CN113604822A

CN113604822A - Carbon/anthraquinone composite material, preparation method thereof and application thereof in hydrogen peroxide synthesis

Info

Publication number: CN113604822A
Application number: CN202110923759.7A
Authority: CN
Inventors: 丛燕青; 张恩泽; 陈闽
Original assignee: Zhejiang Gongshang University
Current assignee: Zhejiang Gongshang University
Priority date: 2021-08-12
Filing date: 2021-08-12
Publication date: 2021-11-05

Abstract

The invention discloses a preparation method of a carbon/anthraquinone composite material, which comprises the following steps: (1) modifying carbon material, regulating and controlling oxygen-rich active side position and defect position to obtain the product with rich O₂A modified carbon material which reduces the active site; (2) dissolving anthraquinone in an organic solvent, adding the modified carbon material obtained in the step (1), carrying out immobilization reaction, filtering and drying to obtain the modified carbon/anthraquinone composite material. The invention also comprises an application of the prepared carbon/anthraquinone composite material as an electrode in the electrocatalytic synthesis of hydrogen peroxide. Electrocatalytic reduction of O from air and water under mild conditions₂Generation of H₂O₂Realizing the miniaturization and high-efficiency production of hydrogen peroxideLarge-scale centralized mode of traditional production is removed, and H is realized₂O₂The hydrogen peroxide is prepared for use, is more green and convenient, and can meet the requirement on hydrogen peroxide in daily life.

Description

Carbon/anthraquinone composite material, preparation method thereof and application thereof in hydrogen peroxide synthesis

Technical Field

The invention relates to the technical field of electrocatalytic materials, in particular to a carbon/anthraquinone composite material, a preparation method thereof and application thereof in hydrogen peroxide synthesis.

Background

Hydrogen peroxide (H)₂O₂) Is one of the 100 most important chemicals in the world, and is used as an environment-friendly oxidant in paper/pulp industry,It has wide application in the fields of electronics, chemical synthesis, wastewater treatment, medical disinfection, etc.

The hydrogen peroxide solution is usually produced by an anthraquinone method, an electrolytic method, an oxygen cathode reduction method, an isopropyl alcohol method, a methylbenzyl alcohol oxidation method, or the like. Currently, 95% of H worldwide₂O₂The method is produced by an anthraquinone method with Pd as a catalyst, direct contact between oxygen and hydrogen does not exist in the reaction process, and the method is safe, however, the process flow is complex, the device investment is large, the energy consumption is high, the toxicity of the used organic solvent system is large, and the environmental pollution is serious. And, large scale H₂O₂The concentrated production requires additional transportation of hazardous materials, and the distillation with high energy consumption is commonly used to produce up to 70 wt% H₂O₂In order to minimize transportation costs. However, H₂O₂The hydrogen peroxide is unstable and easy to decompose, and the hydrogen peroxide can explode in closed environments such as transportation, so that the requirements of the storage and transportation processes of the hydrogen peroxide on the external environment are very high, and the storage and transportation costs are greatly increased. Thus, study of more green H₂O₂The in-situ synthesis technology realizes the use of hydrogen peroxide in the preparation, and is vital to reducing the storage and transportation cost and risk and improving the efficiency.

Production of H by electrochemical reduction of oxygen₂O₂The method is a continuous and dispersive hydrogen peroxide production method with great prospect, and the key point of the technology lies in preparing the high-efficiency and stable catalyst. The carbon material as an oxygen reduction electro-catalytic material with wide application has the characteristics of good conductivity, low price, easy obtainment, high efficiency, greenness, no pollution and the like, and can effectively catalyze O₂Two-electron or four-electron reduction occurs, and the method has very wide application in the field of electrochemistry. However, the carbon catalytic material also has the problems of low product selectivity and the like. To obtain a higher yield of hydrogen peroxide, O should be suppressed₂The four-electron reduction reaction of (2) promotes the two-electron reduction reaction for generating hydrogen peroxide.

