Copper-containing FAU type zeolite

Abstract

To provide at least one of a copper-containing FAU zeolite exhibiting high hydrocarbon purification performance and a method for producing the same.SOLUTION: A copper-containing FAU zeolite has a lattice constant of 24.370 Å to 24.490 Å inclusive, a bulk SAR of 10 to 20 inclusive, and an Al ratio in the framework of 70% to 100% inclusive.SELECTED DRAWING: None

Description

[Technical Field]

[0001] Exhaust gases emitted from internal combustion engines used in mobile vehicles such as automobiles and ships contain a large amount of hydrocarbons, and these hydrocarbons are purified by a three-way catalytic converter. However, since a temperature environment of 200°C or higher is required for the three-way catalytic converter to function, in temperature ranges where the three-way catalytic converter does not function, such as during a cold start, hydrocarbons are adsorbed onto a hydrocarbon adsorbent. When the temperature range in which the three-way catalytic converter begins to function is reached, the hydrocarbons are released from the adsorbent and decomposed and purified by the three-way catalytic converter.

[0002] Automobile exhaust gas temperatures can reach over 900°C depending on engine operating conditions. Furthermore, the exhaust gas composition changes depending on the operating conditions. Therefore, hydrocarbon adsorbents require heat resistance.

[0003] As a method for adsorbing and purifying hydrocarbons from exhaust gas at low temperatures, the use of hydrocarbon adsorbents such as zeolites is known. Patent Document 1 describes that a copper-containing FAU-type zeolite exhibits high hydrocarbon adsorption properties even after exposure to a high-temperature, high-humidity reducing atmosphere. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-150822 [Overview of the project] [Problems that the invention aims to solve]

[0005] Recently, there has been a demand for zeolites that exhibit higher hydrocarbon purification performance. This disclosure aims to provide at least one of the following: a copper-containing FAU-type zeolite exhibiting high hydrocarbon purification performance and a method for producing the same. [Means for solving the problem]

[0006] The inventors have discovered a copper-containing FAU-type zeolite that exhibits superior hydrocarbon adsorption performance compared to conventional zeolites, and a method for producing the same.

[0007] In other words, the present invention is as described in the claims, and the gist of this disclosure is as follows: [1] A copper-containing FAU-type zeolite having a lattice constant of 24.370 Å or more and 24.490 Å or less, a bulk SAR of 10 or more and 20 or less, and an Al ratio within the framework of 70% or more and 100% or less. [2] The copper-containing FAU type zeolite described in [1] above, wherein the copper content is 0.5% by mass or more and 5.0% by mass or less. [3] The copper-containing FAU type zeolite according to [1] or [2], wherein the alkali metal content is 0% by mass or more and 0.15% by mass or less. [4] The copper-containing FAU type zeolite described in [1] to [3] above, wherein the average crystal diameter is 0.5 μm or more and 2.0 μm or less. [5] BET specific surface area is 300m 2 / g or more 1500m 2 A copper-containing FAU type zeolite according to [1] to [4] above, wherein the amount is less than or equal to / g and the micropore volume is 0.20 mL / g or more and 0.70 mL / g or less. [6] A method for producing copper-containing FAU-type zeolite, comprising: a firing step of firing a raw material FAU-type zeolite having an alkali metal content of 0% by mass or more and 0.20% by mass or less in an air atmosphere containing 3% by volume or more and 10% by volume or less of water vapor; and an acid treatment step of contacting the zeolite firing body obtained in the firing step with an acid. [7] A method for producing copper-containing FAU-type zeolite according to [6], wherein the lattice constant of the raw material FAU-type zeolite is 24.350 Å or more and 24.550 Å or less, the firing temperature in the firing step is 500°C or more and 800°C or less, and the acid in the acid treatment step is hydrochloric acid. [8] A method for producing copper-containing FAU type zeolite according to [7], wherein in the acid treatment step, the zeolite calcined body is brought into contact with hydrochloric acid such that the mass ratio of hydrogen chloride to the zeolite calcined body is 0.035 or more and 0.600 or less.

Advantages of the Invention

[0008] According to the present disclosure, it is possible to provide a copper-supported FAU-type zeolite exhibiting high hydrocarbon adsorption characteristics.

