Forjasite-type zeolite and method for producing the same

Abstract

To provide a faujasite-type zeolite which has a large specific surface area with a pore diameter of 7 to 200 nm, has a small proportion of strong acid in the amount of solid acid, and retains high crystallinity.SOLUTION: A faujasite-type zeolite has (a) a molar ratio SiO2 / Al2O3 of 10 to 100, (b) a specific surface area of pores with a pore diameter of 7 to 200 nm, of 25 m2 / g or more, and (c) a strong acid ratio of 23% or less, which is the ratio of an amount of acid at 400 to 550°C to an amount of acid at 100 to 550°C, in an ammonia temperature-programmed desorption method.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a faujasite-type zeolite that has a large specific surface area with a pore diameter of 7 to 200 nm, while maintaining high crystallinity by suppressing crystal collapse, and a method for producing the same. [Background technology]

[0002] The term "zeolite" is a general term for crystalline, porous aluminosilicates. Among zeolites, faujasite-type zeolites, which are porous materials with strong solid acids, have been used for a long time. Furthermore, faujasite-type zeolites have long been used as components of catalysts and adsorbents in the petroleum refining and petrochemical fields.

[0003] The properties of faujasite-type zeolites are known to be greatly influenced by the ratio of Si to Al. This ratio is generally called the Si-Al ratio (SAR) and is expressed as the molar ratio of SiO2 / Al2O3. For example, it is known that increasing this Si-Al ratio reduces the amount of Al in the zeolite framework, thus reducing the solid acids derived from the Al in the framework and resulting in hydrophobicity (low affinity for water). Conversely, decreasing this Si-Al ratio increases the solid acids derived from the Al in the framework, resulting in hydrophilicity.

[0004] Methods for increasing the silica-to-carbon ratio of faujasite-type zeolites are widely known (Patent Documents 1-7). These patent documents report, for example, 1) a method of dealuminization by heat treatment with steam, 2) a method of dealuminization by acid treatment with acid alone or a mixture of acid / ammonium salt, or 3) a combination of two such treatments to obtain zeolites with a very high silica-to-carbon ratio, and some also describe the pH in the acid treatment. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Unexamined Patent Publication No. 60-46916 [Patent Document 2] Japanese Patent Publication No. 60-46917 [Patent Document 3] International Publication No. 2021 / 1210674 [Patent Document 4] Chinese Patent Publication No. 104230633 [Patent Document 5] U.S. Patent No. 5013699 [Patent Document 6] U.S. Patent No. 3,383,169 [Patent Document 7] U.S. Patent No. 5601798 [Overview of the project] [Problems that the invention aims to solve]

[0006] While it is possible to increase the silica-to-carbon ratio of faujasite-type zeolites using the manufacturing method described above, the removal of aluminum from its framework results in a problem where the zeolite crystals collapse, leading to low crystallinity despite having a large pore volume in the mesopore region.

[0007] Given these circumstances, the present invention aims to provide a faujasite-type zeolite that has a large specific surface area in the mesopore region, yet suppresses crystal collapse, thereby reducing the proportion of strong acids in the solid acid content and maintaining high crystallinity. [Means for solving the problem]

[0008] As a result of diligent research to solve the above problems, the inventors discovered that it is possible to obtain a faujasite-type zeolite that has a large specific surface area in the mesopore region, yet suppresses crystal collapse, resulting in a low proportion of strong acids in the solid acid content and high crystallinity.

[0009] The faujasite-type zeolite according to the present invention, which advantageously solves the above problems, [1](a) When the molar ratio of SiO2 / Al2O3 is 10 to 100, (b) pore diameter of 7-200 nm and specific surface area of ​​25 m² 2 / g or more, (c) In the ammonia temperature-controlled desorption method, the strong acid ratio, which is the ratio of the amount of acid at 400-550°C to the amount of acid at 100-550°C, is 23% or less. Furthermore, the faujasite-type zeolite according to the present invention is [2](d) A lattice constant of 24.30 to 24.40 Å is considered to be a more preferable solution.

