JPH01138115A - Method for producing faujasite type zeolite - Google Patents

Abstract

PURPOSE:To obtain a zeolite having high base-substitution capacity, adsorption power and moisture-uptake, in high efficiency, by using burnt coal ash as a main raw material and forming the zeolite crystal while keeping the SiO2/Al2O3 ratio within a specific range by supplying SiO2 or an Al component to the main raw material. CONSTITUTION:Burnt coal ash is used as a main raw material and is supplied with deficient SiO2 component or Al component to keep the SiO2/Al ratio to 1-7. The mixed raw material is heated in an alkaline solution to form crystals. A faujasite-type zeolite having high base-substitution capacity, adsorption power and moisture-uptake can be produced by this process. The zeolite is useful as a solid improver, an anti-caking agent for fertilizer, a deodorizer, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention relates to a method for producing faujasite-type zeolite using coal combustion ash as a main raw material.

b. Prior art and problems to be solved The amount of coal combustion ash discharged and disposed of from thermal power plants in Japan reaches 2 million tons every year, and is expected to increase in the future. Currently, there is little treatment available for most of these, other than disposing of them in landfills as solid waste. In order to solve these problems, there is a strong need for the development of technology for recycling coal ash.

Coal ash is mostly inorganic components contained in coal that remain as oxides after combustion. Therefore, although there are some differences in chemical composition depending on the type of coal, the main components are silicic acid (SiO□) and aluminum oxide (A 1 zoz).
It also contains small amounts of oxides such as ferric oxide (FezOx), mag7sium, and calcium.

These components reach a high temperature of about 1,300° C. when coal is burned, and their concentration decreases when they reach the exhaust flue, so they exist in the form of glass. Natural volcanic glass is known as something similar to these, but it is also known that by treating it with an alkali, it can be transformed into sodalite.

Means for solving the C0 problem The present invention uses coal combustion ash alone or mainly contains coal combustion ash, and depending on the content of silicic acid or aluminum contained in the coal combustion ash, the silicic acid component or the aluminum component is added to the coal combustion ash. silicic acid (Stow)/aluminum (
^β20. ) ratio within a specific range, crystal formation is performed by heat treatment in an alkaline solution, and coal combustion ash is converted or synthesized (hereinafter referred to as synthesis) to efficiently obtain faujasite type zeolite.

The coal combustion ash used as the main raw material in the present invention is peat.

Combustion ash of lignite, brown coal, bituminous coal, anthracite, etc. can be used. When these combustion ashes are to be efficiently synthesized into faujasite-type zeolite, the finer the particles of coal combustion ash, the shorter the crystal formation time, and at the same time the yield is improved. However, the particle size of fly ash,
That is, it is possible to easily synthesize faujasite type zeolite by using a zeolite having a particle size of 45 μm or less and heating it in an alkaline solution.

The molecular formula of the faujasite type zeolite obtained by the present invention is, for example, NazO・A 1.03・3.3S
iO□・7H,O.

When synthesizing faujasite-type zeolite from coal combustion ash, the synthesis reaction is affected by the content of silicic acid and aluminum in the coal combustion ash, so these components must be analyzed in advance to accurately understand the content. Must be.

When crystallizing in an alkaline solution to obtain faujasite-type zeolite, it is necessary to keep the silicic acid (SiOz)/aluminum (A 1 z(h) ratio within a certain range.When the silicic acid content is low The production rate of faujasite type zeolite can be increased by supplementing the silicic acid component and, if the aluminum content is low, the aluminum component.

The Sing/AlzOs ratio is suitably about 1.0 to 7.0, preferably about 2.0 to 4.0.

As a source of silicic acid for replenishment, sodium silicate (NazSi
zO*) is suitable, but silicic acid (SIO2n)lxo)
or silicon dioxide (Sin), etc. can be used.

In addition, sodium aluminate (
NaA 10. )・Aluminum powder, aluminum hydroxide (A j! (OH) x), aluminum chloride (AfC7! x) are suitable.

Aluminum oxalate (9A 1 , Q, ・2B!03>
Aluminum compounds such as; aluminum minerals such as corundum, diasbore, boehmite, gypsumite, and alumite can also be used.

Next, a method for synthesizing coal combustion ash into faujasite-type zeolite will be outlined.

A certain amount of coal combustion ash is placed in a reaction vessel, and a 0.1 to 8N solution of sodium hydroxide solution, preferably 1 to 4N, is added to it.
Add 4 to 15 times the volume of the specified liquid to the coal combustion ash. A reflux condenser is attached to this, and the mixture is heated at 70 to 450°C, preferably 75 to 130°C, at normal pressure to carry out a crystal formation reaction.

