JPH07232913A - Production of a type zeolite - Google Patents

Abstract

PURPOSE:To synthesize A type zeolite having a large specific surface area without forming a by-product, especially hydroxysodalite by removing calcium from starting material for synthesizing zeolite before synthesis. CONSTITUTION:When A type zeolite is produced using residue obtd. by incinerating industrial waste as principal starting material, calcium compds. in the powdery starting material are removed and then the starting material is brought into a reaction by heating and stirring in an aq. alkali soln. to produce the objective A type zeolite.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to coal ash, sewage sludge incinerator, papermaking sludge incinerator, which has been regarded as industrial waste in the past.
The present invention relates to a method for efficiently recycling A-type zeolite, which is useful as an adsorbent for gas molecules and low molecular weight organic compounds, by recycling FRP incineration residue, iron-making slag, etc. as a main raw material.

[0002]

2. Description of the Related Art Type A zeolite is produced by hydrothermally crystallizing aluminosilicate gel. The aluminosilicate gel can be obtained by, for example, a method of adding a silica gel aqueous solution to a highly basic sodium aluminate aqueous solution, or a method of adding aluminum hydroxide powder to a highly basic sodium silicate aqueous solution and mixing them. When the silicate gel is heated, the crystal nucleation and crystal growth of the A-type zeolite gradually progress in the gel, and all or most of it is changed to crystalline A-type zeolite.

Thermodynamically, this A-type zeolite is a metastable phase crystal. For example, if the heating temperature is too high, a P-type zeolite that is a stable phase crystal is likely to be produced. If sodium is excessive, hydroxysodalite, which is a stable phase crystal, is likely to be formed. Therefore, if the conditions such as the temperature during hydrothermal crystallization and the composition of raw materials are not limited, A
It is known that type zeolites do not form. P-type zeolite and hydroxysodalite have smaller specific surface area than A-type zeolite, and their performances are greatly inferior such as low catalytic ability, adsorption ability, and ion exchange ability. It is not suitable as an adsorbent.
For this reason, in the production of A-type zeolite, research has been conducted with a focus on how to suppress the change to a stable phase crystal and stop it in a metastable phase crystal state (JP-A-56). -37166 gazette etc.).

However, even in the method using aluminosilicate gel as a raw material, when excessive thermal energy is applied in the crystallization step (when the temperature is too high or the reaction time is too long), the movement of each ion becomes active. Cause rearrangement to a stable phase and hydroxysodalite is generated,
Further, when the gel network structure is too strong and the movement of each ion in the gel is excessively limited, the crystallization reaction itself does not easily occur, and the production rate of metastable phase crystals cannot be increased.

On the other hand, in order to recycle the coal ash which has been conventionally regarded as industrial waste, an attempt has been made to produce zeolite by using the coal ash as a main raw material (Japanese Patent Laid-Open No. 56-14).
9313, JP-A-59-35019, JP-A-61-
178416, JP-A 64-24014, etc.).
In these, a silica source, an aluminum source, and a sodium source are added to coal ash, and the mixture is heated and stirred to synthesize zeolite. In addition to this, zeolite synthesis has been performed using sewage sludge incinerators other than coal ash, papermaking sludge incinerators, etc. as raw materials, but no studies have been conducted to examine the removal of components that inhibit the synthesis of A-type zeolite. It was

[0006]

The present invention solves the above-mentioned problems of the prior art and is a raw material for coal ash, sewage sludge incinerator, papermaking sludge incinerator, FRP incineration residue, ironmaking slag, etc., which have been regarded as industrial waste. It is an object of the present invention to provide a method for effectively removing unnecessary components from the above, and efficiently producing A-type zeolite, which has superior adsorption performance and the like as compared with P-type zeolite and hydroxysodalite.

[0007]

Means for Solving the Problems The production method of the present invention, which has been able to solve the above-mentioned problems, is a method for producing an A-type zeolite from a raw material powder for producing a zeolite. The point is that the reaction is carried out by heating and stirring. Then, as a calcium removing method, a method of washing the raw material with water, a method of treating the raw material with an aqueous acid solution, and a method of stirring while blowing carbon dioxide into water containing the raw material are preferred embodiments of the present invention. Further, the present invention also includes a method for producing a calcium A-type zeolite by performing ion exchange using calcium ions in the drainage discharged when calcium is removed with an aqueous acid solution. The raw material used in these methods is preferably one or more selected from the group consisting of coal ash, sewage sludge incinerator, papermaking sludge incinerator, FRP incineration residue, and ironmaking slag from the viewpoint of recycling. .

