JPS61155215A - Synthesizing method of l-type zeolite by stirring - Google Patents

Abstract

PURPOSE:To synthesize a high-purity L-type zeolite with good reproducibility by treating previously >=10wt% raw material of silica and alumina in the aqueous solution of alkali metal hydroxides. CONSTITUTION:Ten or more wt% silica source and alumina source (based on the total amount) to be used for a reaction are prepared. This mixture is treated previously in the mixed aqueous solution of potassium hydroxide and sodium hydroxide. New silica source, alumina source, and alkali source are added to the treated silica source and alumina source to make a mixture which is crystallized by heating.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for synthesizing L-type zeolite, which belongs to zeolites having a C cage (canclinite cage).

(Prior Art) Several methods have been proposed so far for synthesizing L-type zeolite.

For example, in Japanese Patent Publication No. 36-3675, a potassium-containing mixture obtained by using an aqueous colloidal silica sol as a silica source is heated at a temperature of 100 to 200°C to
A method of obtaining L-type zeolite by crystallizing the rod while standing still for 169 hours has been proposed.

However, this method takes a long time to synthesize and the yield of silica is extremely poor, so it cannot be used as an industrial method for producing the side bottom.

Furthermore, Japanese Patent Publication No. 46-35604 has proposed an improved method of the above. Although this method is certainly improved in terms of silica yield, it requires the use of expensive reactive amorphous solid silica as the silica source, and it also Depending on the amount of
It's not something you can get.

In any case, these methods require expensive amorphous solid silica as the silica source and require a long crystallization time, making it difficult to economically produce L-type zeolite.

Furthermore, according to Japanese Patent Application No. 57-181408, high-purity L-type zeolite was produced with good reproducibility by crystallizing an amorphous compound obtained by reacting an aqueous solution of sodium silicate with an aqueous solution of aluminum sulfate in an aqueous potassium hydroxide solution. A method to obtain this is proposed.

This method synthesizes L-type zeolite in a short time using an aqueous sodium silicate solution, which is an inexpensive silica source, and improves the conventional disadvantages in economic and operational aspects.

However, all of these methods have fatal drawbacks in terms of reproducible synthesis on an industrial scale. This is because it is impossible to carry out the reaction by stirring and mixing the reaction system during its synthesis. In particular, if stirring and mixing is performed during the reaction process to convert the amorphous aqueous gel formed after mixing the raw materials into L-type zeolite, crystallization to L-type zeolite will be inhibited, and most of the product will be produced naturally. This results in a transition to aluminosilicate minerals that have no utility value, such as philipsite mineral analogues (hereinafter simply referred to as philipsite) or adralia. Therefore, in the synthesis of high-purity L-type zeolite, it has been essential to synthesize the aqueous gel-like reaction system under static conditions, avoiding stirring and mixing as much as possible. However, when this static synthesis is carried out on an industrial scale, heat transfer within the system becomes difficult because the stirring heat transfer necessary to maintain the reaction temperature must be avoided, resulting in undesirable effects due to temperature non-uniformity. In other words, as mentioned above, the reality is that filibsite and adlaria often coexist even in this static synthesis method.

[Problems to be solved by the present invention]

The purpose of the present invention is to provide a stirring synthesis method that can be applied to any raw material without being limited to a specific raw material, and can synthesize high-purity L-type zeolite on an industrial scale with good reproducibility. be.

[Means for solving problems]

The present inventors have proposed that when synthesizing L-type zeolite by heating and crystallizing a raw material mixture consisting of a silica source, an alumina source, and an alkali source, at least 10% by weight of the total amount of silica source and alumina source is used in the reaction. When the above is treated in advance in an aqueous alkali metal hydroxide solution under a specific temperature environment,
We have discovered that synthesis under stirring, which was previously impossible, can be easily performed. The present invention has been made based on this knowledge.

The details will be explained below.

[For production]

In the present invention, when synthesizing L-type zeolite by crystallizing a raw material mixture consisting of a silica source, an alumina source, and an alkali source, at least 10% by weight or more of the total amount of the silica source and alumina source used in the reaction is preliminarily mixed with an alkali metal hydroxide. It is essential to process in an aqueous solution at a temperature of 40 to 100°C.

