Copper-indium bimetal organic framework catalyst as well as preparation method and application thereof

Abstract

The invention provides a copper-indium bimetal organic framework catalyst and a preparation method and application thereof, the copper-indium bimetal organic framework catalyst comprises a foamy copper substrate and a copper-indium bimetal organic framework, the copper-indium bimetal organic framework is a nano column or nano particle, and the copper-indium bimetal organic framework is distributed on the surface of the foamy copper substrate. According to the catalyst, the copper-indium bimetal organic framework grows on the foamy copper substrate, the nanoscale copper-indium bimetal organic framework is used for effectively promoting the reaction to be carried out in the methane generation direction, the problem that an existing copper-based catalyst is poor in product selectivity is solved, and the methane generation rate is effectively increased.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide electro-reduction catalysis, and in particular to a copper-indium bimetallic organic framework catalyst and a preparation method and application thereof. Background Art

[0002] As the impact of the greenhouse effect on the ecological environment becomes increasingly apparent, people are gradually paying more attention to the greenhouse effect, among which carbon dioxide is the main cause of the greenhouse effect. Electrocatalytic reduction of carbon dioxide is currently generally considered to be an effective means of converting excess carbon dioxide in the atmosphere into industrial raw materials and fuels. The products of the carbon dioxide electroreduction reaction include one-carbon compounds such as carbon monoxide, formic acid, methanol, and methane, two-carbon compounds such as ethylene, ethanol, ethylene glycol, acetic acid, and oxalic acid, and even three-carbon compounds such as propylene, n-propanol, propionaldehyde, and acetone. Although there are many types of products from the electroreduction of carbon dioxide, the electroreduction of carbon dioxide still has problems such as slow reaction speed, low conversion rate, and poor selectivity that need to be solved.

[0003] Currently, the electroreduction of carbon dioxide to methane has been widely studied, but the reaction path is still very challenging because it involves the transfer of 8 electrons and 8 protons. On the other hand, copper is considered to be an effective element for converting carbon dioxide into methane, but copper-based catalysts currently still face problems such as high overpotential and poor product selectivity, which are still unsatisfactory. Summary of the invention

[0004] The present invention provides a copper-indium bimetallic organic framework catalyst. The catalyst utilizes a foam copper substrate to grow a copper-indium bimetallic organic framework, and utilizes the nanoscale copper-indium bimetallic organic framework to effectively promote the reaction in the direction of generating methane, thereby solving the problem of poor product selectivity of existing copper-based catalysts and effectively improving the generation rate of methane.

[0005] To solve the above technical problems, the present invention provides a copper-indium bimetallic organic framework catalyst, comprising: a foam copper substrate and a copper-indium bimetallic organic framework, wherein the copper-indium bimetallic organic framework is a nanocolumn or nanoparticle, and the copper-indium bimetallic organic framework is distributed on the surface of the foam copper substrate.

[0006] In this case, the copper-indium bimetallic organic framework catalyst is divided into two parts: a foam copper substrate and a copper-indium bimetallic organic framework. The setting of the foam copper substrate enables the copper-indium bimetallic organic framework to grow densely, and the copper-indium bimetallic organic framework is in a nano form and carries more copper and indium ions on the surface, thereby effectively increasing the production rate of carbon dioxide electroreduction to methane and promoting the reaction.

[0007] In a preferred or optional embodiment, the copper indium bimetallic organic framework is a nanorod, and the copper indium bimetallic organic framework has a length of 50 nm-200 nm and a diameter of 10 nm-50 nm.

[0008] In a preferred or alternative embodiment, nitrogen-containing organic ligands are used in the copper-indium bimetallic organic framework.

[0009] The present invention also provides a method for preparing a copper-indium bimetallic organic framework catalyst, comprising:

[0010] S100: mixing indium trichloride, cupric chloride dihydrate, and deionized water in a mass ratio of (0.01-8.85):(0.01-9.55):(4000-4200) to obtain a first mixed material;

[0011] S200: mixing 2-methylimidazole and deionized water in a mass ratio of (20-24): (4000-4200) to obtain a second mixture;

[0012] S300: mixing the first mixed material and the second mixed material in a mass ratio of (10-12):(9-11), and ultrasonically stirring to obtain a third mixed material;

[0013] S400: putting the third mixed material into a reactor, adding copper foam, and then performing a hydrothermal reaction. After the reaction, taking out the copper foam, washing and drying it, and obtaining a copper-indium bimetallic organic framework catalyst.

