A method for preparing nano-oxide powder by solid-phase hot injection

Abstract

The application discloses a method for preparing nano-oxide powder by solid-phase hot injection, and utilizes inorganic metal salt and organic ligand to prepare metal-organic complex as metal precursor; under inert atmosphere, a synthesis solvent is heated, then the metal precursor is directly added in solid form, heat preservation reaction is carried out, and the organic ligand is recovered; the polar solvent is added into the mixed solution after heat preservation reaction, solid-liquid separation is carried out to obtain solid-phase product and liquid-phase mixed solvent; the nano-oxide powder is obtained by calcining the solid-phase product, and the synthesis solvent and the polar solvent are recovered by separating the liquid-phase mixed solvent. By the solid-phase hot injection, the same amount of synthesis solvent can be converted into more precursor to corresponding high-quality nano-particles without incomplete nucleation or particle agglomeration, the recovery rate of the organic ligand can be adjusted by selecting the synthesis solvent, and the synthesis solvent and the polar solvent in the solution after reaction are recycled.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials technology and relates to a method for preparing nano-oxide powders by solid-phase thermal injection. Background Technology

[0002] The synthesis of nanomaterials with significant physicochemical properties in organic phases has long been a focus of attention. Generally, the conventional method involves the chemical transformation of precursors in high-boiling-point organic solvents, followed by the addition of an excess of antisolvent (i.e., a polar solvent) to separate the resulting nanomaterials. Compared to co-precipitation or impregnation methods, organic phase synthesis offers significant advantages in terms of nanomaterial composition control, size and morphology regulation, particle uniformity and reproducibility, and preparation efficiency. However, organic phase synthesis of nanomaterials has not yet achieved widespread industrial application, primarily due to cost and scale-up issues. Regarding cost, organic phase synthesis relies on specific organometallic or metal-organic complexes, such as metal carbonyl complexes, metal acetylacetonate salts, and metal-oleic acid complexes, which are far more expensive than inorganic metal salts. Furthermore, during the synthesis and separation process, large quantities of long-chain synthesis solvents, detergents, and polar solvents are discarded rather than recycled, resulting in excessively high production costs for organic phase synthesis. In addition, the yields of conventional organic phase synthesis methods are only at the milligram or gram level, far below the requirements for industrial applications. Summary of the Invention

[0003] To address the technical problems existing in the preparation of nano-oxide powders, the present invention aims to provide a method for preparing nano-oxide powders using a solid-phase thermal injection method. This method allows for the conversion of more precursors into corresponding high-quality nanoparticles (with uniform particle purity) using the same amount of synthetic solvent without incomplete nucleation or particle agglomeration. Furthermore, the recovery rate of organic ligands can be controlled by selecting the synthetic solvent, which can be recycled for the synthesis of metal-organic complex precursors. Additionally, the synthetic solvent and polar solvent in the reaction solution can be recovered and reused, significantly reducing production costs.

[0004] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0005] A method for preparing nano-oxide powder using a solid-phase thermal injection method includes the following steps:

[0006] (1) Use inorganic metal salts and organic ligands to prepare metal-organic complexes as metal precursors;

[0007] (2) Under an inert atmosphere, the synthesis solvent is heated, and then the metal precursor is added directly in solid form. The reaction is kept at a constant temperature and the organic ligand is recovered.

[0008] (3) Add a polar solvent to the mixed solution after the heat preservation reaction, and then separate the solid phase product and the liquid phase mixed solvent to obtain the solid phase product and the liquid phase mixed solvent.

[0009] (4) The solid product is calcined to obtain nano-oxide powder, and the liquid mixed solvent is separated and recovered to obtain synthetic solvent and polar solvent.

[0010] In step (1) above, the inorganic metal salt is selected from one of the chloride, sulfate and nitrate salts of metals, and the inorganic metal is selected from at least one of the transition metals in the 4th to 6th periods, such as Cu, Fe, Co, Ni, Zr, Zn, Ce, Mn, etc.

[0011] In step (1) above, the organic ligand is acetylacetone.

[0012] In step (2) above, the inert atmosphere is a nitrogen, argon or helium atmosphere.

[0013] In step (2) above, the synthetic solvent is selected from at least one of ODE (octadecene), OAm (oleylamine), OA (oleic acid), and ODL (octadecyl alcohol); more preferably, it is a combination of ODE (1-octadecene) and OA (oleic acid).

[0014] In step (2) above, the heating temperature and the heat preservation reaction temperature are both 220-300℃.

[0015] In step (3) above, the polar solvent is selected from at least one of ethanol, methanol, and acetone.

[0016] In step (4) above, the calcination temperature is 400-800℃.

[0017] In step (4) above, the separation and recovery method is rotary evaporation, and the temperature is 70-120℃.

