MFI-type zeolite aggregate and method for producing same

Abstract

[Problem] To provide zeolite having high adsorption capacity and excellent handling properties. [Solution] This MFI-type zeolite aggregate is an aggregate in which MFI-type zeolite particles serving as primary particles are aggregated. The molar ratio (SiO2 / Al2O3) of silica to alumina is greater than 40. The ratio (B / A) of the pore diameter peak top (B) measured by a mercury intrusion technique to the primary particle diameter (A) measured by an electron microscope is 0.9 or more.

Description

MFI-type zeolite aggregate and method for producing the same

[0001] The present invention relates to an MFI-type zeolite aggregate aggregated under normal pressure and a method for producing the same.

[0002] Zeolite is a general term for crystalline aluminosilicates having micropores. Specifically, it refers to a group of crystalline substances where a part of Si is replaced by Al, having a framework consisting of a three-dimensional network of Si-O bonds and micropores derived from the framework structure. MFI-type zeolite (ZSM-5) is a type of synthetically obtained zeolite, and it is a high-silica zeolite having a large molar ratio of silica to alumina (SiO ２ / Al ２ O ３ ). MFI-type zeolite is widely used as catalysts in the petrochemical industry, adsorbents for volatile organic compounds (VOC), etc.

[0003] In general, for the synthesis of zeolite, a mixture of a silica source (such as sodium silicate, colloidal silica, fumed silica, or silicon alkoxide), an alumina source (such as sodium aluminate, aluminum hydroxide, aluminum nitrate, or aluminum alkoxide), a mineralizer (alkali metal hydroxide or fluoride), and water is subjected to hydrothermal treatment under high temperature and high pressure. The reaction proceeds from an amorphous precursor (hydrogel), nucleation and crystal growth occur, and a porous silicate framework is formed.

[0004] Patent Document 1 discloses a method for producing ZSM-5-based (MFI-type) zeolite. The production method comprises the steps of: heating a mixture containing a silica source, an alumina source, a neutralizing agent, and crystalline ZSM-5 nuclei to prepare a first solution in a solution state; mixing the first solution with a second solution containing a salt including sodium sulfate (Na ２ SO ４ ), sodium nitrate (NaNO ３ ), trisodium phosphate (Na ３ PO ４ ), or a combination thereof to prepare a reaction mother liquor; and continuously supplying the reaction mother liquor to a hydrothermal synthesis reactor for continuous crystallization, wherein [Formula 1] 0.20 ≤ W ａ / Wｂ ≦0.40 (in formula 1, W ａ This is the salt content in the reaction mother liquor, W ｂ This is the silica content in the reaction mother liquor.

[0005] In the manufacturing method described in Patent Document 1, ZSM-5 zeolite is produced by continuous synthesis rather than batch synthesis (Patent Document 1, paragraph 0008, etc.). ２ SO ４ NaNO ３ Na ３ PO ４ By mixing salts such as these, the viscosity of the reaction mother liquor is reduced, enabling continuous synthesis (Patent Document 1, paragraph 0111 and Table 1). In other words, the mixing of these salts is to reduce viscosity and enable continuous synthesis, and does not involve the formation of zeolite aggregates. Furthermore, in the manufacturing method of Patent Document 1, an autoclave reactor heated to 150°C (Patent Document 1, paragraph 0069) is used in the step of continuously crystallizing the reaction mother liquor, so the synthesis equipment becomes expensive and the manufacturing cost increases. Moreover, because no template is used, the molar ratio of silica to alumina in the synthesizable zeolite is at most about 40.

[0006] On the other hand, unlike the manufacturing method described in Patent Document 1, zeolite synthesis at atmospheric pressure is also known. For example, Patent Document 2 discloses a crystallization reaction step in which a mixed gel is used to produce MFI-type zeolite under atmospheric pressure (Patent Document 2, claim 4, etc.). This allows for the synthesis of zeolite at atmospheric pressure using a simple and inexpensive stainless steel (SUS) reaction vessel, without the need for a sealed, heat-resistant, and pressure-resistant vessel such as an autoclave. However, atmospheric pressure synthesis at a reaction temperature of 100°C or lower has the disadvantage that only zeolite with small particle sizes, such as 1 μm or less, can be obtained.

[0007] In the case of small particle size zeolite, the manufacturing process requires the use of filter media with a mesh so fine that the zeolite cannot pass through, resulting in prolonged filtration. Separation time is also long when using a centrifuge for washing and solid-liquid separation. Consequently, it is not possible to improve the mass production capacity of zeolite. Furthermore, the dried zeolite powder with small particle size has poor fluidity and separability, and the particles adhere to each other. This causes bridging, where the powder accumulates in an arch shape, blocking the outlet of feeders and causing pipe blockage during manufacturing and use. In short, zeolite powder with small particle size has poor handling properties.

