JP2000185912A - Crystalline titanosilicate zeolite and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly pure titanosilicate zeolite which does not contain A1 atom in the skeleton and can easily be produced by a new method that a dried powdery reaction mixture is heated and brought into contact with only steam to crystallize the zeolite. SOLUTION: This crystalline titanosilicate zeolite is obtained by a production method comprising the following processes: (a) a process for preparing a mixture of an organic amine compound with an alkali metal hydroxide aqueous solution, (b) a process for adding a mixture of a silica source with water to the mixture, and homogenizing the mixture with stirring, (c) a process for adding an aqueous mixture solution of a titania source with hydrogen peroxide to the mixture, and homogenizing the mixture with stirring, (d) a process for stirring and aging the mixture at a temperature of 10-40 deg.C for >=1 hr, (e) a process for stirring and drying the aged reaction mixture at a temperature of >=50 deg.C, (f) a process for pulverizing the dried reaction mixture, and then (g) a process for bringing the dried powdery reaction mixture into contact with only the self-generated steam at a temp. of 120-200 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a crystalline titanosilicate zeolite useful as a catalyst or an adsorbent and characterized by a production method. In particular, the present invention provides a crystalline titanosilicate zeolite having excellent properties as an oxidation catalyst for organic compounds.

[0002]

2. Description of the Related Art BEA-type zeolites are disclosed in US Pat.
This is an aluminosilicate zeolite having 12-membered ring pores disclosed for the first time in JP-A-8,069. In the synthesis methods proposed so far, an aqueous reaction slurry using tetraethylammonium ion as a template agent was used as a raw material. That is, in a typical example, H
An aqueous slurry having a ₂ O / SiO ₂ ratio of 20 and capable of uniform stirring and mixing is used.

When the ratio of H ₂ O / SiO ₂ is less than 10, uniform mixing becomes impossible.

Accordingly, in the prior art, a BEA-type zeolite was crystallized by preparing a homogeneously mixed slurry of raw material components and heating the slurry. However,
In the above-mentioned conventional method, since a part of the raw material components are dissolved in water at the time of heating, the ratio of the components converted into crystals is inevitably reduced, and the alkali component is diluted by a large amount of water, so that the crystallization time is long. Become. In addition, since the aqueous slurry is heated, it has a drawback that a closed container having a relatively large capacity is required for the weight of the generated crystals.

The same applies to the synthesis of MFI type and MEL type.

[0006] Titanosilicate zeolite is a kind of zeolite similar to these aluminosilicate zeolites, but differs from ordinary aluminosilicate zeolites in that the skeleton atoms are composed of only Si, Ti and oxygen atoms. Since it was discovered that introducing a Ti atom into the skeleton effectively acts as an oxidation catalyst for organic compounds, many attempts have been made to synthesize titanosilicate zeolites. Although those containing can be synthesized relatively easily, there are few synthesis examples of pure titanosilicate zeolites containing no Al atom.

[0007] For example, in the case of BEA-type titanosilicate zeolite, Progressin Zeolite
and Microporous Material
s (Studies in Surface Scie
nce and Catalysis, Vol. 10
5), p. Although the titanosilicate zeolite containing no Al atom can be synthesized by the method described in 1093-1100, 1997, it is necessary to use very expensive amine and dibenzyldimethylammonium ion.

[0008] Applied Catalyst
s A, General, Vol. 167, p. 331
-342, 1998 also requires the use of special and expensive dicyclohexylmethyl-dimethylammonium hydroxide. In addition, Chem. Co
mmun. , 2367, 1996 is a hydrothermal synthesis that requires the addition of toxic hydrogen fluoride. Further, it is said that crystals formed by these methods are easily accompanied by an amorphous substance, and the crystals have many defects.

In addition, in the hydrothermal synthesis of MFI-type titanosilicate zeolite, Applied Catal
ysis, A, Vol. 92, p. 93, 1993 and Studies in Surface Science
ce and Catalysis, Vol. 69,
p. 79, 1991, it is necessary to use a template agent having as little alkali content as possible.

