JPH11343113A - Low silica faujasite type zeolite and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a high-purity low-silica faujasite type zeolite (LSX) on a large scale in a short time. SOLUTION: When an aluminate-contg. soln. is mixed with a silicate-contg. soln. and gelation, aging and crystallization are carried out to produce LSX having an SiO2 to Al2 O3 molar ratio of 1.9-2.1, a soln. having a compsn. of the formula 10-20Na2 O.Al2 O3 .5-20SiO2 .100-250H2 O aged at 10-60 deg.C for 10 min to 3 hr is added by 0.001 to <0.03% (expressed in terms of Al2 O3 ) of the amt. of the formed LSX after the gelation or in the early stage of the aging or the soln. is added by 0.01-10.0% before the gelation to obtain the objective LSX having a faujasite single phase in X-ray diffraction, an SiO2 to Al2 O3 molar ratio of 1.9-2.1 and 1.0 to <10.0 μm primary particle diameter. The amt. of water adsorbed on the LSX is >=35.0% in the case of Na type.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a SiO ₂ / SiO ₂ separator which is excellent as a zeolite adsorbent for separating and concentrating oxygen from a mixed gas of oxygen and nitrogen by an adsorption method. Al ₂ O ₃ molar ratio of 1.9
Low-silica faujasite-type zeolites of 2.1 to 2.1 and a method for producing the same.

[0002]

_2. Description of the Related Art The SiO ₂ / Al ₂ O ₃ molar ratio is from 1.9 to
Various methods have been disclosed for the method for producing the low silica faujasite type zeolite (hereinafter referred to as “LSX”) of 2.1. For example, JP-A-53-8400 discloses that a mixture containing sodium, potassium, aluminate, and silicate is crystallized at a temperature of 50 ° C. or less, or extremely at a temperature of 50 ° C. or less for 15 to 72 hours. A method of aging for a long time and then crystallizing in a temperature range of 60 to 100 ° C is disclosed.

ZEOLITES, Volume 7, Septemb
er, pp. 451-457 (1987),
iO ₂ / Al ₂ O ₃ molar ratio, K / (Na + K) molar ratio,
The effects of alkali concentration, aging conditions, and crystallization conditions on the production of low silica faujasite type zeolite are disclosed in detail, and aging and crystallization are performed in a sealed plastic container.

Further, Japanese Patent Publication No. 5-25527 discloses that
Mixing a mixture containing sodium, potassium, aluminate and a mixture containing silicate at a low temperature of 4 to 12 ° C.,
It discloses a method of gelling, then aging this gel at 36 ° C. for 48 hours, and then raising the temperature to 70 ° C. for crystallization.
It is stated that cooling in the final mixing and avoidance of excessive mechanical energy is important.

As described above, low-silica faujasite-type zeolites are produced by mixing a solution containing sodium, potassium, aluminate and silicate at a low temperature and gelling, and then aging for a long time in a standing state. However, it has been considered that it is essential to raise the temperature to the crystallization temperature and to crystallize in a still state. However, it is industrially disadvantageous to cool raw materials to low temperatures, and gels have extremely poor heat transfer characteristics, so in large-scale synthesis, it is necessary to allow the temperature to remain uniform for a very long time. There was a difficulty that needed.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-purity LSX in the background described above, and furthermore, a method for synthesizing the LSX in a short time, and particularly a method for synthesizing a high-purity LSX. An object of the present invention is to provide a method for manufacturing on a large scale in a short time.

[0007]

Means for Solving the Problems The present inventors have intensively studied a method for synthesizing high-purity LSX in a short time, particularly a method for synthesizing high-purity LSX on a large scale, continuously and stably. As a result, the following points were found and the present invention was completed. That is, a solution containing aluminate and a solution containing silicate are mixed, gelled, and then aged and crystallized, so that the molar ratio of SiO ₂ / Al ₂ O ₃ is 1.
In the method for producing a low silica faujasite type zeolite of 9 to 2.1, 10 to 20 Na ₂ O · Al ₂ previously aged at a temperature of 10 ° C. to 60 ° C. for 10 minutes to 3 hours. O ₃ · 5~20SiO ₂ · 10
By adding a solution having a composition of 0 to 250 H ₂ O by the end of ripening, highly pure LS can be obtained in a very short ripening time.
It has been found that X can be synthesized, and the present invention has been completed.

