JP2010030800A - beta-ZEOLITE HAVING LARGE CRYSTALLITE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide β-zeolite having an SiO<SB>2</SB>/Al<SB>2</SB>O<SB>3</SB>molar ratio of 20 to <30 and a crystallite diameter of ≥40 nm, excellent in heat resistance and containing no fluorine. <P>SOLUTION: Until now, β-zeolite having an SiO<SB>2</SB>/Al<SB>2</SB>O<SB>3</SB>molar ratio of 20 to <30 and a crystallite diameter of ≥40 nm is obtained by using fluorine and thereby inevitably contains fluorine in the crystals. When a basic aqueous reaction liquid containing cesium is heated under stirring to cause crystallization, the objective β-zeolite having a crystallite diameter of ≥40 nm and containing no fluorine in the crystals is obtained, and the β-zeolite has high heat resistance while having the SiO<SB>2</SB>/Al<SB>2</SB>O<SB>3</SB>molar ratio of 20 to <30. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention provides a β-type zeolite having large crystallites that is useful as an adsorbent or a catalyst.

  β-type zeolite is a zeolite having 12-membered ring pores disclosed for the first time in Patent Document 1, and is widely used as an adsorbent and a catalyst. However, when used at high temperatures, the catalyst performance may be reduced with the collapse of the zeolite crystal structure, and improvement in heat resistance is required.

  One method for improving heat resistance is to increase the crystallite diameter.

As an example of controlling the crystallite diameter of zeolite, Patent Document 2 discloses a method for producing a faujasite-type zeolite having a SiO ₂ / Al ₂ O ₃ molar ratio of 4 or more and a crystallite diameter of 1400 mm or more. It is disclosed. Patent Document 3 discloses a high heat-resistant β-type characterized in that the SiO ₂ / Al ₂ O ₃ ratio is 80 or more and the particles have a primary particle diameter of 30 nm or more as an average particle diameter. Zeolite is disclosed. Patent Document 4 discloses a NaY-type zeolite having a controlled crystallite diameter. Patent Document 5 discloses a zeolite having a mordenite structure characterized by having a crystallite diameter of 60 nm or less.

On the other hand, it is known that when a fluorine ion is allowed to coexist in a synthetic system, the crystallite size becomes large (Non-patent Document 1). When using zeolite as a catalyst or the like, a lower SiO ₂ / Al ₂ O ₃ molar ratio is preferable from the viewpoint of increasing active sites, but heat resistance tends to be lowered. Therefore, it is conceivable to increase the crystallite at a low SiO ₂ / Al ₂ O ₃ molar ratio, but conventionally, the crystallite cannot be increased without using fluorine. In other words, there was a problem that fluorine remained. Until now, there was no β-type zeolite having a large crystallite diameter without using fluorine at a low SiO ₂ / Al ₂ O ₃ molar ratio (20 to 40).

  Fluorine ions promote corrosion of the equipment, and β-type zeolite containing fluorine in the crystal is affected by fluorine in its use. Therefore, β-free zeolite does not contain fluorine from the viewpoint of the performance of the β-type zeolite and the industrial production process. Type zeolite and its production method are desired.

US Pat. No. 3,308,069 JP-B 63-6487 JP-A-11-228128 JP 2001-58816 A JP 2002-255541 A 1st “R & D for creating creative high-performance materials (molecularly coordinated materials)” (ex-post evaluation), Subcommittee document 5-2, page 92

The present invention has been made in view of the above situation, and β-type zeolite having a fluorine ion content of 0.1% by weight or less (preferably not contained) and a crystallite of 40 nm or more, particularly low SiO ₂ / Al ₂ O. An object of the present invention is to provide a β-type zeolite having a ₃ molar ratio (20 or more and less than 30).

As a result of the present inventors diligently researching to solve the above-mentioned problem, the SiO ₂ / Al ₂ O ₃ molar ratio is 20 or more and less than 30 by heating and crystallizing a basic reaction liquid containing cesium. In spite of being relatively small, the inventors have found that a large β-type zeolite having a crystallite diameter of 40 nm or more can be obtained, and have completed the present invention.

  Hereinafter, the present invention will be described in detail.

  The β-type zeolite of the present invention is a β-type zeolite having a fluorine content of 0.1% by weight or less and a crystallite diameter of 40 nm or more.

  Conventionally, in the production of β-type zeolite having a large crystallite of 40 nm or more, since fluorine ions are used as a mineralizer, only those having a fluorine content exceeding 0.1% by weight have been obtained. Fluorine in such crystals sometimes has an adverse effect on heat resistance.

  The β-type zeolite of the present invention has a crystallite diameter of 40 nm or more with 0.1 wt% or less of fluorine in the crystal, but the upper limit of the crystallite is not particularly limited, but is preferably 50 nm or more and more preferably 60 nm.

