Method for producing MFI-type zeolite

Abstract

Provided is a method for producing an MFI-type zeolite using, as a raw material, a post-artificial-crystal-growth solution that has been used in growth of an artificial crystal carried out using a hydrothermal synthesis method. According to the present invention, an MFI-type zeolite is produced by a production method including: an addition step for adding an aluminum source, a seed crystal of an MFI-type zeolite, and sulfuric acid to a post-artificial-crystal-growth solution that has been used in growth of an artificial crystal carried out using a hydrothermal synthesis method, and obtaining a reaction mother liquid; and a heating step for heating the reaction mother liquid to generate the MFI-type zeolite.

Description

Method for producing MFI zeolite

[0001] The present disclosure relates to a method for producing MFI zeolite using a post-growth solution of artificial quartz crystal that has been used to grow artificial quartz crystal by hydrothermal synthesis.

[0002] Zeolites are crystalline aluminosilicates, and more than 200 different topologies have been reported. Each topology is labeled by the International Zeolite Association (IZA) with a combination of three letters, and representative zeolites include MFI, LTA, and FAU types. Among these, MFI zeolites are particularly suitable for use as catalysts in petroleum refining.

[0003] Generally, zeolites are produced by mixing (1) a silicon source such as colloidal silica or sodium silicate, (2) an aluminum source such as sodium aluminate or metallic aluminum, (3) a mineralizer such as sodium hydroxide, and (4) a structure-directing material such as a seed crystal or a quaternary ammonium salt to form a gel, and then aging the gel at a predetermined temperature for a predetermined time.

[0004] There is a known method for growing artificial quartz crystal using hydrothermal synthesis. In this method, a convection control plate is placed between two plates inside an artificial quartz crystal growth furnace (autoclave), with the growth material (raw quartz crystal) on the bottom and the seed quartz crystal on the top. The growth furnace is then filled with a growth solution (alkaline solution), sealed, and heated. The furnace is then set to a higher temperature below than above, allowing the growth solution to naturally convect within the furnace. This causes the growth material, which is melted at the bottom, to reach the top of the furnace, where it cools and becomes supersaturated, causing it to precipitate and grow on the seed quartz crystal. By repeating this process for a predetermined period of time, an artificial quartz crystal of a predetermined size can be obtained.

[0005] Regarding a method for producing artificial quartz crystal by hydrothermal synthesis, for example, Patent Document 1 discloses the use of a mixed solution of aqueous sodium hydroxide and aqueous sodium carbonate as the solution for growing the artificial quartz crystal, in which the sodium hydroxide concentration is set higher than the sodium carbonate concentration.

[0006] Japanese Patent Application Laid-Open No. 2001-322895

[0007] In quartz crystal growth using hydrothermal synthesis, the growth material (raw quartz crystal) is dissolved by convection of the artificial quartz crystal growth solution in the growth furnace. In other words, the post-crystal quartz crystal growth solution (hereinafter simply referred to as "post-quartz crystal growth solution") used to grow artificial quartz crystal using hydrothermal synthesis contains a silicon source derived from the quartz crystal. Therefore, the post-quartz crystal growth solution contains silicon and sodium. In the past, post-quartz crystal growth solution was often discarded as waste liquid, which caused problems such as environmental impact and the time and expense required for disposal.

[0008] Furthermore, as mentioned above, a silicon source is required for the production of zeolite, and colloidal silica, sodium silicate, etc. are generally used. Therefore, the present inventors investigated the use of quartz crystal growth solution as the silicon source. However, even when attempts were made to simply replace the silicon sources, such as colloidal silica and sodium silicate, used in conventional methods for producing MFI zeolite with quartz crystal growth solution, the resulting product was ANA zeolite, and there was a problem in that the desired MFI zeolite could not be obtained.

[0009] The present disclosure has been made in light of the above circumstances, and its purpose is to provide a method for producing MFI zeolite using, as a raw material, a post-growth solution of artificial quartz crystal that has been used to grow artificial quartz crystal by hydrothermal synthesis.

[0010] The method for producing MFI zeolite of the present disclosure, which has been made to solve the above-mentioned problems, is characterized by comprising: an addition step of adding an aluminum source, MFI zeolite seed crystals, and sulfuric acid to a post-artificial quartz crystal growth solution that has been used to grow artificial quartz crystal by hydrothermal synthesis to obtain a reaction mother liquor; and a heating step of heating the reaction mother liquor to produce MFI zeolite.

[0011] According to the above-described manufacturing method, MFI zeolite can be manufactured using a post-quartz crystal growth solution as a raw material, which in turn makes it possible to develop and manufacture functional materials while reducing raw material costs. Furthermore, since it is not necessary to prepare the silicon source and the aluminum source as separate solutions in advance, the manufacturing process can be simplified.

[0012] In the above manufacturing method, the used post-artificial quartz-crystal growth solution contains a sodium component, and when the mass of the sodium component in the post-artificial quartz-crystal growth solution is A in terms of sodium hydroxide, the mass of the sulfuric acid added in the adding step is B, and the mass ratio A / B is NSR, it is preferable that NSR is 1.5 or more and 7.5 or less.

[0013] In the above manufacturing method, it is preferable that in the adding step, sulfuric acid is added to the post-growth solution of the artificial quartz crystal before the seed crystal is added.

[0014] In the above manufacturing method, the addition step preferably includes an aging step, in which a pre-aging solution, in which at least an aluminum source has been added to the post-artificial quartz crystal growth solution, is maintained at a predetermined aging temperature to obtain a post-aging solution.

[0015] In the above manufacturing method, the pre-ripening solution is preferably prepared by adding an aluminum source and sulfuric acid to the post-ripening solution.

[0016] According to the manufacturing method of the present disclosure, MFI zeolite can be manufactured using as a raw material a post-growth solution of artificial quartz crystal that has been used to grow artificial quartz crystal by hydrothermal synthesis.

[0017] FIG. 1 is a cross-sectional view schematically illustrating an example of a reaction vessel (hydrothermal furnace) used in producing an MFI zeolite according to this embodiment. FIG. 2 is an X-ray diffraction (XRD) profile of the zeolites produced in Examples 1-1 to 1-4. FIG. 3 is an XRD profile of the zeolites produced in Examples 2-1 to 2-3. FIG. 4 is an XRD profile of the zeolites produced in Examples 2-4 to 2-7. FIG. 5 is a graph comparing the XRD profiles of the zeolites produced in Example 2-1 and Example 1-2. FIG. 6 is an example of an XRD profile obtained by XRD analysis, prepared to explain a method for calculating the crystallinity of a zeolite.

[0018] Hereinafter, the method for producing the MFI zeolite of the present disclosure will be described.