[0010] All of these methods have the same disadvantages as the above-mentioned aluminosilicate zeolite synthesis method using an aqueous reaction slurry.

The MEL titanosilicate zeolite is also A
Applied Catalysis, Vol. 58,
p. 21, 1990; Catalysis, Vo
l. 130, p. 440, 1991, etc., but a method of heating an aqueous slurry containing tetrabutylammonium ions does not produce pure crystals.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method in which Al atoms are incorporated into a skeleton which can be easily produced by a new method of crystallizing zeolite by contacting and heating a dried powdery reaction mixture with only steam. The present invention provides a high-purity titanosilicate zeolite containing no zeolite.

Further, by adopting a method of increasing the efficiency of the reaction by reducing the volume of the raw material composition and simultaneously increasing the yield of the raw material components, it can be easily obtained without using additives such as hydrogen fluoride. An object of the present invention is to propose a high-purity titanosilicate zeolite that can be produced by crystallization in a relatively short time using a possible organic amine compound.

[0014]

SUMMARY OF THE INVENTION The present invention reduces the volume of a raw material composition by contacting a powdery reaction mixture having a low water content only with steam that grows naturally at 120 to 200 ° C. The present invention relates to a high-purity titanosilicate zeolite obtained by a method for increasing the reaction efficiency by increasing the ratio of a raw material composition in a reaction vessel.
It is also a high-purity titanosilicate zeolite obtained by a method of reducing the water content at the same time to reduce the raw material components soluble in water at the time of heating and improving the yield.

Hereinafter, the present invention will be described in detail.

The powdery reaction mixture of the present invention comprises a silica source,
It is composed of a titania source, an alkali source and an organic amine compound, and does not need to contain a large amount of water. As the silica source, fumed silica or alkoxysilane containing almost no aluminum as an impurity is used. Alkoxy titanium is preferably used as the titania source. These alkoxides preferably have the same alkyl group as the template agent described below, but tetrabutoxytitanium is most preferably used. As the alkali source, an alkali metal hydroxide such as sodium hydroxide, potassium hydroxide, lithium hydroxide or the like is used.

In the present invention, unlike the above-described method using a hydrothermal reaction slurry, a novel titanosilicate having good crystallinity can be obtained by adding an appropriate amount without inhibiting the crystallization of the alkali source. It can be said that it is a titanosilicate zeolite obtained by the method.

As the organic amine compound, a compound containing a tetraethylammonium ion for BEA type titanosilicate zeolite, a compound containing tetrapropylammonium ion for MFI type titanosilicate zeolite, and a MEL type titanosilicate zeolite In the case of zeolite, a compound containing a tetrabutylammonium ion is used. These alkyl ammonium compounds may be hydroxides or halides as long as they contain an appropriate alkyl ammonium ion. As the hydrogen peroxide used for stabilizing the alkoxytitanium, a 30% aqueous solution is usually used. These raw materials are mixed and crystallized through the following steps.

A) preparing a mixture of an organic amine compound and an aqueous solution of an alkali metal hydroxide; b) adding a silica source and water to the mixture to stir and homogenize; c) adding a titania source and a peroxide to the mixture; A mixed aqueous solution of hydrogen is added to stir and homogenize. D) These mixtures are aged by stirring at a temperature in the range of 10 to 40 ° C for 1 hour or more. E) The aged reaction mixture is stirred and dried at a temperature of 50 ° C or more. F) pulverizing the dried reaction mixture; g) contacting the dried powdered reaction mixture only with steam which grows at 120-200 ° C.

When these reaction mixtures are sufficiently mixed in the presence of water to form a uniform slurry, the amount of water is not particularly limited. Next, the temperature at which the homogeneous slurry is stirred and homogenized after aging is important, and if it exceeds 40 ° C., crystallization does not proceed. When the temperature is lower than 10 ° C., no crystallization or only a low crystallinity is obtained.

