JP2018062444A - Zeolite zts-3 and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel ESV zeolite and further provide a novel method for producing an ESV zeolite.SOLUTION: An ESV zeolite has a molar ratio of alumina to silica of less than 16, and a method for producing an ESV zeolite is characterized by using a diethyl dimethyl ammonium cation as an organic structure-directing agent. Thus, provided is a novel ESV zeolite, ZTS-3.SELECTED DRAWING: Figure 1

Description

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

  Zeolite having an ESV structure (hereinafter also referred to as “ESV type zeolite”) is an artificially synthesized zeolite having a one-dimensional eight-membered ring pore in its skeleton.

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

Non-Patent Document 2 also discloses a method for producing ERS-7 using an N, N-dimethylpiperidinium cation as a structure directing agent, and the raw material gel has a SiO ₂ / Al ₂ O ₃ ratio of 25 or less. ERS-7 as far as obtained when, it is disclosed that the _SiO 2 / _Al 2 _{O 3} ratio of 16 to 22.

Thus, the ESV type zeolites that have been reported so _far, SiO 2 / _Al 2 _{O 3} ratio was only ERS-7 is 16 to 22.

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

  Only ERS-7 has been obtained so far for ESV type zeolite. 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 examined an ESV type zeolite and a method for producing the same. As a result, an ESV type zeolite different from the conventional one was found. Furthermore, the present inventors have found a production method in which ESV-type zeolite can be obtained without using an N, N-dimethylpiperidinium cation.

That is, the gist of the present invention is as follows.
[1] An ESV-type zeolite having a molar ratio of alumina to silica of less than 16.
[2] The ESV zeolite according to [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, wherein a diethyldimethylammonium cation is used as an organic structure directing agent.
[4] A production method according to the above [3], comprising a crystallization step of crystallizing a composition comprising 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.

  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 to obtain an ESV-type zeolite that is less expensive than the conventional one.

3 is an XRD pattern of ZTS-3 in Example 1. FIG. 2 is a scanning electron micrograph of ZTS-3 of Example 1.

  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 “structure code”) defined by the Structure Commission of the International Zeolite Association. This structure is a powder X-ray diffraction (hereinafter referred to as “XRD”) pattern described in Collection of simulated XRD powder patterns for zeolitics, Fifth revised edition (2007), or IZA's structural committee website http: / Www. isa-structure. It can be identified by comparison with any of the XRD patterns described in Zeolite Framework Types of org / databases /.

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

ZTS-3 has a molar ratio of silica to alumina (ratio of SiO ₂ / Al ₂ O ₃ ) of less than 16 and further 15 or less. Due to the relatively low SiO ₂ / Al ₂ O ₃ ratio, ZTS-3 has sufficient acid sites 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, further 10 or more.

Particularly preferred SiO ₂ / Al ₂ O ₃ ratio is 5 or more and less than 16, and further 10 or more and 15 or less.

  It is preferable that the crystal grain of ZTS-3 is 1 micrometer or less, and it is mentioned that they are 0.3 micrometer or more and 1 micrometer or less. In ZTS-3, it is preferable that crystal particles are dispersed as primary particles. By including almost no secondary particles in which the primary particles are physically aggregated, the portion contributing to various catalytic reactions and adsorption reactions increases. Furthermore, it is mentioned that the crystal particle shape is substantially spherical.

  Next, the manufacturing method of the ESV type zeolite of this invention is demonstrated.

The present invention is a process for producing an ESV-type zeolite, wherein a diethyldimethylammonium cation is used 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, diethyldimethylammonium cation (hereinafter also referred to as “DEDMA ⁺ ”) is used as the organic structure directing agent. DEDMA ⁺ is a readily available compound and is less expensive than N, N-dimethylpiperidinium cation. Therefore, the production method of the present invention using DEDMA ⁺ as SDA can be a cheaper production method of ESV-type zeolite than the conventional one. The production method of the present invention is particularly preferably a production method of ZTS-3.

The production method of the present invention is an ESV-type zeolite production method using DEDMA ⁺ as SDA, which comprises a crystallization step of crystallizing a composition comprising a silica source, an alumina source, an SDA source, an alkali source and water. It is preferable to include. Thereby, ESV type zeolite and further ZTS-3 are obtained.

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

  The alumina source is a compound containing aluminum (Al), and includes at least one selected from the group consisting of aluminum hydroxide, aluminum oxide, aluminum sulfate, aluminum chloride, aluminum nitrate, crystalline aluminosilicate, amorphous aluminosilicate, metal aluminum, and aluminum alkoxide. One type is preferable, at least one of crystalline aluminosilicate and amorphous aluminosilicate is preferable, and crystalline aluminosilicate is more preferable.

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 ^+, and is at least one of diethyldimethylammonium halide and diethyldimethylammonium hydroxide, and further diethyldimethylammonium fluoride, diethyldimethylammonium chloride, diethyldimethylammonium bromide and hydroxide. It is preferably at least one member of the group consisting of diethyldimethylammonium, and particularly preferably diethyldimethylammonium hydroxide (hereinafter also referred to as “DEDMAOH”).