[0019] First Embodiment The method for producing MFI zeolite according to this embodiment includes: (1) an addition step of adding an aluminum source, MFI zeolite seed crystals, and sulfuric acid to a post-crystal growth solution that has been used to grow artificial quartz crystal by hydrothermal synthesis to obtain a reaction mother liquor; and (2) a heating step of heating the reaction mother liquor to produce MFI zeolite. First, the post-crystal growth solution as a raw material will be described, and then the addition step and the heating step will be described.

[0020] 1. Post-Crystal Growth Solution The method for producing MFI zeolite according to this embodiment uses, as a silicon source, a post-crystal growth solution (post-crystal growth solution) that has been used to grow artificial quartz by hydrothermal synthesis.

[0021] Here, when growing artificial quartz crystal using hydrothermal synthesis, the growth raw material (raw quartz crystal) and seed quartz crystal are placed in an artificial quartz crystal growth furnace (autoclave). The growth furnace is then filled with a growth solution, which is then sealed and heated. The growth solution is circulated within the growth furnace, causing the dissolved growth raw material to precipitate on the seed quartz crystal. This process is carried out for a predetermined period of time, causing the seed quartz crystal to precipitate and grow, producing an artificial quartz crystal of a predetermined size. An alkaline solution is used as the growth solution, which is generally an aqueous solution containing at least an alkaline-derived sodium component. Note that examples of alkaline-derived sodium components that can be used include sodium hydroxide and sodium carbonate. The post-quartz crystal growth solution in this embodiment contains at least sodium hydroxide as an alkaline component.

[0022] After growing an artificial quartz crystal using hydrothermal synthesis, a solution containing dissolved silicon dioxide remains in the growth furnace. This remaining solution is the post-quartz crystal growth solution used as the silicon source in this embodiment. In other words, the post-quartz crystal growth solution in this embodiment is an aqueous solution containing at least sodium hydroxide and silicon dioxide.

[0023] The post-crystal growth solution may contain other optional components as long as the effects of the present disclosure are not impaired. Examples of other optional components include lithium nitrate, as described in Patent Document 1.

[0024] The composition of the solution after crystal growth can be exemplified by a sodium hydroxide content of 3% by mass to 8% by mass, and a silicon dioxide content of 2% by mass to 10% by mass. These contents are determined by subjecting the solution after crystal growth to X-ray fluorescence analysis, converting the mass of Na obtained as a result of the measurement into the mass of NaOH, and converting the mass of Si obtained as a result of the measurement into the mass of SiO. ２ The specific measurement method is as described in the Examples section below.

[0025] 2. Addition Step The method for producing MFI zeolite according to this embodiment includes an addition step of adding an aluminum source, MFI zeolite seed crystals, and sulfuric acid to the post-quartz crystal growth solution to obtain a reaction mother liquor. Note that in this first embodiment, an embodiment in which an aging step is not performed in the addition step will be described, and an embodiment in which an aging step is performed will be described later as a second embodiment.

[0026] Among the examples described below, the addition step in "First Production Example of MFI Zeolite" includes an aluminum source addition step of adding an aluminum source to the post-quartz-growth solution to obtain a first solution, a seed crystal addition step of adding MFI zeolite seed crystals to the first solution to obtain a second solution, and a sulfuric acid addition step of adding sulfuric acid to the second solution to obtain a reaction mother liquor. In other words, the aluminum source, seed crystals, and sulfuric acid are added to the post-quartz-growth solution in this order, but the order of addition can be changed as long as the effects of the present disclosure are not impaired. The addition order in "First Production Example of MFI Zeolite" is as described above, but it is more preferable to add sulfuric acid to the post-quartz-growth solution before adding the seed crystals. As described above, the post-quartz-growth solution is alkaline, so adding seed crystals before sulfuric acid could result in some of the seed crystals dissolving, whereas adding sulfuric acid first prevents the seed crystals from coming into contact with the alkali.

[0027] The aluminum source added in the addition step is not particularly limited as long as it is water-soluble, and examples thereof include sodium aluminate, aluminum nitride, aluminum sulfate, and aluminum chloride. These aluminum sources may be used alone or in combination of two or more. Among these, sodium aluminate is preferred.

[0028] The blending ratio of the aluminum source added in the addition step to the silicon source in the post-quartz crystal growth solution is preferably a molar ratio of silicon atoms to aluminum atoms (Si / Al [mol / mol]) of 20 or less, more preferably 5 to 15. By having this molar ratio within the above range, MFI zeolite with few impurities can be produced. The aluminum source added in the addition step may be added after being adjusted to a predetermined concentration with purified water such as ion-exchanged water or distilled water.

[0029] As the seed crystals of MFI zeolite added in the adding step, MFI zeolite synthesized using an organic structure-directing agent (OSDA) may be used, or commercially available MFI zeolite may be used.

[0030] In the method for producing MFI zeolite according to this embodiment, the concentration of MFI zeolite seed crystals (mass ratio of the amount added) relative to the total mass of the raw materials (the total mass of the post-quartz-crystal growth solution and the additives in the adding step) can be around 1 mass%, for example, 0.5 mass% or more and 5.0 mass% or less.

[0031] The amount of sulfuric acid added in the addition step is an amount that results in an NSR of 1.5 or more and 7.5 or less, which is the mass ratio A / B where A is the mass of the sodium component in the solution after quartz crystal growth in terms of sodium hydroxide and B is the mass of sulfuric acid added, and an amount that results in an NSR of 3.0 or more and 4.0 or less. When the NSR is 1.5 or more and 7.5 or less, it is possible to produce MFI zeolite with few impurities, and in particular, when the NSR is 3.0 or more and 4.0 or less, it is possible to efficiently produce MFI zeolite. Note that the sulfuric acid added in the addition step may be added after being adjusted to a predetermined concentration with purified water such as ion-exchanged water or distilled water.

[0032] The reason for adding sulfuric acid in the addition step is as follows. As described above, simply replacing the silicon source in conventional zeolite production methods with the post-quartz crystal growth solution has not resulted in the production of MFI zeolite. This is thought to be due to the fact that the post-quartz crystal growth solution contains an excess amount of sodium (alkali component) relative to the amount of silicon contained therein. The inventors believed that if the reaction mother liquor for producing zeolite contains an excessive amount of sodium (alkali component), the seed crystals in the reaction mother liquor will dissolve during the reaction, inhibiting the formation of an MFI zeolite structure. The inventors discovered that MFI zeolite can be produced by adding sulfuric acid (preferably in an amount such that the NSR falls within a predetermined range) to the post-quartz crystal growth solution to weaken the alkalinity of the solution, and then synthesizing it by the seed crystal method. The inventors confirmed that MFI zeolite was not successfully produced even when hydrochloric acid, instead of sulfuric acid, was added to the post-quartz crystal growth solution to weaken the alkalinity of the solution.

[0033] 3. Heating Step The method for producing MFI zeolite according to this embodiment includes a heating step of heating the reaction mother liquor obtained in the adding step. By heating, the components in the reaction mother liquor react with each other to produce MFI zeolite.

