MFI-type zeolite and method for producing the same

Abstract

To provide at least one of: an MFI zeolite that has an excellent handling property when used as a zeolite slurry and has high adsorption performance to organic compounds without requiring use of a dispersant or pulverization; a method for producing the same; and an adsorbent containing the same.SOLUTION: An MFI zeolite is provided which has a D50 in the cumulative volume particle size distribution of 0.5 μm to 5.0 μm inclusive, and a peak height of the (020) plane relative to a peak height of the (101) plane in the powder X-ray diffraction pattern of 65% to 95% inclusive.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This disclosure relates to MFI-type zeolite and a method for producing the same. [Background technology]

[0002] MFI-type zeolites are used in various industrial fields as adsorbents for organic compounds. Generally, when using MFI-type zeolites as adsorbents, it is preferable to reduce the primary particle size and increase the specific surface area from the viewpoint of increasing adsorption efficiency. As an example of an MFI-type zeolite suitable as an adsorbent, Patent Document 1 discloses a pentasil-type zeolite with a primary particle size of about 1 μm obtained by using n-propylamine as a structure-directing agent.

[0003] On the other hand, when the primary particle size is around 5 μm or less, the primary particles tend to aggregate, forming coarse secondary particles. As a result, the viscosity of the zeolite slurry increases, and its handling properties decrease.

[0004] Methods for reducing the particle size of zeolite particles, particularly secondary particles, contained in a slurry include adding a dispersant such as an organic substance to the zeolite slurry (for example, Patent Document 2) and pulverizing the zeolite powder. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2021-11422 [Patent Document 2] Japanese Patent Publication No. 2004-67976 [Overview of the project] [Problems that the invention aims to solve]

[0006] In the MFI-type zeolite disclosed in Patent Document 1, primary particles aggregate significantly, forming coarse particles. Therefore, it was not possible to obtain an MFI-type zeolite with a small average particle size as a powder.

[0007] On the other hand, the method of adding a dispersant as disclosed in Patent Document 2 is undesirable because the dispersant affects the adsorption characteristics of MFI-type zeolite.

[0008] Another method involves pulverizing MFI-type zeolite to reduce its particle size. However, pulverization reduces the crystallinity of the zeolite along with the particle size, thus decreasing its adsorption performance.

[0009] The present disclosure aims to provide at least one of the following: an MFI-type zeolite having a small average particle size and high adsorption performance to organic compounds, a method for producing the same, and an adsorbent containing the same, without requiring the use of a dispersant or grinding. [Means for solving the problem]

[0010] This disclosure describes a method for producing MFI-type zeolite that exhibits excellent handling properties when formed into a zeolite slurry, without the need for grinding or the use of dispersants. As a result, it was discovered that by manipulating the pressure inside a sealed container during the crystallization process of the raw materials, it is possible to directly crystallize MFI-type zeolite that has a small average particle size and high adsorption performance to organic compounds, which could not be obtained by conventional manufacturing methods.

[0011] In other words, the present invention is as described in the claims, and the gist of this disclosure is as follows: [1] An MFI type zeolite in which the D50 in the cumulative volume particle size distribution is 0.5 μm or more and 5.0 μm or less, and in the powder X-ray diffraction pattern, the peak height of the (020) plane is 65% or more and 95% or less compared to the peak height of the (101) plane. [2] The MFI type zeolite described in [1] above, wherein the molar ratio of silica to alumina is 50 or more and 3000 or less. [3] The MFI-type zeolite according to any one of the above [1] or [2], wherein the frequency volume particle size distribution curve is of a monomodal type. [4] The MFI-type zeolite according to any one of the above [1] to [3], wherein the standard deviation in the volume particle size distribution is 10 μm or less. [5] The MFI-type zeolite according to any one of the above [1] to [4], wherein the average crystal diameter is 0.1 μm or more and 5.0 μm or less. [6] BET specific surface area is 300 m 2 / g or more, the MFI-type zeolite according to any one of the above [1] to [5]. [7] A method for producing the MFI-type zeolite according to any one of the above [1] to [6], comprising a step of hydrothermally treating a composition containing a silica source, an alumina source, an alkali source, normal butylamine and water at 100 ° C or higher and 150 ° C or lower, 0.15 MPa or higher, and then hydrothermally treating at 100 ° C or higher and 150 ° C or lower while reducing the pressure at a pressure reduction rate of 0.10 MPa / hour or higher.

Advantages of the Invention

[0012] According to the present disclosure, it is possible to provide at least one of an MFI-type zeolite having excellent handling properties when made into a zeolite slurry and having high adsorption performance for organic compounds, and a method for producing the same, without requiring a method for adding a dispersant or a method for pulverizing zeolite powder.

Modes for Carrying Out the Invention

[0013] Hereinafter, an example of an embodiment of the MFI-type zeolite of the present disclosure will be shown and described. In the present disclosure, each configuration and parameter disclosed in this specification includes any combination, and the upper and lower limits of the values disclosed in this specification include any combination. The terms in this embodiment are as follows.

[0014] Aluminosilicate is a composite oxide having a structure consisting of repeating networks of aluminum (Al) and silicon (Si) mediated by oxygen (O). Among aluminosilicates, those that have crystalline XRD peaks in their powder X-ray diffraction (hereinafter also referred to as "XRD") patterns are called "crystalline aluminosilicate," and those that do not have crystalline XRD peaks are called "amorphous aluminosilicate."

[0015] In this embodiment, the XRD pattern may be obtained from an XRD measurement under the following conditions.

[0016] Acceleration current / voltage: 40mA / 40kV Radiation source: CuKα radiation (λ=1.5405Å) Measurement mode: Continuous scan Scanning conditions: 10° / min Measurement range: 2θ = 5° to 40° Divergence vertical limiting slit: 10mm Divergence / Induction Slit: 1° Scattering slit: Open Light-receiving slit: Open Detector: Semiconductor detector (D / teX Ultra2) Filter: Not used XRD patterns can be measured using a general powder X-ray diffractometer (for example, Ultima IV, manufactured by Rigaku Corporation). Crystalline XRD peaks are peaks whose peak top 2θ is identified and detected in the analysis of the XRD pattern using general analysis software, and examples include XRD peaks with a full width at half maximum of 2θ = 0.10° or less.

[0017] A "zeolite" is a compound in which the skeletal atoms (hereinafter also referred to as "T atoms") have a regular structure mediated by oxygen (O), and the T atoms consist of at least one of a metallic atom and a metalloid atom. Examples of metallic atoms include one or more selected from the group consisting of aluminum (Al), titanium (Ti), iron (Fe), zinc (Zn), gallium (Ga), and tin (Sn), with aluminum being preferred. Examples of metalloid atoms include one or more selected from the group consisting of boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), and tellurium (Te), with silicon being preferred.

[0018] A "zeolite-like substance" is a compound in which the T atom has a regular structure mediated by oxygen, and which contains at least one atom other than a metal or metalloid in the T atom. Examples of zeolite-like substances include aluminophosphate (AlPO) and silicoaluminophosphate (SAPO), which are complex phosphorus compounds containing phosphorus (P) as the T atom.

[0019] The "skeletal structure" (hereinafter also referred to as "zeolite structure") in zeolites and zeolite-like materials is the skeletal structure identified by the skeletal structure code (hereinafter simply referred to as "structure code") established by the Structure Commission of the International Zeolite Association. For example, the MFI structure is a skeletal structure identified by the structure code "MFI". The zeolite structure can be identified by comparing it with the XRD pattern (hereinafter also referred to as "reference pattern") described for MFI in Zeolite Framework Types on the IZA's Structure Commission website: http: / / www.iza-structure.org / databases / . With regard to zeolite structures, the terms skeletal structure, crystalline structure, and crystalline phase are used synonymously.