[0008] Japanese Patent Publication No. 7116194 Japanese Patent Publication No. 7113697

[0009] Therefore, the present invention aims to provide an MFI-type zeolite aggregate that can be synthesized at atmospheric pressure and a method for producing the same. Furthermore, it aims to provide an MFI-type zeolite aggregate that combines the characteristics of both small-particle and large-particle zeolites and a method for producing the same.

[0010] The MFI-type zeolite aggregate according to the present invention is an aggregate formed by the aggregation of MFI-type zeolite particles, which are primary particles, wherein the molar ratio of silica to alumina (SiO₂ ２ / Al ２ O ３ The ratio of the peak top of the pore diameter (B) measured by mercury intrusion to the primary particle diameter (A) measured by electron microscopy (B / A) is 0.9 or greater.

[0011] Firstly, the MFI-type zeolite aggregate of the present invention has the characteristics of a small-particle zeolite. That is, because a large number of primary particles of MFI-type zeolite are aggregated rather than bound to each other, the contact area is large, improving adsorption performance (adsorption amount and adsorption rate), and it functions as an excellent adsorbent for volatile organic compounds (VOCs), for example. Furthermore, when the MFI-type zeolite aggregate of the present invention is used as a catalyst, the diffusivity of the reaction substrate and product is good, and the dispersion of the supported metal is improved. Moreover, the MFI-type zeolite aggregate of the present invention has high resistance to catalyst sintering, which is caused by exposure to high temperatures and a decrease in surface area, and to the precipitation of coke (by-product) that covers active sites and clogs pores.

[0012] Secondly, the present invention possesses not only the characteristics of small-particle zeolites but also the characteristics of large-particle zeolites. Specifically, it has high filtration performance due to the formation of voids between particles and aggregates, good separation between particles and aggregates, suppression of bridging and pipe blockage, and excellent handling properties.

[0013] Thirdly, the present invention also possesses the characteristics of aggregated particles. That is, because it has voids inside the aggregate, it has high oil absorption capacity and moisture retention capacity. For this reason, moisture content is easy to adjust and molding is easy. Thus, the MFI-type zeolite aggregate of the present invention combines the characteristics of small-particle and large-particle zeolites and their aggregates.

[0014] In embodiments of the MFI-type zeolite aggregate of the present invention, the ratio of the peak top of the pore diameter (B) measured by mercury intrusion to the primary particle diameter (A) measured by electron microscopy (B / A) is 1.0 to 5.0. The molar ratio of silica to alumina (SiO ２ / Al ２ O ３ The ratio is 50 or more. The amount of o-xylene adsorbed is 2.0 to 10% by weight.

[0015] The present invention relates to a method for producing MFI-type zeolite aggregates, comprising the steps of: aging a raw material mixture containing a solid silica source, a template, an alkali metal salt, and an alkaline solution to obtain an aged mixture; adding seed crystals to the aged mixture; crystallizing the aged mixture under normal pressure while adding the seed crystals or after adding the seed crystals to produce aggregated MFI-type zeolite particles; and calcining the aggregated MFI-type zeolite particles to remove the template and obtain an MFI-type zeolite aggregate. The obtained MFI-type zeolite aggregate has a molar ratio of silica to alumina (SiO₂ ２ / Al ２ O ３ The ratio of the peak top of the pore diameter (B) measured by mercury intrusion to the primary particle diameter (A) measured by electron microscopy (B / A) is 0.9 or greater.

[0016] In this invention, large particles can be obtained by agglomerating single particles of MFI-type zeolite of 1 μm or less before or during crystallization. Furthermore, in this invention, MFI-type zeolite aggregates can be obtained by synthesis under normal pressure and at a temperature of 100°C or less, rather than under high pressure.

[0017] In embodiments of the manufacturing method of the present invention, the step of producing aggregated MFI-type zeolite particles is carried out at a temperature of 60 to 99°C during the crystallization reaction. The alkali metal of the alkali metal salt is one or more selected from sodium, potassium, or lithium. The salt of the alkali metal salt is one or more selected from chloride salts, nitrates, sulfates, or carbonates. In the raw material mixture, the molar ratio of the alkali metal (X) chloride salt or sulfate to silica is (XCl / SiO ２ or X ２ SO ４ / SiO ２ The molar ratio of sodium oxide derived from the alkaline solution to silica (Na) is 0.05 or higher. ２ O / SiO ２ The ratio is 0.03 to 0.10. The raw material mixture further contains an alumina source. The amount of seed crystal added is SiO in the raw material mixture. ２ It is 0.05 to 5% by weight relative to the total amount.

[0018] The present invention combines the characteristics of small-particle zeolites, such as a large contact area and high adsorption performance, with the characteristics of large-particle zeolites, such as excellent filtration and handling performance. Furthermore, the voids within the aggregates result in high oil absorption and water retention capacity, and facilitate molding. Therefore, the MFI-type zeolite aggregates of the present invention are suitable for use as adsorbents and catalysts, and because they have excellent filtration and handling performance, the productivity of MFI-type zeolite aggregates can be improved.