[0034] In the heating step, the reaction mother liquor obtained in the adding step is heated in a sealed reaction vessel. The reaction vessel and the heating device used in the heating step are not particularly limited, but for example, a hydrothermal furnace and a dryer as shown in FIG.

[0035] Fig. 1 is a cross-sectional view schematically illustrating an example of a hydrothermal furnace as a reaction vessel used in producing MFI zeolite according to this embodiment. The hydrothermal furnace 10 shown in Fig. 1 is composed of an airtight container 11, which is an outer cylinder, and a heat-resistant container 14, which is an inner cylinder. The reaction mother liquor 1 is charged into the heat-resistant container 14, and the lid 15 of the heat-resistant container 14, the inner lid 13 of the airtight container 11, and the threaded lid 12 are closed. The screws 12a of the threaded lid 12 are tightened to seal the reaction mother liquor 1 in the heat-resistant container 14. The hydrothermal furnace 10 is then placed in a dryer 20, whereby the reaction mother liquor 1 can be heated in a sealed state.

[0036] The heating temperature of the reaction mother liquid in the heating step can be around 150° C., for example, from 120° C. to 200° C. The heating time can be around 24 hours, for example, from 15 hours to 72 hours.

[0037] After the heating step, the post-reaction solution in the reaction vessel is filtered and the residue is dried, whereby MFI zeolite can be obtained as a white powder.

[0038] Second Embodiment In the method for producing MFI zeolite according to the present disclosure, it is preferable to carry out an aging step. This aging step is carried out before the heating step described in the first embodiment, that is, within the addition step. Note that, except for the points described below, the second embodiment can have the same configuration as the first embodiment.

[0039] That is, the addition step in the second embodiment includes an aging step, in which a pre-aging solution, to which at least an aluminum source has been added, is maintained at a predetermined aging temperature to obtain a post-aging solution. By carrying out the aging step in this manner, it is possible to produce MFI zeolite exhibiting a higher degree of crystallinity. In this aging step, the pre-aging solution may be maintained at a predetermined aging temperature while standing (i.e., without stirring) to obtain a post-aging solution, but it is preferable to maintain the pre-aging solution at a predetermined aging temperature while stirring to obtain a post-aging solution.

[0040] The aging temperature in the aging step can be appropriately selected, for example, from room temperature to 100° C., and is preferably set to a temperature of 65° C. or higher and 85° C. or lower. The aging time can be about 24 hours, for example, from 15 hours to 72 hours.

[0041] The pre-aging solution is more preferably one obtained by adding an aluminum source and sulfuric acid to the post-artificial-quartz-crystal growth solution. In other words, the adding step according to the second embodiment preferably includes the steps of: obtaining a pre-aging solution by adding an aluminum source and sulfuric acid to the post-artificial-quartz-crystal growth solution; maturing the pre-aging solution to obtain a post-aging solution; and adding MFI zeolite seed crystals to the post-aging solution to obtain a reaction mother liquor.

[0042] Although the addition of sulfuric acid increases the viscosity of the solution to which it is added, adding sulfuric acid to the post-quartz-crystal-growth solution before aging while stirring it increases the uniformity of the post-aging solution obtained through the aging step, and prevents the seed crystals added to the post-aging solution from coming into contact with a strong alkali, making it possible to produce MFI zeolite that exhibits a higher degree of crystallinity. In other words, adding sulfuric acid to the post-quartz-crystal-growth solution before aging while stirring it makes it possible to uniformly adjust the alkalinity of the pre-aging solution to an appropriate strength within the solution, and makes it possible to produce MFI zeolite that exhibits a higher degree of crystallinity without dissolving the seed crystals.

[0043] The blending ratio of the aluminum source added in the addition step in the second embodiment to the silicon source in the post-quartz-crystal growth solution is preferably such that the molar ratio of silicon atoms to aluminum atoms (Si / Al [mol / mol]) is from 15 to 30, more preferably from 17 to 25, and even more preferably from 17 to 23. When the molar ratio is within the above range, an MFI zeolite with fewer impurities and a high degree of crystallinity can be produced.

[0044] The amount of sulfuric acid added in the addition step in the second embodiment can be an amount that results in an NSR of 1.2 or more and 3.0 or less, which is the mass ratio A / B, where A is the mass of the sodium component in the solution after quartz crystal growth in terms of sodium hydroxide, and B is the mass of sulfuric acid added. An amount that results in an NSR of 1.3 or more and 2.2 or less is preferred, and an amount that results in an NSR of 1.5 or more and 2.0 or less is more preferred. When the NSR is 1.2 or more and 3.0 or less, MFI zeolite can be produced, and in particular, when the NSR is 1.5 or more and 2.0 or less, MFI zeolite with fewer impurities and a high degree of crystallinity can be produced. Note that the sulfuric acid added in the addition step may be added after being adjusted to a predetermined concentration with purified water such as ion-exchanged water or distilled water.

[0045] The heating temperature of the reaction mother liquid in the heating step of the second embodiment can be, for example, from 120° C. to 170° C., and preferably from 130° C. to 160° C. The heating time can be, for example, from 10 hours to 80 hours, and preferably from 20 hours to 70 hours, and more preferably from 40 hours to 60 hours. When the heating temperature and heating time are within the above ranges, it is possible to produce an MFI zeolite that exhibits a higher degree of crystallinity.

[0046] Hereinafter, the method for producing MFI zeolite according to the present disclosure will be specifically described based on examples.

[0047] 1. First Production Example of MFI Zeolite The first production example is an example in which MFI zeolite was produced in accordance with the first embodiment (an embodiment in which the aging step is not carried out).

[0048] Example 1-1 (NSR = 7.32) - Collection and filtration process of post-quartz crystal growth solution - 23.85 g of post-quartz crystal growth solution was collected from an artificial quartz crystal growth furnace (autoclave). The collected post-quartz crystal growth solution was filtered to remove foreign matter.

[0049] - Aluminum Source Addition Step - 1.14 g of a 20 mass % aqueous sodium aluminate solution prepared by dissolving 0.228 g of sodium aluminate (manufactured by Kanto Chemical Co., Inc., standard: Deer Grade 1) in 0.912 g of ion-exchanged water was added to the filtered post-crystal growth solution, and the mixture was stirred and mixed for 10 minutes to obtain a first solution.

[0050] -Seed Crystal Addition Step- 0.27 g of MFI zeolite seed crystals (manufactured by Tosoh Corporation, model number: HSZ-840NHA) were added to the obtained first solution, and the mixture was stirred for 10 minutes to dissolve, thereby obtaining a second solution.

[0051] -Sulfuric acid addition step- To the obtained second solution, 1.63 g of an aqueous solution having a sulfuric acid concentration of 9.6 mass %, obtained by dissolving 0.163 g of sulfuric acid with a purity of 96% (manufactured by Kanto Chemical Co., Inc., standard: special grade) in 1.467 g of ion-exchanged water, was added, and the mixture was stirred and mixed for 10 minutes, thereby obtaining a reaction mother liquid.

