Preparation and application method of multi-morphology copper oxide nano powder

Abstract

The invention relates to a preparation and application method of multi-morphology copper oxide nano-powder, and relates to a preparation and application method of nano-powder.The method comprises the steps that copper salt and different alkaline precipitators are evenly mixed according to a certain molar ratio and then added into a high-pressure stainless steel reactor, a certain amount of reaction medium is pumped into the high-pressure stainless steel reactor; the preparation method comprises the following steps: adding a copper salt slurry precursor into a reaction medium to enable the concentration of the copper salt slurry precursor in the reaction medium to be 0.1-2.0 M, magnetically stirring, heating to 150-500 DEG C and the reaction pressure to be 0.1-20.0 MPa, keeping for 0.05-3.0 hours in the state, then cooling a reactor, collecting a reaction system, centrifuging, washing and drying in vacuum to obtain the nano-powder CuO. The preparation method is simple in process, short in reaction time, cheap and easily available in raw materials and suitable for large-scale production. The copper oxide is applied to catalysis of glycerin reaction, can effectively catalyze glycerin to be converted into lactic acid, has industrial application value, and expands the application of CuO in the aspect of alcohol catalysis.

Description

Technical Field

[0001] The present invention belongs to a method for preparing copper oxide powder and its application, and more specifically, it relates to a method for preparing and applying copper oxide nano-powders with various morphologies. Background Art

[0002] Copper oxide, as an important inorganic material, is the main component of rayon, ceramics, batteries, petroleum desulfurizer, and pesticides. Copper oxide nano-crystals exhibit excellent properties and potential application prospects in the fields of catalysis, superconductivity, ceramics, etc. Scholars at home and abroad have used methods such as thermal oxidation method (CN201510944330.0; CN201510009223.9; ChemistrySelect, 2019, 33, (4), 9529 - 9539), sol-gel method (202411795521.0), microwave method (CN201510026316.2), deposition method (ChemElectroChem, 2021, 3(8), 592 - 602; Journal of Environmental, 2024, 6, (12), 114385; CN201510763226.1; CN202010961509.8), etc. to prepare copper oxides with various morphologies such as nanowires, rods, flowers, and flakes. Although these methods have achieved the chemical preparation of different morphologies of copper oxide, there are still some problems. For example, the preparation time required by the currently used solvothermal oxidation method is too long (about 8 - 48 h), and usually some additional reagents such as stabilizers and surfactants need to be added, resulting in a reaction system and post-treatment being required. Moreover, these added reagents are usually toxic and expensive; in addition to the relatively long reaction time (24 - 48 h) required by the sol-gel method, the aging time of the precursor needs to be strictly controlled during the synthesis process, and the aging time needs to be at least more than 6 hours. At the same time, acid-base reagents need to be continuously added during all reaction operations to control the acidity and alkalinity of the precursor, which makes the operation of the reaction system more complicated and is not conducive to industrial mass production. The microwave method and the deposition method also require the use of reducing agents, surfactants, and acid-base reagents when synthesizing the precursor; the reducing agent usually needs to be heat-treated during use, and the surfactant is usually an organic substance with a high industrial cost. In addition, there are some other restrictive factors, such as complex operation, difficult availability of reaction raw materials, high cost, etc., making it difficult to realize industrial scale-up production for these methods.

[0003] The hydrothermal method is a high-temperature and rapid pyrolysis method that can quickly synthesize copper oxides through subcritical technology. Li et al. were able to rapidly synthesize Cu2S, ultrafine Cu powder, and ultrafine Cu2O within 0.5 - 3.0 h through subcritical water technology (CN201610328591.4; CN202010064710.6; CN201510009223.9; CN201310220673.3), but no reports on regulating the specific morphology of copper oxides were made.

[0004] In summary, there is an urgent need to develop a simple, easy-to-implement method for preparing nano-copper oxide powder with a short preparation time, low cost, and no subsequent treatment. The present invention develops a simple and easy hydrothermal method for rapidly preparing copper oxide nano-powders with various morphologies; the raw materials used are inexpensive; the prepared products do not require post-treatment, are easy to separate, and are suitable for large-scale production. And this copper oxide, used as a catalyst for the conversion of glycerol to lactic acid, has industrial application value and expands the application of CuO in alcohol catalysis. Summary of the Invention

[0005] The object of the present invention is to provide a method for preparing and applying copper oxide nano-powders with various morphologies. This method is used to prepare nano-copper oxide, with a short reaction time, strong applicability to raw materials; the raw materials used are inexpensive; the prepared products do not require post-treatment, are easy to separate, and are suitable for large-scale production. It is a simple and easy hydrothermal method for rapidly preparing copper oxide nano-powders with various morphologies.

