JP2000211914A - New zeolite and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To synthesize an NU-1 type zeolite substantially free from Al and an alkali metal in good yield by hear-treating a dry gel containing a silicon raw material without substantially containing the alkali metal and Al and a mold agent in a steam atmosphere. SOLUTION: An aqueous solution of a mold agent such as a tetraalkylammonium hydroxide is mixed and stirred with a silica source to provide a uniform sol, which is then heated, evaporated to dryness and dried while being stirred. Thereby, a dry gel is obtained and pulverized to afford a fine powder, which is placed in a container such as a beaker and installed in a heat-resistant container such as an autoclave containing water placed in the lower part. The heat-resistant container is heated to hear-treat the dry gel preferably at >=150 deg.C in a produced steam atmosphere. When titanium is contained in the sol, the titanium such as titanium peroxide is added when preparing the sol. The atomic ratio of Si/Ti in the dry gel is preferably >=10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a NU-1 type zeolite. The NU-1 type zeolite is
It is considered to be useful as a catalyst having activity in various reactions such as an isomerization reaction, an oxidation reaction, and a transesterification reaction, and as an adsorbent for various substances. Among them, NU-1 type zeolite containing titanium is considered to be effective as a catalyst for an oxidation reaction or a transesterification reaction, and is a substance considered to be useful in the chemical industry.

[0002]

2. Description of the Related Art NU-1 type zeolite is a zeolite which was discovered in 1977 as an aluminosilicate having small pores having a six-membered oxygen ring. Although the topology of the crystal has not been completely determined, its structure can be identified by powder X-ray diffraction. According to U.S. Pat. No. 4,060,590 (1977), NU-1 type zeolite is useful as a catalyst having an activity in reactions such as xylene isomerization and an adsorbent for various substances. ing.

[0003] As a synthetic method of a conventional NU-1 zeolite, aluminum and alkali metal element, and in particular reported synthesis example of the condition in the presence of sodium, the resulting NU-1 zeolite SiO ₂ / Al ₂ O ₃ ratio is 1
5 to 180 (Zeolites 18 36
1 page (1997)). NU-1 containing titanium
Similarly, for a zeolite, a synthesis method under the condition that aluminum or an alkali metal element is present or a synthesis method using a seed crystal containing aluminum has been reported.

As described above, the conventional NU-1 type zeolite only discloses a NU-1 type zeolite substantially containing an alkali metal element such as aluminum and sodium, and a synthesis method thereof. N containing titanium
In the case of U-1 type zeolite, since the synthesis under conditions in which the aluminum and alkali metal element present, since the titanium will be precipitated as TiO ₂ initially, NU-1
There is a problem that titanium is not sufficiently dispersed in the zeolite.

[0005] However, it is difficult to synthesize NU-1 type zeolite under the condition that no aluminum or alkali metal element is present in the prior art. Furthermore, in the case of a NU-1 type zeolite containing titanium, it is necessary to synthesize under conditions in which aluminum or an alkali metal element does not exist in order to highly disperse titanium. It was difficult with conventional techniques to synthesize under conditions that did not.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is an NU-1 type zeolite comprising silicon as a metal element, wherein the zeolite is an alkali metal element and aluminum. It is an object of the present invention to provide a NU-1 type zeolite containing no, and an inexpensive and industrially advantageous method for producing the NU-1 type zeolite.

Another invention of the present invention relates to a NU-1 type zeolite comprising silicon and titanium as metal elements, wherein the zeolite does not contain an alkali metal element and aluminum and a NU-1 type zeolite.
It is an object of the present invention to provide an inexpensive and industrially advantageous production method of a type zeolite.

[0008]

Means for Solving the Problems The present inventors have proposed a NU-1 type zeolite composed of silicon as a metal element or a NU-1 type zeolite composed of silicon and titanium as a metal element, wherein the zeolite is an alkali metal element. As a result of intensive studies on a method of synthesizing a NU-1 type zeolite containing no aluminum and aluminum, a dry gel containing silicon and a mold, or a dry gel containing silicon, titanium and a mold was prepared under a steam atmosphere. Heat treatment (hereinafter sometimes referred to as dry gel conversion)
As a result, a method for producing a NU-1 type zeolite substantially containing no aluminum or alkali metal element was found, and the present invention was completed.

