Method for producing faujasite-type zeolite with high packing density

Abstract

To provide FAU type zeolite in which the packing density is increased by making the shape of primary particles closer to a spherical shape, and to provide a method for producing the same.SOLUTION: The FAU type zeolite has a primary particle sphericity represented by the following formula (1) of 0.60 or more, and is produced by a method which includes, for example, a precursor preparation step of preparing an aqueous mixture solution containing a Si source, an Al source and seed crystals, and a hydrothermal treatment step of growing FAU type zeolite crystals by hydrothermal treatment of the aqueous mixture solution, and which uses slow-dissolving silica particles as the Si source of the aqueous mixed solution containing the seed crystals. Sphericity X=area A measured by image analysis / area B of perfect circle whose diameter is the major diameter measured by image machine analysis [1]SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a faujasite-type zeolite having a high packing density. Manufacturing method Regarding. [Background technology]

[0002] Zeolite is a general term for crystalline porous aluminosilicates. Zeolites have been widely used as catalysts, adsorbents, and separation membranes in many industrial processes, including oil refining and petrochemistry. For example, the fluid catalytic cracking process is an important process in which heavy oil in petroleum is cracked using a catalyst to obtain high-value-added fractions such as gasoline. Faujasite-type zeolites, which are porous materials with strong solid acidity, have long been used as catalysts for this process. Faujasite-type zeolites have also long been used as adsorbents.

[0003] In general, when zeolite is used as a catalyst or adsorbent, it is desirable to increase the packing density per unit volume and maximize the contact area per unit volume (Patent Document 1). As a method for solving this problem, a method is known in which primary particles of zeolite are aggregated to form spherical secondary particles (Patent Document 2). In this method, spherical secondary particles are formed by adding a binder component and spray drying. It is said that the packing density per unit volume can be increased by making the shape of the secondary particles spherical (Patent Document 1). This is because, while there are many gaps when irregular particles are packed, there are few unnecessary voids when spherical particles are packed, and the packing density can be increased due to excellent fluidity.

[0004] In this way, in the method of forming spherical secondary particles by spray drying, spherical secondary particles cannot be formed with zeolite alone, so a binder component is added, but there is a problem that the content of zeolite is reduced because components other than zeolite are included. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 59-137314 [Patent Document 2] Japanese Patent Application Publication No. 54-29898 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention Manufacturing method Faujasite-type zeolite (hereinafter referred to as FAU-type zeolite) is not a zeolite in which secondary particles are spherical as in the past, but rather a zeolite in which the shape of primary particles is made closer to a sphere to increase the packing density. The present invention provides a method for producing such FAU-type zeolite. [Means for solving the problem]

[0007] The present invention solves the above problems by the following configuration. The method for producing FAU zeolite includes a precursor preparation step of preparing an aqueous mixed solution containing a Si source, an Al source, and seed crystals, and a hydrothermal treatment step of hydrothermally treating the aqueous mixed solution to grow FAU zeolite crystals. 2 This production method is characterized by using silica particles having a particle size of less than 1 / g. Effect of the Invention

[0008] The present invention Manufacturing method Since FAU-type zeolite has many primary particles that are nearly spherical, it is possible to obtain a powder with a high zeolite content per unit volume. [Brief description of the drawings]

[0009] [Figure 1] Conceptual diagram of sphericity. [Diagram 2] Electron microscope photograph of the zeolite powder of Example 1. [Diagram 3] Electron microscope photograph of the zeolite powder of Comparative Example 1. [Figure 4] Electron microscope photograph of the zeolite powder of Comparative Example 2. [Diagram 5] Electron microscope photograph of the zeolite powder of Comparative Example 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [FAU type zeolite] The present invention Manufacturing method FAU type zeolite (Hereinafter referred to as the FAU type zeolite of the present invention) ) is an FAU-type zeolite whose primary particles have a sphericity of 0.60 or more as determined by image analysis, and whose shape is close to a sphere. FAU-type zeolite has a faujasite structure with Si, Al, and O as the basic framework elements, and this faujasite structure can be confirmed from the diffraction pattern obtained by X-ray diffraction measurement.