Through the above-described treatment, the silica source and the alumina source are once dissolved in the aqueous alkali metal hydroxide solution, and a new amorphous aluminosilicate material, which is a precursor material of L-type zeolite, is formed. In the reaction process in which crystals of L-type zeolite are formed, the aluminosilicate material produced by the above treatment acts as a crystal nucleation agent, promoting the crystal formation of L-type zeolite at once, and at the same time inhibiting the symbiosis of impurities. This results in the production of highly pure L-type zeolite. Furthermore, it is truly surprising that highly pure L-type zeolite can be obtained with good reproducibility while stirring the reaction system, which was previously considered impossible.

The present invention will be explained in detail below.

The method of the present invention is applicable to all of the silica sources and alumina sources that constitute the reactant mixture for forming L-type zeolite known in the art. For example, as a silica source, aqueous colloidal silica sol, reactive amorphous solid silica, or an aqueous alkali silicate solution, which has been difficult to use in conventional methods, can be easily used in the present invention.

In addition, as an alumina source, an aluminum-containing aqueous solution, for example,
Any of aluminum sulfate, aluminum chloride, and sodium aluminum can be preferably used.

In addition, as the aqueous alkali metal hydroxide solution, a mixed aqueous solution of potassium hydroxide and IJium hydroxide is used, but if the above-mentioned alkali components are brought in from the silica source and alumina source used, the composition limited in the present invention may be used. The mixing ratio can be adjusted within the range.

In a known method, these raw materials are mixed in a specific composition range and then immediately heated to a predetermined temperature to effect crystallization.

In contrast, in the present invention, as described above, it is essential that at least 10% by weight of the total amount of the silica source and alumina source used be treated in a mixed aqueous solution of potassium hydroxide and sodium hydroxide. The composition range during the treatment is the following range expressed in terms of oxide molar ratio.

81~/1aoa = 10~20(%0-)-
N~O)/to 31' =0.25~1.0% O/
(zo + N ~ 0) = α5 ~ α9 gift 0 / (%O publication 10)
=11~40 Treatment temperature is 40~100℃, preferably 60~100℃
is within the range of If the above-mentioned treatment temperature is lower than 40° C., the formation of the aluminosilicate material that enables stirring synthesis, which is the object of the present invention, will be incomplete, and impurities such as filibsite will coexist.

On the other hand, if the treatment temperature is higher than necessary, impurities tend to coexist during stirring synthesis, which is not preferable, as in the case where the treatment temperature is too low.

The treatment time is determined by L of the silica source and alumina source to be treated in advance.
The time period varies depending on the proportion of the silica and alumina components to the total amount constituting the reactant mixture for forming the type zeolite, and ranges from 15 to 24 hours, preferably from 1 to 16 hours. A preferred embodiment of the treatment time is a short time when the above-mentioned ratio of silica source and alumina source to be pretreated is small, and a long time when the treatment ratio is large.

In addition, when the above-mentioned treatment ratio is less than 10% by weight, most of the added silica source and alumina source remain dissolved in the alkali metal hydroxide aqueous solution during the treatment, and the stirring synthesis aimed at the present invention cannot be achieved. No aluminosilicate material is formed that would allow for. As a result, when the reactant mixture prepared after mixing with the remaining silica source and alumina source is crystallized under stirring, impurities coexist, making it impossible to obtain high-purity L-type zeolite.

In the present invention, it is of course possible to treat all of the silica source and alumina source constituting the reactant layer compound in an aqueous alkali metal hydroxide solution, but in this case, as described above, long-term treatment is required. This increases the overall reaction time, including crystallization time. Therefore, in order to obtain L-type zeolite in a short reaction time, it is preferable that the above-mentioned treatment ratio is small, that is, the treatment ratio is in the range of 10 to 30% by weight. In this case, the preferable composition range during the treatment is expressed in terms of oxide molar ratio and falls within the following ranges.