[0019] SEM image showing MFI-type zeolite aggregates according to the present invention SEM image showing MFI-type zeolite particles (primary particles) Graph showing pore distribution of Examples 1 to 10 measured by mercury porosimometer Graph showing pore distribution of Examples 11 to 13 measured by mercury porosimometer Graph showing pore distribution of comparative example measured by mercury porosimometer Graph showing toluene adsorption amount

[0020] Embodiments of the MFI-type zeolite aggregate and its manufacturing method according to the present invention will be described below. The embodiments described below are illustrative and should not be interpreted as limiting the present invention. The MFI-type zeolite aggregate according to the present invention is an aggregate (assembly) formed by the aggregation of a large number of primary particles (single particles) of MFI-type zeolite. ZSM-5, ZSM-8, TS-1, etc. can be used as the primary particles of MFI-type zeolite, but ZSM-5 is particularly preferred. Two or more types of the above-mentioned MFI-type zeolite may be mixed and used.

[0021] Figure 1 shows an image (SEM magnification 10,000x) of an MFI-type zeolite aggregate according to an embodiment of the present invention, taken with a scanning electron microscope. The MFI-type zeolite aggregate is formed when a large number of MFI-type zeolite particles, approximately 1 μm or less in size, gather together to form aggregates as secondary particles, such as clumps or clusters, and has voids between the particles and between the aggregates, which appear black in the SEM image of Figure 1.

[0022] Figure 2 shows an image (SEM magnification 10,000x) of MFI-type zeolite particles, which are the raw material for the MFI-type zeolite aggregates shown in Figure 1, taken with a scanning electron microscope. The MFI-type zeolite particles shown in Figure 2 are the raw material used for the MFI-type zeolite aggregates shown in Figure 1, and Figure 2 was taken at the same magnification as Figure 1. Comparing Figure 1 and Figure 2, there is no significant difference in the size of the primary particles, but the void dimensions of the MFI-type zeolite aggregates of the present invention shown in Figure 1 are clearly larger than those of the MFI-type zeolite particles shown in Figure 2. As a result, the present invention offers high filtration performance, improved productivity of MFI-type zeolite aggregates, and good handling.

[0023] In this invention, the molar ratio of silica to alumina (hereinafter referred to as the "silica / alumina ratio") (SiO ２ / Al２ O ３ ) is greater than 40, preferably 50 or more, 70 or more, or 80 or more, and more preferably 100 or more. There is no particular upper limit, but it is preferably 8000 or less or less, and more preferably 7000 or less or 6200 or less.

[0024] The ratio of the peak top of the pore diameter (B) measured by the mercury intrusion method to the primary particle diameter (A) measured by an electron microscope (hereinafter referred to as the "aggregation index") (B / A) is 0.9 to 5.0, preferably 1.0 to 3.0, and more preferably 1.1 to 2.5. If the aggregation index (B / A) is less than 0.9, it is the value shown for zeolite that has not aggregated (as shown in Comparative Examples 1 to 4 below), and it cannot possess the characteristics of both small and large particles. On the other hand, if it exceeds 5.0, the aggregation becomes brittle and it is more likely to break down into single particles, resulting in poor handling properties.

[0025] The method for producing the MFI-type zeolite aggregate of the present invention will be described in detail below.

[0026] First, a raw material mixture is obtained by mixing a solid silica source, a template, an alkali metal salt, and an alkaline solution as raw materials. The solid silica source is a conventionally known SiO used in the production of various zeolites. ２ The included materials can be, for example, tetraethyl orthosilicate, colloidal silica, silica gel, silica hydrogel, etc.

[0027] A template (also called a "template molecule" or "organic structure-determining agent (OSDA)") is a structure-determining agent that forms the 10-membered ring pores characteristic of MFI-type zeolites. For example, quaternary ammonium salts such as tetrapropylammonium bromide (TPABr), tetrapropylammonium chloride (TPACl), and tetrapropylammonium hydroxide (TPAOH), and amines such as triethylamine (TEA) can be used as templates.

[0028] The alkali metal in the alkali metal salt is one or more selected from sodium (Na), potassium (K), or lithium (Li). The salt in the alkali metal salt is one or more selected from chloride salts, nitrates, sulfates, or carbonates. It is believed that aggregation of MFI-type zeolites will occur with any of the above combinations of alkali metal salts.

[0029] The phenomena of particle dispersion and aggregation in a liquid are determined by the sum of electrostatic repulsion and van der Waals forces acting between particles due to the overlap of the electric double layer (DLVO theory). As the interparticle distance decreases, a barrier is reached where the repulsive force is maximum, and as the interparticle distance decreases further, a primary minimum (deep valley) is reached where the attractive force is maximum. High energy is required to overcome this barrier, and once the barrier is overcome and the primary minimum with maximum attractive force is reached, irreversible aggregation occurs, making redispersion difficult. In this invention, it is believed that MFI-type zeolite aggregates are formed by this phenomenon. That is, when an alkali metal salt is added as a raw material, the interparticles easily approach each other, overcoming the barrier where the repulsive force is maximum, and reach the primary minimum with maximum attractive force. As a result, in this invention, MFI-type zeolite particles strongly attract each other and aggregate, forming irreversible aggregates that are difficult to separate.