In the β-type zeolite of the present invention, the fluorine content is preferably 0.1% by weight or less and 0.05% by weight or less. More preferably, it is not included at all. (The weight% in this case refers to the fluorine content relative to the weight of the zeolite excluding adsorbed moisture)
The crystallite size of the β-type zeolite of the present invention is the Scherrer equation from the half-value width of the diffraction line profile of the (302) plane near 2θ = 22.4 °, which is the main peak of β-zeolite in powder X-ray diffraction. It is obtained by (I).

Crystallite diameter = K × λ / (β ₁ × cos θ) (I)
β ₂ ² = β _M ² -β _O ²
β ₁ = β ₂ × π / 180
K: constant (0.9),
λ: X-ray wavelength (0.15418 nm)
θ: 1/2 of the diffraction angle,
β ₁ : (302) half-width (rad) of crystal plane peak after device correction,
β ₂ : Half-width (°) of (302) crystal plane peak after device correction
β _M : (302) Width at half maximum of crystal plane peak measured value (°)
β _O : Device correction value (°) obtained from Si as a standard material
The full width at half maximum can be obtained by plotting from the Kα1 peak after waveform separation by approximating a peak around 2θ = 22.4 ° by a voigt function and further separating Kα1 and Kα2 (FWHM).

The β-type zeolite of the present invention preferably further has a SiO ₂ / Al ₂ O ₃ molar ratio of 20 or more and less than 30. When the SiO ₂ / Al ₂ O ₃ molar ratio is 30 or more, the active sites when used as a catalyst are reduced, and when it is less than 20, the heat resistance is not sufficient.

  The crystal grain size (SEM particle size) of the β-type zeolite of the present invention is not particularly limited, but is preferably 1 μm or less, particularly preferably 0.5 μm or less from the viewpoint of use as a catalyst or an adsorbent.

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

  The β-type zeolite of the present invention can be produced by heating and crystallizing a basic water reaction solution containing cesium.

  As the silica source as a raw material, sodium silicate aqueous solution, precipitated silica, colloidal silica, fumed silica, aluminosilicate gel, silicon alkoxide such as tetraethoxysilane, and the like can be used.

The state of the aluminum source as a raw material is not particularly limited, and may be any state such as a simple metal, an aqueous solution, an oxide, a hydroxide, a chloride, a nitrate, and a sulfate. The amount of aluminum added is selected so that the SiO ₂ / Al ₂ O ₃ molar ratio is 20 or more and less than 30 in order to make the produced β-type zeolite useful as an adsorbent or a catalyst.

  As structure directing agents, tetraethylammonium hydroxide having tetraethylammonium cation, tetraethylammonium chloride, tetraethylammonium bromide, octamethylenebiskinucridium, α, α′-diquinuclidium-p-xylene, α, α′-diquinuclidium- m-xylene, α, α′-diquinuclidium-o-xylene, 1,4-diazabicyclo [2,2,2] octane, 1,3,3, N, N-pentamethyl-6-azonium bicyclo [3,2 , 1] octane or at least one of the group of compounds containing N, N-diethyl-1,3,3-trimethyl-6-azonium bicyclo [3,2,1] octane cation can be used. Of these, tetraethylammonium hydroxide aqueous solution and the like are preferable.

  The β-type zeolite of the present invention can be produced by heating and crystallizing a basic water reaction solution containing cesium.

Although the kind of cesium is not particularly limited, a simple metal, an aqueous solution, an oxide, a hydroxide, a chloride, a nitrate, a sulfate, or the like can be used. The amount of cesium is not particularly limited, for example, in Cs / SiO ₂ molar ratio of 0.01 to 0.3. Examples may coexist an alkali metal other than cesium.

In the present invention, hydroxide ions are used as mineralizers without using fluorine ions. The method for adding hydroxide ions is not particularly limited, and is preferably added as a structure directing agent or an alkali metal counter anion. Although fluorine may be mixed as an impurity of the raw material, the fluorine content in the reaction solution is preferably F / SiO ₂ <0.01 in terms of a molar ratio with silica.

  In the above range, the composition of the raw material mixture can be exemplified by the following range.

SiO ₂ / _Al 2 _{O 3} molar ratio from 10 to 200
OH / SiO ₂ molar ratio of 0.1 to 1
Molar H ₂ O / SiO ₂ ratio 5-50
Structure directing agent / SiO ₂ molar ratio 0.05-0.3
Cs / SiO ₂ molar ratio of 0.01 to 0.3
The raw material mixture having the above composition is crystallized in a sealed pressure vessel at an arbitrary temperature of 100 to 180 ° C. for a sufficient time. After completion of crystallization, the product is allowed to cool sufficiently, separated into solid and liquid, washed with a sufficient amount of pure water, and dried at an arbitrary temperature of 100 to 150 ° C. to obtain the β-type zeolite according to the present invention.

  During crystallization, the raw material mixture may be mixed and stirred, or may be left standing, but crystallization is preferably performed under stirring.

  In the static synthesis, the crystallite diameter tends to increase, but in the method of the present invention, β-type zeolite having a large crystallite can be obtained even with stirring.

