WO2022227367A1

WO2022227367A1 - Preparation method and application of monolithic cobalt-doped nickel-molybdenum nanowire catalyst

Info

Publication number: WO2022227367A1
Application number: PCT/CN2021/116456
Authority: WO
Inventors: 谌春林; 夏博文; 张建
Original assignee: 中国科学院宁波材料技术与工程研究所
Priority date: 2021-04-30
Filing date: 2021-09-03
Publication date: 2022-11-03
Also published as: CN115261895A

Abstract

Disclosed in the present application a preparation method and application of a monolithic cobalt-doped nickel-molybdenum nanowire catalyst. The catalyst comprises a carrier and an active substance grown in situ on the carrier. The active material comprises cobalt, nickel, and molybdenum. The preparation method comprises: 1. generating a precursor on a carrier by means of a hydrothermal reaction; and 2. performing in-situ electrochemical activation on the precursor to obtain a monolithic cobalt-doped nickel-molybdenum nanowire catalyst. The monolithic cobalt-doped nickel-molybdenum nanowire catalyst provided by the present application is high in stability and long in service life, has rich pore structure and large-length-diameter ratio nanowire morphology, improves reaction mass transfer and load transfer rate. Compared with a nano-powder catalyst, the catalyst of the present application is easily separated from a product after reaction, and can be reused multiple times. The catalyst can be applied to the fields of chemical engineering, environmental protection, biomass conversion and the like, and is particularly suitable for electrocatalytic reaction of large-current biomass.

Description

Preparation method and application of a monolithic cobalt-doped nickel-molybdenum nanowire catalyst

technical field

The present application relates to a monolithic cobalt-doped nickel-molybdenum nanowire catalyst, a preparation method and application thereof, and belongs to the technical field of catalysis.

Background technique

At present, catalysts are widely used in chemical production to speed up the reaction rate and improve the selectivity of target products. Traditional precious metal catalysts such as gold, platinum, and ruthenium are expensive, which limits their large-scale industrial application. Transition metals such as nickel, cobalt, and molybdenum not only have good catalytic properties, but also have abundant reserves and low prices, and are expected to replace precious metal catalysts in the field of electrocatalysis. The performance of electrocatalysts largely depends on their geometry, active defects, and electronic band distribution. Through catalyst structure design and surface interface engineering, not only the mass transfer channel of the catalyst can be constructed, but also the electronic structure and band gap of the catalyst can be adjusted, thereby greatly improving the catalytic performance and prolonging the service life of the catalyst. Patent CN202010687438.7 discloses a noble metal/nickel-molybdenum-based composite hydrogen evolution electrocatalyst, which can realize the hydrogen evolution reaction of high current density, but the use of noble metal increases the use cost of the catalyst. Patent CN202010032065.X discloses a hydrogen evolution electrocatalyst with nickel molybdate-nickel nitride as the active component and nickel foam as the carrier, using a doping strategy and constructing a heterojunction to improve the conductivity and activity of the catalyst, but the preparation process involves high temperature The calcination and annealing step is cumbersome and low in controllability, which is not conducive to large-scale industrialization. The nickel-molybdenum-based catalysts currently involved have a single catalytic performance, which can only improve the hydrogen evolution reaction rate at the cathode. To improve the energy utilization efficiency of the electrolysis system, it is necessary to develop catalysts to improve the anode reaction rate. However, the use of multiple catalysts increases the cost of the electrolysis system. Therefore, obtaining multifunctional electrocatalysts with high activity, selectivity, and stability is of great significance for the industrial application of electrocatalytic reactions.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the present invention provides a preparation method and application of a monolithic cobalt-doped nickel-molybdenum nanowire bifunctional catalyst. Partial dissolution builds abundant pore channels, which provide more mass transfer channels for reaction molecules, and at the same time increase the specific surface area of electrocatalytic activity. Second, the doping containing the variable-valent metal cobalt can tune the electronic structure of the active site, improve the reaction activity and reduce the overpotential required for the electrocatalytic conversion of biomass. The monolithic catalyst has high catalytic activity, stable performance, simple preparation method and low cost.

The monolithic cobalt-doped nickel-molybdenum nanowire catalyst comprises a carrier and an active material grown on the carrier in situ;

The active material includes cobalt element, nickel element and molybdenum element.

In the catalyst, the content of cobalt element is 1-10wt%, the content of nickel element is 50-80wt%, and the content of molybdenum element is 10-30wt%

The content of each element is in terms of its mass percentage.