[0030] In the raw material mixture, the molar ratio of alkali metal (X) chloride or sulfate to silica is (XCl / SiO2). ２ or X ２ SO ４ / SiO ２ ) is 0.05 or higher, preferably 0.1 or higher (as shown in the examples in Table 2 below). XCl / SiO ２ or X ２ SO ４ / SiO ２ However, if the amount is less than 0.05, the amount of chloride salt is too small, and as mentioned above, it is not possible to overcome the barrier of maximum repulsion, and aggregation of MFI-type zeolite particles hardly occurs. Also, if the amount of chloride salt is too small, the primary particle size of the MFI-type zeolite becomes small, and the filtration performance during zeolite production is extremely reduced. XCl / SiO ２ or X ２ SO ４ / SiO ２There are no particular restrictions on the upper limit, but it should be 1 or less, preferably 0.5 or less, and more preferably 0.3 or less.

[0031] The alkaline solution is not particularly limited, but one or more of the following can be used as the alkaline solution: aqueous sodium hydroxide solution, aqueous potassium hydroxide solution, aqueous sodium bicarbonate solution, aqueous potassium bicarbonate solution, aqueous sodium dihydrogen carbonate solution, aqueous potassium dihydrogen carbonate solution, etc.

[0032] In the raw material mixture, the molar ratio of sodium oxide derived from the alkaline solution to silica (Na ２ O / SiO ２ The amount of sodium is 0.01 to 0.30, preferably 0.03 to 0.10. The more alkaline solution is added, the shorter the crystallization reaction time (time required for crystallization), but Na ２ O / SiO ２ When the value exceeds 0.30, the zeolite redissolves, causing the aggregate to break down and the filtration performance to deteriorate. In addition, a large amount of hydrophilic alkali metals may remain in the resulting MFI-type zeolite aggregates, potentially impairing their physical properties.

[0033] The raw material mixture may further contain an alumina source. Aluminum sulfate, basic aluminum sulfate, sodium aluminate, etc., can be used as the alumina source, but sodium aluminate is particularly preferred. The silica source and the alumina source are composed of SiO2. ２ / Al ２ O ３ The mixture is prepared so that the molar ratio is a predetermined ratio. However, when producing MFI-type zeolite containing a particularly large amount of Si (for example, with a molar ratio of 1000 or more), the use of an alumina source can be omitted.

[0034] Next, the raw material mixture is heated to 60-95°C (aging temperature) and aged for several hours to obtain an aged mixture. The resulting aged mixture contains a homogeneous silica-alumina mixed gel. Aging is generally carried out below the reaction temperature. Aging prevents the formation of impurities and increases the crystallization reaction rate.

[0035] After maturation, seed crystals are added to the matured mixture. The addition of seed crystals eliminates the nucleation process and shortens the crystallization reaction time. It also prevents the decomposition and denaturation of the template during the reaction, allowing for the formation of a less strained MFI-type zeolite skeletal structure, resulting in a larger specific surface area and pore volume. Conventional MFI-type zeolites can be used as seed crystals, preferably those whose templates have been removed and whose pores defined by calcination or other methods. This allows for the synthesis of MFI-type zeolites with less strain and a uniformly distributed pore structure. Seed crystals that have been moderately pulverized, for example, by dry grinding or wet grinding, are preferable because they disperse well after addition.

[0036] The amount of seed crystal added is SiO in the raw material mixture. ２ The amount is 0.01 to 10% by weight, preferably 0.05 to 5% by weight (as shown in the examples in Table 2 below). If it is less than 0.01%, the reaction proceeds slowly and productivity deteriorates. If it is 10% by weight, the preparation of seed crystals becomes complicated and productivity deteriorates.

[0037] While adding seed crystals or after adding seed crystals, the aged mixture is heated and maintained at a temperature above the aging temperature, and a crystallization reaction is carried out under atmospheric pressure. This causes crystal growth to proceed with the seed crystals as nuclei, and aggregated MFI-type zeolite particles are obtained. In this invention, particle aggregation occurs because alkali metal salts are contained, which is presumed to be because the seed crystals aggregate first, and then crystallization proceeds to form MFI-type zeolite particles. In this embodiment, the crystallization reaction is carried out at atmospheric pressure, i.e., in an open system, without using a heat-resistant and pressure-resistant container. The crystallization reaction temperature is set to 60 to 99°C. Below 60°C, sufficient crystallization will not occur, and the desired MFI-type zeolite cannot be obtained. Above 99°C, the template and seed crystals may flow, and the pore distribution may become non-uniform. The crystallization reaction time is approximately 8 to 120 hours.