[0006] The technical solution of the present invention is as follows: A method for preparing copper oxide nano-powders with various morphologies, and the specific preparation steps of the method are as follows: First, a copper salt is used as a raw material and mixed evenly with an alkali metal precipitating agent to form a slurry. Solvent is added to a high-pressure reactor. After the reactor is sealed, the temperature is then heated to 100 - 500 °C and stirred to keep the reaction pressure at 0.1 - 20.0 MPa. React for 0.05 - 3.0 h in this state, and then cool the reactor to room temperature. The mixed solution is centrifuged, washed, and vacuum dried to obtain nano-copper oxide powder; The copper salt is one or more of soluble copper salts such as copper nitrate, copper sulfate, copper acetate, and copper chloride, including but not limited to one or more mentioned in the examples; The alkaline precipitating agent is one or more of sodium carbonate, sodium bicarbonate, sodium phosphate, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, triethylamine, ammonia water, ammonium sulfate, and urea; The reaction medium is one or more of water and C1 - C4 organic alcohols; The concentration of the copper salt precursor in the reaction medium is 0.1 - 2.0 M.

[0007] The described preparation method of multi-morphology copper oxide nano-powders results in nano-copper oxide with nano-CuO crystals in the shapes of chrysanthemum-like, rod-like, hexahedral granular, polygonal coral edge-like, pyramid flake and chrysanthemum flake.

[0008] The described preparation method of multi-morphology copper oxide nano-powders yields nano-copper oxide powders with a particle size range of 5 - 50 nm.

[0009] An application method of multi-morphology copper oxide nano-powders, where the prepared multi-morphology copper oxide nano-powders are used as catalysts in the glycerol conversion reaction. The steps are as follows: Weigh copper oxide (0.5 - 2.0 g) and load it at the bottom of a batch reactor. Mix and react according to NaOH : glycerol aqueous solution (10 - 20 w%) = 0.5 - 2 : 1 (molar ratio). Control the reaction temperature at 170 - 220 °C and the reaction time at 0.5 - 8 h. After the reaction reaches equilibrium, cool it to room temperature, and collect the liquid-phase product for qualitative and quantitative analysis by liquid chromatography.

[0010] The present invention has the following advantages: The present invention uses inexpensive and easily available sodium carbonate, sodium bicarbonate, sodium phosphate, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, triethylamine, ammonia water, ammonium sulfate, and urea as basic precipitating agents, and adopts the hydrothermal method to rapidly prepare nano-copper oxide (0.05 - 3.0 h). During the entire preparation process, different morphology regulation can be completed only by adjusting the synthesis pressure (0.1 - 20.0 MPa) and temperature (100 - 500 °C) during the precursor adjustment process. The copper oxide prepared by the hydrothermal method does not require the addition of any stabilizers, surfactants, and organic ligands. This method has simple process, low cost, short reaction time, no need for post-treatment, and is suitable for large-scale production.

[0011] This method synthesizes nano-copper oxide by the hydrothermal method. The system is simple and the reaction time is extremely short. The whole process has a simple process; the preparation method has strong applicability to raw materials; the products are easily separated during the preparation process, which is conducive to industrial production. Copper oxide is used as a catalyst in the glycerol conversion reaction: According to the multi-morphology copper oxide nano-powders described in claim 1 above as a catalyst for the glycerol conversion reaction, the steps are as follows: Weigh copper oxide (0.5 - 2.0 g) and load it at the bottom of a batch reactor. Mix and react according to NaOH : glycerol aqueous solution (10 - 20 w%) = 0.5 - 2 : 1 (molar ratio). Control the reaction temperature at 170 - 220 °C and the reaction time at 0.5 - 8 h. After the reaction reaches equilibrium, cool it to room temperature, and collect the liquid-phase product for qualitative and quantitative analysis by liquid chromatography. Description of the Drawings