[0011] Conventional FAU zeolites have low packing density because they contain many octahedral or hexagonal plate-like primary particles with distinct crystal faces (Comparative Examples 1 and 4). In contrast, the FAU zeolite of the present invention contains many primary particles with high sphericity, and therefore has a higher packing density than conventional FAU zeolites. As shown in the following formula [1], when A is the area measured by image analysis of the zeolite primary particles and B is the area of ​​a perfect circle whose diameter is the major axis of the primary particles measured by image analysis, the sphericity is expressed by the ratio of the measured area A to the area B of the perfect circle. X = A / B [1] (In formula [1], X is sphericity, A is the area measured by image analysis, and B is the area of ​​a perfect circle whose major axis is the diameter measured by image analysis.) The concept of sphericity is shown in Figure 1. The closer the sphericity is to 1.0, the closer it is to a perfect sphere.

[0012] The sphericity of the primary particles of the FAU zeolite of the present invention is, on average, 0.60 or more, preferably 0.65 or more, and more preferably 0.70 or more. The FAU zeolite of the present invention has primary particles with a sphericity close to a sphere, and the sphericity of the primary particles is in the range of 0.60 to 1.0.

[0013] The primary particle diameter of the FAU zeolite of the present invention is preferably in the range of 0.1 μm to 10 μm, more preferably in the range of 0.5 μm to 5 μm, and particularly preferably in the range of 0.7 μm to 5 μm. When the primary particle diameter of the FAU zeolite of the present invention is in this range, the packing density becomes higher. This primary particle diameter can be measured by image analysis.

[0014] The properties of the FAU type zeolite of the present invention are greatly affected by the molar ratio of Si to Al (SiO2 / Al2O3 molar ratio: SAR). For example, an FAU type zeolite with a low SAR (high Al content) has a high solid acidity. In addition, the hydrothermal resistance is superior when the SAR is high (low Al content). The preferred SAR range varies depending on the application. For example, for detergent builder and moisture adsorbent applications, FAU type zeolite with a low SAR is preferred, more preferably an SAR of less than 5, and particularly preferably an X type zeolite with an SAR of less than 2. For VOC adsorbent applications, FAU type zeolite with an SAR of 30 or more is preferred, and more preferably an FAU type zeolite with an SAR of 50 or more. For catalyst applications, FAU type zeolite (Y type zeolite) with an SAR of 5 or more is preferred, and an SAR of 5 to 400 is more preferred, and an SAR of 5 to 200 is particularly preferred.

[0015] The FAU zeolite of the present invention has a cation exchange site and can be ion-exchanged with various cations. For example, it can be exchanged with various cations such as alkali metals such as Na and K, transition metals, rare earths, protons, and ammonium ions, and the properties of the FAU zeolite change depending on the cations exchanged. For example, if it is used as a detergent or adsorbent, it is preferable that it is ion-exchanged with alkali metals such as Na and K. In addition, when it is used for a catalyst application in a reaction that utilizes its solid acidity, it is preferable that it is ion-exchanged with protons, and it is more preferable that the content of alkali that inhibits the expression of the solid acidity is small, and specifically, it is preferable that it is 2 mass% or less in terms of M2O (M is an alkali metal), more preferably 1 mass% or less, and particularly preferably less than 0.5 mass%. In addition, since the packing density of the FAU zeolite also changes depending on the type of cation exchange site, when confirming the effect of the present invention, the cations of the cation exchange site were made the same in the examples and comparative examples.

[0016] The FAU zeolite of the present invention has a specific surface area of ​​600 m 2 / g or more. Zeolites generally have a very large specific surface area due to the pore structure derived from their skeleton. The FAU zeolite of the present invention has a specific surface area of ​​600 m 2 If the specific surface area is less than 900 m / g, the pore structure derived from the skeleton may not be sufficiently developed, and the solid acidity may be low. The higher the specific surface area of ​​the FAU zeolite, the better, but the upper limit is 900 m 2 More specifically, the specific surface area of ​​the FAU zeolite of the present invention may be 650 m 2 / g or more ~750m 2 / g or less.