[0008]

The present inventors conducted various studies on raw material coal ash and FRP incineration residue in order to increase the yield of A-type zeolite. As a result, it was clarified that the calcium component in the raw material disappeared during the zeolite synthesis reaction process and did not remain in the solution after the reaction. That is, inevitable calcium components such as calcium oxide and calcium sulfate in the raw material react with silica and alumina, which are zeolite synthesis raw materials, and precipitate as calcium silicate or calcium aluminate, which contributes to the actual zeolite synthesis reaction. Since the amount of silica and alumina is decreasing,
After all, it became a condition that hydroxysodalite is easily generated,
The A-type zeolite synthesis rate had decreased.

[0009] Coal ash originally contains the above-mentioned calcium component, but since it is blown during combustion for flue gas desulfurization, the calcium component is inevitably mixed. The FRP incineration residue contains about 20% of CaO dissolved in the glass, and the FRP molded product residue contains nearly 40% of calcium carbonate.
Based on the above findings, the present inventors succeeded in improving the synthesis rate of A-type zeolite by removing these calcium components before the zeolite synthesis reaction, and arrived at the present invention. It was also found that the calcium removal treatment increases the surface area of the raw material. It is considered that the increase of the surface area contributes to the improvement of the synthesis rate of A-type zeolite. Less than,
The present invention will be described in detail.

In the present invention, it is an essential requirement to remove the calcium component from the raw material. Any method can be adopted as a removal method, but as an easy and efficient method, the raw material powder is washed with water, washed with an acid aqueous solution,
Suspended in water, stirred while blowing carbon dioxide, crystallized as calcium carbonate and then selectively separated,
The following three methods can be preferably adopted.

The method of washing with water is a method in which raw material powder is put in water, stirred, and then filtered. This method is simpler and less expensive than the other two methods but needs to be repeated. FIG. 1 shows changes in pH, calcium concentration, and sulfur concentration in the treated water (effluent) when the washing process of putting coal ash in water and stirring it and then performing filtration is repeated. The pH decreased sharply at the beginning and became almost constant. Calcium tends to gradually decrease after the initial sharp decrease, and sulfur tends to decrease gradually. It is considered that this is because among the calcium components in the coal ash, calcium oxide, which is easily soluble in water, is eluted at an early stage, and then calcium sulfate, which is relatively insoluble in water, is gradually eluted.

FIG. 2 shows X-ray diffraction patterns of coal ash before the water washing treatment and after the water washing treatment 10 times. It can be seen that the peaks of calcium oxide and calcium sulfate disappeared by washing with water. In addition, in FIG.
The pH change of the effluent when water washing treatment was performed using different lots of coal ash was shown. The pH decreasing behavior showed the same tendency for the two types of ash, but the starting point and the ending point of pH were different. It is considered that when the type of coal ash and the operating conditions are different, the amount of calcium and the ratio of calcium oxide are different. As a pretreatment of coal ash and other raw materials, it is desirable to remove all the calcium components that elute, but as a guide, the point that the pH becomes almost constant is once agitated for about 10 minutes and repeated 3 to 13 times. For example, most of the soluble calcium component can be removed. The ratio of the raw material powder to water is preferably 30 to 90 g of the raw material powder and 1 liter of water.

The method of washing with an aqueous acid solution is a method of putting raw materials in an aqueous acid solution, stirring and then filtering and washing with water. FIG. 4 shows X-ray diffraction patterns of the coal ash before and after the stirring treatment in a 0.1 N hydrochloric acid aqueous solution. Further, FIG. 5 shows X-ray diffraction patterns before and after acid treatment with 1N hydrochloric acid aqueous solution using FRP incineration residue powder as a raw material. It can be seen that the peaks of calcium oxide, calcium sulfate and calcium carbonate after the treatment disappeared. Examples of the acid used include hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, oxalic acid, acetic acid and the like, and the concentration thereof is 0.0005 to 0.
1N is preferred. The higher the concentration of acid, the faster the elution of calcium components, but the acid may remain in the filtrate and the alkali may be consumed in the subsequent zeolite synthesis reaction.Therefore, wash thoroughly with water after acid treatment. Is preferred.
It is sufficient to repeat the acid treatment itself about 1 to 5 times. The ratio of the raw material to the aqueous acid solution is preferably 1 liter per 30 to 90 g of the raw material.

