a catalyst for electrocatalytic conversion of HMF into FDCA is obtained.

[0030] In one embodiment, in step 1, the concentration ratio of nickel ions to copper ions is 0.6-4.

[0031] In one embodiment, the multi-electrode system includes a two-electrode system and a three-electrode system, wherein the working electrode is carbon fiber or foam metal, and the counter electrode is one of inert electrodes such as platinum sheet, graphite sheet, carbon paper, etc.; the reference electrode in the three-electrode system is one of Ag / AgCl, saturated calomel, and Hg / HgO.

[0032] In one embodiment, the metal foam includes nickel foam.

[0033] In one embodiment, the carbon fiber includes carbon cloth and carbon felt.

[0034] In one embodiment, in step 1, the electrodeposition electrolyte includes a mixed solution of divalent nickel ions, divalent copper ions and sodium citrate, the nickel ion concentration is 10mmol / L-100mmol / L, the copper ion concentration is 10mmol / L-100mmol / L, and the sodium citrate concentration is 1mmol / L-50mmol / L.

[0035] In one embodiment, in step 1, the electrodeposition electrolyte includes a mixed solution of divalent nickel ions, divalent copper ions and sodium citrate, the nickel ion concentration is 40mmol / L-80mmol / L, the copper ion concentration is 20mmol / L-60mmol / L, and the sodium citrate concentration is 5mmol / L-50mmol / L.

[0036] In one embodiment, in step 1, the use of constant current for loading is to use a constant current electrodeposition method for loading during the electrodeposition process, and the current density is -10mA / cm 2 To -120mA / cm 2 The electrodeposition time is 5 min to 30 min. The deposited working electrode is rinsed with deionized water and then vacuum dried at 60 °C to obtain an amorphous mixed metal substrate.

[0037] In one embodiment, in step 1, the use of constant current for loading is to use a constant current electrodeposition method for loading during the electrodeposition process, and the current density is -50 mA / cm 2 To -100mA / cm 2 .

[0038] In one embodiment, in step 2, the hydrothermal soaking liquid is Ni(NO 3 ) 2 6H 2 O, Cu(NO 3 ) 2 6H 2 O and Na 2 HPO 4 , NaNO 3 The prepared solution is ultrasonically dispersed, and then soaked. The hydrothermal soaking temperature is 40°C-100°C, and the hydrothermal soaking time is 30min-12h. After the soaking, it is rinsed with deionized water and vacuum dried at 60°C to obtain the catalyst precursor PO 4 / CuNiO.

[0039] In one embodiment, in step 2, the hydrothermal soaking temperature is 40°C-80°C.

[0040] In one embodiment, the Ni(NO 3 ) 2 6H 2 O and NaNO 3 The concentration is 20mmol / L-50mmol / L, Na 2 HPO 4 The concentration is 50mmol / L-100mmol / L.

[0041] In one embodiment, in a three-electrode system, PO 4 / CuNiO is the working electrode, the counter electrode is one of the inert electrodes such as platinum sheet, graphite sheet, carbon paper, etc., and the reference electrode is Hg / HgO.

[0042] In one embodiment, the CV scan is performed under a three-electrode system, the electrolyte is a 0.1 mol / L-2 mol / L KOH aqueous solution, the scanning range is 0.3 V vs RHE-1.6 V vs RHE, the scanning speed is 5-100 mV / sec, the scanning number is 10-50 circles, and PO is obtained after the scanning. 4 / CuNiOOH.

[0043] An embodiment of the present application provides a catalyst prepared by the preparation method for electrocatalytic conversion of HMF into FDCA.

[0044] One embodiment of the present application provides the use of a prepared catalyst for electrocatalytic conversion of HMF into FDCA in an electrocatalytic system for electrocatalytic conversion of biomass small molecule HMF in an alkaline solution into FDCA.

[0045] One embodiment of the present application provides a method for preparing a catalyst for electrocatalytic conversion of HMF into FDCA. The flow chart of the preparation method is shown in Figure 1 , the method comprises the following steps:

[0046] (1)PO 4 The CuNiO / CuNiOOH catalyst was first prepared by electrodeposition of an amorphous metal substrate CuNiO, and then PO was converted into 4 3- Grafted onto the CuNiO surface. Finally, PO was generated in situ by electrochemical activation. 4 / CuNiOOH.

