JP2000103613A - Synthesis of boron-containing zeolite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the yield of a crystallization product, raise the crystallinity and obtain a boron-containing zeolite in a short time by heating a mixture of a raw material for the zeolite with a boron-containing substance an organic template and water, providing a dry gel and reacting the resultant gel in a state in contact with steam under a supersaturated pressure. SOLUTION: A mixture of a raw material for zeolite (a silicon oxide) with a boron-containing substance (sodium borate, etc.), an organic template (tetrabutylammonium, etc.) and water is heated to provide a powdery dry gel, which is then brought into contact with steam under a supersaturated pressure and reacted to prepare a boron-containing zeolite. The mixing ratios of the respective raw materials are preferably within the ranges of 0.01<=A<=50.05 0.3<=B<=1.2 and 0.2<=C<=1.8 at the time of synthesizing the zeolite of the crystal form of BEA when A is the B2O3/SiO2, B is the organic template/SiO2, C is the OH/SiO2 (molar ratios).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for synthesizing a boron-containing zeolite.

[0002]

2. Description of the Related Art Zeolite is originally known as aluminosilicate, and has been used as an acid catalyst because it exhibits solid acidity under the influence of aluminum contained in its skeleton. In recent years, attempts to introduce a metal atom other than aluminum into the skeleton to have a catalytic performance other than an acid catalyst have increased (for example, an oxidation catalyst into which Ti has been introduced).

[0003] Borosilicate zeolites exhibit solid acidity as in the case of aluminosilicates. However, its acidity is considered to be quite different from that of aluminosilicate, and its application to acid catalysis that is completely different from the conventional one is expected. Boron-containing zeolites have high heat resistance (stable up to about 1000 ° C.), high hydrophobicity, and are excellent as various organic synthesis catalysts. Boron in the framework of the boron-containing zeolite can be removed under relatively mild conditions. For this reason, after removing boron from the skeleton, various metallosilicate zeolites can be synthesized by replacing with another metal species, and the boron-containing zeolite is also useful as a synthesis precursor of various metallosilicate zeolites.

[0004] Zeolite beta containing boron ([B]
-BEA) is also known as a method of using it as a raw material to lead to other zeolites, and is also a useful material in this regard. Conventionally, as a method for producing a zeolite containing boron, a hydrothermal synthesis method in which a zeolite raw material is heated together with water is known, and a zeolite crystal is obtained by this method.
For crystalline zeolite beta, see US Pat.
No. 08,069, which is identified by its X-ray diffraction pattern and discloses a method for its synthesis.
However, what is described in the above specification is not boron-containing but aluminosilicate beta ([Al] -BE).
A).

A method for synthesizing boron-containing zeolite beta (hereinafter abbreviated as [B] -BEA) is disclosed in US Pat. No. 4,788,169.
That is, a method for synthesizing [B] -BEA using tetraethylammonium cation (TEA ⁺ ) as an organic template is shown. This method contains 7000 ppm of aluminum impurities. US Patent 5,603,8
In the specification of JP-A-21, 1,1'-
Butylene range (4-aza-1-azoniabicyclo [2.
2.2] Octane) A method for synthesizing [B] -BEA using a cation is disclosed. According to this method, aluminum impurities are suppressed to 1000 ppm or less.

[0006] The classical hydrothermal synthesis method employed above employs alkali metal oxides, organic nitrogen containing cations, aluminum or boron oxides, silicon oxide sources and water. A reaction mixture of the corresponding composition is prepared and heated to high temperature in water to separate the crystalline zeolite beta crystals from the water. In the above-mentioned hydrothermal synthesis method, the volume of the reactant is large, so that the heating vessel needs to be large. Further, it takes a long time to crystallize the product. Low yield of crystallized product. Further, there is a problem that the crystallinity is low.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has an object to improve the yield of crystal products.
An object of the present invention is to provide a method capable of synthesizing a boron-containing zeolite in a short time by increasing the crystallinity.

[0008]

According to the present invention, there is provided a method for synthesizing a boron-containing zeolite, comprising the steps of: heating a mixture of a zeolite raw material, a boron-containing substance, an organic template, and water to form a powdery dry gel And a polymerization step of obtaining a boron-containing zeolite by reacting the obtained dry gel in a state of being brought into contact with water vapor having a saturated vapor pressure.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method for synthesizing a high silica zeolite containing boron in a framework structure. Instead of the hydrothermal synthesis method used for conventional zeolite synthesis,
A predetermined amount of a boron source is put into a raw material gel, and a dry gel prepared by controlling the composition of other raw materials is brought into contact with water having a saturated vapor pressure to obtain a desired crystal form of BEA or MF.
This is a method of synthesizing I, MTW zeolite crystals with high selectivity and high yield.