[0018] Compared with the prior art, the present invention has the following superior effects:

[0019] 1. This invention prepares metal-organic complex precursors suitable for the synthesis of nanoparticles in organic phases using inexpensive inorganic metal salts and organic ligands. At the same time, high-cost organic ligands are collected during the synthesis process, and the recovered organic ligands can be recycled for the synthesis of precursors.

[0020] 2. This invention uses a solid-phase thermal injection method, which allows the same amount of synthesis solvent to convert more precursors into corresponding high-quality nanoparticles (with uniform particle purity) without incomplete nucleation or particle agglomeration, thus facilitating the large-scale preparation of nanoparticles.

[0021] 3. This invention can effectively control the recovery of organic ligands by selecting the synthesis solvent, especially the combination of ODE and OA, which can greatly improve the recovery rate of organic ligands.

[0022] 4. This invention can recover large quantities of synthetic solvents and polar solvents by separating liquid-phase mixed solvents. Attached Figure Description

[0023] Figure 1 This diagram illustrates the synthesis of CuO nanoparticles and the recycling of the organic ligand (Hacac), synthesis solvent (ODE / OA), and polar solvent (EtOH) in Example 1 of this invention (the calcination process is not shown in the diagram), as well as the recovery rate and yield of each substance in each synthesis step.

[0024] Figure 2 The transmission electron microscope (TEM) images (ab), size distribution map (cd), and X-ray diffraction (XRD) spectra (ef) of CuO nanoparticles before and after calcination in Example 1 of this invention are shown. Before calcination, the nanoparticles are Cu nanoparticles with a size of approximately 24.8 nm, and after calcination, the nanoparticles are CuO nanoparticles with a size of approximately 46.1 nm.

[0025] Figure 3 The images shown are TEM images (ab), size distribution map (cd), and XRD patterns (ef) of the sample before and after calcination in Example 2, where a and c are before calcination, and b and d are after calcination.

[0026] Figure 4 The images shown are TEM images (ab) before and after calcination, particle size distribution (c) after calcination, and XRD pattern (d) of the sample in Example 3, where a is before calcination and b is after calcination.

[0027] Figure 5 The images shown are TEM images (a and c), particle size distribution map (b) and XRD spectrum (de) of the sample before and after calcination in Example 4, where a is before calcination and c is after calcination.

[0028] Figure 6 The images shown are TEM and XRD patterns of the sample before and after calcination in Example 5, where a represents the sample before calcination and b represents the sample after calcination.

[0029] Figure 7 The images shown are TEM images (ab), particle size distribution map (cd), and XRD spectrum (e) of the sample before and after calcination in Example 6, where a and c are before calcination, and b and d are after calcination.

[0030] Figure 8 The images shown are TEM and XRD patterns of the sample before and after calcination in Example 7, where a is before calcination and b is after calcination.

[0031] Figure 9 The images shown are TEM images (ab), particle size distribution map (cd), and XRD spectrum (e) of the sample before and after calcination in Example 8, where a and c are before calcination, and b and d are after calcination.

[0032] Figure 10 The yield, ODE recovery rate, and Hacac recovery rate of the corresponding nanopowders in Examples 2-8 are given.

[0033] Figure 11 The recovery rate of anhydrous ethanol during the preparation of the corresponding nanopowders in Examples 2-4 and 8 is given.

[0034] Figure 12 This document presents the characterization of the 4.5% CuO / ZnO / ZrO2 sample (4.5% CuO / ZnO / ZrO2-1) prepared in the first round of Example 9, a schematic diagram of solvent recycling, and the yield of multi-metal nano-oxides and the recovery rates of ODE and ethanol in each preparation round. Image a shows the TEM characterization of the 4.5% CuO / ZnO / ZrO2-1 sample; image b shows the high-resolution TEM image of the 4.5% CuO / ZnO / ZrO2-1 sample. , 0.294 nm interplanar spacing corresponds to the (101) crystal plane of ZrO2; c is the high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image and STEM energy-dispersive X-ray (EDX) elemental spectrum image of 4.5%-CuO / ZnO / ZrO2-1; d is a schematic diagram of solvent recycling; e is the yield of 4.5%-CuO / ZnO / ZrO2 in rounds 1-5 and the recovery rate of ODE and Hacac during the preparation process.

[0035] Figure 13 The recovery rate of anhydrous ethanol during the preparation of 4.5% CuO / ZnO / ZrO2 in rounds 1-5 of Example 9 is given.

[0036] Figure 14 TEM images of the 4.5% CuO / ZnO / ZrO2 samples prepared in rounds 2-5 (a, b, c, d, respectively) of Example 9.

