JP5760435B2 - Microcrystalline and highly crystalline β-type zeolite and method for producing the same - Google Patents

Description

In the present invention, the molar ratio of SiO ₂ / Al ₂ O ₃ is 25 or more and 70 or less, the average particle size is 0.05 μm or more and 0.20 μm or less, the carbon content is 0.3% by weight or less, X-ray crystal diffraction (302) The present invention relates to a β-type zeolite having a full width at half maximum (FWHM) of 0.25 ° to 0.90 °, and a method for producing the same.

  β-type zeolite is a zeolite having 12-membered ring pores first disclosed in Patent Document 1, and is widely used as a catalyst and an adsorbent. Also, technical studies have been made on membranes for ion exchangers and catalysts.

  In the case where β-type zeolite is used as a catalyst, a fine particle product is being studied aiming at high activity, high selectivity, high coking resistance and the like.

For example, in Non-Patent Document 1, β-type zeolite made of nanoparticles is compared with commercial β-type zeolite, and the conversion rate of β-type zeolite made of nanoparticles as a hydrocarbon conversion catalyst is higher than that of commercial β-type zeolite at the same temperature. Is reported to be high. The β-type zeolite composed of the nanoparticles uses a tetraethylammonium cation as a structure directing agent (hereinafter abbreviated as “organic SDA”), does not contain an alkali metal, and has a feed composition of Si / Al in a molar ratio. ₂ = 25, OH / Si = TEA / Si = 0.60, H ₂ O / Si = 15, and crystallization is performed under a high OH / Si condition.

Patent Document 2 reports β-type zeolite having particles of about 90 nm and about 50 nm. The β-type zeolite uses a tetraethylammonium cation as an organic SDA, does not contain an alkali metal, and has a raw material composition of Si / Al ₂ = 167 and OH / Si = TEA / Si = 0.56 in a molar ratio. H ₂ O / Si = 7.6, and crystallization is performed under a high OH / Si condition.

Further, Patent Document 3 reports β-type zeolite having an average particle diameter of 40 nm by SEM.
The β-type zeolite uses tetraethylammonium cation as the organic SDA, trimethylcetylammonium bromide as the particle growth regulator, and the raw material composition is Si / Al ₂ = 50, TEA / Si = 0.37, Na /Si=0.072, OH / Si = 0.442, H ₂ O / Si = 17, and crystallization is performed under high OH / Si conditions.

  On the other hand, in the case of using β-type zeolite as a catalyst, it has been studied to increase the crystallite diameter, for example, to reduce the half-value width of the X-ray crystal diffraction (302) plane, aiming at high hydrothermal durability. ing. High hydrothermal durability is a particularly necessary requirement when used as a catalyst for automobiles or when decoking a coking component using a process catalyst such as petrochemicals.

  As an example in which the crystallite diameter is increased in order to increase the hydrothermal durability, in Patent Document 4, the SEM particle size is 0.35 μm or more, and the half width (FWHM) of the X-ray crystal diffraction (302) plane is 0.30. Β-type zeolites of less than ° are reported.

U.S. Pat. No. 3,308,069 Japanese Patent No. 3417944 (Examples 2 and 3) JP2008-239450 (Example 1) JP-A-2008-81348 (Example 1)

R. R. Willis et al. “From Zeolites to Porous MOF Materials”, Proceedings of the 15th International Zeolence Conference, Beijing, China, 2007, Studies in Surface and Science. 242 (2007)

  As described above, fine β-type zeolite that can be expected to have high activity, high selectivity, and high coking resistance, or highly crystalline β-type that has a low half-value width on the X-ray crystal diffraction (302) plane that can be expected to have high hydrothermal durability. Zeolite has been reported, but there was no highly crystalline β-type zeolite having both fine particles and a small half-value width on the X-ray crystal diffraction (302) plane.

In the present invention, the molar ratio of SiO ₂ / Al ₂ O ₃ is 25 or more and 70 or less, the average particle diameter is 0.05 μm or more and 0.20 μm or less, and the full width at half maximum (FWHM) of the X-ray crystal diffraction (302) plane is 0.00. The present invention provides a β-type zeolite of 25 ° or more and 0.90 ° or less. In addition, a method for producing the β-type zeolite is provided.