Although the low silica faujasite type zeolite of the present invention has a theoretical SiO ₂ / Al ₂ O ₃ molar ratio of 2.0, it may be considered in consideration of measurement errors in chemical composition analysis. It is clear that low silica faujasite type zeolites having a composition of 1.9 to 2.1 fall within the scope of the present invention.

Hereinafter, the present invention will be described in detail.

[0010] The first invention of the present invention relates to a single phase of faujasite in X-ray diffraction method, wherein SiO ₂ / Al ₂
The O molar ratio is 1.9 to 2.1, the amount of water adsorbed in the case of Na type is 35.0% or more, and the primary particle diameter is 1.0 μm or more and less than 10.0 μm. It is a characteristic low silica faujasite type zeolite.

It is common practice to use X-ray diffraction to determine the purity of zeolite. The impurities by-produced during the synthesis of LSX include A-type zeolite, sodalite, and Breck "Zeolite Molecular".
Sieves "Krieger 1974, page 144, F-type zeolite, page 356, E-type zeolite, and the like. One of the features of the high-purity LSX in the present invention is that it is a single phase of faujasite in the X-ray diffraction method and does not contain the above-mentioned impurities.

However, when the crystallinity of the impurities is poor or when a plurality of trace impurities exist, the impurity peaks do not appear in the X-ray diffraction method even if the purity is slightly reduced.
The single phase of faujasite in X-ray diffraction is only one of the requirements for characterizing high purity.

On the other hand, the amount of water absorbed by pure zeolite shows a constant value depending on the type of zeolite and the type of cation. For example, sodium-type zeolite adsorbs 28 g of water per 100 g of zeolite, and sodium-type zeolite absorbs 27 g of water per 100 g of zeolite.
Adsorb water. On the other hand, sodium-type LSX adsorbs 36 g of water per 100 g of zeolite, and has a larger amount of water adsorption than zeolite, which easily occurs as an impurity. Therefore, the purity of the synthesized LSX can be estimated based on the amount of absorbed water. The high purity LSX in the present invention is
The X-ray diffraction method is characterized in that not only a single phase of faujasite but also a water adsorption amount of Na type is 35.0% or more, more preferably 35.5% or more.

The zeolite was converted to a scanning electron microscope (hereinafter referred to as S
When observed by EM), it exists as primary particles which are the minimum unit of zeolite particles, or as secondary particles in which a plurality of primary particles are aggregated. Generally, the shape of primary particles of zeolite is determined by its type. For example, A
The type zeolite is cubic, and the faujasite type zeolite has the shape of an octahedron or a spherical polyhedron with developed corners.

Usually, the particle size of these particles has a distribution centered on a certain value. The method for obtaining the average particle size from the particles having a distribution is described in detail, for example, in Shigeo Miwa, “Introduction to Powder Engineering,” Nikkan Kogyo Shimbun, 1981, pp. 1-30. The primary particle diameter in the present invention is defined as a number average particle diameter of the diameter of a primary particle of a faujasite type zeolite observed by SEM which approximates a sphere.

The LSX of the present invention is characterized by not only high purity but also its primary particle size. The primary particle size of the LSX of the present invention is 1 μm or more and less than 10 μm.

Next, a method for producing the low silica faujasite type zeolite of the present invention will be described.