[0017] The FAU zeolite of the present invention is processed into various forms depending on the application. When used as a detergent builder, it is used as it is in powder form, and when used as an adsorbent, it is molded into pellets or tablets together with a binder component and used. When used as a catalyst, it is molded into spheres, pellets, or tablets together with an active metal component, a cocatalyst component, a carrier component, a binder component, and the like and used. Specific examples of catalyst applications include use as a fluid catalytic cracking catalyst or hydrocracking catalyst in petroleum refining.

[0018] The FAU zeolite of the present invention has a high sphericality, so that the packing density can be increased. 3 Super~0.6g / cm 3 The following packing density can be obtained. FAU zeolite with a high packing density is excellent in terms of transportation costs because a large amount of FAU zeolite is packed per unit volume. In addition, since the FAU zeolite of the present invention does not contain a binder component, the amount of FAU zeolite per unit volume can be made larger than that of zeolite molded into spherical secondary particles by adding a binder component.

[0019] [Method for producing FAU type zeolite] The method for producing the FAU zeolite of the present invention will be specifically described below. The production method of the present invention is a production method for FAU type zeolite, and includes a precursor preparation step of preparing an aqueous mixed solution containing a Si source, an Al source, and FAU type zeolite seed crystals (hereinafter, sometimes simply referred to as seed crystals), and a hydrothermal treatment step of hydrothermally treating the aqueous mixed solution to grow FAU type zeolite crystals, characterized in that slowly soluble silica particles are used as the Si source of the aqueous mixed solution containing the seed crystals.

[0020] The aqueous mixture is prepared, for example, by adding slowly soluble silica particles, which are a Si source, and an Al source to a seed solution containing seed crystals. The slowly soluble silica particles are silica particles that dissolve slowly. For example, 2For example, silica particles with a specific surface area of ​​400 m 2 / g or more of fine silica powder is easily dissolved (easily soluble) and is not suitable as a Si source to be added to the seed solution.

[0021] FAU zeolite is a type of crystalline aluminosilicate with Si, Al, and O as basic skeletal elements, and a raw material containing Si (Si source) and a raw material containing Al (Al source) are used as raw materials. In the production method of the present invention, for example, an aqueous mixture is prepared by adding slowly soluble silica particles, which are a Si source, and an Al source to a seed solution containing the above-mentioned seed crystals, and the aqueous mixture is heat-treated to grow FAU zeolite crystals. It is known that FAU zeolite crystals grow by repeated dissolution and reprecipitation of Si and Al in an aqueous solution. In the production method of the present invention, the rate of dissolution and reprecipitation of Si and Al is slowed down by using slowly soluble silica particles as a Si source for growing the seed crystals, and primary particles having a shape close to a sphere, which is different from that of conventional FAU zeolites, are grown.

[0022] [Precursor preparation step] The production method of the present invention includes, for example, a precursor preparation step of preparing an aqueous mixture by adding slowly soluble silica particles, which are a Si source, and an Al source to a seed solution containing FAU-type zeolite seed crystals. The solution containing the seed crystals can be prepared by aging an aqueous solution having the following molar composition. In the production method of the present invention, the aqueous solution containing the seed crystals is called a seed solution. Na2O / Al2O3=5~32 SiO2 / Al2O3=5~30 H2O / Al2O3=100~2000

[0023] The Na source used in preparing the seed solution is NaOH, sodium silicate (water glass), sodium aluminate, etc. The Si source is silica sol, silica gel, alkoxysilane such as tetraalkoxysilane, water glass, etc. The Si source of this seed solution can be one that is easily dissolved (easily soluble). In terms of reactivity, water glass is preferred as this Si source. Note that water glass with a Na2O / SiO2 molar ratio of 1 to 3.5 is usually used. The Al source is alumina sol, alumina gel, sodium aluminate, aluminum sulfate, etc. Among these, sodium aluminate is preferred in terms of reactivity with silica and crystallization.