In view of the above problems, the present inventors have conducted extensive studies on β-type zeolite, and as a result, dissolved Si and Al, and tetraethylammonium containing particles with a peak of mode diameter of 0.01 to 0.2 μm. When the reaction solution containing the cation solution is heated and crystallized, the molar ratio of SiO ₂ / Al ₂ O ₃ is 25 or more and 70 or less, the average particle size of SEM is 0.05 μm or more and 0.20 μm or less, the carbon content Was found to be a new β-type zeolite having an X-ray crystal diffraction (302) plane full width at half maximum (FWHM) of 0.25 ° or more and 0.90 ° or less, thereby completing the present invention. When used as a catalyst, the β-type zeolite of the present invention can be expected to have high activity, high selectivity, high coking resistance, and high hydrothermal durability.

  Hereinafter, the β-type zeolite of the present invention will be described.

In the β-type zeolite of the present invention, it is essential that the SiO ₂ / Al ₂ O ₃ molar ratio is 25 or more and 70 or less. If the SiO ₂ / Al ₂ O ₃ molar ratio is less than 25, the hydrothermal durability is low, and if the SiO ₂ / Al ₂ O ₃ molar ratio is more than 70, the catalyst activity is low, which is not suitable. Moreover, it is preferable that the molar ratio of SiO ₂ / Al ₂ O ₃ is 30 or more and 50 or less from the balance between the acid amount and the acid strength when used as a catalyst.

  The β-type zeolite of the present invention must have an average particle size of 0.05 μm or more and 0.20 μm or less. The average particle diameter of the present invention is obtained as an average of 10 or more particles randomly observed by scanning electron microscope (hereinafter, SEM) observation. The particles observed by SEM are primary particles in which many crystallites are aggregated, and are different from particles in which primary particles are aggregated (so-called secondary particles).

  The β-type zeolite of the present invention has high dispersibility. Therefore, the 50% particle size obtained by measuring the particle size distribution with a laser diffraction scattering device or a dynamic light scattering particle measuring device of a sample that has been subjected to appropriate pretreatment is a value close to the average particle size of SEM.

  When the average particle size is smaller than 0.05 μm, the half width (FWHM) of the X-ray crystal diffraction (302) plane does not become 0.90 ° or less. If the average particle size is larger than 0.20 μm, high activity, high selectivity, and high coking resistance cannot be obtained.

  The β-type zeolite of the present invention must have a carbon content of 0.3% by weight or less. A carbon content of 0.3% by weight or less indicates that substantially no organic SDA such as tetraethylammonium cation is substantially contained. When the amount of carbon exceeds 0.3% by weight, functions when used as a catalyst and an adsorbent are limited. The amount of carbon can be evaluated by CHN elemental analysis or induction furnace combustion-infrared absorption method.

In the β-type zeolite of the present invention, it is essential that the full width at half maximum (FWHM) of the X-ray crystal diffraction (302) plane is 0.25 ° or more and 0.90 ° or less. The full width at half maximum of the present invention is the main peak of the X-ray crystal diffraction (302) plane with CuKα as the X-ray source and appearing in the vicinity of 2θ = 22.4 °. The full width at half maximum is the separation of K _α1 and K _α2 . It refers to a value based on K _α1 later. Making the full width at half maximum (FWHM) of the X-ray crystal diffraction (302) plane smaller than 0.25 ° cannot be realized simultaneously with the average grain size of 0.20 μm or less. When it is larger than 0.90 °, the hydrothermal durability is lowered.

  Since β-type zeolite has a small crystallite when removing organic SDA, organic SDA is substantially reduced from the full width at half maximum (FWHM) of the X-ray crystal diffraction (302) plane of β-type zeolite containing organic SDA. The full width at half maximum of β-type zeolite not contained in is larger.

  Next, a method for producing the β-type zeolite of the present invention will be described.