[0052] -Heating Step- The obtained reaction mother liquor was poured into a hydrothermal furnace. Taking into account the increase in internal pressure of the hydrothermal furnace during heating, it is preferable to adjust the amount of reaction mother liquor poured so that the filling rate of the hydrothermal furnace is 75% or less. In this embodiment, the amount of reaction mother liquor poured was an amount that would result in a filling rate of approximately 50% of the hydrothermal furnace. Note that this filling rate is a guideline; in this experiment, the filling rate of approximately 50% was achieved by pouring the entire amount of the obtained reaction mother liquor. After pouring the reaction mother liquor, the hydrothermal furnace was covered with a lid to seal the interior. Next, the hydrothermal furnace was placed in a dryer set at 150°C and heated for 24 hours. The hydrothermal furnace used had the structure shown in Figure 1, with the airtight container 11 (outer cylinder), threaded lid 12, and inner lid 13 being made of stainless steel (SUS), and the heat-resistant container 14 (inner cylinder) and its lid 15 being made of polyethylene terephthalate.

[0053] - Collection of Zeolite Powder - After heating for 24 hours, the hydrothermal furnace was removed, the solution inside the hydrothermal furnace was filtered, and the zeolite powder was collected.

[0054] Example 1-2 (NSR = 3.66) - Collection and filtration process of post-quartz crystal growth solution - 23.85 g of post-quartz crystal growth solution was collected from an artificial quartz crystal growth furnace (autoclave). The collected post-quartz crystal growth solution was filtered to remove foreign matter.

[0055] - Aluminum Source Addition Step - 1.14 g of a 20 mass % aqueous sodium aluminate solution prepared by dissolving 0.228 g of sodium aluminate (manufactured by Kanto Chemical Co., Inc., standard: Deer Grade 1) in 0.912 g of ion-exchanged water was added to the filtered post-crystal growth solution, and the mixture was stirred and mixed for 10 minutes to obtain a first solution.

[0056] -Seed Crystal Addition Step- 0.28 g of MFI zeolite seed crystals (manufactured by Tosoh Corporation, model number: HSZ-840NHA) were added to the obtained first solution, and the mixture was stirred for 10 minutes to dissolve, thereby obtaining a second solution.

[0057] - Sulfuric acid addition step - To the obtained second solution, 3.26 g of an aqueous solution of sulfuric acid having a concentration of 9.6 mass %, obtained by dissolving 0.326 g of sulfuric acid with a purity of 96% (manufactured by Kanto Chemical Co., Inc., standard: special grade) in 2.934 g of ion-exchanged water, was added, and the mixture was stirred and mixed for 10 minutes to obtain a reaction mother liquid.

[0058] - Heating step - The obtained reaction mother liquor was charged into a hydrothermal furnace. The amount of reaction mother liquor charged was an amount that would result in a filling rate of approximately 50% relative to the hydrothermal furnace. Note that this filling rate is a guideline, and in this experiment, the filling rate reached approximately 50% by charging the entire amount of the reaction mother liquor obtained. After charging the reaction mother liquor, the hydrothermal furnace was covered with a lid to seal the inside. Next, the hydrothermal furnace was charged into a dryer set at 150°C and heated for 24 hours. The hydrothermal furnace used was the same as in Example 1-1.

[0059] - Collection of Zeolite Powder - After heating for 24 hours, the hydrothermal furnace was removed, the solution inside the hydrothermal furnace was filtered, and the zeolite powder was collected.

[0060] Example 1-3 (NSR = 2.44) - Collection and filtration process of post-quartz crystal growth solution - 23.85 g of post-quartz crystal growth solution was collected from an artificial quartz crystal growth furnace (autoclave). The collected post-quartz crystal growth solution was filtered to remove foreign matter.

[0061] - Aluminum Source Addition Step (Aluminum Source Addition Step) - 1.14 g of a 20 mass % aqueous sodium aluminate solution prepared by dissolving 0.228 g of sodium aluminate (manufactured by Kanto Chemical Co., Inc., standard: Deer Grade 1) in 0.912 g of ion-exchanged water was added to the filtered post-crystal growth solution, and the mixture was stirred and mixed for 10 minutes to obtain a first solution.

[0062] -Seed Crystal Addition Step- 0.30 g of MFI zeolite seed crystals (manufactured by Tosoh Corporation, model number: HSZ-840NHA) were added to the obtained first solution, and the mixture was stirred for 10 minutes to dissolve, thereby obtaining a second solution.

[0063] -Sulfuric acid addition step- To the obtained second solution, 4.89 g of an aqueous solution having a sulfuric acid concentration of 9.6 mass %, obtained by dissolving 0.489 g of sulfuric acid with a purity of 96% (manufactured by Kanto Chemical Co., Inc., standard: special grade) in 4.401 g of ion-exchanged water, was added, and the mixture was stirred and mixed for 10 minutes, thereby obtaining a reaction mother liquid.

[0064] - Heating step - The obtained reaction mother liquor was charged into a hydrothermal furnace. The amount of reaction mother liquor charged was an amount that would result in a filling rate of approximately 50% relative to the hydrothermal furnace. Note that this filling rate is a guideline, and in this experiment, the filling rate reached approximately 50% by charging the entire amount of the reaction mother liquor obtained. After charging the reaction mother liquor, the hydrothermal furnace was covered with a lid to seal the inside. Next, the hydrothermal furnace was charged into a dryer set at 150°C and heated for 24 hours. The hydrothermal furnace used was the same as in Example 1-1.

[0065] - Collection of Zeolite Powder - After heating for 24 hours, the hydrothermal furnace was removed, the solution inside the hydrothermal furnace was filtered, and the zeolite powder was collected.

[0066] Example 1-4 (NSR = 1.83) - Collection and filtration process of post-quartz crystal growth solution - 23.85 g of post-quartz crystal growth solution was collected from an artificial quartz crystal growth furnace (autoclave). The collected post-quartz crystal growth solution was filtered to remove foreign matter.

[0067] - Aluminum Source Addition Step - 1.14 g of a 20 mass % aqueous sodium aluminate solution prepared by dissolving 0.228 g of sodium aluminate (manufactured by Kanto Chemical Co., Inc., standard: Deer Grade 1) in 0.912 g of ion-exchanged water was added to the filtered post-crystal growth solution, and the mixture was stirred and mixed for 10 minutes to obtain a first solution.

[0068] -Seed Crystal Addition Step- 0.32 g of MFI zeolite seed crystals (manufactured by Tosoh Corporation, model number: HSZ-840NHA) were added to the obtained first solution, and the mixture was stirred for 10 minutes to dissolve, thereby obtaining a second solution.

