MFI 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] The present disclosure relates to an MFI zeolite and a method for producing the same. [Background technology]

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

[0003] On the other hand, when the primary particle size is about 5 μm or less, the primary particles tend to aggregate and form coarse secondary particles, which results in a high viscosity when made into a zeolite slurry, making it difficult to handle.

[0004] Known 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] Patent Publication No. 2021-11422 [Patent Document 2] JP 2004-67976 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the MFI zeolite disclosed in Patent Document 1, primary particles undergo significant aggregation, resulting in the formation of coarse particles, making it impossible to obtain MFI zeolite with a small average particle size as a powder.

[0007] On the other hand, the method of adding a dispersant disclosed in Patent Document 2 is not preferred because the dispersant affects the adsorption properties of MFI zeolite.

[0008] There is also a method of reducing the particle size by crushing MFI zeolite, but crushing reduces the particle size and the crystallinity of the zeolite, which in turn reduces the adsorption performance.

[0009] An object of the present disclosure is to provide at least one of an MFI zeolite that has a small average particle size and high adsorption performance for organic compounds without necessarily requiring the use of a dispersant or pulverization, a method for producing the same, and an adsorbent containing the same. [Means for solving the problem]

[0010] This disclosure has investigated a method for producing MFI zeolite that is easy to handle when made into a zeolite slurry without using pulverization or a dispersant. As a result, it has been found that by manipulating the pressure inside a sealed container in the process of crystallizing the raw materials, it is possible to directly crystallize MFI zeolite that has a small average particle size and high adsorption performance for organic compounds, something that could not be obtained by conventional production methods.

[0011] That is, the present invention is as described in the claims, and the gist of the present disclosure is as follows. [1] An MFI zeolite having a cumulative volume particle size distribution D50 of 0.5 μm or more and 5.0 μm or less, and a powder X-ray diffraction pattern in which the peak height of the (020) plane relative to the peak height of the (101) plane is 65% or more and 95% or less. [2] The MFI zeolite according to [1] above, wherein the molar ratio of silica to alumina is 50 or more and 3,000 or less. [3] The MFI zeolite according to either [1] or [2] above, wherein the frequency volume particle size distribution curve is a monomodal type. [4] The MFI zeolite according to any one of [1] to [3] above, wherein the standard deviation in the volume particle size distribution is 10 μm or less. [5] The MFI zeolite according to any one of [1] to [4] above, having an average crystal size of 0.1 μm or more and 5.0 μm or less. [6] BET specific surface area is 300m 2 / g or more of the MFI zeolite according to any one of [1] to [5]. [7] A method for producing the MFI zeolite according to any one of [1] to [6] above, comprising the steps 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 at 0.15 MPa or higher, and then hydrothermally treating the composition at 100°C or higher and 150°C or lower while reducing the pressure at a reduction rate of 0.10 MPa / hour or higher. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to provide at least one of an MFI zeolite that has excellent handleability when made into a zeolite slurry and has high adsorption performance for organic compounds, without necessarily requiring a method of adding a dispersant or a method of pulverizing zeolite powder, and a method for producing the same. DETAILED DESCRIPTION OF THE INVENTION

[0013] The MFI zeolite of the present disclosure will be described below with reference to an example of an embodiment. In the present disclosure, the configurations and parameters disclosed herein include any combination, and the upper and lower limits of the values disclosed herein include any combination. The terms used in this embodiment are as follows:

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

[0015] In this embodiment, the XRD pattern can be obtained by XRD measurement under the following conditions.

[0016] Acceleration current / voltage: 40mA / 40kV Radiation source: CuKα radiation (λ=1.5405Å) Measurement mode: Continuous scan Scan condition: 10° / min Measurement range: 2θ=5° to 40° Divergence vertical limit slit: 10mm Divergence / entrance slit: 1° Scattering slit: open Receiving slit: open Detector: Semiconductor detector (D / teX Ultra2) Filter: Not used The XRD pattern can be measured using a general powder X-ray diffractometer (for example, the Ultima IV, manufactured by Rigaku Corporation). The crystalline XRD peak is a peak detected by identifying the 2θ of the peak top in an XRD pattern analysis using general analysis software, and an example of such a peak is an XRD peak with a half-width of 2θ = 0.10° or less.