[0047] (2) The electrodeposition process can be carried out in a two-electrode system or a three-electrode system, with nickel foam as the working electrode, the counter electrode being one of the inert electrodes such as platinum sheet, graphite sheet, carbon paper, etc., and the reference electrode in the three-electrode system being one of the electrodes such as Ag / AgCl, saturated calomel, and Hg / HgO.

[0048] (3) During the electrodeposition process, the electrolyte composition is a mixed solution of divalent nickel ions, divalent copper ions, and sodium citrate. Nickel ions can be NiCl 2 6H 2 O.Ni(NO 3 ) 2 6H 2 O、NiSO 4 6H 2 O and other salts containing divalent nickel, with a concentration in the range of 10-100mmol / L. Copper ions can be obtained from CuCl 2 ·2H 2 O, Cu(NO 3 ) 2 6H 2 O、CuSO 4 ·5H 2 O or one of the salts containing divalent copper, the concentration is in the range of 10-100mmol / L, the concentration ratio of nickel ion to copper ion is in the range of 0.1-1, and the concentration of sodium citrate is in the range of 1-50mmol / L;

[0049] (4) During the electrodeposition process, constant current electrodeposition is used for loading, with a current density of -10 to -120 mA / cm 2 The electrodeposition time is 5-30 min, and the deposited working electrode is rinsed with deionized water and then vacuum dried at 60° C. to obtain an amorphous mixed metal substrate;

[0050] (5) Surface grafting of PO 4 The method is hydrothermal soaking, and the composition of the hydrothermal soaking liquid is Ni(NO 3 ) 2 6H 2 O, Cu(NO 3 ) 2 6H 2 O,Na 2 HPO 4 , NaNO 3 Mixed solution, Ni(NO 3 ) 2 6H 2 O and NaNO 3 The concentration of Na 2 HPO 4The concentration of the catalyst is in the range of 50-100mmol / L. The prepared solution is ultrasonically dispersed and then soaked at a temperature of 60℃-100℃ for 30min-12h. After the soaking, it is rinsed with deionized water and vacuum dried at 60℃ to obtain a catalyst precursor PO 4 / CuNiO;

[0051] (6) Prepare the catalyst precursor PO 4 / CuNiO was electrochemically activated. The activation process was a three-electrode system. 4 / CuNiO is the working electrode, the counter electrode is one of the inert electrodes such as platinum sheet, graphite sheet, carbon paper, etc., the reference electrode is Hg / HgO, and the electrolyte is 0.1mol / L-2mol / L KOH aqueous solution. CV scanning is performed under this system with a scanning range of 0.3V vsRHE-1.6V vs RHE, a scanning speed of 5-100mV / sec, and a scanning number of 10-50 circles. After the scanning, PO is obtained. 4 / CuNiOOH;

[0052] (7) The obtained PO 4 / CuNiOOH is used in the electrocatalytic system to efficiently and high current density convert the biomass small molecule HMF into FDCA in alkaline solution.

[0053] Embodiment 1:

[0054] Preparation of catalysts with different electrodeposition ratios:

[0055] A method for preparing and applying an efficient catalyst for electrocatalyzing 5-hydroxymethylfurfural (HMF) to furandicarboxylic acid (FDCA) at a high current density under alkaline conditions is as follows:

[0056] (1)PO 4 / Electrodeposition process of CuNiOOH catalyst preparation:

[0057] The electrodeposition process was carried out in a three-electrode system, with nickel foam as the working electrode, platinum sheet as the counter electrode, and Hg / HgO as the reference electrode.

[0058] The electrolyte composition during electrodeposition is NiCl 2 6H 2 O, Cu(NO 3 ) 2 6H 2 O and C 6 H 5 Na 3 O 7 ·3H 2 A mixed solution of O, NiCl2 6H 2 O concentration and Cu(NO 3 ) 2 6H 2 O concentrations were 40mmol / L+60mmol / L, 50mmol / L+50mmol / L, 80mmol / L+20mmol / L, C 6 H 5 Na 3 O 7 ·3H 2 The O concentration was 20 mmol / L, and the volume of the electrodeposition solution was 30 mL.

[0059] The loading was performed by constant current electrodeposition with a current density of -50 mA / cm 2 The electrodeposition time was 10 min. After deposition, the three working electrodes were rinsed with deionized water and then vacuum dried at 60 °C to obtain three amorphous mixed metal substrates, which were respectively recorded as substrate 1, substrate 2, and substrate 3.

