Basic cupric carbonate gallium-loaded composite oxide and preparation method and application thereof

Abstract

The invention discloses a basic cupric carbonate gallium-loaded composite oxide as well as a preparation method and application thereof, and a mixed solution containing copper nitrate, gallium nitrate and urea is subjected to hydrothermal reaction to obtain the basic cupric carbonate gallium-loaded composite oxide. The method provided by the invention has the advantages of simple preparation process, good repeatability and convenience in batch synthesis of the composite oxide catalyst, and the catalyst has an ultra-wide stable potential range which is as wide as-0.6 to-1.8 V in the process of preparing synthesis gas through electroreduction, and can stably adjust the CO / H2 ratio. The basic cupric carbonate gallium-loaded composite oxide is prepared, the synthesis gas is prepared through CO2 electroreduction, the efficiency of the synthesis gas is 90% or above, and the catalyst is expected to be widely applied to the field of electrocatalysis.

Description

Technical Field

[0001] The present invention relates to the field of catalyst preparation, and in particular to a basic copper carbonate-supported gallium composite oxide and a preparation method thereof and a method for preparing the same in CO 2 Synthesis gas is produced by electroreduction. Background Art

[0002] Synthesis gas (CO, H 2 ) is widely used in the preparation of chemicals, fertilizers, fuels and solvents, and is an important chemical raw material gas and intermediate. CO / H 2 (molar ratio) is generally between 0.33 and 2, with different molar ratios of CO / H 2 Synthesis gas can be used in a specific chemical reaction process to synthesize downstream products. 2 The molar ratio of CO / H is 0.3~0.5, which can be used to synthesize methane and methanol. 2 The molar ratio of CO is 0.5~1, which can be used for Fischer-Tropsch product synthesis. At present, synthesis gas is mainly produced by gasification of solid fuels such as coal or coke and light hydrocarbons such as natural gas and naphtha. 2 The electroreduction reaction is driven by renewable energy and operates under normal temperature and pressure conditions. It is a sustainable energy conversion method with great potential.

[0003] CO 2 Electroreduction to produce syngas requires simultaneous control of CO 2 The electroreduction rate and hydrogen evolution reaction rate require optimization of the catalyst structure to have suitable catalyst active sites for the syngas production. 1 and C 2 The intermediate has moderate adsorption energy and is widely used in CO 2 Electroreduction reaction to produce syngas system. However, most of the current Cu-based catalysts for producing syngas have a narrow potential range ( Fuel 2025,392,134821; J. Power Sources 2022, 535,231453), but in the application scenario, the potential range of renewable energy often fluctuates greatly, which directly affects the product selectivity of the catalyst. Therefore, the preparation of a Cu-based catalyst system that can stably generate syngas in an ultra-wide potential range can promote CO 2 Industrial process of preparing synthesis gas by electroreduction reaction. Summary of the invention

[0004] Purpose of the invention: The technical problem to be solved by the present invention is to provide a method for preparing gallium-supported composite oxide of basic copper carbonate and its preparation in CO 2 Application of electroreduction in the preparation of synthesis gas.

[0005] In order to solve the above technical problems, the present invention discloses the following technical solutions: In a first aspect, the present invention discloses a basic copper carbonate-supported gallium composite oxide and a preparation method thereof.

[0006] In the preparation method, water is used as a solvent, gallium nitrate and copper nitrate are used as a gallium source and a copper source respectively, and urea is used as an alkali source.

[0007] Specifically, the preparation method of the basic copper carbonate-supported gallium composite oxide comprises dissolving gallium nitrate, copper nitrate and urea in water, ultrasonicating, stirring, mixing evenly, and hydrothermally reacting to obtain a reaction solution containing the basic copper carbonate-supported gallium composite oxide; the obtained reaction solution is cooled to room temperature, fully washed with deionized water, centrifuged, and dried at 60-80° C. for 18-24 hours to obtain the basic copper carbonate-supported gallium composite oxide.

[0008] Wherein, the molar ratio of gallium nitrate to copper nitrate is 1:20~1:1.

[0009] Wherein, the molar ratio of the copper nitrate to urea is 1:2-8, such as 1:4-6.

[0010] Wherein, the concentration of copper nitrate in the mixed solution is 0.085-0.145 mmol / mL, such as 0.095-0.125 mmol / mL.

[0011] Wherein, the ultrasonication is to completely dissolve the mixture, such as ultrasonication for 30 to 60 minutes.

[0012] The stirring is performed until the mixture is uniformly mixed, such as stirring for 0.5 to 1 hour.

[0013] Wherein, the temperature of the hydrothermal reaction is 110~120℃.