[0024] The Na2O / Al2O3 molar ratio after mixing the raw materials such as sodium aluminate, NaOH, and water glass is preferably in the range of 5 to 32, more preferably in the range of 8 to 24. When the Na2O / Al2O3 molar ratio is in this range, seed crystals are easily generated. The SiO2 / Al2O3 molar ratio after mixing the raw materials is preferably in the range of 5 to 30, more preferably in the range of 10 to 20. When the SiO2 / Al2O3 molar ratio is less than 5, crystals other than FAU zeolite, such as P-type zeolite and gmelinite, may be mixed in, and when the SiO2 / Al2O3 molar ratio exceeds 30, it may be difficult to obtain FAU zeolite crystals.

[0025] The H2O / Al2O3 molar ratio after mixing the above raw materials is preferably in the range of 100 to 2000, more preferably in the range of 150 to 1500. If the H2O / Al2O3 molar ratio is less than 100, primary particles having an irregular shape are likely to be obtained. If the H2O / Al2O3 molar ratio exceeds 2000, primary particles tend to be octahedral or hexagonal plate-like, and it is difficult to obtain spherical particles.

[0026] A seed solution is obtained by aging the aqueous solution in which the above-mentioned raw materials are mixed at 10 to 70° C., preferably 20 to 50° C. The aging time varies depending on the aging temperature, but is usually 1 to 200 hours.

[0027] To the seed solution, slowly soluble silica particles as a Si source, an Al source, and water are added to prepare an aqueous mixture. As the slowly soluble silica particles as a Si source, for example, 2 Silica particles with a specific surface area of ​​less than 1 / g are used. Silica particles with such a small specific surface area dissolve slowly (slow solubility), so the dissolution and reprecipitation of Si and Al in the next step proceeds slowly, resulting in primary particles that are nearly spherical (primary particles of FAU-type zeolite crystals). The above-mentioned compounds can be used as the Al source.

[0028] The molar composition of the aqueous mixture containing the Si source, Al source, and seed crystals is preferably in the following range: When the molar composition of the aqueous mixture is in this range, primary particles close to spheres are easily produced. Na2O / Al2O3=1~10 SiO2 / Al2O3=1~20 H2O / Al2O3=50~600

[0029] The Na2O / Al2O3 molar ratio of the aqueous mixture is preferably in the range of 1 to 10, more preferably in the range of 1 to 5. The SiO2 / Al2O3 molar ratio of the aqueous mixture is preferably in the range of 1 to 20, more preferably in the range of 1 to 10. Furthermore, the H2O / Al2O3 molar ratio of the aqueous mixture is preferably in the range of 50 to 600, more preferably in the range of 80 to 200. When the molar composition of the aqueous mixture is in these ranges, primary particles having a shape close to a sphere tend to grow.

[0030] As the precursor preparation step, a case has been shown in which an aqueous mixed solution is prepared by adding slowly soluble silica particles, which are a Si source, and an Al source to a seed solution containing FAU-type zeolite seed crystals, but the preparation of the aqueous mixed solution is not limited to the method of adding slowly soluble silica particles, which are a Si source, and an Al source to a seed solution containing seed crystals.

[0031] [Hydrothermal treatment process] In this step, the aqueous mixture obtained in the above-mentioned precursor preparation step is heat-treated to promote crystallization of the FAU-type zeolite.

[0032] The heat treatment may be performed by a conventional method such as a method of performing heat treatment under pressure using an autoclave or the like, a method of performing heat treatment under normal pressure, etc. In the production method of the present invention, the method of performing heat treatment under normal pressure is preferred from the viewpoint of slowing down the dissolution rate of the Si source.

[0033] The temperature for the heat treatment may be any temperature that promotes the crystallization of the FAU zeolite, and is preferably 50° C. to 100° C. When the heat treatment is performed under normal pressure, the temperature is more preferably 80° C. to 100° C. The heat treatment time depends on the heating temperature, but may be 2 to 200 hours.

[0034] [Other steps] The production method of the present invention can include a step of removing the solvent from the solution containing the FAU zeolite obtained in the crystallization step to separate the FAU zeolite. This can be easily carried out by a conventionally known method such as drying, centrifugation, or filtration.