[0017] "Zeolite" refers to a compound having a regular structure in which skeleton atoms (hereinafter also referred to as "T atoms") are connected via oxygen (O), and the T atoms are at least one of metal atoms and metalloid atoms. Examples of metal atoms include one or more atoms 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 atoms 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 having a regular structure in which T atoms are oxygen-mediated, and the T atoms contain at least one atom other than a metal or metalloid. Examples of zeolite-like substances include complex phosphorus compounds containing phosphorus (P) as the T atom, such as aluminophosphate (AlPO) and silicoaluminophosphate (SAPO).

[0019] The "skeletal structure" (hereinafter also referred to as "zeolite structure") of a zeolite or zeolite-like substance is a skeletal structure identified by the skeletal structure code (hereinafter also 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 MFI structure can be identified by comparing it with the XRD pattern (hereinafter also referred to as "reference pattern") listed in the MFI Zeolite Framework Types on the IZA Structure Commission's website http: / / www.iza-structure.org / databases / . With regard to the zeolite structure, the terms skeletal structure, crystalline structure, and crystalline phase are used interchangeably.

[0020] In the present embodiment, "-type zeolite" such as "MFI zeolite" means a zeolite having a zeolite structure with the structure code, and preferably means a crystalline aluminosilicate having a zeolite structure with the structure code. A zeolite having a zeolite structure with the structure code "MFI" is any zeolite having an XRD peak in its XRD pattern that is identified as an MFI zeolite structure, and preferably has at least an XRD peak that can be identified as an MFI zeolite structure.

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

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

[0023] Accelerating voltage: 6 kV Magnification: 10,000±5,000x The average crystal size can be determined by first extracting 100±10 primary particles whose contours are observed without interruption in the SEM image, measuring the longest diameter of each extracted primary particle, and calculating the average value, which can be used as the average crystal size. The number of SEM images may be any number that allows the above-mentioned number of primary particles to be observed, and one or more SEM images may be used.

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

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

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

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

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

[0029] The MFI zeolite of this embodiment has a D50 of 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 relative to the peak height of the (101) plane (hereinafter also referred to as the "(020) / (101) peak ratio") is 65% or more and 95% or less.

[0030] The MFI zeolite of this embodiment has a D50 of 0.5 μm or more and 5.0 μm or less. MFI zeolite with a D50 of less than 0.5 μm has a high viscosity when made into a slurry and has extremely poor handleability (operability). Furthermore, if the D50 exceeds 5.0 μm, the viscosity of the slurry at high shear rates tends to increase, resulting in poor fluidity. The D50 of the MFI zeolite of this embodiment is 1.0 μm or more or 1.5 μm or more, and can 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] The MFI zeolite of the present embodiment preferably has a frequency volume particle size distribution curve of a monomodal type. In the present embodiment, the frequency volume particle size distribution curve being a monomodal type means that the frequency volume particle size distribution curve has a shape with a single peak, in other words, the frequency volume particle size distribution curve obtained by measuring the cumulative volume particle size distribution has a shape with a single peak, preferably a curve having a shape with a single inflection point of the particle diameter frequency in the frequency volume particle size distribution curve.

[0032] The MFI zeolite of this embodiment preferably has a standard deviation in its volume particle size distribution (hereinafter also simply referred to as "standard deviation") of 10 μm or less. The standard deviation of the MFI zeolite of this embodiment is 7 μm or less or 5 μm or less, and may also be greater than 0 μm or greater than 0.5 μm, preferably greater than 0 μm and less than 7 μm, and more preferably 0.5 μm or greater and less than 5 μm. When the standard deviation satisfies this range, when the MFI zeolite of this embodiment is made into a slurry, the viscosity of the resulting slurry is less likely to increase.

[0033] The "standard deviation" in this embodiment is a 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 zeolite of this embodiment has a (020) / (101) peak ratio in its XRD pattern of 65% or more and 95% or less. If the (020) / (101) peak ratio is outside the above range, the amount of organic compounds adsorbed will be small. If MFI zeolite is subjected to an operation that applies strong stress to the particles, such as crushing, the (020) / (101) peak ratio tends to increase. This is thought to be because the crystallinity of the MFI zeolite is reduced, and as a result, the amount of organic compounds adsorbed will tend to be small. From the above points, the (020) / (101) peak ratio of the MFI zeolite of this embodiment can be 70% or more or 75% or more, and can be 85% or less, preferably 70% or more and 85% or less, and more preferably 75% or more and 85% or less.