[0037] Figure 15 The XRD patterns of the 4.5% CuO / ZnO / ZrO2 samples prepared in rounds 1-5 of Example 9 are shown. The XRD indicates that the crystal structure of 4.5% CuO / ZnO / ZrO2 is mainly tetragonal ZrO2 (PDF#88-1007). The diffraction peaks of the ZnO phase were not observed, possibly due to the formation of a ZnO / ZrO2 solid solution.

[0038] Figure 16 The images show the TEM image (a) and XRD pattern (b) of the Cu particles in Comparative Example 1.

[0039] Figure 17 TEM images of Cu (nanoparticles) in Comparative Examples 2(b), 3(a), and 4(c).

[0040] Figure 18 The image shown is a TEM image of the sample synthesized using the liquid-phase injection method in Comparative Example 5.

[0041] Figure 19 This is a TEM image of the Cu particles prepared in Comparative Example 6.

[0042] Figure 20 The recovery rates of Hacac were calculated under different synthesis solvents and without N2 flow. Detailed Implementation

[0043] The present invention will be further illustrated below with reference to specific embodiments. It should be noted that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Improvements and adjustments made by those skilled in the art based on the present invention in practical applications shall still fall within the scope of protection of the present invention.

[0044] Example 1

[0045] This embodiment describes the preparation of nano-CuO powder, and the steps are as follows:

[0046] Synthesize 50g of copper acetylacetone (Cu(acac)2) using CuSO4·5H2O:

[0047] (1) At room temperature, take 47.75g CuSO4·5H2O and place it in a 500mL flask. Add 200mL of ultrapure water and stir magnetically for 10min to form a homogeneous solution.

[0048] (2) Under ice bath conditions, add 41 mL of acetylacetone (Hacac) to the above solution and stir for 30 min. Then, inject 100 mL of 3.82 M NaOH solution into the above mixture at a rate of 3 mL / min to neutralize the generated H2SO4.

[0049] (3) The collected solid was immersed in ultrapure water for 30 min to remove the generated Na2SO4, and then the product was washed and collected by a vacuum filtration device. This process was repeated three times to remove impurities. Finally, the obtained powder was vacuum dried at 80 °C for 12 h to obtain high-purity Cu(acac)2.

[0050] Synthesize CuO nanoparticles and recover organic ligands, synthesis solvents, and polar solvents:

[0051] (1) Connect the 250mL four-necked flask to the straight condenser and the 250mL single-necked flask containing 200mL of ultrapure water in an orderly manner (wherein, the four necks of the four-necked flask are respectively connected to the heating mantle temperature probe). Figure 1 (Not shown in the text), N2 inlet, solid sampler, and straight condenser. The end of the straight condenser is connected to a single-necked flask containing ultrapure water for collecting Hacac. Mix 120 mL LODE and 30 mL OA in a 250 mL four-necked flask, then stir and heat it to 260 °C under N2 atmosphere on a heating mantle and hold for 10 min.

[0052] (2) Add 30g of Cu(acac)2 solid to the above high temperature solution at a rate of about 1.5g / min, and then keep the mixture at 260℃ for 20min;

[0053] (3) After cooling to room temperature, add 800 mL of anhydrous ethanol and centrifuge at 12000 rpm for 20 min to separate the solid; calcine the obtained solid in a muffle furnace at 500 °C for 1 h to remove the residual organic solvent, and finally obtain CuO nanoparticles.

[0054] (4) Use a laboratory rotary evaporator to distill the centrifuged liquid at 90°C to separate the synthetic solvent and ethanol.

[0055] Example 2

[0056] This embodiment describes the preparation of nano-Fe2O3 powder, and the steps are as follows:

[0057] Synthesize 50g of iron acetylacetone (Fe(acac)3) using FeCl3·6H2O:

[0058] (1) At room temperature, take 38.27g FeCl3·6H2O and place it in a 500mL flask. Add 200mL of ultrapure water and stir magnetically for 10min to form a homogeneous solution.

[0059] (2) Under ice bath conditions, add 45 mL of Hacac to the above solution and stir for 30 min. Then, inject 100 mL of 4.25 M NaOH solution into the above mixture at a rate of 3 mL / min to neutralize the generated HCl.

[0060] (3) The collected solid was immersed in ultrapure water for 30 min to remove the generated NaCl, and then the product was washed and collected by a vacuum filtration device. This process was repeated three times to remove impurities. Finally, the obtained powder was vacuum dried at 80 °C for 12 h to obtain high-purity Fe(acac)3.

[0061] Synthesis of Fe2O3 nanoparticles and recovery of organic ligands, synthesis solvents, and polar solvents:

[0062] (1) Connect a 250mL four-necked flask to a straight condenser and a 250mL single-necked flask containing 200mL of ultrapure water in an orderly manner. Mix 120mL of ODE and 30mL of OA in the 250mL four-necked flask, and then heat it to 260℃ under N2 atmosphere and keep it at that temperature for 10min;

[0063] (2) Add 30g of Fe(acac)3 solid to the above high temperature solution at a rate of about 1.5g / min, and then keep the mixture at 260℃ for 20min;

[0064] (3) After cooling to room temperature, add 800 mL of anhydrous ethanol and centrifuge at 12000 rpm for 20 min to separate the solid. Calcine the obtained solid in a muffle furnace at 500 °C for 1 h to remove residual organic solvent, and finally obtain Fe2O3 nanoparticles.

