CN117187841A

CN117187841A - Large-size 5-hydroxymethylfurfural oxidation electrocatalyst and preparation method thereof

Info

Publication number: CN117187841A
Application number: CN202311125907.6A
Authority: CN
Inventors: 孙立成; 丁国恒; 呼斯楞; 李志恒
Original assignee: Westlake University
Current assignee: Westlake University
Priority date: 2023-09-01
Filing date: 2023-09-01
Publication date: 2023-12-08

Abstract

The application belongs to the technical field of synthesis of oxidation electrocatalysts, in particular relates to a large-size electrocatalyst for oxidation of 5-hydroxymethylfurfural, and particularly discloses a preparation method and application thereof. The preparation method of the large-size 5-hydroxymethylfurfural oxidation electrocatalyst takes copper salt solution and nickel salt solution as load active ingredients, and can utilize quick soaking in second-level time under the conditions of normal temperature and normal pressure to successfully synthesize the novel HMF oxidation electrocatalystAnd (3) a chemical agent. The application relates to a novel NiCuO _x The catalyst has excellent HMF oxidation activity and stability, and the synthesis method is simple, low in preparation cost and easy for large-scale production, thereby meeting the requirement of further industrialization.

Description

Large-size 5-hydroxymethylfurfural oxidation electrocatalyst and preparation method thereof

Technical Field

The application belongs to the technical field of synthesis of oxidation electrocatalysts, in particular relates to a large-size electrocatalyst for oxidation of 5-hydroxymethylfurfural, and particularly discloses a preparation method and application thereof.

Background

For a long time, due to the large amount of use of the traditional petroleum-based polymer materials, the production and the life of human beings are brought with extremely serious environmental problems such as white pollution, and the growing shortage of fossil resources is added, so that people are forced to find novel environment-friendly alternative materials. The bio-based plastic material is considered as an ideal substitute for the traditional plastic material because of the advantages of green and wide raw material sources, low cost, easy degradation, environmental friendliness, excellent physical and chemical properties and the like.

Polyethylene furandicarboxylate (polyethylene furanoate, PEF) is a novel bio-based polymer material. It is considered to be one of the most potential and promising key materials for the replacement of petroleum-based polyethylene terephthalate (Polyethylene terephthalate, PET) due to its excellent air-barrier properties, thermal stability and mechanical properties. The 2,5-furandicarboxylic acid (2, 5-Furandicarboxylic acid, FDCA) is a key monomer for synthesizing PEF, and the synthesis process has important significance for synthesizing PEF materials.

Currently, the main approach for industrially synthesizing FDCA is a traditional thermocatalytic method, namely, the FDCA is prepared by oxidizing 5-Hydroxymethylfural (HMF) serving as a raw material. The process generally employs a noble metal-based solid catalyst such as Pt, au, pd, etc., and a high-pressure oxidizing gas (> 5 atm), etc., as an oxidizing agent, and the oxidation process is required to be performed under high temperature (100-200 ℃). The production method is widely used in industry because of early research and mature process. However, the cost of the process equipment is high due to high cost and rare reserves of noble metals, so that the large-scale production and application are difficult; moreover, the severity of the reaction conditions also increases the safety risk of the operation of the equipment and increases the installation and maintenance costs of the equipment; the process can generate a great deal of energy consumption and CO in the reaction process ₂ And the greenhouse gases can also bring serious environmental pollution.

Electric drierChemical oxidation is a catalytic oxidation method that accelerates the charge transfer at the interface between the electrode and the electrolyte. The electrocatalytic process has the advantages of mild reaction conditions, high reaction energy efficiency and capability of being carried out at normal temperature and normal pressure; furthermore, the electrocatalytic process is described as H ₂ O is a high-activity oxygen-containing species generated in situ by raw material electrochemistry and is used as an oxidant, and the method has the advantages of green, environment-friendly and carbon-free emission; the process can be catalyzed by adopting a non-noble metal-based catalyst, and has low process cost, large development potential and wide market prospect. At present, the preparation of FDCA by oxidizing HMF in an electrocatalytic manner becomes a research hotspot in the field, and various problems existing in the traditional thermocatalytic process can be effectively solved.

However, the process for preparing FDCA based on electrocatalytic oxidation of HMF is still in the laboratory research stage at present, and industrialization and commercialization have not been achieved yet. The main problems restricting the further development of the electrocatalytic HMF oxidation process include: the reported preparation methods of the non-noble metal-based catalyst are mostly solvothermal synthesis, high-temperature calcination and the like, the operation is complex and complicated, the reaction conditions are harsh, the synthesis of large-size samples is not facilitated, and the further large-scale production is difficult; meanwhile, most catalysts have the problems of low current density and poor stability, and the performance of catalyzing the oxidation of HMF is not ideal, so that the industrial performance requirement cannot be met.