[0020] In this embodiment, "MFI-type zeolite" and other "~-type zeolites" refer to zeolites having a zeolite structure of the said structural code, preferably crystalline aluminosilicate having a zeolite structure of the said structural code. A zeolite having a zeolite structure of the structural code "MFI" is one whose XRD pattern has an XRD peak that can be identified as an MFI-type zeolite structure, and preferably has at least an XRD peak that can be identified as an MFI-type zeolite structure.

[0021] Each peak in the XRD pattern of an MFI-type zeolite can be attributed to a lattice plane (hkl), (where h, k, and l are integers), by comparing it with a reference pattern.

[0022] "Average crystal diameter" refers to the average value of the particle diameter of primary particles, and primary particles are the smallest particles that can be independently observed in scanning electron microscopy (hereinafter also referred to as "SEM") observation under the following conditions. SEM observation can be performed using a general scanning electron microscope (for example, instrument name: JSM-IT200, manufactured by JEOL Ltd.).

[0023] Acceleration voltage: 6kV Magnification: 10,000±5,000x The average crystal diameter can be determined by first extracting 100 ± 10 primary particles whose outlines are observed without interruption in the SEM observation image, measuring the longest diameter of each extracted primary particle, and calculating the average value. This average value is then used as the average crystal diameter. The number of SEM observation images should be sufficient to observe the aforementioned number of primary particles; one or more SEM observation images may be used.

[0024] "D10," "D50," and "D90" refer to the particle diameter [μm] when the cumulative frequency of particle diameters accounts for 10%, 50%, and 90% of the cumulative frequency of particle diameters in the cumulative volume particle size distribution, respectively. Note that D50 is used interchangeably with "median diameter."

[0025] The cumulative and frequency volume particle size distribution of MFI type zeolite, as well as D10, D50, and D90, can be measured using a general laser diffraction / scattering particle size distribution analyzer (for example, instrument name: Microtrac MT3300EXII, manufactured by Microtrac-Bell Co., Ltd.) under the following conditions.

[0026] Measurement range: 0.02~2000μm Particle refractive index: 1.66 Particle permeability: permeation Particle shape: non-spherical Solvent refractive index: 1.333 "Solid content concentration" refers to the mass ratio of zeolite in the slurry, and is calculated using the following formula.

[0027] Solid content concentration [mass%] = (Zeolite mass [g] / Slurry mass [g]) × 100 In the above formula, the slurry mass is the value obtained by measuring the mass of the slurry. The zeolite mass is the value obtained by drying the slurry after measuring its mass to obtain the solid content, and then measuring its mass after treating it in air at 600°C for 1 hour.

[0028] The MFI-type zeolite of this embodiment will be described below.

[0029] The MFI-type zeolite of this embodiment has a D50 of 0.5 μm or more and 5.0 μm or less, and the peak height of the (020) plane relative to the peak height of the (101) plane in the powder X-ray diffraction pattern (hereinafter also referred to as the "(020) / (101) peak ratio") is 65% or more and 95% or less.

[0030] The MFI-type zeolite of this embodiment has a D50 of 0.5 μm or more and 5.0 μm or less. MFI-type zeolites with a D50 of less than 0.5 μm have high viscosity when made into a slurry and have extremely poor handling (operability). Also, when the D50 exceeds 5.0 μm, the viscosity of the slurry tends to increase at high shear rates and fluidity decreases. The D50 of the MFI-type zeolite of this embodiment is 1.0 μm or more or 1.5 μm or more, and can also be 3.0 μm or less, preferably 1.0 μm or more and 3.0 μm or less, and more preferably 1.5 μm or more and 3.0 μm or less.

[0031] In this embodiment, the MFI-type zeolite preferably has a monomodal frequency-volume-particle-size distribution curve. In this embodiment, a monomodal frequency-volume-particle-size distribution curve means a frequency-volume-particle-size distribution curve having a distribution shape with one peak; in other words, a frequency-volume-particle-size distribution curve obtained by measuring the cumulative volume-particle-size distribution has a shape with one peak, preferably a curve having a shape with one inflection point of particle size frequency in the frequency-volume-particle-size distribution curve.

[0032] In this embodiment, the MFI-type zeolite preferably has a standard deviation (hereinafter also simply referred to as "standard deviation") of 10 μm or less in its volume particle size distribution. The standard deviation of the MFI-type zeolite in this embodiment is 7 μm or less or 5 μm or less, and is greater than 0 μm or 0.5 μm or more, with greater than 0 μm and 7 μm or less being preferred, and 0.5 μm or more and 5 μm or less being more preferred. When the standard deviation satisfies these conditions, the viscosity of the resulting slurry does not increase easily when the MFI-type zeolite in this embodiment is used as a slurry.

[0033] In this embodiment, the "standard deviation" is the value obtained by dividing the difference between D90 and D10 in the cumulative volume particle size distribution by 2, and can be calculated using the following formula.

[0034] Standard deviation [μm]=(D90[μm]-D10[μm]) / 2 The MFI-type zeolite of this embodiment has a (020) / (101) peak ratio of 65% to 95% in its XRD pattern. When the (020) / (101) peak ratio is outside this range, the amount of adsorbed organic compounds decreases. When the MFI-type zeolite is subjected to operations that apply strong stress to the particles, such as grinding, the (020) / (101) peak ratio tends to increase. This is thought to be due to a decrease in the crystallinity of the MFI-type zeolite, and as a result, the amount of adsorbed organic compounds tends to decrease. From the above points, the (020) / (101) peak ratio of the MFI-type zeolite of this embodiment is 70% or more, 75% or more, and 85% or less, with 70% to 85% being preferred and 75% to 85% being more preferred.

[0035] In this embodiment, the MFI-type zeolite preferably has a peak height of the (101) plane relative to the peak height of the (501) plane in its XRD pattern (hereinafter also referred to as the "(101) / (501) peak ratio") of 50% or more and 140% or less. The (101) / (501) peak ratio is considered to be a value attributable to the 10-membered oxygen ring in the skeletal structure of the MFI-type zeolite, and this value tends to increase when the structure-directing agent (hereinafter also referred to as "SDA") or alkali metal elements in the 10-membered oxygen ring are removed by the structure-directing agent removal process and cation exchange process described later. In order to improve the amount of adsorption of organic compounds at equilibrium pressure of 0.01 kPa or higher, the (101) / (501) peak ratio of the MFI-type zeolite in this embodiment is 80% or more or 90% or more, and also 140% or less or 110% or less, with 80% or more and 140% or less being preferred, and 90% or more and 110% or less being more preferred.

[0036] In this embodiment, the "(101) plane peak" refers to an XRD peak corresponding to a lattice plane spacing d of 11.10 ± 0.50 Å in the XRD pattern of the MFI-type zeolite, the "(020) plane peak" refers to an XRD peak corresponding to a lattice plane spacing d of 9.97 ± 0.10 Å in the XRD pattern of the MFI-type zeolite, and the "(501) plane peak" refers to an XRD peak corresponding to a lattice plane spacing d of 3.87 ± 0.03 Å in the XRD pattern of the MFI-type zeolite.

[0037] The XRD pattern does not indicate the crystal structure through individual, independent XRD peaks, but rather through a single XRD pattern consisting of a group of XRD peaks with specific relative intensities, thereby revealing the crystal structure of the MFI-type zeolite. A change in the lattice plane spacing and relative intensity of the XRD peaks means a change in the crystal structure. Therefore, the crystal structure of the MFI-type zeolite in this embodiment can be identified by the group of XRD peaks with these relative intensities. Consequently, a change in the crystal structure causes a change in the lattice plane spacing and relative intensity of the multiple XRD peaks.