[0065] (4) Use a laboratory rotary evaporator to distill the centrifuged liquid at 90°C to separate the synthetic solvent and ethanol.

[0066] Example 3

[0067] This embodiment describes the preparation of nano-Co3O4 powder, and the steps are as follows:

[0068] Synthesize 50g of cobalt acetylacetone (Co(acac)2) using CoCl2·6H2O:

[0069] (1) At room temperature, take 46.26g of CoCl2·6H2O and place it in a 500mL flask. Add 200mL of ultrapure water and stir magnetically for 10min to form a homogeneous solution.

[0070] (2) Under ice bath conditions, add 41 mL of Hacac to the above solution and stir for 30 min. Then, inject 100 mL of 3.89 M NaOH solution into the above mixture at a rate of 3 mL / min to neutralize the generated HCl.

[0071] (3) The collected solid was immersed in ultrapure water for 30 min to remove the generated NaCl, and then the product was washed and collected by a vacuum filtration device. This process was repeated three times to remove impurities. Finally, the obtained powder was vacuum dried at 80 °C for 12 h to obtain high-purity Co(acac)2.

[0072] Synthesize Co3O4 nanoparticles and recover organic ligands, synthesis solvents, and polar solvents:

[0073] (1) Connect a 250mL four-necked flask to a straight condenser and a 250mL single-necked flask containing 200mL of ultrapure water in an orderly manner. Mix 120mL of ODE and 30mL of OA in the 250mL four-necked flask, and then heat it to 260℃ under N2 atmosphere and keep it at that temperature for 10min;

[0074] (2) Add 30g of Co(acac)2 solid to the above high temperature solution at a rate of about 1.5g / min, and then keep the mixture at 260℃ for 20min;

[0075] (3) After cooling to room temperature, add 800 mL of anhydrous ethanol and centrifuge at 12000 rpm for 20 min to separate the solid. Calcine the obtained solid in a muffle furnace at 500 °C for 1 h to remove the residual organic solvent, and finally obtain Co3O4 nanoparticles.

[0076] (4) Use a laboratory rotary evaporator to distill the centrifuged liquid at 90°C to separate the synthetic solvent and ethanol.

[0077] Example 4

[0078] This embodiment is based on nano-NiO. x The preparation of the powder involves the following steps:

[0079] Synthesize 50g of nickel acetylacetone (Ni(acac)2) using NiCl2·6H2O:

[0080] (1) At room temperature, take 46.26g NiCl2·6H2O and place it in a 500mL flask. Add 200mL of ultrapure water and stir magnetically for 10min to form a homogeneous solution.

[0081] (2) Under ice bath conditions, add 41 mL of Hacac to the above solution and stir for 30 min. Then, inject 100 mL of 3.89 M NaOH solution into the above mixture at a rate of 3 mL / min to neutralize the generated HCl.

[0082] (3) The collected solid was immersed in ultrapure water for 30 min to remove the generated NaCl, and then the product was washed and collected by a vacuum filtration device. This process was repeated three times to remove impurities. Finally, the obtained powder was vacuum dried at 80 °C for 12 h to obtain high-purity Ni(acac)2.

[0083] Synthesis of NiO x Nanoparticles and recovery of organic ligands, synthetic solvents, and polar solvents:

[0084] (1) Connect a 250mL four-necked flask to a straight condenser and a 250mL single-necked flask containing 200mL of ultrapure water in an orderly manner. Mix 120mL of ODE and 30mL of OA in the 250mL four-necked flask, and then heat it to 260℃ under N2 atmosphere and keep it at that temperature for 10min;

[0085] (2) Add 30g of Ni(acac)2 solid to the above high temperature solution at a rate of about 1.5g / min, and then keep the mixture at 260℃ for 20min;

[0086] (3) After cooling to room temperature, add 800 mL of anhydrous ethanol and centrifuge at 12000 rpm for 20 min to separate the solid; calcine the obtained solid in a muffle furnace at 500 °C for 1 h to remove residual organic solvent, finally obtaining NiO. x Nanoparticles;

[0087] (4) Use a laboratory rotary evaporator to distill the centrifuged liquid at 90°C to separate the synthetic solvent and ethanol.