[0010] Furthermore, the method for producing faujasite-type zeolite according to the present invention, which advantageously solves the above problems, [3] A first step is to obtain an acid-treated zeolite by steam treatment of a faujasite-type zeolite, from which aluminum has been extracted from the zeolite skeleton. The first step involves treating the aforementioned zeolite for acid treatment with an aqueous solution containing an ammonium salt and having a pH in the range of 3.5 to 5.0, followed by steam treatment. The process includes a third step of treating the zeolite obtained in the second step with acid. Furthermore, the method for producing faujasite-type zeolite according to the present invention is as follows: [4] In the second step, it is considered that a more preferable solution would be for the subsequent acid treatment conditions to be such that the temperature is in the range of 50 to 95°C. [Effects of the Invention]

[0011] According to the present invention, a method for producing faujasite-type zeolite is obtained that has a large specific surface area with a pore diameter of 7 to 200 nm, a low proportion of strong acids in the solid acid content, and maintains high crystallinity. Moreover, the faujasite-type zeolite obtained by the method of producing faujasite-type zeolite according to the present invention has high crystallinity, excellent pore distribution and solid acid, and can therefore be suitably used as a component of catalysts or adsorbents used in petroleum refining, petrochemicals, and environmental remediation.

Mode for Carrying Out the Invention

[0012] Hereinafter, the faujasite-type zeolite of the present invention will be described in detail.

[0013] The faujasite-type zeolite of the present invention (hereinafter, also simply referred to as "zeolite") has an increased specific surface area with a pore diameter of 7 to 200 nm while maintaining the crystallinity of the zeolite.

[0014] The zeolite of the present invention is characterized in that (a) the molar ratio of SiO2 / Al2O3 is 10 to 100. Here, the silica-to-alumina ratio of the zeolite is preferably 10 to 100. This silica-to-alumina ratio is calculated from the composition ratio of the zeolite. If the silica-to-alumina ratio is within the above range, it has an appropriate amount of solid acid and is preferably maintained with high crystallinity.

[0015] Furthermore, the specific surface area of the zeolite of the present invention is preferably 600 m 2 / g or more. Zeolites generally have a very large specific surface area due to the pore structure derived from their framework. When the specific surface area of the zeolite is lower than 600 m / g, the pore structure derived from the framework of the zeolite may not be sufficiently developed, and the amount of solid acid may be reduced. The higher the specific surface area of the faujasite-type zeolite, the better, but from the viewpoint of maintaining high crystallinity, the upper limit may be 800 m 2 / g or less. 2

[0016] The zeolite of the present invention is characterized in that (b) the specific surface area with a pore diameter of 7 to 200 nm is 25 m 2 / g or more. That is, the specific surface area with a pore diameter of 7 to 200 nm forming the zeolite of the present invention is preferably 25 m 2 / g or more, and more preferably 28 m 2 / g or more. The specific surface area in the mesopore region is 25 m 2 ​If it is / g or more, crystal collapse can be suppressed, which is preferable because the adsorption ability of the zeolite is improved. On the other hand, the specific surface area of the zeolite of the present invention with a pore diameter of 7 to 200 nm is preferably higher, but from the viewpoint of suppressing crystal collapse, it is 100 m 2 / g or less is preferable. Among them, it is preferable that the specific surface area with a diameter of 7 to 50 nm is higher. The specific surface area of the mesopore region (pore diameter of 7 to 200 nm) can be analyzed by the BJH method using a nitrogen adsorption isotherm showing the relationship between the relative pressure when the adsorbate nitrogen desorbs from the mesopores and the nitrogen adsorption amount.

[0017] The crystallinity of the zeolite of the present invention is preferably higher. The crystallinity of the zeolite affects the durability and solid acid properties of the zeolite. As an index representing the crystallinity of the zeolite, the intensity of the diffraction peak derived from the faujasite structure obtained by X-ray diffraction measurement was used (JIS K0131 General Rules for X-ray Diffraction Analysis). Specifically, a faujasite-type zeolite obtained by a specific method was used as a reference substance, and the intensity ratio of the peak derived from the faujasite structure obtained by X-ray diffraction measurement was used as an index of the crystallinity of the zeolite. The X-ray diffraction intensity ratio of the zeolite is preferably 1.0 or more, and more preferably 1.1 or more. The higher the crystallinity, the more preferable, but the upper limit may be 1.5 or less.

[0018] The zeolite of the present invention is characterized in that in the (c) ammonia temperature-programmed desorption method, the strong acid ratio, which is the ratio of the acid amount at 400 to 550 °C to the acid amount at 100 to 550 °C, is 23% or less. The acid amount of the zeolite of the present invention is preferably 100 to 1200 μmol / g as the NH3 desorption amount at 100 to 550 °C in the ammonia temperature-programmed desorption method (hereinafter also referred to as "NH3-TPD"). If the NH3 desorption amount is less than 100 μmol / g, the zeolite structure may not be sufficiently developed. If the NH3 desorption amount is more than 1200 μmol / g, the cage ratio of the zeolite is low, the lattice constant is high, and the specific surface area of the mesopore region may also become small.