Next, the aged reaction mixture is uniformly dried at a temperature of 50 ° C. or higher until an equilibrium water content is reached. When the drying temperature is lower than 50 ° C., the water content of the powdery raw material composition becomes high, and the raw material components are eluted during crystallization to lower the yield.

On the other hand, if the drying temperature is too high, crystallization hardly proceeds. In the drying method, it is necessary to dry the aqueous slurry of the raw material mixture under stirring. When dried without stirring, the composition of the powdery reaction mixture becomes non-uniform, and impurities are easily produced as by-products or the crystallinity tends to be low. The chemical composition of the obtained powdery reaction mixture is represented by the molar ratio of the oxide in the anhydrous state and is adjusted to the following range.

In the case of BEA type titanosilicate zeolite, SiO ₂ / TiO ₂ ≧ 20 M ₂ O / SiO ₂ = 0.04-0.2 R ₂ O / SiO ₂ = 0.1-0.3, M is an alkali metal, and R is a tetraethylammonium ion of an organic amine compound.

In the case of the MFI type titanosilicate zeolite, SiO ₂ / TiO ₂ ≧ 50 M ₂ O / SiO ₂ = 0.04-0.2 R ₂ O / SiO ₂ = 0.1-0.3, M is an alkali metal, and R is a tetrapropyl ammonium ion of an organic amine compound.

In the case of the MEL titanosilicate zeolite, SiO ₂ / TiO ₂ ≧ 50 Na ₂ O / SiO ₂ = 0.04-0.2 R ₂ O / SiO ₂ = 0.1-0.3, M is an alkali metal, and R is a tetrabutylammonium ion of an organic amine compound.

The powdery reaction mixture thus prepared is placed in a closed vessel, and is crystallized without direct contact with water, but only with steam generated at the reaction temperature.
The crystallization temperature is in the range of 120-200 ° C. 12
At a temperature of 0 ° C. or less, the crystallization rate is extremely slow, and the economic rationality is lacking. At a temperature of 200 ° C. or higher, the decomposition of the organic amine compound becomes severe, and it is difficult to obtain a zeolite having a high crystallinity. The method and apparatus for heating the powdery reaction mixture by contacting it only with steam are not particularly limited.

Although the apparatus used in the examples is shown in FIG. 1, the embodiment is not limited to this. A closed container in which the powdery reaction mixture is put in a container and water is put outside the container may be used. Alternatively, a method in which the powdery raw material composition is continuously moved while being in contact with steam may be used.

In order to use the titanosilicate zeolite effectively as an oxidation catalyst or the like, it is necessary to reliably introduce Ti atoms into the framework. Therefore, it is important to confirm that a Ti atom exists in the skeleton. When a Ti atom is introduced into the zeolite skeleton, an absorption specific to tetracoordinate Ti appears at about 210 nm in an ultraviolet-visible absorption spectrum. In the infrared absorption spectrum, 960
An absorption peak due to a Ti—O—Si bond is observed near cm ⁻¹ . These measurements make it possible to confirm whether or not Ti atoms are present in the skeleton.

[0029]

According to the method of the present invention, titanosilicate zeolite containing no Al atom as an impurity can be easily crystallized, and not only can Ti atoms be reliably introduced into the framework, but also a powdery reaction mixture can be obtained. By using, the volume of the raw material composition can be reduced, so that the reaction efficiency per volume can be increased. Further, since the raw material components do not dissolve in water and are mostly transformed into crystals, the reaction yield can be increased. Therefore, if a method in which the powdery reaction mixture is continuously moved while being brought into contact with water vapor is employed, continuous synthesis of zeolite is possible. Further, since almost no waste liquid is generated, there is no need to collect and treat the waste liquid, which is economical.

[0030]

The present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the present invention.