Optionally, the content of the cobalt element is independently selected from any value or any two of 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, and 10wt%. range between the values.

Optionally, the content of the nickel element is independently selected from any value of 50 wt %, 55 wt %, 60 wt %, 65 wt %, 70 wt %, 75 wt %, 80 wt %, or a range value between any two.

Optionally, the content of the molybdenum element is independently selected from any value of 10 wt %, 15 wt %, 20 wt %, 25 wt %, 30 wt %, or a range value between any two.

There is no particular limitation on the carrier in this application. In order to prepare a uniform catalyst and improve the catalytic efficiency, in order to satisfy the requirement that the carrier can be laid flat or stand sideways at the bottom of the reactor, optionally, the carrier is selected from foamed metal, carbon fiber cloth, sheet metal any of the .

Optionally, the active substance is in the shape of needle-like nanowires on the carrier.

Optionally, the nanowire has a diameter of 50-100 nm and a length of 200-800 nm.

According to yet another aspect of the present application, a method for preparing the monolithic cobalt-doped nickel-molybdenum nanowire catalyst is provided, the method at least comprising the following steps:

Step 1, hydrothermally react the mixture containing the cobalt source, the nickel source and the molybdenum source with the carrier to obtain a catalyst precursor;

Step 2, electrochemically activating the catalyst precursor to obtain the monolithic cobalt-doped nickel-molybdenum nanowire catalyst.

Optionally, the method further comprises pretreating the carrier.

Specifically, the carrier preprocessing method is:

The carrier is immersed in 0.1-2M hydrochloric acid for 10-30 minutes and ultrasonically cleaned with absolute ethanol and deionized water for 10-20 minutes after taking out to obtain a carrier with impurities removed.

Specifically, step 1 includes:

The cobalt source, the nickel source, the molybdenum source and the solvent are mixed uniformly, and a carrier is added to prepare a catalyst precursor through a hydrothermal reaction.

Optionally, the cobalt source is selected from at least one of cobalt nitrate hexahydrate, cobalt sulfate, cobalt chloride hexahydrate, and cobalt acetate tetrahydrate;

The nickel source is selected from at least one of nickel nitrate hexahydrate, nickel acetate tetrahydrate, nickel chloride hexahydrate, nickel sulfate hexahydrate;

The molybdenum source is selected from at least one of sodium molybdate dihydrate and ammonium molybdate tetrahydrate.

Specifically, in the embodiments of the present application, the cobalt source is selected from at least one of cobalt nitrate hexahydrate and cobalt chloride hexahydrate;

The nickel source is selected from at least one of nickel acetate tetrahydrate and nickel sulfate hexahydrate;

The molybdenum source is selected from at least one of nickel acetate tetrahydrate and nickel sulfate hexahydrate.

Optionally, in terms of the number of moles of each substance itself, in step 1, the molar ratio of the cobalt source to the nickel source in the mixture is 1:5-1:100, and the molar ratio of the molybdenum source to the nickel source is 1:5-1 :50.

Preferably, the molar ratio of the cobalt source to the nickel source in the mixture is 1:5-1:80, and the molar ratio of the molybdenum source to the nickel source is 1:5-1:20.

Specifically, in the mixture, the lower limit of the molar ratio of the cobalt source to the nickel source can be independently selected from 1:5, 1:10, 1:20, 1:30, 1:40, 1:50; the upper limit of the molar ratio of the cobalt source to the nickel source Can be independently selected from 1:60, 1:70, 1:80, 1:90, 1:100.

Specifically, in the mixture, the lower limit of the molar ratio of the molybdenum source and the nickel source can be independently selected from 1:5, 1:8, 1:10, 1:15, 1:20, 1:25; the upper limit of the molar ratio of the molybdenum source and the nickel source Can be independently selected from 1:30, 1:35, 1:40, 1:45, 1:50.

Optionally, in step 1, the mixture further includes a solvent;

In this application, the concentration of each substance in the mixture is not particularly limited. In order to prepare a cobalt-doped nickel-molybdenum nanowire catalyst with excellent performance, enhance the stability of the catalyst and improve the service life, in the mixture, the molar ratio of the cobalt source to the solvent is 1:2000-1:12000;

Preferably, the solvent includes water.