[0019] In the zeolite of the present invention, a low ratio of strong acid sites is preferable. In particular, in NH3-TPD, a low proportion of strong acid sites that desorb at temperatures above 400°C is preferable. In NH3-TPD, the ratio of the amount of acid calculated from the amount of NH3 desorbed at 400-550°C to the amount of acid calculated from the amount of NH3 desorbed at 100-550°C is preferably 23% or less. If the ratio of strong acid sites is greater than 23%, the elution and migration of aluminum outside the zeolite framework may not occur, the surface area of ​​the mesopore region will also be small, and the zeolite of the present invention may not be obtained. On the other hand, if the ratio of strong acid sites is less than 1%, the crystallization of the zeolite may not have progressed sufficiently.

[0020] The lattice constant of the zeolite of the present invention is preferably 24.30 to 24.40 Å. This lattice constant is an indicator of the silica-to-aluminum ratio of the zeolite. When the amount of aluminum in the framework increases (the silica-to-aluminum ratio of the framework decreases), the lattice constant increases, and when the amount of aluminum in the framework decreases (the silica-to-aluminum ratio of the framework increases), the lattice constant decreases. If the lattice constant of the zeolite is too low, there is little aluminum in the framework, so the amount of solid acid tends to decrease. Conversely, if the lattice constant is too high, the amount of solid acid becomes too high.

[0021] The alkali metal content of the zeolite of the present invention is preferably low. Alkali metals can poison the solid acids contained in the zeolite. Therefore, the alkali metal content of the zeolite is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less, when the alkali metal is M, in terms of M2O. The zeolite of the present invention is particularly susceptible to poisoning by Na among alkali metals, so it is preferable to have a low content of Na.

[0022] The zeolite of the present invention can be used, for example, as a component of catalysts used in petroleum refining and petrochemical fields, or as an adsorbent.

[0023] The method for producing the faujasite-type zeolite of the present invention will be described in detail below.

[0024] The present invention provides a method for producing faujasite-type zeolite (hereinafter also referred to as "the production method of the present invention"), which includes a first step of steaming faujasite-type zeolite to obtain acid-treated zeolite from which aluminum has been extracted from the zeolite skeleton; a second step of steaming the acid-treated zeolite with an aqueous solution containing an ammonium salt and having a pH in the range of 3.5 to 5.0; and a third step of acid-treating the zeolite obtained in the second step.

[0025] (First step: Steam treatment) The present invention provides a manufacturing method that includes a step of steam-treating a faujasite-type zeolite to obtain an acid-treated zeolite from which aluminum has been extracted from the zeolite skeleton. In this step, in order to efficiently obtain the acid-treated zeolite, the faujasite-type zeolite may be acid-treated with an aqueous solution containing an ammonium salt before steam-treating. That is, in this step, the ammonium salt contained in the aqueous solution is used to exchange the sodium ions constituting the faujasite-type zeolite for ammonium ions, thereby promoting dealuminization in the subsequent steam treatment and obtaining an acid-treated zeolite from which aluminum has been extracted from the zeolite skeleton.

[0026] The faujasite-type zeolite used in this process may be purchased commercially or synthesized by conventionally known methods. For example, the zeolite can be obtained by adding Si raw materials and Al raw materials, then adding Na raw materials and water, and then performing hydrothermal treatment at a temperature of 80 to 120°C. The silicate ratio of the zeolite used as a raw material is preferably in the range of 3 to 7. Zeolites with a silicate ratio in this range are easy to mass-produce industrially.

[0027] In this process, it is preferable to treat the faujasite-type zeolite, the raw material, with an aqueous solution containing an ammonium salt at a temperature of 50 to 95°C. Treating within this temperature range allows for efficient exchange of sodium ions constituting the zeolite with ammonium ions. Furthermore, the pH of the aqueous solution containing the ammonium salt used in this process is preferably in the range of 6.0 to 7.0.

[0028] Next, this process includes a dealuminization step in which the faujasite-type zeolite, treated with an aqueous solution containing an ammonium salt, is steam-treated to extract aluminum from the zeolite framework. At this time, the extracted aluminum remains as an aluminum compound inside or on the surface of the zeolite crystal. This is also called aluminum outside the zeolite framework. In addition, when aluminum is removed from the zeolite framework, a part of the zeolite collapses, creating voids.

[0029] In this process, it is preferable to steam-treat the faujasite-type zeolite at a temperature of 600 to 800°C. Steam treatment in this temperature range is preferable because it allows for efficient extraction of aluminum from the zeolite framework while suppressing the collapse of the zeolite crystal structure.