[0060] (2)PO 4 Phosphorylation hydrothermal soaking process of CuNiOOH preparation:

[0061] The hydrothermal soaking solution is composed of Ni(NO 3 ) 2 6H 2 O,Na 2 HPO 4 , NaNO 3 The mixed solution was ultrasonicated for 30 min, and Ni(NO 3 ) 2 6H 2 O and NaNO 3 The concentration of Na 2 HPO 4 The concentration of 50mmol / L, the immersion temperature of 80℃, and the immersion time of 30min were all immersed in the hydrothermal phosphoric acid solution. After the immersion, the substrates were rinsed with deionized water and then vacuum dried at 60℃ to obtain three catalyst precursors PO 4 / CuNiO.

[0062] (3)PO 4 Electrochemical activation of self-loading NiOOH prepared by CuNiOOH:

[0063] The electrochemical activation of NiOOH was completed in a three-electrode system. 4 / CuNiO was used as the working electrode, the counter electrode was platinum, the reference electrode was Hg / HgO, and the electrolyte was 1 mol / L KOH aqueous solution. CV scanning was performed in this system with a scanning range of 0.3V vs RHE-1.6V vs RHE, a scanning speed of 50mV / sec, and a scanning number of 20 circles. After the scanning, PO prepared under different electrodeposition ratios was obtained. 4 / CuNiOOH.

[0064] (4) PO produced 4 / Application of CuNiOOH in electrocatalytic conversion of biomass small molecule HMF to FDCA in alkaline solution:

[0065] The HMF electrocatalytic conversion experiment was carried out in an H-type reactor. The three-electrode system was set up as follows: the three prepared PO 4 / CuNiOOH was used as the working electrode, the counter electrode was platinum, the reference electrode was Hg / HgO, the electrolyte of the anode electrolytic cell was a mixed solution of 1 mol / L KOH and 50 mmol / L HMF, and the electrolyte of the cathode electrolytic cell was 1 mol / L KOH, separated by an anion exchange membrane Fuma-FAA-3-50.

[0066] The HMF electrocatalytic conversion performance test was carried out on the CHI660E electrochemical workstation. The LSV test was first performed and the results are shown in Figure 3 In (a), it can be seen that compared with the nickel foam without any catalyst, the starting potentials of the catalysts prepared in the three different electrodeposition solutions are all lower than 1.37 V vs RHE, and the current density is much higher than 200 mA cm -2 The electrocatalytic conversion performance of the catalyst for HMF was verified in the IT test, and the product was detected by HPLC. The Faradaic efficiency results of FDCA are shown in Figure 3 The results of HMF conversion are shown in (b) Figure 3 Middle (c): Within a wide range of 1.45-1.6 V, the conversion rates of FE and HMF of FDCA can reach more than 95%.

[0067] In addition, a cycle test was carried out in a 10 ml 10 mM HMF solution system. The cycle number results are shown in Figure 3 (d) The number of cycles of catalysts with different ratios is more than 15, and the Faraday efficiency of FDCA can still be maintained above 90% after the cycle. This shows that the catalysts prepared with different electrodeposition liquid ratios have a higher PO efficiency than those prepared with different electroplating liquid ratios. 4 / CuNiOOH not only has a high current density, but also can significantly improve the Faradaic efficiency, HMF conversion rate, and electrode stability of the electrocatalytic HMF to FDCA conversion.

[0068] Embodiment 2:

[0069] Preparation of catalysts with different electrodeposition current densities:

[0070] A method for preparing and applying an efficient catalyst for electrocatalyzing 5-hydroxymethylfurfural (HMF) to furandicarboxylic acid (FDCA) at a high current density under alkaline conditions is as follows:

[0071] (1)PO 4 / Electrodeposition process of CuNiOOH catalyst preparation:

[0072] The electrodeposition process was carried out in a three-electrode system, with nickel foam as the working electrode, platinum sheet as the counter electrode, and Hg / HgO as the reference electrode. The electrolyte composition during the electrodeposition process was NiCl 2 6H 2 O, Cu(NO 3 ) 2 6H 2 O and C 6 H 5 Na 3 O 7 ·3H 2 A mixed solution of O, NiCl 2 6H 2 O concentration was 40mmol / L, Cu(NO 3 ) 2 6H 2 O concentration is 60mmol / L, C 6 H 5 Na 3 O 7 ·3H 2 The O concentration was 5mmol / L, and the volume of the electrodeposition solution was 30mL. The constant current electrodeposition method was used for loading, and the current density was -50mA / cm 2 and -100mA / cm 2 The electrodeposition time was 10 min. After deposition, the two working electrodes were rinsed with deionized water and then vacuum dried at 60 °C to obtain two amorphous mixed metal substrates.