Example 1 The raw materials used in this example were all adjusted to a temperature of 20 ° C. in advance. 1.0 ml of an aqueous sodium hydroxide solution (concentration: 4 mol / l) and 6.7 g of an aqueous solution of tetraethylammonium hydroxide (concentration: 30%) were mixed. Thereafter, a slurry in which 1.5 g of fumed silica was uniformly dispersed in 15 ml of water was added to the mixed aqueous solution. Next, 1.0 ml of water and 1.0 ml of hydrogen peroxide solution (concentration 30
%) And 0.17 g of a mixed aqueous solution of tetrabutoxytitanium, and aged at 20 ° C. for 2 hours with vigorous stirring.

The aqueous mixture was then stirred at 80 ° C.
To obtain a dry mixture.
Next, this dried mixture was pulverized in a mortar to obtain a powdery reaction mixture. The chemical composition of this powdery reaction mixture was as follows on an anhydrous basis.

[0033] _{4.8Na 2 O · TiO 2 · 50SiO} 2 ·
9.25 TEA ₂ O This was placed on a support plate in the closed container shown in FIG. 1, water was added to the bottom of the container, and the container was heated at 140 ° C. for 8 days. The product was briefly washed with water and dried at 80 ° C. As a result of the X-ray diffraction measurement, the product was a BEA zeolite as shown in FIG. The chemical composition of components that do not contain organic matter and moisture is 0.1%.
22Na was _{2 O · TiO 2 · 65SiO 2} . Also,
As a result of ultraviolet-visible absorption spectrum measurement, a clear absorption was observed at around 210 nm.

[0034] Using the same raw material as in Example 1, the aqueous mixture was prepared in a similar manner, this stirring dried, and triturated with a temperature of _{80 ℃, 4.8Na 2 O · TiO} 2 in anhydrous basis · 50SiO was obtained ₂ · 11TEA powdery reaction mixture having a composition of ₂ O. This was heated at 140 ° C. for 8 days in the same manner as in Example 1.

The product was briefly washed with water and dried at 80.degree. The X-ray diffraction pattern was essentially the same as FIG. The chemical composition of the components that do not contain organic matter and water was _{0.23Na 2 O · TiO 2 · 63SiO} 2. Also, as a result of UV-visible absorption spectrum measurement,
Clear absorption was observed near 210 nm.

Example 3 An aqueous mixture was prepared in the same manner using the same raw materials as in Example 1, and this was stirred and dried at a temperature of 80 ° C., pulverized, and converted to anhydrous 4.8 Na ₂ O.TiO _2.・ 50SiO ₂・ 12.5TEA
A powdery reaction mixture having a composition of ₂ O was obtained. This was heated at 140 ° C. for 8 days in the same manner as in Example 1.

The product was briefly washed with water and dried at 80.degree. The X-ray diffraction pattern was essentially the same as FIG. The chemical composition of the components that do not contain organic matter and water was _{0.23Na 2 O · TiO 2 · 63SiO} 2. Also, as a result of UV-visible absorption spectrum measurement,
Clear absorption was observed near 210 nm.

Example 4 The same powdery reaction mixture as in Example 1 was heated in the same manner as in Example 1 at 140 ° C. for 2 days and then at 180 ° C. for 1 day. The product was briefly washed with water and dried at 80 ° C.

The X-ray diffraction pattern was essentially the same as FIG. In addition, as a result of measurement of the ultraviolet-visible absorption spectrum, 21
Clear absorption was observed near 0 nm.

Example 5 The raw materials used in this example were all adjusted to a temperature of 20 ° C. in advance. 1.0 ml of sodium hydroxide aqueous solution (concentration 4
Mol / liter) and 20.3 g of an aqueous solution of tetrapropylammonium hydroxide (concentration: 10%).
Thereafter, a slurry in which 1.5 g of fumed silica was uniformly dispersed in 15 ml of water was added to the mixed aqueous solution.
Next, a mixed aqueous solution of 1.0 ml of water, 1.0 ml of a hydrogen peroxide solution (concentration: 30%) and a mixed aqueous solution of 0.17 g of tetrabutoxytitanium was added, and the mixture was stirred at 20 ° C.
Aged for hours. The aqueous mixture is then stirred for 80
The mixture was dried by heating at 0 ° C until the water content reached an equilibrium amount to obtain a dry mixture.