[0035] The production method of the present invention may include a step of ion-exchanging FAU zeolite. Ion exchange can be easily performed by suspending FAU zeolite in an aqueous solution in which the cations to be exchanged are dissolved, and treating at an appropriate temperature for an appropriate time. Although it depends on the type of cation, the ion exchange temperature is preferably in the range of room temperature to 95°C, and the ion exchange time is preferably about 0.5 to 10 hours.

[0036] The production method of the present invention may include a dealumination step in order to increase the SiO2 / Al2O3 molar ratio of the FAU zeolite. The dealumination method may be a conventionally known method. For example, aluminum can be removed from the FAU zeolite by acid treatment, steam treatment, EDTA treatment, or other methods, and the SiO2 / Al2O3 molar ratio can be increased to about 200.

[0037] Examples of the present invention will be described below together with comparative examples. Note that the present invention is not limited to the following examples. In the examples and comparative examples, physical properties such as specific surface area and chemical composition were measured by the following methods.

[0038] [Specific surface area] The sample powder, which had been pretreated at 500°C for 1 hour under an inert gas atmosphere, was filled into a sample tube, and the specific surface area of ​​the sample powder was measured using a specific surface area measuring device ("MR-6" manufactured by Nippon Bell Co., Ltd.). Specifically, a mixed gas of nitrogen gas concentration 30 vol% and helium gas concentration 70 vol% was passed through a sample tube sufficiently cooled with liquid nitrogen to adsorb nitrogen to the sample powder, and the sample tube was then cooled to 25°C, and the amount of nitrogen desorbed from the sample powder was detected with a TCD detector. The amount of desorbed nitrogen was converted to specific surface area using the cross-sectional area of ​​the nitrogen molecule to calculate the specific surface area per gram of sample powder.

[0039] [Composition analysis] The contents of Si, Al and alkali in the sample powder were measured using a fluorescent X-ray analyzer (RIX-3000). From the measurement results, the contents of Si and Al were converted into the molar amounts of SiO2 and Al2O3, respectively, and the SiO2 / Al2O3 molar ratio was calculated.

[0040] [Ignition loss] The ignition loss was calculated from the weight loss observed when the sample powder was heated at 1000°C for 1 hour using the following formula. Ignition loss (%) = [(weight of sample powder before heating (g) - weight of sample powder after heating (g)] / weight of sample powder before heating (g)

[0041] [Sphericity of primary particles] After dispersing the sample powder on a sample plate, the shape of the primary particles was observed using a scanning electron microscope (JSM-7600S manufactured by JEOL Ltd.) (accelerating voltage 1.0 kV, magnification 10,000 to 50,000 times). 50 primary particles were randomly selected from the obtained image, and the area of ​​the primary particles measured by image analysis was taken as A, the area of ​​a perfect circle with the major axis of the primary particles measured by image analysis as the diameter was taken as B, and the sphericity X was calculated using the following formula [1]. The primary particle diameter was taken as the average value of the major axes. Sphericity of primary particles (X) = A / B [1]

[0042] [Filling density] The sample powder was filled into a 200 ml graduated cylinder up to the 100 ml mark, and then tapped up and down 100 times from a height of about 1 cm. The weight of the sample powder filled into the graduated cylinder was T (g), and the volume after tapping was V1 (cm 3 ) and the packing density (ρ) was calculated using the following formula [2]. Packing density (ρ)=T / V1 ···[2]

[0043] [X-ray diffraction measurement] The sample powder was ground in a mortar and set on a sample plate. X-ray diffraction measurements were performed under the following conditions, and the presence or absence of the faujasite structure was confirmed from the obtained XRD pattern. Equipment: Rigaku MiniFlex Operation axis: 2θ / θ Source:CuKα Measurement method: Continuous Voltage: 40kV Current: 15mA Starting angle: 2θ=5° End angle: 2θ=50° Sampling width: 0.020° Scan speed: 10.000[° / min] <Judgment criteria> When the X-ray diffraction pattern obtained by the above measurement has all the peaks attributable to the Miller indices of the faujasite structure, it is judged that the faujasite structure is present. Note that the peak positions of each peak may include an error of about 2θ=±0.2°.