(Preferred range) Z peak to Sl = 10 to 20 (K, O + Na2O)/s1o, = 0.4
~1. OKt O/(% O+M~Q)==15~0.
94o/(y, o+Na, o) = 11-30 (more preferable range) S1 body △], to = 10-14.5 (%O+Na2
O)/Si, = (14~0.8% O/(XO
+N~0)=0.6~α8 0/(%O+N~0)=2
0 to 30 Furthermore, in the present invention, it is possible to control the apparent particle size of the L-type zeolite produced by the above-mentioned treatment ratio. That is, the lower the treatment rate, the more L-type zeolite can be obtained in the form of coarse particles in which fine crystals are aggregated. In general, since L-type zeolite is obtained in a state where fine crystal particles with a diameter of 0.1 to 1.0μ are individually dispersed, it is difficult to perform industrial processing steps after crystallization, that is, filtration and washing. Therefore, a solution to this problem has been desired, but in the present invention, it is possible to obtain agglomerated particles of an appropriate size by adjusting the above-mentioned treatment ratio, thereby making the filtration and washing steps extremely easy. This is also one of the features of the present invention, in addition to the fact that stirring synthesis is possible, and its industrial significance is great.

After the above-mentioned treatment is completed, the remaining raw materials are added and mixed as necessary to prepare a reactant mixture for forming L-type zeolite, and then the crystallization step is started, but the composition of the reactant mixture is There are no particular limitations, and all composition ranges for obtaining conventionally known L-type zeolites are applicable.

The method of the present invention can be applied to all conventionally known silica sources and alumina sources for obtaining L-type zeolite, but the noteworthy point is that an inexpensive alkali silicate aqueous solution can be used as the silica source. .

For example, in the case where all the silica sources in the reactant mixture are alkali silicate, a preferable example is to use an amorphous aluminosilicate homogeneous phase compound obtained by simultaneously and continuously reacting an aqueous alkali silicate solution and an aqueous aluminum-containing solution. It is used as a source of silica as well as a source of alumina in a reactant mixture. In this method, an aluminosilicate homogeneous phase compound of any composition can be easily obtained by changing the supply ratio of the rainwater solution, so the composition can be freely set according to the purpose.

A more detailed explanation will be given below using representative examples.

The above-mentioned simultaneous and continuous reaction means an embodiment in which the aqueous alkali silicate solution and the aqueous aluminum-containing solution are supplied to the reaction zone simultaneously and while maintaining a substantially constant ratio.

As the aqueous alkali silicate solution, sodium silicate,
Various aqueous solutions such as potassium silicate are preferably used, and as aluminum-containing aqueous solutions, aqueous solutions of aluminum sulfate, aluminum chloride, sodium aluminate, etc. are preferably used.

A preferred embodiment for preparing an amorphous aluminosilicified salt homogeneous compound (hereinafter simply referred to as homogeneous compound) by this method is to prepare a rainwater solution under stirring in an overflow type reaction vessel equipped with a stirrer. This is a method of simultaneously and continuously supplying and reacting.

According to this method, the homogeneous compound produced is almost spherical, and most of the particle sizes are distributed in the range of 1 to 500μ, with the particle size being 1μ.
The following fine particles are extremely small.

As another example of the embodiment of homogeneous compound preparation, a so-called batch-continuous method of preparation may of course be applied, in which a rainwater solution is simultaneously and continuously fed at a constant ratio into a reaction tank under stirring conditions without discharging the reaction slurry. However, in this case, it is preferable to supply the rainwater solution over at least 10 minutes without adding it rapidly.

The characteristics of the homogeneous compounds obtained by these methods are that by simultaneously and continuously reacting rainwater solutions with adjusted concentrations at a fixed ratio, the composition of the homogeneous compounds produced is always constant, so there are no heterogeneous parts in the product. There is no such thing. As a result, when preparing a reactant mixture for forming L-type zeolite from these homogeneous compounds with a constant composition, at least 10% by weight of the homogeneous compounds are treated in advance in an aqueous alkali metal hydroxide solution to precipitate the reaction. If this is done, crystal formation will start all at once since there is no non-uniform portion of the composition in the reactant mixture, and coexistence of impurities due to the non-uniform portion of the reactant mixture can be prevented.