  The alkali source is an alkali metal compound, preferably at least one compound consisting of lithium, sodium, potassium, rubidium and cesium, more preferably at least one of potassium or sodium, and even more preferably a compound of sodium. In addition, when the other raw material contained in a raw material composition contains an alkali metal, the said alkali metal can also be used as an alkali source.

  As water contained in the raw material composition, for example, pure water can be used. In addition, each raw material (except water) of a raw material composition can also be used as aqueous solution.

The SiO ₂ / Al ₂ O ₃ ratio of the raw material composition may be 10 or more, and further 25. On the other hand, the SiO ₂ / Al ₂ O ₃ ratio may be 100 or less, further 50, or even 40. Preferred SiO ₂ / Al ₂ O ₃ ratio of the raw material composition is 10 or more and 100 or less, and further 25 or more and 40 or less.

DEDMA ⁺ molar ratio of of silica to the material composition (hereinafter, also referred to as "DEMDA ⁺ / SiO ₂ ratio".) Is 0.1 or more, even the ESV type zeolite if 0.2 or more 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, and further 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 the alkali metal to silica of the raw material composition (hereinafter also referred to as “alkali / SiO ₂ ratio”) is preferably 1.0 or less, and 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 increase. 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, crystallization of ZTS-3 is easily promoted.

The molar ratio of the hydroxide to the silica of the raw material composition (hereinafter also referred to as “OH / SiO ₂ ratio”) may be 1.5 or less, and further 1.0 or less. When the OH / SiO ₂ ratio is 1.5 or less, the yield of ESV-type zeolite tends to increase. 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 of the raw material composition (hereinafter also referred to as “H ₂ O / SiO ₂ ratio”) is preferably 50 or less. If the H ₂ O / SiO ₂ ratio is 50 or less, the ESV zeolite is easily crystallized. _Also, H ₂ O / SiO 2 ratio is less than 30, even crystallization of ZTS-3 by more than 20 is promoted. In order to impart appropriate fluidity to the raw material composition, the H ₂ O / SiO ₂ ratio is preferably 3 or more, and more preferably 5 or more.

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

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

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

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

  The following composition can be given as a particularly preferred molar ratio of the composition of the raw material composition when crystallization of 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, the raw material composition containing each of the above raw materials is hydrothermally synthesized to crystallize it. For crystallization, the raw material composition may be filled in a sealed container and heated.

  In the crystallization step, if the crystallization temperature is 80 ° C. or higher and 200 ° C. or lower, the ESV zeolite is crystallized. As the crystallization temperature increases, crystallization tends to be promoted. However, in the production method of the present invention, ESV-type zeolite can be crystallized even at 150 ° C. or lower, and even 130 ° C. or lower. Further, if 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 is crystallized even if the crystallization time is 10 days or shorter, further 6 days or shorter. Crystallization can be performed in a state in which the raw material composition is stirred or left standing.

  Hereinafter, the present invention will be described with reference to examples. However, the present invention is not limited to these examples. “Ratio” is “molar ratio” unless otherwise specified.

(Identification of crystal structure)
A general X-ray diffractometer (device name: Ultima IV, manufactured by Rigaku Corporation) was used to perform XRD measurement of the sample. A CuKα ray (λ = 1.5405 mm) 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 a 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 apparatus (apparatus name: OPTIMA5300DV, manufactured by PerkinElmer). From the measured values of Si and Al obtained, the SiO ₂ / Al ₂ O ₃ ratio of the sample was determined.

Example 1
Pure water, sodium hydroxide, FAU-type zeolite (SiO ₂ / Al ₂ O ₃ ratio = 30) and DEDMAOH aqueous solution were mixed to obtain a raw material composition having the following composition.

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
The obtained raw material composition was mixed with 5% by weight of CHA-type zeolite as a seed crystal and then filled into a sealed container, and the raw material composition was crystallized under conditions of 130 ° C. and 5 days with this container left still. It was. The raw material composition after crystallization was separated into solid and liquid, washed with pure water, and then dried at 110 ° C. to obtain ZTS-3 of this example.

The zeolite of this example was composed of a single phase having an ESV structure, and the SiO ₂ / Al ₂ O ₃ ratio was 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 ZTS-3 of this example had dispersed crystal grains having a crystal grain size of 1 μm or less and having a substantially spherical shape.

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

ZTS-3 of this example was a single phase having an ESV structure, and the SiO ₂ / Al ₂ O ₃ ratio was 14.5.

Example 3
Other than using sodium chloride in place of sodium hydroxide, making the raw material composition as follows, not mixing CHA-type zeolite into the raw material composition, and setting the crystallization time to 10 days Obtained ZTS-3 of this example in the same manner 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 in this example was a single phase having an ESV structure.

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

Claims (5)

  ESV type zeolite having a molar ratio of alumina to silica of less than 16.   The ESV-type zeolite according to claim 1, wherein the molar ratio of alumina to silica is 5 or more and 15 or less.   A process for producing an ESV-type zeolite, wherein a diethyldimethylammonium cation is used as an organic structure directing agent.   A manufacturing method according to claim 3, comprising a crystallization step of crystallizing a composition comprising a silica source, an alumina source, an alkali source, water and a diethyldimethylammonium cation.   The production method according to claim 4, wherein at least one of the silica source and the alumina source is crystalline aluminosilicate.

Images