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CN-121974323-A - Preparation process and method of nano material

CN121974323ACN 121974323 ACN121974323 ACN 121974323ACN-121974323-A

Abstract

The invention discloses a preparation process and a preparation method of a nano material, in particular to a method for efficiently preparing lithium iron phosphate, composite sodium iron phosphate and calcium carbonate by a sol-gel method and a precipitation method. The preparation of lithium iron phosphate and composite sodium iron phosphate has controllable reaction process, controlled oscillating condition, reaction temperature, pH value and residence time, and calcination of gel to obtain target product, and the preparation of calcium carbonate has reinforced nucleation and crystallization by controlling the flow rate of precursor, precipitant and surfactant and combining oscillation. The method strengthens the mixed mass transfer by means of the periodic oscillating flow, inhibits local supersaturation and concentration gradient, reduces reactant deposition and channel blockage, ensures continuous and stable production, reduces the dosage and cost of the surfactant, and realizes accurate regulation and control of the particle size, morphology and distribution of the material. Compared with the traditional process, the preparation period is greatly shortened, the product purity and the reaction efficiency are improved, the method is suitable for industrial continuous production, and obvious economic and social benefits are achieved.

Inventors

  • YAN ZUOYI
  • WANG YIYING
  • ZHENG CHENGHUI
  • Shi Chengchun
  • HUANG JINGZHAO
  • CHEN JUNJUN
  • CHEN YUANFENG
  • ZHENG HUIDONG
  • GAO ZHIHAN

Assignees

  • 福州大学
  • 福建省环境科学研究院(福建省排污权储备和技术中心)

Dates

Publication Date
20260505
Application Date
20260310

Claims (10)

  1. 1. The preparation method of the nano lithium iron phosphate/composite sodium iron phosphate material is characterized by comprising the following steps: (1) Dissolving a lithium source or a sodium source and a phosphorus source in a solvent according to a molar ratio of (0.97-1.05): 1, adding a complexing agent and a carbon source, wherein the mass ratio of the complexing agent to the carbon source to metal ions is (0-2): 1, and uniformly stirring to obtain a precursor A solution; (2) Three feeds, namely a precursor A solution, a precursor B solution and ammonia water, are arranged in a microchannel reactor, the precursor A solution and the precursor B solution are injected at the same flow, mixed and reacted under a certain oscillating condition to obtain a mixed solution C, and the pH value of the mixed solution C is dynamically regulated to be between 4 and 8 by adopting the ammonia water; (3) And drying, grinding, sieving and calcining the gel precursor to obtain the nano lithium iron phosphate/composite sodium iron phosphate.
  2. 2. The preparation method of claim 1, wherein in the step (1), the lithium source is one of lithium carbonate, lithium acetate, lithium bicarbonate, lithium citrate, lithium phosphate or lithium nitrate, the iron source is one of ferric nitrate, ferric chloride, ferric citrate, ferrous acetate or ferric sulfate, the phosphorus source is one of monoammonium phosphate, diammonium phosphate or phosphoric acid, the sodium source is one or more of sodium carbonate, sodium acetate, sodium citrate or sodium dihydrogen phosphate, and the complexing agent and the carbon source are one or more of citric acid, oxalic acid, ethylenediamine tetraacetic acid, ethylene glycol, polyethylene glycol, glucose, sucrose or ascorbic acid.
  3. 3. The method according to claim 1, wherein the oscillation condition in the step (2) is oscillation frequency of 0.1-30Hz, oscillation amplitude of 0-110 mm, and the oscillation waveform is one of sine wave, square wave, triangular wave or pulse wave.
  4. 4. The method of claim 1, wherein the temperature in the step (2) is 80-120 ℃ and the residence time is 3-10 min.
  5. 5. The method according to claim 1, wherein the calcination in the step (3) is performed under nitrogen or argon atmosphere at 500 to 750 ℃ for 4 to 12 hours.
  6. 6. The nano lithium iron phosphate/composite sodium iron phosphate material prepared by the preparation method according to any one of claims 1-5, wherein the primary particle size of the nano lithium iron phosphate/composite sodium iron phosphate material is 30-180 nm, and the specific capacity is more than 90% of the theoretical capacity ratio.
  7. 7. A preparation method of calcium carbonate based on a precipitation method is characterized by comprising the following steps: (1) Respectively dissolving a calcium salt precursor and a precipitant in deionized water to prepare a precursor solution with the concentration of 0.01-2 mol/L and a precipitant solution with the concentration of 0.01-3 mol/L, and filtering for later use; (2) The precursor solution and the precipitant solution are introduced into a micro-channel reactor at the same flow, the reaction temperature is controlled at 25 ℃, the residence time is 0.1-60 s, and the reaction is carried out under the oscillation condition; (3) After the reaction is finished, collecting a product from an outlet, and obtaining the calcium carbonate through centrifugation, washing and drying.
  8. 8. The method according to claim 7, wherein the calcium salt precursor in the step (1) is at least one of calcium chloride, calcium nitrate and calcium hydroxide, and the precipitant is at least one of sodium carbonate, sodium hydroxide, potassium carbonate and sodium sulfate.
  9. 9. The method according to claim 7, wherein the oscillation condition in the step (2) is that the oscillation frequency f is 0 to 30Hz, the oscillation amplitude is 20 to 110 mm, and the oscillation waveform is a sine wave, a square wave, a triangular wave or a pulse wave.
  10. 10. The method of claim 7 to 9, wherein the calcium carbonate has a particle size of 30 to 120 nm, the crystal form of the particles is vaterite or calcite, the growth of the (110) crystal face is promoted when the oscillation frequency is controlled to 10 to 20 Hz, and the growth of the (104) crystal face is promoted when the oscillation frequency is controlled to 0 to 10 Hz and 20 to 30 Hz.