[0014] Wherein, the hydrothermal reaction time is 18~24h.

[0015] In a second aspect, the present invention discloses the above-mentioned gallium-supported composite oxide of basic copper carbonate as a catalyst for CO 2 Application of electroreduction in the preparation of synthesis gas.

[0016] The application is to prepare an electrode by using the basic copper carbonate-supported gallium composite oxide, and the electrode is used for electrocatalysis of CO 2 Synthesis gas is produced by electroreduction.

[0017] The ink containing the basic copper carbonate-supported gallium composite oxide, electrolyte and solvent is dispersed on an electrode substrate and dried to obtain an electrode.

[0018] Wherein, the electrolyte includes Nafion solution, such as 5% Nafion solution; the solvent includes isopropanol; the electrode substrate includes carbon paper; the dosage ratio of the basic copper carbonate-supported gallium composite oxide, the electrolyte, and the solvent is 8~12 mg: 15~25 uL: 800~1200 uL, such as 10 mg: 18~22 uL: 900~1100 uL.

[0019] The catalyst loading in the electrode is 0.5-1.5 mg / cm 2 Electrode substrate, such as 1 mg / cm 2 Electrode substrate.

[0020] The electrode is used as the working electrode, the platinum sheet is used as the counter electrode, and the saturated silver chloride electrode is used as the reference electrode. In this H-type electrolytic cell three-electrode system, the electrocatalytic CO 2 Further, the current density can reach up to 50 mA / cm by using the constant potential method. 2 .

[0021] Wherein, the electrocatalysis is carried out with 0.05-0.2 M KHCO 3 As electrolyte, CO 2 The flow rate was 18-22 sccm and the electrolysis time was 55-65 min.

[0022] Among them, the stable potential for preparing synthesis gas by electroreduction is relatively wide, ranging from -0.6 to -1.8 V.

[0023] Beneficial Effects

[0024] 1. The method provided by the present invention has the advantages of simple preparation process, good repeatability, and convenient batch synthesis of composite oxide catalysts. In addition, the catalyst has an ultra-wide stable potential range in the process of preparing synthesis gas through electroreduction, which is as wide as -0.6~-1.8V, and can stably adjust CO / H 2 Compare.

[0025] 2. The present invention prepares basic copper carbonate gallium composite oxide, CO 2 Synthesis gas is prepared by electro-reduction with a synthesis gas efficiency of over 90%. This catalyst is expected to be widely used in the field of electrocatalysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0027] Figure 1 This is the X-ray diffraction pattern of the basic copper carbonate-supported gallium composite oxide prepared in Example 1 of the present invention.

[0028] Figure 2 This is a transmission electron microscope image of the basic copper carbonate-supported gallium composite oxide prepared in Example 1 of the present invention.

[0029] Figure 3 It is a diagram showing the synthesis gas efficiency and ratio of the basic copper carbonate-supported gallium composite oxide prepared in Example 1 of the present invention.

[0030] Figure 4 This is the X-ray diffraction pattern of the basic copper carbonate-supported gallium composite oxide prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0031] The present invention can be better understood according to the following examples. However, it is easy for those skilled in the art to understand that the contents described in the examples are only used to illustrate the present invention, and should not and will not limit the present invention described in detail in the claims.

[0032] The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0033] The following embodiment provides a method for preparing a gallium-supported composite oxide of basic copper carbonate, which can be rapidly synthesized in large quantities with good dispersibility and high repeatability within a wide range of gallium to copper molar ratios by a simple hydrothermal process, and can be electro-reduced to generate a stable ratio of synthesis gas under an ultra-wide potential.

[0034] Example 1

[0035] Add 5 mmol of gallium nitrate, 5 mmol of copper nitrate and 25 mmol of urea to 40 mL of water, sonicate until completely dissolved, and stir thoroughly for 1 hour until the mixed solution is completely uniform. The obtained mixed solution is transferred to a 50 mL stainless steel reactor lined with polytetrafluoroethylene, placed in a forced air drying oven, and hydrothermally reacted at 110°C for 24 hours. Then cool naturally to room temperature, wash the obtained precipitate thoroughly with deionized water, centrifuge, and dry in an oven at 60°C for 24 hours to obtain basic copper carbonate-supported gallium composite oxide. The X-ray diffraction spectrum of basic copper carbonate-supported gallium composite oxide is shown in Figure 1 The positions and intensities of the diffraction peaks are consistent with those of the standard cards of basic copper carbonate (JCPDS 41-1390) and gallium hydroxide (JCPDS 54-0910). Figure 2 , where the lattice fringes d=0.302 correspond to the (230) crystal plane of basic copper carbonate, and the lattice fringes d=0.254 correspond to the (021) crystal plane of gallium hydroxide.