In the present invention, a method of mixing, gelling, aging and crystallization a solution containing an aluminate and a solution containing a silicate to produce LSX includes sodium,
A solution containing each ion of potassium, aluminate and silicate was adjusted to have a viscosity of 10 to 10,000 after gelation was started.
ripening while maintaining at cp, or crystallization afterwards, or a solution containing aluminate and a solution containing silicate are mixed and gelled at a temperature of 20-60 ° C. It is desirable to use a method in which a slurry of 10,000 cp is prepared, aged, and then crystallized. This is because it is difficult to synthesize LSX under conditions that are industrially advantageous and can easily be scaled up by other than this method.

The present inventors have studied to synthesize LSX in a short time, and as a result, in the above-mentioned method, aging was performed at a temperature of 10 ° C. or more and 60 ° C. or less for 10 minutes or more and 3 hours or less. Performed 10-20 Na ₂ O · Al ₂ O
A solution having a composition of _{3 · 5~20SiO 2 · 100~250H 2 O} , by adding up to completion of the aging, found that generation LSX in a very short ripening time, and completed the present invention. In the present invention, 10 to 20
_{Na 2 O · Al 2 O 3} · 5~20SiO 2 · 100~250
A solution having a composition of H ₂ O is used simply for “added solution”.

The composition of the "solution to be added" is 10-20 Na
_{2 O · Al 2 O 3 ·} 5~20SiO 2 · 100~250H 2
It is essential to be in the range of O. If the composition of the solution to be added is out of this range, a long aging time is required to synthesize high-purity and fine LSX, which is not preferable, and impurities may be easily generated.

The "solution to be added" must be aged at a temperature of 10 ° C. or more and 60 ° C. or less for 10 minutes or more and 3 hours or less. Proc. 7th Int Conf. Zeoli
tes, pages 185-192 1986, it is considered that fine X-type zeolite fine crystals having a SiO ₂ / Al ₂ O ₃ molar ratio of about 2.4 are formed. Although the cause is unknown in the present invention, such fine X-type zeolite microcrystals contained in the “solution to be added” perform some action, and can synthesize high-purity LSX in a short time of maturation. It is estimated that

The present inventors have conducted detailed studies on the timing and amount of the "solution to be added" and found the following points.

The "solution to be added" may be added at any time as long as it is before the end of the ripening, but also in the aging step when the gelation is completed or when the formed gel is ripened. It may be added at the beginning of or before gelation.

When the "solution to be added" is added after the gelation, that is, when the mixing of the solution containing the aluminate and the solution containing the silicate is completed, it is most preferable to add the solution immediately after the gelation. The delay of addition is not a problem, and it is added after completion of gelation or at the beginning of the aging step when aging the formed gel. As a result of a detailed study on the amount of the “solution to be added” at this time, it was found that the effect was shown to be smaller than that of a very small amount. If the amount of the “solution to be added” is 0.001% or more based on Al ₂ O ₃ based on the low-silica faujasite-type zeolite to be produced, a high-purity LSX can be synthesized in a short aging time, The amount of the "solution to be added" is 0.001% or more and less than 0.03%. Even if the amount of “solution to be added” is less than 0.001%, L
Although it is possible to synthesize SX, the effect is insufficient for the purpose of the present invention, that is, to obtain high-purity LSX in a short aging time.

It is also possible to add the “solution to be added” before the gelation. For example, a method of adding an "added solution" to one or both of a solution containing aluminate or a silicate as a raw material, gelling and then aging, or adding an "added solution" to a reaction vessel in advance A method of mixing a solution containing aluminate and a solution containing silicate is exemplified. As a result of a detailed study on the amount of the “solution to be added” at this time, it was found that the effect was shown to be smaller than that of a very small amount. When the amount of the “solution to be added” is 0.01% or more based on Al ₂ O ₃ based on the generated low silica faujasite type zeolite, a high-purity LSX can be synthesized in a short aging time,
0.01% or more and 10.0% of the "solution to be added"
It is as follows. Although it is possible to synthesize LSX even when the amount of the “solution to be added” is less than 0.01%, the gist of the present invention is as follows.
That is, the effect is insufficient to obtain high-purity LSX in a short aging time. Further, when the amount of the “solution to be added” exceeds 10.0%, when industrially producing LSX, a large-scale input facility is required, which is not only practical, but also the composition of the obtained LSX is SiO ₂ / The molar ratio of Al ₂ O ₃ may not be 1.9 to 2.1, which is not preferable.