[0088] Example 5

[0089] This embodiment describes the preparation of nano-ZrO2 powder, and the steps are as follows:

[0090] 50g of zirconium acetylacetonate (Zr(acac)4) was synthesized using ZrOCl2·8H2O:

[0091] (1) At room temperature, take 33.04g ZrOCl2·8H2O and place it in a 500mL flask. Add 200mL of ultrapure water and stir magnetically for 10min to form a homogeneous solution.

[0092] (2) Under ice bath conditions, add 43 mL of Hacac to the above solution and stir for 30 min. Then, inject 100 mL of 4.10 M NaOH solution into the above mixture at a rate of 3 mL / min to neutralize the generated HCl.

[0093] (3) The collected solid was immersed in ultrapure water for 30 min to remove the generated NaCl, and then the product was washed and collected by a vacuum filtration device. This process was repeated three times to remove impurities. Finally, the obtained powder was vacuum dried at 80 °C for 12 h to obtain high-purity Zr(acac)4.

[0094] Synthesis of ZrO2 nanoparticles and recovery of organic ligands, synthesis solvents, and polar solvents:

[0095] (1) Connect a 250mL four-necked flask to a straight condenser and a 250mL single-necked flask containing 200mL of ultrapure water in an orderly manner. In the 250mL four-necked flask, heat 150mL of ODE to 260℃ under a N2 atmosphere and keep warm for 10min;

[0096] (2) Add 30g of Zr(acac)4 solid to the above high temperature solution at a rate of about 1.5g / min, and then keep the mixture at 250℃ for 20min;

[0097] (3) After cooling to room temperature, centrifuge at 12000 rpm for 20 min to separate the solid; calcine the obtained solid in a muffle furnace at 500℃ for 1 h to remove the residual organic solvent, and finally obtain ZrO2 nanoparticles.

[0098] (4) Use a laboratory rotary evaporator to distill the centrifuged liquid at 90°C to separate the synthetic solvent and ethanol.

[0099] The calcined ZrO2 powder consists of a tetragonal ZrO2 phase (PDF#88-1007) and a monoclinic ZrO2 phase (circled). Figure 6 c).

[0100] Example 6

[0101] This embodiment describes the preparation of nano-ZnO powder, and the steps are as follows:

[0102] Synthesize 50g of zinc acetylacetonate (Zn(acac)2) using ZnCl2:

[0103] (1) At room temperature, take 25.85g of ZnCl2 and place it in a 500mL flask. Add 200mL of ultrapure water and stir magnetically for 10min to form a homogeneous solution.

[0104] (2) Under ice bath conditions, add 40 mL of Hacac to the above solution and stir for 30 min. Then, inject 100 mL of 3.79 M NaOH solution into the above mixture at a rate of 3 mL / min to neutralize the generated HCl.

[0105] (3) The collected solid was immersed in ultrapure water for 30 min to remove the generated NaCl, and then the product was washed and collected by a vacuum filtration device. This process was repeated three times to remove impurities. Finally, the obtained powder was vacuum dried at 40 °C for 12 h to obtain high-purity Zn(acac)2.

[0106] Synthesize ZnO nanoparticles and recover organic ligands, synthesis solvents, and polar solvents:

[0107] (1) Connect a 250mL four-necked flask to a straight condenser and a 250mL single-necked flask containing 200mL of ultrapure water in an orderly manner. In the 250mL four-necked flask, heat 150mL of ODE to 260℃ under a N2 atmosphere and keep warm for 10min;

[0108] (2) Add 30g of Zn(acac)2 solid to the above high temperature solution at a rate of about 1.5g / min, and then keep the mixture at 250℃ for 20min;

[0109] (3) After cooling to room temperature, centrifuge at 12000 rpm for 20 min to separate the solid; calcine the obtained solid in a muffle furnace at 400℃ for 1 h to remove the residual organic solvent, and finally obtain ZnO nanoparticles;

[0110] (4) Use a laboratory rotary evaporator to distill the centrifuged liquid at 90°C to separate the synthetic solvent and ethanol.

[0111] Example 7

[0112] This embodiment describes the preparation of nano-CeO2 powder, and the steps are as follows:

[0113] 50g of cerium acetylacetone (Ce(acac)3) was synthesized using CeCl3·7H2O:

[0114] (1) At room temperature, take 42.59g NiCl2·6H2O and place it in a 500mL flask. Add 200mL of ultrapure water and stir magnetically for 10min to form a homogeneous solution.

[0115] (2) Under ice bath conditions, add 36 mL of Hacac to the above solution and stir for 30 min. Then, inject 100 mL of 3.43 M NaOH solution into the above mixture at a rate of 3 mL / min to neutralize the generated HCl.

[0116] (3) The collected solid was immersed in ultrapure water for 30 min to remove the generated NaCl, and then the product was washed and collected by vacuum filtration. This process was repeated three times to remove impurities. Finally, the obtained powder was vacuum dried at 80 °C for 12 h to obtain high-purity Ce(acac)3.