Modes for Carrying Out the Invention

[0009] Hereinafter, an example of an embodiment of the present disclosure will be shown and described. The terms in this embodiment are as follows.

[0010] "Aluminosilicate" is a composite oxide having a structure composed of a network of aluminum (Al) and silicon (Si) via oxygen (O). Among aluminosilicates, those having crystalline XRD peaks in their powder X-ray diffraction (hereinafter also referred to as "XRD") patterns are "crystalline aluminosilicates", and those not having crystalline XRD peaks are "amorphous aluminosilicates".

[0011] In this embodiment, examples of the XRD pattern include those obtained from XRD measurements under the following conditions.

[0012] Accelerating current and voltage: 40 mA·40 kV X-ray source: CuKα ray (λ = 1.5405 Å) Measurement mode: Step scan Scan condition: 40° / min Measurement time: 3 s Measurement range: 2θ = 3° to 43° Divergence vertical limit slit: 10 mm Divergence / incidence slit: 1° Receiving slit: open Receiving solar slit: 5° Detector: Semiconductor detector (D / teX Ultra) Filter: Ni filter XRD patterns can be measured using a general powder X-ray diffractometer (e.g., Ultima IV Protectus, manufactured by Rigaku Corporation). Crystalline XRD peaks are peaks whose peak top 2θ is identified and detected in the analysis of the XRD pattern using general analysis software, and examples include XRD peaks with a full width at half maximum of 2θ = 0.50° or less.

[0013] A "zeolite" is a compound in which the skeletal atoms (hereinafter also referred to as "T atoms") have a regular structure mediated by oxygen (O), and the T atoms consist of at least one of a metal atom and / or a metalloid atom. Examples of metal atoms include one or more selected from the group consisting of aluminum (Al), titanium (Ti), iron (Fe), zinc (Zn), gallium (Ga), and tin (Sn). Examples of metalloid atoms include at least one selected from the group consisting of boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), and tellurium (Te).

[0014] A "zeolite-like substance" is a compound in which the T atom has a regular structure mediated by oxygen, and which contains at least one atom other than a metal or metalloid in the T atom. Examples of zeolite-like substances include aluminophosphate (AlPO) and silicoaluminophosphate (SAPO), which are complex phosphorus compounds containing phosphorus (P) as the T atom. "Zeolite-like substances" are distinct from "zeolites."

[0015] The "regular structure" (hereinafter also referred to as "zeolite structure") in zeolites and zeolite-like materials is a skeletal structure specified by the skeletal code (hereinafter also referred to as "skeletal code") defined by the Structure Commission of the International Zeolite Association (hereinafter also simply referred to as "IZA"). For example, "FAU-type zeolite" is a zeolite having a skeletal structure specified by the structural code "FAU". The skeletal structure of a zeolite can be identified by comparing the XRD pattern (hereinafter also referred to as "reference pattern") of each zeolite structure described in Collection of simulated XRD powder patterns for zeolites, Fifth revised edition (2007) with the XRD pattern of the zeolite in question. With respect to zeolite structures, skeletal structure, crystalline structure, and crystalline phase are used synonymously.

[0016] "Copper-containing zeolite" refers to zeolite that contains the element copper. The state of the contained copper element is not particularly limited; for example, it may be at least one state selected from the group of metals, ions, and compounds. Whether a zeolite contains the element copper can be determined by detecting the element copper through elemental analysis such as ICP.

[0017] "Bulk SAR" is the ratio of the number of moles [mol] of silicon (Si) contained in the bulk material of zeolite (calculated as SiO2) to the number of moles [mol] of aluminum (Al) contained in the bulk material of zeolite (hereinafter also referred to as "bulk Al"), calculated as Al2O3.

[0018] "Skeletal SAR" is the ratio of the number of moles [mol] of silicon (Si) contained in the bulk material of the zeolite, converted to SiO2, to the number of moles [mol] of aluminum atoms present as T atoms in the zeolite (hereinafter also referred to as "infrastructure Al") converted to Al2O3. It can be calculated using the Engelhardt formula described in "Crystal Research and Technology, 1984, Vol. 19, No. 1, pp. K1-K3".