[0038] After the crystallization reaction is complete, the aggregated MFI-type zeolite particles are filtered and washed as appropriate to remove impurities such as alkali metals, and then dried. After drying, they are calcined to remove the template and obtain the MFI-type zeolite aggregate according to the present invention. Removal of the template defines the 10-membered ring-shaped pores characteristic of MFI-type zeolite. The calcination temperature is approximately 400 to 700°C, at which the template decomposes but the zeolite crystals are not damaged. The calcination time is approximately 30 minutes to 20 hours.

[0039] The resulting MFI-type zeolite aggregates have a silica / alumina ratio greater than 40 or 50 or higher, and an aggregation index (B / A) of 0.9 or higher. Furthermore, the MFI-type zeolite aggregates are pulverized to an appropriate size depending on the application.

[0040] The following will explain the examples (the present invention) and comparative examples (prior art) in comparison.

[0041] [MFI-type zeolite aggregate of the present invention] (Example 1) Silica (Mizukasil P-78F SiO2, manufactured by Mizusawa Chemical Industries) as a solid silica source ２ : 90.2%, H ２ 182.9 g of O: 9.8%, 73.1 g of tetrapropylammonium bromide (TPABr) 50% aqueous solution (SACHEM Zeogen360) as a template, 24.1 g of sodium chloride (Nihon Kaiyo Shiroshio M) as an alkali metal salt, and 49% caustic soda solution (Na) as an alkaline solution. ２ O: 37%, H ２16.3 g of O:63% and 1314 g of water were mixed to obtain a raw material mixture. Next, the raw material mixture was aged at approximately 95°C for approximately 3 hours to obtain a matured mixture. Furthermore, 8.4 g of 0.4 μm MFI-type zeolite (19.7% slurry) was added as seed crystals to the matured mixture, and the matured mixture was subjected to a crystallization reaction in a stainless steel reaction vessel at approximately 95°C under atmospheric pressure for approximately 17 hours with a stirring speed of 250 rpm to obtain aggregated MFI-type zeolite particles. The obtained MFI-type zeolite aggregates were filtered and washed, dried at approximately 150°C, and then calcined at approximately 550°C for approximately 2 hours. After calcination, the aggregates were pulverized at 12000 rpm using a 1 mm screen with a fine grinder (Dalton Lab Mill LM-05) to produce the MFI-type zeolite aggregates of Example 1 according to the present invention (Figure 1 SEM image).

[0042] (Example 2) An MFI-type zeolite aggregate of Example 2 according to the present invention was produced by the same method as in Example 1, except that the amount of salt was 16.1 g.

[0043] (Example 3) An MFI-type zeolite aggregate of Example 3 according to the present invention was produced by the same method as in Example 1, except that 180.6 g of silica, 72.2 g of TPABr, 39.6 g of sodium chloride, 16.1 g of caustic soda, 1272 g of water, and 40.8 g of seed crystals were used.

[0044] (Example 4) An MFI-type zeolite aggregate of Example 4 according to the present invention was produced by the same method as in Example 1, except that 180.6 g of silica, 72.2 g of TPABr, 39.6 g of sodium chloride, 16.1 g of caustic soda, 1301 g of water, and 4.1 g of seed crystals were used.

[0045] (Example 5) An MFI-type zeolite aggregate of Example 5 according to the present invention was produced by the same method as in Example 1, except that 160.7 g of silica, 64.3 g of TPABr, 35.3 g of sodium chloride, 14.3 g of caustic soda, 1328 g of water, and 7.6 g of seed crystals were used.

[0046] (Example 6) An MFI-type zeolite aggregate of Example 6 according to the present invention was produced in the same manner as in Example 1, except that 30.7 g of potassium chloride (industrial potassium chloride manufactured by Takasugi Pharmaceutical Co., Ltd.) was mixed in place of sodium chloride.

[0047] (Example 7) Using 12.9 g of caustic soda and 1312 g of water, further adding sodium aluminate (Al ２ O ３ : 23%, Na ２ O: 19.2%, H ２ Except for adding 6.6 g of O: 57.8%, the MFI-type zeolite aggregate of Example 7 according to the present invention was produced by the same method as in Example 1.

[0048] (Example 8) An MFI-type zeolite aggregate of Example 8 according to the present invention was produced in the same manner as in Example 1, except that 12.1 g of caustic soda and 1310 g of water were used, and 11.3 g of sodium aluminate was added.

[0049] (Example 9) An MFI-type zeolite aggregate of Example 9 according to the present invention was produced by the same method as in Example 1, except that 16.5 g of caustic soda and 1307 g of water were used, and 12.5 g of sodium aluminate was added.

[0050] (Example 10) An MFI-type zeolite aggregate of Example 10 according to the present invention was produced in the same manner as in Example 1, except that 21.1 g of caustic soda and 1304 g of water were used, and 12.5 g of sodium aluminate was added.

[0051] (Example 11) Instead of table salt, sodium sulfate (Na ２ SO ４ Except for mixing 58.5 g of the above, the MFI-type zeolite aggregate of Example 11 according to the present invention was produced in the same manner as in Example 1.