[0038] The MFI-type zeolite of this embodiment has an XRD pattern in which an XRD peak is identified as an MFI structure, and preferably has an XRD pattern that includes at least the following XRD peaks.

[0039] [Table 1]

[0040] In this embodiment, the XRD pattern only needs to include each of the XRD peaks in the table above, and may also include other XRD peaks that belong to the MFI structure.

[0041] The MFI-type zeolite of this embodiment more preferably has at least the following XRD peaks in its XRD pattern.

[0042] [Table 2]

[0043] The MFI-type zeolite of this embodiment is more preferably characterized in that its XRD pattern includes at least the following XRD peaks.

[0044] [Table 3]

[0045] In addition to the peaks described above, the MFI-type zeolite of this embodiment may also contain XRD peaks with a relative intensity of less than 1%. However, these low-intensity XRD peaks do not need to be considered for crystal structure identification.

[0046] In this embodiment, the MFI-type zeolite preferably has a molar ratio of silica to alumina (hereinafter also referred to as the "SiO2 / Al2O3 ratio") of 50 to 3000. A SiO2 / Al2O3 ratio of this value tends to result in higher adsorption performance for organic compounds. In terms of easily exhibiting high adsorption characteristics for organic compounds even in the presence of water, the SiO2 / Al2O3 ratio of the MFI-type zeolite in this embodiment is preferably 100 to 3000, more preferably 1000 to 3000, and even more preferably 2000 to 3000. On the other hand, in terms of easily increasing the amount of adsorbed organic compounds, the SiO2 / Al2O3 ratio of the MFI-type zeolite in this embodiment is preferably 50 to 2000, more preferably 100 to 1000, and even more preferably 170 to 500.

[0047] In this embodiment, the MFI-type zeolite is characterized by an improved adsorption capacity for organic compounds, where the ratio of alkali metal content to the total content of silicon (Si), aluminum (Al), and alkali metal (M) (hereinafter also referred to as "metal content") is 0% by mass or more, and is also 0.5% by mass or less, or 0.1% by mass or less. Preferably, it is 0% by mass or more and 0.5% by mass or less, more preferably greater than 0% by mass and 0.1% by mass or less, and even more preferably 0% by mass or more and 0.05% by mass or less.

[0048] If an MFI-type zeolite contains two or more alkali metal elements, the alkali metal content should be the sum of the amounts of each metal element. For example, if the alkali metal elements include sodium (Na) and potassium (K), the alkali metal content should be the ratio of the total amount of sodium and potassium to the total metal content of the MFI-type zeolite (hereinafter also referred to as "(Na+K) content"), which can be calculated as follows.

[0049] (Na+K) content [mass%] ={(Na+K)[g] / (Si+Al+Na+K)[g]}×100 The SiO2 / Al2O3 ratio and alkali metal content can be determined by preparing a sample solution by dissolving MFI-type zeolite in a mixed aqueous solution of hydrofluoric acid and nitric acid, and then measuring the sample solution using inductively coupled plasma atomic emission spectroscopy (ICP-AES) with a general ICP instrument (e.g., instrument name: OPTIMA5300DV, PerkinElmer). The Si, Al, and M values ​​obtained from the measurement results are then used to determine the Si, Al, and M content.

[0050] The MFI-type zeolite of this embodiment may contain SDA in an amount that does not affect its adsorption performance for organic compounds. For example, when the total mass (weighed value) of the MFI-type zeolite containing SDA is taken as 100% by mass, the mass percentage of SDA contained in the MFI-type zeolite (hereinafter also referred to as "SDA content") may be 0% by mass or more and less than 6.0% by mass.

[0051] The average crystal diameter of the MFI-type zeolite of this embodiment is 0.1 μm or more, 0.5 μm or more, or 1.0 μm or more, and may be 5.0 μm or less, 3.0 μm or less, or 1.5 μm or less. It is preferably 0.1 μm or more and 5.0 μm or less, more preferably 0.5 μm or more and 3.0 μm or less, and even more preferably 1.0 μm or more and 1.5 μm or less. When the MFI-type zeolite of this embodiment is in the form of a slurry, the average crystal diameter being the above value makes it likely to exhibit a low viscosity regardless of the shear rate.

[0052] The average crystal diameter is the average diameter of the primary particles of the MFI-type zeolite, which is different from the average diameter of secondary particles including aggregated particles such as D10, D50, and D90. Also, when the frequency volume particle size distribution curve shows a unimodal volume particle size distribution, the average crystal diameter tends to be larger than D10 and smaller than D90. The MFI-type zeolite of this embodiment preferably satisfies D10 < average crystal diameter < D90 (unit: μm), more preferably the frequency volume particle size distribution curve shows a unimodal volume particle size distribution and also satisfies D10 < average crystal diameter < D90 (unit: μm).

[0053] The MFI-type zeolite of this embodiment preferably has a BET specific surface area of 300 m 2 / g or more.

[0054] Since the adsorption amount of organic compounds tends to be large, the BET specific surface area of the MFI-type zeolite of this embodiment is 330 m 2 / g or more, or 350 m 2 / g or more, and may be 800 m 2 / g or less, or 500 m 2 / g or less. It is preferably 330 m 2 / g or more and 800 m 2 / g or less, and more preferably 350 m 2 / g or more and 500 m 2 / g or less.

[0055] The BET specific surface area can be determined by measurement in accordance with JIS Z 8830:2013. Specifically, the BET specific surface area of ​​the sample should be measured using a single-point method with a general-purpose automatic specific surface area measuring device (e.g., device name: BELSORP-miniII, manufactured by Microtrac-Bell Co., Ltd.) and nitrogen as the adsorption gas. As a pretreatment, the sample should be held in a vacuum atmosphere (10 Pa or less) at 350 ± 50°C for 1 to 5 hours.

[0056] The MFI-type zeolite of this embodiment has high crystallinity compared to conventional crystallized MFI-type zeolites, yet has low viscosity when used as a slurry. For example, when the MFI-type zeolite of this embodiment is used as a slurry with pure water as the solvent and a solid content concentration of 51% by mass, it has a viscosity of 1100 s at a shear rate of 1100 s. -1 Examples of viscosity values ​​include 50 mPa·s or less, 30 mPa·s or less, and even 20 mPa·s or less. Low viscosity is preferable, but the shear rate is 1100 s. -1 If the viscosity is 1 mPa·s or higher, and even 3 mPa·s or higher, the fluidity will be suitable for coating the adsorbent onto the carrier.

[0057] In this embodiment, the shear rate is 1100 s. -1 The viscosity can be measured using a general viscometer (e.g., MCR 92, manufactured by Anton Paar) by the following method: Mix MFI type zeolite with pure water to make a zeolite slurry with a solid content of 51% by mass, which is used as the sample slurry. Drop 2 mL of the sample slurry onto the stage of the measuring device fitted with a parallel plate measuring jig (PP50), and measure at a shear rate of 1100 s. -1 The viscosity should be measured. For the measurement, the stage temperature should be 20°C, and the gap between the measuring fixture and the stage should be 0.2 mm.