The β-type zeolite of the present invention has a fluorine content in the crystal of 0.1% by weight or less and a large crystallite diameter of 40 nm or more, so the SiO ₂ / Al ₂ O ₃ molar ratio is 20 or more and less than 30 Even when it is relatively small, it has high heat resistance and excellent adsorption performance, and is suitable as a catalyst / adsorption material.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.
<X-ray diffraction method>
Apparatus: MXP3VII manufactured by Mac Science
X-ray source: CuKα = 1.5405 Å Acceleration voltage: 40 kV
Tube current: 30 mA
Scanning speed: 2θ = 0.02 deg / sec
Sampling interval: 0.02 deg
Divergence slit: 1 deg
Scattering slit: 1 deg
Receiving slit: 0.3mm
Monogon using gonio radius: 185mm
<Measurement method of SEM particle size>
SEM device: JSM-T220A manufactured by JEOL Ltd.
Magnification: 15,000 times Example 1
A granular amorphous aluminosilicate was obtained by mixing a sodium silicate aqueous solution and an aluminum sulfate aqueous solution. Add the amorphous aluminosilicate, 35% aqueous solution of tetraethylammonium hydroxide (hereinafter TEAOH), 48% aqueous solution of sodium hydroxide, cesium chloride, water, and β type zeolite (trade name: HSZ930NHA) manufactured by Tosoh The mixture was stirred and mixed. The composition of the reaction mixture was SiO ₂ : 0.03Al ₂ O ₃ : 0.26 TEAOH: 0.1NaOH: 0.1CsCl: 10H ₂ O. The reaction mixture was sealed in a stainless steel autoclave and heated at 150 ° C. with stirring to cause crystallization. The slurry mixture after crystallization was subjected to solid-liquid separation, washed with a sufficient amount of pure water, and dried at 110 ° C. to obtain β-type zeolite.

Example 2
The cesium chloride of Example 1 was replaced with a 50% aqueous solution of cesium hydroxide. The composition of the reaction _{mixture, SiO 2: 0.03Al 2 O 3} : 0.26TEAOH: 0.1NaOH: 0.1CsOH: was 10H ₂ O. Otherwise, the same processing as in Example 1 was performed.

Example 3
The 48% aqueous sodium hydroxide solution and cesium chloride in Example 1 were replaced with a 50% aqueous cesium hydroxide solution. The composition of the reaction mixture was SiO ₂ : 0.03Al ₂ O ₃ : 0.26TEAOH: 0.1CsOH: 10H ₂ O. Otherwise, the same processing as in Example 1 was performed.

Comparative Example 1
The cesium chloride of Example 1 was removed. The composition of the reaction mixture was SiO ₂ : 0.03Al ₂ O ₃ : 0.26TEAOH: 0.1NaOH: 10H ₂ O. Otherwise, the same processing as in Example 1 was performed.

Comparative Example 2
The synthesis was carried out without using the 48% aqueous sodium hydroxide solution of Example 1 and cesium chloride. The composition of the reaction mixture was SiO ₂ : 0.03Al ₂ O ₃ : 0.16TEAOH: 10H ₂ O. Otherwise, the same processing as in Example 1 was performed.

Comparative Example 3
Example 6 of Patent Document 1 was followed. NaAlO ₂ , water, amorphous silica powder (manufactured by Tosoh Silica, product name nip seal VM-3), and TEAOH aqueous solution were used, and seed crystals were not used. The composition of the reaction mixture was SiO ₂ : 0.025Al ₂ O ₃ : 0.62 TEAOH: 0.1NaOH: 20H ₂ O. Otherwise, the same processing as in Example 1 was performed.

Comparative Example 4
According to Example 1 of JP-A-6-287015, a sodium silicate aqueous solution and an aluminum sulfate aqueous solution were mixed to obtain a granular amorphous aluminosilicate. The amorphous aluminosilicate, a 35% TEAOH aqueous solution, sodium hydroxide, potassium hydroxide, and water were added and mixed thoroughly with stirring. The composition of the reaction mixture was SiO ₂ : 0.025Al ₂ O ₃ : 0.5TEAOH: 0.03NaOH: 0.03KOH: 25H ₂ O. This reaction mixture was sealed in a stainless steel autoclave and crystallized by heating at 135 ° C. with stirring. The slurry mixture after crystallization was subjected to solid-liquid separation, washed with a sufficient amount of pure water, and dried at 110 ° C. to obtain β-type zeolite.

Table 1 shows the SiO ₂ / Al ₂ O ₃ molar ratio, crystallite diameter, and SEM particle diameter of the β-type zeolites of Examples 1 to 3 and Comparative Examples 1 to 4.

Claims (5)

Β-type zeolite having a fluorine content of 0.1% by weight or less and a crystallite diameter of 40 nm or more. The β-type zeolite according to claim 1, which does not contain fluorine. The β-type zeolite according to claim 1 or 2, wherein the SiO ₂ / Al ₂ O ₃ molar ratio is 20 or more and less than 30. The method for producing a β-type zeolite according to any one of claims 1 to 3, wherein the basic water reaction solution containing cesium is heated and crystallized. The method according to claim 4, wherein the crystallization is performed with stirring.