JPH0826719A - Manufacturing method of amorphous aluminosilicate - Google Patents

Abstract

(57) [Summary] [Structure] Amorphous aluminosilicate with excellent thermal stability, characterized in that after the amorphous aluminosilicate is synthesized, it is neutralized until the pH becomes 10.5 or less before drying. Manufacturing method. [Effect] By the production method of the present invention, an amorphous aluminosilicate having a soft particle having a high ion exchange capacity, a high absorptivity of an oily substance and a low cohesive property can be obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to inorganic fillers and additives for rubber, resin, paper, paints, carriers for polymer liquid substances such as oily substances, catalysts and deodorizers. The present invention relates to an amorphous aluminosilicate suitable as a carrier of useful components as a carrier, a remover of free metal ions in an aqueous solution, or a raw material for synthesizing zeolite, and neutralizes until the pH becomes 10.5 or less before drying. The present invention relates to a method for producing an amorphous aluminosilicate having excellent ion exchange performance and excellent oily substance absorption performance.

[0002]

2. Description of the Related Art Conventionally, a typical amorphous aluminosilicate is prepared by mixing, for example, an aqueous solution of sodium aluminate or an aqueous solution of aluminum sulfate with an aqueous solution of sodium silicate at an appropriate temperature, concentration and mixing ratio, and if necessary. It is easily synthesized simply by adding an additional aqueous solution of sodium hydroxide and mixing it.Furthermore, excess mother liquor components such as alkali remaining after being separated from the mother liquor by operations such as filtration are generated from the amorphous aluminosilicate produced. Removed by washing. In many cases, the final product is finally dried by some method. In fact, since the amorphous aluminosilicate produced in this way has a certain degree of oil substance absorption and ion exchange properties, it is used as an industrial raw material for catalysts or catalyst bases, resin additives, ion exchange agents, etc. Was considered useful. However, these amorphous aluminosilicates were obtained as hard particles having a large decrease in ion exchange capacity and agglomeration when dried.

When these amorphous aluminosilicates are used as catalysts, for example, they should be uniformly modified as catalysts (for example, ion exchange with useful metal ions, their salts, etc.). ) Was difficult, and it was difficult to obtain uniform performance as a catalyst. Further, when conventional amorphous aluminosilicate is used as an ion exchanger for removing free metal ions, the internal diffusion rate of ions is slow and the exchange capacity is insufficient, so that the ion exchange performance is not sufficient. Further, even when absorbing an oily substance, its absorption amount, absorption rate, and stability after absorption were insufficient. It is considered that these reasons are due to the difference in surface state, but the detailed mechanism has not been clarified.

Further, in order to remove free metal ions from the aqueous solution, it is desired that the ion exchange rate and the ion exchange capacity are large at the same time. However, it has been known that conventional amorphous aluminosilicates have a gradual decrease in ion exchange capacity when they are dried at a temperature of 50 ° C. or higher and are exposed to the temperature for a long time even at a temperature of 50 ° C. or lower. There is. The cause of such a decrease in the ion exchange capacity has not been clarified, but it has some influence on the site that contributes to ion exchange, that is, the state of Al atoms contained in the skeleton or the surface state that prevents diffusion of ions. The appearance of is believed to be deeply involved.

It has been a very important subject to improve the ion exchange performance of such an amorphous aluminosilicate and the absorbability of an oily substance.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing an amorphous aluminosilicate which has excellent ion exchange performance and oil material absorption performance.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies on the preparation conditions of amorphous aluminosilicates, especially the pretreatment conditions for drying and ion exchange, and the absorption characteristics of oily substances. We have found a close relationship between the amount of residual alkali of aluminosilicate before drying and the ion exchange characteristics, oil substance absorption and cohesion.

That is, it has been revealed that when the drying is carried out in the presence of an alkali, the ion exchange capacity is lowered, or the particles become hard due to the aggregation of the surface. Therefore, the inventors have found that it is possible to improve the ion exchangeability, the absorption of oily substances, and the cohesiveness by reducing the amount of residual alkali before drying, and have reached the present invention.