  The β-type zeolite of the present invention has a mixed solution containing at least a Si source, an Al source, an organic structure directing material (hereinafter referred to as organic SDA), dissolved Si and Al, and a mode particle size of 0.01. It can be produced by hydrothermally treating a reaction solution obtained by mixing a tetraethylammonium cation solution containing particles having a peak of ˜0.2 μm.

  In the production method of the present invention, a mixed solution containing at least a Si source, an Al source, and an organic SDA is prepared.

  Examples of the Si source include silica sol, fumed silica, precipitated silica, silica alumina gel, and tetraethoxylane.

  Examples of the Al source include aluminum hydroxide, pseudoboehmite, alumina sol, silica alumina gel, and aluminum isopropoxide.

  As the organic SDA, at least one of a group of compounds including tetraethylammonium hydroxide having tetraethylammonium cation, tetraethylammonium chloride, and tetraethylammonium bromide can be used. Of these, tetraethylammonium hydroxide aqueous solution and the like are preferable.

  In the production method of the present invention, as a crystallization promoting component, dissolved Si and Al, and tetraethylammonium cation solution containing particles having a peak of mode diameter of 0.01 to 0.2 μm are mixed with the above mixed solution. To obtain a reaction solution.

  The tetraethylammonium cation solution contains particles having a peak with a mode particle diameter of 0.01 to 0.2 μm. By using a tetraethylammonium cation solution containing such particles, crystallization of β-type zeolite is promoted.

  The mode particle diameter of the particles contained in the tetraethylammonium cation solution can be measured as particles having a peak at 0.01 to 0.2 μm in the dynamic light scattering particle measurement.

  The amount of the tetraethylammonium cation solution to be mixed with the above mixture is 0.01 to 25% by weight of the total amount of Si and Al in the tetraethylammonium cation solution to the total amount of Si and Al in the mixture. And is preferably 0.1 to 10% by weight.

  The molar ratio of OH / Si in the reaction solution is preferably OH / Si ≦ 0.3, and more preferably OH / Si ≦ 0.25. By crystallizing a reaction solution of OH / Si ≦ 0.3 and low OH, β-type zeolite containing organic SDA for producing β-type zeolite of the present invention (hereinafter, organic SDA-containing β-type zeolite) is obtained. It becomes easy to obtain. In addition, in a reaction solution having a low OH / Si molar ratio, the solubility of Si and Al is low, so that the yield of β-type zeolite is increased by crystallization thereof. On the other hand, in a reaction solution having a high OH / Si molar ratio exceeding OH / Si = 0.3, it is difficult to satisfy both the average particle diameter and the half width.

  Although the detailed reason why the β-type zeolite of the present invention can be easily obtained by using such a low OH / Si molar ratio reaction solution is unknown, there are few crystal defects by using a low OH / Si molar ratio condition. It is considered that crystals can be obtained.

  In addition, the following range can illustrate the composition of a preferable reaction liquid.

SiO ₂ / Al ₂ O ₃ molar ratio = 10-100
OH / SiO ₂ molar ratio = 0.1 to 0.3
H ₂ O / SiO ₂ molar ratio = 5-50
Organic SDA / SiO ₂ molar ratio = 0.05 to 0.3
Alkali metal / SiO ₂ molar ratio = 0-0.3

  In the production method of the present invention, the reaction solution having the above composition is crystallized in an enclosed pressure vessel at an arbitrary temperature of 100 to 180 ° C. over a sufficient time.

  After completion of crystallization, the mixture is allowed to cool, solid-liquid separation, washed with a sufficient amount of pure water, and dried at an arbitrary temperature of 100 to 150 ° C. to obtain an organic SDA-containing β-type zeolite.

  The β-type zeolite of the present invention can be obtained by removing the organic SDA from the organic SDA-containing β-type zeolite. The organic SDA can be exemplified by removal by baking or decomposition. Examples of firing conditions include 400 to 800 ° C., 0.5 to 12 hours, and a gas flow including oxygen. Examples of the decomposition conditions include contacting an aqueous solution containing 10% or more of hydrogen peroxide containing 100 ppm or more of trivalent Fe at a temperature of room temperature or more for 1 to 24 hours.