After the homogeneous compound has been filtered and washed once, it can be used in the form of a wet cake or after being slurried again in any desired state. Next, the homogeneous compound is treated in an aqueous alkali metal hydroxide solution, but the mixing order at this time is not particularly limited. It is preferable to add and mix the homogeneous compound into the metal aqueous solution, and conversely add the alkali metal hydroxide aqueous solution to the homogeneous compound slurry when the treatment ratio is large. After the treatment is completed, if a portion of the homogeneous compound has been treated, the remaining homogeneous compound and optionally the reactant mixture necessary to form the L-type zeolite are mixed with an aqueous alkali hydroxide Kanagawa solution. Adjust.

The reactant mixture that has been prepared is immediately heated and begins the crystallization process.

The crystallization temperature is 110-200°C. The time required for crystallization depends on the temperature, but is usually 15 to 40 hours.

After the crystallization is completed, the generated crystals are subjected to solid-liquid separation and washing to remove excess alkali remaining on the crystals, and then dried to obtain highly pure L-type zeolite.

The embodiment described above shows an example of a stirring synthesis method in which an aqueous alkali silicate solution, which has been difficult to use when synthesizing conventional zeolite, is used as the source of all silica. It is applicable to all conventional silica sources such as aqueous colloidal silica sol and reactive amorphous solid silica.

When these silica sources are used, stirring synthesis, which is the object of the present invention, becomes possible, and at the same time, the crystallization time can be greatly shortened.

〔Effect of the invention〕

As is clear from the above explanation, the present invention enables the stirring synthesis method of L-type zeolite, which was impossible with conventional methods, and as a result, it becomes possible to increase the size of the equipment, making it suitable for industrial use. High purity L-type zeolite can be produced economically on a large scale, and its industrial significance is great.

Furthermore, since the L-type zeolite obtained according to the present invention is obtained in high purity without the coexistence of impurities, it can be suitably used for various purposes, especially as a catalyst.

〔Example〕

Example-1' 21 liters of pure water was placed in an externally heated reaction tank equipped with a regular paddle-type stirrer.
was filled and maintained at 60°C.

Next, an aluminum sulfate aqueous solution (
AI, 01 =6.99w/v%, %S(1,==2
4.20W/v%) 1.4/ and sodium silicate aqueous solution (
Siol=15. OOw/v%, Na, O=4.93w
/v%, AI, t)g=Q, [17w/v%)5.6
t were simultaneously and continuously fed at a fixed ratio feed rate for 30 minutes and allowed to react under stirring. The reaction solution (slurry)
The pH was 7.0, and the reaction temperature was 60°C.

After the reaction is completed, the slurry product is separated into solid and liquid using a centrifugal separator, and washed with water until no SO4: ions are detected in the washing P solution, and Na, 0 = 2.4 on a wet basis.
7wt%, l, o, = 4. [l 6wt%, 5iC4
A homogeneous compound with a composition of =33.47 wt% was obtained.

Next, pure water 2169 was charged into an external heating reactor equipped with a regular paddle-type stirrer and a reflux condenser at the top.
* Add 155g of sodium hydroxide (98wt%) to 9
It was kept at 0°C.

Next, homogeneous compounds 57 & 59 were added and treated at 90° C. for 2 hours with stirring. The amount of the homogeneous compound corresponds to 15 wt% of the total amount of the homogeneous compound used in the reaction, and the composition during treatment was s
to, /A'34o, = 14. (%O+M%O)/S
i%=Q, 5,40/(K!0+Na1O)=α',)
It has an oxide molar composition of 40/(K!O+Na,O)=25. During the treatment, the added homogeneous compound was dissolved in the aqueous alkali metal hydroxide mixed solution and temporarily became a solution, but was then suspended again, and the mixture was in the form of a slurry upon completion of the treatment.

