JP6946631B2 - Zeolite ZTS-3 and its manufacturing method - Google Patents

Description

The present invention relates to a novel zeolite having an ESV structure and a method for producing the same.

Zeolites having an ESV structure (hereinafter, also referred to as “ESV-type zeolites”) are artificially synthesized zeolites having one-dimensional 8-membered ring pores in their skeletons.

Non-Patent Document 1 is the first reported example of synthesizing an ESV-type zeolite, and discloses that ERS-7, which is an ESV-type zeolite, can be obtained by using an N, N-dimethylpiperidinium cation as a structure-directing agent. doing. In Non-Patent Document 1, the crystallization of ERS-7 is greatly affected by the molar ratio of alumina to silica in the raw material gel (hereinafter, _{also referred to as “SiO 2} / Al ₂ O ₃ ratio”), and SiO _{2 in the raw material gel.} It is also disclosed that ERS-7 can be obtained only when the / Al ₂ O _{3 ratio is around 25.}

Even in non-patent document 2, N, N- ERS-7 production methods that use dimethylpiperidinium cation as structure directing agent are disclosed, _SiO 2 / _Al 2 _{O 3} ratio of the starting materials the gel is 25 or less It is disclosed that ERS-7 is obtained only in the case and its SiO ₂ / Al ₂ O ₃ ratio is 16 to 22.

As described above, the only ESV-type zeolite reported so far _{is ERS-7 having a SiO 2} / Al ₂ O ₃ ratio of 16 to 22.

Chem. Commun. , Pp. 1725-1726 (1998) Proc. 12th International Zeolite Conference, pp. 541-548 (1999)

As for ESV type zeolite, only ERS-7 has been obtained so far. On the other hand, an object of the present invention is to provide a novel ESV type zeolite. Furthermore, another object is to provide a novel method for producing ESV-type zeolite.

The present inventors have studied ESV-type zeolite and a method for producing the same. As a result, we found an ESV-type zeolite different from the conventional one. Furthermore, we have found a production method for obtaining ESV-type zeolite without using N, N-dimethylpiperidinium cation.

That is, the gist of the present invention is as follows.
[1] ESV-type zeolite having a molar ratio of alumina to silica of less than 16.
[2] The ESV-type zeolite according to the above [1], wherein the molar ratio of alumina to silica is 5 or more and 15 or less.
[3] A method for producing an ESV-type zeolite, which comprises using a diethyldimethylammonium cation as an organic structure-directing agent.
[4] The production method according to the above [3], which comprises a crystallization step of crystallizing a composition containing a silica source, an alumina source, an alkali source, water and a diethyldimethylammonium cation.
[5] The production method according to the above [4], wherein at least one of the silica source and the alumina source is crystalline aluminosilicate.

INDUSTRIAL APPLICABILITY According to the present invention, a novel ESV-type zeolite, ZTS-3, can be provided. Furthermore, it is possible to provide a novel method for producing ESV-type zeolite, and it is possible to obtain ESV-type zeolite at a lower cost than before.

It is an XRD pattern of ZTS-3 of Example 1. It is a scanning electron micrograph of ZTS-3 of Example 1. FIG.

Hereinafter, the ESV-type zeolite of the present invention (hereinafter, also referred to as “ZTS-3”) will be described in detail.

ZTS-3 relates to a zeolite having an ESV structure. The ESV structure is a structure defined as an ESV by the IUPAC structure code (hereinafter, also simply referred to as “structural code”) defined by the Structure Communication of the International Zeolite Association. This structure may be the powder X-ray diffraction (hereinafter referred to as "XRD") pattern described in Collection of simulated XRD powder patterns for zeolites, Fifth revised edition (2007), or the homepage of the IZA Structural Committee http: / Www. iza-struture. It can be identified by comparing it with any of the XRD patterns described in Zeolite Framework Types of org / database /.

The crystal structure of ZTS-3 has a structure similar to that of ERS-7. Therefore, ZTS-3 shows the same XRD pattern as ERS-7.

ZTS-3 has a molar ratio of silica to alumina (SiO ₂ / Al ₂ O ₃ ratio) of less than 16 and even less than 15. Due to its relatively low SiO ₂ / Al ₂ O ₃ ratio, ZTS-3 has sufficient acidity when used as various catalysts. Since ZTS-3 is a so-called high silica zeolite, the SiO ₂ / Al ₂ O ₃ ratio is 5 or more, and further 10 or more.