After adding the "solution to be added", aging is continued. The aging may be performed in either a stationary state or a stirring state, but the gist of the present invention, namely, high purity LSX
Is required to be performed in a stirring state in order to obtain a short aging time. This is because, when aging is performed in a stationary state, a long aging time is required to obtain high-purity LSX. According to conventional knowledge, it has been considered that ripening and crystallization must be performed in a state of standing or in a state close to standing.
However, in the present invention, the tendency is completely opposite to this finding, that is, the stronger the agitation at the time of aging, the easier it is to produce high-purity LSX, and the short-term aging that was impossible with the prior art. It becomes possible to obtain LSX in time. In the present invention, stirring during ripening can be performed using a generally known stirring blade such as a propeller, a turbine, or a paddle. The stronger the stirring, the better, and it is not preferable that there is at least a stagnation portion of the slurry in the reaction tank. The specific stirring strength can be expressed using “power required for stirring per unit volume of slurry: unit kW / m ³ ” defined by chemical engineering, and at least 0.1 kW / m ^3. The above stirring intensity is required, preferably 0.2 kW / m ³ or more, more preferably 0.4 kW / m ³ or more, and further preferably 0.8 kW / m ³ which is called strong stirring in chemical engineering. It is desirable to perform ^three or more agitation. The stronger the stirring, the better. However, a strong motor requires a powerful motor. For example, an industrially possible 3.0 kW /
About m ³ can be exemplified as the upper limit of the power required for stirring per unit volume of the slurry. The aging time in the present invention cannot be uniquely determined because it varies depending on the timing and amount of the `` solution to be added '', the temperature during aging, the stirring intensity, etc., but the gist of the present invention, namely, high purity In view of providing a method for synthesizing LSX in a short time, a long aging time is meaningless and is preferably at least 24 hours or less, more preferably 15 hours or less, and further more preferably 12 hours or less. Ripening time. Also, surprisingly, when the present invention is used, a high-purity LSX is synthesized in the conventional synthesis of LSX.
Aging time, which has been considered impossible to obtain, i.e., 0.5 h or more and 10 h or less, depending on the amount of solution to be added, the aging temperature and the stirring intensity, high purity LSX can be obtained.
Can be synthesized.

Next, the slurry aged for a predetermined time is heated to a crystallization temperature. LSX is easily produced from the slurry aged by the method of the present invention, and the temperature can be raised by any method generally known. In a laboratory, the temperature may be raised together with the water bath containing the reaction vessel while stirring, or the temperature may be raised by placing the reaction vessel in a drier or the like that maintains the reaction vessel at a predetermined temperature. In the case of a plant, a normal operation known in chemical engineering, for example, steam or heat medium is transferred to a heat exchanger such as a jacket attached to the reaction vessel while stirring is continued to improve heat transfer. Can be exemplified. The time required for the temperature rise is not particularly limited, and may be, for example, 0.5 to 5 hours.

From the slurry aged by the method of the present invention, high-purity LSX is likely to be produced, and the crystallization is not required to be carried out by crystallization under stirring. Good, or may be performed in a stationary state. As the crystallization temperature, a conventionally known crystallization temperature of LSX can be used, and for example, a temperature of 60 to 100 ° C. can be exemplified. The crystallization time is not constant depending on the aging conditions, composition and crystallization temperature, but about 2 to 12 hours is sufficient, and longer time may be used.

The SiO ₂ / A produced as described above
A high purity, fine, low silica faujasite type zeolite having a l ₂ O ₃ molar ratio of 1.9 to 2.1 is filtered, washed and dried. Known methods can be used as the method of filtration, washing, and drying.