[0019] Skeletal SAR =((192 / (112.4×(Lattice constant (Å)-24.233)))-1)×2 The "intraskeletal Al ratio" is the ratio of the amount of Al within the skeleton to the amount of Al in the bulk, and can be calculated using the following formula.

[0020] Intraskeletal Al ratio [%] = (Bulk SAR / Skeletal SAR) × 100 "Extra-skeleton Al" refers to aluminum atoms that exist in the bulk Al of zeolite other than the T atoms.

[0021] A "zeolite slurry" is a liquid containing zeolite and a solvent, and is fluid in nature.

[0022] "Solid content concentration" is the ratio of the mass of zeolite to the total mass of the zeolite slurry, and can be calculated using the following formula.

[0023] Solid content concentration (mass%) = (Zeolite mass (g) / Zeolite slurry mass (g)) × 100 The mass of the zeolite slurry is the value obtained by measuring the mass of the zeolite slurry, and the zeolite mass is the mass of the solid content obtained by drying the zeolite slurry after the mass measurement and treating it at 600°C in air.

[0024] The copper-containing FAU-type zeolite of this embodiment will be described below.

[0025] The copper-containing FAU zeolite of the present embodiment is a copper-containing FAU zeolite having a lattice constant of 24.370 Å or more and 24.490 Å or less, a bulk SAR of 10 or more and 20 or less, and an in-frame Al ratio of 70% or more and 100% or less.

[0026] The copper-containing FAU zeolite of the present embodiment contains copper. The copper-containing FAU zeolite has an improved hydrocarbon retention capacity compared to a copper-free FAU zeolite. Most of the hydrocarbons adsorbed on the copper-free FAU zeolite are easily released from the FAU zeolite again. In contrast, when the FAU zeolite contains copper, the interaction between the hydrocarbon and the FAU zeolite becomes stronger, and the adsorbed hydrocarbon is less likely to be released from the FAU zeolite.

[0027] In the present embodiment, the copper content of the copper-containing FAU zeolite is preferably 0.5% by mass or more, 1.2% by mass or more, more preferably 1.7% by mass or more, or 2.2% by mass or more, and 5.0% by mass or less, 4.0% by mass or less, 3.5% by mass or less, or 3.0% by mass or less.

[0028] In the present embodiment, the copper content of the copper-containing FAU zeolite is the mass ratio of copper to the mass of the metal and metalloid elements contained in the copper-containing FAU zeolite in terms of oxides. For example, the copper content of a copper-containing FAU zeolite containing copper (Cu) and an alkali metal (M) can be determined from the following formula.

[0029] Copper content (% by mass) = W’ Cu / (W Al + W Si + W M + W Cu ) × 100 In the above formula, W’ Cu is the mass of copper (Cu). W Al , W Si , W M and W Cu are the masses of aluminum (Al) in terms of oxide (Al2O3), W Si is the mass of silicon (Si) in terms of oxide (SiO2), WM This is the mass of alkali metals (M) converted to oxides (M2O), and W Cu This is the mass of copper converted to its oxide (CuO) equivalent.

[0030] The copper-containing FAU-type zeolite of this embodiment has a lattice constant of 24.370 Å or more and 24.490 Å or less. In copper-containing FAU-type zeolites with a lattice constant of less than 24.370 Å, the interaction between aluminum and copper, which constitute the framework of the crystal structure, is weak. As a result, copper aggregation is likely to occur upon exposure to a high-temperature, high-humidity atmosphere. Consequently, the hydrocarbon adsorption properties deteriorate significantly after exposure to a high-temperature, high-humidity atmosphere. When the lattice constant exceeds 24.490 Å, the heat resistance of the framework structure of the copper-containing FAU-type zeolite decreases, and therefore the hydrocarbon adsorption properties deteriorate after exposure to a high-temperature, high-humidity atmosphere.

[0031] In this embodiment, the copper-containing FAU-type zeolite preferably has a lattice constant of 24.370 Å or higher, 24.390 Å or higher, and 24.490 Å or lower, or 24.470 Å or lower.