Particularly preferable SiO ₂ / Al ₂ O ₃ ratios include 5 or more and less than 16, and further 10 or more and 15 or less.

The crystal particles of ZTS-3 are preferably 1 μm or less, and preferably 0.3 μm or more and 1 μm or less. In ZTS-3, it is preferable that the crystal particles are dispersed as primary particles. Since the primary particles contain almost no secondary particles that are physically aggregated, there are many parts that contribute to various catalytic reactions and adsorption reactions. Further, the crystal particle shape is substantially spherical.

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

The present invention is a method for producing an ESV-type zeolite, which comprises using a diethyldimethylammonium cation as an organic structure-directing agent. Conventionally, the production of ESV-type zeolite has required the use of N, N-dimethylpiperidinium cation as an organic structure-directing agent (hereinafter, also referred to as “SDA”). However, since the N, N-dimethylpiperidinium cation is an expensive compound, the cost of the production method using the cation is very high. On the other hand, in the production method of the present invention, a diethyldimethylammonium cation (hereinafter, also referred to as ^{“DEDMA +”) is used as the organic structure directing agent.} DEDMA ⁺ is an readily available compound and is inexpensive compared to the N, N-dimethylpiperidinium cation. ^{Therefore, the production method of the present invention using DEDMA +} as the SDA can be a cheaper method for producing ESV-type zeolite as compared with the conventional method. The production method of the present invention is particularly preferably the production method of ZTS-3.

The production method of the present invention is a method for producing ^{an ESV-type zeolite using DEDMA +} as SDA, which comprises a crystallization step of crystallizing a composition containing a silica source, an alumina source, an SDA source, an alkali source, and water. It is preferable to include it. As a result, ESV-type zeolite and further ZTS-3 can be obtained.

The silica source is a compound containing silicon (Si) and is at least one of the group consisting of silica sol, fumed silica, colloidal silica, precipitated silica, amorphous silicic acid, crystalline aluminosilicates and amorphous aluminosilicates. It is preferably at least one of crystalline aluminosilicate and amorphous aluminosilicate, and more preferably crystalline aluminosilicate.

The alumina source is a compound containing aluminum (Al) and is at least in the group consisting of aluminum hydroxide, aluminum oxide, aluminum sulfate, aluminum chloride, aluminum nitrate, crystalline aluminosilicate, amorphous aluminosilicate, metallic aluminum and aluminum alkoxide. It is preferably one kind, preferably at least one of crystalline aluminosilicate or amorphous aluminosilicate, and more preferably crystalline aluminosilicate.

The crystalline aluminosilicate as the silica source or the alumina source is preferably a FAU-type zeolite, and is preferably a FAU-type zeolite having a SiO ₂ / Al ₂ O ₃ ratio of 20 or more and 40 or less.

The SDA source ^{may be a compound containing DEDMA +} , which is at least one of diethyldimethylammonium halide or diethyldimethylammonium hydroxide, as well as diethyldimethylammonium fluoride, diethyldimethylammonium chloride, diethyldimethylammonium bromide and hydroxide. It is preferably at least one of the group consisting of diethyldimethylammonium, and particularly preferably diethyldimethylammonium hydroxide (hereinafter, also referred to as “DEDMAOH”).

The alkali source is a compound of an alkali metal, and at least one compound consisting of a group of lithium, sodium, potassium, rubidium and cesium, further at least one compound of potassium or sodium, and further a compound of sodium are preferable. When the other raw material contained in the raw material composition contains an alkali metal, the alkali metal can also be used as an alkali source.

As the water contained in the raw material composition, for example, pure water can be used. Each raw material (excluding water) of the raw material composition can also be used as an aqueous solution.

_{The SiO 2} / Al ₂ O ₃ ratio of the raw material composition may be 10 or more, more preferably 25. On the other hand, the SiO ₂ / Al ₂ O ₃ ratio may be 100 or less, further 50, and further 40. _{Preferred SiO 2} / Al ₂ O ₃ ratios of the raw material composition include 10 or more and 100 or less, and further 25 or more and 40 or less.