Anthraquinone, as an important working fluid carrier in hydrogen peroxide production, can be repeatedly hydrogenated and oxidized, and reacts with hydrogen and oxygen respectively under certain pressure and temperature in the presence of a palladium catalyst to generate hydrogen peroxide.Anthraquinone as a catalytic medium shows certain superiority in the field of catalysis, can play roles in shortening industrial production time, reducing energy consumption and the like, and simultaneously has the advantages of good physical and chemical stability, low economic cost and the like. Anthraquinone as co-catalyst is cross-linked and bonded on carbon material and other solid phase carriers to form immobilized carbon/anthraquinone organic electro-catalyst, which is reasonably designed and precisely synthesized to obtain low-cost H with high activity and high selectivity₂O₂A catalyst.

Disclosure of Invention

The invention provides an immobilized carbon/anthraquinone organic electro-catalyst and a preparation method thereof, which can improve the electro-catalytic reduction O of the catalyst₂Generation of H₂O₂Selectivity and electrocatalytic efficiency of (1), achievement of H₂O₂In-situ, efficient and green generation, and the preparation of hydrogen peroxide is realized.

A preparation method of a carbon/anthraquinone composite material comprises the following steps:

step (1): modifying carbon material, regulating and controlling oxygen-rich active side position and defect position to obtain the product with rich O₂A modified carbon material which reduces the active site;

step (2): dissolving anthraquinone in an organic solvent, adding the modified carbon material obtained in the step (1), carrying out immobilization reaction, filtering and drying to obtain the modified carbon/anthraquinone composite material.

In the preparation route, the specific process conditions of the steps are as follows:

step (one) is as follows:

the carbon material may be a conjugated carbon material (g-C) having an anthraquinone-like structure₃N₄Modified graphene and carbon nanotubes), conductive carbon black, graphite powder, and the like.

The modification method is at least one of plasma modification, acid washing, ultrasonic treatment, gas phase treatment and calcination.

(II) in the step (2):

the anthraquinone may be 2-alkylanthraquinone, 2-aminoanthraquinone or 2-carboxyanthraquinone, etc. Preferably, the anthraquinone is 2-aminoanthraquinone.

The immobilization reaction may be a self-assembly reaction, a chemical bond bonding, or the like.

The organic solvent can be acetonitrile or ethanol, etc. Preferably, the organic solvent is an acetonitrile solution.

Preferably, the ratio of anthraquinone to modified carbon material in the step is 0.1-1: 1, the mass ratio of the anthraquinone to the organic solvent is 0.2-1: 1; further preferably, the ratio of anthraquinone to modified carbon material is 0.5: 1, the volume ratio of the mass of the anthraquinone to the organic solvent is 0.7: 1.

preferably, the drying in the step needs vacuum drying at 40-100 ℃, and the drying time is 1-24 h; further preferably, the drying in the step needs vacuum drying at 50-80 ℃, and the drying time is 2-5 h; most preferably, the vacuum drying temperature is 60 ℃ and the drying time is 3 h.

The modified carbon/anthraquinone composite material prepared by the preparation method has rich O₂The active sites are reduced, so that the hydrogen peroxide generated by the 2-electron reduction reaction of oxygen has higher selectivity and Faraday efficiency, and can be applied to the production of hydrogen peroxide by electrocatalysis.

The invention also comprises the application of the prepared carbon/anthraquinone composite material as an electrode in the electrocatalytic reduction of O₂Application in the synthesis of hydrogen peroxide.

Preferably, the application comprises the steps of:

and adding a binder into the obtained modified carbon/anthraquinone composite material to prepare a gas diffusion electrode, or loading the modified carbon/anthraquinone composite material on the surface of a conductive substrate by methods such as electrodeposition, drop coating and the like, and airing overnight. The prepared electrode is placed in acidic NO₂ ^-Soaking in solution, washing with water, vacuum drying to obtain modified carbon/anthraquinone composite electrode, and using it as working electrode for electrocatalytic reduction of O₂Preparing hydrogen peroxide.

Further preferably, the binder of this step may be polytetrafluoroethylene; the conductive substrate may be nickel foam, graphite, conductive glass (FTO), copper foam, carbon paper, carbon felt, carbon fiber, or the like.