[0012] Figure 1 SEM spectrum of the CuO obtained in Example 1; Figure 2 This is the SEM spectrum of CuO obtained in Example 2; Figure 3 This is the SEM spectrum of CuO obtained in Example 3; Figure 4 This is the SEM spectrum of CuO obtained in Example 4; Figure 5 This is the SEM spectrum of CuO obtained in Example 5; Figure 6 This is the SEM spectrum of CuO obtained in Example 6; Figure 7 This is the SEM spectrum of CuO prepared in Example 7. DETAILED DESCRIPTION

[0013] The present invention is further described below by way of examples, but the present invention is not limited thereto.

[0014] The present invention comprises the following steps: Firstly, copper salt as a raw material and a precipitant are mixed evenly and added into a reactor, after the reactor is sealed, a reaction medium is pumped into the reactor and stirred, then the temperature is heated to 100-500°C, the reaction pressure is maintained at 0.1-15.0MPa, the reaction is carried out in this state for 0.05-3.0h, and then the reactor is cooled, the mixed solution is centrifuged, washed, and vacuum dried to obtain nano copper oxide powders with different morphologies; The copper salt is one or more of copper nitrate, copper sulfate, copper acetate and copper chloride; The precipitant is one of sodium carbonate, sodium bicarbonate, sodium phosphate, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, triethylamine, ammonia water, ammonium sulfate, and urea; The reaction medium is one or more of water and C1-C4 organic alcohol; The concentration of the copper salt precursor in the reaction medium is 0.1~2.0 M.

[0015] The reaction products are chrysanthemum-shaped, rod-shaped, hexahedral granular, polygonal block-shaped, pyramid-shaped and chrysanthemum-shaped nano-CuO crystals. Example 1

[0016] 1.5 g of copper nitrate was weighed and dissolved in an appropriate amount of distilled water to form a blue solution. Sodium hydroxide solution was added dropwise to adjust the solution pH to 10 to form a slurry. The system was stirred to mix evenly to obtain a precursor slurry. The precursor liquid was added to a high-pressure reactor, and the reaction temperature was adjusted to 150 ° C and the reaction pressure was about 2.5 MPa. After the reaction system was stable and reacted for 0.5 h, the reactor was taken out and cooled. The collected system after the reaction was fully centrifuged, washed, and dried to obtain a black nano-CuO powder with a mass of about 1.0 g.

[0017] The copper oxide prepared in Example 1 was used as a catalyst for the glycerol conversion reaction, and the catalytic steps were as follows: Weigh 0.6 g of the CuO metal oxide catalyst and load it to the bottom of a batch reactor (inner lining volume: 100 mL), where the glycerol aqueous solution is 20%, and the molar ratio of NaOH to glycerol is 1:1. React at 190 °C for 6 hours in a batch reactor. After cooling to room temperature, the supernatant and catalyst powder are obtained. After taking the supernatant, performance testing is carried out by liquid chromatography. The catalytic results are shown in Table 1. Example 2

[0018] Weigh 3.0 g of copper acetate and an appropriate amount of distilled water to form a blue solution. Dropwise add ammonia water solution to adjust the solution pH = 11 to form a slurry. Stir to make the system mix evenly to form a precursor. Add the precursor slurry to a high-pressure reactor, adjust the reaction temperature to 450 °C, and the pressure is about 15.0 MPa. After the reaction system is stable, react for 2 h, take out the reactor and perform rapid cooling treatment. Centrifuge, wash, and dry the collected reaction system sufficiently to obtain about 2.2 g of black nano-CuO powder.

[0019] The copper oxide prepared in Example 2 was used as a catalyst for the glycerol conversion reaction, and the catalytic steps were as follows: Weigh 1.5 g of the CuO metal oxide catalyst and load it to the bottom of a batch reactor (inner lining volume: 100 mL), where the glycerol aqueous solution is 20%, and the molar ratio of NaOH to glycerol is 0.5:1. React at 200 °C for 4 hours in a batch reactor. After cooling to room temperature, the supernatant and catalyst powder are obtained. After taking the supernatant, performance testing is carried out by liquid chromatography. The catalytic results are shown in Table 1. Example 3

[0020] Weigh 1.0 g of copper nitrate and an appropriate amount of distilled water to form a blue solution. Dropwise add urea solution to adjust the solution pH = 10 to form a slurry. Stir to make the system mix evenly to form a precursor. Add the precursor slurry to a high-pressure reactor, adjust the reaction temperature to 300 °C, and the pressure is about 14.5 MPa. After the reaction system is stable, react for 1 h, then let the reactor cool down naturally. Centrifuge, wash, and dry the collected reaction system sufficiently to obtain about 0.7 g of black nano-CuO powder.