[0030] In this process, the steam treatment time is preferably between 1 and 24 hours. Depending on the steam treatment temperature mentioned above, if the treatment time is too short (less than 1 hour), the aluminum may not be sufficiently extracted from the zeolite framework by the steam treatment, which is undesirable. Conversely, extending the steam treatment time beyond 24 hours is also undesirable from a productivity standpoint.

[0031] The steam concentration in this process is 50% or more of the saturated water vapor amount, and preferably 90% or more. If the steam concentration is set to a level lower than 50% of the saturated water vapor amount and steam treatment is performed, the zeolite framework tends to become easily damaged. This is thought to be because defects created when aluminum outside the zeolite framework is formed make the zeolite framework unstable. Therefore, in such a state, the zeolite framework becomes easily damaged by heat. On the other hand, setting the steam concentration within the aforementioned saturated water vapor amount range is preferable because it tends to make the zeolite framework less likely to break.

[0032] The zeolite for acid treatment obtained in this process preferably has a lattice constant of 24.50 to 24.60 Å.

[0033] (Second step: Treatment with an aqueous solution containing ammonium salt) This process includes treating the dealuminized faujasite-type zeolite obtained in the first step with an aqueous solution containing an ammonium salt, followed by steam treatment. In this step, by treating the zeolite obtained in the first step with an aqueous solution containing an ammonium salt and having a pH in the range of 3.5 to 5.0, the aluminum outside the zeolite framework present inside the zeolite crystal is eluted and moved to the outer surface of the zeolite. As a result, in the second step, the growth of aluminum outside the zeolite framework inside the zeolite crystal during the subsequent steam treatment is suppressed, and the diameter of the mesopores in the zeolite after acid treatment is prevented from becoming too large. Consequently, the specific surface area of ​​the mesopore region with a pore diameter of 7 to 200 nm can be increased.

[0034] In this process, it is preferable to treat the dealumininated faujasite-type zeolite obtained in the first step with an aqueous solution containing an ammonium salt having a pH in the range of 3.5 to 5.0. Performing the above acid treatment with an aqueous solution containing an ammonium salt having a pH in this range dissolves the aluminum outside the zeolite framework present inside the zeolite crystal, thereby increasing the specific surface area of ​​the mesopore region formed by the subsequent processing. If the pH of the aqueous solution containing the ammonium salt is too high, it is undesirable because the dissolution and migration of aluminum outside the zeolite framework will not occur. On the other hand, if the pH of the aqueous solution containing the ammonium salt is too low, in addition to the dissolution of aluminum outside the zeolite framework, aluminum inside the zeolite framework will also dissolve, which is undesirable because it leads to a decrease in zeolite crystallinity and a decrease in the amount of acid.

[0035] Examples of ammonium salts used in this process include ammonium sulfate, ammonium nitrate, and ammonium chloride. The ratio of ammonium salt to zeolite is preferably in the range of 1 to 10, where the ratio of moles of ammonium salt to moles of aluminum atoms in the zeolite is between 1 and 10. If this ratio is too low, sodium ions in the zeolite will not be efficiently exchanged. If it is too high, the concentration of ammonium salt in the wastewater will be high, which is industrially undesirable.

[0036] To adjust the pH of an aqueous solution containing an ammonium salt, an appropriate amount of acid is added in addition to the ammonium salt. Conventional known acids can be used as the acid. For example, inorganic acids such as sulfuric acid, nitric acid, and hydrochloric acid can be used.

[0037] In this process, it is preferable to acid-treat the dealumininated faujasite-type zeolite obtained in the first step with an aqueous solution containing an ammonium salt at a temperature of 50 to 95°C. Treating it in this temperature range allows for efficient exchange of sodium ions constituting the faujasite-type zeolite with ammonium ions.

[0038] In this process, the processing time is preferably between 5 minutes and 4 hours. A processing time that is too short is undesirable because it does not allow sufficient elution or migration of aluminum outside the zeolite framework. Conversely, a processing time that is too long is also undesirable from a productivity standpoint.

[0039] (Second step: Steam treatment) The second step includes a dealuminization process in which the faujasite-type zeolite is steam-treated at a temperature of 500-700°C to extract aluminum from the zeolite framework. At this time, the aluminum extracted from the zeolite framework remains as extrazealous aluminum inside or on the surface of the zeolite crystal. In addition, when aluminum is removed from the zeolite, a part of the zeolite disintegrates, creating mesopores.