Specifically, the lower limit of the molar ratio of the cobalt source to the solvent can be independently selected from 1:2000, 1:3000, 1:4000, 1:5000, 1:6000; the upper limit of the molar ratio of the cobalt source to the solvent can be independently selected from 1:7000 , 1:8000, 1:9000, 1:10000, 1:12000.

Optionally, in step 1, the condition of the hydrothermal reaction is:

The reaction temperature is 110℃～200℃, and the reaction time is 2h～15h.

Preferably, the reaction temperature is 140°C to 160°C, and the reaction time is 10h to 15h.

Specifically, the lower limit of the reaction temperature can be independently selected from 110°C, 115°C, 120°C, 125°C, and 130°C; the upper limit of the reaction temperature can be independently selected from 140°C, 150°C, 160°C, 180°C, and 200°C.

Specifically, the lower limit of the reaction time can be independently selected from 2h, 3h, 4h, 5h, 6h; the lower limit of the reaction time can be independently selected from 8h, 10h, 12h, 14h, 15h.

Optionally, the step 2 includes:

In an electrolytic cell containing an alkaline solution, the catalyst precursor is used as an anode to perform in-situ electrochemical activation to obtain the monolithic cobalt-doped nickel-molybdenum nanowire catalyst.

Optionally, the alkaline solution is selected from at least one of sodium hydroxide and potassium hydroxide solution.

Optionally, in the alkaline solution, the concentration of hydroxide is 0.1M-3M.

Preferably, in the alkaline solution, the concentration of hydroxide is 0.5M-2M.

Preferably, in the alkaline solution, the concentration of hydroxide is 1M.

Optionally, in step 2, the condition of the electrochemical activation is:

The activation voltage is 0.8～2V, the activation current density is 1～100mA/cm ² , and the activation time is 1～30h.

Preferably, the activation voltage is 1-1.5V, the activation current density is 10-50 mA/cm ² , and the activation time is 2-5h.

In a specific embodiment, the electroactivation process is activated at a constant voltage until the current reaches a steady state or at a constant current density until the potential reaches a steady state.

Specifically, the lower limit of activation voltage can be independently selected from 0.8V, 0.9V, 1V, the upper limit of activation voltage can be independently selected from 1.5V, 1.6V, 1.7V, 1.8V, 1.9V, 2.0V; the lower limit of activation current density can be independently selected From 1mA/cm ² , 5mA/cm ² , 10mA/cm ² , 20mA/cm ² , 30mA/cm ² , the upper limit of activation current density can be independently selected from 50mA/cm ² , 60mA/cm ² , 70mA/cm ² , 90mA /cm ² , 100 mA/cm ² .

Specifically, the lower limit of activation time can be independently selected from 1h, 2h, 5h, 10h, 13h, and the upper limit of activation time can be independently selected from 15h, 17h, 20h, 25h, 30h.

Optionally, the method further comprises: washing and drying the catalyst precursor;

The drying conditions are as follows: the drying temperature is 50°C to 100°C, and the drying time is 5h to 12h.

A small amount of solid matter is attached to the surface of the precursor obtained by the reaction. In order to remove the solid matter, a washing operation is required. Preferably, the washing method is as follows: washing the precursor with water and ethanol successively 2-3 times.

After the catalyst precursor is washed, it is dried to remove the residual water and ethanol of the precursor.

Specifically, the lower limit of the drying temperature can be independently selected from 50°C, 55°C, 60°C, 65°C, and 70°C; the upper limit of the drying temperature can be independently selected from 75°C, 80°C, 85°C, 90°C, and 100°C.

Specifically, the drying time can be independently selected from 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, or any value between the above two points.

According to yet another aspect of the present application, an application of the monolithic cobalt-doped nickel-molybdenum nanowire catalyst is provided.

A preparation method of 2,5-furandicarboxylic acid, characterized in that the method at least comprises:

The solution containing the reaction substrate is reacted under the action of a catalyst to obtain 2,5-furandicarboxylic acid;

The reaction substrate is selected from 2,5-furandimethanol, 5-hydroxymethylfurfural, 2,5-furandicarbaldehyde, 5-hydroxymethyl-2-furancarboxylic acid, 5-formyl-2-furancarboxylic acid at least one of;

The catalyst is selected from at least one of the monolithic cobalt-doped nickel-molybdenum nanowire catalysts and the monolithic cobalt-doped nickel-molybdenum nanowire catalysts prepared by any of the above-mentioned methods.