  In addition, the β-type zeolite of the present invention can be converted to an ion-exchanged β-type zeolite by exchanging part or all of the ion exchange sites as necessary. The ion-exchanged β-type zeolite is made by bringing the organic SDA-containing β-type zeolite or the β-type zeolite after removal of the organic SDA into contact with an aqueous solution containing ions to be introduced, solid-liquid separation, and washing with pure water as necessary. Can be obtained.

The β-type zeolite of the present invention has a SiO ₂ / Al ₂ O ₃ molar ratio of 25 to 70, an average particle size of 0.05 μm to 0.20 μm, and an X-ray crystal diffraction (302) plane half-width (FWHM). Is a β-type zeolite of 0.25 ° to 0.90 °, and when used as a catalyst, high activity, high selectivity, high coking resistance and high hydrothermal durability can be expected.

1 is a diagram showing a powder X-ray pattern of β-type zeolite prepared in Example 1. FIG. 1 is a view showing an SEM photograph of β-type zeolite prepared in Example 1. FIG. 3 is a diagram showing a powder X-ray pattern of β-type zeolite prepared in Comparative Example 1. FIG. 4 is a view showing an SEM photograph of β-type zeolite prepared in Comparative Example 1. FIG.

  The present invention will be specifically described by the following examples, but the present invention is not limited to these examples. In addition, each measuring method in an Example and a comparative example is as follows.

(Powder X-ray diffraction)
Using the MXP3 system made by Mac Science, X-ray source CuKα, acceleration voltage 40 kV, tube current 30 mA, operation speed 2θ = 0.02 ° / sec, sampling interval 0.02 sec, divergence slit 1 deg, scattering slit 1 deg, light receiving slit 0 .3 mm, using a monochromator, evaluated with a gonio radius of 185 mm.

(Measurement of half-width (FWHM) of (302) plane)
For the profile obtained by powder X-ray diffraction measurement, two peaks (21.6 ° ± 0.5 ° and 22.4 ° ± 0 at 2θ = 22 to 24.5 ° using the program attached to the MXP3 system were used. .5 °). Thereafter, the separation peak at 22.4 ° was further separated into Kα1 and Kα2, and the half width of Kα1 after separation was defined as the half width (FWHM) of the (302) plane.

(Si, Al, Na analysis)
A sample for measurement was dissolved in a mixed aqueous solution of nitric acid and hydrofluoric acid, and evaluated by ICP emission spectroscopic analysis Optima 3000 manufactured by PerkinElmer.

(SEM observation)
JSM-6390LV manufactured by JEOL Ltd. was used.

(Average particle size)
The sample was observed by SEM, and arbitrary 10 or more particles were selected from the obtained SEM photograph. The diameter of the selected particles was measured and averaged to obtain the average particle diameter.

(Carbon content)
A CHN elemental analyzer 2400II manufactured by PerkinElmer was used.

(Si yield)
In beta zeolite synthesis conditions, the solubility of small Al assuming 0 was calculated from the ratio of Si / Al ₂ of the Si / Al ₂ ratio of product feed (beta type zeolite).

Example 1
An amorphous silica alumina gel of Si / Al ₂ = 48, a 35 wt% tetraethylammonium hydroxide (TEAOH) solution, a 48% sodium hydroxide solution, and pure water were mixed to prepare a raw material mixture.

  5% by weight of tetraethylammonium cation solution containing dissolved Si and Al and particles with a peak of mode diameter of 0.01 to 0.2 μm (Si in tetraethylammonium cation solution relative to the total amount of Si and Al in the mixture) And the ratio of the total amount of Al) were added to and mixed with the raw material mixture to obtain a reaction solution.

The tetraethylammonium cation solution has a molar ratio of Si / Al ₂ ratio = 50, H ₂ O / Si ratio = 6.5, TEAOH / Si ratio = 0.40, and a highly transparent viscosity. It is a brown solution.

The charged molar ratio of the reaction solution was as follows: Si / Al ₂ ratio = 48, H ₂ O / Si ratio = 10, TEA / Si ratio = 0.13, Na / Si ratio = 0.10, OH / Si ratio = 0. 23.