That is, the method for synthesizing the boron-containing zeolite of the present invention comprises the steps of: heating a mixture of a zeolite raw material, a boron-containing substance, an organic template, and water to form a powdery dry gel; And a polymerization step of obtaining a boron-containing zeolite by reacting the obtained dry gel in a state of being brought into contact with steam having a saturated vapor pressure.

The raw material of the zeolite is preferably a silicon oxide. The boron-containing substance is preferably at least one selected from sodium borate, boric acid, and boron oxide. The organic template is
It is a tetraalkylammonium ion, and is preferably at least one selected from tetrabutylammonium, tetrapropylammonium, and tetraethylammonium.

In the dry gelation step, the compounds forming the boron-containing zeolite are mixed and heated, whereby the water in the gel formed from the mixture evaporates to form a powdery dry gel. As a raw material of the zeolite, silicon oxide can be used, for example, Fumed silic
a: Cab-O-Sil M5 (manufactured by CABOT), Nipsil (manufactured by Nippon Silica Industry), Colloidal silica: Ludox HS-40, L
udox AS-40 (Du Pont), Snowtex 40
(Manufactured by Nissan Chemical Industries, Ltd.) and Aerosil (manufactured by Nippon Aerosil).

As the boron-containing substance, sodium borate, boric acid, boron oxide and the like can be used. A =
0.001 to 0.05, preferably 0.002 to 0.0
4, B = 0.1-1.5, preferably 0.3-1.2, C
= 0.1 to 1.8, preferably 0.4 to 1.3. As the organic template, tetrabutylammonium, tetrapropylammonium, or tetraethylammonium based on a compound having a spherical ion structure such as tetraalkylammonium can be used.

The ratio (molar ratio) of the mixing ratio of each of the above raw materials
A = B ₂ O ₃ / SiO ₂ , B = organic template / S
Assuming that iO ₂ and C = OH ⁻ / SiO ₂ , water / SiO ₂ = 10
-100, preferably 30-50. In the case of synthesizing a zeolite in which the boron-containing zeolite has a BEA crystal form, A = B ₂ O ₃ / SiO ₂ , B = organic template /
When SiO ₂ and C = OH ⁻ / SiO ₂ (molar ratio),
0.01 ≦ A ≦ 0.05, 0.3 ≦ B ≦ 1.2, 0.2
It is desirable to set the range of ≦ C ≦ 1.8.

The crystal form of the boron-containing zeolite is MF
When synthesizing the zeolite of I, 0.004 ≦ A ≦
It is desirable to set the range of 0.04, 0.1 ≦ B ≦ 1.5, and 0.1 ≦ C ≦ 1.5. When the crystal form of the boron-containing zeolite is to synthesize a zeolite of MTW, 0.00
1 ≦ A ≦ 0.05, 0.2 ≦ B ≦ 1.0, 0.1 ≦ C ≦
It is desirable to set the range of 1.2.

Here, the optimum value of the composition in the case of producing three kinds of BEA, MFI and MFW zeolite crystals is preferably in the following variable ranges. A = B ₂ O ₃ / SiO ₂ , B = organic template / SiO ₂ , C = OH ⁻ / SiO ₂ , X = 1
/ A, BEA: 0.02 <A <0.04 (25 <X <50) 0.8 <B <1.2 0.4 <C <1.3 MFI: 0.005 <A <0 .01 (50 <X <200) 0.3 <B <1.2 0.4 <C <1.3 MTW: 0.002 <A <0.005 (200 <X <500) 0.6 <B <1.0 0.7 <C <1.1 Here, OH is the amount of OH present in the entire system, and is the total amount of NaOH in the organic template and raw materials.

In the polymerization step, the dry gel obtained in the dry gelation step is, for example, placed in a pressurized vessel and heated and maintained in contact with steam having a saturated vapor pressure to cause a reaction.
The reaction temperature is 100-200 ° C, preferably 120-18.
By holding at 0 ° C. for 6 to 240 hours, preferably 48 to 96 hours, a crystalline zeolite is produced. The product is filtered, washed with water and dried to obtain a highly pure crystalline zeolite.

The dry gel conversion method applied to the synthesis method of the present invention is superior to the conventional hydrothermal synthesis method in the following points. That is, since the volume of the dry gel is much smaller than the corresponding hydrogel, the size of the heating vessel can be considerably reduced. The time required for crystallization is much shorter (in the conventional method, which required 10 days or more, this method can be performed in 2-3 days). Extremely good yield of crystallized product (in hydrothermal synthesis, the yield of BEA is as good as 5
It is 0 to 60%, but is 90% in the present method. ). Good crystallinity (based on whether a clear crystal form can be seen by SEM: crystals are difficult to see by hydrothermal synthesis, but can be seen by dry gel method. The zeolite of the present invention shown in FIGS. 3, 4 and 5) (See SEM photograph).