[0040] In this process, it is preferable to steam-treat the faujasite-type zeolite at a temperature of 500 to 700°C. Steam treatment in this temperature range is preferable because it allows for efficient extraction of aluminum from the zeolite framework, prevents the particle size of aluminum outside the zeolite framework from becoming too large, and increases the specific surface area of ​​the mesopore region after acid treatment.

[0041] In this process, the steam treatment time is preferably between 1 and 24 hours. Depending on the steam treatment temperature mentioned above, a treatment time that is too short is undesirable because it may not be possible to sufficiently extract aluminum from the zeolite framework by steam treatment. Conversely, a steam treatment time that is too long is also undesirable from a productivity standpoint.

[0042] The steam concentration in this process should be 50% or more of the saturated water vapor amount, preferably 90% or more. When steam treatment is performed at a low saturated water vapor amount, the zeolite framework tends to break easily. This is thought to be because defects created when extra-abstract aluminum is formed make the framework unstable. In such a state, the zeolite framework becomes easily damaged by heat. On the other hand, within the aforementioned saturated water vapor amount range, the zeolite framework tends to be less prone to damage.

[0043] The zeolite for acid treatment obtained in this process preferably has a lattice constant of 24.32 to 24.45 Å.

[0044] (Third step: Acid treatment step) The manufacturing method of the present invention includes a step of acid-treating the zeolite obtained in the second step. That is, the manufacturing method of the present invention comprises an acid-treating step in which the zeolite is acid-treated to remove aluminum outside the zeolite framework. In this step, acid is used to remove aluminum outside the zeolite framework that remains inside and on the outer surface of the zeolite crystal after steam treatment. By removing the aluminum outside the zeolite framework that remains inside the zeolite crystal, mesopores having a predetermined pore diameter are formed in the zeolite. The pore diameter (size) of the mesopores is influenced by the particle size of the aluminum outside the zeolite framework.

[0045] In this process, conventionally known acids can be used as the acid. For example, inorganic acids such as sulfuric acid, nitric acid, and hydrochloric acid can be used.

[0046] The temperature of the acid treatment in this process is not particularly limited, but it is preferably in the range of 30 to 98°C.

[0047] The acid treatment time in this process is generally preferably between 0.5 and 24 hours, although this depends on the acid treatment temperature and the amount of acid used. If the acid treatment time is within this range, the objective of the acid treatment process can be fully achieved. While longer acid treatment times are not problematic, they are undesirable from a productivity standpoint.

[0048] After the acid treatment, the acid solution and the zeolite can be separated by solid-liquid separation methods such as filtration. Also, components derived from the acid solution may remain in the separated zeolite at this time. Therefore, it is preferable to perform a washing treatment such as suspending the separated zeolite again in ion-exchanged water and applying warm water at a temperature below 75 °C on a filter cloth.

[0049] The acid treatment step can be repeated two or more times by suspending the zeolite separated after the acid treatment again in ion-exchanged water and adding an acid.

[0050] The zeolite separated after the acid treatment is dried or steam-treated at a temperature of 650 °C or lower to obtain the faujasite-type zeolite of the present invention, which is a super-stabilized Y-type zeolite (hereinafter also referred to as "USY zeolite").

Example

[0051] Hereinafter, examples of the zeolite of the present invention and its production method will be shown and described specifically, but the present invention is not limited to these examples. The measurements and evaluations in the examples of the present invention were performed by the following methods.

[0052] <Composition analysis> For the composition analysis of the zeolite, a fluorescent X-ray measuring device ("RIX-3000" manufactured by Rigaku Corporation) was used. The Si and Al contents were converted into SiO2 and Al2O3, respectively, and the silica-alumina ratio (SiO2 / Al2O3 molar ratio) was calculated.

[0053] <Measurement of X-ray diffraction intensity ratio> The crystal structure of the zeolite was determined by measuring the X-ray diffraction pattern at 2θ = 5 to 50° using an X-ray diffractometer (Rigaku Corporation "RINT-Ultima", radiation source: CuKα). Based on the measurement results, samples showing peaks on diffraction planes attributed to the faujasite structure (FAU) were determined to possess this structure. Specifically, the presence or absence of diffraction peaks attributed to the (331), (511), (440), (533), (642), and (555) planes was confirmed. The positions of these peaks attributed to diffraction planes are referenced in the technical literature (MMJ Treacy, JB Higgins, COLLECTION OF SIMULATED XRD). This can be confirmed in POWDERPATTERNS FOR ZEOLITES, Fifth Revised Edition, Elsevier. Note that the peak position may vary slightly depending on the measurement conditions, so if it is within ±0.5° of the peak position described in the above literature, it can be considered to have a peak originating from the faujasite structure. From the X-ray diffraction patterns obtained in this way, the intensities of the diffraction peaks attributed to the (331), (511), (440), (533), (642), and (555) planes of the faujasite structure (FAU) were summed, and the ratio of this sum to the sum of the peak intensities of the faujasite-type zeolite (JRC-Z-Y5.3), a reference catalyst of the Catalysis Society of Japan, which was measured in the same manner, was calculated to determine the X-ray diffraction intensity ratio.

