JPS5852925B2 - Natural zeolite modification treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for modifying natural zeolite, more specifically, a method for modifying natural zeolite containing clinoptilolite and mordenite as main components by pressurized hot water treatment in an alkaline aqueous solution. Regarding.

Natural zeolite is produced in various parts of Japan and is widely used, especially in agricultural applications.

The basic structure of zeolite is composed of Si (silicon) and four O (oxygen) to form a condensed acid structure of silicate.
It has a structure in which a 5in4 tetrahedron with a 5 in 4 tetrahedron placed at the apex and an A704 tetrahedron in which Si is replaced with AA (aluminum) are connected to each other in various ways.

In this way, zeolite has a three-dimensional structure of aluminosilicate and contains water molecules and exchangeable cations in the large cavities of condensed anions, and its chemical composition also depends on the Si/AA ratio of the zeolite skeleton and the exchangeable cations. type and amount;
They are diverse due to differences in the number of water molecules within the unit cell, etc.
As a result, natural zeolites include the sodazoite group and the turbidite group.
There are many types, such as the gismonden group, the diazoite group, the philipsite group, the chabazite group, and the quasi-zezoite group, each with its own characteristics.

Among these, in view of the domestic production situation, the zeolites that can actually be used are clinoptilol zeolite of the diabolite-studiosite group and mordenite of the diazoite-gismonden group.

These zeolites occur as white or green tuff,
In addition to zeolite, its components include impurities such as quartz, cristobalite, and volcanic glass.

Unlike synthetic zeolites, the problem with natural zeolites in applications is that they contain many of the impurities mentioned above.

For this reason, the uses of natural zeolite are limited, such as in fields with low added value, such as agricultural fertilizer stabilizers, soil conditioners, wastewater purification, and odor removal sprays, or adsorption, such as air separation. At present, it is used in fields that do not require advanced technology, such as dehumidifying benzene and gasoline, and is not used as an industrial adsorbent like synthetic zeolite.

Conventionally, natural zeolites have not been used much as adsorbents as mentioned above, and most of them have been used for agricultural purposes and as fillers.

This is because natural zeolite has a higher content of impurities than synthetic zeolite, so its properties are poor, such as poor adsorption ability.
This is due to extremely poor ion exchange ability and other aspects.

Chemical treatments for modifying natural zeolite include high-temperature methods and low-temperature methods, and there are few examples of low-temperature methods.

The most common example is the high-temperature method, in which natural zeolite and similar minerals are used as raw materials, chemicals are added to them, and calcination is performed at 800°C to 1000°C. Many efforts are being made to produce synthetic zeolites.

Two of the few examples of low-temperature methods are as follows.

One example is a natural clinoptilol group stone with 10~
Grind into 20 mesh pieces and air dry.

This was prepared in an Erlenmeyer flask at 1, 3, 5, and 10 normal concentrations N.
of sodium hydroxide (NaOH) at a ratio of 107 rLl per 3 grams (gr) of zeolite, stoppered, and
Continuous heat treatment for maximum ioo hours (HR) in a 5°C water bath.

The treated sample is repeatedly decanted and washed with water until the hydrogen ion concentration (PH) of the supernatant reaches 8 to 10, and then dried at a temperature below the treatment temperature.

What is obtained is a P-type zeolite analog when treated with 1, 3, 5 (N) sodium hydroxide, and a sodalite when treated with 1ON sodium hydroxide.

The time required for the crystals of this P-type zeolite analog to begin to grow is 70 HR or more in the 1(N) treatment, and 5 to 10 HR in the 1(N) treatment.
It is reported that the time required for the reaction to complete in the (N) treatment is 50 to 70 HR or S, especially in the 5(N) treatment.

In another example, a solution of 3 (N) sodium hydroxide to 20 (gr.
, 6 , 8 (HR) treatment, and then decantation until the pH of the supernatant becomes 10 or less.

As mentioned above, in the former example, a long patent application period was spent on chemical treatment until the reaction was completed, and the amount of alkali used was 13% to 133% per unit raw material, and among these, the higher the alkali concentration, the faster the reaction rate. The properties of the zeolite obtained quickly are also said to be good.