That is, the present invention relates to a NU-1 type zeolite comprising silicon as a metal element, wherein the zeolite does not contain an alkali metal element and aluminum (hereinafter referred to as NU-1 type zeolite).
(Sometimes referred to as type zeolite (I)).

Another aspect of the present invention is a NU-1 type zeolite comprising silicon and titanium as a metal element, wherein the zeolite does not contain an alkali metal element and aluminum. (Hereinafter sometimes referred to as NU-1 type zeolite (II)).

Another invention of the present invention is characterized in that a dry gel containing a silicon material substantially free of an alkali metal element and aluminum and a mold agent is heat-treated in a steam atmosphere. Type 1 zeolite (I)
And a method for producing the same.

Another invention of the present invention is characterized in that a dry gel containing a silicon raw material substantially free of an alkali metal element and aluminum, titanium and a mold agent is heat-treated in a steam atmosphere. The present invention relates to a method for producing type-1 zeolite (II).

Preferably, the titanium source is a titanium peroxide.

[0014] The molding agent is preferably a tetraalkylammonium hydroxide, more preferably tetramethylammonium hydroxide.

The heat treatment temperature in the steam atmosphere is 15
The temperature is preferably 0 ° C. or higher.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The NU-1 type zeolite (I) of the present invention is a NU-1 type zeolite comprising silicon as a metal element, wherein the zeolite does not contain an alkali metal element and aluminum. I do.

As a method for producing the NU-1 type zeolite (I), for example, a method of heat-treating a dry gel containing a silicon raw material substantially free of an alkali metal element and aluminum and a molding agent in a steam atmosphere. Is obtained.

NU-1 type zeolite (II) of the present invention
Is a NU- consisting of silicon and titanium as metal elements
Type 1 zeolite, wherein the zeolite does not contain an alkali metal element and aluminum.

As a method for producing the NU-1 type zeolite (II), for example, a dry gel containing a silicon raw material substantially free of an alkali metal element and aluminum, titanium and a molding agent is heat-treated in a steam atmosphere. Is obtained in the following manner.

As the silicon raw material used in the production of the NU-1 type zeolite of the present invention, various silicon raw materials can be used as long as they are substantially free of alkali metal elements and aluminum. , Colloidal silicon, fumed silicon, aerosil silicon and the like are preferably used.

Various titanium sources can be used as a titanium raw material for producing the NU-1 type zeolite of the present invention, but orthotitanate esters, particularly butyl orthotitanate, are preferred in terms of handling. The titanium source is preferably used as a peroxide. The peroxide can be obtained by treating the above-mentioned orthotitanate with a peroxide such as hydrogen peroxide.

The molding agent used for producing the NU-1 type zeolite of the present invention is not particularly limited, but a tetraalkylammonium hydroxide is preferable, and as the alkyl group, various quaternary amines of an alkyl group can be used. However, amines such as a methyl group, an ethyl group, and a propyl group are preferably used because of industrial availability. Among them, tetramethylammonium hydroxide is preferred.

The specific method for preparing the NU-1 type zeolite of the present invention is not particularly limited. 1. Step of preparing dry gel containing mold agent, silica, and optionally titanium 2. a crystallization step of heat-treating the dried gel in a steam atmosphere; It is preferable to carry out the firing step in order to remove the template contained in the zeolite after crystallization. Further, each of the above steps will be described in detail below.

1. Preparation Step of Dry Gel An aqueous solution of a template (preferably tetraalkylammonium hydroxide) and a silica source (orthosilicate, colloidal silicon, fumed silicon, aerosil silicon, etc.) are mixed and stirred to form a uniform sol. The sol is heated, evaporated to dryness with stirring, and then dried to obtain a dried gel.

When titanium is contained, a titanium source (preferably titanium peroxide) is added during the preparation of the sol. Titanium peroxide is obtained by treating a titanate or the like with a peroxide such as hydrogen peroxide.

In the preparation of the NU-1 type zeolite (II) of the present invention, the Si / Ti atomic ratio in the dry gel charged is 1
It is preferably 0 or more, more preferably 20 or more.

2. Crystallization Step The obtained dried gel is pulverized into a differential powder, placed in a container such as a PTFE beaker, and placed in a pressure-resistant container such as an autoclave filled with water below. The pressure vessel is heated, and heat treatment is performed in a generated steam atmosphere.