Further preferably, acidic NO as defined in this step₂ ^-The solution can be adjusted in pH by hydrochloric acid or sulfuric acid, NaNO₂Or KNO₂Etc. supply NO₂ ^-；

Further preferably, the acidic NO in this step₂ ^-H in solution⁺Concentration of 0.1mol/L to 1.0mol/L, NO₂ ^-The concentration is 5mmol/L-50mmol/L, and the soaking time is 5min-60 min;

further preferably, the water in the step is distilled water or deionized water, the temperature of vacuum drying is 40-100 ℃, and the drying time is 1-6 h; most preferably, the temperature of vacuum drying is 60 ℃ and the drying time is 3 h.

Further preferably, O is electrocatalytically reduced₂The preparation of hydrogen peroxide needs to be carried out in an oxygen-enriched solution with the electrolyte concentration of 0.01-1mol/L, wherein a carbon/anthraquinone composite electrode is a cathode, a graphite flake or dimensionally stable metal oxide electrode is an anode, electrochemical reaction is carried out in the oxygen-enriched solution, and 1-5V working voltage is applied between the anode and the cathode.

In the preparation method, the thickness of the catalyst film layer of the carbon/anthraquinone composite electrode is regulated and controlled by adjusting the concentration of the anthraquinone reagent, controlling the content of the carbon material and the anthraquinone, adjusting the load capacity of the carbon/anthraquinone composite material and the like, so that the carbon/anthraquinone composite electrode material with proper and stable thickness is obtained, and the H pair of the carbon/anthraquinone composite electrode material is improved₂O₂The generated selectivity achieves the aims of improving the Faraday efficiency and reducing the energy consumption.

The carbon has a certain catalytic performance and also has good conductive performance, and provides sufficient electrons for the catalytic reaction of the anthraquinone; anthraquinone pair H₂O₂With high selectivity, the synergistic effect between anthraquinone and carbon materials makes the electro-catalytic reduction of O₂Synthesis of H₂O₂The reaction is more effective, and high catalytic efficiency which cannot be realized by a single catalytic material is obtained.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention selects the organic catalyst anthraquinone, the anthraquinone is immobilized on the solid phase carriers such as carbon materials, etc. to form the immobilized carbon/anthraquinone organic electro-catalyst, and the high-efficiency selective synthesis of the hydrogen peroxide is realized by electrochemically activating the anthraquinone organic catalyst.

(2) The method can retain the whole characteristics of complete anthraquinone organic catalysis by chemical bond bonding and other immobilization technologies, can not cause economic cost increase and environmental damage due to loss of the anthraquinone organic catalysis, does not need a subsequent anthraquinone purification process in the conventional anthraquinone method hydrogen peroxide preparation process, and is simple to operate, low in cost, more economic and efficient.

(3) The modified carbon/anthraquinone composite electrode prepared by the invention solves the problems of small specific surface area, slow charge transfer and the like of the traditional carbon-based electrode through microstructure adjustment, shows obvious electrocatalysis performance, and improves the selectivity of the electrode on hydrogen peroxide catalysis by fixing anthraquinone on a carbon-based material.

(4) Electrocatalytic reduction of O from air and water under mild conditions₂Generation of H₂O₂The method realizes the miniaturization and high-efficiency production of hydrogen peroxide, gets rid of the large-scale centralized mode of the traditional production, can completely obtain products with different controllable concentrations in the continuous electrosynthesis process, and realizes H₂O₂The hydrogen peroxide is prepared for use, is more green and convenient, and can meet the large demand of hydrogen peroxide in daily life.

Drawings

FIG. 1 shows that the carbon/anthraquinone composite catalytic electrode (AQ-C-Ni electrode), the carbon electrode (C-Ni electrode) and the foam nickel substrate electrode (Ni electrode) prepared on the foam nickel substrate are catalyzed to generate H in 0.1M electrolyte solution₂O₂A rate comparison graph of (a);

FIG. 2 is a graph showing the AQ-C-Ni electrodes prepared in example 1 catalyzing the generation of H under different pH conditions₂O₂Velocity versus velocity plot of (c).