[0117] Synthesis of CeO2 nanoparticles and recovery of organic ligands, synthesis solvents, and polar solvents:

[0118] (1) Connect a 250mL four-necked flask to a straight condenser and a 250mL single-necked flask containing 200mL of ultrapure water in an orderly manner. Mix 120mL ODE, 12mL OA and 18mL OAm in the 250mL four-necked flask, and then heat it to 260℃ under N2 atmosphere with stirring, and keep it at that temperature for 10min;

[0119] (2) Add 30g of Ce(acac)3 solid to the above high temperature solution at a rate of about 1.5g / min, and then keep the mixture at 260℃ for 20min;

[0120] (3) After cooling to room temperature, centrifuge at 12000 rpm for 20 min to separate the solid; calcine the obtained solid in a muffle furnace at 400℃ for 1 h to remove the residual organic solvent, and finally obtain CeO2 nanoparticles.

[0121] (4) Use a laboratory rotary evaporator to distill the centrifuged liquid at 90°C to separate the synthetic solvent and ethanol.

[0122] Example 8

[0123] This embodiment describes the preparation of nano-Mn3O4 powder, and the steps are as follows:

[0124] Synthesize 50g of manganese acetylacetone (Mn(acac)2) using MnSO4·H2O:

[0125] (1) At room temperature, take 33.38g of MnSO4·H2O and place it in a 500mL flask. Add 200mL of ultrapure water and stir magnetically for 10min to form a homogeneous solution.

[0126] (2) Under ice bath conditions, add 42 mL of Hacac to the above solution and stir for 30 min. Then, inject 100 mL of 3.95 M NaOH solution into the above mixture at a rate of 3 mL / min to neutralize the generated H2SO4.

[0127] (3) The collected solid was immersed in ultrapure water for 30 min to remove the generated Na2SO4, and then the product was washed and collected by a vacuum filtration device. This process was repeated three times to remove impurities. Finally, the obtained powder was vacuum dried at 80 °C for 12 h to obtain high-purity Mn(acac)2.

[0128] Synthesis of Mn3O4 nanoparticles and recovery of organic ligands, synthesis solvents, and polar solvents:

[0129] (1) Connect a 250mL four-necked flask to a straight condenser and a 250mL single-necked flask containing 200mL of ultrapure water in an orderly manner. Mix 120mL of ODE and 30mL of OA in the 250mL four-necked flask, and then heat it to 260℃ under N2 atmosphere and keep it at that temperature for 10min;

[0130] (2) Add 30g of Mn(acac)2 solid to the above high temperature solution at a rate of about 1.5g / min, and then keep the mixture at 260℃ for 20min;

[0131] (3) After cooling to room temperature, add 800 mL of anhydrous ethanol and centrifuge at 12000 rpm for 20 min to separate the solid. Calcine the obtained solid in a muffle furnace at 400 °C for 1 h to remove the residual organic solvent and finally obtain Mn3O4 nanoparticles.

[0132] (4) Use a laboratory rotary evaporator to distill the centrifuged liquid at 90°C to separate the synthetic solvent and ethanol.

[0133] Example 9

[0134] This example describes the preparation of a 4.5% CuO / ZnO / ZrO2 (CuO molar fraction is 4.5%) polymetallic oxide, and the steps are as follows:

[0135] Preparation of 4.5% CuO / ZnO / ZrO2 polymetallic oxides:

[0136] (1) Connect a 250mL four-necked flask to a straight condenser and a 250mL single-necked flask containing 200mL of ultrapure water in an orderly manner. Mix 140mL of ODE and 10mL of OA in the 250mL four-necked flask, and then stir and heat it to 260℃ under N2 atmosphere, and keep it at that temperature for 10min;

[0137] (2) 2.19g Zn(acac)2 and 27.05g Zr(acac)4 were mixed evenly and added to the above high temperature solution at a rate of about 1.5g / min. The mixture was then kept at 260℃ for 20min.

[0138] (3) After cooling to room temperature, add 0.79g Cu(acac)2, keep warm at 120℃ for 10min, and then slowly raise the temperature to 260℃ and keep warm for 20min.

[0139] (4) After the above mixed solution is cooled to room temperature, 800 mL of anhydrous ethanol is added to it, and the solid is separated by centrifugation at 12000 rpm for 20 min. The obtained solid is calcined in a muffle furnace at 500 °C for 3 h to remove the residual organic solvent, and finally 4.5% CuO / ZnO / ZrO2 nanoparticles are obtained.

[0140] (5) Use a laboratory rotary evaporator to distill the centrifuged liquid at 90°C to separate the synthetic solvent and ethanol.

[0141] 4.5% CuO / ZnO / ZrO2 was prepared by recycling the recovered solvent.