For example, chinese patent CN116377495A discloses a method for oxidizing 5-hydroxymethylfurfural by using a nickel-molybdenum bimetallic electrocatalyst, which is synthesized by multi-step reactions such as solvothermal reaction, calcination reduction and the like, and has the problems of more process steps, difficult operation, high process energy consumption (the highest temperature can reach 600 ℃), high pressure and H ₂ The use of the catalyst greatly increases the safety risk of preparation, and is difficult to realize further amplified production; meanwhile, under the constant potential of 1.45V, the current density of the catalyst for catalyzing the oxidation of HMF is only 10mA cm ^-2 On the left and right, the requirement of further industrialization cannot be met. As another example, chinese patent CN115896840a discloses a catalyst for electrocatalytic conversion of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid with high current density and a preparation method thereof, which synthesizes the catalyst by Fenton-like method and realizes the purpose under high current densityOxidation of 5-hydroxymethylfurfural; however, this method requires the use of H ₂ O ₂ As a synthetic raw material, the property of easy decomposition and instability increases the operation difficulty, reduces the reproducibility of the method and has high H concentration ₂ O ₂ The use of (2) also increases the safety risk to some extent; the reaction stock solution cannot be recycled, so that the process cost is increased to a certain extent; in particular, the method produces samples of relatively small size (only 1-3cm ² ) Its universality is general; in addition, the stability of the catalyst still has a large improvement space.

Therefore, the development of a high-efficiency and stable large-size non-noble metal-based electrocatalyst for the oxidation of 5-hydroxymethylfurfural is expected in the field, and has positive significance for the development of an electrocatalytic oxidation process for preparing FDCA (fully drawn yarn) by HMF (high-purity hydrogen peroxide).

Disclosure of Invention

Therefore, the technical problem to be solved by the application is to provide the large-size non-noble metal-based electrocatalyst for 5-hydroxymethylfurfural oxidation, which has the advantages of high efficiency, stability, simplicity in operation, mild condition, low safety risk, low synthesis cost, good reproducibility and easiness in amplified production;

the second technical problem to be solved by the application is to provide a preparation method and application of the large-size non-noble metal-based electrocatalyst for oxidation of 5-hydroxymethylfurfural.

In order to solve the technical problems, the preparation method of the large-size 5-hydroxymethylfurfural oxidation electrocatalyst comprises the following steps:

(1) Respectively preparing copper salt solution and/or nickel salt solution to obtain metal salt solution;

(2) And (3) adding a substrate material into the metal salt solution for dipping treatment, and drying to obtain the metal salt.

Specifically, in the step (1), the copper salt solution includes a copper sulfate solution and/or a copper nitrate solution;

preferably, the concentration of the copper salt solution is 25-600mmol/L; more preferably 100-300mmol/L;

preferably, the solvent of the copper salt solution includes conventional solvents such as water and alcohol solvents, and more preferably, an aqueous solution.

Specifically, in the step (1), the nickel salt solution includes a nickel nitrate solution and/or a nickel sulfate solution;

preferably, the concentration of the nickel salt solution is 25-600mmol/L; more preferably 100-300mmol/L;

preferably, the solvent of the nickel salt solution includes conventional solvents such as alcohol solvents, water and the like, and more preferably, ethanol solution.

Specifically, in the step (1), the metal salt solution includes a mixed solution of a copper salt solution and a nickel salt solution;

in the metal salt solution, the molar ratio of nickel ions to copper ions in the suspension is >0-4:4- >0;

preferably, the molar ratio of nickel ions to copper ions in the metal salt solution is 1-3:3-1;

preferably, the molar ratio of nickel ions to copper ions in the metal salt solution is 2:2.

Specifically, the step of mixing the metal salt solution includes a step of adding the copper salt solution dropwise to the nickel salt solution;

preferably, the dripping time is controlled to be 5-20min.

Specifically, in the step (2), the size of the base material is (1.5-10) cm× (1.5-10) cm, and the thickness is 0.2-1.6mm;

preferably, the substrate material comprises at least one of nickel foam, iron foam, cobalt foam, copper foam or carbon paper substrate.

Specifically, in the step (2), the time of the impregnation treatment is 10s-10min;

preferably, in the step (2), the method further includes a step of pretreating the base material;

preferably, the pretreatment step includes a step of oxidizing and cleaning the base material;

preferably, the oxidation step comprises the step of carrying out oxidation treatment for 30-120min at 25-100 ℃ by adopting dilute hydrochloric acid or nitric acid;

preferably, the cleaning step comprises the step of ultrasonic cleaning by using ethanol and/or acetone as a solvent.

Preferably, in the step (2), the method further comprises a step of washing and drying the impregnated electrocatalyst.

The application also discloses a large-size 5-hydroxymethylfurfural oxidation electrocatalyst prepared by the method;

preferably, the size of the 5-hydroxymethylfurfural oxidation electrocatalyst is (1.5-10) cm× (1.5-10) cm, and the thickness is 0.2-1.6mm. The 5-hydroxymethylfurfural oxidation electrocatalyst provided by the application has better performance under the conventional size, even a substrate with a large size (about 10cm multiplied by 10 cm) can still realize uniform active load, and the performance stability is better.