[0035] In the XRD pattern of the MFI zeolite of this embodiment, the peak height of the (101) plane relative to the peak height of the (501) plane (hereinafter also referred to as the "(101) / (501) peak ratio") is preferably 50% or more and 140% or less. The (101) / (501) peak ratio is thought to be a value attributable to the 10-membered oxygen ring in the framework structure of the MFI zeolite, and this value tends to increase when the structure-directing agent (hereinafter also referred to as "SDA") and alkali metal elements in the 10-membered oxygen ring are removed in the structure-directing agent removal step and cation exchange step described below. Since the adsorption amount of organic compounds at an equilibrium pressure of 0.01 kPa or more is likely to be improved, the (101) / (501) peak ratio of the MFI zeolite of this embodiment is 80% or more or 90% or more, and may be 140% or less or 110% or less, preferably 80% or more and 140% or less, and more preferably 90% or more and 110% or less.

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

[0037] The XRD pattern does not indicate the crystal structure by individual independent XRD peaks themselves, but by a single XRD pattern consisting of a group of multiple XRD peaks having specific relative intensities, and indicates the crystal structure of MFI zeolite. A change in the lattice spacing and relative intensities of the XRD peaks means a change in the crystal structure. Therefore, the crystal structure of the MFI zeolite of this embodiment can be identified by the group of XRD peaks having these relative intensities. Therefore, a change in the crystal structure changes the lattice spacing and relative intensities of the multiple XRD peaks.

[0038] The MFI zeolite of the present embodiment has an XRD peak in its XRD pattern that 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 may include each of the XRD peaks in the above table, and may also include other XRD peaks attributed to the MFI structure.

[0041] It is more preferable that the MFI zeolite of the present embodiment contains at least the following XRD peaks in its XRD pattern.

[0042] [Table 2]

[0043] It is more preferable that the MFI zeolite of the present embodiment contains at least the following XRD peaks in its XRD pattern.

[0044] [Table 3]

[0045] In addition to the above peaks, the MFI zeolite of this embodiment may contain XRD peaks with relative intensities of less than 1%, but these low-intensity XRD peaks do not need to be taken into consideration when identifying the crystal structure.

[0046] The MFI zeolite of this embodiment preferably has a molar ratio of silica to alumina (hereinafter also referred to as the "SiO2 / Al2O3 ratio") of 50 or more and 3000 or less. When the SiO2 / Al2O3 ratio is within the above range, the adsorption performance for organic compounds is likely to be high. In order to easily exhibit high adsorption properties for organic compounds even in the presence of water, the SiO2 / Al2O3 ratio of the MFI zeolite of this embodiment is preferably 100 or more and 3000 or less, more preferably 1000 or more and 3000 or less, and even more preferably 2000 or more and 3000 or less. On the other hand, in order to easily increase the amount of organic compounds adsorbed, the SiO2 / Al2O3 ratio of the MFI zeolite of this embodiment is preferably 50 or more and 2000 or less, more preferably 100 or more and 1000 or less, and even more preferably 170 or more and 500 or less.

[0047] In the MFI zeolite of the present embodiment, the adsorption amount of organic compounds is likely to be improved, so that the ratio of the alkali metal content (hereinafter also referred to as the "alkali metal content") to the total content (hereinafter also referred to as the "metal content") of the silicon (Si) content, aluminum (Al) content, and alkali metal (M) content of the MFI zeolite is 0% by mass or more or more than 0% by mass, and can be 0.5% by mass or less or 0.1% by mass or less, preferably 0% by mass or more and 0.5% by mass or less, more preferably more 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] When MFI zeolite contains two or more alkali metal elements, the alkali metal content may be the total content of each metal element. For example, when the alkali metal elements include sodium (Na) and potassium (K), the alkali metal content may be the ratio of the total content of sodium and potassium to the metal content of the MFI zeolite (hereinafter also referred to as the "(Na+K) content"), and may be calculated as follows.

[0049] (Na+K) content [mass%] ={(Na+K)[g] / (Si+Al+Na+K)[g]}×100 The SiO2 / Al2O3 ratio and the alkali metal content can be determined from the measured values of Si, Al, and M obtained by preparing a sample solution by dissolving MFI zeolite in a mixed aqueous solution of hydrofluoric acid and nitric acid, and measuring the sample solution by inductively coupled plasma atomic emission spectrometry (ICP-AES) using a general ICP device (for example, device name: OPTIMA5300DV, manufactured by PerkinElmer).

[0050] The MFI zeolite of the present embodiment may contain SDA to the extent that it does not affect the adsorption performance for organic compounds. For example, when the total mass (weighed value) of the MFI zeolite including SDA is taken as 100 mass%, the mass ratio of SDA contained in the MFI zeolite (hereinafter also referred to as "SDA content") may be 0 mass% or more and less than 6.0 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, if the average crystal diameter of the MFI-type zeolite is within the above range, it is likely to exhibit a low viscosity regardless of the shear rate.