Description

Preparation process and method of nano material Technical Field The invention belongs to the technical field of chemical synthesis materials, and particularly relates to a preparation process and a preparation method of a nano material. Background In the field of modern chemical synthesis, the precise and controllable preparation of materials and the optimization of synthesis process are core research directions. Inorganic materials such as lithium iron phosphate (LiFePO 4), composite sodium iron phosphate (Na 4Fe3(PO4)2P2O7, NFPP) and calcium carbonate are widely used in the fields of energy storage, catalysis, environmental management and the like due to their excellent properties. The lithium iron phosphate, which is an important lithium ion battery anode material, has high energy density, long service life and good safety, and is widely applied to electric vehicles and energy storage equipment. The composite sodium iron phosphate gradually becomes an important component in the novel energy material due to good electrochemical performance and cost advantages. In addition, the shape-controllable calcium carbonate is also indispensable in environmental control and high-end composite materials. However, the preparation process of these materials has faced challenges of improving synthesis efficiency, controlling product quality, avoiding reactor blockage, and low safety. At present, the materials are mainly synthesized by a solid phase method and a hydrothermal method in industry, and rarely prepared by a sol-gel method or a coprecipitation method. Although the method can effectively prepare the target material, the method is difficult to realize industrialized application due to the problems of long preparation period, uneven product distribution, low product purity, equipment blockage and the like in the production process. Although the sol-gel method has better controllability and uniformity, the sol-gel method has the defects of long reaction time, high energy consumption, low mass and heat transfer efficiency and the like in the traditional batch reaction. While the precipitation method is used as another common preparation method, although a high-purity product can be obtained, stable production is often difficult to ensure due to uneven mixing of fluid in a reactor and lower mass transfer efficiency, and in addition, the preparation of a specific morphology depends on a special surfactant, so that the production cost is obviously increased. Although the traditional reaction kettle has certain advantages on the production scale, the problems of uneven macro mixing, poor heat transfer, inaccurate reaction time control and the like in the reaction kettle lead to poor batch stability of products, wide particle size distribution and difficulty in meeting the requirement of high-quality production. In order to overcome the above problems, the microchannel reactor is becoming an important tool in chemical synthesis due to its high specific surface area, excellent heat and mass transfer rate, and uniform residence time. Although the micro-channel reactor can provide ideal reaction conditions, the traditional micro-channel reactor still faces the problems of high-viscosity solid blocking channels and insufficient product regulation precision in the application process of preparing nano materials by a sol-gel method and a precipitation method. At present, some traditional anti-blocking technologies, such as surface modification and online ultrasonic cleaning, can solve the blocking problem to a certain extent, but have obvious limitations. For example, ultrasonic cleaning is easy to generate local cavitation high temperature, and the surface coating is easy to wear after long-time running, so that the anti-blocking effect is lost. Therefore, development of a novel, efficient and stable strategy is needed, and key problems of channel blockage, insufficient product regulation precision and the like of a micro-channel reactor in nano material synthesis are fundamentally solved. Disclosure of Invention The invention aims to provide a preparation process and a preparation method of a nano material, which are used for solving the problems of long reaction period, high energy consumption, reactor blockage, high cost and the like in the processes of preparing LiFePO 4 and NFPP by a sol-gel method and preparing calcium carbonate with specific morphology by a precipitation method, realizing the three-in-one of anti-blocking, controllable preparation and continuous and stable operation by combining a micro-channel reactor system of an oscillation coupling technology, improving the production efficiency and the product quality, and having important significance for promoting the industrialized production of materials such as lithium iron phosphate, NFPP and calcium carbonate. In order to achieve the above purpose, the invention adopts the following technical scheme: the invention provides a preparation method of a nano li