[0019]

The present invention will be described below in detail with reference to examples. Example 1 1.523 g of colloidal silica (Ludo
x AS-40, manufactured by DuPont) and 4.207 g of a 35% by weight aqueous solution of tetraethylammonium hydroxide (TEAOH) were mixed and stirred for 10 minutes. 0.07 g of 3
A 2% by weight aqueous sodium hydroxide solution was added, and an additional 30%.
Stirred for minutes. Sodium borate decahydrate 0.06
3 g was dissolved in 1.78 g of water, added to the above mixture, and stirred at room temperature for 2 hours. Thereafter, stirring was continued at 80 ° C., and when the viscosity of the gel increased, the mixture was stirred with a Teflon rod, and this was continued until the whole became a dry gel.

Next, half of the powdered dry gel was transferred to a Teflon cup (inner diameter = 20 mm, height = 20 mm), and the Teflon cup was placed in an autoclave having a capacity of 23 ml containing water (0.2 g). . The autoclave was left at 175 ° C. for 72 hours. The generated crystals were filtered, washed with water and dried to obtain a powdery boron-containing zeolite.

The powdery boron-containing zeolite was analyzed by powder XDR and confirmed to be [B] -BEA. Purity was more than 90%. As a result of elemental analysis (ICP), SiO ₂ / B ₂ O ₃ = 27 (30 in the starting gel)
Met. Table 1 shows the measurement results of the powder XDR.

[0022]

[Table 1] (Example 2) 2.253 g of colloidal silica (Ludox
(AS-40, manufactured by DuPont) and 6.311 g of a 35% by weight aqueous solution of tetraethylammonium hydroxide (TEAOH) were mixed and stirred for 10 minutes. 0.187 g of 3
A 2% by weight aqueous sodium hydroxide solution was added, and an additional 30%.
Stirred for minutes. Sodium borate decahydrate 0.01
43 g was dissolved in 2.66 g of water, added to the above mixture, and stirred at room temperature for 2 hours. Then continue stirring at 80 ° C,
When the viscosity of the gel increases, stir with a Teflon stick,
This was continued until the whole was a dry gel. As a result, a powdery dry gel was obtained.

Next, half of the powdery dry gel was transferred to a Teflon cup (inner diameter = 20 mm, height = 20 mm), and the Teflon cup was placed in an autoclave having a capacity of 23 ml containing water (0.2 g). Was. The autoclave was left at 175 ° C. for 72 hours. The generated crystals were filtered, washed with water and dried to produce a powdery boron-containing zeolite.

The obtained boron-containing zeolite was converted to powder X
Analysis by DR confirmed that it was [B] -MFI. Purity was more than 90%. As a result of elemental analysis (ICP),
This boron-containing zeolite has a SiO ₂ / B ₂ O ₃ = 94
(100 in the starting gel). Table 2 shows the powder XDR
The result of the measurement was shown.

[0025]

[Table 2] Example 3 1.502 g of colloidal silica (Ludox
AS-40, manufactured by DuPont) and 4.207 g of a 35% by weight aqueous solution of tetraethylammonium hydroxide (TEAOH) were mixed and stirred for 10 minutes. 0.07 g of 32
A weight% aqueous sodium hydroxide solution was added, and the mixture was further stirred for 30 minutes. Sodium borate decahydrate 0.063
g was dissolved in 1.78 g of water, added to the above mixture, and stirred at room temperature for 2 hours. Thereafter, stirring was continued at 80 ° C., and when the viscosity of the gel increased, the mixture was stirred with a Teflon rod, and this was continued until the whole became a dry gel. Thus, a powdery dry gel was obtained.

Next, half of the obtained powdery dry gel was transferred to a Teflon cup (inner diameter = 20 mm, height = 20 mm), and the Teflon cup was placed in an autoclave having a capacity of 23 ml containing water (0.2 g). Placed. The autoclave was left at 175 ° C. for 72 hours. The generated crystals were filtered, washed with water and dried to produce a powdery boron-containing zeolite.

The obtained boron-containing zeolite was powdered with XD
Analysis by R confirmed that it was [B] -MTW. Purity was more than 90%. As a result of elemental analysis (ICP), this boron-containing zeolite was SiO ₂ / B ₂ O ₃ = 222.
(200 in the starting gel). Table 3 shows the powder XDR.
The result of the measurement was shown.

[0028]

[Table 3] (Other Examples) As another example, a boron-containing zeolite was synthesized by the same synthesis method as in Example 1 based on the mixing ratios of the raw materials shown in Table 4 (composition ratios A, B, C, and X).
Table 4 also shows the crystal structure of the obtained boron-containing zeolite.