The LSX obtained by the method of the present invention is formed into, for example, spherical or columnar pellets using a clay binder or the like, then exchanged with Li ions or Ca ions, and activated at 400 ° C. for about 1 hour. If it becomes an adsorption separation agent with high adsorption performance, its excellent gas adsorption performance,
Particularly, since it is excellent in nitrogen adsorption performance, it is suitably used as a zeolite adsorption separating agent for separating and concentrating oxygen from a mixed gas of oxygen and nitrogen by an adsorption method.

[0031]

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to only these examples. In addition, each measuring method in an Example is as follows.

(1) Method of measuring chemical composition After dissolving a sample using nitric acid and hydrofluoric acid, an ICP emission spectrometer (Perkin Elmer, model: optima 3)
000), Na, K, Al, and Si were measured, and these were calculated by converting them to Na ₂ O, K ₂ O, Al ₂ O ₃ , and SiO ₂ , respectively.

(2) Method of measuring crystal structure X-ray diffractometer (manufactured by Mac Science, model: MXP-
It measured using 3). (3) Observation method of particles Scanning electron microscope (manufactured by JEOL Ltd., model: JSM
-T220A, hereinafter abbreviated as SEM).

(4) Method of Measuring Adsorbed Amount of Water Equilibrium The powder dried at 100 ° C. was left in a desiccator at a relative humidity of 80% for 16 hours or more, and heated at 900 ° C. for 1 hour for measurement. That is, the weight after moisture adsorption is X ₁ and this is 90
The weight after ignition at 0 ° C. for 1 hour is defined as X ₂ , and the water equilibrium adsorption amount (%) is obtained from the following equation.

Water equilibrium adsorption (%) = ｛(X ₁ −X ₂ ) /
X ₂ ｝ × 100 (5) Ion exchange method to Na type LSX ZEOLITES, Volume 7, September, 456
Page (1987). 1 mol / L prepared by adding sodium hydroxide to pH = 12
Of sodium chloride was added so that the amount of sodium chloride became 1 mol per 1 mol of LSX, and ion exchange was performed at room temperature in a batch system. This operation was performed five times.

Example 1 Preparation of "solution to be added" A sodium aluminate aqueous solution (Na ₂ O = 20.0% by weight,
36 g of Al ₂ O ₃ = 22.5% by weight), 66 g of sodium hydroxide (purity: 99%) and 120 g of pure water were added and dissolved by stirring, and kept at 40 ° C. using a water bath. 3 in this solution
No. sodium silicate aqueous solution (Na ₂ O = 9.3% by weight,
(SiO ₂ = 28.9% by weight)
Aging was performed for 0 minutes. At this time, the composition of the “solution to be added” is 15.0Na ₂ O · Al ₂ O ₃ .10.0 SiO ₂ .180
H ₂ O.

Synthesis of LSX A sodium silicate aqueous solution (Na ₂ O = 3.8% by weight, SiO ₂ = 1) was placed in a stainless steel reaction vessel having an internal volume of 3 liters.
896 g of water (2.6% by weight), 777 g of water, 231 g of sodium hydroxide (purity: 99%), and 455 g of an aqueous solution of potassium hydroxide for industrial use (purity: 48%) were stirred at 250 rpm, and kept at 40 ° C. using a water bath while stirring at 250 rpm. 25 g of "solution to be added" was added. At this time, the amount of the “solution to be added” is 0.5% by weight based on Al ₂ O _{3 based} on LSX to be generated. An aqueous solution of sodium aluminate (Na ₂ O = 20.0% by weight, A
(462 g) (1 ₂ O ₃ = 22.5% by weight) was charged over 1 minute. Immediately after the addition, the mixture became cloudy and gelation started. Immediately before the end of the charging, the viscosity of the whole gel increased, and although the gel almost started to stagnate at the upper part of the reaction vessel, the whole fluidized uniformly after about one minute. The stirring was continued at 250 rpm and the
Aging was performed at 0 ° C. for 4 hours. When the required power for stirring per unit volume of the slurry during aging was calculated based on the torque applied to the stirring motor, it was 0.4 kW / m3.