[0032] The lattice constant of the copper-containing FAU-type zeolite in this embodiment can be determined using a general X-ray diffractometer (e.g., Ultima IV Protectus, manufactured by Rigaku Corporation) and the resulting XRD pattern, by a lattice constant measurement method compliant with ASTM D3942-80 ("Standard Test Method for Determination of the Unit Cell Dimension of a Faujasite-Type Zeolite").

[0033] In this embodiment, the bulk SAR of the copper-containing FAU-type zeolite is 10 or more and 20 or less. If the bulk SAR is less than 10, there is an excess of extraskeletal Al, which interferes with the contact between copper and hydrocarbons, thus reducing the hydrocarbon adsorption properties. If the bulk SAR exceeds 20, the crystallinity of the copper-containing FAU-type zeolite decreases, and the hydrocarbon adsorption properties also decrease. In this embodiment, the bulk SAR of the copper-containing FAU-type zeolite is preferably 11 or more, or 12 or more, and preferably 18 or less, or 16 or less.

[0034] In this embodiment, the Al ratio within the framework of the copper-containing FAU-type zeolite is 70% to 100%. If the Al ratio within the framework is less than 70%, there is an excess of Al outside the framework, which interferes with the contact between copper and hydrocarbons, thus reducing the hydrocarbon adsorption properties.

[0035] The copper-containing FAU-type zeolite of this embodiment exhibits high hydrocarbon adsorption characteristics by having a bulk SAR of 10 to 20 and an Al ratio within the skeleton of 70% to 100%.

[0036] In this embodiment, the copper-containing FAU-type zeolite may contain alkali metals (i.e., the alkali metal content may exceed 0% by mass), but it is preferable that the alkali metal content is 0.15% by mass or less. As a result, the copper-containing FAU-type zeolite of this embodiment tends to exhibit high hydrocarbon adsorption characteristics even after exposure to a high-temperature, high-humidity atmosphere. The alkali metal content is preferably 0% by mass or more and 0.15% by mass or less, more preferably 0% by mass or more and 0.10% by mass or less, and even more preferably 0% by mass or more and 0.07% by mass or less.

[0037] In this embodiment, the alkali metal content of the copper-containing FAU-type zeolite is the ratio of the mass of alkali metals (in oxide equivalent) to the mass of metals (in oxide equivalent) contained in the copper-containing FAU-type zeolite. For example, the alkali metal content of a copper-containing FAU-type zeolite containing copper (Cu) and alkali metals (M) can be calculated using the following formula.

[0038] Alkali metal content (mass %) = W M / (W Al +W Si +W M +W Cu ) × 100 For example, if the alkali metal is sodium, the alkali metal content is also called the Na2O content.

[0039] In this embodiment, the alkali metal contained in the copper-containing FAU-type zeolite is, for example, at least one of potassium (K) and sodium (Na), and preferably the alkali metal is sodium.

[0040] The copper-containing FAU-type zeolite of this embodiment may contain transition metals other than copper when used as a catalyst or adsorbent. Preferred transition metals to be contained in the copper-containing FAU-type zeolite of this embodiment include at least one from the group consisting of groups 8, 9, 10, and 11 of the periodic table, and one or more from the group consisting of platinum (Pt), palladium (Pd), rhodium (Rh), silver (Ag), iron (Fe), cobalt (Co), manganese (Mn), and indium (In).

[0041] In this embodiment, the average crystal diameter of the copper-containing FAU-type zeolite is 0.5 μm or more and 2.0 μm or less. From the viewpoint of improving operability such as applicability to the adsorbent carrier, the average crystal diameter of the copper-containing FAU-type zeolite is preferably 0.6 μm or more and 1.5 μm or less, and more preferably 0.65 μm or more and 1.0 μm or less.

[0042] In this embodiment, the average crystal diameter is the average particle diameter of the primary particles. The particle diameter of the primary particles is the particle diameter of the primary particles confirmed in the SEM observation image obtained by scanning electron microscope (hereinafter also referred to as "SEM") observation, and the average crystal diameter is the average value of the particle diameters of the primary particles. One method for measuring the average crystal diameter is to measure the particle diameters of 80 to 150 primary particles observed at a magnification of 3,000 to 20,000 times, and use the average value as the average crystal diameter. For particle diameter measurement, an SEM observation image of 1 or more is sufficient.