The application also discloses application of the large-size 5-hydroxymethylfurfural oxidation electrocatalyst in a process for preparing FDCA by electrocatalytic oxidation of HMF.

The application also discloses a process for preparing FDCA by electrocatalytic oxidation of HMF, which comprises the step of preparing FDCA by electrocatalytic oxidation by taking HMF as a raw material in the presence of the catalyst.

Specifically, in the process for preparing FDCA by electrocatalytic oxidation of HMF, electrochemical workstations can be selected from direct-current electrochemical workstations of different types such as Autolab PGSTAT302N, autolabvionic, CHI760 or CHI 1140;

the reaction vessel can select H-type electrolytic cells with different specifications such as 10mL, 50mL and the like;

the reference electrode can be Hg/HgO or Ag/AgCl, wherein the Hg/HgO electrode is filled with 1M KOH solution, and the Ag/AgCl electrode is filled with 3M KCl or saturated KCl solution;

the counter electrode can be selected from platinum mesh, graphite rod, etc.;

the working electrode can be selected from platinum clamp electrode, stainless steel clamp electrode, etc.;

the chambers of the H-type electrolytic cell 2 can be separated by selecting Nafion117, nafion212 and other cation exchange membranes or FAA-3-50, FAB-PK-130 and other anion exchange membranes;

the electrolyte can be 1M KOH or NaOH and the like containing HMF with different concentrations; for example, 10-100mM HMF+0.5-1.5M KOH/NaOH.

Specifically, in the process for preparing FDCA by electrocatalytic oxidation of HMF, a test method is selected from cyclic sweep voltammetry, linear sweep voltammetry, constant voltage electrolysis and the like.

Specifically, the cyclic scanning voltammetry scanning voltage range is 0.2-0.8V (vs Hg/HgO), the scanning speed is 10-100mV/s, and the scanning turns are 1-25;

specifically, the scanning voltage range of the linear scanning voltammetry is 0.2-0.8V (vs. Hg/HgO), the scanning speed is 2-10mV/s, and the scanning turns are 1;

specifically, the constant voltage electrolytic method sets the voltage range to be 0.50-0.65V (vs. Hg/HgO), and the electrolytic time is 30-60min;

specifically, the stirring speed of the magnet during the test can be set to be in the range of 0-2000rpm.

According to the preparation method of the large-size 5-hydroxymethylfurfural oxidation electrocatalyst, a copper salt solution and a nickel salt solution are used as load active ingredients, and even load of active metal salts can be realized through rapid soaking in second-level time under the condition of normal temperature and normal pressure, so that the novel HMF oxidation electrocatalyst is successfully synthesized. The preparation method of the catalyst has the advantages of simple and rapid operation, short synthesis time, small safety risk, good reproducibility, easy preparation of large-size samples and easy mass production.

The preparation method of the catalyst is particularly suitable for the supported preparation of large-size substrate materials, can be used for synthesizing large-size catalysts, has uniform growth of metal salt active components, has no attenuation in performance compared with small-size catalysts, and can realize the effective processing of large-size oxidation electrocatalysts. The large-size catalyst can be used for assembling a large-size electrocatalytic device, so that the HMF oxidation efficiency can be remarkably improved, the FDCA yield is improved, the process cost is reduced, the method is closer to industrial practical application, and the method has more industrial prospect and potential.

Compared with the traditional synthetic methods such as solvothermal synthesis and high-temperature calcination, the preparation method of the catalyst disclosed by the application has the problems of high temperature and high pressure, complex operation, high safety risk, long preparation time (hours or even days) and the like, the preparation method only needs one step of soaking, is simple in step and short in time (seconds or minutes), can be implemented at normal temperature and normal pressure, has small safety risk and mild condition, and has further industrial development prospect.

According to the preparation method of the large-size 5-hydroxymethylfurfural oxidation electrocatalyst, the catalyst synthesis stock solution is only a metal salt solution, so that the catalyst can be recycled, and the preparation cost of the catalyst is reduced; meanwhile, the method is also suitable for different substrates, such as foam iron, foam cobalt, foam copper, carbon fiber paper and the like, has certain universality and wide application prospect, and provides an important reference for the design synthesis of the HMF oxidation electrocatalyst and the preparation and production of the amplified catalyst.

The large-size 5-hydroxymethylfurfural oxidation electrocatalyst is a novel NiCuO _x The catalyst can effectively inhibit oxygen evolution reaction of the nickel-based catalyst by introducing copper phase with poor oxygen evolution reaction activity, and effectively improve oxidation activity and stability of HMF. The application relates to a novel NiCuO _x The catalyst, even though of large size, still exhibits excellent HMF oxidation performance, particularly excellent stability performance, meeting the industrial performance requirements.