After aging, the temperature was raised to 70 ° C. over 1 hour while stirring was continued. After the temperature was raised, the stirring was stopped, and crystallization was performed at 70 ° C. for 4 hours. The obtained crystals were filtered, sufficiently washed with pure water, and then dried at 70 ° C. overnight.

The structure of the obtained crystal powder was a faujasite-type zeolite single phase as a result of X-ray diffraction, and the chemical composition thereof was found to be 0.72 Na ₂ O ·
A _{0.28K 2 O · Al 2 O 3} · 2.0SiO 2, the equilibrium water adsorption was 33.4%.

As a result of observing the obtained powder by SEM, it was found that the primary particle diameter was 2.0 μm LSX. The SEM photograph (magnification = 5000 times) is shown in FIG.

In addition, ion exchange with Na type was performed, and the amount of adsorbed water was determined to be 35.9%.

Example 2 Synthesis of LSX A sodium silicate aqueous solution (Na ₂ O = 3.8% by weight, SiO ₂ = 1) was placed in a stainless steel reaction vessel having an inner volume of 20 liters.
(2.6% by weight) 7350 g, water 6000 g, sodium hydroxide (purity 99%) 1850 g, and industrial potassium hydroxide aqueous solution (purity 48%) 3570 g, and 100 rpm.
The temperature was kept at 40 ° C. using a water bath while stirring.
To this solution, 3666 g of an aqueous solution of sodium aluminate (Na ₂ O = 20.0% by weight, Al ₂ O ₃ = 22.5% by weight) kept at 40 ° C. was added over 1 minute. Immediately after the addition, the mixture became cloudy and gelation started. Immediately before the end of the charging, the viscosity of the whole gel increased, and although the gel almost started to stagnate at the upper part of the reaction vessel, the whole fluidized uniformly after about one minute. When the entire slurry was uniformly fluidized, 7.8 g of “addition solution” prepared in the same manner as in Example 1 was added. At this time, the amount of the “solution to be added” is
0.02% based on Al ₂ O ₃ . 100 rp as it is
m, and aged at 40 ° C. for 4 hours. When the required power per unit volume of the slurry during aging was calculated based on the torque applied to the stirring motor, 0.2 kW was obtained.
/ M3.

After aging, the temperature was raised to 70 ° C. over 1 hour while stirring was continued. After the temperature was raised, the stirring was stopped, and crystallization was performed at 70 ° C. for 4 hours. The obtained crystals were filtered, sufficiently washed with pure water, and then dried at 70 ° C. overnight.

The structure of the obtained crystalline powder was a single phase of faujasite-type zeolite as a result of X-ray diffraction, and the chemical composition thereof was found to be 0.72 Na ₂ O ·
A _{0.28K 2 O · Al 2 O 3} · 2.0SiO 2, the equilibrium water adsorption was 33.2%.

As a result of observing the obtained powder by SEM, it was found that the primary particle diameter was 1.1 μm LSX. The SEM photograph (magnification = 5000 times) is shown in FIG.

Further, ion exchange with Na type was performed, and the amount of adsorbed water was determined to be 36.1%.