[0043] In this embodiment, the primary particles of the copper-containing FAU-type zeolite are particles that can be observed as independent particles under SEM observation at magnifications of 3,000 to 20,000 times.

[0044] In this embodiment, the copper-containing FAU-type zeolite has a BET specific surface area of ​​300 m².2 / g or more, 500m 2 / g or more or 700m 2 It is 1500m or more 2 / g or less, 1000m 2 / g or less or 900m 2 It is preferable that the amount is less than or equal to / g.

[0045] The BET specific surface area can be determined by a single-point BET method using a nitrogen adsorption method in accordance with JIS Z8830:2013, using a general nitrogen adsorption apparatus (e.g., BELSORP-mini II, manufactured by Microtrac-Bel). Nitrogen adsorption should be measured on the sample after pretreatment. The pretreatment conditions and nitrogen adsorption conditions are shown below.

[0046] Measurement method: constant volume method Measurement temperature: 77K (-196℃) Pretreatment: Vacuum drying at 350°C for 2 hours In this embodiment, the copper-containing FAU-type zeolite preferably has a pore volume of 2 nm or less in diameter when approximated as a cylinder (hereinafter also referred to as "micropore volume") of 0.20 mL / g or more, 0.25 mL / g or more, or 0.30 mL / g or more, and more preferably 0.70 mL / g or less, 0.50 mL / g or less, or 0.40 mL / g or less.

[0047] The micropore volume can be determined by performing a t-plot analysis on nitrogen adsorption isotherms, which are obtained in a similar manner to the measurement of the BET specific surface area. The t-plot analysis can be performed under the following conditions, and the analysis can be performed using the analysis software provided with the nitrogen adsorption device (e.g., BELMASTER, manufactured by Microtrac-Bel).

[0048] Adsorbate cross section: 0.162nm 2 Saturated water vapor pressure: 103.72 kPa First straight line: A straight line connecting the point at t=0nm and the point at t=0.27±0.03nm. Second line: A line connecting the points at t=0.80±0.10nm and t=1.00±0.10nm. In this embodiment, the copper-containing FAU-type zeolite may contain a binder. Examples of binders include at least one selected from the group consisting of silica, alumina, kaolin, attapulgite, montmorillonite, bentonite, alloene, and sepiolite.

[0049] In this embodiment, copper-containing FAU-type zeolite can be used in a hydrocarbon adsorption method, preferably in a hydrocarbon adsorption method in an environment where the hydrocarbon adsorbent is exposed to high temperatures, more preferably in a hydrocarbon adsorption method from exhaust gas of an internal combustion engine, and even more preferably in a hydrocarbon adsorption method from exhaust gas of a mobile internal combustion engine.

[0050] The copper-containing FAU-type zeolite of this embodiment can be used as a solid acid catalyst, a metal catalyst support, or a hydrocarbon adsorbent.

[0051] The copper-containing FAU-type zeolite of this embodiment may be used as a hydrocarbon adsorbent containing it, or it may be a hydrocarbon adsorbent consisting solely of the copper-containing FAU-type zeolite of this embodiment.

[0052] In this embodiment, the hydrocarbon adsorbent can be used in a hydrocarbon adsorption method by a method comprising a step of contacting a hydrocarbon-containing gas with a hydrocarbon-containing adsorbent containing copper-containing FAU-type zeolite (hereinafter also referred to as the "contact step").

[0053] In the contact process, the form of the hydrocarbon adsorbent containing copper-containing FAU-type zeolite is arbitrary and can be at least one of powder or molded body.

[0054] When the hydrocarbon adsorbent containing copper-containing FAU-type zeolite is in powder form, a slurry containing the hydrocarbon adsorbent containing copper-containing FAU-type zeolite can be applied to a substrate and used as an adsorbent material. When the hydrocarbon adsorbent containing copper-containing FAU-type zeolite is in molded form, it can be used in any shape by any molding method, such as at least one selected from the group consisting of rolling granulation, press molding, extrusion molding, injection molding, casting, and sheet molding. Examples of molded shapes include at least one selected from the group consisting of spherical, substantially spherical, elliptical, disc-shaped, cylindrical, polyhedral, irregular shape, and petal-shaped.