In fact, unless treated with 5N alkaline solution for 70HR or more, the cation exchange capacity (CEC) will be 300 (meq/100.
? r), and for this reason, high alkalinity conditions cannot be avoided in water droplets for a long time.

The same thing can be said for the latter example; the amount of alkali used is as high as 50% per unit of zeolite, and no significant improvement in adsorption performance can be seen unless the treatment time is 6 HR or more, especially in the case of adsorption performance at low concentrations. It is not much different from the processing one.

In these cases, considering the high cost due to high alkali, the processing of a large amount of washing water and its waste water during post-processing washing, and the increase in processing equipment due to long processing times, it is difficult to actually use these methods. Processing small amounts of zeolite has major disadvantages and is not a good idea.

Furthermore, the present inventors treated natural zeolite with an acid under normal pressure and observed changes in its properties, as described in the comparative example below.

As a result, acid treatment causes collapse of the zeolite structure,
It was found that the adsorption performance actually decreased.

The present invention provides a modification treatment method that improves the above-mentioned drawbacks of natural zeolite and imparts adsorption capacity and properties comparable to those of synthetic zeolite.

Furthermore, the present invention provides a method for modifying natural zeolite, which does not have the drawbacks of the conventional methods described above.

According to the method of the present invention, natural zeolite containing clinoptilolite and mordenite as main components is treated with an alkaline aqueous solution under suitable conditions in an autoclave offshore, and modified to have adsorption capacity and properties comparable to synthetic zeolite. Zeolite is obtained.

Generally, the zeolite content in natural zeolite ore is 80-90% even if it is of good quality, and the remaining 10-20% is impurities such as tuffaceous glass.

The main components of the natural zeolite used in the present invention are clinoptilol zeolite and mordenite, and the chemical composition of the former is Ca(Na,K)4AZ6Si3oO7224H20
1 The latter is (Na, K)2 CaAJI? 2StI00
24 @7H20.

Among natural zeolites, clinoptilolite has a higher content, but both of these are high-silica, high-alkali minerals.

The composition of the above natural zeolite is, for example, 5iO278
%, A120313%, R20 (20 to Na20+)6
．． It is 8%.

In the modification treatment method of the present invention, natural zeolite is first dried, pulverized, and sized using a general method, and the diameter is 0.1 to 2 m/m.
The grain size is

An appropriate amount of alkaline aqueous solution is added to this natural zeolite, and the mixture is sent into an autoclave for treatment.

Suitable alkaline aqueous solutions include sodium hydroxide, potassium hydroxide, calcium hydroxide, and ammonium hydroxide, with sodium hydroxide being particularly suitable.

The use of sodium hydroxide has the advantage that sodium has a better replacement efficiency with exchangeable metal ions contained in the zeolite than the other metal hydroxides mentioned above.

Furthermore, when the zeolite is modified with an aqueous sodium hydroxide solution, the sodium in the zeolite can easily replace the metal ions in the object to be treated during actual use.

The treatment method of the present invention is carried out under pressurized hot water as described above, and the preferred pressure is 2 to 4 kg/cyyt (gauge).
It is.

When the pressure exceeds 4 kg/crit (gauge), the temperature also naturally increases, which changes the crystal structure of the natural zeolite and reduces its adsorption capacity.

In addition, since the pressure is less than 2 kg/crit (gauge) and the temperature is low, the reaction is slow and the processing time is long.
This will require 00 HR.

According to the method of the present invention, impurities in the zeolite can be removed, and the exchangeable metal ions in the zeolite are replaced by IJium (Na) and crystals of clinoptilolite are grown, improving adsorption performance. can be done.

The method of the invention is preferably carried out as follows.

Weigh a predetermined amount of the zeolite sample, mix NaOHO, 1 to 5 (N) as an alkaline aqueous solution in a range of 1 to 10 parts per part of the zeolite, and add 2 to 4 kg/crI.
The treatment is carried out at a pressure of t (gauge) and 1 to 5 HR.

At this time, stirring is performed at 1 to 20 RPM so that the zeolite and the alkaline aqueous solution come into good contact.

The treated zeolite is thoroughly washed with water to remove excess alkaline content, and the lachrymal fluid is washed with pH 9 or less.
The product is dried at about 70 to 140°C.