[0058] In this embodiment, the MFI-type zeolite preferably has an adsorption amount of toluene relative to the mass of the zeolite at an equilibrium pressure of 0.005 kPa (hereinafter also referred to as "toluene adsorption amount") of 5.0 mass or more, more preferably 5.5 mass or more, and even more preferably 6.0 mass or more. Furthermore, the toluene adsorption amount at an equilibrium pressure of 0.01 kPa is preferably 5.0 mass or more, more preferably 6.0 mass or more, and even more preferably 7.0 mass or more. Furthermore, the toluene adsorption amount at an equilibrium pressure of 0.1 kPa is preferably 6.0 mass or more, more preferably 7.0 mass or more, and even more preferably 8.0 mass or more. Furthermore, the toluene adsorption amount at an equilibrium pressure of 1 kPa is preferably 8.0 mass or more, more preferably 8.5 mass or more, and even more preferably 9.0 mass or more. While a higher toluene adsorption amount at each equilibrium pressure is preferable, the upper limit of the physical toluene adsorption amount is 25.0 mass or less or 20.0 mass or less. Furthermore, it is preferable that the toluene adsorption capacity at equilibrium pressures of 0.005 kPa, 0.01 kPa, 0.1 kPa, and 1 kPa all satisfy the above-mentioned values.

[0059] The amount of toluene adsorbed can be measured using a general vapor adsorption measuring device (for example, device name: BELSORP-maxII, manufactured by Microtrac-Bel Co., Ltd.) in the following manner. As a pretreatment, 11 cm 3 Fill a sample tube with 20 ± 10 mg of MFI-type zeolite, and maintain it in a vacuum atmosphere (10 Pa or less) at 350 ± 50°C for 1 to 5 hours to prepare the sample for measurement. Set the sample tube filled with the sample for measurement in a vapor adsorption amount measuring device, change the equilibrium pressure from 0.001 to 1 kPa at 25°C, and measure the amount of toluene adsorbed [mass%] at 0.005 kPa, 0.01 kPa, 0.1 kPa, and 1 kPa.

[0060] The MFI-type zeolite of this embodiment is preferably an aluminosilicate, and more preferably a crystalline aluminosilicate. Therefore, the MFI-type zeolite of this embodiment is preferably phosphorus-free, and even more preferably phosphorus (P) is free of T atoms. The phosphorus content of the MFI-type zeolite of this embodiment is preferably 100 ppm by mass or less, or 1 ppm by mass or less, and also 0 ppm by mass or more, or greater than 0 ppm by mass. Examples include 0 ppm by mass or more and 100 ppm by mass or less, 0 ppm by mass or more and 1 ppm by mass or less, and even greater than 0 ppm by mass and 1 ppm by mass or less.

[0061] Next, the method for producing the MFI-type zeolite of this embodiment will be described.

[0062] The method for producing the MFI-type zeolite of this embodiment includes a step of hydrothermally treating a composition containing a silica source, an alumina source, an alkali source, n-butylamine, and water (hereinafter also referred to as the "raw material composition") at 100°C to 150°C and 0.15 MPa or higher, followed by hydrothermally treating it at 100°C to 150°C while reducing the pressure at a depressurization rate of 0.10 MPa / hour or higher (hereinafter also referred to as the "crystallization step"). Through this crystallization step, the MFI-type zeolite of this embodiment is obtained as a crystalline product from the raw material composition.

[0063] The silica source is at least one of a silicon-containing compound and silicon (Si), and examples include one or more selected from the group consisting of silica sol, fumed silica, colloidal silica, precipitated silica, sodium silicate, potassium silicate, amorphous silica, crystalline aluminosilicate, and amorphous aluminosilicate. From the viewpoint of preventing the D50 of the crystallized MFI-type zeolite from becoming coarse, the silica source is preferably at least one of amorphous silica and amorphous aluminosilicate, and more preferably amorphous aluminosilicate.

[0064] The alumina source is an aluminum compound, for example, one or more selected from the group consisting of aluminum hydroxide, aluminum oxide, aluminum sulfate, sodium aluminate, aluminum chloride, and amorphous aluminosilicate. From the viewpoint of preventing the D50 of the crystallized MFI-type zeolite from becoming coarse, the alumina source is preferably one or more selected from the group consisting of aluminum oxide, aluminum sulfate, sodium aluminate, and amorphous aluminosilicate. From the viewpoint of reactivity, it is more preferably at least one of aluminum sulfate and amorphous aluminosilicate, and even more preferably amorphous aluminosilicate.

[0065] Particularly preferred alumina and silica sources include at least one of amorphous silica, aluminum sulfate, and amorphous aluminosilicate, with amorphous aluminosilicate being preferred. The SiO2 / Al2O3 ratio of the amorphous aluminosilicate is 10 or more, 15 or more, or 20 or more, and 10,000 or less, 1,000 or less, or 80 or less, with 10 to 10,000, 15 to 1,000, or 20 to 80 being preferred.

[0066] Furthermore, if other starting materials contained in the raw material composition contain aluminum, these may also be used as an alumina source. For example, if the silica source contains aluminum, the silica source can be considered simultaneously as an alumina source. An example of such a silica source is an amorphous aluminosilicate in which the aluminum content, calculated as Al2O3, is between 0.001% by mass and 1.000% by mass relative to the total mass of the silica source.

[0067] The alkali source is at least one of an alkali metal element compound and an alkali metal, and includes one or more selected from the group of alkali metal hydroxides, carbonates, sulfates, chlorides, bromides, silicates, and iodides, preferably one or more selected from the group of hydroxides, chlorides, bromides, and iodides, and more preferably a hydroxide.

[0068] Examples of alkali metal elements include one or more selected from the group consisting of sodium, potassium, rubidium, and cesium, with at least one of sodium and potassium being preferred, and sodium being more preferred.

[0069] The raw material composition contains n-butylamine (hereinafter also referred to as "NBA"). This makes it less likely for the D50 of the crystallized MFI-type zeolite to become coarse, and makes it easier to obtain an MFI-type zeolite with high adsorption performance for organic compounds. The raw material composition only needs to contain NBA as an SDA source, and it is preferable that the SDA source is NBA alone. However, it may also contain an SDA source other than NBA that is oriented towards an MFI structure. Examples of SDA sources other than NBA include one or more amines selected from the group consisting of din-butylamine, tributylamine, din-propylamine, tripropylamine, dipropylenetriamine, dihexamethylenetriamine, triethylenetetramine, diethylenetriamine, ethanolamine, and propanolamine, at least one quaternary ammonium cation of tetrapropylammonium and tetraethylammonium, glycerol, alcohols, and morpholin.

[0070] Water may be one or more selected from the group consisting of distilled water, deionized water, and pure water. Furthermore, water derived from other starting materials contained in the raw material composition, such as solvents and water-containing compounds, shall also be considered as water in the raw material composition.

[0071] While the raw material composition does not necessarily have to contain seed crystals in order to reduce raw material costs, it may contain a sufficiently small amount of seed crystals relative to the silica and alumina sources in order to shorten the processing time required for crystallization.

[0072] The seed crystal is preferably an MFI-type zeolite, and the SiO2 / Al2O3 ratio of the MFI-type zeolite is preferably 10 to 4000.

[0073] The seed crystals contained in the raw material composition are such that the ratio of the total mass of aluminum and silicon in the seed crystals (calculated as Al2O3 and SiO2, respectively) to the total mass of aluminum and silicon in the raw material composition (without seed crystals) (calculated as Al2O3 and SiO2, respectively) is 0% by mass or more, or 1% by mass or more, and 20% by mass or less, or 10% by mass or less. Preferred seed crystal contents include 0% by mass or more and 20% by mass or less, greater than 0% by mass and 20% by mass or less, or 1% by mass or more and 10% by mass or less.

[0074] The following molar compositions are considered preferred compositions for the raw material composition.