[0029]

[Table 4]

No. 3 in Table 4 of this embodiment. 1, No. 6, N
o. 16 and No. Powder XD of zeolite synthesized in 8
An R chart is shown in FIG. In addition, No. 1, No.
6, no. The CP-MAS-NMR spectrum chart of No. 16 is shown in FIG. 2, and photographic diagrams showing the morphological structure and crystal size of a scanning electron microscope are shown in FIGS. 3, 4, and 5.
The crystal in FIG. 3 is B-BEA, and the crystal in FIG.
−MFI, and the crystal in FIG. 5 indicates B-MTW.

As shown in FIGS. 3 to 5 above, all the zeolites show that beta zeolite crystals for the purpose of crystallinity are formed.

[0032]

According to the synthesis method of the present invention, a boron-containing zeolite is synthesized by a dry gel conversion method. In this method, the organic template exists in a spherical shape, and raw materials gather around the organic template to form a powdery dry gel that is a zeolite precursor. The dry gel is heated and reacted in water vapor having a saturated vapor pressure to form high-purity crystalline zeolite crystals in high yield.

Since the powdery raw material is reacted in steam having a saturated vapor pressure, a large amount of water is not used, so that the size of the reaction vessel can be smaller than that of the conventional method. Furthermore, compared to the method of precipitating zeolite from an aqueous solution, the method of the present invention can surely synthesize zeolite in a short time, so that the yield of the product is high and the crystallinity can be increased.

[Brief description of the drawings]

FIG. 1 is a chart of a powder XDR pattern of three types of boron-containing zeolites synthesized in this example.

FIG. 2 is a chart of ¹³ C CP-MAS-NMR spectra of three types of boron-containing zeolites synthesized in the present example.

FIG. 3 shows a boron-containing zeolite B synthesized in this example.
It is a photograph figure of a scanning electron microscope (SEM) which shows the organization form and the size of a crystal of BEA.

FIG. 4 shows a boron-containing zeolite B synthesized in this example.
It is a photograph figure of the scanning electron microscope which shows the structure form and crystal size of -MFI.

FIG. 5 shows a boron-containing zeolite B synthesized in this example.
FIG. 2 is a photograph of a scanning electron microscope showing the structure morphology and crystal size of MTW.

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[Procedure amendment]

[Submission date] December 28, 1998 (1998.12.
28)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 3

[Correction method] Change

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[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 4

[Correction method] Change

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[Procedure amendment 3]

[Document name to be amended] Drawing

[Correction target item name] Fig. 5

[Correction method] Change

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FIG. 5

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4G069 AA08 BA07A BA38 BA45A BD03A BD03B BE17B EA01Y FA01 FB08 ZA10A ZA19A ZA19B ZA32A ZA32B ZA33A ZA33B ZB03 ZB05 ZB08 ZB09 ZF07B 4G073Z17 C06 CB17 FC3 GA01 GB02 GB05 UA01

Claims (4)

[Claims] 1. A raw material for a zeolite, a boron-containing substance,
A step of heating a mixture of an organic template and water to form a dry gel in the form of a powder, and a step of polymerizing to obtain a boron-containing zeolite in which the obtained dry gel is reacted in contact with steam having a saturated vapor pressure. And a method for synthesizing a boron-containing zeolite. 2. The crystalline form of the boron-containing zeolite is BE.
The method for synthesizing a boron-containing zeolite according to claim 1, wherein when the zeolite A is synthesized, the composition of the mixture is in the following range. When A = B ₂ O ₃ / SiO ₂ , B = organic template / SiO ₂ , and C = OH ⁻ / SiO ₂ (molar ratio), 0.01 ≦ A ≦ 0.05, 0.3 ≦ B ≦ 1 .
2. The range is 0.2 ≦ C ≦ 1.8. 3. The crystal form of the boron-containing zeolite is MF.
The method for synthesizing a boron-containing zeolite according to claim 1, wherein when the zeolite I is synthesized, the composition of the mixture is in the following range. When A = B ₂ O ₃ / SiO ₂ , B = organic template / SiO ₂ , and C = OH ⁻ / SiO ₂ (molar ratio), 0.004 ≦ A ≦ 0.04, 0.1 ≦ B ≦ 1 .
5, 0.1 ≦ C ≦ 1.5. 4. The crystalline form of the boron-containing zeolite is MT.
The method for synthesizing a boron-containing zeolite according to claim 1, wherein when the zeolite W is synthesized, the composition of the mixture is in the following range. When A = B ₂ O ₃ / SiO ₂ , B = organic template / SiO ₂ , and C = OH ⁻ / SiO ₂ (molar ratio), 0.001 ≦ A ≦ 0.05, 0.2 ≦ B ≦ 1 .
0, 0.1 ≦ C ≦ 1.2.