[0142] (1) The purity of ODE and anhydrous ethanol was determined by gas chromatography to determine the recovery rate and the amount of solvent to be added in the next synthesis.

[0143] (2) Prepare 4.5% CuO / ZnO / ZrO2 according to the original procedure, and replenish the corresponding solvents before the next synthesis process (as shown in Table 1). All solvents were recovered and reused four times. It should be noted that OA is almost consumed in the reaction process, so 10 mL of new OA is added before each round of reaction, while the corresponding amount of ODE is added only in the first and fourth rounds to ensure that the total volume of the solution is 150 mL during synthesis.

[0144] Table 1. Solvent recovered and replenished in each round of the cyclic preparation of 4.5% CuO / ZnO / ZrO2.

[0145]

[0146] Comparative Example 1

[0147] Synthesizing Cu particles using ODE as a solvent and recovering organic ligands:

[0148] (1) Connect a 250mL four-necked flask to a straight condenser and a 250mL single-necked flask containing 200mL of ultrapure water in an orderly manner. Add 150mL of ODE to the 250mL four-necked flask, and then heat it to 260℃ under N2 atmosphere with stirring, and keep it at that temperature for 10min;

[0149] (2) Add 30g of Cu(acac)2 solid to the above high temperature solution at a rate of about 1.5g / min, and then keep the mixture at 260℃ for 20min;

[0150] (3) After cooling to room temperature, add 800 mL of anhydrous ethanol and centrifuge at 12000 rpm for 20 min to separate the solid and obtain Cu particles.

[0151] like Figure 16 As shown, when using ODE as the solvent alone, it is impossible to control the particle size and morphology, resulting in Cu particles of varying shapes with sizes ranging from 0.2 to 1 μm.

[0152] Comparative Example 2

[0153] ODE / OAm as solvent for Cu particle synthesis:

[0154] (1) Connect a 250mL four-necked flask to a straight condenser and a 250mL single-necked flask containing 200mL of ultrapure water in an orderly manner. Mix 120mL of ODE and 30mL of OAm in the 250mL four-necked flask, and then heat it to 260℃ under N2 atmosphere and keep it at that temperature for 10min;

[0155] (2) Add 30g of Cu(acac)2 solid to the above high temperature solution at a rate of about 1.5g / min, and then keep the mixture at 260℃ for 20min;

[0156] (3) After cooling to room temperature, add 800 mL of anhydrous ethanol and centrifuge at 12000 rpm for 20 min to separate the solid and obtain Cu particles.

[0157] like Figure 17 As shown in (b) and 20, although uniformly sized Cu nanoparticles can be obtained when ODE / OAm is used as a solvent, the Hacac recovery rate decreases to 21.92%.

[0158] Comparative Example 3

[0159] ODE / ODL was used as a solvent to synthesize Cu particles and recover organic ligands:

[0160] (1) Connect a 250mL four-necked flask to a straight condenser and a 250mL single-necked flask containing 200mL of ultrapure water in an orderly manner. Mix 120mL of ODE and 30mL of ODL in the 250mL four-necked flask, and then stir and heat it to 260℃ under N2 atmosphere, and keep it at that temperature for 10min;

[0161] (2) Add 30g of Cu(acac)2 solid to the above high temperature solution at a rate of about 1.5g / min, and then keep the mixture at 260℃ for 20min;

[0162] (3) After cooling to room temperature, add 800 mL of anhydrous ethanol and centrifuge at 12000 rpm for 20 min to separate the solid and obtain Cu particles.

[0163] like Figure 17 As shown in (a) and 20, when ODE / ODL is used as a solvent, the Cu particle size cannot be effectively controlled, and the Hacac recovery rate drops to 10.7%.

[0164] Comparative Example 4

[0165] Cu particles were synthesized via injection using a combined heating method.

[0166] (1) Connect a 250mL four-necked flask to a straight condenser and a 250mL single-necked flask containing 200mL of ultrapure water in an orderly manner. Mix 120mL of ODE, 30mL of OAm and 30g of Cu(acac)2 solid in the 250mL four-necked flask, and then stir and heat it to 260℃ under N2 atmosphere and keep it at that temperature for 40min;

[0167] (3) After cooling to room temperature, add 800 mL of anhydrous ethanol and centrifuge at 12000 rpm for 20 min to separate the solid.

[0168] like Figure 17 As shown in (c), the mixed heating method causes Cu particles to agglomerate and grow.

[0169] Comparative Example 5

[0170] Liquid-phase injection synthesis of Cu particles:

[0171] (1) Connect a 250mL four-necked flask to a straight condenser and a 250mL single-necked flask containing 200mL of ultrapure water in an orderly manner. Add 150mL of OA to the 250mL four-necked flask, and then heat it to 260℃ under N2 atmosphere with stirring, and keep it at that temperature for 10min;

[0172] (2) Dissolve 30g of Cu(acac)2 solid in 50mL of Hacac and add it to the above high temperature solution at a rate of about 2mL / min. Then keep the mixture at 260℃ for 20min.