The carbon dioxide blowing method is a method in which carbon dioxide gas is blown into water containing raw material powder while stirring, and then filtration is performed. Since the water containing the raw material powder can be kept weakly acidic at all times, the elution of calcium is promoted as compared with. FIG. 6 shows the change in pH with time when the coal ash was stirred in water, but what was stirred while blowing carbon dioxide showed that the pH rapidly increased immediately after stirring.
Is falling. FIG. 7 shows X-ray diffraction patterns of the coal ash before and after stirring for 30 minutes while blowing carbon dioxide. It can be seen that the peaks of calcium oxide and calcium sulfate after the treatment disappeared. In this treatment method, it is preferable that the carbon dioxide treatment liquid is blown so that the pH thereof is about 5 to 6, and 1 to 1 liter of water is added to 30 to 90 g of the raw material powder. Also,
The stirring time is 5 to 15 minutes, and it is preferable to carry out 1 to 3 times.

Industrial wastes that can be used as raw materials in the present invention include sewage sludge incinerators other than coal ash, papermaking sludge incinerators, FRP incineration residues, ironmaking slag and the like. Non-powdered ones are preferably used after being pulverized to 50 μm or less because the calcium removal efficiency and the A-type zeolite synthesis efficiency are improved.

After the calcium component removal treatment of the raw material is carried out as described above, an alkali source, a sodium source and water, and if necessary, an aluminum source and a silicon source are added to the raw material, and the temperature is 60 to 90 ° C. Then, the synthesis reaction is performed within 10 hours. A more preferable reaction temperature is 70 to 85 ° C,
A more preferable synthesis time is 1 to 5 hours. Although the reaction is completed in a shorter time as the reaction temperature is higher, the amount of by-products such as P-type zeolite and hydroxysodalite increases. Further, a reaction time that is too long is not preferable because the movement of ions becomes active and rearrangement to a stable phase occurs, the production rate of hydroxysodalite increases, and the yield of A-type zeolite decreases.

The concentration of the alkaline aqueous solution is preferably 2 to 4N. If the alkali concentration is too low, the elution of the reactive component from the raw material will be delayed and the A-type zeolite will not be easily produced. If the alkali concentration is too high, the production rate of hydroxysodalite will increase. If sodium hydroxide is used as the alkali source, it can also serve as the sodium source, but potassium hydroxide, sodium carbonate, sodium hydrogen carbonate or the like can also be used.

Silica and alumina are contained in the raw material, but when the amount of these is small depending on the type of raw material,
It is preferable to add a silicon source or an aluminum source. If the amount of aluminum is too small, P-type zeolite is likely to be formed. As the aluminum source, sodium aluminate is generally used, but aluminum hydroxide, aluminum chloride or the like may be used. As a silicon source,
Sodium silicate, silica sand, silicate glass, etc. are used. In the method of the present invention described above, sodium A type zeolite is mainly synthesized. When the calcium A-type zeolite is obtained by a known ion exchange method, if the acidic drainage discharged when calcium is removed with the above-mentioned aqueous acid solution is used, the calcium ions in the drainage can be effectively used. .

[0019]

The present invention will be described in more detail with reference to the following examples, but the following examples do not limit the present invention.
All modifications and implementations that do not depart from the spirit of the description below are included in the technical scope of the present invention. <Evaluation Method> For the samples obtained in the following Examples and Comparative Examples, crystal identification by powder X-ray diffraction (hereinafter referred to as XRD) method, specific surface area measurement, thermal desorption (hereinafter referred to as TPD)
The amount of adsorbed ammonia was measured by the method, and the crystals were observed by a scanning electron microscope (hereinafter referred to as SEM). The raw material is coal ash, and the XRD measurement results of the synthetic zeolite obtained by the method of the present invention in which zeolite is synthesized after removing calcium by acid treatment and the type A zeolite as a chemical raw material are shown in FIG. The drawing substitute SEM shown
The photographs are shown in FIGS. It was confirmed that the higher the peak intensity of the A-type zeolite in XRD and the more crystals of the A-type zeolite observed by SEM, the higher the specific surface area. Further, the specific surface area and the desorption peak area of TPD (ammonia adsorption amount) have a positive proportional relationship as shown in FIG. 12, and the larger the amount of A-type zeolite produced, the larger the specific surface area and the higher the adsorption capacity. It was confirmed to be excellent.

Example 1 (Removal of calcium by washing with water) Coal ash A to D having different coal types and operating conditions had a solid-liquid ratio of 60 g /
After adding liter of water and stirring for 10 minutes, drainage was removed by filtration. This operation was repeated until the pH became almost constant. The number of repetitions at this time is A (Fig.
(Corresponding to ash 1) was 5 times, and B to D were 10 times. A 3N aqueous solution of sodium hydroxide was added to the obtained coal ash in a solid-liquid ratio of 6
It was added so as to be 0 g / liter and stirred at 85 ° C. for 3 hours. The obtained slurry was filtered, and the XRD and the specific surface area of the obtained zeolite were measured. The results are shown in Table 1. Comparative Example 1 Zeolite synthesis was carried out in the same manner as in Example 1 except that no water washing treatment was performed on the same coal ash A to D as used in Examples. The evaluation results are shown in Table 1.

