KR870000365B1 - Production of hydrotalcite with amended characteristics - Google Patents

Abstract

Hydrotalcite was prepd. by treating MgO or Mg(OH)2 with AlCl3 or Al2SO3 under Na2CO3 soln. Thus, 45.1 g anhyd. Na2CO3 and 13.6g MgO were mixed in 250ml H2O and stirred for 10min. After the resulting slurry was boiled at 85 C, 33.3g Al2CO3 in 250ml H2O was treated to give 30-33g hydrotalcite.

Description

Process for producing hydrotalcite

The present invention relates to a method for preparing hydrotalcite in crystalline form with excellent filterability.

Hydrotalcites are known minerals that are found, for example, in Norway, the Soviet Union and Austria. In addition, hydrotalcite can be synthesize | combined by the following well-known method. In other words, ammonium carbonate or dry ice is added to a mixture of magnesium oxide and r-alumina (or pyrolysis products of magnesium nitrate and aluminum citrate), and then heated to a temperature of up to 325 ° C. at a high pressure of 2,000 to 20,000 psi, thereby removing the hydrotal There is a method of synthesizing a site [Roy et al. Am. J. Science 251,350 (1953).

Hydrotalcite can also be synthesized by reacting aqueous aluminum salts and aqueous magnesium salts with sodium carbonate and sodium hydroxide [DE 1592126 (1967)].

Hydrotalcite is also produced during the aging of a mixture of aluminum hydroxycarbonate gel and magnesium hydroxide gel at 25 ° C. for at least 500 days [Vanderlaan et al, J. Pharm. Science 71,780 (1982).

However, the aforementioned methods have several drawbacks. The first cited method is impractical for industrial scale production because it must be carried out under hot mill pressure. In addition, the second cited method has the drawback that a product in a gel state is obtained which is very easily absorbed and very difficult to filter. In addition, cleaning this product makes a person tired and has the drawback of requiring special isolation and drying processes.

The third cited method is also inadequate for industrial production because of the obvious drawbacks that require a great deal of time.

The present invention relates to a method for producing hydrotalcite of Al ₂ O ₃ · 6MgO · CO ₂ · 12H ₂ O, characterized by reacting magnesium oxide or magnesium hydroxide with a solution of aluminum chloride or aluminum sulfate in the presence of an aqueous sodium carbonate solution. It is about.

~100℃, 바람직하게는 80

~90℃의 온도에서 진행시키는 것이 바람직하다.This reaction is high temperature, especially 70

˜100 ° C., preferably 80

It is preferable to advance at the temperature of -90 degreeC.

According to the present invention, when the reaction proceeds at a high temperature, preferably at a temperature of about 85 ° C., a aging time of up to 50 days is allowed to react for several hours by reacting a mixture of aluminum hydroxycarbonate gel and magnesium oxide or magnesium hydroxide. It can be shortened. X-ray diffraction analysis can be used to determine the loss of magnesium hydroxide or magnesium hydroxide and the oxides and the formation of hydrotalcites. Hydrotalcite contains magnesium oxide even after reaction at 85 ° C. for 2 hours, but after 4 hours, magnesium oxide disappears completely, and the reaction product is pure hydrotalcite. The hydrotalcite thus obtained is easily filtered and can be easily washed with water. It is difficult to isolate, wash and dry, and no gelled product (and a gelled product obtained by reacting the water-soluble aluminum salt and water-soluble magnesium salt with sodium carbonate and sodium hydroxide according to the above-mentioned prior art German Federal Patent) are not produced.

The aluminum hydroxycarbonate gel can be prepared by adding a solution of aluminum chloride or aluminum sulfate to a solution of sodium carbonate / sodium bicarbonate, as described [Vanderlaan et al., Loc. cit. and Hemet al., J. Pharm. Sci 59, 317 (1970). For the practical method, it is much simpler to prepare the gel by adding an aluminum sulfate or aluminum chloride solution to a slurry of sodium carbonate / magnesium oxide. The molar ratio of aluminum to magnesium should be 1: 3. The temperature should be maintained at about 85 ° C. 4 hours is sufficient to complete the reaction.