[0014] In this case, the copper-indium bimetallic organic framework catalyst can be simply and quickly prepared by the above method. The steps are simple and efficient, which is convenient for the industrial production of the copper-indium bimetallic organic framework catalyst.

[0015] In a preferred or optional embodiment, in S300, after the first mixture and the second mixture are mixed, they are first stirred with a magnetic stirrer at a speed of 600 r / min-800 r / min for 15 min-25 min, and then ultrasonically stirred for 15 min-25 min.

[0016] In a preferred or optional embodiment, in S400, the inner lining of the reactor is made of polytetrafluoroethylene material.

[0017] In a preferred or optional embodiment, in S400, the length of the copper foam is 1.5 cm-5 cm, the width is 1.5 cm-5 cm, and the thickness of the copper foam is 0.2 mm-20 mm.

[0018] In a preferred or optional embodiment, in S400, the reaction temperature of the hydrothermal reaction is controlled to be 55° C.-70° C., and the reaction time is controlled to be 20 h-30 h.

[0019] The present invention also provides an application of the copper-indium bimetallic organic framework catalyst, wherein the copper-indium bimetallic organic framework catalyst is used to catalyze the electroreduction of carbon dioxide to generate methane.

[0020] In this case, the copper-indium bimetallic organic framework catalyst is applied to the reaction of carbon dioxide electroreduction to generate methane, which can effectively catalyze the reaction in the direction of methane generation and increase the methane generation rate.

[0021] In a preferred or optional embodiment, the total current density of the copper indium bimetallic organic framework catalyst exceeds 200 mA / cm at a voltage of -1.54 V (vs. RHE). 2 .

[0022] In summary, the present invention has the following beneficial effects:

[0023] (1) The copper-indium bimetallic organic framework catalyst of the present invention can effectively promote the electroreduction reaction of carbon dioxide to generate methane, and significantly inhibit the generation of hydrogen. At the same time, the copper-indium bimetallic organic framework catalyst of the present invention has good catalytic activity, and its total current density is greater than that of conventional single copper and single indium catalysts. The Faraday efficiency of methane and the Faraday efficiency of total carbon products are both high;

[0024] (2) The copper-indium bimetallic organic framework catalyst of the present invention can enhance the catalytic effect because under the reduction potential, the two copper sites cannot undergo coupling reaction due to their long distance, and the formed carbon-hydrogen intermediate will combine with the hydrogen ions provided by the indium site that is closer, thereby generating methane products. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a microscopic morphology of the copper-indium bimetallic organic framework catalyst prepared in Example 1 provided by the present invention;

[0026] Figure 2 This is an EDX image of the copper-indium bimetallic organic framework catalyst prepared in Example 1 provided by the present invention;

[0027] Figure 3 This is a microscopic morphology of the copper metal organic framework catalyst prepared in Comparative Example 1 provided by the present invention;

[0028] Figure 4 This is a microscopic morphology of the copper metal organic framework catalyst prepared in Comparative Example 2 provided by the present invention;

[0029] Figure 5 This is a graph showing the CO2RR performance test results of the copper-indium bimetallic organic framework catalyst prepared in Example 1 provided by the present invention;

[0030] Figure 6 This is a graph showing the CO2RR performance test results of the copper metal organic framework catalyst prepared in Comparative Example 1 provided by the present invention;

[0031] Figure 7 This is a graph showing the CO2RR performance test results of the copper metal organic framework catalyst prepared in Comparative Example 2 provided by the present invention;

[0032] Figure 8 The results of total current density tests on the catalysts prepared in Example 1, Comparative Example 1 and Comparative Example 2 provided by the present invention are shown in FIG.

[0033] Fig. 9 The results of the methane Faraday efficiency test of the catalysts prepared in Example 1, Comparative Example 1 and Comparative Example 2 provided by the present invention are shown in FIG. DETAILED DESCRIPTION

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below.