Drawings

In order that the application may be more readily understood, a more particular description of the application will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings, in which,

FIG. 1 is a scanning electron microscope image of a catalyst prepared in example 1;

FIG. 2 is a transmission electron microscope image of the catalyst prepared in example 1;

FIG. 3 is a selected area electron diffraction pattern of the catalyst prepared in example 1;

FIG. 4 is a scanning electron microscope image of the catalyst prepared in example 5;

FIG. 5 is a scanning electron microscope image of the catalyst prepared in example 6;

FIG. 6 is a scanning electron microscope image of the catalyst prepared in example 7;

FIG. 7 is a scanning electron microscope image of the catalyst prepared in example 8;

FIG. 8 is a photograph of a catalyst prepared in example 8;

FIG. 9 is an LSV plot of HMFOR versus OER for a catalyst oxidation electrocatalytic process prepared as per example 1 (containing 5 sets of replicates);

FIG. 10 is a LSV plot of HMFOR versus OER for a catalyst oxidation electrocatalytic process prepared as per example 2 (including other different nickel and copper metal ion molar ratio optimized samples);

FIG. 11 is a LSV plot of HMFOR versus OER for a catalyst oxidation electrocatalytic process prepared as per example 3 (including other samples optimized for total concentration of different metal ions);

FIG. 12 is a LSV plot of HMFOR versus OER for a catalyst oxidation electrocatalytic process prepared as per example 4 (including other different soak time optimized samples);

FIG. 13 is a LSV plot of HMFOR for a catalyst prepared according to the method of examples 5-7 and a corresponding blank substrate subjected to an oxidative electrocatalytic process (i.e., a different substrate optimized sample);

FIG. 14 is an LSV plot of HMFOR versus OER for a catalyst oxidation electrocatalytic process prepared as per example 8 (containing 5 sets of parallel runs);

FIG. 15 is a plot of FDCA Faraday efficiency (FE,%) versus Yield (Yield,%) for the HMFOR stability test of the catalyst oxidation electrocatalytic process prepared in example 1;

FIG. 16 is a scanning electron microscope image of the catalyst prepared in comparative example 1;

FIG. 17 is a scanning electron microscope image of the catalyst prepared in comparative example 2;

FIG. 18 is a scanning electron microscope image of the catalyst prepared in comparative example 3;

FIG. 19 is an LSV plot of HMFOR for the catalytic oxidation electrocatalytic process of example 1 and comparative examples 1-3.

Detailed Description

Example 1

Treating a foam nickel substrate with the size of 1.5cm multiplied by 2cm and the thickness of 1.0mm with dilute hydrochloric acid at 25-50 ℃ for 1h, then ultrasonically cleaning with ethanol/acetone mixed solution to remove oxides and organic impurities on the surface of the substrate, and drying the foam nickel substrate for later use.

Ni (NO) of 300mmol/L was respectively disposed ₃ ) ₂ ·9H ₂ O in absolute ethanol (denoted as A solution) and 100mmol/L CuSO ₄ ·5H ₂ The aqueous solutions of O (designated as B solutions) were 10mL each. And dripping the prepared solution B into the solution A which is continuously stirred at a constant speed, and continuously stirring for 10min to obtain a mixed suspension (marked as solution C), wherein the molar ratio of nickel ions to copper ions is 3:1.

Transferring the solution C into a glass container, and carrying out ultrasonic treatment and standing; immersing the dried foam nickel substrate into the solution C for 10s. And then taking out the obtained catalyst, and cleaning and drying the catalyst to obtain the catalyst.

Scanning electron microscopy, transmission electron microscopy and selected area electron diffraction patterns of the catalyst prepared in this example are shown in figures 1-3, respectively. It can be seen that the catalyst prepared in this example exhibited a uniform nanoneedle morphology and that the catalyst phase was predominantly amorphous.

The performance of the resulting catalyst was tested using a 3-electrode system and an H-cell. The H-type electrolytic cell 2 chamber was separated by a cation exchange membrane Nafion212 using 50mM HMF+1M KOH as the electrolyte, hg/HgO and a platinum mesh as the reference electrode and the counter electrode, respectively. Catalyst performance was tested using linear sweep voltammetry at a sweep rate of 10mV s ^-1 The potential range is 0.2-0.8V (vs. Hg/HgO), and the current density can reach 650mAcm ^-2 Under constant potential electrolysis of 0.55V (vs. Hg/HgO), the Faraday efficiency of FDCA can reach 95% and the yield is 91%.

Example 2

Treating a foam nickel substrate with the size of 1.5cm multiplied by 2cm and the thickness of 1.0mm with dilute hydrochloric acid at 25-50 ℃ for 1h, then ultrasonically cleaning with an ethanol/acetone mixed solution to remove oxides and organic impurities on the surface of the substrate, and finally drying the substrate for later use.

Ni (NO) of 200mmol/L was respectively disposed ₃ ) ₂ ·9H ₂ Absolute ethanol solution of O (solution A)And 200mmol/L CuSO ₄ ·5H ₂ 10mL of each of the aqueous solutions (B solutions) of O; and then dripping the prepared solution B into the solution A which is continuously stirred at a constant speed, and continuously stirring for 10min to obtain a mixed suspension (solution C), wherein the molar ratio of nickel ions to copper ions is 2:2.

