CN111482175A - Preparation method of copper/cuprous oxide heterojunction nanosheet catalyst - Google Patents

Abstract

The invention provides a preparation method of a copper/cuprous oxide heterojunction nanosheet catalyst, wherein the copper/cuprous oxide heterojunction nanosheet catalyst is composed of copper and cuprous oxide. In the present invention, the traditional copper catalyst is modified by selecting cuprous oxide as a new auxiliary agent, and the catalytic activity of copper is greatly increased by forming a heterojunction with copper. In the present invention, the morphology of the catalyst is limited to nanosheets by the hydrothermal synthesis method, which increases the specific surface area, and at the same time, the molar ratio of copper/cuprous oxide can be adjusted by adjusting the feeding composition, and the catalysis of the catalyst can be effectively regulated. active.

Description

A kind of preparation method of copper/cuprous oxide heterojunction nanosheet catalyst

technical field

The invention relates to a preparation method of a copper/cuprous oxide heterojunction nanosheet catalyst, which belongs to the field of inorganic material preparation.

Background technique

Since the beginning of the 21st century, the development of the economy and the improvement of people's living standards have increased the demand for traditional fossil energy such as oil and coal, resulting in a large amount of greenhouse gas emissions such as carbon dioxide, and the content of carbon dioxide in the atmosphere. It is increasingly obvious that the human living environment is deteriorating day by day. Therefore, the resource utilization of carbon dioxide and the development of carbon dioxide green utilization technology have become the focus of research. Although carbon dioxide is a greenhouse gas, it is also a cheap, clean and effective carbon resource; if it can be used effectively, it can not only solve related environmental problems, but also reduce the dependence on other types of carbon resources.

As a simple low-molecular-weight organic carbonate, dimethyl carbonate has interesting properties such as stable chemical properties and non-toxicity to organisms, making it widely used as a green reagent in the chemical industry. There are many methods for synthesizing dimethyl carbonate in industry, such as methanol phosgenation, methanol oxidative carbonylation, ethylene carbonate and methanol transesterification, etc. Due to the serious pollution of raw materials, low product conversion rate and weak principle, these methods are greatly limited in practical application. The direct use of methanol and carbon dioxide to synthesize dimethyl carbonate also greatly increases the synthesis cost and equipment maintenance cost because the traditional copper-based catalyst requires high temperature and high pressure catalytic conditions. Therefore, it is urgent to find a catalyst that can be applied to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide at low temperature and low pressure.

As an emerging class of nanomaterials, 2D crystals exhibit unique physical properties and promising electronic properties due to their ultra-thin thickness and 2D morphology. This provides numerous opportunities for their wide-ranging applications across biology, medicine, physics and chemistry. Compared with bulk materials, two-dimensional materials not only have a large increase in specific surface area, but also exhibit completely different properties from bulk materials due to the confinement effect of two-dimensional materials. Compared with bulk materials, 2D materials are more likely to expose heterojunctions, and the existence of heterojunctions can lead to charge accumulation, enhance the adsorption of reactants, reduce the reaction activation energy, and effectively improve the yield.

In the present invention, a two-dimensional structure and a heterojunction-containing copper/cuprous oxide catalyst are synthesized by a hydrothermal method, and its special structure can effectively reduce the temperature and pressure required for the reaction, and greatly improve the yield. The process is simple, low in energy consumption, high in atomic utilization rate, and environmentally friendly, and is suitable for large-scale popularization and use.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for preparing a novel copper/cuprous oxide heterojunction nanosheet catalyst for the deficiencies of the prior art.

In order to achieve the above purpose of the invention, the present invention provides a preparation method of a copper/cuprous oxide heterojunction nanosheet catalyst, which comprises the following steps:

Step 1. Add the organic solvent to the alcohol solvent and stir to obtain a mixed solution;

Step 2. adding copper acetylacetonate and surfactant into the mixed solution, stirring vigorously to obtain a reaction solution;

Step 3. Transfer the reaction solution to a polytetrafluoroethylene reaction kettle, and after sealing, heat up to 100-200° C. to obtain a product;

Step 4. Washing, drying and grinding the product to obtain the copper/cuprous oxide heterojunction nanosheet catalyst.

In some embodiments, in step 1, the organic solvent is selected from N,N-dimethylformamide, N-methylpyrrolidone and derivatives thereof, or any combination thereof.

In some embodiments, in step 1, the alcohol solvent is selected from C _1-6 alcohols, preferably methanol, ethanol and derivatives thereof or any combination thereof.

In some embodiments, in step 1, the volume ratio of the alcohol solvent to the organic solvent is 1:1-6:1.

In some embodiments, in step 1, a magnetic stirrer is used for stirring at a rotational speed of 1000-4000 r/min for 10 minutes to 1 hour.

In some embodiments, in step 2, the surfactant is cetyltrimethylammonium bromide, dodecyltrimethylammonium bromide, polyvinylpyrrolidone, sodium oleate, or any combination thereof.