Optionally, the method includes:

The 2,5-furandicarboxylic acid is obtained by carrying out an electrochemical reaction using the reaction substrate as a raw material and the catalyst as a working electrode.

Specifically, the method is:

Using the reaction substrate as a raw material, using the catalyst as a working electrode, a carbon rod as a counter electrode, mercury/mercury oxide as a reference electrode, and 1M KOH as an electrolyte to construct a reaction system, a constant voltage reaction was performed to obtain the 2,5 - Furandicarboxylic acid.

Optionally, the electrochemical reaction conditions are:

The reaction voltage is 1-3V, and the reaction time is 0.5-5h.

Specifically, the reaction voltage can be independently selected from 1V, 1.5V, 2V, 2.5V, 3V, or any value between the above two points.

Specifically, the reaction time can be independently selected from 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, or any value between the above two points.

The beneficial effects that this application can produce include:

1) The monolithic cobalt-doped nickel-molybdenum nanowire catalyst provided by the present application has high stability and long service life. During the preparation process, after the precursor is treated by simple electrochemical activation, the molybdenum element on the surface of the nanowire is partially dissolved to form abundant pores, which improves the specific surface area of electrocatalytic activity. Secondly, the nanowires obtained by structural design have a large aspect ratio structure, so they have better electronic conductivity and surface contact ability, improve the reaction mass transfer and charge transfer rate, and can achieve the large current density required in actual production. Require.

2) The preparation of the monolithic cobalt-doped nickel-molybdenum nanowire catalyst provided by the application only needs to pass the hydrothermal and electrochemical activation steps, and does not require subsequent high-temperature calcination treatment, thereby reducing the energy consumption for preparation; the raw materials are cheap and easily available, and the catalyst can be large-scale. preparation, and the equipment and technical requirements are low. Compared with nano-powder catalysts, it is easy to separate from products when used for catalytic reactions, and can be reused many times.

3) The monolithic cobalt-doped nickel-molybdenum nanowire catalyst provided in this application is used for anode electrocatalytic oxidation of 2,5-furandimethanol, 5-hydroxymethylfurfural, 2,5-furandicarbaldehyde, 5-hydroxymethyl The preparation of 2,5-furandicarboxylic acid from yl-2-furancarboxylic acid and 5-formyl-2-furancarboxylic acid has stable catalytic performance and good hydrogen evolution performance, so it can be used as a bifunctional catalyst for simultaneous biomass oxidation reaction and hydrogen evolution The reaction greatly improves the utilization efficiency of the input energy. In addition, the catalyst can be extended to other electrocatalytic reactions of organic small molecules.

Description of drawings

Fig. 1 is the scanning electron microscope image of monolithic cobalt-doped nickel-molybdenum nanowire catalyst precursor obtained in Example 1;

Fig. 2 is the scanning electron microscope image of monolithic cobalt-doped nickel-molybdenum nanowire catalyst obtained in Example 1;

Fig. 3 is the scanning electron microscope image of the catalyst precursor obtained in Example 1;

Fig. 4 is the scanning electron microscope image of the catalyst precursor obtained in Example 2;

Fig. 5 is the scanning electron microscope image of the catalyst precursor obtained in Example 3;

6 is a TEM image of the monolithic cobalt-doped nickel-molybdenum nanowire catalyst prepared in Example 1, wherein Figures a and b are TEM images under different magnifications;

Figure 7 is the polarization curve of the catalyst prepared in Example 1 as an electrocatalytic electrode in a solution containing 100 mM 2,5-furandimethanol and 1 M potassium hydroxide;

Fig. 8 is the high performance liquid chromatogram of each material in the reaction process of embodiment 8;

FIG. 9 is a graph showing the change of reactant conversion rate and product yield with time in the reaction of Example 8. FIG.

Detailed ways

The present application will be described in detail below with reference to the examples, but the present application is not limited to these examples.

The experimental methods used in the following examples are conventional methods unless otherwise specified; the reagents, materials, etc. used in the following examples can be obtained from commercial sources unless otherwise specified. For the instruments used in the following examples, unless otherwise specified, the parameters used in the use process are the parameters recommended by the manufacturer.

The instruments and parameters used in the sample characterization analysis in the examples are as follows:

SEM tests were performed at 8.0 kV using a HITACHI S-4800 scanning electron microscope.

SEM-EDX tests were performed at 20.0 kV using a HITACHI S-4800 scanning electron microscope.

