JPH0567567B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a novel method for synthesizing zeolite in an aqueous solution.

[Prior art and problems to be solved by the invention] In general, zeolite, which is an aluminosilicate,
It has various useful properties such as ion exchange, molecular sieving, adsorption, and catalysis, and is therefore widely used in industry today. In order to improve the properties of such zeolite, it is important to make the particles finer and the particle size more uniform, and therefore various attempts have been made to date.

By the way, most of the methods for artificially synthesizing zeolite involve synthesizing it in an aqueous solution. This synthesis of zeolite in an aqueous solution has a simple reaction mechanism and does not require special equipment, so it is widely recognized as a method for synthesizing artificial zeolite in large quantities and at low cost. However, when synthetic zeolite is synthesized in an aqueous solvent, the viscosity of the solution is low, and the crystal growth rate is fast after the crystal nuclei are formed.As a result, it is difficult to control the reaction, and the resulting zeolite particles are difficult to control. Synthesizing homogeneous and fine zeolite in an aqueous solution has been extremely difficult, as the particle sizes cannot be allowed to be uneven and large particle sizes are produced.

[Means for Solving the Problems] In view of the above-mentioned circumstances, the present invention was created with the aim of providing a new method for synthesizing zeolite that can eliminate these drawbacks. In the synthesis, the solvent is an aqueous solvent containing a water-soluble polymer.

Examples of the aqueous polymer used in the present invention include natural water-soluble polymers (including those made water-soluble through modification) such as gelatin, β-cellulose, alginic acid, and carboxymethylcellulose, or polyvinyl alcohol and polyacrylamide. Water-soluble polymers synthesized in can be used alone or in combination.

The reason why the present invention is effective in synthesizing uniform and fine zeolite is that the crystal formation site for zeolite synthesis is different from the conventional aqueous solution.
By making an aqueous solution of a water-soluble polymer, the polymer becomes a viscous solvent, and the reaction reagent acts as a solvent in the aqueous solution and is surrounded by the dissolved water-soluble polymer. The rapid growth of crystals is suppressed and moderate crystal growth occurs, resulting in the formation of a large number of crystal nuclei, and the growth of the harmfully formed crystal nuclei is suppressed and delayed, resulting in uniform grain size. Furthermore, it is thought that fine artificial zeolite was produced.

The present invention relates to zeolites of various compositions synthesized in an aqueous solution system, such as zeolite A, zeolite X, zeolite Y, zeolite Z, and zeolite
It can be carried out in the synthesis of GMS-5, mordenite, and the like.

[Effect] When fine zeolite particles are synthesized in an aqueous solution system, since the solvent is an aqueous solution of a water-soluble polymer, crystal growth is moderate, resulting in uniform particle system and fine artificial zeolite particles. As a result, fine, uniformly sized, high-performance zeolite particles, which were thought to be impossible in conventional aqueous solutions, can be easily produced by simply replacing the reaction solvent with an aqueous solution and using a water-soluble polymer aqueous solution. It is possible.

Next, examples of the present invention will be described.

[Experiment 1] In a three-necked flask containing 40 c.c. of water, mix 4 grams (g) of sodium hydroxide, 2 g of sodium aluminate, and 14 grams (g) of colloidal silica in a 40 wt% aqueous solution, and then Gelatin, which is a water-soluble polymer, is 0.0wt% (weight percent), 0.1wt%
%, 0.5wt%, 1.0wt%, 3.0wt%, 5.0wt%,
Aqueous solutions of 7.5 wt% and 10 wt% were respectively added and stirred, aged for 1 hour at room temperature, and reacted for 10 hours while heated to 100°C.

The reaction product was filtered, and the filtered product was washed with water and dried to obtain white crystals. As a result of identifying this substance using powder X-ray diffraction method, it was identified as faujasite,
Furthermore, after measuring its lattice constant, it was confirmed that it was zeolite Y.

The yield of this reaction product is shown in the table shown in Figure 1, which shows that the amount of gelatin added is
A particularly rapid decrease was observed when exceeding 5.0wt%,
It is recognized that gelatin is working effectively to suppress the production rate of zeolite Y.