[0055] The hydrocarbon adsorbent containing copper-containing FAU-type zeolite according to this embodiment can be used in hydrocarbon adsorption methods.

[0056] The hydrocarbon adsorbent containing copper-containing FAU-type zeolite of this embodiment can adsorb hydrocarbons by a method that includes a step of contacting a hydrocarbon-containing fluid with the hydrocarbon adsorbent of this embodiment.

[0057] Examples of hydrocarbon-containing fluids include hydrocarbon-containing gases and hydrocarbon-containing liquids.

[0058] A hydrocarbon-containing gas is a gas containing at least one hydrocarbon, and preferably contains two or more hydrocarbons. The hydrocarbons contained in the hydrocarbon-containing gas include at least one selected from the group consisting of paraffins, olefins, and aromatic hydrocarbons. The number of carbon atoms in the hydrocarbon may be 1 or more, and preferably 1 to 15. The hydrocarbons contained in the hydrocarbon-containing gas are preferably at least two selected from the group consisting of methane, ethane, ethylene, propylene, butane, linear paraffins with 5 or more carbon atoms, linear olefins with 5 or more carbon atoms, benzene, toluene, and xylene, more preferably at least two selected from the group consisting of methane, ethane, ethylene, propylene, butane, benzene, toluene, and xylene, and even more preferably at least one selected from the group consisting of methane, ethane, ethylene, and propylene, and at least one selected from the group consisting of benzene, toluene, and xylene. The hydrocarbon-containing gas may also contain at least one selected from the group consisting of carbon monoxide, carbon dioxide, hydrogen, oxygen, nitrogen, nitrogen oxides, sulfur oxides, and water. Specific examples of hydrocarbon-containing gases include combustion gases such as exhaust gas from internal combustion engines.

[0059] Preferably, the contact temperature between the hydrocarbon-containing fluid and the hydrocarbon adsorbent containing the copper-containing FAU-type zeolite of this embodiment in the process is room temperature to 200°C.

[0060] Next, we will explain the method for producing copper-containing FAU-type zeolite.

[0061] The method for producing copper-containing FAU-type zeolite according to this embodiment includes a firing step of firing raw material FAU-type zeolite having an alkali metal content of 0% by mass or more and 0.20% by mass or less in an air atmosphere containing 3% by volume or more and 10% by volume or less of water vapor, and an acid treatment step of contacting the zeolite firing body obtained in the firing step with an acid.

[0062] The alkali metal content of the raw material FAU-type zeolite is 0% by mass or more and 0.20% by mass or less. If the alkali metal content of the raw material FAU-type zeolite exceeds 0.20% by mass, the lattice constant will decrease excessively due to calcination. Preferably, the alkali metal content of the raw material FAU-type zeolite is 0.01% by mass or more, or 0.02% by mass or more, and also 0.15% by mass or less, or 0.10% by mass or less.

[0063] The alkali metal content of the raw material FAU-type zeolite is the ratio of the mass of alkali metals (in oxide form) to the mass of other metals (in oxide form) contained in the raw material FAU-type zeolite, and can be calculated using the following formula.

[0064] Alkali metal content [mass%] of raw material FAU-type zeolite =W M / (W Al +W Si +W M ) × 100 The alkali metal contained in the raw material FAU-type zeolite is, for example, at least one of potassium (K) and sodium (Na), and preferably the alkali metal is sodium.

[0065] The lattice constant of the raw material FAU-type zeolite is preferably 24.450 Å or higher or 24.480 Å or higher, and preferably 24.600 Å or lower or 24.550 Å or lower.

[0066] The cation type of the raw material FAU-type zeolite can be one or more selected from the group consisting of sodium ion type, hydrogen ion type, and ammonium ion type. Examples of combinations of cation types for the raw material FAU-type zeolite include hydrogen ion and sodium ion type, and ammonium and sodium type.