[0173] (3) After cooling to room temperature, add 800 mL of anhydrous ethanol and centrifuge at 12000 rpm for 20 min to separate the solid.

[0174] like Figure 18 As shown, when the precursor Cu(acac)2 is dissolved in Hacac for liquid phase injection, solvent splashing is likely to occur, and Cu particles cannot be obtained; only filamentous agglomerates are obtained.

[0175] Comparative Example 6

[0176] Synthesizing Cu particles using OA as a solvent and recovering organic ligands:

[0177] (1) Connect a 250mL four-necked flask to a straight condenser and a 250mL single-necked flask containing 200mL of ultrapure water in an orderly manner. Add 150mL of OA to the 250mL four-necked flask, and then heat it to 260℃ under N2 atmosphere with stirring, and keep it at that temperature for 10min;

[0178] (2) Add 30g of homemade Cu(acac)2 to the above high temperature solution at a rate of about 1.5g / min, and then keep the mixture at 260℃ for 20min;

[0179] (3) After cooling to room temperature, add 800 mL of anhydrous ethanol and centrifuge at 12000 rpm for 20 min to separate the solid and obtain Cu particles.

[0180] like Figure 19 As shown, when only OA is used as a solvent, the Cu particle size is approximately 200-500 nm.

[0181] Comparative Example 7

[0182] Synthesis of Cu particles under conditions without N2:

[0183] (1) Connect a 250mL four-necked flask to a straight condenser and a 250mL single-necked flask containing 200mL of ultrapure water in an orderly manner. Without passing N2, mix 120mL of ODE and 30mL of OA in the 250mL four-necked flask, and then heat it directly to 260℃ on a heating mantle with stirring, and keep it at that temperature for 10min;

[0184] (2) Add 30g of Cu(acac)2 solid to the above high temperature solution at a rate of about 1.5g / min, and then keep the mixture at 260℃ for 20min;

[0185] (3) After cooling to room temperature, add 800 mL of anhydrous ethanol and centrifuge at 12000 rpm for 20 min to separate the solid.

[0186] Figure 20 The recovery rates of haac under different synthesis solvents and without N2 were compared with those under conditions using only ODE as the synthesis solvent. The addition of OA promoted haac recovery, while the addition of OAM or ODL had a negative impact on haac recovery. Therefore, strictly limiting the synthesis solvent is crucial for more effective control of organic ligand (haac) recovery. The haac recovery rate under conditions without N2 was only 9.12%, demonstrating that aeration can effectively remove and recover the haac generated during synthesis.

Claims

1. A method for preparing nano-oxide powder using a solid-phase thermal injection method, characterized in that, Includes the following steps: (1) A metal-organic complex is prepared as a metal precursor using an inorganic metal salt and an organic ligand; wherein the inorganic metal is selected from at least one of Cu, Fe, Co, Ni, Zr, Zn, Ce, and Mn; and the organic ligand is acetylacetone. (2) Under an inert atmosphere, the synthesis solvent is heated, and then the metal precursor is added directly in solid form. The reaction is kept warm and the organic ligand is recovered. The synthesis solvent is selected from octadecene, or at least one of oleic acid, oleylamine, and octadecyl alcohol combined with octadecene. The heating temperature and the warming reaction temperature are both 220-300 °C. (3) Add a polar solvent to the mixed solution after the heat preservation reaction, and obtain a solid product and a liquid mixed solvent by solid-liquid separation; (4) The solid product is calcined to obtain nano-oxide powder, and the liquid mixed solvent is separated and recovered to obtain synthetic solvent and polar solvent.

2. The method for preparing nano-oxide powder using solid-phase thermal injection according to claim 1, characterized in that, In step (1), the inorganic metal salt is selected from one of the chloride, sulfate, and nitrate salts of metals.

3. The method for preparing nano-oxide powder using solid-phase thermal injection according to claim 1, characterized in that, In step (2), the inert atmosphere is a nitrogen, argon or helium atmosphere.

4. The method for preparing nano-oxide powder using solid-phase thermal injection according to claim 1, characterized in that, In step (2), the synthetic solvent is a combination of octadecene and oleic acid.

5. The method for preparing nano-oxide powder using solid-phase thermal injection according to claim 1, characterized in that, In step (3), the polar solvent is selected from at least one of ethanol, methanol, and acetone.

6. The method for preparing nano-oxide powder using solid-phase thermal injection according to claim 1, characterized in that, In step (4), the calcination temperature is 400-800 ℃; The separation and recovery method is rotary evaporation, with a temperature of 70-120 ℃.

Images