If the molar ratio ^{of DEDMA + to} silica of the raw material composition ^{(hereinafter, also referred to as “DEMDA +} / SiO ₂ ratio”) is 0.1 or more, and further 0.2 or more, the ESV-type zeolite is likely to crystallize. The raw material composition does not need to contain ^{more DEDMA + than necessary, and the DEDMA +} / SiO ₂ ratio may be 2.0 or less, more preferably 1.5 or less. When the DEDMA ⁺ / SiO ₂ ratio is 0.1 or more and 2.0 or less, and further 0.3 or more and 1.5 or less, ZTS-3 is easily crystallized.

The molar ratio of alkali metal to silica in the raw material composition (hereinafter, _{also referred to as “alkali / SiO 2} ratio”) is preferably 1.0 or less, more preferably 0.5 or less. When the alkali / SiO ₂ ratio is 1.0 or less, the yield of ESV-type zeolite tends to be high. If the alkali / SiO ₂ ratio is 0.05 or more and 0.8 or less, and further 0.1 or more and 0.5 or less, the crystallization of ZTS-3 is likely to be promoted.

The molar ratio of hydroxide to silica in the raw material composition (hereinafter, _{also referred to as “OH / SiO 2} ratio”) may be 1.5 or less, more preferably 1.0 or less. When the OH / SiO ₂ ratio is 1.5 or less, the yield of ESV-type zeolite tends to be high. _{The OH / SiO 2} ratio of the raw material composition may be 0.1 or more and 1.5 or less, and further 0.2 or more and 1.0 or less.

The molar ratio _{of water (H 2} O) to silica in the raw material composition _{(hereinafter, also referred to as “H 2} O / SiO ₂ ratio”) is preferably 50 or less. When the H ₂ O / SiO ₂ ratio is 50 or less, the ESV type zeolite is likely to crystallize. Further, when the H ₂ O / SiO ₂ ratio is less than 30 and further 20 or less, the crystallization of ZTS-3 is promoted. _{The H 2} O / SiO ₂ ratio is preferably 3 or more, more preferably 5 or more, in order to impart appropriate fluidity to the raw material composition.

In the crystallization step, seed crystals may be mixed with the raw material composition. By mixing the seed crystals, the nucleation of ESV-type zeolite is promoted, and it can be crystallized in a shorter time.

The seed crystal consists of AEI type zeolite, CHA type zeolite, OFF type zeolite, ERI type zeolite, ESV type zeolite, KFI type zeolite, AFX type zeolite, AFT type zeolite, EAB type zeolite, GME type zeolite, and LEV type zeolite. At least one of the group, and at least one of CHA-type zeolite or ESV-type zeolite, and further CHA-type zeolite can be mentioned.

The content of the seed crystal in the crystallization step is preferably 0% by weight or more and 10% by weight or less, more preferably 0% by weight or more and 5% by weight or less as the content obtained from the following formula, and when the seed crystal is contained. The seed crystal content is preferably more than 0% by weight and 10% by weight or less, and more preferably more than 0% by weight and 5% by weight or less.

Seed crystal content (% by weight) = (W _{Al (seed)} + W _{Si (seed)} ) x 100 / (W _Al + W _Si )
In the above formula, W _Al is the weight of Al in the raw material composition _{converted to Al 2} O _{3 , W Si} is the weight of Si in the raw material composition _{converted to SiO 2} , and W _{Al (seeded)} is Al in the seed crystal. Is converted to Al ₂ O ₃ , and W _{Si (seed)} is the weight obtained by converting Si in the seed crystal to SiO _2.

The following composition can be mentioned as a molar ratio of the composition of a particularly preferable raw material composition when crystallizing ZTS-3.

10 ≤ SiO ₂ / Al ₂ O ₃ ratio ≤ 50
0.1 ≤ DEDMA ⁺ / SiO ₂ ratio ≤ 2.0
0.05 ≤ alkali / SiO ₂ ratio ≤ 1.0
0.1 ≤ OH / SiO ₂ ratio ≤ 1.5
3 ≤ H ₂ O / SiO ₂ ratio ≤ 20
In the crystallization step, a raw material composition containing each of the above raw materials is hydrothermally synthesized to crystallize the raw material composition. For crystallization, the raw material composition may be filled in a closed container and heated.