[0075] SiO2 / Al2O3 ratio = 50 or more, 200 or more, or 1000 or more, 1500 or less, 3000 or less, or 5000 or less NBA / SiO2 ratio = 0.01 or higher, 0.05 or higher, 0.10 or higher, and 0.30 or less, 0.50 or less, 0.70 or less M / SiO2 ratio = 0.01 or higher, 0.05 or higher, or 0.10 or higher, 0.20 or less, 0.40 or less, or 0.60 or less OH / SiO2 ratio = 0.01 or higher, 0.05 or higher, or 0.10 or higher, 0.20 or less, 0.40 or less, or 0.60 or less H2O / SiO2 ratio = 2 or higher, 6 or higher, 8 or higher, and 100 or less, 50 or less, 20 or less However, M represents an alkali metal element. If there are two or more alkali metal elements, M should be the sum of the values ​​of each metal element. For example, if alkali metal element M includes sodium (Na) and potassium (K), then M should be written as (Na + K).

[0076] Particularly preferred compositions of the raw material composition include the following molar compositions.

[0077] SiO2 / Al2O3 ratio = 100 or more and 5000 or less Preferably 200 to 4500 More preferably 1000 to 4500 NBA / SiO2 ratio = 0.05 or more and 0.30 or less Preferably 0.10 or more and 0.30 or less M / SiO2 ratio = 0.01 or more and 0.30 or less Preferably 0.05 or more and 0.20 or less OH / SiO2 ratio = 0.01 or more and 0.30 or less, Preferably 0.05 or more and 0.20 or less H2O / SiO2 ratio =5 or more and 50 or less, Preferably 8 to 15 In this embodiment, it is preferable that the raw material composition does not contain fluorine (F) and fluorine-containing compounds (hereinafter also referred to as "fluorine, etc."). Fluorine, etc. is particularly corrosive, and manufacturing methods using it require special manufacturing equipment that exhibits corrosion resistance. This tends to increase manufacturing costs. Therefore, it is preferable that the raw material composition does not contain fluorine. It is preferable that the fluorine content of the raw material composition is 100 ppm by mass or less, or 1 ppm by mass or less, or 0 ppm by mass or more, or greater than 0 ppm by mass. Examples include 0 ppm by mass or more and 100 ppm by mass or less, 0 ppm by mass or more and 1 ppm by mass or less, and even greater than 0 ppm by mass and 1 ppm by mass or less.

[0078] In the crystallization process, the raw material composition is subjected to hydrothermal treatment at a temperature between 100°C and 150°C and a pressure of 0.15 MPa or higher. This causes the raw material composition to crystallize.

[0079] If the hydrothermal treatment temperature is below 100°C, the time required for crystallization of the raw material composition becomes very long. On the other hand, if it exceeds 150°C, the secondary particle size, especially D50, becomes too large. For this reason, the hydrothermal treatment temperature should be between 100°C and 150°C, and preferably between 115°C and 150°C.

[0080] The pressure for the hydrothermal treatment is 0.15 MPa or higher. If the pressure is less than 0.15 MPa, the resulting MFI-type zeolite will have low crystallinity and low adsorption performance. The hydrothermal treatment pressure is preferably between 0.15 MPa and 0.70 MPa, and more preferably between 0.20 MPa and 0.50 MPa.

[0081] In this embodiment, the pressure (hydrothermal treatment pressure) can be adjusted to the above value, and examples include one or more selected from the group consisting of self-generating pressure, a method of introducing or drawing in an atmospheric gas, and a method of compressing or expanding the volume of a sealed container filled with the raw material composition.

[0082] In this embodiment, the value of pressure (hydrothermal treatment pressure) refers to the absolute pressure. Absolute pressure is expressed as the sum of atmospheric pressure and gauge pressure.

[0083] In hydrothermal treatment, the raw material composition may be in either a stirred or standing state, with stirring being preferred. The stirring speed can be appropriately adjusted depending on the size and structure of the crystallization apparatus, with examples including 30 rpm to 500 rpm, or 40 rpm to 400 rpm.

[0084] The time for hydrothermal treatment can be adjusted according to the amount of raw material composition subjected to hydrothermal treatment and the crystallization temperature. Examples of industrially applicable crystallization times include 5 hours or more, 10 hours or more, 300 hours or less, 200 hours or less, or 100 hours or less, with 5 hours to 300 hours or 10 hours to 50 hours being examples.

[0085] The hydrothermal treatment in the crystallization process is carried out by filling the raw material composition into a sealed container. The sealed container should be able to contain the raw material composition and have sufficient durability against the pressure generated during the hydrothermal treatment.

[0086] In the crystallization process, the raw material is then subjected to hydrothermal treatment at a temperature between 100°C and 150°C while reducing the pressure at a rate of 0.10 MPa / hour or higher (hereinafter also referred to as "reduced pressure hydrothermal treatment"). This allows for the direct crystallization of the MFI-type zeolite having D50 of this embodiment from the raw material composition. The reason why the MFI-type zeolite having D50 of this embodiment can be directly crystallized by performing hydrothermal treatment at the above-mentioned reduction rate and temperature is not clear, but it is thought that reducing the pressure at a rate of 0.10 MPa / hour or higher causes the raw material composition in the sealed container to tumble, suppressing aggregation of crystallized particles, and as a result, it is possible to directly crystallize MFI-type zeolite having a D50 of 0.5 μm or higher and 5.0 μm or lower.

[0087] In the crystallization process, by setting the temperature at which heat treatment is performed under reduced pressure (hereinafter also referred to as the "reduced pressure hydrothermal treatment temperature") to 100°C or higher and 150°C or lower, the MFI type zeolite having D50 of this embodiment can be obtained. If the temperature is below 100°C, the primary particles of the MFI type zeolite tend to aggregate, and D50 becomes excessively large. The reduced pressure hydrothermal treatment temperature is 105°C or higher or 110°C or higher, and also 140°C or lower or 130°C or lower, with 105°C or higher and 140°C or lower being preferred, and 110°C or higher and 130°C or lower being more preferred.

[0088] The depressurization rate in the crystallization process is 0.10 MPa / hour or higher. If the depressurization rate is less than 0.10 MPa / hour, D50 tends to be large. The depressurization rate is preferably 0.10 MPa / hour or higher and 0.30 MPa / hour or lower, and more preferably 0.15 MPa / hour or higher and 0.30 MPa / hour or lower.

[0089] The pressure difference between the start and end of the reduced-pressure hydrothermal treatment is preferably 0.03 MPa or more and 0.40 MPa or less, more preferably 0.10 MPa or more and 0.40 MPa or less, and even more preferably 0.10 MPa or more and 0.35 MPa or less. This makes it easier to reduce D50 and improve the handling properties of the slurry containing MFI type zeolite.

[0090] The initial pressure for the reduced-pressure hydrothermal treatment is preferably 0.15 MPa or more and 0.70 MPa or less, and more preferably 0.20 MPa or more and 0.50 MPa or less.

[0091] After the start of the reduced-pressure hydrothermal treatment, the treatment may be considered complete when the pressure reading remains below the reading ±5 kPa (0.005 MPa) for at least one hour (hereinafter also referred to as the "stable state"). The stable state only needs to last for at least one hour, and examples include one hour to ten hours.

[0092] In the manufacturing method of this embodiment, after the crystallization step, one or more steps selected from the group consisting of a washing step, a drying step, a structure-directing agent removal step, and a cation exchange step may be included.

[0093] In the washing process, the zeolite and the liquid phase are separated into solid and liquid phases. The washing process can be carried out by performing solid and liquid separation using a known method, and then washing the zeolite obtained as the solid phase with pure water.

[0094] In the drying process, moisture physically adsorbed onto the zeolite is removed. The drying conditions are arbitrary, but examples include drying the zeolite in the air at a temperature between 50°C and 250°C for 1 to 120 hours, either by standing or by spray drying.