[0052] Note that 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 the secondary particles including the 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 is likely 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 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 is likely to increase, 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] BET specific surface area can be determined by measurements in accordance with JIS Z 8830:2013. Specifically, the BET specific surface area of a sample can be measured by the single-point method using a general automatic surface area measuring device (e.g., BELSORP-mini II, manufactured by Microtrac-Bell Corporation) and nitrogen as the adsorption gas. As a pretreatment, the sample can be kept in a vacuum atmosphere (10 Pa or less) at 350 ± 50°C for 1 hour to 5 hours.

[0056] The MFI zeolite of the present embodiment has high crystallinity compared to conventional MFI zeolite after crystallization, but when it is made into a slurry, it has a low viscosity. For example, when the MFI zeolite of the present embodiment is made into a slurry using pure water as a solvent and having a solid content concentration of 51 mass%, it has a low viscosity at a shear rate of 1100 s -1 The viscosity at a shear rate of 1100 s is preferably 50 mPa·s or less, 30 mPa·s or less, or even 20 mPa·s or less. -1 If the viscosity at 1 mPa·s or higher, or even 3 mPa·s or higher, the fluidity will be suitable for application to the adsorbent carrier.

[0057] In this embodiment, the shear rate is 1100 s -1 The viscosity of the sample can be measured using a general viscometer (for example, MCR 92, manufactured by Anton Paar) by the following method. MFI zeolite is mixed with pure water to prepare a zeolite slurry with a solid content of 51% by mass, which is used as the sample slurry. 2 mL of the sample slurry is dropped onto the stage of a measuring device equipped with a parallel plate measuring jig (PP50), and the sample is spun at a shear rate of 1100 s. -1 During the measurement, the stage temperature is set to 20°C, and the gap between the measuring jig and the stage is set to 0.2 mm.

[0058] The MFI zeolite of this example preferably has an adsorption amount of toluene relative to the mass of the zeolite (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 at an equilibrium pressure of 0.005 kPa. 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. 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. 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. The higher the toluene adsorption amount at each equilibrium pressure, the better, but the physical upper limit of the toluene adsorption amount is, for example, 25.0 mass% or less or 20.0 mass% or less. Furthermore, it is preferable that the toluene adsorption power 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 adsorption can be measured using a general vapor adsorption measuring device (for example, device name: BELSORP-max II, manufactured by Microtrac-Bell Co., Ltd.) according to the following method. 3 The sample tube is filled with 20±10 mg of MFI zeolite and held in a vacuum atmosphere (10 Pa or less) at 350±50°C for 1 hour to 5 hours to prepare a measurement sample. The sample tube filled with the measurement sample is then set in a vapor adsorption measurement device, and the equilibrium pressure is changed from 0.001 to 1 kPa at 25°C, and the toluene adsorption amount [mass %] is measured at 0.005 kPa, 0.01 kPa, 0.1 kPa, and 1 kPa.

[0060] The MFI zeolite of this embodiment is preferably an aluminosilicate, and more preferably a crystalline aluminosilicate. Therefore, the MFI zeolite of this embodiment preferably does not contain phosphorus, and further preferably does not contain phosphorus (P) as a T atom. The phosphorus content of the MFI zeolite of this embodiment is preferably 100 ppm by mass or less or 1 ppm by mass or less, or 0 ppm by mass or more or more than 0 ppm by mass, and examples thereof 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 further more than 0 ppm by mass and 1 ppm by mass or less.

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

[0062] The method for producing MFI zeolite of this embodiment is a production method including a step of hydrothermally treating a composition containing a silica source, an alumina source, an alkali source, normal butylamine, and water (hereinafter also referred to as the "raw material composition") at 100°C to 150°C and 0.15 MPa or higher, and then hydrothermally treating the composition at 100°C to 150°C while reducing the pressure at a rate of 0.10 MPa / hour or higher (hereinafter also referred to as the "crystallization step"). The crystallization step allows the MFI zeolite of this embodiment to be obtained as a crystallized product from the raw material composition.

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

[0064] The alumina source is an aluminum compound, and is, 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 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, and 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 may be 10 or more, 15 or more, or 20 or more, and 10,000 or less, 1,000 or less, or 80 or less, and is preferably 10 or more and 10,000 or less, 15 or more and 1,000 or less, or 20 or more and 80 or less.