[0035] Example 1

[0036] This embodiment provides a method for preparing a copper-indium bimetallic organic framework catalyst, comprising:

[0037] S100: Weigh 0.0531 g of indium trichloride and 0.0955 g of cupric chloride dihydrate and add them to 40 mL of deionized water to obtain a first mixture;

[0038] S200: weigh 0.2176 g of 2-methylimidazole and add it to 40 mL of deionized water to obtain a second mixture;

[0039] S300: all the first mixed materials and all the second mixed materials are mixed, first stirred at a speed of 700 r / min for 20 min using a magnetic stirrer, and then ultrasonically stirred for 20 min to obtain a third mixed material;

[0040] S400: The third mixture is put into a polytetrafluoroethylene liner, and 2 cm×2 cm copper foam is added, and then a hydrothermal reaction is carried out. The reaction temperature of the hydrothermal reaction is controlled to be 60°C and the reaction time is 24 hours. After the reaction, the copper foam is taken out, rinsed with deionized water several times, and then placed in a vacuum drying oven for 24 hours to obtain a copper-indium bimetallic organic framework catalyst.

[0041] Example 2

[0042] This embodiment provides a method for preparing a copper-indium bimetallic organic framework catalyst, comprising:

[0043] S100: Weigh 0.0884 g of indium trichloride and 0.0341 g of cupric chloride dihydrate and add them to 40 mL of deionized water to obtain a first mixture;

[0044] S200: weigh 0.2176 g of 2-methylimidazole and add it to 40 mL of deionized water to obtain a second mixture;

[0045] S300: all the first mixed materials and all the second mixed materials are mixed, first stirred at a speed of 650 r / min for 17 minutes using a magnetic stirrer, and then ultrasonically stirred for 23 minutes to obtain a third mixed material;

[0046] S400: The third mixture is put into a polytetrafluoroethylene liner, and 3 cm×2 cm copper foam is added, and then a hydrothermal reaction is carried out. The reaction temperature of the hydrothermal reaction is controlled to be 55°C and the reaction time is 30 hours. After the reaction, the copper foam is taken out, rinsed with deionized water several times, and placed in a vacuum drying oven for 24 hours to obtain a copper-indium bimetallic organic framework catalyst.

[0047] Example 3

[0048] This embodiment provides a method for preparing a copper-indium bimetallic organic framework catalyst, comprising:

[0049] S100: Weigh 0.0221 g of indium trichloride and 0.0682 g of cupric chloride dihydrate and add them into 40 mL of deionized water to obtain a first mixture;

[0050] S200: weigh 0.2176 g of 2-methylimidazole and add it to 40 mL of deionized water to obtain a second mixture;

[0051] S300: all the first mixed materials and all the second mixed materials are mixed, first stirred at a speed of 750 r / min for 24 minutes using a magnetic stirrer, and then ultrasonically stirred for 16 minutes to obtain a third mixed material;

[0052] S400: The third mixture is put into a polytetrafluoroethylene liner, and 2cm×4cm of foamed copper is added, and then a hydrothermal reaction is carried out. The reaction temperature of the hydrothermal reaction is controlled to be 65°C and the reaction time is 20h. After the reaction, the foamed copper is taken out, rinsed with deionized water several times, and then placed in a vacuum drying oven for 24h to obtain a copper-indium bimetallic organic framework catalyst.

[0053] Comparative Example 1

[0054] This embodiment provides a method for preparing a copper metal organic framework catalyst, comprising:

[0055] S100: Weigh 0.0682 g of cupric chloride dihydrate and add it to 40 mL of deionized water to obtain a first mixture;

[0056] S200: weigh 0.2176 g of 2-methylimidazole and add it to 40 mL of deionized water to obtain a second mixture;

[0057] S300: all the first mixed materials and all the second mixed materials are mixed, first stirred at a speed of 700 r / min for 20 min using a magnetic stirrer, and then ultrasonically stirred for 20 min to obtain a third mixed material;

[0058] S400: The third mixture is put into a polytetrafluoroethylene liner, and 2 cm×2 cm copper foam is added, and then a hydrothermal reaction is carried out. The reaction temperature of the hydrothermal reaction is controlled to be 60°C and the reaction time is 24 hours. After the reaction, the copper foam is taken out, rinsed with deionized water several times, and then placed in a vacuum drying oven for 24 hours to obtain a copper metal organic framework catalyst.