[0095] The structural directing agent removal process removes SDA contained in the zeolite. Examples of SDA removal methods include one or more selected from the group consisting of resin replacement, thermal decomposition, and calcination. From the viewpoint of manufacturing efficiency, it is preferable that the structural directing agent removal process is at least one of thermal decomposition and calcination. In the case of calcination, the calcination conditions can be appropriately adjusted depending on the amount of zeolite subjected to treatment, but examples include heating in air at 400°C to 700°C for 1 to 24 hours.

[0096] Crystallized MFI-type zeolites may have alkali metal elements originating from an alkali source on their ion exchange sites. In the cation exchange process, these are converted to ammonium cations. Chion (NH 4+ ) and protons (H+ Cation exchange is performed with nonmetallic cations such as ammonium cations. One method for cation exchange to ammonium cations is to contact MFI-type zeolite with an aqueous solution of ammonium chloride. One method for cation exchange to protons is to contact MFI-type zeolite with hydrochloric acid. [Examples]

[0097] The present disclosure will be explained below with reference to examples. However, the present disclosure is not limited to these examples. (Identification of crystalline phases) An XRD pattern was obtained using a powder X-ray diffractometer (instrument name: Ultima IV, manufactured by Rigaku Corporation) under the following conditions.

[0098] Acceleration current / voltage: 40mA / 40kV Radiation source: CuKα radiation (λ=1.5405Å) Measurement mode: Continuous scan Scanning conditions: 10° / min Measurement range: 2θ = 5° to 40° Divergence vertical limiting slit: 10mm Divergence / Induction Slit: 1° Scattering slit: Open Light-receiving slit: Open Detector: Semiconductor detector (D / teX Ultra2) Filter: Not used The crystalline phase of the sample was identified by comparing the obtained XRD patterns with those listed in the MFI section of Zeolite Framework Types on the IZA Structure Committee website (http: / / www.iza-structure.org / databases / ). (Volume particle size distribution) The volume particle size distribution was determined by measuring the frequency curve and integration curve of the volume particle size distribution using a laser diffraction / scattering particle size distribution analyzer (instrument name: Microtrac MT3300EXII, manufactured by Microtrac-Bell Co., Ltd.). The measurement conditions were as follows.

[0099] Measurement range: 0.02~2000μm Particle refractive index: 1.66 Particle permeability: permeation Particle shape: non-spherical Solvent refractive index: 1.333 Ultrasonic pretreatment: None From the obtained cumulative volume particle size distribution, D10, D50, and D90 were obtained. The standard deviation was calculated from the obtained values ​​of D10, D50, and D90 using the following formula.

[0100] Standard deviation [μm]=(D90[μm]-D10[μm]) / 2 We also examined the shape of the frequency-volume-particle-size distribution curve. (Average crystal diameter) SEM observations were performed using a standard scanning electron microscope (device name: JSM-IT200, manufactured by JEOL Ltd.) under the following conditions.

[0101] Acceleration voltage: 6kV Magnification: 10,000±5,000x The average crystal diameter was determined by first extracting 100 ± 10 primary particles whose outlines were observed without interruption in the SEM observation image, measuring the longest diameter of each extracted primary particle, and calculating the average value of these measurements. This was then defined as the average crystal diameter.

[0102] (composition analysis) For compositional 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 atomic emission spectroscopy (ICP-AES) using a general ICP instrument (instrument name: OPTIMA5300DV, PerkinElmer). From the obtained Si, Al, and Na measurements, the SiO2 / Al2O3 ratio and Na content (alkali metal content) of the sample were determined.

[0103] (BET specific surface area) The BET specific surface area of ​​the sample was determined by measurement in accordance with JIS Z 8830:2013. A general specific surface area measuring device (device name: BELSORP-miniII, manufactured by Microtrac-Bel Co., Ltd.) was used for the measurement. As a pretreatment, the sample was held in a vacuum atmosphere (10 Pa or less) at 350°C for 2 hours. For the pretreated sample, nitrogen was used as the adsorption gas and the BET specific surface area was measured using the single-point method.

[0104] (Toluene adsorption amount) The amount of toluene adsorbed was measured using a general vapor adsorption measuring device (device name: BELSORP-MAXII, manufactured by Microtrac-Bel Co., Ltd.) in the following manner. As a pretreatment, 11 cm 3 A sample tube was filled with 20 mg of MFI-type zeolite and held in a vacuum atmosphere (10 Pa or less) at 350°C for 2 hours to prepare the sample for measurement. The sample tube filled with the measurement sample was set in a vapor adsorption measuring device and the equilibrium pressure was varied from 0.001 to 1 kPa at 25°C. The amount of toluene adsorbed [mass%] at equilibrium pressures of 0.005 kPa, 0.01 kPa, 0.1 kPa, and 1 kPa was measured.

[0105] (viscosity measurement) Viscosity was measured using a general-purpose viscometer (device name: MCR 92, manufactured by Anton Paar). The sample was washed, separated into solid and liquid components, and then mixed with pure water to obtain a zeolite slurry with a solid content of 51% by mass, which was used as the sample slurry. 2 mL of the sample slurry was dropped onto the stage of the measuring apparatus fitted with a parallel plate measuring jig (PP50), and the shear rate was set to 100 s. -1 from 1200s -1 The value was changed to a shear rate of 1100 s. -1 The viscosity [mPa·s] was measured. During the measurement, the stage temperature was 20°C, and the gap between the measuring fixture and the stage was 0.2 mm.

[0106] Example 1 NBA, pure water, sodium hydroxide, and amorphous silicic acid with an Al2O3 content of 0.04% by mass were mixed to obtain a raw material composition having the following molar composition.

[0107] SiO2 / Al2O3 ratio =4100 Na / SiO2 ratio =0.11 NBA / SiO2 ratio =0.23 H2O / SiO2 ratio =11 OH / SiO2 ratio =0.11 Seed crystals (MFI-type zeolite, SiO2 / Al2O3 ratio: 2015, manufactured by Tosoh Corporation) were mixed with the raw material composition so that the seed crystal content was 1.0% by mass. Then, 3600g of the raw material composition was filled into a 4L sealed container and subjected to hydrothermal treatment at a pressure of 0.31MPa and 120°C for 24 hours while stirring at 350rpm. After that, the hydrothermal treatment was performed at 120°C while reducing the hydrothermal treatment pressure to 0.20MPa at a depressurization rate of 0.20MPa / hour. After the hydrothermal treatment, the temperature was lowered to 70°C and the crystallized product was recovered, which was used as the MFI-type zeolite of this example.

[0108] The MFI-type zeolite in this embodiment consisted of a single phase with an MFI structure, and was an MFI-type zeolite (crystalline aluminosilicate) with a (020) / (101) peak ratio of 76% and a (101) / (501) peak ratio of 67%. The XRD pattern of this zeolite is shown in the table below.

[0109] [Table 4]

[0110] The MFI-type zeolite in this example has an SiO2 / Al2O3 ratio of 2500, an average crystal diameter of 1.25 μm, a Na content (alkali metal content) of 0.4 mass%, and a BET specific surface area of ​​392 m². 2 The particle size was 0.77 μm for D10, 1.64 μm for D50, and 3.05 μm for D90, with a standard deviation of 1.14 μm. Furthermore, the frequency-volume-particle-size distribution curve was monomodal.

[0111] Example 2 NBA, pure water, sodium hydroxide, and amorphous silicic acid with an Al2O3 content of 0.77% by mass were mixed to obtain a raw material composition having the following molar composition.