[0052] (Example 12) 9.5 g of caustic soda and 1309 g of water, and further sodium aluminate (Al ２ O ３ : 23%, Na ２ O: 19.2%, H ２ Except for adding 16.2 g of O: 57.8%, the MFI-type zeolite aggregate of Example 12 according to the present invention was produced by the same method as in Example 1.

[0053] (Example 13) Use 5.3 g of caustic soda and 1307 g of water, and further add sodium aluminate (Al ２ O３ : 23%, Na ２ O: 19.2%, H ２ Except for adding 24.4 g of O: 57.8%, the MFI-type zeolite aggregate of Example 13 according to the present invention was produced by the same method as in Example 1.

[0054] [Conventional MFI-type Zeolites] (Comparative Examples 1-4) As conventional technology, commercially available MFI-type zeolites with different silica / alumina ratios (SAR) were prepared as Comparative Example 1 (SAR = 8000) (Figure 2 SEM image), Comparative Example 2 (SAR = 500), Comparative Example 3 (SAR = 100), and Comparative Example 4 (SAR = 30).

[0055] [Test 1: Composition Analysis] Elemental analysis of the examples and comparative examples was performed using a wavelength-dispersive X-ray fluorescence spectrometer (Rigaku ZSX primus II), and the silica / alumina ratio (SiO2) of the product was determined. ２ / Al ２ O ３ The following parameters were calculated: The target was Rh, the analytical curve was Kα, and other parameters were measured under the following conditions. A sample calcined at 550°C for 2 hours was used as the reference.

[0056] [Test 2: Particle size by laser diffraction scattering method] The particle size of each example and comparative example was measured using the laser diffraction scattering method with a particle size distribution analyzer (Malvern Mastersizer 3000).

[0057] [Test 3: Primary Particle Size] The particle size of the primary particles in the examples and the comparative example was measured from SEM images obtained using a scanning electron microscope (JEOL JSM-6510LA). Thirty particles were randomly selected, and the average of their major axes was taken as the primary particle size A [μm].

[0058] [Test 4: Pore Volume and Peak Top] Pore volume and pore distribution were measured for the examples and comparative examples using an automated mercury porosimeter (Micromeritics Autopore IV 9500) by mercury intrusion method. The range from 0.02 to 22 μm was measured, and the range from 0.05 to 2.0 μm was used to determine the pore volume [cm³]. ３The pore size distribution was measured every 0.01 μm up to 2 μm, and every 0.05 μm between 2 and 8 μm. The vertical axis was set to the differential pore volume [cm²]. ３ The peak top B of the pore diameter was determined from the pore distribution of pores smaller than 8 μm, using [ / g].

[0059] [Test 5: Filtration Time After Reaction] 1500 g of the reaction slurry was filtered using a 185 mm quantitative filter paper (5C) manufactured by Toyo Roshi Co., Ltd., placed in a funnel, and a circulating aspirator (WJ-20) manufactured by Shibata Scientific Co., Ltd. The time from when the slurry was added to the funnel until no more liquid could be seen from the top of the funnel was defined as the filtration time after the reaction.

[0060] [Test 6: Washing time after reaction] After measuring the filtration time after the reaction, 1200 mL of 50-60°C warm water was added to a funnel while the mixture was still being filtered by suction with an aspirator. The time until the warm water was no longer visible from the top of the funnel was defined as the washing time after the reaction.

[0061] [Test 7: Bulk Density] The bulk density of the examples and comparative examples was measured in accordance with JIS K 6220-1 7.7:2001.

[0062] [Test 8: BET Specific Surface Area] In accordance with JIS 8830, the BET specific surface area was measured for the examples and comparative examples using a specific surface area and pore distribution analyzer (Micromeritics Tristar II 3020). As a pretreatment, the samples were vacuum-dried at 300°C for 2 hours.

[0063] [Test 9: Oil Absorption] The oil absorption of the examples and comparative examples was measured in accordance with JIS K 5101-13-1:2004.

[0064] [Test 10: Toluene adsorption amount] The amount of toluene adsorbed was measured using BELSORP-MAX manufactured by Nippon Bell Co., Ltd., under conditions of an adsorption temperature of 25°C.

[0065] [Test 11: o-xylene adsorption amount] The amount of o-xylene adsorbed was measured using BELSORP-MAX manufactured by Nippon Bell Co., Ltd. at an adsorption temperature of 25°C and a relative pressure P / P0 = 0.1.