[0059] Comparative Example 2

[0060] This embodiment provides a method for preparing an indium metal organic framework catalyst, comprising:

[0061] S100: Weigh 0.0885 g of indium trichloride and add it to 40 mL of deionized water to obtain a first mixed material;

[0062] S200: weigh 0.2176 g of 2-methylimidazole and add it to 40 mL of deionized water to obtain a second mixture;

[0063] S300: all the first mixed materials and all the second mixed materials are mixed, first stirred at a speed of 700 r / min for 20 min using a magnetic stirrer, and then ultrasonically stirred for 20 min to obtain a third mixed material;

[0064] S400: The third mixture is put into a polytetrafluoroethylene liner, and 2 cm×2 cm copper foam is added, and then a hydrothermal reaction is carried out. The reaction temperature of the hydrothermal reaction is controlled to be 60°C and the reaction time is 24 hours. After the reaction, the copper foam is taken out, rinsed with deionized water several times, and then placed in a vacuum drying oven for 24 hours to obtain an indium metal organic framework catalyst.

[0065] Performance Testing

[0066] The copper-indium bimetallic organic framework catalyst prepared in Example 1 was tested by scanning electron microscopy. The test results are as follows: Figure 1 , Figure 2 As shown. Figure 1 This is a morphology diagram of the copper-indium bimetallic organic framework catalyst. From the diagram, it can be seen that the surface of the copper-indium bimetallic organic framework catalyst is in the shape of nano-columns and is evenly distributed on the surface of the copper foam. Figure 2This is the EDX image corresponding to the mirror. The upper right corresponds to the copper element, the lower right corresponds to the indium element, and the lower left corresponds to the oxygen element. It can be seen that the three elements of copper, indium and oxygen are evenly distributed on the foam copper.

[0067] The copper metal organic framework catalyst prepared in Comparative Example 1 was tested by scanning electron microscopy. The test results are as follows: Figure 3 As shown in the figure, it can be seen that there are granular samples distributed on the surface of the copper foam on the copper metal organic framework catalyst, and the surface of the copper foam is obviously corroded. The corrosion of the catalyst will lead to fewer catalytic sites, which is not conducive to the electroreduction reaction of carbon dioxide, and will also lead to a decrease in subsequent products after long-term electrolysis.

[0068] The indium metal organic framework catalyst prepared in Comparative Example 2 was tested by scanning electron microscopy. The test results are as follows: Figure 4 As shown, it can be seen that there are a small amount of granular samples distributed on the surface of the copper foam on the indium metal organic framework catalyst. Because the indium sites provide more hydrogen ions, the close distance between the indium sites will cause the hydrogen ions to combine with each other to generate hydrogen, thereby inhibiting the carbon dioxide electroreduction reaction.

[0069] The catalysts prepared in Example 1, Comparative Example 1 and Comparative Example 2 were tested for CO2RR performance. The test results are as follows: Figure 5-Figure 7 As shown. The gases and their contents produced in the CO2RR performance test are detected by gas chromatography (Tsushima GC2014C). The specific detection method is as follows: Before electrolysis, the carbon dioxide gas is introduced into the cathode chamber of the H-type electrolytic cell through a hose, and then the H-type electrolytic cell and the gas chromatograph are connected with a hose. Before the experiment, carbon dioxide is introduced into the cathode liquid to saturate its carbon dioxide content. The electrolysis time is set to 40 minutes. At 15 minutes and 30 minutes of electrolysis, the gas in the cathode chamber of the H-type electrolytic cell is introduced into the gas chromatograph for detection. Figure 5 It can be seen that the product generated by the copper-indium bimetallic organic framework catalyst is mainly methane. Under the condition of -1.54V (vs.RHE), its maximum Faraday efficiency of methane reaches 77%. At the same time, due to the significant inhibition of the hydrogen evolution reaction, the Faraday efficiency of hydrogen is kept below 25% in the range of -1.54V (vs.RHE) to -1.14V (vs.RHE). Figure 6 , Figure 7 By comparing the data in , it can be seen that the copper metal organic framework catalyst mainly promotes the production of ethylene, and the indium metal organic framework catalyst mainly promotes the production of hydrogen. Both of them have a poor promoting effect on the production of methane, far less than the copper indium bimetallic organic framework catalyst.