[0021]

[Table 1]

As is clear from Table 1, in Example, type A zeolite having a larger specific surface area was obtained, and no peak of hydroxysodalite was observed, as compared with Comparative Example in which water washing treatment was not performed. Example 2 (Removal of calcium by washing with water) Using the coal ash A of Example 1, the number of washings with water was 3, 5,
Comparison was performed 9 times. The results are shown in Table 2.

[0023]

[Table 2]

It can be seen that the specific surface area of the A-type zeolite increases a little as the number of washings with water increases. Example 3 (Examination of Zeolite Synthesis Temperature and Time) Coal ash E (corresponding to ash 2 in FIG. 3) was added with water having a solid-liquid ratio of 60 g / liter, stirred for 10 minutes, and then filtered to remove waste water. . After repeating this operation 5 times, a 3N sodium hydroxide aqueous solution was added to the obtained coal ash at a solid-liquid ratio of 60 g.
In addition, the zeolite synthesis was performed under the conditions shown in Table 3. Table 3 shows the XRD and specific surface area measurement results of the obtained zeolite. Comparative Example 2 Water washing treatment was performed in the same manner as in Example 3, and zeolite synthesis was performed under the temperature and time conditions shown in Table 3. Table 3 shows the XRD and specific surface area measurement results of the obtained zeolite.

[0025]

[Table 3]

It can be seen from Table 3 that no A-type zeolite is produced in the comparative example having a short synthesis time even at the same temperature. In addition, in Examples having a high synthesis temperature, generation of hydroxysodalite was recognized as the synthesis time increased. Example 4 (Calcium removal by acid treatment) 0.1N hydrochloric acid was added to the coal ash A to D used in Example 1 so that the solid-liquid ratio was 60 g / liter, and the mixture was stirred for 10 minutes and then filtered. The drainage was removed. This operation was repeated until the pH of the waste water was almost the same as that of hydrochloric acid before treatment.
The number of repetitions at this time was 2 for A and 3 for B to D. After the acid treatment, the slurry was washed with water until the pH became 5 to 7. To the obtained coal ash, a 3N sodium hydroxide aqueous solution was added at a solid-liquid ratio of 60 g / liter, and the temperature was 85 ° C.
And stirred for 3 hours. The obtained slurry was filtered, and the XRD and the specific surface area of the obtained zeolite were measured. The evaluation results are shown in Table 4 together with the results of Comparative Example 1.

[0027]

[Table 4]

Example 5 (Calcium Removal by Acid Treatment) Coal ash A was added with hydrochloric acid having a concentration shown in Table 5 at a solid-liquid ratio of 60 g / liter, stirred for 10 minutes, and then filtered to remove waste water. Removed. This operation was performed twice, and thereafter, zeolite synthesis was performed in the same manner as in Example 4. The evaluation results are shown in Table 5. Example 6 (Removal of calcium by acid treatment) Coal ash A was mixed with 0.2N sulfuric acid at a solid-liquid ratio of 60 g / liter, stirred for 10 minutes, and then filtered to remove wastewater. This operation was performed twice, and thereafter, zeolite synthesis was performed in the same manner as in Example 4. The evaluation results are shown in Table 5.

[0029]

[Table 5]

Example 7 (Removal of Calcium by Acid Treatment) The incineration residue of the FRP molded body was crushed to 40 μm or less, and 50 g of this raw material powder was acid-treated with a 1N hydrochloric acid aqueous solution. Figure 5
In (a), X before acid treatment and in (b) after acid treatment
The line diffraction pattern is shown. It is clear that the calcium carbonate has been removed. Zeolite was synthesized in the same manner as in Example 4 using the raw materials before and after the treatment. The evaluation results are shown in Table 6. Comparative Example 3 is the result of using the raw material before the acid treatment.

[0031]

[Table 6]

Example 8 (Removal of Calcium by Blowing Carbon Dioxide) Water having a solid-liquid ratio of 60 g / liter was added to coal ash A, and the mixture was stirred for 10 minutes while blowing carbon dioxide gas at 1.5 liter / minute, and then filtered. I went and removed the drainage. Zeolite synthesis was performed and evaluated in the same manner as in Example 1 for the case where this operation was performed once and the case where it was performed three times. The evaluation results are shown in Table 7 together with the results of Comparative Example 1.