The nature of the resulting hydrotalcite depends on the concentration of reactant used. Hydrotalcite with the best acid binding activity and antacids was found in the following concentrations: aluminum salt-0.2 mol / 1000 ml. Obtained when used in concentrations of magnesium oxide-0.6 mol / 1000 ml and sodium carbonate-0.85 mol / 1000 ml (ie Al salt: MgO: Na ₂ CO ₃ = 0.1: 0.3: 0.425).

The acid binding activity of the prepared hydrotalcite can be measured by measuring the number of ml of 0.1 N hydrochloric acid required to neutralize 1 g of the product.

Antacids guide the delayed activity. This is measured by adding 1 g of the prepared material to 150 ml of 0.1 N hydrochloric acid at 37 ° C. and stirring the suspension for 80 minutes. The pH value is measured every 10 minutes, and 20.0 ml of 0.1N hydrochloric acid is added.

Samples prepared according to the present invention exhibit an acid binding activity of at least 270 ml of at least 0.1 N hydrochloric acid and a pH value of 3.0 or less in the antacid test after 70 minutes.

Examples of the present invention are as follows.

Example 1

To 250 ml of distilled water was added 45.1 g of anhydrous sodium carbonate and 13.6 g of 90% magnesium oxide (hard). After stirring for 10 minutes, the slurry was heated to 85 ° C. 33.3 g of aluminum sulfate 18 hydrate dissolved in 250 ml of distilled water was added dropwise over 1 hour. Heated more than 4 hours. The slurry was allowed to cool to room temperature. The white precipitate was filtered (Buchner funnel) and washed with 100 ml of distilled water. The product was taken out of the Buchner funnel and added to 200 ml of distilled water. After stirring for 30 minutes, it was again filtered off, washed with additional water to remove sulfate ions, sucked to dry completely and dried at 70 ° C. for 15 hours. Yield: 30-33 g, acid binding activity: 290 ml N / 10 HCl.

Example 2

13.6 g of hard magnesium oxide (90%) was added to a solution of 45.1 g of anhydrous sodium carbonate. The slurry was stirred for 30 minutes and then heated to 85 ° C. 24.1 g of aluminum chloride hexahydrate was added dropwise to 250 ml of distilled water over 1 hour. After at least 4 hours at 85 ° C., the reaction mixture was cooled to room temperature and then isolated by filtration in a Buchner funnel. As in Example 1, washing and drying were performed. Yield: 31.0 g, acid binding activity: 298 ml N / 10 HCl.

Example 3

An aqueous solution of 0.05 mol (24.1 g) of aluminum chloride hexahydrate in 100 ml of distilled water was added to an aqueous solution of 0.425 mol (45.1 g) of anhydrous sodium carbonate in 150 ml of distilled water to prepare an aluminum hydroxycarbonate gel. After stirring for 30 minutes at room temperature, the slurry was added to a preheated (85 ° C.) slurry of 0.3 mol (12.2 g) of magnesium oxide in 250 ml of distilled water over 1 hour. The temperature during the addition was maintained at 85 ° C. The reaction mixture was further heated at 85 ° C. for 4 hours and then cooled to room temperature and treated as in Example 1. Yield: 30.5 g, acid binding activity: 286 ml N / 10 HCl.

Claims (7)

The method of filtration is the preferred formula _{Al 2 O 3 · 6MgO · CO} 2 · 12H ₂ O sites in the hydrotalcite crystals of sodium carbonate in the presence of magnesium hydroxide or magnesium oxide solution characterized by the Sikkim aluminum chloride or aluminum sulfate and reaction. The method of claim 1 wherein the reaction is carried out at high temperature. The process according to claim 1 or 2, wherein the reaction is carried out in a temperature range of 70 ° C to 100 ° C. The process of claim 1 or 2, wherein the reaction is carried out at about 85 ° C. The method according to claim 1 or 2, wherein the molar ratio of the reactants is aluminum salt: magnesium oxide (or magnesium hydroxide): sodium bicarbonate = 0.1: 0.3: 0.425. 4. A process according to claim 3, wherein the molar ratio of the reactants is characterized in that aluminum salt: magnesium oxide (or magnesium hydroxide): sodium bicarbonate = 0.1: 0.3: 0.425. The method according to claim 4, wherein the molar ratio of the reactants is aluminum salt: magnesium oxide (or magnesium hydroxide): sodium bicarbonate = 0.1: 0.3: 0.425.