That is, according to the present invention, an aqueous solution of sodium aluminate or an aqueous solution of aluminum sulfate and an aqueous solution of sodium silicate are mixed at an appropriate temperature, a concentration and a mixing ratio, and if necessary, an additional aqueous solution of sodium hydroxide is added. The amorphous aluminosilicate slurry produced by mixing and mixing is separated into amorphous aluminosilicate and mother liquor by an operation such as filtration, and then the mother liquor components such as excess alkali are removed by washing to remove the alkaline components that cannot be removed. Neutralize with a neutralizing agent such as carbon dioxide or sodium hydrogen carbonate to bring the pH of amorphous aluminosilicate to 10.5.
The present invention provides a method for producing an amorphous aluminosilicate that does not have a surface with strong cohesiveness without causing a decrease in ion exchange capacity due to drying or the like by neutralization until the following. Further, it is not particularly essential to carry out filtration or washing prior to neutralization, and it is also possible to neutralize the mother liquor itself with carbon dioxide gas or the like. Filtering or washing after neutralization can further enhance the effect.

The method for producing the amorphous aluminosilicate of the present invention will be described below.

In the present invention, the synthetic raw material is, for example, an aluminum raw material such as an alkali metal aluminate salt aqueous solution and a silica raw material such as an alkali metal silicate aqueous solution. If necessary, both solutions are diluted with an aqueous solution of alkali metal hydroxide and used.

As the both aqueous solutions, a commercially available aqueous solution of an alkali metal aluminate or an aqueous solution of an alkali metal silicate may be used, or an aluminum source such as aluminum hydroxide or a silica source such as silicic acid may be used as a hydroxide. Both solutions may be prepared by subjecting the solution to heat treatment together with an aqueous solution of an alkali metal salt. The alkali metal salt used is usually
A sodium salt is industrially used, but the sodium salt is not particularly limited. Regarding the concentration of these aluminum raw material and silica raw material solutions, the slurry concentration is preferably 25% by weight or less when the yield of the amorphous aluminosilicate produced by mixing is 100%.

The mixing ratio of both components is Si / Al.
If the ratio is too high, the ion exchange capacity will decrease, and if it is too low, the oil substance absorption capacity will decrease. Therefore, it is preferable to mix the Si / Al ratio in the range of 0.25 or more and 6.00 or less.

The reaction temperature is preferably 50 ° C. or lower. It is also a fact that when the reaction is carried out at a high temperature, a part of the amorphous aluminosilicate is crystallized into sodalite, zeolite, etc., and the oily substance absorbability is remarkably lowered.

The amorphous aluminosilicate slurry obtained by mixing the raw materials is filtered to separate the mother liquor from the amorphous aluminosilicate, and then the alkali component is removed by washing. When pressure, stirring power, etc. are applied to the filter-washed cake thus obtained, the solid cake is re-slurried.

The pH of this slurry exhibits an alkalinity of about 11.0 to 14.0 depending on the difference in the alkali concentration during the synthesis and the degree of washing. Conventionally, such an alkaline substance has been used for drying.

In the present invention, a highly alkaline substance having a pH of 11 or more is neutralized to a pH of 10.5 or less with a neutralizing agent such as carbon dioxide or sodium hydrogen carbonate to sufficiently neutralize the remaining alkaline components. Normal drying is performed.

As the drying method, various methods such as static drying have been proposed in addition to spray drying. Although a decrease in ion exchange capacity can be suppressed by the pretreatment for drying, a drying method in which the amorphous aluminosilicate is not subjected to a high temperature thermal history as much as possible, for example, static drying is preferable.

The present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples.

[0020]

EXAMPLES Each measuring method in Examples and Comparative Examples is as follows.

(1) Method for measuring ion exchange performance The ion exchange capacity was measured by adding 1 liter of an aqueous calcium chloride solution (500 mg / liter in terms of calcium carbonate).
Add 1 g of amorphous aluminosilicate on an anhydrous basis and add
Stir for 10 minutes at 5 ° C. Then, the solid content is separated by filtration, and the calcium remaining in the filtrate is removed by EDTA.
The amount of calcium exchanged per 1 g (anhydrous) of amorphous aluminosilicate measured by titration with an aqueous solution was CaCO ₃
Even if converted to

(2) Method for measuring oily substance absorbency As pretreatment, the powder was pulverized with a cooking cutter until the maximum particle size became 75 μm or less, and the linseed oil method was used in accordance with JIS K6221. The result was determined as the amount of oil absorption per 100 g of amorphous aluminosilicate (anhydride).