[0069] - Sulfuric acid addition step - To the obtained second solution, 6.52 g of an aqueous solution of sulfuric acid having a concentration of 9.6 mass %, obtained by dissolving 0.652 g of sulfuric acid with a purity of 96% (manufactured by Kanto Chemical Co., Inc., standard: special grade) in 5.868 g of ion-exchanged water, was added, and the mixture was stirred and mixed for 10 minutes, thereby obtaining a reaction mother liquid.

[0070] - Heating step - The obtained reaction mother liquor was charged into a hydrothermal furnace. The amount of reaction mother liquor charged was an amount that would result in a filling rate of approximately 50% relative to the hydrothermal furnace. Note that this filling rate is a guideline, and in this experiment, the filling rate reached approximately 50% by charging the entire amount of the reaction mother liquor obtained. After charging the reaction mother liquor, the hydrothermal furnace was covered with a lid to seal the inside. Next, the hydrothermal furnace was charged into a dryer set at 150°C and heated for 24 hours. The hydrothermal furnace used was the same as in Example 1-1.

[0071] - Collection of Zeolite Powder - After heating for 24 hours, the hydrothermal furnace was removed, the solution inside the hydrothermal furnace was filtered, and the zeolite powder was collected.

[0072] Table 1 below summarizes the amounts and ratios of raw materials used in Examples 1-1 to 1-4. NSR in Table 1 is the mass ratio A / B, where A is the mass of the alkalinity-derived sodium component in the post-quartz crystal growth solution, converted into sodium hydroxide, and B is the mass of sulfuric acid added in the sulfuric acid addition step. The mass A of the sodium component in the post-quartz crystal growth solution was calculated from the results of the "X-ray fluorescence analysis of the post-quartz crystal growth solution" described below.

[0073]

[0074] 2. Second Production Example of MFI Zeolite The second production example is an example in which MFI zeolite was produced in accordance with the second embodiment (embodiment in which an aging step is carried out).

[0075] Example 2-1 - Collection and filtration process of post-quartz crystal growth solution - 19.20 g of post-quartz crystal growth solution was collected from an artificial quartz crystal growth furnace (autoclave). The collected post-quartz crystal growth solution was filtered to remove foreign matter.

[0076] - Aluminum Source Addition Step - 0.46 g of a 20 mass % aqueous sodium aluminate solution prepared by dissolving 0.092 g of sodium aluminate (manufactured by Kanto Chemical Co., Inc., standard: Deer Grade 1) in 0.368 g of ion-exchanged water was added to the filtered solution after quartz crystal growth, and the mixture was stirred and mixed for 30 minutes (Si / Al = 20).

[0077] - Sulfuric acid addition step - 5.34 g of an aqueous solution with a sulfuric acid concentration of 9.6 mass %, prepared by dissolving 0.53 g of 96% purity sulfuric acid (manufactured by Kanto Chemical Co., Inc., standard: special grade) in 4.81 g of ion-exchanged water, was added to the quartz crystal growth solution after the addition of the aluminum source, and the mixture was stirred and mixed for 30 minutes to obtain a pre-aging solution (NSR = 1.5).

[0078] -Aging Step- The obtained pre-aging solution was heated with a hot stirrer and stirred while maintaining the temperature at 75° C. This was continued for 24 hours to age the pre-aging solution, thereby obtaining a post-aging solution.

[0079] -Seed Crystal Addition Step- 0.25 g of MFI zeolite seed crystals (manufactured by Tosoh Corporation, model number: HSZ-840NHA) were added to the obtained aged solution, and the mixture was stirred for 10 minutes to dissolve, thereby obtaining a reaction mother liquor.

[0080] - Heating step - The obtained reaction mother liquor was charged into a hydrothermal furnace. The amount of reaction mother liquor charged was an amount that would result in a filling rate of approximately 50% relative to the hydrothermal furnace. Note that this filling rate is a guideline, and in this experiment, the filling rate reached approximately 50% by charging the entire amount of the reaction mother liquor obtained. After charging the reaction mother liquor, the hydrothermal furnace was covered with a lid to seal the inside. Next, the hydrothermal furnace was charged into a dryer set at 140°C and heated for 48 hours. The hydrothermal furnace used was the same as in Example 1-1.

[0081] - Collection of Zeolite Powder - After heating for 48 hours, the hydrothermal furnace was removed, the solution inside the hydrothermal furnace was filtered, and the zeolite powder was collected.

[0082] [Example 2-2] - Collection and filtration process of post-quartz crystal growth solution - 20.29 g of post-quartz crystal growth solution was collected from an artificial quartz crystal growth furnace (autoclave). The collected post-quartz crystal growth solution was filtered to remove foreign matter.

[0083] - Aluminum Source Addition Step - 0.48 g of a 20 mass % aqueous sodium aluminate solution prepared by dissolving 0.096 g of sodium aluminate (manufactured by Kanto Chemical Co., Inc., standard: Deer Grade 1) in 0.384 g of ion-exchanged water was added to the filtered solution after quartz crystal growth, and the mixture was stirred and mixed for 30 minutes (Si / Al = 20).

[0084] - Sulfuric acid addition step - 4.23 g of an aqueous solution with a sulfuric acid concentration of 9.6 mass %, prepared by dissolving 0.423 g of 96% purity sulfuric acid (manufactured by Kanto Chemical Co., Inc., standard: special grade) in 3.807 g of ion-exchanged water, was added to the quartz crystal growth solution after the addition of the aluminum source, and the mixture was stirred and mixed for 30 minutes to obtain a pre-aging solution (NSR = 2.0).

[0085] -Aging Step- The obtained pre-aging solution was heated with a hot stirrer and stirred while maintaining the temperature at 75° C. This was continued for 24 hours to age the pre-aging solution, thereby obtaining a post-aging solution.

[0086] -Seed Crystal Addition Step- 0.25 g of MFI zeolite seed crystals (manufactured by Tosoh Corporation, model number: HSZ-840NHA) were added to the obtained aged solution, and the mixture was stirred for 10 minutes to dissolve, thereby obtaining a reaction mother liquor.

[0087] - Heating step - The obtained reaction mother liquor was charged into a hydrothermal furnace. The amount of reaction mother liquor charged was an amount that would result in a filling rate of approximately 50% relative to the hydrothermal furnace. Note that this filling rate is a guideline, and in this experiment, the filling rate reached approximately 50% by charging the entire amount of the reaction mother liquor obtained. After charging the reaction mother liquor, the hydrothermal furnace was covered with a lid to seal the inside. Next, the hydrothermal furnace was charged into a dryer set at 140°C and heated for 48 hours. The hydrothermal furnace used was the same as in Example 1-1.

[0088] - Collection of Zeolite Powder - After heating for 48 hours, the hydrothermal furnace was removed, the solution inside the hydrothermal furnace was filtered, and the zeolite powder was collected.