[0033]

[Table 7]

Example 9 (Production of Ca ion-substituted zeolite) The Na zeolite powder obtained in Example 5 (Sample 1)
And 2) in the acidic waste liquid (Ca concentration: 1 mol / liter) discharged in Example 5 in which Ca is equal to or more than the Na exchange amount of zeolite.
The weight of the zeolite powder and the amount of the discharged liquid were adjusted so that the concentration existed, and the suspension was suspended and kept at 30 ° C. for 30 minutes. This was repeated 3 times, washed with water and dried, and then the specific surface area was measured. As a result, the specific surface area of Sample 1 was 356 m ² /
After substitution of Ca to 402 m ² / g, C in sample 2
It was increased by about 10% from 376 m ² / g before substitution with a to 418 m ² / g after substitution with Ca. Also, sample 1
From the X-ray diffraction chart (Fig. 13), it was found that there was no change in the pattern of A-type zeolite before and after the substitution, and calcium A-type zeolite was obtained.

[0035]

EFFECTS OF THE INVENTION The present invention is constituted as described above, and by performing a calcium removal treatment from a raw material powder before synthesizing a zeolite, an A-type zeolite having a large specific surface area can be obtained as a by-product (particularly hydroxysoda). It was possible to provide a manufacturing method capable of synthesizing without producing light). According to the present invention, A-type zeolite can be synthesized from not only coal ash but also industrial waste such as FRP incineration residue or sewage sludge incinerator, papermaking sludge incinerator, and ironmaking slag, which is useful from the viewpoint of recycling. It is an invention.

[Brief description of drawings]

FIG. 1 is a diagram showing changes in pH, calcium concentration, and sulfur concentration in drainage depending on the number of washing treatments.

FIG. 2 is a diagram showing X-ray diffraction results of coal ash before and after washing with water.

FIG. 3 is a diagram showing a change in pH of waste liquid when water washing treatment is performed using ash of different lots.

FIG. 4 is a diagram showing X-ray diffraction results of coal ash before and after acid treatment.

FIG. 5 shows X-ray diffraction results of FRP incineration residue before and after acid treatment.

Fig. 6 pH of water containing coal ash by blowing carbon dioxide
It is a figure which shows the time-dependent change of.

FIG. 7 is a diagram showing X-ray diffraction results of coal ash before and after carbon dioxide blowing treatment.

FIG. 8 is a diagram showing X-ray diffraction results of A-type zeolite obtained by removing calcium by pickling treatment and then synthesizing it, and A-type zeolite as a reagent raw material.

FIG. 9 is a drawing-substitute scanning electron micrograph showing the crystal structure of coal ash.

FIG. 10 is a drawing-substitute scanning electron microscope photograph showing the crystal structure of A-type zeolite obtained by synthesizing calcium after removing calcium by pickling treatment.

FIG. 11 is a drawing-substitute scanning electron micrograph showing a crystal structure of A-type zeolite as a chemical raw material.

FIG. 12 is a diagram showing the relationship between the specific surface area of A-type zeolite obtained by the method of the present invention and the results of measuring the amount of adsorbed ammonia by the temperature programmed desorption method.

13 is a diagram showing X-ray diffraction results before and after ion exchange in Example 8. FIG.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shunichi Toyama 1-3-18 Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo Kobe Steel Works, Kobe Head Office (72) Inventor Masaru Horii Wakihama, Chuo-ku, Kobe-shi, Hyogo Prefecture 1-38, Machi Kobe Steel Works, Ltd. Kobe Head Office

Claims (6)

[Claims] 1. When producing an A-type zeolite from a raw material powder for producing a zeolite, the calcium compound in the raw material powder is removed, and then the mixture is heated and stirred in an alkaline aqueous solution to react with the A-type zeolite. Production method. 2. The method for producing an A-type zeolite according to claim 1, wherein the calcium compound in the raw material is removed by washing the raw material powder with water. 3. The method for producing an A-type zeolite according to claim 1, wherein the calcium compound in the raw material is removed by treating the raw material powder with an aqueous acid solution. 4. The method for producing an A-type zeolite according to claim 1, wherein the calcium compound in the raw material is removed by stirring while blowing carbon dioxide into water containing the raw material powder. 5. The raw material powder according to any one of claims 1 to 4 is at least one raw material powder selected from the group consisting of coal ash, sewage sludge incinerator, papermaking sludge incinerator, FRP incineration residue, and ironmaking slag. Method for producing A-type zeolite. 6. The method for producing an A-type zeolite according to claim 3, wherein the calcium A-type zeolite is produced by ion exchange utilizing the calcium ions in the acidic effluent discharged by removing the calcium compound.