Next, pure water 9279. Potassium hydroxide (85.5wt
%) 314.5%, sodium hydroxide (98wt%) 1
4.69, which corresponds to 85 wt% of the total amount of homogeneous compounds.
A homogeneous compound of 13K59 was added to the slurry after the treatment was completed and stirred to prepare a reactant mixture.

Next, the reactant mixture was charged into an autoclave for 17
Crystallization was carried out under stirring at 0°C and its autogenous pressure for 20 hours. After the reaction was completed, the product was separated from the mother liquor by filtration, washed with water, and then dried at 110°C.

As a result of chemical analysis and X-ray diffraction, the product has a composition of 0.99 on an anhydrous basis! O-Q, 01Na, O”AI, Q, s&2
si% L-type zeolite. The powder X-ray diffraction pattern is shown in Figure 1.

The particle size of the L-type zeolite obtained was mostly 10~
It was an aggregate of 50μ.

In addition, after activating a part of the product in a McPain-Baker type adsorption device under vacuum at 350°C for 2 hours, the amount of cyclohexane adsorbed was measured at 25°C and 461 amHg.
It was 9.2 wt%.

Example-2 The external heating type reactor used in Example-1 was charged with pure water 432.59, and then potassium hydroxide 192.69. 26.99 kg of sodium hydroxide was added and maintained at 90°C.

Next, the homogeneous compound 75109 obtained in Example-1 was added and treated at 90°C for 2 hours with stirring. The amount of the homogeneous compound corresponds to 50 wt% of the total amount of the homogeneous compound used in the reaction, and the composition during treatment was slo, /Altos = 14. (
K, O+N~O)/S1~=α5+ %O/(%0-1
-N~o)=0.7°H,O/(K!O+N~o)=2
It has an oxide molar composition of 5.

During the treatment, the added homogeneous compound was dissolved in the aqueous alkali metal hydroxide mixed solution and temporarily became a solution, but was then suspended again and was in the form of a slurry upon completion of the treatment.

Subsequently, 711 g of pure water, 21a2 of potassium hydroxide, 1.19 g of sodium hydroxide, and 70 w of the total amount of homogeneous compounds.
A homogeneous compound corresponding to 1,7579 t% was added to the slurry after completion of treatment and stirred to prepare a reactant mixture.

Hereinafter, crystallization, filtration, and
A dry product was obtained by washing and drying.

As a result of X-ray diffraction, the product was found to be a highly pure L-type zeolite containing no impurities, substantially the same as in Figure 1.

Further, the adsorption amount of cyclohexane measured by the same method as in Example-1 was 9.3 wt%.

The particle size of the L-type zeolite obtained was mostly 10~
It was an aggregate of 50μ.

Example-3 The composition of an aluminum sulfate aqueous solution was (Al, 01l=5.
37w/v%, %5O4=25.76w/v%) was carried out in the same manner as in Example-1, and on a wet basis N~0=1.99wt%, Aco, os=A28v
t%, Sio, =! A homogeneous compound with a composition of 4.73 wt% i was obtained.

Next, pure water 457,
49, then potassium hydroxide 1'57.9
9. Sodium hydroxide 36. ! 1 was added and kept at 90°C.

Next, add 2.73 & 8g of the homogeneous compound and heat at 90°C for 2 hours.
Processed under stirring for hours. The amount of the homogeneous compound corresponds to 12 wt% of the total amount of the homogeneous compound used in the reaction, and the composition during treatment is Sl/A1. to=18. (K, O+N~0)/
S 1o1=[L7 s, K, O/(K, o+Na
,o)=α65r'%o/(%o+N40)
It has an oxide molar composition of =25. During the treatment, the added homogeneous compound was dissolved in the aqueous alkali metal hydroxide mixture and temporarily became a solution, but was then suspended again, and the mixture was in the form of a slurry upon completion of the treatment.

Next, pure water 1,071g, potassium hydroxide 58 &2
9. Sodium hydroxide 56.79 and total homogeneous compound amount 8
2, 73 & 8 g of homogeneous compound corresponding to 8 wt% were added into the slurry after completion of treatment and stirred to prepare a reactant mixture.