  The reaction solution was hydrothermally treated in an autoclave at 150 ° C. for 50 hours, and then crystallized by releasing heat to room temperature. The reaction solution after crystallization was washed with pure water, contacted with a 10% aqueous ammonium chloride solution, washed with pure water, dried at 110 ° C., and further fired at 600 ° C. in air.

  A SEM photograph of the obtained fired powder is shown in FIG. 1, and a powder X-ray diffraction pattern is shown in FIG.

Example 2
A raw material mixture was prepared in the same manner as in Example 1, and a tetraethylammonium cation solution similar to that in Example 1 was added and mixed at 15% by weight to obtain a reaction solution.

The charged molar ratio of the reaction solution was as follows: Si / Al ₂ ratio = 48, H ₂ O / Si ratio = 11, TEA / Si ratio = 0.17, Na / Si ratio = 0.10, OH / Si ratio = 0. 27.

  The reaction solution was hydrothermally treated in an autoclave at 150 ° C. for 50 hours, and crystallized by releasing heat to room temperature. The reaction solution after crystallization was washed with pure water, contacted with a 10% aqueous ammonium chloride solution, washed with pure water, dried at 110 ° C., and further fired at 600 ° C. in air.

Example 3
A raw material mixture was prepared in the same manner as in Example 1, and a tetraethylammonium cation solution similar to that in Example 1 was added and mixed at 15% by weight to obtain a reaction solution.

The charged molar ratio of the reaction solution was as follows: Si / Al ₂ ratio = 48, H ₂ O / Si ratio = 10, TEA / Si ratio = 0.11, Na / Si ratio = 0.10, OH / Si ratio = 0. 21.

  The reaction solution was hydrothermally treated in an autoclave at 150 ° C. for 50 hours, and crystallized by releasing heat to room temperature. The reaction solution after crystallization was washed with pure water, contacted with a 10% aqueous ammonium chloride solution, washed with pure water, dried at 110 ° C., and fired at 600 ° C. in the air.

Reference example 1
Tosoh silica-prepared silica, Sumitomo Chemical aluminum hydroxide, 35 wt% tetraethylammonium hydroxide solution, 48% sodium hydroxide solution, and pure water were mixed to prepare a raw material mixture.

  The same tetraethylammonium cation solution as in Example 1 was added to and mixed with the raw material mixture to prepare a reaction solution.

The charged molar ratio of the reaction solution was as follows: Si / Al ₂ ratio = 28, H ₂ O / Si ratio = 10, TEA / Si ratio = 0.13, Na / Si ratio = 0.10, OH / Si ratio = 0. 23.

  The reaction solution was hydrothermally treated in an autoclave at 150 ° C. for 50 hours, and crystallized by releasing heat to room temperature. The reaction solution after crystallization was washed with pure water, contacted with a 10% aqueous ammonium chloride solution, washed with pure water, dried at 110 ° C., and fired at 600 ° C. in the air.

Reference example 2
A raw material mixture was prepared in the same manner as in Reference Example 1, and 5% by weight of the same tetraethylammonium cation solution as in Example 1 was added and mixed to obtain a reaction solution.

The charged molar ratio of the reaction solution was as follows: Si / Al ₂ ratio = 38, H ₂ O / Si ratio = 10, TEA / Si ratio = 0.11, Na / Si ratio = 0.10, OH / Si ratio = 0. 21.

  The reaction solution was hydrothermally treated in an autoclave at 150 ° C. for 50 hours, and released to room temperature. The reaction solution after crystallization was washed with pure water, contacted with a 10% aqueous ammonium chloride solution, washed with pure water, dried at 110 ° C., and further fired at 600 ° C. in air.

Example 4
Si / Al ₂ ratio = 59 amorphous silica alumina gel, 35 wt% tetraethylammonium hydroxide (TEAOH) solution, 48% sodium hydroxide solution, and pure water were mixed to prepare a raw material mixture. The same tetraethylammonium cation solution as in Example 1 was added to and mixed with the raw material mixture to prepare a reaction solution.