Next, the dried mixture was pulverized in a mortar to obtain a powdery reaction mixture. The chemical composition of this powdery reaction mixture was as follows on an anhydrous basis.

[0042] _{5Na 2 O · TiO 2 · 50SiO} 2 · 10TPA 2 O it was placed on the support plate in the closed container shown in FIG. 1, filled with water in the bottom of the vessel and heated for 3 days at 180 ° C.. The product was briefly washed with water and dried at 80 ° C. As a result of the X-ray diffraction measurement, the product was an MFI-type zeolite as shown in FIG. The chemical composition of the components that do not contain organic matter and water was _{0.59Na 2 O · TiO 2 · 90SiO} 2. Also, as a result of UV-visible absorption spectrum measurement,
Clear absorption was observed near 210 nm.

Example 6 All the raw materials used in this example were previously adjusted to a temperature of 20 ° C. 1.0 ml of sodium hydroxide aqueous solution (concentration 4
Mol / l) and 24 ml of an aqueous tetrabutylammonium hydroxide solution (concentration: 4 mol / l). Thereafter, a slurry in which 1.5 g of fumed silica was uniformly dispersed in 15 ml of water was added to the mixed aqueous solution. Next, a mixed aqueous solution of 1.0 ml of water, 1.0 ml of a hydrogen peroxide solution (concentration: 30%) and a mixed aqueous solution of 0.17 g of tetrabutoxytitanium was added, and the mixture was stirred vigorously.
Aged at 0 ° C. for 2 hours. Next, this aqueous mixture was heated and dried at 80 ° C. with stirring until the water content reached an equilibrium amount to obtain a dry mixture. Next, the dried mixture is crushed in a mortar,
A powdery reaction mixture was obtained.

The chemical composition of this powdery reaction mixture was as follows on an anhydrous basis.

[0045] _{5Na 2 O · TiO 2 · 50SiO} 2 · 10TBA 2 O it was placed on the support plate in the closed container shown in FIG. 1, filled with water in the bottom of the vessel and heated for 3 days at 180 ° C.. The product was briefly washed with water and dried at 80 ° C. As a result of X-ray diffraction measurement, the product was identified as a MEL zeolite. The chemical composition of the components that do not contain organic matter and water was _{0.61Na 2 O · TiO 2 · 88SiO} 2. Also, as a result of UV-visible absorption spectrum measurement,
Clear absorption was observed near 210 nm.

Comparative Example 1 The same aqueous mixture prepared in Example 2 was mixed at 4 ° C. with 2
After aging with stirring for a period of time, the mixture was dried and pulverized at 80 ° C to obtain a powdery reaction mixture. This was converted to 140 in the same manner as in Example 1.
Heated at ° C. for 8 days. The product was briefly washed with water and dried at 80 ° C. From the X-ray diffraction pattern, the product was almost amorphous.

Comparative Example 2 The same aqueous mixture prepared in Example 2 was aged by stirring at 50 ° C. for 2 hours, then dried and pulverized at 80 ° C. to obtain a powdery reaction mixture. This is converted to 14 in the same manner as in Example 1.
Heated at 0 ° C. for 8 days. After washing the product with water,
And dried. From the X-ray diffraction pattern, the product was amorphous.

Comparative Example 3 The same aqueous mixture prepared in Example 2 was stirred and aged at 20 ° C. for 2 hours, then dried and pulverized at 60 ° C. to obtain a powdery reaction mixture. This is converted to 14 in the same manner as in Example 1.
Heated at 0 ° C. for 8 days. After washing the product with water,
And dried. From the X-ray diffraction pattern, the product was almost amorphous.

Comparative Example 4 The same powdery reaction mixture as prepared in Example 2 was used.
Example 2 except no water at the bottom of the autoclave
Crystallization was carried out under exactly the same conditions. After briefly washing the product with water,
Dried at 80 ° C. From the X-ray diffraction pattern, the product was amorphous.