Fig. 3 is a graph showing comparison of scanning CV curves of AQ-C-Ni electrodes prepared in example 1 at pH 3, pH 6 and pH 11.

Detailed Description

The invention will be described in detail with reference to the accompanying drawings and specific examples.

Example 1

In this example, a carbon (C) and Anthraquinone (AQ) composite material is prepared and loaded on a foamed nickel conductive substrate to construct a carbon/anthraquinone composite electrode (AQ-C-Ni electrode), which includes the following steps:

(1): selecting conductive carbon black as a carbon material, weighing 200mg of conductive carbon black, cleaning with distilled water, and performing plasma modification treatment. Fixing 2-aminoanthraquinone on conductive carbon black by using a self-assembly mode, dissolving 100mg of 2-aminoanthraquinone in 150mL of acetonitrile, adding 200mg of modified conductive carbon black after complete dissolution, standing for self-assembly reaction for 12h, and drying the powder obtained after vacuum filtration at 60 ℃ for 3h under a vacuum condition.

(2): and sequentially soaking the foamed nickel substrate in hydrochloric acid, absolute ethyl alcohol and deionized water, performing ultrasonic treatment for 15min, and airing in a shade. Weighing 170mg of the immobilized conductive carbon black/2-aminoanthraquinone powder obtained in the step (1), mixing with a small amount of absolute ethyl alcohol, adding polytetrafluoroethylene emulsion as a binder, carrying out ultrasonic treatment on the mixed solution for 15min to form paste, coating the paste on a foamed nickel substrate, and airing the foamed nickel substrate in a cool and dry place. Subjecting the obtained electrode to acidic NO₂ ^-Soaking in the solution for 20min, washing with deionized water, and vacuum drying at 60 deg.C for 3 hr to obtain the desired AQ-C-Ni electrode.

(3): build H₂O₂The generation device takes the AQ-C-Ni electrode prepared in the step (2) as a cathode, a graphite flake as an anode and is prepared with NaSO with the concentration of 0.1M₄Electrolyte solution, O was introduced before the start of the test₂The duration was 30min to bring the solution to oxygen saturation. Application of an operating voltage of 2.0V between the cathode and anode began to generate H₂O₂Reacting, continuously introducing O in the whole reaction process₂To maintain the oxygen concentration in the solution.

Comparative example 1

This example prepares a modified carbon (C) composite and supports it on a foamed nickel conductive substrate to construct a carbon electrode (C-Ni electrode). A C-Ni electrode was prepared in the same manner as described above except that 100mg of 2-aminoanthraquinone and 150mL of acetonitrile in step (1) of example 1 were removed. The method comprises the following specific steps:

(1): weighing 200mg of conductive carbon black, cleaning with distilled water, performing plasma modification treatment, and vacuum-filtering to obtain powder, and drying the powder for 3 hours at 60 ℃ under a vacuum condition.

(2): and sequentially soaking the foamed nickel substrate in hydrochloric acid, absolute ethyl alcohol and deionized water, performing ultrasonic treatment for 15min, and airing in a shade. Weighing 170mg of the modified conductive carbon black powder obtained in the step (1), mixing with a small amount of absolute ethyl alcohol, adding polytetrafluoroethylene emulsion as a binder, carrying out ultrasonic treatment on the mixed solution for 15min to form paste, coating the paste on a foamed nickel substrate, and airing the foamed nickel substrate in a cool and dry place. Subjecting the obtained electrode to acidic NO₂ ^-Soaking in the solution for 20min, washing with deionized water, and vacuum drying at 60 deg.C for 3 hr to obtain the desired C-Ni electrode.