[0073] (2)PO 4 Phosphorylation hydrothermal soaking process of CuNiOOH preparation:

[0074] The hydrothermal soaking solution is composed of Ni(NO 3 ) 2 6H 2 O,Na 2 HPO 4 , NaNO 3 The mixed solution was ultrasonicated for 30 min, and Ni(NO 3 )2 6H 2 O and NaNO 3 The concentration of Na 2 HPO 4 The concentration of PO was 70mmol / L, the immersion temperature was 80℃, and the immersion time was 30min. Both substrates were immersed in the hydrothermal phosphoric acid solution. After the immersion, they were rinsed with deionized water and then vacuum dried at 60℃ to obtain two catalyst precursors PO 4 / CuNiO.

[0075] (3)PO 4 Electrochemical activation of self-loading NiOOH prepared by CuNiOOH:

[0076] The electrochemical activation of NiOOH was completed in a three-electrode system. 4 / CuNiO was used as the working electrode, the counter electrode was platinum, the reference electrode was Hg / HgO, and the electrolyte was 1 mol / L KOH aqueous solution. CV scanning was performed in this system with a scanning range of 0.3 V vs RHE-1.6 V vs RHE, a scanning speed of 50 mV / sec, and a scanning number of 15 circles. After the scanning, PO prepared under different electrodeposition currents was obtained. 4 / CuNiOOH.

[0077] (4) PO produced 4 / Application of CuNiOOH in electrocatalytic conversion of biomass small molecule HMF to FDCA in alkaline solution:

[0078] The HMF electrocatalytic conversion experiment was carried out in an H-type reactor, and the three-electrode system was used for the reaction: the two prepared inorganic ligands PO 4 / CuNiOOH was used as the working electrode, the counter electrode was platinum, the reference electrode was Hg / HgO, the electrolyte of the anode electrolytic cell was a mixed solution of 1 mol / L KOH and 50 mmol / L HMF, and the electrolyte of the cathode electrolytic cell was 1 mol / L KOH, separated by an anion exchange membrane Fuma-FAA-3-50.

[0079] The HMF electrocatalytic conversion performance test was carried out on the CHI660E electrochemical workstation. The LSV test was first performed and the results are shown in Figure 4 In (a), it can be seen that compared with the nickel foam without any catalyst, the starting potentials of the catalysts prepared by the two different electrodeposition currents are lower than 1.37 V vs RHE, and the current density is much higher than 200 mA cm -2The electrocatalytic conversion performance of the catalyst for HMF was verified in the IT test, and the product was detected by HPLC. The Faradaic efficiency results of FDCA are shown in Figure 4 The results of HMF conversion are shown in (b) Figure 4 Middle (c): Within a wide range of 1.45-1.6 V, the conversion rates of FE and HMF of FDCA can reach more than 95%.

[0080] In addition, a cycle test was carried out in a 10 ml 10 mM HMF solution system. The cycle number results are shown in Figure 4 In (d), the number of cycles of the catalysts prepared by different electrodeposition currents is more than 15, and the Faraday efficiency of FDCA can still be maintained above 90% after the cycle. 4 / CuNiOOH not only has a high current density, but also can significantly improve the Faradaic efficiency, HMF conversion rate, and electrode stability of the electrocatalytic HMF to FDCA conversion.

[0081] Embodiment 3:

[0082] Preparation of catalysts with different hydrothermal soaking temperatures:

[0083] A method for preparing and applying an efficient catalyst for electrocatalyzing 5-hydroxymethylfurfural (HMF) to furandicarboxylic acid (FDCA) at a high current density under alkaline conditions is as follows:

[0084] (1)PO 4 Electrodeposition process of CuNiOOH preparation:

[0085] The electrodeposition process was carried out in a three-electrode system, with nickel foam as the working electrode, platinum sheet as the counter electrode, and Hg / HgO as the reference electrode. The electrolyte composition during the electrodeposition process was NiCl 2 6H 2 O, Cu(NO 3 ) 2 6H 2 O and C 6 H 5 Na 3 O 7 ·3H 2 A mixed solution of O, NiCl 2 6H 2 O concentration was 20mmol / L, Cu(NO 3 ) 2 6H 2 O concentration is 80mmol / L, C 6 H 5 Na 3 O 7 ·3H2 The O concentration was 25mmol / L, and the volume of the electrodeposition solution was 30mL. The constant current electrodeposition method was used for loading, and the current density was -50mA / cm 2 The electrodeposition time was 10 min. The deposited working electrode was rinsed with deionized water and then vacuum dried at 60 °C to obtain an amorphous mixed metal substrate.