[0036] CO 2Electroreduction reaction evaluation: 10 mg of basic copper carbonate-supported gallium composite oxide catalyst was added to 20 uL of 5% Nafion solution and 1000 uL of isopropanol to prepare ink solution. Ultrasonic dispersion was performed for 30 minutes. 25 uL of ink solution was dispersed in 0.25 cm 2 The catalyst loading on the carbon paper was about 1 mg / cm 2 , dried under an infrared lamp for 10 min, and used as the working electrode. The H-type electrolytic cell three-electrode system (with a platinum sheet as the counter electrode, a saturated silver chloride electrode as the reference electrode, and a working electrode) was used for testing using a constant potential method, with a current density of up to 50 mA / cm 2 , CO 2 Flow rate: 20 sccm, 0.1 M KHCO 3 The electrolyte was used for electrolysis for 60 min. The gas phase products were detected by gas chromatography and the liquid phase products were detected by liquid nuclear magnetic resonance. The voltage was applied by the electrochemical workstation during the entire electrochemical reaction and the current-time curve was recorded. The catalytic results are shown in Figure 3 , between -0.8~-1.8V, stable synthesis gas is generated, CO / H 2 The ratio is between 0.15 and 0.37, and between -0.6 and -1.4 V, and the synthesis gas efficiency exceeds 90%.

[0037] The method for preparing synthesis gas in the following embodiments and comparative examples is the same as that of the present application, except that the basic copper carbonate-supported gallium composite oxide catalyst in the working electrode is replaced with the catalyst of the embodiments and comparative examples.

[0038] Example 2

[0039] Add 0.5 mmol of gallium nitrate, 5 mmol of copper nitrate and 25 mmol of urea to 40 mL of water, sonicate until completely dissolved, and stir thoroughly for 1 hour until the mixed solution is completely uniform. The resulting mixed solution is transferred to a 50 mL stainless steel reactor lined with polytetrafluoroethylene, placed in a forced air drying oven, and hydrothermally reacted at 110°C for 24 hours. Then cool naturally to room temperature, wash the resulting precipitate thoroughly with deionized water, centrifuge, and dry in an oven at 60°C for 24 hours to obtain a basic copper carbonate-supported gallium catalyst. The X-ray diffraction pattern of the basic copper carbonate-supported gallium catalyst is shown in Figure 4 Due to the low gallium content, no characteristic signal of gallium was observed on the spectrum. Between -0.6 and -1.8 V, stable synthesis gas was generated, CO / H 2 The ratio is between 0.92 and 2.1.

[0040] Example 3

[0041] Add 0.25 mmol of gallium nitrate, 5 mmol of copper nitrate and 25 mmol of urea to 40 mL of water, ultrasonicate until completely dissolved, and stir thoroughly for 1 hour until the mixed solution is completely uniform. The obtained mixed solution is transferred to a 50 mL stainless steel reactor lined with polytetrafluoroethylene, placed in a forced air drying oven, and hydrothermally reacted at 110°C for 24 hours. Then cool naturally to room temperature, wash the obtained precipitate with deionized water, centrifuge, and dry in an oven at 60°C for 24 hours to obtain a gallium-supported basic copper carbonate catalyst. Between -0.6 and -1.8V, a stable synthesis gas is generated, CO / H 2 The ratio is between 0.93 and 1.78.

[0042] Example 4

[0043] Add 1 mmol of gallium nitrate, 5 mmol of copper nitrate and 25 mmol of urea to 40 mL of water, ultrasonicate until completely dissolved, and stir thoroughly for 1 hour until the mixed solution is completely uniform. The obtained mixed solution is transferred to a 50 mL stainless steel reactor lined with polytetrafluoroethylene, placed in a forced air drying oven, and hydrothermally reacted at 110°C for 24 hours. Then cool naturally to room temperature, wash the obtained precipitate with deionized water, centrifuge, and dry in an oven at 60°C for 24 hours to obtain a gallium-supported basic copper carbonate catalyst. Between -0.6 and -1.8V, a stable synthesis gas is generated, CO / H 2 The ratio is between 0.47 and 1.23.