FIG. 1 is a graph showing the AQ-C-Ni electrode obtained in example 1, the C-Ni electrode obtained in comparative example 1, and a foamed nickel base electrode (Ni electrode) used in example 1 and comparative example 1 for catalytically producing H in a 0.1M electrolyte solution₂O₂Velocity versus velocity plot of (c). As can be seen from FIG. 1, the AQ-C-Ni electrode catalyzes the production of H in a 0.1M electrolyte solution₂O₂The performance of the electrode is obviously superior to that of a C-Ni electrode and a Ni electrode, and the AQ-C-Ni electrode generates H at 30min₂O₂0.75mg, while the C-Ni electrode and the Ni electrode respectively generate 0.25mg and 0.05mg, which proves that the anthraquinone is fixed on the surface of the carbon material and has good catalytic activity, the anthraquinone and the carbon are not simply mixed, the combination of the anthraquinone and the carbon has synergistic catalytic action, and the effect of '1 +1 is more than 2' is achieved.

FIG. 2 is a graph showing the AQ-C-Ni electrodes prepared in example 1 catalyzing the generation of H under different pH conditions₂O₂From the graph of the rate comparison, it can be seen from fig. 2 that the AQ-C-Ni electrode has the highest catalytic efficiency at pH 6, and the catalytic efficiency is higher under alkaline conditions than under acidic conditions.

Fig. 3 is a graph showing comparison of scanning CV curves of AQ-C-Ni electrodes prepared in example 1 at pH 3, pH 6 and pH 11. Scanning the C-V curve comprises the steps of: the preparation concentration is 0.1M NaSO₄ElectrolyteSolution, O was introduced before the start of the test₂The duration was 30min to bring the solution to oxygen saturation. A three-electrode system is adopted for CV scanning to test the performance of the catalytic material, the AQ-C-Ni electrode prepared in the example 1 is taken as a working electrode, a graphite sheet is taken as a counter electrode, and an Ag/AgCl electrode is taken as a reference electrode; setting the scanning range of the CV of the workstation to be 0.1-1.6V and the scanning speed to be 0.02V/s, and continuously introducing O in the scanning process₂So as to keep the reaction conditions unchanged. As can be seen from FIG. 3, the AQ-C-Ni electrode catalytically synthesizes H under neutral and alkaline conditions₂O₂Compared with the catalytic efficiency under the acidic condition, the catalytic efficiency is higher.

Example 2

The procedure of example 1 was repeated except that in the process of preparing the AQ-C-Ni electrode, g-C was selected in step (1)₃N₄The carbon material was the same as in example 1.

The AQ-C-Ni electrodes prepared under the conditions of this example had slightly higher electrochemical performance than the electrodes prepared under the conditions of example 1, which uses g-C as the carbon material relative to conductive carbon black₃N₄AQ-C-Ni electrode prepared from carbon material generates H30 min₂O₂1.0mg。

Example 3

The procedure of example 1 was repeated except that in the preparation of the AQ-C-Ni electrode, 2-alkylanthraquinone was selected as the anthraquinone material in step (2), and the rest was the same as in example 1.

The AQ-C-Ni electrode prepared under the conditions of this example had slightly lower electrochemical performance than the electrode prepared under the conditions of example 1, and the AQ-C-Ni electrode prepared using 2-alkylanthraquinone as anthraquinone material produced H30 min, relative to 2-aminoanthraquinone₂O₂0.5mg。

Example 4

The procedure of example 1 was repeated except that in the preparation of the AQ-C-Ni electrode, in step (1), acid washing modification was used instead of plasma modification, as in example 1.

The AQ-C-Ni electrodes prepared under the conditions of this example had good electrochemical performance ratiosThe electrode prepared under the conditions of example 1 is slightly lower, and the AQ-C-Ni electrode prepared in the example generates H within 30min₂O₂0.7mg。

Example 5

The operational procedure of example 1 was repeated except that in the preparation of the AQ-C-Ni electrode, the mass ratio of 2-aminoanthraquinone to conductive carbon black in step (2) was changed to 0.3: 1, the rest of the same procedure as in example 1.

The AQ-C-Ni electrode prepared under the conditions of this example had slightly lower electrochemical performance than the electrode prepared under the conditions of example 1, and generated H30 min₂O₂0.65mg。

Example 6

The operational procedure of example 1 was repeated except that the operating voltage applied between the cathode and the anode was changed to 1.5V in step (3) in the process of preparing the AQ-C-Ni electrode, which was otherwise the same as in example 1.