[0066] [Test Results] With respect to the MFI-type zeolite aggregates of Examples 1 to 13 and the MFI-type zeolites of Comparative Examples 1 to 4, the results of the aforementioned tests are shown in Table 2 (upper part: physical properties of raw materials (before production), lower part: physical properties of products (after production)). In Table 2, XCl / SiO ２ or X ２ SO ４ / SiO ２ Regarding the molar ratio, Examples 1 to 10, 12 and 13 show the XCl / SiO ２ molar ratio, and Example 11 shows the X ２ SO ４ / SiO ２ molar ratio. Based on the results of Test 4, the relationship between the pore diameter [nm] (horizontal axis) and the differential pore volume [cm ３ / g] (vertical axis) is shown in Figure 3 for Examples 1 to 10, in Figure 4 for Examples 11 to 13, and in Figure 5 for Comparative Examples 1 to 4. In Figure 3, each peak top of Examples 1 to 10 is indicated by reference numerals 1 to 10 and arrows; in Figure 4, each peak top of Examples 11 to 13 is indicated by reference numerals 11 to 13 and arrows; in Figure 5, each peak top of Comparative Examples 1 to 4 is indicated by reference numerals 1 to 4 and arrows. Furthermore, the relationship between the relative pressure [P / P0] (horizontal axis) and the toluene adsorption amount [wt%] (vertical axis) is shown in Figure 6 for Example 1 and Comparative Examples 1 and 2.

[0067]

[0068] [Discussion] Regarding the ratio (aggregation index) (B / A) of the peak top (B) of pore diameter measured by mercury porosimetry to the primary particle diameter (A) measured by electron microscopy, Comparative Examples (prior art) 1 to 4 showed 0.34 to 0.67, while Examples (present invention) 1 to 13 showed a larger value of 1.16 to 2.50. Regarding filtration time, Comparative Example 1 required several hours, while Examples 1 to 9 and 11 to 13 had an extremely short filtration time of 80 to 600 seconds, and Example 10 had a relatively short filtration time of 1080 seconds. Regarding washing time, Comparative Example 1 required several hours, while Examples 1, 3 to 9 and 11 to 13 had an extremely short washing time of 160 to 840 seconds, and Examples 2 and 10 had relatively short washing times of 1590 seconds and 3600 seconds, respectively.

[0069] Regarding bulk density, Comparative Examples 1 to 4 had a bulk density of 0.3 to 0.7 g / cm ３In contrast, in Examples 1 to 13, the values ​​were 0.39 to 0.50 g / cm³. ３ The specific surface area was 362 to 420 m² in Comparative Examples 1 to 4. ２ In terms of per g, Examples 1 to 13 also showed 398 to 460 m, which is equivalent to or higher than the comparative example. ２ The result was 1 / g. Regarding oil absorption, Comparative Examples 1-4 showed 33-49 mL / 100g. In contrast, Examples 1-6 and 11, in which sodium aluminate was not added, and Examples 12 and 13, in which an excess (16 g or more) was added, showed a similar or higher value of 42-55 mL / 100g, while Examples 7-10, in which an appropriate amount (6.6-12.5 g) of sodium aluminate was added, showed an even higher value of 63-77 mL / 100g. Furthermore, as shown in Figure 6, even in Example 1, which was aggregated, the toluene adsorption amount was almost the same as that obtained in Comparative Examples 1 and 2, which were primary particles.

[0070] Regarding the amount of o-xylene adsorbed, Comparative Examples 1 to 3 showed 0.7 to 5.0% by weight, while Examples 1, 7, 8, 12, and 13 showed 2.0 to 7.1% by weight, which was equivalent to or greater than the comparative examples. Specifically, when comparing the amount of o-xylene adsorbed at approximately equivalent particle sizes (laser method), Comparative Examples 3 and 2 (particle sizes 3.1 μm and 6.3 μm) showed 0.7 to 1.0% by weight, while Examples 1, 7, 8, 12, and 13 (particle sizes 3.1 to 4.3 μm) showed a larger 2.0 to 7.1% by weight. On the other hand, when comparing the particle size at approximately equivalent o-xylene adsorbed amounts, Comparative Example 1 (5.0% by weight) showed 0.8 μm, while Examples 1, 7, 8, 12, and 13 (2.0 to 7.1% by weight) showed 3.1 to 4.3 μm, resulting in better handling.

[0071] [Conclusion] Compared with conventional MFI-type zeolites (Comparative Examples 1 to 4), it was confirmed that the MFI-type zeolite aggregates of the present invention (Examples 1 to 13) have shorter filtration time and washing time, exhibit a high oil absorption amount, and have a specific surface area, toluene adsorption amount, and o-xylene adsorption amount that are substantially equal to or higher than those of the comparative examples. Therefore, it was confirmed that the MFI-type zeolite aggregate of the present invention can provide good filtration performance and washing performance, which are characteristics of large-diameter particles, and can provide high adsorption characteristics, which are characteristics of small-diameter particles, and the present invention has both characteristics of small-diameter particles and large-diameter particles. Furthermore, it was also confirmed that the aggregate has the characteristics of an aggregate due to the high oil absorption amount.