[0086] (2)PO 4 Phosphorylation hydrothermal soaking process of CuNiOOH preparation:

[0087] The hydrothermal soaking solution is composed of Ni(NO 3 ) 2 6H 2 O,Na 2 HPO 4 , NaNO 3 The mixed solution was ultrasonicated for 30 min, and Ni(NO 3 ) 2 6H 2 O and NaNO 3 The concentration of Na 2 HPO 4 The concentration of was 50mmol / L, the hydrothermal soaking temperature was 40℃, 60℃, and 80℃, and the soaking time was 30min. The substrates were all immersed in the hydrothermal phosphoric acid solution. After the soaking, they were rinsed with deionized water and dried in vacuum at 60℃ to obtain three catalyst precursors PO 4 / CuNiO. .

[0088] (3)PO 4 Electrochemical activation of self-loading NiOOH prepared by CuNiOOH:

[0089] The electrochemical activation of NiOOH was completed in a three-electrode system. 4 / CuNiO was used as the working electrode, the counter electrode was a platinum sheet, the reference electrode was Hg / HgO, and the electrolyte was a 1 mol / L KOH aqueous solution. CV scanning was performed under this system with a scanning range of 0.3 V vs RHE-1.6 V vs RHE, a scanning speed of 50 mV / sec, and a scanning number of 30 circles. After the scanning, PO prepared at different hydrothermal phosphating temperatures was obtained. 4 / CuNiOOH.

[0090] (4) PO produced 4 / Application of CuNiOOH in electrocatalytic conversion of biomass small molecule HMF to FDCA in alkaline solution:

[0091] The HMF electrocatalytic conversion experiment was carried out in an H-type reactor, and the three-electrode system was used for the reaction: the three prepared inorganic ligands PO 4 / CuNiOOH was used as the working electrode, the counter electrode was platinum, the reference electrode was Hg / HgO, the electrolyte of the anode electrolytic cell was a mixed solution of 1 mol / L KOH and 50 mmol / L HMF, and the electrolyte of the cathode electrolytic cell was 1 mol / L KOH, separated by an anion exchange membrane Fuma-FAA-3-50.

[0092] The HMF electrocatalytic conversion performance test was carried out on the CHI660E electrochemical workstation. The LSV test was first performed and the results are shown in Figure 5 In (a), it can be seen that compared with the catalysts obtained by electrodeposition without hydrothermal phosphating, the starting potentials of the catalysts prepared at three different hydrothermal immersion temperatures are all lower than 1.37 V vs RHE, and the current density is much higher than 200 mA cm -2 The electrocatalytic conversion performance of the catalyst for HMF was verified in the IT test, and the product was detected by HPLC. The Faradaic efficiency results of FDCA are shown in Figure 5 The results of HMF conversion are shown in (b) Figure 5 (c): In the wide range of 1.45-1.6V, the conversion rates of FE and HMF of FDCA can reach more than 95%. In addition, a cycle test was carried out in a 10ml 10mM HMF solution system. The cycle number results are shown in Figure 5 In (d), the catalysts prepared at different hydrothermal soaking temperatures can be cycled for more than 16 times, and the Faraday efficiency of FDCA can still be maintained above 90% after the cycle. 4 / CuNiOOH not only has a high current density, but also can significantly improve the Faradaic efficiency, HMF conversion rate, and electrode stability of the electrocatalytic HMF to FDCA conversion.

