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CN-117800374-B - Method for synthesizing magnesium-aluminum hydrotalcite

CN117800374BCN 117800374 BCN117800374 BCN 117800374BCN-117800374-B

Abstract

The invention discloses a method for synthesizing magnesium aluminum hydrotalcite, which comprises the following steps of (1) mixing magnesium oxide, magnesium bicarbonate, aluminum hydroxide and sodium hydroxide, then adding an ethanol aqueous solution for wet grinding, (2) grinding while gradually heating, then carrying out heat preservation reaction, and (3) recovering to normal temperature after the reaction is finished, filtering, washing with water and drying to obtain the magnesium aluminum hydrotalcite. The magnesium aluminum hydrotalcite obtained by the invention has high crystallinity, smaller particle size, good particle size dispersibility, high purity, no impurity and high yield.

Inventors

  • GUO YONGWU
  • GUO JIAOYANG
  • ZHAO CHONGXIN

Assignees

  • 江苏极易新材料有限公司
  • 郭永武

Dates

Publication Date
20260505
Application Date
20240108

Claims (5)

  1. 1. The method for synthesizing the magnesium aluminum hydrotalcite is characterized by comprising the following steps of: (1) Mixing magnesium oxide, magnesium bicarbonate, aluminum hydroxide and sodium hydroxide, adding an ethanol aqueous solution for wetting and grinding for 20-30 min; (2) Continuously grinding, gradually heating to 75-85 ℃, and reacting for 1-1.5 h at a temperature; (3) Recovering to normal temperature after the reaction is finished, filtering, washing with water and drying to obtain magnesium aluminum hydrotalcite; The mass fraction of the ethanol aqueous solution is 70-80%; the magnesium oxide, the magnesium bicarbonate, the aluminum hydroxide and the sodium hydroxide are mixed according to the mol ratio of 2:1:1:3; in the step (1), the grinding rotating speed is 300-500 r/min; in the step (3), grinding the product in the drying process, wherein the grinding is carried out every 2-3 hours; in the step (2), the gradual heating rate is 0.5-1 ℃ per minute.
  2. 2. The method for synthesizing magnesium aluminum hydrotalcite according to claim 1, wherein in the step (1), the amount of the aqueous ethanol solution added is 1 to 2 times the weight of magnesium oxide.
  3. 3. The method for synthesizing magnesium aluminum hydrotalcite according to claim 1, wherein in the step (2), the grinding speed is 300-500 r/min.
  4. 4. The method for synthesizing the magnesium aluminum hydrotalcite according to claim 1, wherein in the step (3), water is washed for 2-3 times, and the amount of pure water is 2-3 times of that of an ethanol aqueous solution each time.
  5. 5. The method for synthesizing magnesium aluminum hydrotalcite according to claim 1, wherein in the step (3), the drying temperature is 90-100 ℃ for 6-8 hours.

Description

Method for synthesizing magnesium-aluminum hydrotalcite Technical Field The invention relates to a method for synthesizing magnesium aluminum hydrotalcite, and belongs to the technical field of hydrotalcite. Background Hydrotalcite-like compounds, also called layered double hydroxides, belong to anionic layered compounds, and typical hydrotalcite is magnesium aluminum carbonate hydrotalcite, has good heat stability, flame retardance, ultraviolet resistance and other properties, and is widely applied in the fields of plastics, rubber, glass and the like. The preparation method of the hydrotalcite compound comprises a coprecipitation method, an ion exchange method, a hydrothermal method, a roasting recovery method, a nucleation/crystallization separation method and the like, but the prior art has certain defects that in the coprecipitation method, nucleation and crystallization are carried out simultaneously, so that the particle size distribution range of a product is wider, the particle size is irregular, a large amount of byproducts and waste water are generated, the cost is high, the process is complex and tedious, time and labor are consumed in the ion exchange method, a large amount of waste water is generated in the hydrothermal method, the yield is small, high-temperature calcination is needed in the roasting recovery method, the equipment investment is large, the process is complex, the equipment needs to be specially manufactured, the complexity of the process is increased, the reaction concentration is required to be strictly controlled, the purity of hydrotalcite is greatly reduced due to the excessive concentration and the like. Disclosure of Invention At least aiming at the problems existing in the prior art, the invention provides a method for synthesizing magnesium aluminum hydrotalcite, which has the advantages of high crystallinity of the obtained magnesium aluminum hydrotalcite, small particle size, good particle size dispersibility, high purity, no impurity and high yield. In order to achieve the purpose, the invention adopts the following technical scheme that the method for synthesizing the magnesium aluminum hydrotalcite comprises the following steps: (1) Mixing magnesium oxide, magnesium bicarbonate, aluminum hydroxide and sodium hydroxide, adding an ethanol aqueous solution for wetting and grinding for 20-30 min; (2) Continuously grinding, gradually heating, and preserving heat to finish the reaction; (3) And (3) after the reaction is finished, recovering to normal temperature, filtering, washing with water and drying to obtain the magnesium aluminum hydrotalcite. Preferably, in the step (1), magnesium oxide, magnesium bicarbonate, aluminum hydroxide and sodium hydroxide are mixed according to a molar ratio of 2:1:1:3. Preferably, in the step (1), the addition amount of the ethanol aqueous solution is 1-2 times of the weight of the magnesium oxide. Preferably, in the step (1), the mass fraction of the ethanol aqueous solution is 70-80%, and the particle size uniformity of the product is improved during grinding. Preferably, in the step (1) and the step (2), the grinding rotation speed is 300-500 r/min. Preferably, in the step (2), the temperature is gradually increased to 75-85 ℃, and the reaction is carried out for 1-1.5 h at a constant temperature. In the step (2), the gradual heating rate is 0.5-1 ℃ per minute. Preferably, in the step (3), the water is washed for 2 to 3 times, and the pure water consumption is 2 to 3 times of that of the ethanol water solution each time. Preferably, in the step (3), the drying temperature is 90-100 ℃ and is 6-8 hours. Preferably, in the step (3), the product is ground in the drying process, and the grinding is carried out every 2-3 hours, so that the drying agglomeration is avoided, the crystallinity of the product is improved, and meanwhile, the particle size uniformity of the product is further improved. Preferably, in step (1), the purity of the magnesium oxide is not less than 98%. Preferably, in step (1), the purity of the magnesium bicarbonate is not less than 98%. Preferably, in step (1), the purity of the aluminum hydroxide is not less than 99%. The magnesium aluminum hydrotalcite synthesis method has the beneficial effects that magnesium oxide, magnesium bicarbonate, aluminum hydroxide and sodium hydroxide are used as raw materials, carbon dioxide is not needed to provide a carbonate source, magnesium oxide, magnesium bicarbonate and aluminum hydroxide are all converted into hydrotalcite at proper grinding and temperature, maximized atom economy is realized, meanwhile, few byproducts are produced, the cost is low, the product quality is stable, the magnesium aluminum hydrotalcite has high crystallinity and good particle size uniformity, the purity is high, no impurities are generated, the preparation is simple, the operation is convenient, and ethanol aqueous solution is adopted for grinding and lubrication, so that the particle size unifo