[0089] [Example 2-3] - Collection and filtration process of post-quartz crystal growth solution - 20.29 g of post-quartz crystal growth solution was collected from an artificial quartz crystal growth furnace (autoclave). The collected post-quartz crystal growth solution was filtered to remove foreign matter.

[0090] - Aluminum Source Addition Step - 0.48 g of a 20 mass % aqueous sodium aluminate solution prepared by dissolving 0.096 g of sodium aluminate (manufactured by Kanto Chemical Co., Inc., standard: Deer Grade 1) in 0.384 g of ion-exchanged water was added to the filtered solution after quartz crystal growth, and the mixture was stirred and mixed for 30 minutes (Si / Al = 20).

[0091] - Sulfuric acid addition step - 4.23 g of an aqueous solution with a sulfuric acid concentration of 9.6 mass %, prepared by dissolving 0.423 g of 96% purity sulfuric acid (manufactured by Kanto Chemical Co., Inc., standard: special grade) in 3.807 g of ion-exchanged water, was added to the quartz crystal growth solution after the addition of the aluminum source, and the mixture was stirred and mixed for 30 minutes to obtain a pre-aging solution (NSR = 2.0).

[0092] -Aging Step- The obtained pre-aging solution was heated with a hot stirrer and stirred while maintaining the temperature at 75° C. This was continued for 24 hours to age the pre-aging solution, thereby obtaining a post-aging solution.

[0093] -Seed Crystal Addition Step- 0.25 g of MFI zeolite seed crystals (manufactured by Tosoh Corporation, model number: HSZ-840NHA) were added to the obtained aged solution, and the mixture was stirred for 10 minutes to dissolve, thereby obtaining a reaction mother liquor.

[0094] - Heating step - The obtained reaction mother liquor was charged into a hydrothermal furnace. The amount of reaction mother liquor charged was an amount that would result in a filling rate of approximately 50% relative to the hydrothermal furnace. Note that this filling rate is a guideline, and in this experiment, the filling rate reached approximately 50% by charging the entire amount of the reaction mother liquor obtained. After charging the reaction mother liquor, the hydrothermal furnace was covered with a lid to seal the inside. Next, the hydrothermal furnace was charged into a dryer set at 150°C and heated for 48 hours. The hydrothermal furnace used was the same as in Example 1-1.

[0095] - Collection of Zeolite Powder - After heating for 48 hours, the hydrothermal furnace was removed, the solution inside the hydrothermal furnace was filtered, and the zeolite powder was collected.

[0096] [Example 2-4] - Collection and filtration process of post-quartz crystal growth solution - 23.98 g of post-quartz crystal growth solution was collected from an artificial quartz crystal growth furnace (autoclave). The collected post-quartz crystal growth solution was filtered to remove foreign matter.

[0097] - Aluminum Source Addition Step - 0.46 g of a 20 mass % aqueous sodium aluminate solution prepared by dissolving 0.092 g of sodium aluminate (manufactured by Kanto Chemical Co., Inc., standard: Deer Grade 1) in 0.368 g of ion-exchanged water was added to the filtered solution after quartz crystal growth, and the mixture was stirred and mixed for 30 minutes (Si / Al = 25).

[0098] - Sulfuric acid addition step - 5.00 g of an aqueous solution with a sulfuric acid concentration of 9.6 mass %, prepared by dissolving 0.500 g of 96% purity sulfuric acid (manufactured by Kanto Chemical Co., Inc., standard: special grade) in 4.500 g of ion-exchanged water, was added to the quartz crystal growth solution after the addition of the aluminum source, and the mixture was stirred and mixed for 30 minutes to obtain a pre-aging solution (NSR = 2.0).

[0099] -Aging Step- The obtained pre-aging solution was heated with a hot stirrer and stirred while maintaining the temperature at 75° C. This was continued for 24 hours to age the pre-aging solution, thereby obtaining a post-aging solution.

[0100] -Seed Crystal Addition Step- 0.25 g of MFI zeolite seed crystals (manufactured by Tosoh Corporation, model number: HSZ-840NHA) were added to the obtained aged solution, and the mixture was stirred for 10 minutes to dissolve, thereby obtaining a reaction mother liquor.

[0101] - Heating step - The obtained reaction mother liquor was charged into a hydrothermal furnace. The amount of reaction mother liquor charged was an amount that would result in a filling rate of approximately 50% relative to the hydrothermal furnace. Note that this filling rate is a guideline, and in this experiment, the filling rate reached approximately 50% by charging the entire amount of the reaction mother liquor obtained. After charging the reaction mother liquor, the hydrothermal furnace was covered with a lid to seal the inside. Next, the hydrothermal furnace was charged into a dryer set at 140°C and heated for 48 hours. The hydrothermal furnace used was the same as in Example 1-1.

[0102] - Collection of Zeolite Powder - After heating for 48 hours, the hydrothermal furnace was removed, the solution inside the hydrothermal furnace was filtered, and the zeolite powder was collected.

[0103] [Example 2-5] - Collection and filtration process of post-quartz crystal growth solution - 20.29 g of post-quartz crystal growth solution was collected from an artificial quartz crystal growth furnace (autoclave). The collected post-quartz crystal growth solution was filtered to remove foreign matter.

[0104] - Aluminum Source Addition Step - 0.48 g of a 20 mass % aqueous sodium aluminate solution prepared by dissolving 0.096 g of sodium aluminate (manufactured by Kanto Chemical Co., Inc., standard: Deer Grade 1) in 0.384 g of ion-exchanged water was added to the filtered solution after quartz crystal growth, and the mixture was stirred and mixed for 30 minutes (Si / Al = 20).

[0105] - Sulfuric acid addition step - 4.23 g of an aqueous solution with a sulfuric acid concentration of 9.6 mass %, prepared by dissolving 0.423 g of 96% purity sulfuric acid (manufactured by Kanto Chemical Co., Inc., standard: special grade) in 3.807 g of ion-exchanged water, was added to the quartz crystal growth solution after the addition of the aluminum source, and the mixture was stirred and mixed for 30 minutes to obtain a pre-aging solution (NSR = 2.0).

[0106] -Aging Step- The obtained pre-aging solution was heated with a hot stirrer and stirred while maintaining the temperature at 75° C. This was continued for 24 hours to age the pre-aging solution, thereby obtaining a post-aging solution.

[0107] -Seed Crystal Addition Step- 0.25 g of MFI zeolite seed crystals (manufactured by Tosoh Corporation, model number: HSZ-840NHA) were added to the obtained aged solution, and the mixture was stirred for 10 minutes to dissolve, thereby obtaining a reaction mother liquor.

[0108] - Heating step - The obtained reaction mother liquor was charged into a hydrothermal furnace. The amount of reaction mother liquor charged was an amount that would result in a filling rate of approximately 50% relative to the hydrothermal furnace. Note that this filling rate is a guideline, and in this experiment, the filling rate reached approximately 50% by charging the entire amount of the reaction mother liquor obtained. After charging the reaction mother liquor, the hydrothermal furnace was covered with a lid to seal the inside. Next, the hydrothermal furnace was charged into a dryer set at 140°C and heated for 24 hours. The hydrothermal furnace used was the same as in Example 1-1.