[0054] <Measurement of lattice constants> The lattice constants of the zeolite were determined using an X-ray diffractometer (Rigaku Corporation's "RINT-Ultima"). The sample used for measurement was a mixture of zeolite powder and TiO2 anatase-type powder (manufactured by Kanto Chemical Co., Ltd., titanium(IV) oxide (anatase type)) as an internal standard, mixed in a 2:1 (weight ratio) in a mortar. Using CuKα radiation, the X-ray diffraction patterns were measured at 2θ = 23 to 33°, and the lattice constants were calculated from the following equations (1) to (3) using the 2θ representing the center of the peak half-width of the (533) and (642) planes of TiO2 anatase-type and faujasite-type zeolites, respectively.

[0055]

Number

[0056] <Measurement of specific surface area> The specific surface area of the zeolite was measured using "MR-6" manufactured by Nippon Bell Co., Ltd. For the zeolite powder pretreated at 500 °C for 1 hour in an inert gas atmosphere, a mixed gas with a nitrogen gas concentration of 30 vol% and a helium gas concentration of 70 vol% was allowed to flow sufficiently in the sample cell for measurement under a -196 °C atmosphere to adsorb nitrogen to the sample powder. Then, the atmosphere temperature was raised to 25 °C, the nitrogen adsorbed to the sample powder was desorbed, and the desorption amount was detected by a TCD (thermal conductivity) detector. By converting the detected nitrogen desorption amount into the specific surface area using the cross-sectional area of nitrogen molecules, the specific surface area per 1 g of the sample powder was determined.

[0057] <Measurement of mesoporous specific surface area> The mesoporous specific surface area was measured using "BEL SORP-miniII" manufactured by MicrotracBEL. For the zeolite powder pretreated at 500 °C for 1 hour in an inert gas atmosphere, pore size distribution measurement by the nitrogen adsorption method was performed in the relative pressure range of 0 to 1.0. From the obtained nitrogen adsorption isotherm, the pore specific surface area of the pore group in the pore diameter range of 7 to 200 nm was calculated by the BJH method and taken as the mesoporous specific surface area.

[0058] <NH3-TPD measurement (evaluation of solid acid amount)> The amount of ammonia desorbed as acid was measured by the ammonia thermal desorption method (NH3-TPD method). Specifically, using a Microtrac-Bel "BELCAT II" analyzer, 0.05 g of the sample was placed in the measurement cell, evacuated at 500°C for 1 hour, then the temperature was reduced to 100°C, and ammonia gas was introduced at 100°C for 0.5 hours for adsorption. Next, after evacuating again at 100°C for 0.5 hours, the temperature was increased from 100°C to 550°C at a rate of 10°C per minute under a flow of 50 ml of He gas per minute, and the amount of ammonia desorbed with increasing temperature was measured. Here, the strong acid ratio (%) is defined as the ratio of the amount of acid in the 400-550°C range to the amount of acid in the entire range of 100-550°C. That is, the strong acid ratio (%) is calculated by the following relationship. Strong acid ratio (%) = Acid amount (400-550℃) / Acid amount (100-550℃) x 100

[0059] [Example 1] (Preparation of faujasite-type zeolite (Zeolite A)) As a NaY-type zeolite, it has an SiO2 / Al2O3 (molar ratio) of 5.1, a lattice constant of 24.66 Å, and a specific surface area of ​​720 m². 2 A NaY-type zeolite with a Na content of 13.0% by mass (based on Na2O) was used. 50 kg of NaY-type zeolite was added to 500 L of 60°C hot water, and then 14 kg of ammonium sulfate was added to obtain a suspension. This suspension was stirred at 70°C for 1 hour and filtered. The solid obtained by filtration was washed with 60°C hot water. Next, this solid was washed with an ammonium sulfate solution prepared by dissolving 14 kg of ammonium sulfate in 500 L of 60°C hot water, and then washed again with 500 L of 60°C water to obtain a washed cake. The obtained washed cake was dried at 130°C for 20 hours, and approximately 65% ​​by mass of the Na contained in the NaY-type zeolite was converted into ammonium ions (NH4). + Y-type zeolite (NH4Y) was obtained by ion exchange using ). The Na content of this NH4Y-type zeolite was 4.5% by mass in terms of Na2O.