[0070] The total current density test was performed on the catalysts prepared in Example 1, Comparative Example 1 and Comparative Example 2. The test results are as follows: Figure 8As shown in the figure, it can be seen that the copper-indium bimetallic organic framework catalyst has good conductivity and high selectivity for carbon-containing products. At -1.54V (vs.RHE), the total current density of the copper-indium bimetallic organic framework catalyst can reach up to -214.66mA / cm 2 The total current density of the copper metal organic framework catalyst and the indium metal organic framework catalyst at the same voltage does not exceed -150mA / cm 2 .

[0071] The catalysts prepared in Example 1, Comparative Example 1 and Comparative Example 2 were tested for methane Faraday efficiency. The test results are as follows: Fig. 9 As shown in the figure, it can be seen that the effect of the copper-indium bimetallic organic framework catalyst on the applied potential is volcano-shaped, among which the highest methane Faraday efficiency is about 83%, indicating that the copper-indium bimetallic organic framework catalyst has good catalytic activity for the electroreduction of carbon dioxide to produce methane.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A copper-indium bimetallic organic framework catalyst, characterized in that: include: A foam copper substrate and a copper-indium bimetallic organic framework, wherein the copper-indium bimetallic organic framework is a nanocolumn or a nanoparticle, and the copper-indium bimetallic organic framework is distributed on the surface of the foam copper substrate.

2. The copper-indium bimetallic organic framework catalyst according to claim 1, characterized in that The copper-indium bimetallic organic framework is a nanocolumn, and the length of the copper-indium bimetallic organic framework is 50nm-200nm and the diameter is 10nm-50nm.

3. The copper-indium bimetallic organic framework catalyst according to claim 1, characterized in that The copper-indium bimetallic organic framework adopts nitrogen-containing organic ligands.

4. A method for preparing a copper-indium bimetallic organic framework catalyst, characterized in that: include: S100: mixing indium trichloride, cupric chloride dihydrate, and deionized water in a mass ratio of (0.01-8.85):(0.01-9.55):(4000-4200) to obtain a first mixed material; S200: mixing 2-methylimidazole and deionized water in a mass ratio of (20-24): (4000-4200) to obtain a second mixture; S300: mixing the first mixed material and the second mixed material in a mass ratio of (10-12):(9-11), and ultrasonically stirring to obtain a third mixed material; S400: putting the third mixed material into a reaction kettle, adding copper foam, and then performing a hydrothermal reaction. After the reaction, taking out the copper foam, washing and drying it, to obtain the copper-indium bimetallic organic framework catalyst.

5. The preparation method according to claim 4, characterized in that: In the S300, after the first mixture and the second mixture are mixed, they are first stirred with a magnetic stirrer at a speed of 600 r / min-800 r / min for 15 min-25 min, and then ultrasonically stirred for 15 min-25 min.

6. The preparation method according to claim 4, characterized in that: In the S400, the inner lining of the reactor is made of polytetrafluoroethylene material.

7. The preparation method according to claim 4, characterized in that: In the S400, the length of the copper foam is 1.5 cm-5 cm, the width is 1.5 cm-5 cm, and the thickness of the copper foam is 0.2 mm-20 mm.

8. The preparation method according to claim 4, characterized in that: In the S400, the reaction temperature of the hydrothermal reaction is controlled to be 55° C.-70° C., and the reaction time is controlled to be 20 h-30 h.

9. A use of the copper-indium bimetallic organic framework catalyst according to any one of claims 1 to 4, characterized in that: The copper-indium bimetallic organic framework catalyst is used to catalyze the electroreduction of carbon dioxide to generate methane.

10. The use of the copper-indium bimetallic organic framework catalyst according to claim 9, characterized in that: Under the voltage condition of -1.54 V (vs. RHE), the total current density of the copper-indium bimetallic organic framework catalyst exceeds 200 mA / cm 2 .

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