[0066] Furthermore, when another starting material contained in the raw material composition contains aluminum, it may be used as the alumina source. For example, when the silica source contains aluminum, the silica source can also be considered as the alumina source. An example of such a silica source is an amorphous aluminosilicate having an aluminum content, calculated as Al2O3, of 0.001% by mass or more and 1.000% by mass or less, relative to the mass of the entire silica source.

[0067] The alkali source is at least one of a compound containing an alkali metal element and an alkali metal, and examples thereof include one or more selected from the group consisting of hydroxides, carbonates, sulfates, chlorides, bromides, silicates, and iodides of alkali metals. One or more selected from the group consisting of hydroxides, chlorides, bromides, and iodides is preferred, and hydroxides are more preferred.

[0068] The alkali metal element may be 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 normal butylamine (hereinafter also referred to as "NBA"). This makes it difficult for the D50 of the crystallized MFI zeolite to become coarse, making it easier to obtain an MFI zeolite with high adsorption performance for organic compounds. The raw material composition only needs to contain NBA as an SDA source, and preferably the SDA source is NBA alone. However, it may contain an SDA source directing an MFI structure other than NBA. Examples of SDA sources other than NBA include one or more amines selected from the group consisting of di-normal butylamine, tributylamine, di-normal propylamine, tripropylamine, dipropylenetriamine, dihexamethylenetriamine, triethylenetetramine, diethylenetriamine, ethanolamine, and propanolamine; at least one quaternary ammonium cation selected from the group consisting of tetrapropylammonium and tetraethylammonium; and one or more selected from the group consisting of glycerol, alcohols, and morpholine.

[0070] The 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, is also considered to be water in the raw material composition.

[0071] The raw material composition does not need to contain seed crystals in order to reduce raw material costs. However, the raw material composition may contain seed crystals in an amount sufficiently small relative to the silica source and the alumina source in order to shorten the treatment time required for crystallization.

[0072] The seed crystals are preferably MFI zeolite, and the SiO2 / Al2O3 ratio of the MFI zeolite is preferably 10 or more and 4,000 or less.

[0073] The seed crystals contained in the raw material composition have a ratio (hereinafter also referred to as "seed crystal content") of the total mass of aluminum and silicon in the seed crystals, converted into Al2O3 and SiO2, relative to the total mass of aluminum and silicon in the raw material composition (excluding the seed crystals), converted into Al2O3 and SiO2, respectively, of 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 are, for example, 0% by mass or more and 20% by mass or less, more than 0% by mass and 20% by mass or less, or 1% by mass or more and 10% by mass or less.

[0074] The preferred composition of the raw material composition is the following molar composition.

[0075] SiO2 / Al2O3 ratio = 50 or more, 200 or more, or 1000 or more, and 1500 or less, 3000 or less, or 5000 or less NBA / SiO2 ratio = 0.01 or more, 0.05 or more, 0.10 or more, and 0.30 or less, 0.50 or less, 0.70 or less M / SiO2 ratio = 0.01 or more, 0.05 or more, or 0.10 or more, and 0.20 or less, 0.40 or less, or 0.60 or less OH / SiO2 ratio = 0.01 or more, 0.05 or more, or 0.10 or more, and 0.20 or less, 0.40 or less, or 0.60 or less H2O / SiO2 ratio = 2 or more, 6 or more, 8 or more, and 100 or less, 50 or less, 20 or less Here, M represents an alkali metal element. When there are two or more alkali metal elements, M may be the total value of each metal element. For example, when the alkali metal element M includes sodium (Na) and potassium (K), M may be expressed as M:(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 or more and 4500 or less More preferably, 1000 or more and 4500 or less 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, the raw material composition preferably does not contain fluorine (F) or a fluorine-containing compound (hereinafter also referred to as "fluorine, etc."). Fluorine, etc. are particularly corrosive, and a production method using them requires special production equipment that is corrosion-resistant. This tends to increase production costs. Therefore, the raw material composition preferably does not contain fluorine. The fluorine content of the raw material composition is preferably 100 ppm by mass or less or 1 ppm by mass or less, or 0 ppm by mass or more or more than 0 ppm by mass, and examples thereof 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 more than 0 ppm by mass or less.

[0078] In the crystallization step, the raw material composition is subjected to hydrothermal treatment at 100° C. to 150° C. and 0.15 MPa or higher, thereby crystallizing the raw material composition.

[0079] If the hydrothermal treatment temperature is less than 100°C, the time required for crystallization of the raw material composition becomes very long. On the other hand, if the temperature exceeds 150°C, the secondary particle diameter, particularly D50, becomes too large. Therefore, the hydrothermal treatment temperature is 100°C or higher and 150°C or lower, and preferably 115°C or higher and 150°C or lower.