Hereinafter, crystallization, filtration, and
A dry product was obtained by washing and drying.

As a result of X-ray diffraction, the product was found to be a highly pure L-type zeolite containing no impurities, substantially the same as in Figure 1.

Further, the adsorption amount of cyclohexane measured by the same method as in Example-1 was 9.5 wt%.

The particle size of the L-type zeolite obtained was mostly 10~
It was an aggregate of 50μ.

Example-4 1.528 g of pure water was added to the external heating reactor used in Example-1,
Potassium hydroxide 521.1g, sodium hydroxide 952g
The cells were placed one after another and maintained at 90°C.

Next, the homogeneous compound 41109 obtained in Example 3 was added and treated at 90° C. for 20 hours with stirring. The amount of the homogeneous compound corresponds to the total amount of the homogeneous compound used in the reaction, and the composition during treatment is 81/A14os=18°<ybo+m~o)
/st bamboo [134, 4o/(K, 0 to 0+N) = α65
．． It has an oxide molar composition of 0/(K*O+Na,O)=32.4.

The treated slurry was directly charged into an autoclave and crystallized at 170° C. and its own pressure for 24 hours with stirring.

After the reaction was completed, the product was separated from the mother liquor by filtration, washed with water, and dried at 110°C.

As a result of X-ray diffraction, the product was found to be a highly pure L-type zeolite containing no impurities, substantially the same as in Figure 1.

Further, the adsorption amount of cyclohexane measured by the same method as in Example-1 was a9 vt%.

The particle size of the L-type zeolite obtained was mostly 1 to 1.
It was a fine aggregate of 0μ.

Example-5 In Example-1, everything was carried out in the same manner as in Example-1 except that the temperature and time at which 15 wt% of the homogeneous compound was pretreated was changed to 60° C. for 4 hours.

As a result of X-ray diffraction, the obtained product was found to be a highly pure L-type zeolite containing no impurities, substantially the same as in Figure 1.

In addition, the adsorption amount of cyclohexane measured in the same manner as in Example-1 was 9. It was Owt%.

The particle size of the obtained L-type zeolite is mostly 10~
It was an aggregate of 50μ.

Example 6 The external heating type reactor used in Example 1 was charged with 6'50 m of pure water, and then 1389° of potassium hydroxide and 52.29° of sodium hydroxide were added and maintained at 90°C.

Next, as a silica source, commercially available white carbon (Siot: = 87.7 wt%, revised ^
= 0.5wt%) 147.8g, sodium aluminate aqueous solution (AI, os = 2α05wt%,
Na! O=1159 wt%) 5z69 was added and treated at 90° C. for 2 hours with stirring. The amounts of silica and alumina added are 1 each for the silica source and alumina source used in the reaction.
It corresponds to 2wt%, and the composition at the time of treatment is 5iQz/A horse, (
b=18. (K!O+N a,o)/S 102=
0.75. KtO/(KIO+N a,o )=α6
5. It has an oxide molar composition of KO/(K, 0-1-N~o)=25. During the treatment, the added white carbon was dissolved in the aqueous alkali metal hydroxide mixed solution and temporarily became a solution, but was then suspended again, and the mixture was in the form of a slurry upon completion of the treatment.

Next, pure water 2j 549. Potassium hydroxide is 38.5%, sodium hydroxide is 25.49%, and white carbon is 1.5%, which is equivalent to 88W and 7% of the total amount of silica and alumina sources.
After the treatment was completed, 421.69 g of an aqueous sodium aluminate solution was added to the slurry and stirred to prepare a reactant mixture.

Hereinafter, crystallization, filtration, and
A dry product was obtained by washing and drying.

As a result of x11 diffraction, the product is essentially the same as in Figure 1,
It was a highly pure L-type zeolite containing no impurities.

In addition, the adsorption amount of cyclohexane measured in the same manner as in Example-1 was 9. It was Owt%.