TEM analysis was performed at 200 KV using a JEOL2100 transmission electron microscope.

Catalyst activation and catalytic reaction were performed using Chenhua CHI 760E electrochemical workstation.

Quantitative analysis of reactants, intermediates, and products was performed using Agilent high performance liquid chromatography.

Example 1

(1) Add 0.15g cobalt nitrate hexahydrate, 1.493g nickel acetate tetrahydrate, 1.235g ammonium molybdate tetrahydrate, and 60mL deionized water into a beaker, and stir magnetically for half an hour at room temperature to obtain a green uniform mixed solution.

(2) transfer the mixed solution prepared in step (1) into a 100mL hydrothermal reaction kettle, add two pieces of foamed nickel carriers with a size of 1cm*3cm, make it flat or stand on the bottom of the reaction kettle, put the reaction kettle in The reaction was carried out at 140 °C for 5 h in an oven. After the reaction was completed, it was cooled to room temperature naturally, and the precursor was taken out and washed with water and ethanol for 3 times in turn. The washed precursor was placed in a beaker and placed in an oven for drying at 60 °C for 12 h. . The precursors were characterized by SEM, and the results are shown in Figure 1.

(3) The precursor obtained in step (2) is used as the anode, the carbon rod is used as the cathode, the mercury/mercury oxide is used as the reference electrode, and the 1M potassium hydroxide is used as the electrolyte to form a three-electrode system. The precursor was immersed in the electrolyte for 1 cm ² , and activated at a constant current of 10 mA/cm ² for 2 h, to obtain a monolithic cobalt-doped nickel-molybdenum nanowire catalyst grown in situ on nickel foam, which is designated as sample 1.

The obtained catalyst was characterized by EDX. The results are shown in Table 1. The percentages of elements on the catalyst surface are Co (1.57At%), Mo (13.60At%), O (22.31At%), Ni (62.52At%) In summary, the results show that the cobalt-doped nickel-molybdenum-based catalyst was successfully obtained.

Table 1

Example 2

The specific operations of steps (1) and (2) are the same as in Example 1.

(3) The precursor obtained in step (2) is used as the anode, the carbon rod is used as the cathode, the mercury/mercury oxide is used as the reference electrode, and the 1M potassium hydroxide is used as the electrolyte to form a three-electrode system. The precursor was immersed in the electrolyte for 1 cm ² , and activated with a constant current of 10 mA/cm ² for 5 h to obtain the monolithic cobalt-doped nickel-molybdenum nanowire catalyst grown on the foamed nickel in situ, which is designated as sample 2.

Example 3

The specific operations of steps (1) and (2) are the same as in Example 1.

(3) The precursor obtained in step (2) is used as the anode, the carbon rod is used as the cathode, the mercury/mercury oxide is used as the reference electrode, and the 1M potassium hydroxide is used as the electrolyte to form a three-electrode system. The precursor was immersed in the electrolyte for 1 cm ^-2 , activated with a constant current of 10 mA/cm ² for 30 h, to obtain the monolithic cobalt-doped nickel-molybdenum nanowire catalyst grown in situ on the nickel foam, which is designated as sample 3.

Example 4

The specific operations of steps (1) and (2) are the same as in Example 1.

(3) The precursor obtained in step (2) is used as the anode, the carbon rod is used as the cathode, the mercury/mercury oxide is used as the reference electrode, and the 1M potassium hydroxide is used as the electrolyte to form a three-electrode system. The precursor was immersed in the electrolyte for 1 cm ² , and activated at a constant current for 5 h under the condition of 50 mA/cm ² , to obtain the monolithic cobalt-doped nickel-molybdenum nanowire catalyst grown on the foamed nickel in situ, denoted as sample 4.

Example 5

(1) Add 0.09438g cobalt chloride hexahydrate, 1.577g nickel sulfate hexahydrate, 0.24195g sodium molybdate dihydrate, and 60mL deionized water to a beaker, and stir magnetically for half an hour at room temperature to obtain a green uniform solution.

(2) transfer the mixed solution prepared in step (1) into a 100mL hydrothermal reaction kettle, add two pieces of foamed nickel carriers with a size of 1cm*3cm, make it flat or stand on the bottom of the reaction kettle, put the reaction kettle in The reaction was carried out at 140 °C for 5 h in an oven. After the reaction was completed, it was cooled to room temperature naturally, and the precursor was taken out and washed with water and ethanol for 3 times in turn. The washed precursor was placed in a beaker and placed in an oven for drying at 60 °C for 12 h. .