[0021] The copper oxide prepared in Example 3 was used as a catalyst for the glycerol conversion reaction, and the catalytic steps were as follows: Weigh 0.6 g of the CuO metal oxide catalyst and load it to the bottom of a batch reactor (inner lining volume: 100 mL). The glycerol aqueous solution was 10%, and the molar ratio of NaOH to glycerol was 1.5:1. React at 180 °C for 5 h in the batch reactor. After cooling to room temperature, the supernatant and the catalyst powder were obtained. After taking the supernatant, performance testing was carried out by liquid chromatography. The catalytic results are shown in Table 1. Example 4

[0022] Weigh 1.5 g of copper acetate and an appropriate amount of distilled water to form a blue solution. Dropwise add sodium carbonate solution to adjust the solution pH to 9.5 to form a slurry. Stir to make the system mix evenly and call it the precursor. Add the precursor slurry to a high-pressure reactor, adjust the reaction temperature to 150 °C, and the pressure is about 1.5 MPa. After the reaction system is stable, react for 1 h, take out the reactor and perform rapid cooling treatment. Centrifuge, wash, and dry the collected reaction system to obtain about 1.0 g of black nano-CuO powder.

[0023] The copper oxide prepared in Example 4 was used as a catalyst for the glycerol conversion reaction, and the catalytic steps were as follows: Weigh 0.6 g of the CuO metal oxide catalyst and load it to the bottom of a batch reactor (inner lining volume: 100 mL). The glycerol aqueous solution was 10%, and the molar ratio of NaOH to glycerol was 1:1. React at 180 °C for 8 h in the batch reactor. After cooling to room temperature, the supernatant and the catalyst powder were obtained. After taking the supernatant, performance testing was carried out by liquid chromatography. The catalytic results are shown in Table 1. Example 5

[0024] Weigh 1.5 g of copper sulfate and an appropriate amount of distilled water to form a blue solution. Dropwise add sodium carbonate solution to adjust the solution pH to 10 to form a slurry. Stir to make the system mix evenly and call it the precursor. Add the precursor slurry to a high-pressure reactor, adjust the reaction temperature to 250 °C, and the pressure is about 4.4 MPa. After the reaction system is stable, react for 0.5 h, take out the reactor and naturally cool it to room temperature. Centrifuge, wash, and dry the collected reaction system to obtain about 1.0 g of black nano-CuO powder.

[0025] The copper oxide prepared in Example 5 was used as a catalyst for the glycerol conversion reaction, and the catalytic steps were as follows: Weigh 1.0 g of the CuO metal oxide catalyst and load it to the bottom of a batch reactor (inner lining volume: 100 mL). The glycerol aqueous solution was 20%, and the molar ratio of NaOH to glycerol was 1:1. React at 190 °C for 6 hours in the batch reactor. After cooling to room temperature, the supernatant and the catalyst powder were obtained. After taking the supernatant, performance testing was carried out by liquid chromatography. The catalytic results are shown in Table 1. Example 6

[0026] Weigh 3.0 g of copper nitrate and an appropriate amount of ethylene glycol to form a blue solution. Slowly add sodium carbonate solution drop by drop to adjust the pH of the solution to 11 to form a slurry. Stir to make the system mix evenly, which is called the precursor. Add the precursor slurry into a high-pressure reactor, adjust the reaction temperature to 400 °C, and the pressure is about 8.5 MPa. After the reaction system is stable, react for 1.5 h. Then take out the reactor and perform rapid cooling treatment. Centrifuge, wash, and dry the collected reaction system to obtain about 2.2 g of black nano-CuO powder.