Comparative Example-1 In Example-1, the homogeneous compound used, the alkali source, and the total amount of pure water were mixed without previously treating a part of the homogeneous compound in an alkali metal hydroxide mixed aqueous solution. A reactant mixture having the same composition as Example-1 was prepared.

Next, the reactant mixture was charged into an eau de crepe and crystallized for 20 hours under stirring at 170° C. and its autogenous pressure in the same manner as in Example-1.

Thereafter, a dry product was obtained in the same manner as in Example-1.

As a result of X-ray diffraction, the product was found to be mostly filibsite and no L-type zeolite was observed.

Comparative Example 2 In the same manner as Comparative Example 21, the entire amount of each raw material used in Example 6 was mixed to prepare a reactant mixture having the same composition as in Example 6 without any treatment step.

Thereafter, the same procedure as in Example 6 was carried out to obtain a dried product.

As a result of X-ray diffraction, the product was found to be mostly phillipsite and no L-type zeolite was observed.

Comparative Example-3 Into the external heating type reactor used in Example-1, 115 g of pure water and 51.39 g of potassium hydroxide were added. Sodium hydroxide 7 and 29 were charged in this order and maintained at 90°C.

Next, 20α8 g of the homogeneous compound obtained in Example-1 was added, and the mixture was stirred at 90° C. for 2 hours. The amount of the homogeneous compound corresponds to 8 wt% of the total amount of the homogeneous compound used in the reaction,
The composition during treatment was 5ICV/A], 0s=14°(KtO
+N~o)/s1~=[15+ %O/(K, O+N
~0)=17. It has an oxide molar composition of zo/(KyO+N~o)-25. During the treatment, the added homogeneous compound was dissolved in the aqueous alkali metal hydroxide solution to become a solution, and then suspended again, but at the completion of the treatment, it was in the form of a dilute slurry.・ Continuously, pure water 1.0289, potassium hydroxide 559,
A reactant mixture was prepared by adding 20.99% of sodium pyroacetate and a homogeneous compound of 2.309.29% corresponding to 92% of the total amount of homogeneous compounds into the slurry after the treatment was completed and stirring.

Hereinafter, everything was carried out in the same manner as in Example-1 to obtain a dry product.

As a result of X-ray diffraction of the product, it was found that a large amount of filibsite and adlaria coexisted in L-type zeolite.

Comparative Example 4 A dry product was obtained in the same manner as in Example 1 except that the temperature at which 15 wt% of the homogeneous compound was pretreated was 30°C.

As a result of X-ray diffraction of the product, it was found that a large amount of philipsite coexisted with L-type zeolite.

Comparative Example-5 All the same procedures as in Example-1 except that the temperature r+ when pre-treating 15 wt% of the homogeneous compound was 120°C.
A dry product was obtained in the same manner as in 1.

As a result of X-ray diffraction of the product, a large amount of adralia coexisted with L-type zeolite.

[Brief explanation of drawings]

FIG. 1 is a powder Xi diffraction diagram of the product obtained in Example 1 measured using the alpha doublet of copper. Patent applicant Toyo Soda Kogyo Co., Ltd. Procedure? r11 official book (Mr. Ka) May 16, 1985

Claims (1)

[Claims] 1) At least 10% by weight of the total amount of the silica source and alumina source used in the reaction when synthesizing L-type zeolite by heating and crystallizing a reactant mixture consisting of a silica source, an alumina source, and an alkali source. A stirring synthesis method for L-type zeolite, characterized in that the above is treated in advance in an aqueous alkali metal hydroxide solution in a temperature environment of 40 to 100°C. 2) Claim 1, wherein the alkali metal hydroxide aqueous solution is a mixed aqueous solution of potassium hydroxide and sodium hydroxide.
The method described in section. 3) The composition range during this treatment is SiO_2/Al_2O_3=10-20 (K_2O+Na_2O)/SiO_2=0.29-0
．． 75K_2O/(K_2O+Na_2O)=0.5~
0.9H_2O/(K_2O+Na_2O)=11~4
Claim 1 or 2 in which the oxide molar ratio is 0
The method described in section.