In some embodiments, in step 2, the molar ratio of copper acetylacetonate to surfactant is from 6:1 to 8:1.

In some embodiments, in step 2, a magnetic stirrer is used for stirring, and the rotation speed is 1000-4000 r/min, and the time is 10 minutes to 1 hour.

In some embodiments, in step 3, the volume ratio of the reaction solution to the volume of the polytetrafluoroethylene reactor is 1:2-1:4.

In some embodiments, in step 3, the temperature increase is programmed to the reaction temperature; preferably, the temperature increase rate is 5-10° C./min; preferably, the reaction time is 6-12 hours.

In some embodiments, in step 4, the washing is washing with deionized water until the pH of the supernatant is 7, and then washing with absolute ethanol twice.

In some embodiments, in step 4, the drying is a treatment at 60-80°C for 8-24 hours.

The present invention also provides the copper/cuprous oxide heterojunction nanosheet catalyst prepared by the above method.

The present invention provides the following beneficial effects:

The method provided by the invention can synthesize copper/cuprous oxide heterojunction nanosheet catalyst with nanoscale thickness under the condition of lower energy consumption. The prepared samples have good dispersibility, and the catalytic performance is higher than that of the existing catalysts. Furthermore, the introduction of the heterojunction can effectively improve the photoresponse ability of the sample, improve the practical value of the material, and have huge economic benefits.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of embodiments taken in conjunction with the accompanying drawings, wherein:

Figure 1 shows a high-resolution transmission electron microscope image of the product of Example 1;

Figure 2 shows a transmission electron microscope image of the product of Example 2;

FIG. 3 shows a transmission electron microscope image of the product of Example 3. FIG.

Figure 4 shows a transmission electron microscope image of the product of Example 4; and

FIG. 5 shows an X-ray electron diffraction (XRD) analysis pattern of the product of Example 4. FIG.

Detailed ways

Embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary and are only used to explain the present invention, but not to be construed as a limitation of the present invention.

Example 1

A preparation method of a copper/cuprous oxide heterojunction nanosheet catalyst adopts the following steps:

(1) 5mL of N,N-dimethylformamide was added to 30mL of ethanol, magnetic stirring, wherein the rotating speed was 4000r/min, to obtain a mixed solution of ethanol and N,N-dimethylformamide;

(2) the copper acetylacetonate of 8mmol and the hexadecyl trimethyl ammonium bromide of 1mmol are added in the mixed solution of step 1, with the rotating speed magnetic stirring of 4000r/min 0.5 hour, obtain reaction solution;

(3) the reaction solution of step 2 is transferred to the 140mL polytetrafluoroethylene reactor, after sealing, the temperature is programmed to 200°C, the temperature increase rate is 10°C/min, and the reaction is performed for 8 hours to obtain the product;

(4) Washing three times with water and ethanol, drying in an oven at 60° C. for 24 hours, and placing the dried product in a mortar to grind and disperse to obtain a copper/cuprous oxide heterojunction nanosheet catalyst.

The high-resolution transmission electron microscope image of the obtained powder is shown in Figure 1. It can be seen that the obtained copper/cuprous oxide heterojunction nanosheet catalyst shows two different lattice spacings, indicating that the obtained sample has high purity and accurate synthesis.

Example 2

A preparation method of a copper/cuprous oxide heterojunction nanosheet catalyst adopts the following steps:

(1) 15mL of N,N-dimethylformamide was added to 15mL of ethanol, magnetic stirring, wherein the rotating speed was 1000r/min, to obtain a mixed solution of ethanol and N,N-dimethylformamide;

(2) the copper acetylacetonate of 6mmol and the hexadecyl trimethyl ammonium bromide of 1mmol are added in the mixed solution of step 1, magnetic stirring 1 hour with the rotating speed of 1000r/min, obtains reaction solution;

(3) the reaction solution of step 2 is transferred to the polytetrafluoroethylene reactor of 60 mL, after sealing, the temperature is programmed to 100 ° C, the temperature increase rate is 5 ° C/min, and the reaction is performed for 8 hours to obtain the product;

(4) Washing three times with water and ethanol, drying in an oven at 60° C. for 24 hours, and placing the dried product in a mortar to grind and disperse to obtain a copper/cuprous oxide heterojunction nanosheet catalyst.

The topography (transmission electron microscope) of the obtained powder is shown in FIG. 2 . It can be seen that the obtained copper/cuprous oxide heterojunction nanosheet catalyst has only one morphology, which is nanosheet.

Example 3

A preparation method of a copper/cuprous oxide heterojunction nanosheet catalyst adopts the following steps:

(1) 10mL of N,N-dimethylformamide was added to 30mL of ethanol, magnetic stirring, wherein the rotating speed was 3000r/min, to obtain a mixed solution of ethanol and N,N-dimethylformamide;

(2) the copper acetylacetonate of 6mmol and the sodium oleate of 1mmol are added in the mixed solution of step 1, with the rotating speed of 4000r/min magnetic stirring 1 hour, obtain reaction solution;

(3) the reaction solution in the step 2 is transferred to the polytetrafluoroethylene reactor of 80 mL, after sealing, the temperature is programmed to 150 ° C, the heating rate is 8 ° C/min, and the reaction is performed for 8 hours to obtain the product;

(4) washing with water and ethanol three times, drying in an oven at 60° C. for 24 hours, and placing the dried product in a mortar for grinding and dispersion to obtain a copper/cuprous oxide heterojunction nanosheet catalyst.