In the crystallization step, if the crystallization temperature is 80 ° C. or higher and 200 ° C. or lower, the ESV-type zeolite crystallizes. The higher the crystallization temperature, the more the crystallization tends to be promoted. However, in the production method of the present invention, the ESV-type zeolite can be crystallized even at 150 ° C. or lower, and further 130 ° C. or lower. Further, when the crystallization temperature is 80 ° C. or higher and 150 ° C. or lower, and further, 80 ° C. or higher and 140 ° C. or lower, ZTS-3 crystallizes even if the crystallization time is 10 days or less and further 6 days or less. Crystallization can be carried out in a state where the raw material composition is agitated or allowed to stand.

Hereinafter, the present invention will be described with reference to examples. However, the present invention is not limited to these examples. The "ratio" is a "molar ratio" unless otherwise specified.

(Identification of crystal structure)
The XRD measurement of the sample was performed using a general X-ray diffractometer (device name: Ultima IV, manufactured by Rigaku Co., Ltd.). CuKα ray (λ = 1.5405 Å) was used as the radiation source, and the measurement range was 2θ, and the measurement was performed in the range of 3 ° to 43 °.

(Composition analysis)
A sample solution was prepared by dissolving the sample in a mixed aqueous solution of hydrofluoric acid and nitric acid. The sample solution was measured by inductively coupled plasma emission spectroscopy (ICP-AES) using a general ICP device (device name: OPTIMA5300DV, manufactured by PerkinElmer). From the obtained measured values of Si and Al, the SiO ₂ / Al ₂ O ₃ ratio of the sample was determined.

Example 1
Pure water, sodium hydroxide, to obtain a FAU-type zeolite starting material composition having the following composition by mixing _(SiO 2 / _Al 2 _{O 3} ratio = 30) and DEDMAOH solution.

SiO ₂ / Al ₂ O ₃ ratio = 30
DEDMA ⁺ / SiO ₂ ratio = 0.4
Na / SiO ₂ ratio = 0.2
OH / SiO ₂ ratio = 0.6
H ₂ O / SiO ₂ ratio = 5
After mixing 5% by weight of CHA-type zeolite as a seed crystal with the obtained raw material composition, the raw material composition was filled in a closed container, and the raw material composition was crystallized at 130 ° C. for 5 days while the container was allowed to stand. rice field. The raw material composition after crystallization was solid-liquid separated, washed with pure water, and then dried at 110 ° C. to obtain ZTS-3 of this example.

The zeolite of this example consisted of a single phase with an ESV structure and had a SiO ₂ / Al ₂ O ₃ ratio of 14.1. The XRD pattern of ZTS-3 of this example is shown in FIG. 1, and the SEM photograph is shown in FIG. From FIG. 2, it was confirmed that in ZTS-3 of this example, crystal particles having a substantially spherical shape with a crystal particle size of 1 μm or less were dispersed.

Example 2
ZTS-3 of this example was obtained in the same manner as in Example 1 except that CHA-type zeolite was not mixed with the raw material composition and the crystallization time was set to 10 days.

ZTS-3 of this example had a single phase of ESV structure and had a SiO ₂ / Al ₂ O ₃ ratio of 14.5.

Example 3
Except that sodium chloride was used instead of sodium hydroxide, the raw material composition had the following composition, CHA-type zeolite was not mixed with the raw material composition, and the crystallization time was set to 10 days. Obtained ZTS-3 of this example by the same method as in Example 1.

SiO ₂ / Al ₂ O ₃ ratio = 30
DEDMA ⁺ / SiO ₂ ratio = 1.0
Na / SiO ₂ ratio = 0.2
OH / SiO ₂ ratio = 1
H ₂ O / SiO ₂ ratio = 6
It was confirmed that ZTS-3 of this example has a single phase of ESV structure.

The ESV-type zeolite of the present invention can be used as various catalysts and adsorbents.

Claims (5)

An ESV-type zeolite having a molar ratio of silica to alumina of 10 or more and less than 16. The ESV-type zeolite according to claim 1, wherein the molar ratio of silica to alumina is 14.1 or more and 15 or less. A crystallization step of crystallizing a composition containing a silica source, an alumina source, an organic structure-directing agent source, an alkali source and water, using a diethyldimethylammonium cation as the organic structure-directing agent, and silica in the composition. A method for producing an ESV-type zeolite, wherein the molar ratio of alkali metal to alumina is 0.1 or more, and the molar ratio of silica to alumina is 10 or more. The production method according to claim 3, wherein the alkali source is a compound of sodium. The production method according to claim 4, wherein at least one of the silica source and the alumina source is crystalline aluminosilicate.

Images