[0050] was obtained in Comparative Example 5 powdered reaction mixture Example 5 the same method with the composition _{TiO 2 · 50SiO 2 · 10TPA 2} O below in anhydrous basis except for not using an aqueous solution of sodium hydroxide. This was crystallized under the same conditions as in Example 5. The product was briefly washed with water and dried at 80 ° C. From the X-ray diffraction pattern, the product was amorphous.

Comparative Example 6 A powdery reaction mixture having the following composition TiO ₂ · 50 SiO ₂ · 10TBA ₂ O was obtained in the same manner as in Example 6 except that an aqueous sodium hydroxide solution was not used. This was crystallized under the same conditions as in Example 6. The product was briefly washed with water and dried at 80 ° C. From the X-ray diffraction pattern, the product was amorphous.

[Brief description of the drawings]

FIG. 1 is a closed container used in the present invention.

[Explanation of symbols]

 (A) sealed container (b) thermocouple (c) Teflon container (d) support plate (e) powdery reaction mixture (f) water

FIG. 2 is a CuKα X-ray diffraction diagram of the titanosilicate zeolite obtained in Example 1.

FIG. 3 is a CuKα X-ray diffraction diagram of the titanosilicate zeolite obtained in Example 5.

Claims (5)

[Claims] 1. A crystalline titanosilicate zeolite obtained by a production method comprising the following steps. a) preparing a mixture of an organic amine compound and an aqueous solution of an alkali metal hydroxide; b) adding a mixture of a silica source and water to the mixture to stir and homogenize; c) adding a titania source and a peroxide to the mixture. A mixed aqueous solution of hydrogen is added to stir and homogenize. D) These mixtures are aged by stirring at a temperature in the range of 10 to 40 ° C for 1 hour or more. E) The aged reaction mixture is stirred and dried at a temperature of 50 ° C or more. F) pulverizing the dried reaction mixture; g) contacting the dried powdered reaction mixture only with steam which grows at 120-200 ° C. 2. The crystalline titanosilicate zeolite according to claim 1, wherein the crystalline form is BEA type, MFI type and MEL.
A crystalline titanosilicate zeolite characterized in that the crystalline titanosilicate zeolite is any one of the types. 3. A crystalline titanosilicate zeolite according to claim 1, SiO ₂ chemical composition of the reaction mixture of an organic amine compound and an alkali metal hydroxide aqueous solution is expressed in terms of mole ratios of oxides in the anhydrous state / TiO ₂ ≧ 20 M ₂ O / SiO ₂ = 0.04-0.2 R ₂ O / SiO ₂ = 0.1-0.3, M is an alkali metal, and R is a tetraethylammonium ion of an organic amine compound And the crystal form is BEA
A titanosilicate zeolite characterized by being a type. 4. The crystalline titanosilicate zeolite according to claim 1, wherein the chemical composition of the reaction mixture of the organic amine compound and the aqueous alkali metal hydroxide solution is represented by the molar ratio of SiO ₂ in the anhydrous state. / TiO ₂ ≧ 50 M ₂ O / SiO ₂ = 0.04-0.2 R ₂ O / SiO ₂ = 0.1-0.3, M is an alkali metal, and R is an organic amine compound tetrapropylammonium It is an ion and the crystal form is MF
A titanosilicate zeolite, which is of type I. 5. A crystalline titanosilicate zeolite according to claim 1, SiO ₂ chemical composition of the reaction mixture of an organic amine compound and an alkali metal hydroxide aqueous solution is expressed in terms of mole ratios of oxides in the anhydrous state / TiO ₂ ≧ 50 M ₂ O / SiO ₂ = 0.04-0.2 R ₂ O / SiO ₂ = 0.1-0.3, M is an alkali metal, and R is an organic amine compound tetrabutylammonium It is an ion and the crystal type is MEL
A titanosilicate zeolite characterized by being a type.