[0093] Embodiment 4:

[0094] Preparation of catalysts with different hydrothermal soaking times:

[0095] A method for preparing and applying an efficient catalyst for electrocatalyzing 5-hydroxymethylfurfural (HMF) to furandicarboxylic acid (FDCA) at a high current density under alkaline conditions is as follows:

[0096] (1)PO 4 / CuNiOOH preparation electrodeposition process:

[0097] The electrodeposition process was carried out in a three-electrode system, with nickel foam as the working electrode, platinum sheet as the counter electrode, and Hg / HgO as the reference electrode. The electrolyte composition during the electrodeposition process was NiCl 26H 2 O, Cu(NO 3 ) 2 6H 2 O and C 6 H 5 Na 3 O 7 ·3H 2 A mixed solution of O, NiCl 2 6H 2 O concentration was 20mmol / L, Cu(NO 3 ) 2 6H 2 O concentration is 80mmol / L, C 6 H 5 Na 3 O 7 ·3H 2 The O concentration was 50mmol / L, and the volume of the electrodeposition solution was 30mL. The constant current electrodeposition method was used for loading, and the current density was -50mA / cm 2 The electrodeposition time was 10 min. The deposited working electrode was rinsed with deionized water and then vacuum dried at 60 °C to obtain an amorphous mixed metal substrate.

[0098] (2)PO 4 Phosphorylation hydrothermal soaking process of CuNiOOH preparation:

[0099] The hydrothermal soaking solution is composed of Ni(NO 3 ) 2 6H 2 O,Na 2 HPO 4 , NaNO 3 The mixed solution was ultrasonicated for 30 min, and Ni(NO 3 ) 2 6H 2 O and NaNO 3 The concentration of Na 2 HPO 4 The concentration of was 50mmol / L, the hydrothermal soaking temperature was 80℃, the hydrothermal soaking time was 30min and 12h, the substrates were all immersed in the hydrothermal phosphoric acid solution, after the soaking, they were rinsed with deionized water and dried in vacuum at 60℃ to obtain two catalyst precursors PO 4 / CuNiO. .

[0100] (3)PO 4 Electrochemical activation of self-loading NiOOH prepared by CuNiOOH:

[0101] The electrochemical activation of NiOOH was completed in a three-electrode system. 4 / CuNiO was used as the working electrode, the counter electrode was a platinum sheet, the reference electrode was Hg / HgO, and the electrolyte was a 1 mol / L KOH aqueous solution. CV scanning was performed under this system with a scanning range of 0.3 V vs RHE-1.6 V vs RHE, a scanning speed of 50 mV / sec, and a scanning number of 30 circles. After the scanning, PO prepared by hydrothermal phosphating for different insulation times was obtained. 4 / CuNiOOH.

[0102] (4) PO produced 4 / Application of CuNiOOH in electrocatalytic conversion of biomass small molecule HMF to FDCA in alkaline solution:

[0103] The HMF electrocatalytic conversion experiment was carried out in an H-type reactor, and the three-electrode system was used for the reaction: the two prepared inorganic ligands PO 4 / CuNiOOH was used as the working electrode, the counter electrode was platinum, the reference electrode was Hg / HgO, the electrolyte of the anode electrolytic cell was a mixed solution of 1 mol / L KOH and 50 mmol / L HMF, and the electrolyte of the cathode electrolytic cell was 1 mol / L KOH, separated by an anion exchange membrane Fuma-FAA-3-50.

[0104] The HMF electrocatalytic conversion performance test was carried out on the CHI660E electrochemical workstation. The LSV test was first performed and the results are shown in Figure 6 In (a), it can be seen that compared with the catalyst obtained by electrodeposition without hydrothermal phosphating, the starting potential of the catalyst prepared by phosphating at two different hydrothermal immersion times of 30 min and 12 h was lower than 1.37 V vs RHE, and the current density was much higher than 200 mA cm -2 The electrocatalytic conversion performance of the catalyst for HMF was verified in the IT test, and the product was detected by HPLC. The Faradaic efficiency results of FDCA are shown in Figure 6 The results of HMF conversion are shown in (b) Figure 6 Middle (c): Within a wide range of 1.45-1.6 V, the conversion rates of FE and HMF of FDCA can reach more than 95%.

[0105] In addition, a cycle test was carried out in a 10 ml 10 mM HMF solution system. The cycle number results are shown in Figure 6 In (d), the catalysts prepared by phosphating and heat preservation at different hydrothermal soaking times can be cycled for more than 16 times, and the Faraday efficiency of FDCA can still be maintained above 90% after the cycle. 4 / CuNiOOH not only has a high current density, but also can significantly improve the Faradaic efficiency, HMF conversion rate, and electrode stability of the electrocatalytic HMF to FDCA conversion.