[0044] It can be seen that the present invention provides a basic copper carbonate-supported gallium composite oxide catalyst, which can be electro-reduced to prepare a synthesis gas with a stable ratio under an ultra-wide potential. Specifically, the present invention can obtain a basic copper carbonate-supported gallium composite oxide with an adjustable synthesis gas ratio by adjusting the molar ratio of gallium and copper. The synthesis method has the advantages of simple process, low cost, relatively uniform product morphology and size, large-scale synthesis and good repeatability; the basic copper carbonate-supported gallium composite oxide synthesized by the method has a stable synthesis gas ratio under the condition of CO 2 In the electroreduction reaction, a stable ratio of synthesis gas can be generated in an ultra-wide potential of -0.6~-1.8V.

[0045] Comparative Example 1 5 mmol of copper nitrate and 25 mmol of urea were added to 40 mL of water, ultrasonicated until completely dissolved, and stirred for 1 hour until the mixed solution was completely uniform. The obtained mixed solution was transferred to a 50 mL stainless steel reactor lined with polytetrafluoroethylene, placed in a forced air drying oven, and hydrothermally reacted at 110°C for 24 hours. Then it was naturally cooled to room temperature, the obtained precipitate was fully washed with deionized water, centrifuged, and dried in an oven at 60°C for 24 hours to obtain a basic copper carbonate catalyst. Between -0.6 and -1.8V, a stable synthesis gas is generated, CO / H 2 The ratio is between 0.50 and 0.69.

[0046] Comparative Example 2 5 mmol of zinc nitrate, 5 mmol of copper nitrate and 25 mmol of urea were added to 40 mL of water, ultrasonicated until completely dissolved, and stirred for 1 hour until the mixed solution was completely uniform. The obtained mixed solution was transferred to a 50 mL stainless steel reactor lined with polytetrafluoroethylene, placed in a blast drying oven, and hydrothermally reacted at 110°C for 24 hours. Then it was naturally cooled to room temperature, the obtained precipitate was fully washed with deionized water, centrifuged, and dried in an oven at 60°C for 24 hours to obtain a copper-zinc composite catalyst. It was used to prepare synthesis gas, and the results are shown in Table 1.

[0047] Table 1

[0048] Comparative Example 3 10 mmol of aluminum nitrate, 5 mmol of copper nitrate and 30 mmol of urea were added to 40 mL of water, ultrasonicated until completely dissolved, and stirred for 1 hour until the mixed solution was completely uniform. The obtained mixed solution was transferred to a 50 mL stainless steel reactor lined with polytetrafluoroethylene, placed in a forced air drying oven, and hydrothermally reacted at 110°C for 24 hours. Then it was naturally cooled to room temperature, the obtained precipitate was fully washed with deionized water, centrifuged, and dried in an oven at 60°C for 24 hours to obtain a copper-aluminum composite catalyst. It was used to prepare synthesis gas, with a stable potential range of -0.9~-1.2V, CO / H 2 The ratio is 2.56~4.72.

[0049] It can be seen that the basic copper carbonate catalyst used to generate synthesis gas has a very wide potential, but it cannot adjust the CO / H 2 Copper-zinc composite catalyst and copper-aluminum composite catalyst can adjust the CO / H ratio. 2 However, its stable potential range is narrow. During application, the potential range often fluctuates greatly, so CO / H 2The specific fluctuation is also large, and the output cannot be stable. The resulting synthesis gas is difficult to be directly used to prepare the corresponding products.

[0050] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a basic copper carbonate-supported gallium composite oxide, characterized in that: A mixed solution containing copper nitrate, gallium nitrate and urea is subjected to hydrothermal reaction to obtain basic copper carbonate-supported gallium composite oxide.

2. The preparation method according to claim 1, characterized in that: The molar ratio of copper nitrate to gallium nitrate is 1:20 to 1:

1.

3. The preparation method according to claim 1, characterized in that: The molar ratio of the copper nitrate to the urea is 1:2-8.

4. The preparation method according to claim 1, characterized in that: The solvent of the mixed solution is water; the concentration of copper nitrate in the mixed solution is 0.085-0.145 mmol / mL.

5. The preparation method according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 110-120° C., and the time of the hydrothermal reaction is 18-24 hours.

6. A basic copper carbonate-supported gallium composite oxide, characterized in that: Made by any one of the methods of claims 1 to 5.

7. An electrode, characterized in that: It is made from the basic copper carbonate-supported gallium composite oxide as described in claim 6.

8. The electrode according to claim 7, characterized in that: The ink containing the basic copper carbonate gallium composite oxide, electrolyte and solvent is dispersed on an electrode substrate and dried to obtain an electrode.

9. Use of the electrode according to claim 7 or 8 in preparing synthesis gas by electrocatalytic CO2 electroreduction.

10. The use according to claim 9, characterized in that: The potential for CO2 electroreduction to produce synthesis gas is -0.6~-1.8V.

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