At this time, a stirrer may be attached to stir the mixture, but only at the initial stage when crystal formation begins. Care must be taken because stirring at a later stage of crystal formation may actually suppress crystal formation. The time for crystal formation is achieved between 1 and 36 hours. After cooling, unreacted sodium hydroxide is separated, washed with water, and dried to synthesize faujasite type zeolite.

In this case, unreacted sodium hydroxide is recovered, consumed alkali is replenished, and used for the next reaction.

The faujasite type zeolite obtained in this way has high base substitution capacity, adsorption power, and moisture absorption power, so it is useful as a soil conditioner, fertilizer anti-caking agent, and feed additive.

Builder for deodorizers, water purifiers, moisture absorbers, and detergents.

It has a wide range of applications, including industrial catalysts, and has many uses.

Faujasite-type zeolite (
NatO+ A I-zoz ・3.3SiOz ・
7HzO) Typical methods for converting and synthesizing H are described in detail below using Examples.

The coal combustion ash used in this example was a small amount of coal combustion ash and its fly ash, and the analytical values for the fly ash used are shown in the table below.

Chemical analysis value (%) of coal combustion ash Example 1 300 g of fly ash with a particle size of 45 μm or less
Transfer to a flask of m1 (SiOg/Al1zOa=4.
88) - Add 150ml of 3N sodium hydroxide solution to this.
1 and stir well. Next, a reflux condenser was attached and the mixture was heated at 85° C. for 10 hours to generate crystals. After crystal formation, it was filtered, washed with water and dried to synthesize faujasite type zeolite. The base displacement capacity (CEC) of the product obtained by this production method is 190 meq / 10
0g, and the faujasite type zeolite content is approximately 40
%Met.

Example 2 20 grams of fly ash with a particle size of 45μ or less and 4 grams of sodium aluminate are placed in a 300+14 flask (SiJ/A A' zJ = 3.08).
. Add 150n of 3N sodium hydroxide to this, stir well, and then attach a reflux condenser to it.
The mixture was heated at 85° C. for 10 hours to generate crystals. This was heated for 3 pa, washed with water, and then dried to synthesize faujasite type zeolite. The base displacement capacity ffi (CEC) of the product obtained by this production method was 305 neq/100 g. In addition, the content of faujasite type zeolite is approximately 5
It was 5%.

Example 3 Fly ash with a particle size of 45 μm or less has a capacity of 5 times that of a mouse.
．． 5N hydrochloric acid was added (in this case, mineral acids such as sulfuric acid and nitric acid may also be used), and the mixture was heated at 80° C. for 30 minutes to elute small amounts of iron oxide and other bases, which were then washed with water. Transfer an amount equivalent to 20 grams of this anhydrous to a 3001111 flask,
4.5 grams of sodium aluminate and 3N sodium hydroxide 150(1) A were added and stirred well (S
iO□/^i, o3=2.92). This was equipped with a reflux condenser and heated at 85° C. for 0 hours to form crystals. This was filtered, washed with water, and dried to synthesize faujasite type zeolite. The base displacement capacity (CEC) of this product was 400 meq/100 g.

Further, the content of faujasite type zeolite was about 90%.

Note 1) Base substitution capacity i (CEC) is Scholl
Defined by Emberger's method.

Note 2) The faujasite-type zeolite content was measured using an X-ray diffractometer (manufactured by Rigaku Denki), using α-alumina as an internal standard substance, and measuring 2θ-20.2° (d = 4.3).
9 people) as the representative diffraction peak, measured the peak area,
It was determined from a calibration curve prepared in advance using Molecular Sieves 13X as a standard.

When the products obtained by the methods of Examples 1 to 3 were diffracted using an X-ray diffractometer (manufactured by Rigaku Denki Co., Ltd.), all the samples showed 14.3.8.75.7.51°5.71
．． 4.7B, 4.39.3.93.3.79.3.7
4.3.32゜3.03.2.93.2.87.2.7
A peak appeared at 6, 2.65.2.60.2.39°219, and its intensity was strongest in the sample obtained by the method of Example 3, followed by the product of Example 2 and Example 1. The order was The position of this peak also clearly proves that it was synthesized into faujasite type zeolite. However, these peaks are not observed at all in the fly ash used as the raw material.

Claims (2)

[Claims] (1) A method for producing faujasite-type zeolite, which is characterized by using coal combustion ash as the main raw material. (2) Supplementing silicic acid or aluminum components to coal combustion ash, silicic acid (SiO_2)/aluminum (Al_2O_
3) A method for producing faujasite-type zeolite, which comprises heating and crystallizing in an alkaline solution while maintaining the ratio between 1.0 and 7.0.