Comparative Example 1 An aqueous sodium silicate solution (Na ₂ O = 3.8% by weight, SiO ₂ = 1) was placed in a stainless steel reaction vessel having an internal volume of 3 liters.
917 g of water (2.6% by weight), 749 g of water, 231 g of sodium hydroxide (purity 99%), and 446 g of an aqueous solution of potassium hydroxide for industrial use (purity 48%) were added and kept at 40 ° C. using a water bath while stirring at 250 rpm. To this solution was added an aqueous solution of sodium aluminate (Na ₂
O = 20.0% by weight, Al ₂ O ₃ = 22.5% by weight) 45
8 g was charged over 1 minute. Immediately after the addition, the mixture became cloudy and gelation started. Immediately before the end of dosing, the viscosity of the entire gel increases,
Although the gel was partially stagnated at the top of the reaction vessel, the whole fluidized uniformly after about 1 minute. As it is 250
Stirring was continued at rpm, and aging was performed at 40 ° C. for 4 hours. After aging, the temperature was raised to 70 ° C. over 1 hour while continuing stirring. After the temperature was raised, the stirring was stopped, and crystallization was performed at 70 ° C. for 4 hours. After filtering the obtained crystals and washing them thoroughly with pure water,
Dry at 70 ° C. overnight.

As a result of X-ray diffraction, the structure of the obtained crystalline powder was mainly composed of faujasite-type zeolite, and traces of A-type zeolite, F-type zeolite, E-type zeolite and an unidentified phase were observed. . As a result of composition analysis, the chemical composition was 0.73Na ₂ O · 0.27K ₂ O ·
Al ₂ O ₃ · 2.0 SiO ₂ , with a moisture equilibrium adsorption of 3
2.6%.

As a result of observing the obtained powder by SEM, an impurity phase was conspicuous other than LSX having a primary particle diameter of about 10 μm.

Further, ion exchange with Na type was performed, and the amount of adsorbed water was determined to be 34.9%.

Comparative Example 2 The same operation as in Comparative Example 1 was performed except that the aging time was changed to 24 hours.

The structure of the obtained crystalline powder was a faujasite-type zeolite single phase as a result of X-ray diffraction, and its chemical composition was 0.73Na ₂ O · 0.27K ₂ O · Al ₂
O ₃ · 2.0 SiO ₂ , with a water equilibrium adsorption of 33.3
%Met.

As a result of observing the obtained powder by SEM, a slight impurity phase was observed and the primary particle diameter was about 5 μm.
X.

Further, ion exchange with Na type was performed, and the amount of adsorbed water was determined to be 35.8%.

As shown in Comparative Examples 1 and 2, it is possible to obtain high-purity LSX by a method other than the method of the present invention, but the productivity is poor because long-term aging is required. .

[0056]

According to the present invention, high-purity LSX can be synthesized in a short time, and in particular, high-purity LS
X can be produced on a large scale in a short time, and is an industrially useful production method.

[Brief description of the drawings]

FIG. 1 is a SEM showing the crystal structure of the powder obtained in Example 1.
Is a photograph observed at a magnification of 5,000 times using the same method.

FIG. 2 is a SEM showing the crystal structure of the powder obtained in Example 2.
Is a photograph observed at a magnification of 5,000 times using the same method.

Claims (3)

[Claims] An X-ray diffraction method comprising a single phase of faujasite, a SiO ₂ / Al ₂ O ₃ molar ratio of 1.9 to 2.1, and a water adsorption of 35. 0% or more, and the primary particle diameter is 1.0 μm or more and 10.0 μm or more.
m, a low-silica faujasite-type zeolite characterized by being less than m. 2. A solution containing an aluminate and a solution containing a silicate are mixed, gelled, and then ripened and crystallized to obtain a SiO ₂ / Al ₂ O ₃ molar ratio of 1.9 to 2.
In the method for producing a low-silica faujasite-type zeolite according to 1 above, aging was performed in advance at a temperature of 10 ° C or more and 60 ° C or less for a time of 10 minutes or more and 3 hours or less.
_{0Na 2 O · Al 2 O 3} · 5~20SiO 2 · 100~25
A solution having a composition of 0H ₂ O was added to the resulting low-silica faujasite-type zeolite by 0.02% based on Al ₂ O _3.
2. The low silica fogger according to claim 1, wherein the compound is added after gelation or at an early stage of ripening, or added before gelation from 0.01% to 10.0%. A method for producing a site type zeolite. 3. The method for producing a low-silica faujasite-type zeolite according to claim 2, wherein stirring is performed during aging.