[Experiment 2] Of the zeolite Y produced, the amount of gelatin added was 0.0wt%, 0.1wt%, 1.0wt%, and 7.5wt%.
The particle size distribution of each sample was measured, and the results are shown in the table of FIG. However, when the amount of gelatin added was 7.5 wt%, zeolite Y was used, which was reacted for 20 hours and had a yield of 98%.

According to this, in the product without gelatin (comparative example), the particle size is distributed over a wide range from 0.66 μm (micrometer) to 42.21 μm, and the cumulative particle size of 50% is 4.71 μm. μ
It is confirmed that the width of the particle size distribution becomes smaller in all the products to which gelatin is added, and the cumulative particle size of 50% also decreases.
It was observed that the defects were reduced to 3.55 μm for the gelatin concentration of 0.1%, 1.97 μm for the 1.0% gelatin concentration, and 1.70 μm for the 7.5% gelatin concentration. It is confirmed that the particle sizes are clearly more uniform compared to those without the addition. Moreover, the width of the particle size distribution becomes narrower as the amount of gelatin added increases, indicating that crystals with a more uniform size can be obtained. As a result of electron microscopic observation of the obtained crystals, it was also observed that the higher the gelatin concentration, the more rounded the octahedral structure was.

Furthermore, it can be confirmed that the average particle size of zeolite Y becomes smaller as the amount of gelatin added increases.

[Experiment 3] The reaction conditions were the same as in Experiment 1, and the amounts of sodium aluminate and 40 wt% aqueous colloidal silica were varied, and the amounts of gelatin added were 0.0 wt%, 1.0 wt%, and 10.0 wt%. %, the region where zeolite Y is produced in a single phase was investigated. The results are illustrated as a reaction composition diagram in FIG.

According to this, zeolite Y that does not contain gelatin cannot be obtained as a single product in a region where the proportion of silicon oxide is less than 2.5 mol percent (mol%), but a mixture with Herschelite is obtained. Yes, gelatin 1.0wt
% added, the percentage of silicon oxide is approximately
It was possible to obtain zeolite Y as a single product to the extent that the amount decreased to 1.0 mol%. A decrease in the proportion of silicon oxide means an increase in the proportion of aluminum oxide in zeolite Y, which also means that the ion exchange ability is excellent and the catalytic activity is increased.

In addition, in the case where gelatin was added up to 10.0 wt%, zeolite Y was produced in a region where the proportion of silicon oxide further decreased.

From this result, when gelatin is added,
It was observed that the production region of zeolite Y was expanded compared to the case where no addition was made, and zeolite Y having a composition with a high aluminum content could be easily obtained.

Example 4 0.5 g (g) of sodium hydroxide and sodium aluminate were added to a three-necked flask containing 28 c.c. of water.
1.5g, 30g (g) of 40wt% aqueous solution of colloidal silica was mixed, and further 0.0wt%, 0.1wt% ( After adding and stirring, the mixture was aged at room temperature for 15 hours, and then reacted at 100° C. for 5 hours.

The reaction product was filtered, and the filtered product was washed with water and dried to obtain a white powder of zeolite A.

The particle size distribution of this material was measured and the results are shown in the table of FIG. It is also observed that the particle size distribution range of the sample to which polyvinyl alcohol was added was narrower and the particle size was smaller than that of the comparative example that did not contain polyvinyl alcohol.

In this case as well, it was confirmed through a separate experiment that the zeolite production region was expanded, just as in the case of the gelatin-added product.

[Brief explanation of the drawing]

In the drawings, Fig. 1 is a graph showing the yield of the reaction product when gelatin is added, Fig. 2 is a table showing the particle size distribution state of the same product, and Fig. 3 is a graph showing the yield of the reaction product when gelatin is added.
The figure is a table showing the reaction composition diagram of the same product.
The figure is a table showing the particle size distribution of the product when polyvinyl alcohol is added.

Claims (1)

[Claims] 1. A novel method for synthesizing zeolite, characterized in that when zeolite is synthesized in an aqueous solution, the solvent is an aqueous solution solvent containing a water-soluble polymer.