[0060] Forty-tenths of this NH4Y-type zeolite was steam-treated at 625°C for one hour in a saturated water vapor atmosphere to obtain a dealumininated faujasite-type zeolite (zeolite A). The obtained zeolite A had a Na content of 4.5% by mass in terms of Na2O, an SiO2 / Al2O3 ratio of 5.1, and a lattice constant of 24.57 Å.

[0061] (Preparation of zeolite for acid treatment (1)) 40 kg of zeolite A was added entirely to 400 L of 60°C hot water, and then 49 kg of ammonium sulfate was added to obtain a suspension. 1.0 kg of 25% by mass sulfuric acid was added to this suspension to adjust the pH to 5.0. The suspension was then heated to 90°C, stirred at 90°C for 1 hour, and filtered. The solid obtained by filtration was washed with 60°C hot water. The solid was then dried at 130°C for 20 hours to obtain zeolite dry powder (1) with a Na2O content of 0.9% by mass and a lattice constant of 24.58 Å. The obtained zeolite dry powder (1) was steam treated at 670°C for 2 hours in a saturated steam atmosphere to obtain zeolite (1) for acid treatment.

[0062] (Preparation of USY zeolite (1)) 2.0 kg of acid-treated zeolite (1) was suspended in 16 L of water at room temperature and the temperature was raised to 75°C. Then, 4.6 kg of 25% by mass sulfuric acid was gradually added, and the mixture was stirred for 4 hours before being filtered. The solid obtained by filtration was washed with 60°C warm water and then dried at 110°C for 20 hours to obtain USY zeolite (1). The properties (physical properties) of USY zeolite (1) are shown in Table 1.

[0063] [Example 2] (Preparation of zeolite (2) for acid treatment) Except for adding 23.0 kg of 25% by mass sulfuric acid to adjust the pH to 3.5, a zeolite dry powder (2) with a Na2O content of 0.8% by mass and a lattice constant of 24.56 Å and an acid-treated zeolite (2) were obtained in the same manner as in Example 1.

[0064] (Preparation of USY zeolite (2)) USY zeolite (2) was obtained in the same manner as in Example 1, except that acid-treated zeolite (2) was used as the zeolite for acid treatment. The properties (physical properties) of USY zeolite (2) are shown in Table 1.

[0065] [Example 3] (Preparation of USY zeolite (3)) USY zeolite (3) was obtained in the same manner as in Example 1, except that 2.0 kg of acid-treated zeolite (1) was suspended in 16 L of water at room temperature, the temperature was raised to 40°C, and then 1.6 kg of 25% by mass sulfuric acid was added. The properties (physical properties) of USY zeolite (3) are shown in Table 1.

[0066] [Example 4] (Preparation of USY zeolite (4)) USY zeolite (4) was obtained in the same manner as in Example 1, except that 2.0 kg of acid-treated zeolite (1) was suspended in 16 L of water at room temperature, the temperature was raised to 90°C, and then 8.0 kg of 25% by mass sulfuric acid was added. The properties (physical properties) of USY zeolite (4) are shown in Table 1.

[0067] [Comparative Example 1] (Preparation of zeolite for acid treatment (3)) Except for not adding 25% by mass sulfuric acid and adjusting the pH to 6.0, a zeolite dry powder (3) with a Na2O content of 1.0% by mass and a lattice constant of 24.58 Å and an acid-treated zeolite (3) were obtained in the same manner as in Example 1.

[0068] (Preparation of USY zeolite (5)) USY zeolite (5) was obtained in the same manner as in Example 1, except that acid-treated zeolite (3) was used as the zeolite for acid treatment. The properties (physical properties) of USY zeolite (5) are shown in Table 1.

[0069] [Comparative Example 2] (Preparation of zeolite for acid treatment (4)) Except for adding 55.8 kg of 25% by mass sulfuric acid to adjust the pH to 2.4, a zeolite dry powder (4) with a Na2O content of 0.8% by mass and a lattice constant of 24.51 Å and an acid-treated zeolite (4) were obtained in the same manner as in Example 1.

[0070] (Preparation of USY zeolite (6)) The only difference from Example 1 is that acid-treated zeolite (4) was used as the acid-treated zeolite. USY zeolite (6) was obtained in the same manner. The properties (physical properties) of USY zeolite (6) are shown in Table 1.