The heat treatment temperature in a steam atmosphere during the synthesis of the NU-1 type zeolite of the present invention must be somewhat high, preferably 150 ° C., more preferably 170 ° C.
That is all. The processing time is in the range of several hours to several days, but a certain long processing time is required for sufficient crystallization.

3. Firing step The obtained zeolite contains a mold agent as it is,
As it is, it cannot be used as a catalyst or adsorbent. In order to remove this mold agent, it is usually fired in an oxygen-containing gas atmosphere (an air atmosphere if there is no problem). The firing temperature is 400 ° C. or more, preferably 500 ° C. or more, and the firing time is several hours to about 1 day, depending on the temperature.

The identification of NU-1 type zeolite is carried out, for example, by
The powder X-ray diffraction spectrum of the obtained zeolite was measured according to the literature (Zeolites, Vol. 18, p. 361 (1997)).
) Can be confirmed by comparison with the powder X-ray diffraction spectrum (see FIG. 2).

The fact that zeolite does not contain aluminum and alkali metal elements can be confirmed by a commonly used metal analysis method. For example, aluminum is determined by ICP emission analysis using alkali metal. The element can be easily confirmed by not being detected by atomic absorption spectrometry.

The NU-1 type zeolites (I) and (II) of the present invention are useful as catalysts having activity in various reactions such as isomerization reaction, oxidation reaction and transesterification reaction, and as adsorbents for various substances. And in particular, N containing titanium
U-1 type zeolite (II) can be suitably used as a catalyst effective for an oxidation reaction using a peroxide such as hydrogen peroxide as an oxidizing agent, a transesterification reaction and the like.

[0033]

EXAMPLES Example 1 25% by weight of tetramethylammonium hydroxide (TMA
-OH) aqueous solution with 18.2 g of fumed silica (trade name:
6. Add 6.0 g of Aerosil 200) and stir for 1 hour. After a uniform sol, raise the temperature to 80 ° C,
Dry for 8 hours with stirring.

The dried gel is crushed into a powder. This powder gel was put in a PTFE beaker, and synthesized in an autoclave filled with 10 g of water at 170 ° C. for 5 days. The obtained powder was calcined at 550 ° C. for 12 hours under flowing air to obtain zeolite (A).

In the obtained zeolite (A), no Al was detected by ICP emission spectrometry, and no alkali metal element was detected by atomic absorption spectrometry. Therefore, the zeolite (A) is a zeolite made of silica containing no Al or an alkali metal element.

From the electron microscope (FEM-SEM) photograph of the obtained zeolite (A), it can be seen that fine needle-like crystals are formed, which indicates that the external surface area is large. Fig. 1 shows the powder X-ray diffraction spectrum of zeolite (A).
Shown in The literature (Zeolites 18 361)
The powder X-ray diffraction spectrum shown on page (1997) is shown in FIG. The overall pattern is in good agreement. Also, from the relationship between 2θ and the intensity, the appearance position of the approximate peak matches the intensity. Therefore, from FIGS. 1 and 2, it was found that the crystal structure of the zeolite (A) obtained in Example 1 was a NU-1 type zeolite.

The zeolite (A) obtained in Example 1
Is shown in FIG. 5 (lower diagram, spectrum b).

Example 2 1.15 g of butyl orthotitanate is added to 5.0 g of pure water with stirring. 1. After 10 minutes, 25% by weight aqueous hydrogen peroxide
Then, the mixture was stirred at room temperature for 30 minutes to obtain an aqueous titanium peroxide solution.

18.2 g of a 25% by weight aqueous solution of tetramethylammonium hydroxide (TMA-OH) was added with stirring, and finally fumed silica (trade name: Aerosil 20)
0) Add 6.0 g and stir for 1 hour. After forming a uniform sol, the temperature is increased to 80 ° C. and dried for 8 hours with stirring.

The dried gel is crushed into a powder. This powder gel was put in a PTFE beaker, and synthesized in an autoclave filled with 10 g of water at 170 ° C. for 6 days. The obtained powder was calcined at 550 ° C. for 12 hours under flowing air to obtain a Ti-containing zeolite (B).

In the obtained zeolite (B), Al was not detected by ICP emission spectrometry, and no alkali metal element was detected by atomic absorption spectrometry. Therefore, the zeolite (B) is a zeolite containing Ti that does not contain Al or an alkali metal element.