[0106] The above are only preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a catalyst for electrocatalytic conversion of HMF into FDCA, characterized in that: The preparation method comprises the following steps: Step 1, preparing an amorphous mixed metal substrate by electrodeposition, wherein the electrodeposition electrolyte comprises a mixed solution of divalent nickel ions, divalent copper ions and sodium citrate, wherein the concentration ratio of nickel ions to copper ions is 0.1-5, Electrodeposition is carried out in a multi-electrode system using a constant current load to prepare an amorphous mixed metal substrate; Step 2, preparing a catalyst precursor PO4 / CuNiO in situ by electrochemical in-situ synthesis, wherein the electrochemical in-situ synthesis is to hydrothermally immerse the amorphous mixed metal substrate prepared in step 1 in a hydrothermal immersion solution, and then rinse and dry after immersion to obtain the catalyst precursor PO4 / CuNiO; Step 3, preparing the catalyst inorganic ligand PO4 / CuNiOOH for electrocatalytic conversion of HMF to FDCA by electrochemical activation, and electrochemically activating the catalyst precursor PO4 / CuNiO prepared in step 2, wherein the electrochemical activation is performed by CV scanning under a three-electrode system, and a catalyst for electrocatalytic conversion of HMF to FDCA is obtained after the scanning.

2. The method for preparing a catalyst for electrocatalytic conversion of HMF into FDCA according to claim 1, characterized in that: In step 1, the multi-electrode system includes a two-electrode system and a three-electrode system, wherein the working electrode is carbon fiber or foam metal, and the counter electrode is one of inert electrodes such as platinum sheet, graphite sheet, carbon paper, etc.; the reference electrode in the three-electrode system is one of Ag / AgCl, saturated calomel, and Hg / HgO.

3. The method for preparing a catalyst for electrocatalytic conversion of HMF into FDCA according to claim 1, characterized in that: In step 1, the electrodeposition electrolyte includes a mixed solution of divalent nickel ions, divalent copper ions and sodium citrate, the nickel ion concentration is 10mmol / L-100mmol / L, the copper ion concentration is 10mmol / L-100mmol / L, and the sodium citrate concentration is 1mmol / L-50mmol / L.

4. The method for preparing a catalyst for electrocatalytic conversion of HMF into FDCA according to claim 1, characterized in that: In step 1, the method of using constant current for loading is to use constant current electrodeposition method for loading during electrodeposition, and the current density is -10mA / cm 2 To -120mA / cm 2 The electrodeposition time is 5 min to 30 min. The deposited working electrode is rinsed with deionized water and then vacuum dried at 60 °C to obtain an amorphous mixed metal substrate.

5. The method for preparing a catalyst for electrocatalytic conversion of HMF into FDCA according to claim 1, characterized in that: In step 2, the hydrothermal soaking liquid is a mixed solution of Ni(NO3)2·6H2O, Cu(NO3)2·6H2O and Na2HPO4, NaNO3. The prepared solution is ultrasonicated to make it evenly dispersed, and then soaked. The hydrothermal soaking temperature is 40°C-100°C, and the hydrothermal soaking time is 30min-12h. After the soaking, it is rinsed with deionized water and vacuum dried at 60°C to obtain the catalyst precursor PO4 / CuNiO.

6. The method for preparing a catalyst for electrocatalytic conversion of HMF into FDCA according to claim 6, characterized in that: The concentrations of Ni(NO3)2·6H2O and NaNO3 in the hydrothermal soaking solution are 20mmol / L-50mmol / L, and the concentration of Na2HPO4 is 50mmol / L-100mmol / L.

7. The method for preparing a catalyst for electrocatalytic conversion of HMF into FDCA according to claim 1, characterized in that: In the three-electrode system, PO4 / CuNiO is the working electrode, the counter electrode is one of the inert electrodes such as platinum sheet, graphite sheet, carbon paper, etc., and the reference electrode is Hg / HgO.

8. The method for preparing a catalyst for electrocatalytic conversion of HMF into FDCA according to claim 1, characterized in that: The CV scan is performed under a three-electrode system, the electrolyte is a 0.1 mol / L-2 mol / L KOH aqueous solution, the scanning range is 0.3 V vs RHE-1.6 V vs RHE, the scanning speed is 5-100 mV / sec, the scanning number of circles is 10-50 circles, and PO4 / CuNiOOH is obtained after the scanning.

9. A catalyst for electrocatalytic conversion of HMF into FDCA, prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the catalyst for electrocatalytic conversion of HMF into FDCA prepared according to claim 9 in an electrocatalytic system for electrocatalytic conversion of biomass small molecule HMF into FDCA in an alkaline solution.

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