[0071] [Comparative Example 3] (Preparation of zeolite for acid treatment (5)) Zeolite A was suspended in water at room temperature, ammonium sulfate and 23.0 kg of 25% by mass sulfuric acid were added to adjust the pH to 3.5, and then the temperature was raised to 40°C and stirred at 40°C for 1 hour. Except for these steps, the procedure was the same as in Example 2 to obtain a dried zeolite powder (5) with a Na2O content of 0.8% by mass and a lattice constant of 24.56 Å, and a zeolite for acid treatment (5).

[0072] (Preparation of USY zeolite (7)) USY zeolite (7) was obtained in the same manner as in Example 1, except that acid-treated zeolite (5) was used as the zeolite for acid treatment. The properties (physical properties) of USY zeolite (7) are shown in Table 1.

[0073] [Comparative Example 4] (Preparation of faujasite-type zeolite (Zeolite B)) 40 kg of NH4Y-type zeolite prepared in the same manner as in Example 1 was steam-treated at 500°C for 1 hour in a saturated water vapor atmosphere to obtain dealumininated faujasite-type zeolite (zeolite B). The Na content of the obtained zeolite B was 4.5% by mass in terms of Na2O, the SiO2 / Al2O3 ratio was 5.1, and the lattice constant was 24.61 Å.

[0074] (Preparation of zeolite for acid treatment (6)) Except for using zeolite B as the zeolite, a zeolite dry powder (6) with a Na2O content of 0.8 mass% and a lattice constant of 24.62 Å and an acid-treated zeolite (6) were obtained in the same manner as in Example 1.

[0075] (Preparation of USY zeolite (8)) The only difference from Example 1 is that acid-treated zeolite (6) was used as the acid-treated zeolite. Similarly, USY zeolite (8) was obtained. Properties (physical properties) of USY zeolite (8) This is shown in Table 1.

[0076] [Comparative Example 5] (Preparation of faujasite-type zeolite (Zeolite C)) 40 kg of NH4Y-type zeolite prepared in the same manner as in Example 1 was heat-treated at 600°C for 1 hour under air circulation to obtain dealumininated faujasite-type zeolite (zeolite C). The obtained zeolite C had a Na content of 4.5% by mass in terms of Na2O, an SiO2 / Al2O3 ratio of 5.1, and a lattice constant of 24.65 Å.

[0077] (Preparation of zeolite for acid treatment (7)) Except for using zeolite C as the zeolite, a zeolite dry powder (7) with a Na2O content of 0.8 mass% and a lattice constant of 24.66 Å and an acid-treated zeolite (7) were obtained in the same manner as in Example 1.

[0078] (Preparation of USY zeolite (9)) USY zeolite (9) was obtained in the same manner as in Example 1, except that 2.0 kg of acid-treated zeolite (7) was suspended in 16 L of water at room temperature, the temperature was raised to 40°C, and then 1.0 kg of 25% by mass sulfuric acid was added. The properties (physical properties) of USY zeolite (9) are shown in Table 1.

[0079] [Table 1]

[0080] Table 1 shows that USY zeolites (1) to (4) have a certain degree of X-ray diffraction intensity ratio and crystal lattice constant, which indicate the crystallinity of the zeolite, compared to USY zeolites (5) to (9), and also have a larger specific surface area with a pore diameter of 7 to 200 nm.

Claims

1. (a) SiO ２ / Al ２ O ３ The molar ratio is 10 to 100. (b) pore diameter of 7-200 nm and specific surface area of ​​25 m² ２ / g or more, (c) In the ammonia temperature-controlled desorption method, the strong acid ratio, which is the ratio of the amount of acid at 400-550°C to the amount of acid at 100-550°C, (d) The X-ray diffraction intensity ratio of the zeolite is in the range of 1.1 or more and 1.5 or less. Forjasite-type zeolite.

2. The faujasite-type zeolite according to claim 1, wherein the lattice constant is 24.30 to 24.40 Å.

3. The faujasite-type zeolite according to Claim 1 or Claim 2, wherein the pore diameter is 7 to 200 nm and the specific surface area is in the range of 28 m² / g or more and 100 m² / g or less.

4. The first step involves steam treatment of a faujasite-type zeolite to obtain an acid-treated zeolite with a lattice constant in the range of 24.50 to 24.60 Å, from which aluminum has been extracted from the zeolite's framework. The first step involves treating the acid-treated zeolite with an aqueous solution containing an ammonium salt and having a pH in the range of 3.5 to 5.0 at a temperature range of 50 to 95°C, followed by steam treatment. A method for producing faujasite-type zeolite, comprising a third step of acid-treating the zeolite obtained in the second step.

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