The AQ-C-Ni electrode prepared under the conditions of this example had slightly lower electrochemical performance than the electrode prepared under the conditions of example 1, and generated H30 min₂O₂0.4mg。

Example 7

The procedure of example 1 was repeated except that in the process of preparing the AQ-C-Ni electrode, the fixed conductive carbon black/2-aminoanthraquinone powder was supported on the foamed nickel substrate by electrodeposition method without adding the polytetrafluoroethylene emulsion as a binder in step (2), and the rest was the same as in example 1.

The AQ-C-Ni electrode prepared under the conditions of this example has slightly higher electrochemical performance than the electrode prepared under the conditions of example 1, and generates H30 min₂O₂0.8mg。

Example 8

The operation of example 1 was repeated except that in the process of preparing the AQ-C-Ni electrode, in step (2), a conductive glass (FTO) was used as a substrate instead of the nickel foam, and the rest was the same as in example 1.

A prepared under the conditions of this exampleThe electrochemical performance of the Q-C-Ni electrode is slightly lower than that of the electrode prepared under the conditions of example 1, and the AQ-C-Ni electrode prepared in the example generates H within 30min₂O₂0.55mg。

The embodiment shows that the carbon/anthraquinone composite electrode prepared by the invention has excellent performance of synthesizing hydrogen peroxide.

The above-mentioned embodiments are intended to illustrate the technical solutions and advantages of the present invention, and it should be understood that the above-mentioned embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention, and any modifications, additions, equivalents, etc. made within the scope of the principles of the present invention should be included in the scope of the present invention.

Claims

1. The preparation method of the carbon/anthraquinone composite material is characterized by comprising the following steps:

(1) modifying carbon material, regulating and controlling oxygen-rich active side position and defect position to obtain the product with rich O₂A modified carbon material which reduces the active site;

(2) dissolving anthraquinone in an organic solvent, adding the modified carbon material obtained in the step (1), carrying out immobilization reaction, filtering and drying to obtain the modified carbon/anthraquinone composite material.

2. The method of producing a carbon/anthraquinone composite material according to claim 1, wherein in the step (1), the carbon material may be a conjugated carbon material (g-C) having an anthraquinone-like structure₃N₄Modified graphene and carbon nanotubes), conductive carbon black, graphite powder.

3. The method for preparing a carbon/anthraquinone composite material according to claim 1, wherein in the step (1), the modification method is at least one of plasma modification, acid washing, ultrasonic treatment, gas phase treatment and calcination.

4. The method for producing a carbon/anthraquinone composite material according to claim 1, wherein in the step (2), the anthraquinone may be 2-alkylanthraquinone, 2-aminoanthraquinone or 2-carboxyanthraquinone.

5. The method for preparing a carbon/anthraquinone composite material according to claim 1, wherein in the step (2), the immobilization reaction may be a self-assembly reaction or a chemical bonding.

6. The method for preparing a carbon/anthraquinone composite material according to claim 1, wherein in the step (2), the ratio of the anthraquinone to the modified carbon material is 0.1-1: 1, the drying temperature is 40-100 ℃.

7. A carbon/anthraquinone composite material characterized by being prepared by the preparation method of any one of claims 1 to 6.

8. A carbon/anthraquinone composite material as claimed in claim 7 as an electrode in electrocatalytic reduction of O₂The application of the synthetic hydrogen peroxide is characterized by comprising the following steps:

9. Use according to claim 8, wherein the binder is polytetrafluoroethylene and the conductive substrate is nickel foam, graphite, conductive glass, copper foam, carbon paper, carbon felt or carbon fibre.

10. Use according to claim 8, wherein said acidic NO is₂ ^-H in solution⁺Concentration of 0.1mol/L to 1.0mol/L, NO₂ ^-The concentration is 5mmol/L-50mmalcohol/L, and the soaking time is 5min-60 min.