Transferring the solution C into a glass container, and carrying out ultrasonic treatment and standing; immersing the dried foam nickel substrate into the solution for 10s, taking out the catalyst, cleaning and drying for later use.

The catalyst performance was tested using a 3-electrode system and an H-cell. 50mM HMF+1MKOH is used as electrolyte, hg/HgO and a platinum net are respectively used as a reference electrode and a counter electrode, a positive ion exchange membrane Nafion212 is used for separating the chamber of an H-type electrolytic cell 2, and a linear sweep voltammetry method is used for testing the performance of the catalyst, wherein the sweep speed is 10mV s ^-1 The potential range is 0.2-0.8V (vs. Hg/HgO), and the current density can reach 380mAcm ^-2 Under constant potential electrolysis of 0.55V (vs. Hg/HgO), the Faraday efficiency of FDCA can reach 93 percent, and the yield is 88 percent.

Example 3

Ni (NO) of 75mmol/L was respectively disposed ₃ ) ₂ ·9H ₂ Absolute ethanol solution of O (solution A) and 25mmol/L CuSO ₄ ·5H ₂ 10mL of each of the aqueous solutions (B solutions) of O; and then dripping the prepared solution B into the solution A which is continuously stirred at a constant speed, and continuously stirring for 10min to obtain a mixed suspension (solution C), wherein the molar ratio of nickel ions to copper ions is 3:1.

Then transferring the solution C into a glass container, performing ultrasonic treatment and standing; immersing the dried foam nickel substrate into the solution for 10s, taking out the catalyst, cleaning and drying for later use.

The catalyst performance was tested using a 3-electrode system and an H-cell. 50mM HMF+1MKOH is used as electrolyte, hg/HgO and platinum net are respectively used as reference electricityThe electrode and counter electrode were separated by a cation exchange membrane Nafion212 from the H-cell 2 chamber and the catalyst performance was tested using linear sweep voltammetry at a sweep rate of 10mV s ^-1 The potential range is 0.2-0.8V (vs. Hg/HgO), and the current density can reach 340mAcm ^-2 Under constant potential electrolysis of 0.55V (vs. Hg/HgO), the Faraday efficiency of FDCA can reach 91% and the yield is 85%.

Example 4

Ni (NO) of 300mmol/L was respectively disposed ₃ ) ₂ ·9H ₂ Absolute ethanol solution of O (solution A) and 100mmol/L CuSO ₄ ·5H ₂ 10mL of each of the aqueous solutions (B solutions) of O; and then dripping the prepared solution B into the solution A which is continuously stirred at a constant speed, and continuously stirring for 10min to obtain a mixed suspension (solution C), wherein the molar ratio of nickel ions to copper ions is 3:1.

Then transferring the solution C into a glass container, performing ultrasonic treatment and standing; immersing the dried foam nickel substrate into the solution for 10min, taking out the catalyst, cleaning and drying for later use.

Catalyst performance was tested using a 3 electrode system and an H-cell, 50mM HMF+1MKOH as electrolyte, hg/HgO and a platinum mesh as reference and counter electrodes, respectively, and the H-cell 2 chamber was separated by a cation exchange membrane Nafion212, and catalyst performance was tested using a linear sweep voltammetry at a sweep rate of 10mV s ^-1 The potential range is 0.2-0.8V (vs. Hg/HgO), and the current density can reach 330mAcm ^-2 Under constant potential electrolysis of 0.55V (vs. Hg/HgO), the Faraday efficiency of FDCA can reach 91% and the yield is 83%.

Example 5

Treating a foam iron substrate with the size of 1.5cm multiplied by 2cm and the thickness of 0.75mm with dilute hydrochloric acid at 25 ℃ for 30s, then ultrasonically cleaning with an ethanol/acetone mixed solution to remove oxides and organic impurities on the surface of the substrate, and finally drying the substrate for later use.

The scanning electron microscope image of the catalyst prepared in this example is shown in FIG. 4. As can be seen, the catalyst prepared in this example exhibited a uniform nanoplatelet morphology.

Catalyst performance was tested using a 3 electrode system and an H-cell, 50mM HMF+1MKOH as electrolyte, hg/HgO and a platinum mesh as reference and counter electrodes, respectively, and the H-cell 2 chamber was separated by a cation exchange membrane Nafion212, and catalyst performance was tested using a linear sweep voltammetry at a sweep rate of 10mV s ^-1 The potential range is 0.2-0.8V (vs. Hg/HgO), and the current density can reach 280mA cm ^-2 Under constant potential electrolysis of 0.65V (vs. Hg/HgO), the Faraday efficiency of FDCA can reach 95% and the yield is 87%.

Example 6

Treating a foam copper substrate with the size of 1.5cm multiplied by 2cm and the thickness of 0.5mm with dilute hydrochloric acid at 25-50 ℃ for 2 hours, then ultrasonically cleaning with an ethanol/acetone mixed solution to remove oxides and organic impurities on the surface of the substrate, and finally drying the substrate for later use.