The charged molar ratio of the reaction solution was as follows: Si / Al ₂ ratio = 59, H ₂ O / Si ratio = 10, TEA / Si ratio = 0.13, Na / Si ratio = 0.10, OH / Si ratio = 0. 23.

  The reaction solution was hydrothermally treated in an autoclave at 150 ° C. for 120 hours, and crystallized by releasing heat to room temperature. The reaction solution after crystallization was washed with pure water, contacted with a 10% aqueous ammonium chloride solution, washed with pure water, dried at 110 ° C., and further fired at 600 ° C. in air.

Comparative Example 1
An amorphous silica alumina gel having a Si / Al ₂ ratio = 48, a 35 wt% tetraethylammonium hydroxide (TEAOH) solution, a 48% sodium hydroxide solution, and pure water were mixed to prepare a raw material mixture.

  1 wt% of β-type zeolite HSZ-940NHA manufactured by Tosoh was added to and mixed with the raw material mixture to prepare a reaction solution.

The charged molar ratio of the reaction solution was as follows: Si / Al ₂ ratio = 48, H ₂ O / Si ratio = 10, TEA / Si ratio = 0.33, Na / Si ratio = 0.10, OH / Si ratio = 0. 43.

  The reaction solution was hydrothermally treated in an autoclave at 150 ° C. for 50 hours, and crystallized by releasing heat to room temperature. The reaction solution after crystallization was washed with pure water, contacted with a 10% aqueous ammonium chloride solution, washed with pure water, dried at 110 ° C., and further fired at 600 ° C. in air.

  The SEM photograph of the obtained fired powder is shown in FIG. 3, and the powder X-ray diffraction pattern is shown in FIG.

Comparative Example 2
Using amorphous silica alumina gel with Si / Al ₂ ratio = 59, the reaction molar ratio of the reaction solution was Si / Al ₂ ratio = 59, H ₂ O / Si ratio = 11, TEA / Si ratio = 0.68. The same treatment as in Example 1 was performed except that the Na / Si ratio was 0.10 and the OH / Si ratio was 0.78.

Table 1 shows the crystallization conditions of Examples 1 to 4 , Reference Examples 1 and 2, and Comparative Examples 1 and 2, and various physical properties after removal of organic SDA by firing.

As is apparent from this table, in Examples 1 to 4 having an OH / Si ratio of 0.3 or less, the half width (FWHM) of the X-ray crystal diffraction (302) plane of the obtained β-type zeolite is 0.25. In Comparative Examples 1 and 2 crystallized under the condition that the OH / Si ratio exceeds 0.3 while the temperature falls within the range of 0 ° to 0.90 °, the full width at half maximum (FWHM) of the X-ray crystal diffraction (302) plane ) Is outside the range of the present invention (0.25 ° to 0.90 °).

Further, in Comparative Examples 1 and 2 crystallized under the condition where the OH / Si ratio exceeds 0.3, the yield of β-type zeolite is low, whereas the OH / Si ratio is 0.3 or less. In the crystallized Examples 1 to 4 , the yield of β-type zeolite is high, which is industrially advantageous.

  The β-type zeolite of the present invention can be used as a catalyst and a catalyst base material that are required to have high activity, high selectivity, high coking resistance, and high hydrothermal durability.

Claims (3)

X-rays having a SiO ₂ / Al ₂ O ₃ molar ratio of 40 or more and 70 or less, an average particle size of 0.05 μm or more and 0.20 μm or less, a carbon content of 0.3% by weight or less, and CuKα rays as a radiation source Β-type zeolite having a half-width (FWHM) of crystal diffraction (302) plane of 0.25 ° or more and 0.90 ° or less.   Mixing a mixture containing at least Si source, Al source and organic structure directing material, dissolved Si and Al, and tetraethylammonium cation solution containing particles with a peak of mode diameter of 0.01 to 0.2 μm The method for producing β-type zeolite according to claim 1, wherein the reaction solution is hydrothermally treated.   The production method according to claim 2, wherein the molar ratio of OH / Si in the reaction solution is 0.3 or less.

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