From an electron microscope (FEM-SEM) photograph of the obtained zeolite (B), it can be seen that fine needle-like crystals have been formed, indicating that the external surface area is large. The zeolite (B) has an Si / Ti atomic ratio of 36, and a specific surface area by nitrogen adsorption (indicating the area outside the crystal) of 132.
m ² / g.

FIG. 3 shows the powder X-ray diffraction spectrum of zeolite (B). FIG. 4 shows a powder X-ray diffraction spectrum shown in the literature (Zeolites, Vol. 18, p. 361 (1997)). The overall pattern is in good agreement. Therefore, it was found from FIGS. 3 and 4 that the zeolite (B) of Example 2 had a NU-1 type zeolite crystal structure.

The FT-IR spectrum of zeolite (B) is shown in FIG. 5 (upper diagram, spectrum a), and the UV spectrum is shown in FIG.

When the spectrum a in FIG. 5 is compared with the spectrum b of zeolite A containing no Ti (Example 1),
A characteristic peak is observed at around 960 cm ⁻¹ , and this absorption is considered to be due to the isolated titanyl stabilized with the siloxane ligand, and it is confirmed that Ti is incorporated in the crystal skeleton. Show.

In the UV spectrum of FIG. 6, a large absorption is observed at 220 nm. This is due to tetrahedral coordinated Ti in the skeleton. This shows that most of the Ti is incorporated in the skeleton.

[0047]

According to the synthesis method of the present invention, it is possible to synthesize a NU-1 type zeolite substantially free of aluminum and alkali metal with a high yield even if an inexpensive template is used. Industrial utilization of type-1 zeolite has become possible.

The NU-1 type zeolite obtained by the present invention has a large specific surface area by adsorption of nitrogen of at least 100 m ² / g and a large external surface area of the catalyst.
It is useful as a catalyst having activity in various reactions such as transesterification, and as an adsorbent for various substances.

[Brief description of the drawings]

FIG. 1 shows a powder X-ray diffraction spectrum of the zeolite obtained in Example 1.

FIG. 2 shows a powder X-ray diffraction spectrum of a NU-1 type zeolite (including Al) shown in the literature (Zeolites 18, p. 361 (1997)).

FIG. 3 shows a powder X-ray diffraction spectrum of the zeolite obtained in Example 2.

FIG. 4 shows a powder X-ray diffraction spectrum of a Ti-NU-1 type zeolite (including Al) shown in the literature (Zeolites 18, p. 361 (1997)).

FIG. 5 shows FT-IR spectra of the zeolites obtained in Example 1 (spectrum b) and Example 2 (spectrum a).

FIG. 6 shows a UV spectrum of the zeolite obtained in Example 2.

Continued on the front page F-term (reference) 4G066 AA11D AA14D AA22A AA23A AA61B AB09D AB23A BA26 BA31 BA38 FA17 FA20 FA21 FA34 4G069 AA08 BA07A BA07B BA21A BA21B BA21C BA38 BB04A BB04B BC50A BC50 BE01B35 Z05B01B35 4G073 BA20 BA69 BA75 BB02 BB48 BC10 BD07 CZ53 FC19 FE05 UA03

Claims (7)

[Claims] 1. NU-1 comprising silicon as a metal element
N-type zeolite, characterized in that the zeolite does not contain an alkali metal element and aluminum.
U-1 type zeolite. 2. A NU-1 type zeolite comprising silicon and titanium as a metal element, wherein the zeolite does not contain an alkali metal element and aluminum. 3. The NU-1 type zeolite according to claim 1, wherein the dry gel containing a silicon raw material substantially free of an alkali metal element and aluminum and a mold agent is heat-treated in a steam atmosphere. Manufacturing method. 4. The NU-1 according to claim 2, wherein the dried gel containing a silicon raw material substantially free of an alkali metal element and aluminum, titanium and a mold agent is heat-treated in a steam atmosphere. Method for producing zeolite. 5. The method for producing a NU-1 type zeolite according to claim 4, wherein the titanium source is titanium peroxide. 6. The method for producing a NU-1 type zeolite according to claim 3, wherein the template is a tetraalkylammonium hydroxide. 7. A heat treatment temperature in a steam atmosphere is 150 ° C.
NU-1 according to any one of claims 3 to 6, which is the above.
Method for producing zeolite.