The scanning electron microscope image of the catalyst prepared in this example is shown in FIG. 5. It can be seen that the catalyst prepared in this example was uniformly dispersed on the surface of the substrate in the form of nano-sized blocks.

Catalyst performance was tested using a 3 electrode system and an H-cell, 50mM HMF+1MKOH as electrolyte, hg/HgO and a platinum mesh as reference and counter electrodes, respectively, and the H-cell 2 chamber was separated by a cation exchange membrane Nafion212, and catalyst performance was tested using a linear sweep voltammetry at a sweep rate of 10mV s ^-1 The potential range is 0.2-0.8V (vs. Hg/HgO), and the current density can reach 280mAcm ^-2 Under constant potential electrolysis of 0.65V (vs. Hg/HgO), the Faraday efficiency of FDCA can reach 86% and the yield is 82%.

Example 7

Treating a foamed cobalt substrate with the size of 1.5cm multiplied by 2cm and the thickness of 1.6mm with dilute hydrochloric acid at 25-50 ℃ for 2 hours, then ultrasonically cleaning with an ethanol/acetone mixed solution to remove oxides and organic impurities on the surface of the substrate, and finally drying the substrate for later use.

The scanning electron microscope of the catalyst prepared in this example is shown in FIG. 6. As can be seen, the catalyst prepared in this example exhibited a uniform nanoplatelet morphology.

The catalyst performance was tested using a 3-electrode system and an H-cell,50mM HMF+1MKOH is used as electrolyte, hg/HgO and a platinum net are respectively used as a reference electrode and a counter electrode, a positive ion exchange membrane Nafion212 is used for separating the chamber of an H-type electrolytic cell 2, and a linear sweep voltammetry method is used for testing the performance of the catalyst, wherein the sweep speed is 10mV s ^-1 The potential range is 0.2-0.8V (vs. Hg/HgO), and the current density can reach 230mAcm ^-2 Under constant potential electrolysis of 0.55V (vs. Hg/HgO), the Faraday efficiency of FDCA can reach 88% and the yield is 79%.

Example 8

Treating a foam nickel substrate with the size of 10cm multiplied by 10cm and the thickness of 1.0mm with dilute hydrochloric acid at 25-50 ℃ for 2 hours, then ultrasonically cleaning with an ethanol/acetone mixed solution to remove oxides and organic impurities on the surface of the substrate, and finally drying the substrate for later use.

Ni (NO) of 300mmol/L was respectively disposed ₃ ) ₂ ·9H ₂ Absolute ethanol solution of O (solution A) and 100mmol/L CuSO ₄ ·5H ₂ 500mL of each of the aqueous solutions (B solutions) of O; and then dripping the prepared solution B into the solution A which is continuously stirred at a constant speed, and continuously stirring for 30min to obtain a mixed suspension (solution C), wherein the molar ratio of nickel ions to copper ions is 3:1.

then transferring the solution C into a glass container, performing ultrasonic treatment and standing; immersing the dried foam nickel substrate into the solution for 1min, taking out the catalyst, cleaning and drying for later use. The scanning electron microscope of the catalyst prepared in this example is shown in fig. 7, and the physical photograph is shown in fig. 8. As can be seen, the catalysts prepared in this example exhibited uniformity at different scales.

Catalyst performance was tested using a 3 electrode system and an H-cell, 50mM HMF+1MKOH as electrolyte, hg/HgO and a platinum mesh as reference and counter electrodes, respectively, and the H-cell 2 chamber was separated by a cation exchange membrane Nafion212, and catalyst performance was tested using a linear sweep voltammetry at a sweep rate of 10mV s ^-1 The potential range is 0.2-0.8V (vs. Hg/HgO), and the current density can reach 610mAcm ^-2 Under constant potential electrolysis of 0.55V (vs. Hg/HgO), the Faraday efficiency of FDCA can reach 95% and the yield is 91%.

Comparative example 1

The catalyst of this comparative example was prepared in the same manner as in example 1 except that the substrate was selected to have a size of 10 cm. Times.10 cm and a thickness of 1.0mm, 500mL each of the copper salt solution and the nickel salt solution was added with 100mL of H having a mass fraction of 30% ₂ O ₂ And (3) preparing a suspension of the C solution together. After adding H ₂ O ₂ In the process of (2), the suspension of the C solution is gradually changed from a clear solution to a dark green suspension, and a large amount of dark green precipitate is generated.

Then, the C solution was transferred to a glass vessel, and after a short period of ultrasound, a large amount of H was present in the standing C solution ₂ O ₂ Decomposing the generated bubbles; immersing the dried foam nickel substrate into the solution for 1min, taking out the catalyst, cleaning and drying for later use.

The scanning electron microscope of the catalyst prepared in this comparative example is shown in FIG. 16. The substrate of the catalyst is exposed in a large area, the successful loading of the catalyst is not seen, and the uniformity is poor.