[0109] - Collection of Zeolite Powder - After heating for 24 hours, the hydrothermal furnace was removed, the solution inside the hydrothermal furnace was filtered, and the zeolite powder was collected.

[0110] [Example 2-6] - Collection and filtration process of post-quartz crystal growth solution - 20.29 g of post-quartz crystal growth solution was collected from an artificial quartz crystal growth furnace (autoclave). The collected post-quartz crystal growth solution was filtered to remove foreign matter.

[0111] - Aluminum Source Addition Step - 0.48 g of a 20 mass % aqueous sodium aluminate solution prepared by dissolving 0.096 g of sodium aluminate (manufactured by Kanto Chemical Co., Inc., standard: Deer Grade 1) in 0.384 g of ion-exchanged water was added to the filtered solution after quartz crystal growth, and the mixture was stirred and mixed for 30 minutes (Si / Al = 20).

[0112] - Sulfuric acid addition step - 4.23 g of an aqueous solution with a sulfuric acid concentration of 9.6 mass %, prepared by dissolving 0.423 g of 96% purity sulfuric acid (manufactured by Kanto Chemical Co., Inc., standard: special grade) in 3.807 g of ion-exchanged water, was added to the quartz crystal growth solution after the addition of the aluminum source, and the mixture was stirred and mixed for 30 minutes to obtain a pre-aging solution (NSR = 2.0).

[0113] -Aging Step- The obtained pre-aging solution was heated with a hot stirrer and stirred while maintaining the temperature at 75° C. This was continued for 24 hours to age the pre-aging solution, thereby obtaining a post-aging solution.

[0114] -Seed Crystal Addition Step- 0.25 g of MFI zeolite seed crystals (manufactured by Tosoh Corporation, model number: HSZ-840NHA) were added to the obtained aged solution, and the mixture was stirred for 10 minutes to dissolve, thereby obtaining a reaction mother liquor.

[0115] - Heating step - The obtained reaction mother liquor was charged into a hydrothermal furnace. The amount of reaction mother liquor charged was an amount that would result in a filling rate of approximately 50% relative to the hydrothermal furnace. Note that this filling rate is a guideline, and in this experiment, the filling rate reached approximately 50% by charging the entire amount of the reaction mother liquor obtained. After charging the reaction mother liquor, the hydrothermal furnace was covered with a lid to seal the inside. Next, the hydrothermal furnace was charged into a dryer set at 150°C and heated for 12 hours. The hydrothermal furnace used was the same as in Example 1-1.

[0116] - Collection of Zeolite Powder - After heating for 12 hours, the hydrothermal furnace was removed, the solution inside the hydrothermal furnace was filtered, and the zeolite powder was collected.

[0117] [Example 2-7] - Collection and filtration process of post-quartz crystal growth solution - 20.29 g of post-quartz crystal growth solution was collected from an artificial quartz crystal growth furnace (autoclave). The collected post-quartz crystal growth solution was filtered to remove foreign matter.

[0118] - Aluminum Source Addition Step - 0.48 g of a 20 mass % aqueous sodium aluminate solution prepared by dissolving 0.096 g of sodium aluminate (manufactured by Kanto Chemical Co., Inc., standard: Deer Grade 1) in 0.384 g of ion-exchanged water was added to the filtered solution after quartz crystal growth, and the mixture was stirred and mixed for 30 minutes (Si / Al = 20).

[0119] - Sulfuric acid addition step - 4.23 g of an aqueous solution with a sulfuric acid concentration of 9.6 mass %, prepared by dissolving 0.423 g of 96% purity sulfuric acid (manufactured by Kanto Chemical Co., Inc., standard: special grade) in 3.807 g of ion-exchanged water, was added to the quartz crystal growth solution after the addition of the aluminum source, and the mixture was stirred and mixed for 30 minutes to obtain a pre-aging solution (NSR = 2.0).

[0120] -Aging Step- The obtained pre-aging solution was heated with a hot stirrer and stirred while maintaining the temperature at 75° C. This was continued for 24 hours to age the pre-aging solution, thereby obtaining a post-aging solution.

[0121] -Seed Crystal Addition Step- 0.25 g of MFI zeolite seed crystals (manufactured by Tosoh Corporation, model number: HSZ-840NHA) were added to the obtained aged solution, and the mixture was stirred for 10 minutes to dissolve, thereby obtaining a reaction mother liquor.

[0122] - Heating step - The obtained reaction mother liquor was charged into a hydrothermal furnace. The amount of reaction mother liquor charged was an amount that would result in a filling rate of approximately 50% relative to the hydrothermal furnace. Note that this filling rate is a guideline, and in this experiment, the filling rate reached approximately 50% by charging the entire amount of the reaction mother liquor obtained. After charging the reaction mother liquor, the hydrothermal furnace was covered with a lid to seal the inside. Next, the hydrothermal furnace was charged into a dryer set at 150°C and heated for 24 hours. The hydrothermal furnace used was the same as in Example 1-1.

[0123] - Collection of Zeolite Powder - After heating for 24 hours, the hydrothermal furnace was removed, the solution inside the hydrothermal furnace was filtered, and the zeolite powder was collected.

[0124] Table 2 below summarizes the heating step conditions (heating time and heating temperature), raw material input ratios, and crystallinity of the resulting zeolite in Examples 2-1 to 2-7. NSR in Table 2 is the mass ratio A / B, where A is the mass of the alkalinity-derived sodium component in the post-quartz crystal growth solution, converted to sodium hydroxide, and B is the mass of sulfuric acid added in the sulfuric acid addition step. The mass A of the sodium component in the post-quartz crystal growth solution was calculated from the results of "X-ray fluorescence analysis of the post-quartz crystal growth solution" described later. The crystallinity in Table 2 was calculated using the method described later from the results of "Analysis of the product using an X-ray diffraction analyzer" described later.

[0125]

[0126] 3. Measurement and Evaluation - Fluorescent X-ray analysis of the solution after crystal growth - NaOH and SiO in the solution after crystal growth used as raw material in each example ２ X-ray fluorescence analysis (XRF) was performed to measure the content (% by mass) of . Specifically, the solution after quartz crystal growth was sealed in a low-vacuum liquid sample capsule, and measurement was performed in a vacuum environment using an energy dispersive X-ray fluorescence analyzer (manufactured by JEOL Ltd., model: JSX-1000S).

[0127] Quantitative calculation was performed using the thin film FP method using the spectrum obtained in the measurement. As a result, the content in the solution after quartz crystal growth was calculated by converting the mass of Na obtained as a result of the measurement into the mass of NaOH, and the mass of Si obtained as a result of the measurement into the mass of SiO ２ In terms of mass, NaOH was 4.8 mass%, SiO ２ was 6.9% by mass.