Example 1 Water (11322 g) was charged into a reaction vessel having an internal volume of 20 liters, and while maintaining the temperature at 50 ° C., an aqueous solution of sodium aluminate (Na ₂ O = 19.3% by weight, A
l ₂ O ₃ = 21.9% by weight) is also maintained at 50 ° C.
1 g was added and vigorously stirred. Furthermore, an aqueous sodium silicate solution (Na ₂ O = 4.0 wt%, SiO ₂ was added to the same solution).
(12.7 wt%) 3739 g was kept at 50 ° C. and added. The solution in the reaction vessel was continuously vigorously stirred at the time of charging. The time required for charging was about 7.5 minutes. The stirring was continued for 60 minutes from the end of the addition. Immediately thereafter, the obtained slurry was filtered, and the cake was washed on the filter with ion-exchanged water twice the volume of the slurry.
The obtained cake was kneaded into a re-slurry to have a pH of 10.
It was neutralized with carbon dioxide until it reached 0. About 5 of this slurry
After drying at 5 ° C., the ion exchange performance and the absorption of oily substance were measured by the above methods. The results are shown in Table 1.

[0024]

[Table 1]

Example 2 An aqueous sodium aluminate solution having the same composition as in Example 1 was kept at 50 ° C. in a reaction vessel having an internal volume of 20 liters to obtain 92
1 g was added and vigorously stirred. Furthermore, 3739 g of an aqueous sodium silicate solution was kept at 50 ° C. and added to the same solution. The solution in the reaction vessel was continuously vigorously stirred at the time of charging. The time required for charging was 7.5 minutes. The stirring was continued for 60 minutes from the end of the addition. Immediately thereafter, the obtained slurry was filtered, washed and reslurried in the same manner as in Example 1, and neutralized with carbon dioxide until pH 9.0. This slurry was dried at 55 ° C., and the ion exchange performance and the absorption of oily substance were measured by the above methods. The results are shown in Table 1.

Comparative Example 1 A reaction vessel having an internal volume of 20 liters was charged with 921 g of an aqueous solution of sodium aluminate having the same composition as in Example 1 at the same temperature of 50 ° C., and 921 g of the same composition as in Example 1 was added to the solution. A sodium acid aqueous solution, 3739 g, was kept at 50 ° C. and added. The solution in the reaction vessel was continuously vigorously stirred at the time of charging. The time required for charging was 7.5 minutes. The stirring was continued for 60 minutes from the end of the addition. Immediately thereafter, the obtained slurry was filtered, and the cake was washed on the filter with ion-exchanged water in an amount twice the volume of the slurry. The pH of the re-slurried slurry was 12.7. Without neutralization, it was dried as it was at 55 ° C., and the ion exchange performance and oil substance absorption were measured by the above-mentioned methods.
The results are shown in Table 1.

Comparative Example 2 A reaction vessel having an internal volume of 20 liters was charged with 921 g of an aqueous solution of sodium aluminate having the same composition as in Example 1, while maintaining the same temperature at 50 ° C., and the same solution as in Example 1 was vigorously stirred. Aqueous sodium silicate solution of 3739 g
Was maintained at 50 ° C. and charged at a rate of 500 g / min. The time required for charging was 7.5 minutes. From the end of the input,
The stirring was continued for 60 minutes. Immediately thereafter the resulting slurry was filtered. The pH of the re-slurried slurry is 1
It was 3.6. Without neutralization, it was dried as it was at 55 ° C., and the ion exchange performance and oil substance absorption were measured by the above-mentioned methods. The results are shown in Table 1.

[0028]

Industrial Applicability According to the production method of the present invention, amorphous aluminosilicate having a soft particle having a high ion exchange capacity, a high absorptivity of an oily substance and a low cohesive surface is obtained.

Claims (1)

[Claims] 1. A process for producing an amorphous aluminosilicate having excellent thermal stability, which comprises synthesizing an amorphous aluminosilicate and, before drying, neutralizing until the pH becomes 10.5 or less.