The performance test method of the catalyst of this comparative example is the same as that of example 1.

Comparative example 2

The catalyst of this comparative example was prepared in the same manner as in example 1 except that the substrate size was 10 cm. Times.10 cm and the thickness was 1.0mm, and the metal salt solution was a nickel nitrate solution, which was 1000mL in amount, and 100mL of H was added at a mass fraction of 30% ₂ O ₂ And (3) preparing a suspension of the C solution together. After adding H ₂ O ₂ During the course of (2), the suspension of C liquid was not significantly changed.

And transferring the solution C into a glass container, performing short ultrasonic treatment, immersing the dried foam nickel substrate into the solution for 1min, taking out the catalyst, and cleaning and drying for later use.

The scanning electron microscope of the catalyst prepared in this comparative example is shown in FIG. 17. It can be seen that the catalyst was not successfully supported in large amounts and the substrate exposure was evident.

Comparative example 3

The catalyst of this comparative example was prepared in the same manner as in example 1 except that the substrate size was 10 cm. Times.10 cm and the thickness was 1.0mm, and the metal salt solution was a copper sulfate solution, which was 1000mL, and 100mL of H was added at a mass fraction of 30% ₂ O ₂ And (3) preparing a suspension of the C solution together. After adding H ₂ O ₂ In the process of (2), the suspension of the C solution is gradually changed into a bluish-green suspension, and a large amount of bluish-green precipitate is generated.

The scanning electron microscope image of the catalyst prepared in this comparative example is shown in FIG. 18. The catalyst has obvious exposure of the substrate, less catalyst load and no specific morphology.

Experimental example

1. Electric oxidation catalytic process performance

In this experimental example, the catalysts prepared by the methods described in examples 1 to 8 and comparative examples 1 to 3 were respectively subjected to an oxidation electrocatalytic process test using a 3-electrode system.

In the experimental example, a reference electrode is selected from Hg/HgO electrodes, wherein 1M KOH solution is filled in the Hg/HgO electrodes, a counter electrode is selected from a platinum net, and a working electrode is selected from a platinum clamp electrode; separating the H-type electrolytic cell 2 chambers by selecting a Nafion212 cation exchange membrane; the electrolyte is selected from electrolyte containing 50mM HMF+1MKOH.

In the experimental example, the test method selects a linear sweep voltammetry, the sweep voltage range of the linear sweep voltammetry is 0.2-0.8V (vs. Hg/HgO), the sweep rate is 2-10mV/s, and the number of the sweep turns is 1.

The catalyst was prepared according to the procedure and parameters of example 1 and 5 sets of replicates were run, and the LSV curves for HMFOR and OER for the oxidative electrocatalytic process for preparing the catalyst were shown in figure 9. As shown in the graph, the catalyst preparation method shows excellent reproducibility, and the difference of the catalyst performance of 5 groups of repeated tests is small.

The required catalysts were prepared according to the method and parameters of example 2, and other optimized samples with different molar ratios of nickel and copper metal ions were prepared respectively, and the LSV curves of HMFOR and OER of the prepared catalysts for the oxidation electro-catalysis process were shown in fig. 10. As a result, the catalyst having a molar ratio of nickel to copper metal ions of 3:1 exhibited the most excellent catalytic activity.

The required catalysts were prepared according to the procedure and parameters of example 3, and other samples with optimized total concentrations of different metal ions were prepared, respectively, and the LSV curves of HMFOR and OER for each group of prepared catalysts subjected to the oxidative electrocatalysis process were shown in fig. 11. As shown in the graph, the catalyst with the total concentration of metal ions of 400mM shows the most excellent catalytic activity, and the catalyst performance shows a "volcanic type" rule that the catalyst is increased firstly and then is decreased with the increasing concentration from 100mM to 600 mM.

The required catalysts were prepared according to the procedure and parameters of example 4 and samples were prepared at different impregnation times, respectively, and the LSV curves for HMFOR and OER for each set of catalysts subjected to the oxidative electrocatalysis process were shown in fig. 12. As a result, the catalyst activity gradually decreased with the increase of the impregnation time, and the catalyst having the shortest impregnation time exhibited the most excellent catalytic activity.

The LSV curves of HMFOR for the catalysts of the different substrates prepared in examples 5-7 (iron foam FF, cobalt foam CoF, copper foam CuF, carbon fiber paper CP) and the corresponding blank substrates were subjected to oxidative electrocatalytic processes, respectively, are shown in fig. 13. As shown in the figure, after the impregnation treatment, the activity of different substrates on catalyzing the oxidation of HMF is obviously improved after the active components are loaded, and the universality of the preparation method of the catalyst is high.

The desired catalyst was prepared according to the procedure and parameters described in example 8 and 5 sets of parallel runs were performed, and the LSV curves for HMFOR and OER for each set of catalysts subjected to the oxidative electrocatalytic process are shown in fig. 14. As shown in the graph, the catalyst preparation method shows excellent reproducibility in preparing large-size catalysts, and the difference of the catalytic performance of 5 groups of repeated tests is small.