[0080] The pressure of the hydrothermal treatment (hydrothermal treatment pressure) is 0.15 MPa or more. If the pressure is less than 0.15 MPa, the crystallinity of the resulting MFI zeolite will be low, and the adsorption performance will be low. The hydrothermal treatment pressure 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.

[0081] In this embodiment, the pressure (hydrothermal treatment pressure) may be adjusted to the above-mentioned value, and examples thereof include one or more methods selected from the group consisting of autogenous pressure, a method of introducing or sucking 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 value of absolute pressure, which is expressed as the sum of atmospheric pressure and gauge pressure.

[0083] In the hydrothermal treatment, the raw material composition may be stirred or left to stand, preferably stirred. The stirring speed may be adjusted appropriately depending on the scale and structure of the apparatus used for crystallization, and may be, for example, 30 rpm to 500 rpm, or 40 rpm to 400 rpm.

[0084] The time for the hydrothermal treatment may be adjusted depending on the amount of the raw material composition to be subjected to the hydrothermal treatment and the crystallization temperature. Industrially applicable crystallization times are, for example, 5 hours or more or 10 hours or more, and 300 hours or less, 200 hours or less, or 100 hours or less, and examples thereof include 5 hours or more and 300 hours or less, or 10 hours or more and 50 hours or less.

[0085] The hydrothermal treatment in the crystallization step is carried out by filling the raw material composition into a sealed container. The sealed container may be any container that can seal the raw material composition and has sufficient durability against the pressure generated during the hydrothermal treatment.

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

[0087] In the crystallization step, the temperature at which heat treatment is performed while reducing the pressure (hereinafter also referred to as the "reduced-pressure hydrothermal treatment temperature") is set to 100°C or higher and 150°C or lower, thereby obtaining an MFI zeolite having the D50 of this embodiment. If the temperature is lower than 100°C, the primary particles of the MFI zeolite tend to aggregate, resulting in an excessively large D50. The reduced-pressure hydrothermal treatment temperature is 105°C or higher or 110°C or higher, and can be 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 pressure reduction rate in the crystallization step is 0.10 MPa / hour or more. If the pressure reduction rate is less than 0.10 MPa / hour, D50 tends to be large. The pressure reduction rate is preferably 0.10 MPa / hour or more and 0.30 MPa / hour or less, and more preferably 0.15 MPa / hour or more and 0.30 MPa / hour or less.

[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, which tends to make D50 smaller and improve the handleability of the slurry containing MFI zeolite.

[0090] The pressure at the start of 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 reduced pressure hydrothermal treatment is deemed to be finished when the pressure reading is maintained at a reading of less than ±5 kPa (0.005 MPa) (hereinafter also referred to as a "stable state") for at least one hour. The stable state may be maintained for at least one hour, for example, for at least one hour and up to 10 hours.

[0092] The production method of this embodiment may include, 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.

[0093] In the washing step, the zeolite and the liquid phase are separated into solid and liquid phases by a known method, and the zeolite obtained as a solid phase is washed with pure water.

[0094] In the drying step, moisture physically adsorbed on the zeolite is removed. Drying conditions are arbitrary, and examples include drying the zeolite in the air at 50°C to 250°C for 1 hour to 120 hours, by leaving it to stand or by using a spray dryer.

[0095] The structure-directing agent removal step removes SDA contained in the zeolite. Examples of methods for removing SDA include one or more methods selected from the group consisting of exchange treatment with a resin, pyrolysis treatment, and calcination treatment. From the viewpoint of production efficiency, the structure-directing agent removal step is preferably at least one of pyrolysis treatment and calcination treatment. In the case of calcination treatment, the calcination conditions may be appropriately adjusted depending on the amount of zeolite to be treated, and examples include a temperature of 400°C to 700°C in the atmosphere for 1 hour to 24 hours.