[0027] Use the copper oxide prepared in the example as a catalyst for the glycerol conversion reaction. The catalytic steps are as follows: Weigh 0.6 g of CuO metal oxide catalyst and load it to the bottom of a batch reactor (inner lining volume: 100 mL). Among them, the glycerol aqueous solution is 10%, and the molar ratio of NaOH to glycerol is 1.5:1. React in a batch reactor at 190 °C for 5 hours. After cooling to room temperature, obtain the supernatant and catalyst powder. Take the supernatant and perform performance testing by liquid chromatography. The catalytic results are shown in Table 1. Example 7

[0028] Weigh 2.5 g of copper acetate and dissolve it in an appropriate amount of ethylene glycol to form a solution. Slowly add sodium hydroxide solution drop by drop to adjust the pH of the solution to 10 to form a slurry. Stir to make the system mix evenly, which is called the precursor. Add the precursor slurry into a high-pressure reactor, adjust the reaction temperature to 300 °C, and the pressure is about 7.0 MPa. After the reaction system is stable, react for 0.5 h. Then take out the reactor and perform rapid cooling treatment. Centrifuge, wash, and dry the collected reaction system to obtain about 1.6 g of black nano-CuO powder.

[0029] Use the copper oxide prepared in the example as a catalyst for the glycerol conversion reaction. The catalytic steps are as follows: Weigh 2.0 g of CuO metal oxide catalyst and load it to the bottom of a batch reactor (inner lining volume: 100 mL). Among them, the glycerol aqueous solution is 15%, and the molar ratio of NaOH to glycerol is 2:1. React in a batch reactor at 170 °C for 8 hours. After cooling to room temperature, obtain the supernatant and catalyst powder. Take the supernatant and perform performance testing by liquid chromatography. The catalytic results are shown in Table 1.

[0030] Table 1 Glycerol conversion rate (%) Lactic acid selectivity (%) Lactic acid yield (%) Example 1 86 52 45 Example 2 88 65 57 Example 3 95 83 79 Example 4 96 89 85 Example 5 81 77 62 Example 6 90 59 53 Example 7 95 57 48 .

Claims

1. A method for preparing multi-morphology copper oxide nano powder, characterized in that, The specific preparation steps of the method are as follows: First, a copper salt is used as a raw material and mixed evenly with an alkali metal precipitant to form a slurry. The solvent is added to a high-pressure reactor. After the reactor is sealed, the temperature is then heated to 100 - 500 °C and stirred to keep the reaction pressure at 0.1 - 20.0 MPa. The reaction is carried out for 0.05 - 3.0 h in this state, and then the reactor is cooled to room temperature. The mixed solution is centrifuged, washed, and vacuum dried to obtain nano-sized copper oxide powder; The copper salt is one or more of soluble copper salts such as copper nitrate, copper sulfate, copper acetate, and copper chloride, including but not limited to one or more mentioned in the examples; The alkaline precipitant is one or more of sodium carbonate, sodium bicarbonate, sodium phosphate, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, triethylamine, ammonia water, ammonium sulfate, and urea; The reaction medium is one or more of water and C1 - C4 organic alcohols; The concentration of the copper salt precursor in the reaction medium is 0.1 - 2.0 M.

2. The preparation method of a multi-morphology copper oxide nano powder according to claim 1, wherein, The prepared nano-sized copper oxide has nano-sized CuO crystals in the shapes of chrysanthemum, rod, hexahedron particle, polygonal coral edge block, pyramid sheet, and chrysanthemum sheet.

3. The preparation method of a multi-morphology copper oxide nano powder according to claim 1, characterized in that, The particle size range of the prepared nano-sized copper oxide powder is 5 - 50 nm.

4. A method for applying a multi-morphology copper oxide nano powder, characterized in that, The prepared multi-morphology copper oxide nano-powder is used as a catalyst for the glycerol conversion reaction. The steps are as follows: Weigh copper oxide (0.5 - 2.0 g) and load it to the bottom of a batch reactor. Mix and react according to NaOH : glycerol aqueous solution (10 - 20 w%) = 0.5 - 2 : 1 (molar ratio). The reaction temperature is controlled at 170 - 220 °C, and the reaction time is controlled at 0.5 - 8 h. After the reaction reaches equilibrium, it is cooled to room temperature, and the liquid-phase product is collected and analyzed qualitatively and quantitatively by liquid chromatography.

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