The FDCA Faraday efficiency (FE,%) versus Yield plot (YIeld,%) for the HMFOR stability test of the catalyst oxidation electrocatalytic process of example 1 is shown in FIG. 15. As shown in the figure, the catalyst treated by the impregnation method has FDCA faraday efficiencies maintained above 95% and FDCA yields maintained above 91% in electrolysis for up to 18 cycles, and exhibits excellent stability.

The LSV curves for HMFOR for the catalytic oxidation electrocatalytic process for comparative examples 1-3 and example 1 are shown in FIG. 19. As a result, the catalysts described in comparative examples 1-3 exhibited significantly lower performance for catalyzing the oxidation of HMF than in example 1. This indicates that additional H is added to the precursor suspension ₂ O ₂ The method is not suitable for preparing large-size catalysts, has small and uneven active component loading, and poor process reproducibility, and cannot be well used for industrial production.

In conclusion, the catalyst prepared by the method has excellent catalytic activity and stability in catalyzing HMF oxidation, the method is suitable for various base materials, the method has high universality, and meanwhile, the large-size catalyst prepared by the method has good reproducibility and is easy to scale-up production.

2. Comparison of the preparation method and the Performance of the known catalyst

The characteristics of the catalyst prepared in example 1 of the present application are compared with those of a part of the reported synthesis process of the HMF oxidation electrocatalyst, as shown in Table 1 below.

Table 1 comparative characteristics of catalyst synthesis process

The characteristics of the catalyst prepared in example 1 of the present application are compared with those of the partially reported HMF oxidation electrocatalyst performance, see table 2 below, test method see experimental example 1.

Table 2 comparative characteristics of catalyst performance

Note that: a. current density at 1.45V (vs. rhe); b. current density at 1.40V (vs. rhe);

in summary, compared with the preparation method and performance comparison of the known catalyst, the total time required by the process for preparing the catalyst in the embodiment 1 of the application is obviously shortened from several hours to tens of seconds; the highest temperature required by the process is reduced from hundreds of common degrees centigrade to room temperature; in particular, the catalyst size is increased from a few square centimeters to hundreds of square centimeters, and the preparation method has the advantages of simple and quick operation, short synthesis time and easy preparation of large-size catalyst. Meanwhile, the catalyst shows excellent catalytic HMF oxidation performance, particularly stability obviously superior to that of a part of reported catalysts, and has potential for further industrialization.

It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the application.

Claims

1. The preparation method of the large-size 5-hydroxymethylfurfural oxidation electrocatalyst is characterized by comprising the following steps of:

2. The method for preparing the large-size 5-hydroxymethylfurfural oxidation electrocatalyst according to claim 1, wherein in step (1), the copper salt solution comprises a copper sulfate solution and/or a copper nitrate solution;

preferably, the concentration of the copper salt solution is 25-600mmol/L.

3. The method for preparing a large-size 5-hydroxymethylfurfural oxidation electrocatalyst according to claim 1 or 2, wherein in step (1), the nickel salt solution comprises a nickel nitrate solution and/or a nickel sulfate solution;

preferably, the concentration of the nickel salt solution is 25-600mmol/L.

4. A method for preparing a large-size 5-hydroxymethylfurfural oxidation electrocatalyst according to any one of claims 1 to 3, wherein in step (1), the metal salt solution comprises a mixed solution of a copper salt solution and a nickel salt solution;

in the metal salt solution, the molar ratio of nickel ions to copper ions is >0-4:4- >0;

5. The method for preparing the large-size 5-hydroxymethylfurfural oxidation electrocatalyst according to claim 4, wherein the step of mixing the metal salt solution comprises a step of adding the copper salt solution dropwise to the nickel salt solution;

preferably, the dripping time is controlled to be 5-20min.

6. The method for preparing a large-sized 5-hydroxymethylfurfural oxidation electrocatalyst according to any one of claims 1 to 5, wherein in step (2), the base material has a size of (1.5 to 10) cm× (1.5 to 10) cm and a thickness of 0.2 to 1.6mm;

7. The method for preparing a large-size 5-hydroxymethylfurfural oxidation electrocatalyst according to any one of claims 1 to 6, wherein the time of the impregnation treatment is 10s to 10min;

preferably, the pretreatment step includes the steps of oxidizing and cleaning the base material.

8. A large-size 5-hydroxymethylfurfural oxidation electrocatalyst prepared by the method of any one of claims 1 to 7;

preferably, the size of the 5-hydroxymethylfurfural oxidation electrocatalyst is (1.5-10) cm× (1.5-10) cm, and the thickness is 0.2-1.6mm.

9. The use of the large-size 5-hydroxymethylfurfural oxidation electrocatalyst according to claim 8 in a process for preparing FDCA by electrocatalytic oxidation of HMF.

10. A process for preparing FDCA by electrocatalytic oxidation of HMF, comprising the step of preparing FDCA by electrocatalytic oxidation of HMF as a starting material in the presence of the catalyst of claim 9.