[0044] Example 1 <Precursor preparation process> 0.29 kg of a sodium aluminate aqueous solution with a Na content (Na2O equivalent) of 17% by mass and an Al content (Al2O3 equivalent) of 22% by mass was prepared. This sodium aluminate aqueous solution was added to 2.4 kg of a 21.7% by mass sodium hydroxide aqueous solution. While stirring this solution, 2.3 kg of No. 3 water glass with a Si concentration (SiO2 equivalent) of 24% by mass was added, stirred for 1 hour, and then allowed to stand at 30°C for 12 hours to prepare a seed solution. The molar composition of the seed solution was 16Na2O:Al2O3:15SiO2:330H2O.

[0045] As the silicon source, 18 kg of No. 3 water glass with a silicon concentration (SiO2 equivalent) of 24 mass% and slowly soluble silica particles (fused silica UFP-30 manufactured by Denka Co., Ltd., specific surface area 37 m 2 4.5 kg of SiO2 / g was mixed with 16.8 kg of water. 2.5 kg of the seed solution was added to this solution, and then 8.1 kg of sodium aluminate with a Na content (Na2O equivalent) of 7.7 mass% and an Al content (Al2O3 equivalent) of 22 mass% was added as an Al source to prepare an aqueous mixture. The molar composition of this aqueous mixture was 2.8Na2O:Al2O3:8.6SiO2:113H2O.

[0046] <Hydrothermal treatment process> The aqueous mixture was aged for 3 hours at room temperature, and then heat-treated at 95°C for 35 hours to grow zeolite crystals. The zeolite crystals were then filtered off, washed with water, and dried at 130°C for 20 hours. The obtained zeolite crystals were confirmed to have a faujasite structure by X-ray diffraction measurement. The above-mentioned measurements were also carried out. The results are shown in Table 1. An electron microscope photograph of this FAU-type zeolite is shown in Figure 2.

[0047] Example 2 5 kg of the FAU zeolite obtained in Example 1 was added to 50 L of water at 60°C, and 1.4 kg of ammonium sulfate was further added to prepare a suspension. After stirring this suspension at 70°C for 1 hour, the FAU zeolite was filtered off. This FAU zeolite was washed with water, then washed with an ammonium sulfate solution in which 1.4 kg of ammonium sulfate was dissolved in 50 L of water at 60°C, and further washed with 50 L of water at 60°C. The washed FAU zeolite was dried at 130°C for 20 hours to obtain FAU zeolite ion-exchanged with ammonium ions. The above-mentioned measurements were performed on this FAU zeolite. The results are shown in Table 1.

[0048] Example 3 The FAU zeolite obtained in Example 2 was calcined at 670°C for 1 hour in a saturated steam atmosphere to perform the first steam treatment. 4.0 kg of this FAU zeolite was added to 400 L of water at 60°C, and then 5.6 kg of ammonium sulfate was added to prepare a suspension. This suspension was stirred at 90°C for 1 hour, and then the FAU zeolite was filtered out. This was washed with 240 L of water at 60°C and dried at 110°C for 20 hours to obtain FAU zeolite crystals with an increased SiO2 / Al2O3 molar ratio. Furthermore, this FAU zeolite crystal was calcined at 630°C for 2 hours in a saturated steam atmosphere to perform the second steam treatment. 1.0 kg of this FAU zeolite crystals was added to 15 L of water at room temperature, and 1.4 kg of 25% by mass sulfuric acid was gradually added. After the entire amount of sulfuric acid was added, the temperature was raised to 75°C and stirred for 4 hours, and the FAU zeolite was filtered and washed with 60 L of ion-exchanged water. The washed FAU zeolite was dried at 110°C for 20 hours to obtain FAU zeolite crystals with a further increased SiO2 / Al2O3 molar ratio. The above-mentioned measurements were carried out on this FAU zeolite crystal. The results are shown in Table 1.

[0049] [Comparative Example 1: Commercially available FAU-type zeolite] A commercially available FAU type zeolite (CBV100 manufactured by Zeolyst Co., Ltd.) was used. The above-mentioned measurements were carried out on this FAU type zeolite. The results are shown in Table 1. An electron microscope photograph of this FAU type zeolite is shown in FIG.