In this case, depending on the reforming conditions, the zeolite may be slightly powdered and its particle size may become smaller, and in this case it is also necessary to classify it using an appropriate sieve.

For example, the autoclave pressure is 2. Okg/cyrt
(gauge), the adsorption performance of the modified zeolite when 10 parts of zeolite is mixed with 40 parts of alkaline liquid and subjected to 3HR treatment is as shown in Figure 1.

As shown in FIG. 1, the cation exchange capacity (CEC) of the modified zeolite according to the present invention is 150 meq when treated using 0.1N to 5N sodium hydroxide.
/100 g zeolite or more, its adsorption performance is found to be improved compared to untreated natural zeolite whose CEC is 100 to 150 meq/100 g zeolite.

Cation exchange capacity (CEC) is used to measure the properties of zeolites in terms of adsorption performance, and there are many methods for measuring this, but the most representative one is Scholenberger (5chol).
fen-berger) method and Shawfield (5
chofield) method.

The measurement method used in this specification is to apply ammonium ions (N
H4+) is adsorbed, this is exchanged with potassium ions (K0), and the desorbed NH4+ is analyzed by the Kjeldahl method and CEC
was measured.

Generally, the CEC of natural zeolite is 100 to 150 me.
q/100 gr zeolite, synthetic zeolite (
molecular sheep) is 250-350meq/10
It was confirmed that the modified zeolite according to the present invention had an excellent adsorption property of 190 to 300 meq/100 gr zeolite.

Under such reforming conditions, if the alkali concentration is high,
The clinoptilolite crystals disintegrate or shift, and their adsorption performance decreases.

Under the above modification conditions, the alkali concentration is preferably 0.1 to 5N, and the best is 1 to 2N, and the alkali content is 1.6% to 80% (by weight), respectively, per unit zeolite.
16% to 32% (by weight).

As described above, in the method of the present invention, the alkali concentration is low, the reaction time is short, and the water washing process after modification is easy.Moreover, the adsorption performance of the modified zeolite is high because the exchanged metal ions are sodium, Compared to treated zeolite, it is characterized by good performance over a wide concentration range of adsorbed substances.

The modified zeolite obtained by the method of the present invention has significantly improved adsorption performance, and as shown in Table 1 (see below), the modified zeolite has a significantly improved adsorption performance compared to untreated natural zeolite, as determined by the measurement of zeolite crystals by X-ray diffraction method. The overall diffraction intensity of quality zeolite is stronger, especially d = 8.99, 3.97.
The relative intensities of 3 and 3 and 17 were strong, and it was also confirmed by electron microscopy that impurity removal and crystallinity were improved.

Furthermore, the modified zeolite maintains the structure of natural zeolite without collapsing it.

The composition of the zeolite modified by the method of the present invention is S
55-75% as i02, 14-2 as Al2O3
6%, 7.5 to 13 as R20 (20 to Na20+)
% range, and this can be compared to the composition of untreated natural zeolite, i.e. 78% SiO2 and 13% Al2O3.
, R206.8%, the S t 02 content of the modified product decreased, the Al2O3 content increased, and the R20 as alkali content also increased.

Especially when the composition of the modified zeolite falls within the above range,
The increase in adsorption performance is significant.

In actual adsorption tests for ammonium ions (NH4'') and various heavy metal ions, when comparing untreated natural zeolite and modified zeolite, the latter had 2 to 3 times the ability to absorb heavy metal ions using CEC. It was confirmed that the adsorption capacity was 1.5 to 3 times higher.

The modified zeolite obtained by the present invention has excellent adsorption performance, so it can be used as an adsorbent for drying (drying of gases and liquids) and purification (drying of gases and liquids), which is the field in which synthetic zeolite is used industrially. Desulfurization, decarbonation gas, hydrogen gas purification,
It can be used in processes such as production of oxygen, etc.) and separation (separation of N-paraffins, separation of N-olefins, separation of p-xylene, etc.).

Furthermore, the modified natural zeolite produced by the method of the present invention is characterized by far superior acid resistance compared to synthetic zeolite.