[0096] The crystallized MFI zeolite may have alkali metal elements derived from the alkali source on its ion exchange sites. In the cation exchange step, these are converted to ammonium cations. Thione (NH 4+ ) and protons (H+ Cation exchange with non-metallic cations such as ammonium cations can be performed by contacting MFI zeolite with an aqueous ammonium chloride solution. Cation exchange with protons can be performed by contacting MFI zeolite with hydrochloric acid. [Example]

[0097] The present disclosure will be described below with reference to examples, but the present disclosure is not limited to these examples. (Identification of crystalline phases) An XRD pattern was obtained using a powder X-ray diffractometer (device 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 Scan condition: 10° / min Measurement range: 2θ=5° to 40° Divergence vertical limit slit: 10mm Divergence / entrance slit: 1° Scattering slit: open 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 pattern with the XRD pattern listed in the MFI of Zeolite Framework Types on the IZA Structure Committee homepage http: / / www.iza-structure.org / databases / . (Volumetric particle size distribution) The volume particle size distribution was determined by measuring the frequency curve and cumulative curve of the volume particle size distribution using a laser diffraction / scattering particle size distribution analyzer (device name: Microtrac MT3300EXII, manufactured by Microtrac Bell Co., Ltd.). The measurement conditions were as follows:

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

[0100] Standard deviation [μm]=(D90[μm]-D10[μm]) / 2 The shape of the frequency volume particle size distribution curve was also confirmed. (average crystal size) SEM observation was carried out using a general scanning electron microscope (device name: JSM-IT200, manufactured by JEOL Ltd.) under the following conditions.

[0101] Accelerating voltage: 6 kV Magnification: 10,000±5,000x The average crystal diameter was determined by first extracting 100±10 primary particles whose outlines could be observed without interruption in the SEM image, measuring the longest diameter of each extracted primary particle, and calculating the average value.

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

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

[0104] (Toluene adsorption amount) The amount of toluene adsorption was measured using a common vapor adsorption measuring device (device name: BELSORP-MAX II, manufactured by Microtrac-Bell Corporation) in the following manner. 3 The sample tube was filled with 20 mg of MFI zeolite and held in a vacuum atmosphere (10 Pa or less) at 350°C for 2 hours to prepare a measurement sample. The sample tube filled with the measurement sample was set in a vapor adsorption measurement device, and the equilibrium pressure was changed from 0.001 to 1 kPa at 25°C, and the toluene adsorption amount [mass %] was measured at equilibrium pressures of 0.005 kPa, 0.01 kPa, 0.1 kPa, and 1 kPa.

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

[0106] Example 1 NBA, pure water, sodium hydroxide, and amorphous silicic acid containing 0.04% by mass of Al2O3 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 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, and then 3600 g of the raw material composition was filled into a 4 L airtight container and hydrothermally treated at 120°C under a pressure of 0.31 MPa for 24 hours while stirring at 350 rpm. After that, hydrothermal treatment was continued at 120°C while the hydrothermal treatment pressure was reduced to 0.20 MPa at a pressure reduction rate of 0.20 MPa / hour. After the hydrothermal treatment, the temperature was lowered to 70°C, and the crystallized product was recovered, and this was designated as the MFI zeolite of this example.

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

[0109] [Table 4]

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

[0111] Example 2 NBA, pure water, sodium hydroxide, and amorphous silicic acid containing 0.77% by mass of Al2O3 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 zeolite, SiO / AlO ratio: 2015, manufactured by Tosoh Corporation) were mixed with the raw material composition so that the seed crystal content was 1.0% by mass, and then 3600 g of the raw material composition was filled into a 4 L sealed container and hydrothermally treated at 130°C under a pressure of 0.40 MPa for 36 hours while stirring at 350 rpm. After that, hydrothermally treated at 130°C while reducing the pressure to 0.27 MPa at a pressure reduction rate of 0.20 MPa / hour. After the hydrothermal treatment, the sealed container was cooled to 70°C, and the crystallized product was recovered, and this was designated as the MFI zeolite of this example.

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

[0114] [Table 5]

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

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

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

[0118] [Table 6]

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

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

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

[0122] [Table 7]

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

[0124] Example 5 NBA, pure water, sodium hydroxide, and amorphous silicic acid containing 0.08% by mass of Al2O3 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 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, and then 3600 g of the raw material composition was filled into a 4 L airtight container and hydrothermally treated at 120°C under a pressure of 0.30 MPa for 36 hours while stirring at 350 rpm. After that, hydrothermal treatment was continued at 120°C while the hydrothermal treatment pressure was reduced to 0.20 MPa at a pressure reduction rate of 0.20 MPa / hour. After the hydrothermal treatment, the temperature was lowered to 70°C, and the crystallized product was recovered, and this was designated as the MFI zeolite of this example.

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

[0127] [Table 8]

[0128] The MFI zeolite of this example has an SiO2 / Al2O3 ratio of 1500, an average crystal size of 1.32 μm, an Na content (alkali metal content) of 0.5 mass %, and a BET specific surface area of 310 m 2 / g, the particle sizes were D10 1.15 μm, D50 1.99 μm, and D90 3.17 μm, with a standard deviation of 1.01 μm. 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 being stirred at 350 rpm. After the hydrothermal treatment, the temperature was lowered to 30°C, and the crystallized product was recovered and used as the MFI zeolite of this comparative example.