(3) The precursor obtained in step (2) is used as the anode, the carbon rod is used as the cathode, the mercury/mercury oxide is used as the reference electrode, and the 1M potassium hydroxide is used as the electrolyte to form a three-electrode system. The precursor was immersed in the electrolyte for 1 cm ² , and activated at a constant current of 10 mA/cm ² for 2 h to obtain a monolithic cobalt-doped nickel-molybdenum nanowire catalyst grown on nickel foam in situ, denoted as sample 5.

Example 6

The specific operations of steps (1) and (2) are the same as in Example 5.

(3) The precursor obtained in step (2) is used as the anode, the carbon rod is used as the cathode, the mercury/mercury oxide is used as the reference electrode, and the 1M potassium hydroxide is used as the electrolyte to form a three-electrode system. The precursor was immersed in the electrolyte for 1 cm ² , and activated at a constant current of 20 mA/cm ² for 1 h, to obtain a monolithic cobalt-doped nickel-molybdenum nanowire catalyst grown in situ on nickel foam, which is designated as sample 6.

Example 7

The specific operations of steps (1) and (2) are the same as in Example 5.

(3) The precursor obtained in step (2) is used as the anode, the carbon rod is used as the cathode, the mercury/mercury oxide is used as the reference electrode, and the 1M potassium hydroxide is used as the electrolyte to form a three-electrode system. The precursor was immersed in the electrolyte for 1 cm ² , and activated at a constant voltage for 2 hours at 1.5 V to obtain a monolithic cobalt-doped nickel-molybdenum nanowire catalyst grown in situ on nickel foam, denoted as sample 7.

Example 8 Sample Morphology Characterization

Typically, taking samples 1-3 as examples, SEM tests were performed on samples 1-3, and the morphology and integrity of the catalyst nanowires at different activation times were compared and analyzed. In Figure 3, a, b, and c are the catalysts of Examples 1-3, respectively. SEM image at 5000x magnification. Analysis by scanning electron microscope: First, by comparing the morphology of the catalyst precursor (shown in Figure 1) and the morphology of the catalyst (shown in Figure 2), it can be seen that compared with the catalyst precursor, the nanoparticle after galvanostatic activation The wire becomes rough, which increases the contact area with the substrate, which is favorable for diffusion and mass transfer. In addition, it can be seen from Figure 3, Figure 4, and Figure 5 that the morphology of the catalyst nanowires after 2h, 5h, and 30h activation is complete, which proves that the prepared monolithic catalyst has excellent stability.

The catalyst prepared in Example 1 was tested and analyzed by transmission electron microscope. The monolithic cobalt-doped nickel-molybdenum nanowire catalyst of sample 1 was placed in an ethanol solution, and the supernatant was taken and dropped on the microgrid after sonicating for 2 hours. As shown in a in Figure 6, the nanowires on the surface of the carrier in the selected region range in diameter from 50 to 100 nm and length from 200 to 800 nm.

Example 9 Electrocatalytic oxidation of 2,5-furandimethanol BHMF to prepare 2,5-furandicarboxylic acid FDCA

Using linear sweep voltammetry to judge the electrocatalytic oxidation performance of the catalyst of Example 1 on BHMF, as shown in Figure 7, the current density can reach 10 mA per square centimeter when the potential is only 1.32V, and when the potential reaches 1.65V, the current density can reach 400 mA per square centimeter, high current density can improve the reaction rate and greatly improve the conversion rate of 2,5-furandimethanol.