For example, synthetic zeolite (Molecular Sieve 10X)
When treated with 0.5N hydrochloric acid at 30°C, the structure collapses (as confirmed by X-ray diffraction), and the CEC also becomes 0.

On the other hand, the modified natural zeolite according to the method of the present invention has a 0.
The zeolite structure remains even when treated with 5N to 12N hydrochloric acid at 30°C, and the CEC is 0.5N and 15 when treated with hydrochloric acid.
6 meq/1009r Zeolite 125 meq/Zo even when treated with 12N hydrochloric acid.

Shows good adsorption performance with gr zeolite.

Examples and reference examples of the present invention will be described below.

Reference Example 1 10 parts of clinoptilolite natural zeolite sized to 0.1 to 1 m/m, 0. IN sodium hydroxide 100
The mixture was mixed and subjected to pressurized hot water treatment in an autoclave at 1.5 kg/i (gauge) with stirring at 5 HR and 10 RPM.

After the treatment, the zeolite was washed with water and filtered, and washing was continued until the pH of the F solution became 8. The zeolite was dried at 70° C. for 3 hours to obtain a modified zeolite.

The crystals of the modified zeolite obtained by the present invention have good X-ray diffraction values as shown in Table 1 (described later), and Table 2 (described later).
It has good properties as shown in (described later).

Example 1 10 parts of clinopti zeolite natural zeolite sized to 0.5 to 1.5 m/m and 40 parts of IN sodium hydroxide were mixed and heated in an autoclave at 3.5 kg/crit (gauge) for 3 HR. The same treatment as in Reference Example 1 was carried out to obtain a modified zeolite.

The X-ray diffraction values of the obtained modified zeolite are shown in Table 1, and the properties are shown in Table 2.

The modified zeolite has good X-ray diffraction values and properties.

Reference Example 2 10 parts of clinoptilol natural zeolite sized to 0.5 to 2 m/m and 40 parts of 2N sodium hydroxide were mixed, and the mixture was placed in an autoclave at 5.5 kg/crA (gauge).
The same treatment as in 3HR1 Reference Example 1 was carried out to obtain a modified zeolite.

Tables 1 and 2 show the X-ray diffraction values and properties, respectively.

The obtained modified zeolite has excellent X-ray diffraction values and properties.

Table 1 shows the relative intensities of the X-ray diffraction peaks of clinoptilolite-based natural zeolite, and the numerical value was calculated by setting the intensity of untreated natural zeolite at d = 8.99 as 100.

Comparative Example In this comparative example, natural zeolite was treated with acid under normal pressure.

Natural zeolite was dried, pulverized, and sized to have a particle size of about 0.1 to 2 m/m in diameter by a general method.

Take this as 10 (J'r) and get 0.5, 1, 2°5 respectively.
Add 100rrLl of hydrochloric acid of ,10,12(N) to 30
6HR normal pressure treatment was carried out at 70°C and 70°C.

As a result, as shown in Figure 2, the zeolite structure collapsed and the adsorption performance decreased.

This has also been confirmed by X-ray diffraction.

Therefore, it is impossible to remove impurities in zeolite by hydrochloric acid treatment, and the properties of zeolite cannot be improved by this treatment.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the adsorption performance of modified zeolite obtained by the treatment method of the present invention. FIG. 2 is a graph showing the adsorption performance of natural zeolite when it is acid-treated under normal pressure.

Claims (1)

[Claims] 1. Natural zeolite containing clinoptilol zeolite and mordenite as main components in an alkaline aqueous solution with a concentration of 2 to 4 k
A method for modifying natural zeolite, which comprises subjecting it to hot water treatment under a pressure of g/crlL (gauge) to improve the adsorption performance and acid resistance of the natural zeolite. 2. The treatment method according to claim 1, wherein the alkaline aqueous solution is an aqueous solution of sodium hydroxide, potassium hydroxide, calcium hydroxide, or ammonium hydroxide. 3. The treatment method according to claim 1, wherein the alkaline aqueous solution is an aqueous solution of sodium hydroxide. 4. The treatment method according to claim 3, wherein the alkaline aqueous solution has a concentration of 0.1 to 5 normal. 5. The treatment method according to claim 3, wherein the alkaline aqueous solution has a concentration of 1 to 2 normal.