[0072] Regarding the numerical ranges of the physical properties of raw materials and products, it is considered that the same action and effect as described above (having both characteristics of small-diameter particles and large-diameter particles) can be obtained in the present invention not only in the ranges shown in Table 2 but also in numerical ranges in the vicinity thereof. That is, in Examples 1 to 13 of the present invention, XCl / SiO ２ or X ２ SO ４ / SiO ２ has a molar ratio of 0.1 to 0.25, Na ２ O / SiO ２ has a molar ratio of 0.036 to 0.06, the seed crystal based on SiO ２ is 0.5 to 5% by weight, and the aggregation index (B / A) is 1.16 to 0.25. However, not only these numerical ranges, XCl / SiO ２ or X ２ SO ４ / SiO ２ has a molar ratio of 0.05 or more, Na ２ O / SiO ２ has a molar ratio of 0.03 to 0.10, the seed crystal based on SiO ２ is 0.05 to 5% by weight, and even when the aggregation index (B / A) is 0.9 or more and 1 or more, it is considered that the same action and effect as described above can be obtained.

[0073] Further, in Examples 1 to 13 of the present invention, SiO ２ / Al ２ O ３ the molar ratio (product) was 50 or more, and the o-xylene adsorption amount was 2.0 to 7.1% by weight when the particle size (laser method) was 3.1 to 4.3 μm. However, not only these numerical ranges, SiO ２ / Al ２ O ３ We believe that the same effects can be obtained even when the molar ratio (product) is greater than 40, and even when the o-xylene adsorption amount at a laser-processed particle size of 2 to 8 μm is 2.0 to 10% by weight.

[0074] The MFI-type zeolite aggregates of the present invention can be used in a variety of industrial fields. For example, they can be used in applications such as adsorption, deodorization, drying, heavy metal treatment, waste oil treatment, decontamination, radioactive material absorbent, water treatment, filter media, catalysts / catalyst carriers, powder detergents, builders (detergent additives), ion exchange, soil improvement, adsorption and retention of fertilizer components, addition to livestock feed, addition to resins, adhesion, paints, underfloor humidity control, wall materials, cosmetics, and food additives.

Claims

1. An aggregate of primary particles, which are MFI-type zeolite particles, wherein the molar ratio of silica to alumina (SiO ２ / Al ２ O ３ An MFI-type zeolite aggregate characterized in that the ratio of the peak top of the pore diameter (B) measured by mercury intrusion to the primary particle diameter (A) measured by electron microscopy is greater than 40, and the ratio (B / A) of the peak top of the pore diameter measured by mercury intrusion method to the primary particle diameter (A) measured by electron microscopy is 0.9 or greater.

2. The MFI-type zeolite aggregate according to claim 1, wherein the ratio (B / A) of the peak top of the pore diameter (B) measured by mercury intrusion to the primary particle diameter (A) measured by electron microscopy is 1.0 to 5.

0.

3. Molar ratio of silica to alumina (SiO ２ / Al ２ O ３ The MFI-type zeolite aggregate according to claim 1, wherein the ratio of ) is 50 or more.

4. The MFI-type zeolite aggregate according to claim 1, wherein the amount of o-xylene adsorbed is 2.0 to 10% by weight.

5. A step of aging a raw material mixture containing a solid silica source, a template, an alkali metal salt, and an alkali solution to obtain an aged mixture; a step of adding seed crystals to the aged mixture; a step of subjecting the aged mixture to crystallization reaction under normal pressure while adding the seed crystals or after adding the seed crystals to produce aggregated MFI-type zeolite particles; and a step of calcining the aggregated MFI-type zeolite particles to remove the template and obtain an MFI-type zeolite aggregate, wherein the obtained MFI-type zeolite aggregate has a molar ratio of silica to alumina (SiO ２ / Al ２ O ３ ) of greater than 40, and the ratio (B / A) of the peak top (B) of pore diameter measured by mercury porosimetry to the primary particle diameter (A) measured by electron microscopy is 0.9 or more. A method for producing an MFI-type zeolite aggregate.

6. The manufacturing method according to claim 5, wherein the step of producing aggregated MFI-type zeolite particles is carried out by performing a crystallization reaction at a temperature of 60 to 99°C.

7. The manufacturing method according to claim 5, wherein the alkali metal of the alkali metal salt is one or more selected from sodium, potassium, or lithium, and the salt of the alkali metal salt is one or more selected from chloride salts, nitrates, sulfates, or carbonates.

8. In the raw material mixture, the molar ratio of alkali metal (X) chloride or sulfate to silica (XCl / SiO) ２ or X ２ SO ４ / SiO ２ The manufacturing method according to claim 7, wherein the ratio is 0.05 or more.

9. In the raw material mixture, the molar ratio of sodium oxide derived from the alkaline solution to silica (Na ２ O / SiO ２ The manufacturing method according to claim 5, wherein the ratio is 0.03 to 0.

10.

10. The manufacturing method according to claim 5, wherein the raw material mixture further comprises an alumina source.

11. The amount of seed crystal added is SiO in the raw material mixture. ２ The manufacturing method according to claim 5, wherein the amount is 0.05 to 5% by weight.

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