[0050] [Comparative Example 2: Use of easily soluble silica particles] FAU-type zeolite was produced in the same manner as in Example 1, except that, as the Si source to be added to the seed solution, easily soluble silica particles were used instead of the slowly soluble silica. TM 380, specific surface area 405m 2 / g) was used. The above-mentioned measurements were carried out on this FAU type zeolite. The results are shown in Table 1. An electron microscope photograph of this FAU type zeolite is shown in FIG.

[0051] [Comparative Example 3: Silica particles not added to the raw material solution] 35 kg of No. 3 water glass with a Si concentration (SiO2 equivalent) of 24 mass% was slowly added to 7.4 kg of an aluminum sulfate aqueous solution with a H2SO4 concentration of 20.3 mass% and an Al concentration (Al2O3 equivalent) of 7.0 mass%, and then 5.3 kg of sodium aluminate with a Na content (Na2O equivalent) of 7.7 mass% and an Al content (Al2O3 equivalent) of 22 mass% was added and stirred for 10 minutes to prepare a raw material solution. 2.4 kg of the seed solution obtained by the method of Example 1 was added to this raw material solution, and the mixture was stirred and mixed until it became uniform to prepare an aqueous mixture. The molar composition of this aqueous mixture was 2.8Na2O:Al2O3:8.6SiO2:113H2O. The subsequent steps were performed in the same manner as in Example 1 to prepare FAU type zeolite. The above-mentioned measurements were performed on this FAU type zeolite. The results are shown in Table 1. An electron microscope photograph of this FAU type zeolite is also shown in FIG. 5.

[0052] [Comparative Example 4: Commercially available FAU-type zeolite] A commercially available FAU type zeolite (CBV712 manufactured by Zeolyst Co., Ltd.) was used. The above-mentioned measurements were carried out on this FAU type zeolite. The results are shown in Table 1.

[0053] [Table 1]

[0054] Slowly soluble silica particles (specific surface area 37 m) were used as the Si source to be added to the seed solution. 2 In the FAU zeolite of Example 1 prepared using silica particles having a specific surface area of ​​405 m / g, the primary particles are mostly rounded (FIG. 2), and the sphericity is 0.75. 2 The primary particles of the FAU zeolite of Comparative Example 2, which was prepared using 100% silica particles (0.1 μm / g), were mostly octahedral in shape, and some of them were hexagonal plate-shaped primary particles (FIG. 4). The FAU zeolite of Comparative Example 3, which was prepared without using silica particles as the Si source added to the seed solution, had many hexagonal plate-shaped primary particles, and some of them were octahedral in shape (FIG. 5). The commercially available FAU zeolite of Comparative Example 1 also contained primary particles with a shape similar to that of the FAU zeolite of Comparative Example 3 (FIG. 3). In this way, it was confirmed that the FAU zeolite of the present invention had a higher sphericity and was closer to a sphere than the primary particles of conventional FAU zeolite.

[0055] Since the packing density of FAU zeolite is considered to be affected by its SiO2 / Al2O3 molar ratio, the type of cation, and the water content, the packing densities were compared using zeolites prepared so that these were approximately the same. The FAU zeolite of Example 1, in which the sphericity of the primary particles is 0.60 or more, has a packing density 10% or higher than that of the FAU zeolites of Comparative Examples 1 and 2, in which the sphericity is less than 0.60. Similarly, the packing density of the FAU zeolites of Example 2 and Comparative Example 3 is 10% or higher. Furthermore, the same is true for Example 3 and Comparative Example 4.

Claims

[Claim 1] A method for producing FAU type zeolite, comprising: a precursor preparation step of preparing an aqueous mixed solution containing a Si source, an Al source, and seed crystals; and a hydrothermal treatment step of hydrothermally treating the aqueous mixed solution to grow FAU type zeolite crystals, the method being characterized in that silica particles having a specific surface area of ​​100 m2 / g or less are used as the Si source of the aqueous mixed solution containing the seed crystals.

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