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

[0131] [Table 9]

[0132] The MFI zeolite of this comparative example had an SiO2 / Al2O3 ratio of 2500, an average crystal size of 1.22 μm, an Na content (alkali metal content) of 0.4 mass%, and a BET specific surface area of 360 m 2 / g, particle sizes were D10 2.49 μm, D50 37.1 μm, and D90 76.1 μm, 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 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, and then the temperature was lowered to 70°C. After the temperature was lowered, the composition was subjected to hydrothermal treatment at 70°C while reducing the pressure to 0.10 MPa (atmospheric pressure) at a pressure reduction rate of 0.20 MPa / hour, and the crystallized product was recovered and used as the MFI zeolite of this comparative example.

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

[0135] [Table 10]

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

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

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

[0139] The MFI zeolite of this comparative example was an MFI zeolite (crystalline aluminosilicate) consisting of a single phase of MFI structure, with a (020) / (101) peak ratio of 99% and a (101) / (501) peak ratio of 106%. It was confirmed that the crystallinity of the MFI zeolite of this comparative example was reduced by pulverization compared to the MFI zeolites of the examples. The XRD pattern of the zeolite of this comparative example is shown in the table below.

[0140] [Table 11]

[0141] The MFI zeolite of this comparative example had an SiO2 / Al2O3 ratio of 2500, an average crystal size of 0.96 μm, an Na content (alkali metal content) of 0.01 mass%, and a BET specific surface area of 320 m 2 / g, particle sizes were D10 0.52 μm, D50 0.88 μm, and D90 1.76 μm, 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 containing 6.0 mass% Al2O3 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 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, and then 3600 g of the raw material composition was filled into a 4 L sealed container and hydrothermally treated at 150°C and a pressure of 0.41 MPa for 36 hours while stirring at 350 rpm. Then, hydrothermally treated at 130°C while reducing the pressure to 0.27 MPa at a pressure reduction rate of 0.22 MPa / hour. After the hydrothermal treatment, the sealed container was cooled to 70°C, and the crystallized product was recovered, and this was designated as the MFI zeolite of this comparative example.

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

[0145] [Table 12]

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

[0147] Comparative Example 5 NBA, pure water, sodium hydroxide, and amorphous silicic acid containing 0.04% by mass of Al2O3 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 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, and 3600 g of the raw material composition was then filled into a 4 L sealed container and hydrothermally treated at 170°C under a pressure of 1.0 MPa for 36 hours while stirring at 350 rpm. After that, the hydrothermal treatment pressure was reduced to 0.27 MPa at a pressure reduction rate of 0.20 MPa / hour, and hydrothermally treated at 130°C. After the hydrothermal treatment, the temperature was lowered to 70°C, and the crystallized product was recovered, and this was used as the zeolite of this comparative example.

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

[0150] Measurement example 1 (viscosity measurement of zeolite slurry) The MFI zeolites of Example 1, Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 4 were each mixed with pure water to prepare 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 a shear rate of 1000 rpm was lower than that of the MFI zeolite of the comparative example. Therefore, it was confirmed that the MFI zeolite of the example has excellent handleability when made into a zeolite slurry without pulverization or the use of a dispersant, compared to the MFI zeolite of the comparative example.

[0153] Measurement example 2 (measurement of toluene adsorption amount) The toluene adsorption amounts of the MFI zeolites of Examples 1 to 5 and Comparative Example 3 were measured. The results are shown in the table below.

[0154] [Table 14]

[0155] From the above table, it was confirmed that the MFI zeolites of the Examples had a higher adsorption amount of toluene at each equilibrium pressure than the MFI zeolites of the Comparative Examples.

[0156] It was confirmed that the MFI zeolite of Comparative Example 3 had a (020) / (101) peak ratio of more than 95%, i.e., had a reduced crystallinity, and therefore the amount of toluene adsorbed decreased at each equilibrium pressure.

[0157] [Table 15]

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

Claims

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

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

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

4. 3. The MFI zeolite according to claim 1, 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. 3. The MFI zeolite according to claim 1, having an average crystal size of 0.1 μm or more and 5.0 μm or less.

6. BET specific surface area is 300m ２ The MFI zeolite according to claim 1 or 2, wherein the MFI zeolite has a molecular weight of 1 / g or more.

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