At the same time, the monolithic catalyst obtained in Example 1 was used as the working electrode, a three-electrode electrolysis system was formed with the carbon rod of the counter electrode and the reference electrode mercury/mercury oxide, and 5 mL of 1M KOH was used as the electrolyte. 10 mM 2,5-furandimethanol was electrocatalytically converted at a constant voltage of 1.474 V. FIG. 8 is a high-performance liquid chromatography detection and analysis diagram of each substance in the reaction process, and dual wavelengths (220 nm, 265 nm) are used to detect the reactants, intermediates and products. Under the condition of 220nm wavelength, the reactant BHMF has a peak at 6.3min; under the condition of 265nm wavelength, the product FDCA has a peak at 2.5min. As the electrolysis proceeded, the peak area of the reactant BHMF gradually decreased, and the peak area of the product FDCA gradually increased. According to the standard curve measured by the external standard method, the peak area was converted into the corresponding concentration of the substance, and the conversion rate or yield value of each substance in the reaction process was calculated. It can be seen that as the reaction proceeds, the raw material 2,5-furandimethanol gradually decreases, and the yield of the main product 2,5-furandicarboxylic acid gradually increases. After the final reaction for 0.91 h, the conversion rate of 2,5-furandimethanol can reach 100%, the yield of the target product 2,5-furandicarboxylic acid is 98.18%, and the Faradaic efficiency is 97.9%. It shows that the catalyst of the present application can realize complete conversion of reactants and a higher yield of target product. In addition, the faradaic efficiency of the cathodic hydrogen evolution reaction is close to 100%.

Example 10 Electrocatalytic oxidation of 5-hydroxymethylfurfural HMF to prepare 2,5-furandicarboxylic acid FDCA

The monolithic catalyst obtained in Example 1 was used as the working electrode, a three-electrode electrolysis system was formed with the carbon rod of the counter electrode and the reference electrode mercury/mercury oxide, and 5 mL of 1M KOH was used as the electrolyte. The electrocatalytic conversion of 20 mM 5-hydroxymethyl furfural at a constant voltage of 1.6 V for 1 h, the final conversion rate of 5-hydroxymethyl furfural can reach 99%, and the yield of 2,5-furandicarboxylic acid is 90%.

Example 11 Electrocatalytic oxidation of 5-hydroxymethyl-2-furancarboxylic acid HMFCA to prepare 2,5-furandicarboxylic acid FDCA

The monolithic catalyst obtained in Example 2 was used as the working electrode, a three-electrode electrolysis system was formed with the carbon rod of the counter electrode and the reference electrode mercury/mercury oxide, and 5 mL of 1M KOH was used as the electrolyte. Constant voltage 1.7V electrocatalytic conversion of 100mM 5-hydroxymethyl-2-furancarboxylic acid for 3h, the final conversion rate of 5-hydroxymethyl-2-furancarboxylic acid can reach 89%, and the yield of 2,5-furandicarboxylic acid is 82% .

Example 12 Electrocatalytic oxidation of 2,5-furandicarbaldehyde DFF to prepare 2,5-furandicarboxylic acid FDCA

The monolithic catalyst obtained in Example 3 was used as the working electrode, a three-electrode electrolysis system was formed with the carbon rod of the counter electrode and the reference electrode mercury/mercury oxide, and 5 mL of 1M KOH was used as the electrolyte. The electrocatalytic conversion of 100 mM 2,5-furandicarboxaldehyde was carried out at a constant voltage of 2V for 2 h, and the final conversion rate of 2,5-furandicarbaldehyde could reach 86%, and the yield of 2,5-furandicarboxylic acid was 80%.

Example 13 Electrocatalytic oxidation of 5-formyl-2-furancarboxylic acid FFCA to prepare 2,5-furandicarboxylic acid FDCA

The monolithic catalyst obtained in Example 3 was used as the working electrode, a three-electrode electrolysis system was formed with the carbon rod of the counter electrode and the reference electrode mercury/mercury oxide, and 5 mL of 1M KOH was used as the electrolyte. The electrocatalytic conversion of 200mM 5-formyl-2-furancarboxylic acid was carried out at a constant voltage of 1.8V for 1.5h, and the final conversion rate of 5-formyl-2-furancarboxylic acid could reach 89%, and the yield of 2,5-furandicarboxylic acid was 83%.

To sum up, the cobalt-doped nickel-molybdenum nanowire electrocatalyst provided by the present application has excellent stability and can meet the current density requirements for industrial production. Secondly, it can efficiently catalyze the conversion of 2,5-furandimethanol, 5-hydroxymethylfurfural, 2,5-furandicarbaldehyde, 5-hydroxymethyl-2-furancarboxylic acid, and 5-formyl-2-furancarboxylic acid to prepare 2,5-furandicarboxylic acid has broad application prospects in the field of biomass electrocatalytic conversion.