The topography (transmission electron microscope) of the obtained powder is shown in FIG. 3 . It can be seen that the obtained copper/cuprous oxide heterojunction catalyst has a nanosheet morphology.

Example 4

A preparation method of a copper/cuprous oxide heterojunction nanosheet catalyst adopts the following steps:

(1) 10mL of N,N-dimethylformamide was added to 35mL of ethanol, magnetic stirring, wherein the rotating speed was 2000r/min, to obtain a mixed solution of ethanol and N,N-dimethylformamide;

(2) the copper acetylacetonate of 7mmol and the sodium oleate of 1mmol are added in the mixed solution of step 1, with the rotating speed of 2000r/min magnetic stirring 1 hour, obtain reaction solution;

(3) the reaction solution in the step 2 was transferred to the 90mL polytetrafluoroethylene reactor, after sealing, the temperature was programmed to 180°C, and the heating rate was 9°C/min, and the reaction was performed for 8 hours to obtain the product;

(4) Washing three times with water and ethanol, drying in an oven at 60° C. for 24 hours, and placing the dried product in a mortar to grind and disperse to obtain a copper/cuprous oxide heterojunction nanosheet catalyst.

The topography (transmission electron microscope) of the obtained powder is shown in FIG. 4 . It can be seen that the obtained copper/cuprous oxide heterojunction catalyst has nanosheet morphology.

The copper/cuprous oxide heterojunction nanosheet catalyst obtained in Example 1 was subjected to X-ray diffraction (XRD) analysis, and the obtained XRD pattern was shown in FIG. 5 . By comparing the JCPDF standard card (85-1326) of copper and the JCPDF standard card (74-1230) of cuprous oxide, it is obvious that the obtained copper/cuprous oxide heterojunction nanosheet catalyst is composed of two components of copper and cuprous oxide. composition of different substances. The diffraction peak intensity is high, and the peak shape is slightly broadened, indicating that the sample is of high purity and the morphology is at the nanometer scale.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, and substitutions can be made in these embodiments without departing from the principle and spirit of the invention and modifications, the scope of the present invention is defined by the appended claims and their equivalents.

Claims (10)

1. a preparation method of copper/cuprous oxide heterojunction nanosheet catalyst, is characterized in that, comprises the steps: Step 1. Add the organic solvent to the alcohol solvent and stir to obtain a mixed solution; Step 2. adding copper acetylacetonate and surfactant into the mixed solution, stirring vigorously to obtain a reaction solution; Step 3. Transfer the reaction solution to a polytetrafluoroethylene reaction kettle, and after sealing, heat up to 100-200° C. to obtain a product; Step 4. Washing, drying and grinding the product to obtain the copper/cuprous oxide heterojunction nanosheet catalyst. 2. preparation method according to claim 1 is characterized in that, in step 1, described organic solvent is selected from N,N-dimethylformamide, N-methylpyrrolidone and derivatives thereof or any of them combination; or Preferably, in step 1, the alcohol solvent is selected from C _1-6 alcohols, preferably methanol, ethanol and derivatives thereof or any combination thereof; or Preferably, in step 1, the volume ratio of the alcohol solvent to the organic solvent is 1:1-6:1. 3. preparation method according to claim 1 is characterized in that, in step 2, described surfactant is cetyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide, poly Vinylpyrrolidone, sodium oleate, or any combination thereof. 4. preparation method according to claim 1 is characterized in that, in step 2, the mol ratio of copper acetylacetonate and described surfactant is 6:1-8:1. 5. preparation method according to claim 1, is characterized in that, in step 1 or 2, uses magnetic stirrer to stir, rotating speed is 1000-4000r/min, and time is 10 minutes to 1 hour. 6. The preparation method according to claim 1, characterized in that, in step 3, the volume ratio of the volume of the reaction solution to the polytetrafluoroethylene reactor is 1:2-1:4. 7. preparation method according to claim 1, is characterized in that, in step 3, described temperature rise is programmed temperature rise to reaction temperature; Preferably, temperature rise rate is 5-10 ℃/min; Preferably, reaction time is 6-12 hours. 8. The preparation method according to claim 1, characterized in that, in step 4, the washing is to use deionized water to wash until the pH value of the supernatant is 7, and then use absolute ethanol to wash twice. 9 . The preparation method according to claim 1 , wherein, in step 4, the drying is treatment at 60-80° C. for 8-24 hours. 10 . 10. A copper/cuprous oxide heterojunction nanosheet catalyst prepared by the method according to any one of claims 1-9.

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