[0112] SiO2 / Al2O3 ratio =220 Na / SiO2 ratio =0.11 NBA / SiO2 ratio =0.23 H2O / SiO2 ratio =11 OH / SiO2 ratio =0.11 Seed crystals (MFI-type zeolite, SiO2 / Al2O3 ratio: 2015, manufactured by Tosoh Corporation) were mixed with the raw material composition so that the seed crystal content was 1.0% by mass. Then, 3600g of the raw material composition was filled into a 4L sealed container and subjected to hydrothermal treatment at a pressure of 0.40MPa and 130°C for 36 hours while stirring at 350rpm. After that, hydrothermal treatment was performed at 130°C while reducing the pressure at a rate of 0.20MPa / hour to 0.27MPa. After the hydrothermal treatment, the sealed container was cooled to 70°C and the crystallized product was collected, which was used as the MFI-type zeolite of this example.

[0113] The MFI-type zeolite in this embodiment consisted of a single phase with an MFI structure, and was an MFI-type zeolite (crystalline aluminosilicate) with a (020) / (101) peak ratio of 78% and a (101) / (501) peak ratio of 65%. The XRD pattern of this zeolite is shown in the table below.

[0114] [Table 5]

[0115] The MFI-type zeolite in this example has an SiO2 / Al2O3 ratio of 200, an average crystal diameter of 1.16 μm, a Na content (alkali metal content) of 0.3 mass%, and a BET specific surface area of ​​381 m². 2 The particle size was 1.40 μm for D10, 2.69 μm for D50, and 7.14 μm for D90, with a standard deviation of 2.87 μm. Furthermore, the frequency-volume-particle-size distribution curve was monomodal.

[0116] Example 3 The MFI-type zeolite of Example 1 was brought into contact with 7% by mass hydrochloric acid at 25°C for 5 minutes, washed with pure water, and then solid-liquid separated. The mixture was then dried in an air atmosphere at 110°C for 12 hours to obtain the MFI-type zeolite of this example.

[0117] The MFI-type zeolite in this embodiment consisted of a single phase with an MFI structure, and was an MFI-type zeolite (crystalline aluminosilicate) with a (020) / (101) peak ratio of 82% and a (101) / (501) peak ratio of 105%. The XRD pattern of this zeolite is shown in the table below.

[0118] [Table 6]

[0119] The MFI-type zeolite in this example has an SiO2 / Al2O3 ratio of 2500, an average crystal diameter of 1.25 μm, a Na content (alkali metal content) of 0.01 mass%, and a BET specific surface area of ​​338 m². 2 The particle size was 0.77 μm for D10, 1.64 μm for D50, and 3.05 μm for D90, with a standard deviation of 1.14 μm. Furthermore, the frequency-volume-particle-size distribution curve was monomodal.

[0120] Example 4 The MFI-type zeolite of Example 1 was heat-treated in an air atmosphere at 600°C for 2 hours to obtain the MFI-type zeolite of this example.

[0121] The MFI-type zeolite in this embodiment consisted of a single phase with an MFI structure, and was an MFI-type zeolite (crystalline aluminosilicate) with a (020) / (101) peak ratio of 82% and a (101) / (501) peak ratio of 137%. The XRD pattern of this zeolite is shown in the table below.

[0122] [Table 7]

[0123] The MFI-type zeolite in this example has an SiO2 / Al2O3 ratio of 2500, an average crystal diameter of 1.25 μm, a Na content (alkali metal content) of 0.4 mass%, and a BET specific surface area of ​​392 m². 2 The particle size was 0.77 μm for D10, 1.64 μm for D50, and 3.05 μm for D90, with a standard deviation of 1.14 μm. Furthermore, the frequency-volume-particle-size distribution curve was monomodal.

[0124] Example 5 NBA, pure water, sodium hydroxide, and amorphous silicic acid with an Al2O3 content of 0.08% by mass were mixed to obtain a raw material composition having the following molar composition.

[0125] SiO2 / Al2O3 ratio =2100 Na / SiO2 ratio =0.11 NBA / SiO2 ratio =0.23 H2O / SiO2 ratio =11 OH / SiO2 ratio =0.11 Seed crystals (MFI-type zeolite, SiO2 / Al2O3 ratio: 2015, manufactured by Tosoh Corporation) were mixed with the raw material composition so that the seed crystal content was 1.0% by mass. Then, 3600g of the raw material composition was filled into a 4L sealed container and hydrothermally treated at a pressure of 0.30MPa and 120°C for 36 hours while stirring at 350rpm. After that, the hydrothermal treatment was performed at 120°C while reducing the hydrothermal treatment pressure to 0.20MPa at a depressurization rate of 0.20MPa / hour. After the hydrothermal treatment, the temperature was lowered to 70°C and the crystallized product was recovered, which was used as the MFI-type zeolite of this example.

[0126] The MFI-type zeolite in this embodiment consisted of a single phase with an MFI structure, and was an MFI-type zeolite (crystalline aluminosilicate) with a (020) / (101) peak ratio of 95% and a (101) / (501) peak ratio of 76%. The XRD pattern of this zeolite is shown in the table below.

[0127] [Table 8]

[0128] The MFI-type zeolite in this example has an SiO2 / Al2O3 ratio of 1500, an average crystal diameter of 1.32 μm, a Na content (alkali metal content) of 0.5 mass%, and a BET specific surface area of ​​310 m². 2 The particle size was 1.15 μm for D10, 1.99 μm for D50, and 3.17 μm for D90, with a standard deviation of 1.01 μm. Furthermore, the frequency-volume-particle-size distribution curve was monomodal.

[0129] Comparative Example 1 The raw material composition obtained in the same manner as in Example 1 was subjected to hydrothermal treatment at a pressure of 0.31 MPa and 120°C for 24 hours while stirring at 350 rpm. After the hydrothermal treatment, the temperature was lowered to 30°C, and the crystallized product was recovered, which was used as the MFI-type zeolite of this comparative example.

[0130] The MFI-type zeolite in this comparative example consisted of a single phase with an MFI structure, and was an MFI-type zeolite (crystalline aluminosilicate) with a (020) / (101) peak ratio of 75% and a (101) / (501) peak ratio of 65%. The XRD pattern of this zeolite is shown in the table below.

[0131] [Table 9]

[0132] The MFI-type zeolite in this comparative example has an SiO2 / Al2O3 ratio of 2500, an average crystal diameter of 1.22 μm, a Na content (alkali metal content) of 0.4 mass%, and a BET specific surface area of ​​360 m². 2 The particle size was 2.49 μm for D10, 37.1 μm for D50, and 76.1 μm for D90, with a standard deviation of 36.8 μm. The frequency-volume-particle-size distribution curve was bimodal.

[0133] Comparative Example 2 The raw material composition obtained by the same method as in Example 1 was subjected to hydrothermal treatment at a pressure of 0.31 MPa and 120°C for 24 hours, and then cooled to 70°C. After cooling, hydrothermal treatment was performed at 70°C while reducing the pressure to 0.10 MPa (atmospheric pressure) at a depressurization rate of 0.20 MPa / hour, and the crystallized product was recovered, which was used as the MFI-type zeolite of this comparative example.

[0134] The MFI-type zeolite in this comparative example was confirmed to be an MFI-type zeolite (crystalline aluminosilicate) consisting of a single phase with an MFI structure, and having a (020) / (101) peak ratio of 75% and a (101) / (501) peak ratio of 73%. The XRD pattern of this zeolite is shown in the table below.

[0135] [Table 10]

[0136] The MFI-type zeolite in this comparative example had an SiO2 / Al2O3 ratio of 2600, an average crystal diameter of 1.29 μm, a Na content (alkali metal content) of 0.4 mass%, and particle sizes of 1.86 μm for D10, 8.29 μm for D50, and 38.8 μm for D90, with a standard deviation of 18.5 μm. Furthermore, the frequency-volume-particle-size distribution curve was bimodal.