The above are only a few embodiments of the present application, and are not intended to limit the present application in any form. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Without departing from the scope of the technical solution of the present application, any changes or modifications made by using the technical content disclosed above are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

A monolithic cobalt-doped nickel-molybdenum nanowire catalyst, characterized in that the catalyst comprises a carrier and an active substance grown on the carrier in situ;

The active material includes cobalt element, nickel element and molybdenum element.
The monolithic cobalt-doped nickel-molybdenum nanowire catalyst according to claim 1, characterized in that, in the catalyst, the content of cobalt element is 1-10 wt%, the content of nickel element is 50-80 wt%, and the content of molybdenum element is 50-80 wt%. The content is 10-30wt%,

The content of each element is in terms of its mass percentage.
The monolithic cobalt-doped nickel-molybdenum nanowire catalyst according to claim 1, wherein the carrier is selected from any one of foam metal, carbon fiber cloth, and sheet metal.
The monolithic cobalt-doped nickel-molybdenum nanowire catalyst according to claim 3, wherein the active material is in the shape of nanowires on the carrier.
The preparation method of the monolithic cobalt-doped nickel-molybdenum nanowire catalyst according to any one of claims 1-4, wherein the method at least comprises the following steps:

Step 1, hydrothermally react the mixture containing the cobalt source, the nickel source, and the molybdenum source with the carrier to obtain a catalyst precursor;

Step 2, electrochemically activating the catalyst precursor to obtain the monolithic cobalt-doped nickel-molybdenum nanowire catalyst.
The preparation method according to claim 5, wherein in step 1, the cobalt source is selected from at least one of cobalt nitrate hexahydrate, cobalt sulfate, cobalt chloride hexahydrate, and cobalt acetate tetrahydrate;

The nickel source is selected from at least one of nickel nitrate hexahydrate, nickel acetate tetrahydrate, nickel chloride hexahydrate, and nickel sulfate hexahydrate;

The molybdenum source is selected from at least one of sodium molybdate dihydrate and ammonium molybdate tetrahydrate.
The preparation method according to claim 5, wherein, in step 1, the molar ratio of the cobalt source and the nickel source in the mixture is 1:5 to 1:100 in terms of the number of moles of each substance itself, and the molybdenum source and the The molar ratio of nickel source is 1:5～1:50.
The preparation method according to claim 5, wherein in step 1, the mixture further comprises a solvent;

In the mixture, the molar ratio of the cobalt source to the solvent is 1:2000-1:12000 in terms of the number of moles of the substance itself.
The preparation method according to claim 8, wherein the solvent comprises water.
preparation method according to claim 5, is characterized in that, in step 1, the condition of described hydrothermal reaction is:

The reaction temperature is 110℃～200℃, and the reaction time is 2h～15h.
The preparation method according to claim 5, wherein the step 2 comprises:

In an electrolytic cell containing an alkaline solution, the catalyst precursor is used as an anode to perform in-situ electrochemical activation to obtain the monolithic cobalt-doped nickel-molybdenum nanowire catalyst.
The preparation method according to claim 11, wherein the alkaline solution is selected from at least one of sodium hydroxide and potassium hydroxide solution.
The preparation method according to claim 11, wherein, in the alkaline solution, the concentration of the hydroxide is 0.1 mol/L to 3 mol/L.
preparation method according to claim 5, is characterized in that, described electrochemical activation condition is:

The activation voltage is selected to be 0.8-2V or the activation current density is selected to be 1-100mA/cm 2 , and the activation time is 1-20h.
A preparation method of 2,5-furandicarboxylic acid, characterized in that the method at least comprises:

The solution containing the reaction substrate is reacted under the action of a catalyst to obtain 2,5-furandicarboxylic acid;

The reaction substrate is selected from 2,5-furandimethanol, 5-hydroxymethylfurfural, 2,5-furandicarbaldehyde, 5-hydroxymethyl-2-furancarboxylic acid, 5-formyl-2-furancarboxylic acid at least one of;

The catalyst is selected from the monolithic cobalt-doped nickel-molybdenum nanowire catalyst according to any one of claims 1-4 and the monolithic cobalt-doped nickel-molybdenum nanowire prepared by the method according to any one of claims 5-14 at least one of the catalysts.
The preparation method of 2,5-furandicarboxylic acid according to claim 15, wherein the method comprises:

The 2,5-furandicarboxylic acid is obtained by using the reaction substrate as a raw material and the catalyst as a working electrode to carry out an electrochemical reaction.
The preparation method of 2,5-furandicarboxylic acid according to claim 16, wherein the electrochemical reaction conditions are:

The reaction voltage is 1.1-3V, and the reaction time is 0.5-5h.