[0128] - Analysis of Products Using an X-Ray Diffraction Analyzer - X-ray diffraction (XRD) analysis was performed to measure the crystal structure of the zeolite produced in each example. Specifically, an X-ray diffraction analyzer (manufactured by Rigaku Corporation, model: MiniFlex600) was used to perform the measurement under the following measurement conditions: Radiation source: Cu (measured using Kα rays) Tube voltage: 40.0 KV Tube current: 15.0 mA Data range: 5 deg to 50 deg Sampling interval: 0.01 deg Scan rate: 10.00 deg / min Divergence slit: 1.25 deg

[0129] Figure 6 shows an example of an XRD profile obtained by X-ray diffraction (XRD) analysis, where pattern (1) in Figure 6 is raw data, pattern (2) is background data, and pattern (3) is the raw data with the background removed. The acquisition and removal of this background data were performed using a function provided in the X-ray diffraction analysis device. Note that the XRD profiles in Figures 2 to 5 show patterns corresponding to (3) (i.e., data after background removal).

[0130] Next, the crystallinity of the zeolite was calculated by integrating the region of the XRD profile where 2θ (diffraction angle) was 20° to 30°. Specifically, in this region, the integrated value (area) of (3), which is the data after background removal, was defined as A, and the integrated value (area) of (1), which is the raw data, was defined as B, and the crystallinity of the zeolite was defined as A / B. That is, the formula for calculating the crystallinity of the zeolite in percentage is as follows: Crystallinity of Zeolite [%] = (A / B) × 100

[0131] - Evaluation of Zeolite Produced in First Production Example (without carrying out an Aging Step) - Figure 2 shows XRD profiles of the zeolites produced in Examples 1-1 to 1-4. Note that the model peaks in Figure 2 are peaks of MSI zeolite in the database of the IZA (International Zeolite Association), and can be confirmed by accessing their website (https: / / america.iza-structure.org / IZA-SC / pow_pat.php?ID=180).

[0132] According to FIG. 2, the peak patterns of the XRD profiles of the zeolites produced in Examples 1-1 to 1-4 coincide with the model peak patterns of MFI zeolite, and it can be seen that MFI zeolite was produced in Examples 1-1 to 1-4.

[0133] Furthermore, among Examples 1-1 to 1-4, Example 1-2 (an example of NSR = 3.66) in which the NSR was 3.0 or more and 4.0 or less exhibited the largest peak pattern of MFI zeolite, indicating that MFI zeolite was efficiently produced.

[0134] - Evaluation of Zeolites Produced in Second Production Example (Implementation of an Aging Step) - Figure 3 shows XRD profiles of the zeolites produced in Examples 2-1 to 2-3, and Figure 4 shows XRD profiles of the zeolites produced in Examples 2-4 to 2-7. The peak patterns in the XRD profiles of the zeolites produced in Examples 2-1 to 2-7 match the model peak patterns of MFI zeolite, which shows that MFI zeolite was produced in Examples 2-1 to 2-7.

[0135] In addition, according to the measurement results of the crystallinity of the zeolite shown in Table 2, it can be seen that, among Examples 2-1 to 2-7, Examples 2-1 to 2-3, in which the heating time in the heating step was 40 hours or more and 60 hours or less, the molar ratio of silicon atoms to aluminum atoms (Si / Al [mol / mol]) was 17 or more and 23 or less, and the NSR was 1.3 or more and 2.2 or less, were able to produce MFI zeolites exhibiting a higher degree of crystallinity.

[0136] It was confirmed by experiments that, from Example 2-1, when the Si / Al ratio was changed to 13.3 and the NSR ratio to 3, the crystallinity was 54.5%, when the heating temperature was changed to 150°C, the Si / Al ratio to 13.3 and the NSR ratio to 2, the crystallinity was 58.6%, and when the heating temperature was changed to 150°C, the Si / Al ratio to 20 and the NSR ratio to 3, the crystallinity was 59.9%. However, in these cases, the impurities in the product were greater than in Examples 2-1 to 2-7.

[0137] Comparative Evaluation of First Production Example and Second Production Example - Figure 5 is a graph comparing the XRD profiles of the zeolite produced in Example 2-1, in which an aging step was performed, and Example 1-2, in which an aging step was not performed. The model peak in Figure 5 is that of the MFI zeolite standard sample IRZ-MFI001 (manufactured by Tosoh Corporation, model number: HSZ-822HOA).

[0138] 5 shows that the peak derived from MFI zeolite is much larger in Example 2-1 than in Example 1-2. That is, it can be seen that, in the method for producing MFI zeolite according to the present disclosure, by carrying out the aging step as in Production Example 2, MFI zeolite exhibiting a higher degree of crystallinity can be produced.

[0139] The embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present disclosure should not be interpreted solely by the above-described embodiments, but should be defined based on the claims. Furthermore, all modifications within the scope and meaning equivalent to the claims are included.

[0140] REFERENCE SIGNS LIST 1 Reaction mother liquor 10 Reaction vessel (hydrothermal furnace) 11 Airtight vessel 12 Screw-on lid of airtight vessel 12a Screw 13 Inner lid of airtight vessel 14 Heat-resistant vessel 15 Lid of heat-resistant vessel 20 Heating device (dryer)

Claims

1. An adding step of adding an aluminum source, a seed crystal of MFI-type zeolite, and sulfuric acid to a solution after artificial crystal growth used for growing artificial crystals by a hydrothermal synthesis method to obtain a reaction mother liquor; and a heating step of heating the reaction mother liquor to produce MFI-type zeolite. A method for producing MFI-type zeolite, characterized by comprising the steps.

2. The method for producing MFI-type zeolite according to claim 1, wherein the solution after artificial crystal growth contains a sodium component, the mass of the sodium component in the solution after artificial crystal growth is A in terms of sodium hydroxide conversion, the mass of sulfuric acid added in the adding step is B, and when the mass ratio A / B is defined as NSR, NSR is 1.5 or more and 7.5 or less. A method for producing MFI-type zeolite, characterized by this.

3. The method for producing MFI-type zeolite according to claim 1, wherein in the adding step, sulfuric acid is added before adding the seed crystal to the solution after artificial crystal growth. A method for producing MFI-type zeolite, characterized by this.

4. The method for producing MFI-type zeolite according to any one of claims 1 to 3, wherein the adding step includes an aging step, and in the aging step, a pre-aging solution obtained by adding at least an aluminum source to the solution after artificial crystal growth is maintained at a predetermined aging temperature to obtain a post-aging solution. A method for producing MFI-type zeolite, characterized by this.

5. The method for producing MFI-type zeolite according to claim 4, wherein the pre-aging solution is obtained by adding an aluminum source and sulfuric acid to the solution after artificial crystal growth. A method for producing MFI-type zeolite, characterized by this.

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