[0137] Comparative Example 3 The MFI-type zeolite of Comparative Example 1 was pulverized by the following method. Specifically, the MFI-type zeolite obtained in Comparative Example 1 was mixed with pure water to obtain a zeolite slurry with a solid content of 30% by mass. Glass beads with a diameter of 1 mm and the zeolite slurry were filled into a wet mill (device name: DYNO-MILL, MULTI LAB, manufactured by WAB) so that the volume of the glass beads was 80% and the volume of the zeolite slurry was 20% relative to the capacity of the mill. The mill was then pulverized at a peripheral speed of 10 m / s for 10 minutes to obtain the pulverized material.

[0138] The obtained pulverized material was brought into contact with 7% by mass hydrochloric acid at 25°C for 5 minutes, washed with pure water, and then solid-liquid separated. After that, it was dried in an air atmosphere at 110°C for 12 hours to obtain the MFI-type zeolite of this comparative example.

[0139] The MFI-type zeolite in this comparative example consisted of a single phase with an MFI structure, and was an MFI-type zeolite (crystalline aluminosilicate) with a (020) / (101) peak ratio of 99% and a (101) / (501) peak ratio of 106%. Compared to the MFI-type zeolite in the example, it was confirmed that the crystallinity of the MFI-type zeolite in this comparative example decreased upon grinding. The XRD patterns of the zeolite in this comparative example are shown in the table below.

[0140] [Table 11]

[0141] The MFI-type zeolite in this comparative example has an SiO2 / Al2O3 ratio of 2500, an average crystal diameter of 0.96 μm, a Na content (alkali metal content) of 0.01 mass%, and a BET specific surface area of ​​320 m². 2 The particle size was 0.52 μm for D10, 0.88 μm for D50, and 1.76 μm for D90, with a standard deviation of 0.62. The frequency-volume-particle-size distribution curve was monomodal.

[0142] Comparative Example 4 NBA, pure water, sodium hydroxide, and amorphous silicic acid with an Al2O3 content of 6.0% by mass were mixed to obtain a raw material composition having the following molar composition.

[0143] SiO2 / Al2O3 ratio =26 Na / SiO2 ratio =0.20 NBA / SiO2 ratio =0.23 H2O / SiO2 ratio =11 OH / SiO2 ratio =0.20 Seed crystals (MFI-type zeolite, SiO2 / Al2O3 ratio: 2015, manufactured by Tosoh Corporation) were mixed with the raw material composition so that the seed crystal content was 1.0% by mass. Then, 3600g of the raw material composition was filled into a 4L sealed container and subjected to hydrothermal treatment at a pressure of 0.41MPa and 150°C for 36 hours while stirring at 350rpm. After that, hydrothermal treatment was performed at 130°C while reducing the pressure to 0.27MPa at a rate of 0.22MPa / hour. After the hydrothermal treatment, the sealed container was cooled to 70°C and the crystallized product was collected, which was used as the MFI-type zeolite of this comparative example.

[0144] The MFI-type zeolite in this comparative example consisted of a single phase with an MFI structure, and was an MFI-type zeolite (crystalline aluminosilicate) with a (020) / (101) peak ratio of 76% and a (101) / (501) peak ratio of 54%. The XRD pattern of this zeolite is shown in the table below.

[0145] [Table 12]

[0146] The MFI-type zeolite in this comparative example had an SiO2 / Al2O3 ratio of 23, an average crystal diameter of less than 0.1 μm, a Na content (alkali metal content) of 2.1% by mass, and a BET specific surface area of ​​298 m². 2 The particle size was 5.38 μm for D10, 33.7 μm for D50, and 74.7 μm for D90, with a standard deviation of 34.7 μm. Furthermore, the frequency-volume-particle-size distribution curve was bimodal.

[0147] Comparative Example 5 NBA, pure water, sodium hydroxide, and amorphous silicic acid with an Al2O3 content of 0.04% by mass were mixed to obtain a raw material composition having the following molar composition.

[0148] SiO2 / Al2O3 ratio =3900 Na / SiO2 ratio =0.11 NBA / SiO2 ratio =0.23 H2O / SiO2 ratio =11 OH / SiO2 ratio =0.11 Seed crystals (MFI-type zeolite, SiO2 / Al2O3 ratio: 2015, manufactured by Tosoh Corporation) were mixed with the raw material composition so that the seed crystal content was 1.0% by mass. Then, 3600g of the raw material composition was filled into a 4L sealed container and subjected to hydrothermal treatment at a pressure of 1.0MPa and 170°C for 36 hours while stirring at 350rpm. After that, the hydrothermal treatment was performed at 130°C while reducing the hydrothermal treatment pressure to 0.27MPa at a depressurization rate of 0.20MPa / hour. After the hydrothermal treatment, the temperature was lowered to 70°C and the crystallized product was collected, which was used as the zeolite for this comparative example.

[0149] The zeolite used in this comparative example was amorphous (non-crystalline aluminosilicate).

[0150] Measurement Example 1 (Viscosity Measurement of Zeolite Slurry) The MFI-type zeolites from Example 1, Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 4 were each mixed with pure water to obtain zeolite slurries with a solid content concentration of 51% by mass, and the viscosity of each zeolite slurry was measured. The results are shown in the table below.

[0151] [Table 13]

[0152] From the table above, the MFI type zeolite in the example is 1100s -1 The viscosity of the zeolite slurry at the shear rate was lower than that of the comparative MFI-type zeolite. Therefore, it was confirmed that the MFI-type zeolite of the example had superior handling properties when prepared as a zeolite slurry without the need for grinding or the use of a dispersant, compared to the comparative MFI-type zeolite.

[0153] Measurement Example 2 (Measurement of Toluene Adsorption Amount) The amount of toluene adsorbed by the MFI-type zeolites of Examples 1 to 5 and Comparative Example 3 was measured. The results are shown in the table below.

[0154] [Table 14]

[0155] From the table above, it was confirmed that the MFI-type zeolite of the example had a higher toluene adsorption capacity at each equilibrium pressure compared to the MFI-type zeolite of the comparative example.

[0156] In Comparative Example 3, the MFI-type zeolite had a (020) / (101) peak ratio exceeding 95%, meaning its crystallinity had decreased. As a result, it was confirmed that the amount of toluene adsorbed decreased at each equilibrium pressure.

[0157] [Table 15]

[0158] In Example 3, since the Na content was 0.1% by mass or less, it was confirmed that the amount of toluene adsorbed increased at each equilibrium pressure compared to Example 1. Furthermore, in Examples 3 and 4, since the (10¹) / (50¹) peak ratio was between 80% and 140%, it was confirmed that the amount of toluene adsorbed at equilibrium pressures of 0.01 kPa or higher was further improved compared to Example 1.

Claims

1. An MFI-type zeolite having a cumulative volume particle size distribution where D50 is 0.5 μm or more and 5.0 μm or less, and in the powder X-ray diffraction pattern, the peak height of the (020) plane is 65% or more and 95% or less relative to the peak height of the (101) plane, the peak height of the (101) plane is 50% or more and 140% or less relative to the peak height of the (501) plane, and the molar ratio of silica to alumina is 50 or more and 3000 or less.

2. The MFI-type zeolite according to claim 1, having at least the following powder X-ray diffraction peaks. Table 1

3. The MFI-type zeolite according to claim 1 or 2, wherein the frequency-volume-particle-size distribution curve is of the monomodal type.

4. The MFI-type zeolite according to claim 1 or 2, wherein the standard deviation, which is the value obtained by dividing the difference between D90 and D10 in the volume particle size distribution by 2, is 10 μm or less.

5. The MFI-type zeolite according to claim 1 or 2, wherein the average crystal diameter is 0.1 μm or more and 5.0 μm or less.

6. BET specific surface area is 300 m ２ The MFI-type zeolite according to claim 1 or 2, wherein the amount is 1 / g or more.

Images