[0067] The method for producing copper-containing FAU-type zeolite according to this embodiment includes a firing step (hereinafter also simply referred to as the "firing step") in which the raw material FAU-type zeolite is fired in an atmosphere of air containing 3% to 10% by volume of water vapor (hereinafter also referred to as "steam").

[0068] The steam vapor concentration in the firing process is 3% to 10% by volume, preferably 3.5% to 9% by volume, and more preferably 4% to 8% by volume, in order to adjust the lattice constant of the FAU-type zeolite to a favorable range.

[0069] In the firing process, the firing temperature is 400°C to 900°C, preferably 500°C to 800°C, and more preferably 600°C to 750°C.

[0070] The firing time is arbitrary, but preferably between 30 minutes and 10 hours, and more preferably between 1 hour and 5 hours.

[0071] The method for producing copper-containing FAU-type zeolite according to this embodiment includes an acid treatment step (hereinafter simply referred to as the "acid treatment step") in which the FAU-type zeolite obtained in the calcination step (hereinafter also referred to as the "calcined zeolite") is brought into contact with an acid. The acid treatment step causes Al present outside the zeolite skeleton in the calcined zeolite to dissolve into the liquid phase, increasing the bulk SAR of the copper-containing FAU-type zeolite and increasing the Al ratio within the skeleton.

[0072] In the acid treatment step, the acid brought into contact with the calcined zeolite body is preferably hydrochloric acid.

[0073] In the acid treatment step, it is preferable to contact the calcined zeolite body with hydrochloric acid so that the mass ratio of hydrogen chloride to the calcined zeolite body (hereinafter also referred to as the "HCl / zeolite mass ratio") is 0.035 or more and 0.600 or less. The higher the HCl / zeolite mass ratio, the more likely the bulk SAR of the FAU-type zeolite is to be high, and the lower the HCl / zeolite mass ratio, the more likely the bulk SAR of the FAU-type zeolite is to be low. If the HCl / zeolite mass ratio is too high, not only Al outside the framework but also Al inside the framework will dissolve, and the crystallinity of the FAU-type zeolite will decrease. It is preferable that the HCl / zeolite mass ratio is 0.070 or more or 0.100 or more, and 0.350 or less or 0.280 or less.

[0074] In the acid treatment process, the method of contacting the calcined zeolite with the acid is optional, but one method is to mix the calcined zeolite with hydrochloric acid and stir at a temperature of 40°C to 100°C, preferably 50°C to 80°C. The higher the treatment temperature, the more likely the bulk SAR of the FAU-type zeolite will be to increase, and the lower the treatment temperature, the more likely the bulk SAR of the FAU-type zeolite will be to decrease.

[0075] In the acid treatment process, the solid content concentration of the zeolite calcined body and the zeolite slurry containing acid is arbitrary, but is preferably 5% by mass or more and 40% by mass or less, and more preferably 15% by mass or more and 35% by mass or less.

[0076] The concentration of hydrochloric acid used as a raw material in the acid treatment process is arbitrary, but 15% by mass or less and 40% by mass or less is preferred.

[0077] It is preferable that the bulk SAR of the FAU-type zeolite obtained by the acid treatment process (hereinafter also referred to as "zeolite acid-treated body") is higher than the bulk SAR of the calcined zeolite body.

[0078] The method for producing the copper-containing FAU type zeolite of this embodiment preferably includes a metal-containing step (hereinafter also simply referred to as the "metal-containing step") in which a zeolite-treated body is brought into contact with a copper source. Through this metal-containing step, copper is incorporated into the zeolite-treated body, and the copper-containing FAU type zeolite of this embodiment can be obtained.

[0079] The lattice constant of the zeolite acid-treated body subjected to the metal-containing process is not particularly limited, but it is preferably 24.350 Å to 24.520 Å, and more preferably 24.370 Å to 24.490 Å, in order to easily obtain the lattice constant of the copper-containing FAU type zeolite of this embodiment described above in the metal-containing process.

[0080] The copper source is a compound containing copper (Cu), preferably a copper salt, more preferably at least one selected from the group consisting of copper-containing nitrates, sulfates, acetates, chlorides, complex salts, oxides, and composite oxides, and even more preferably at least one selected from the group consisting of copper nitrate, copper sulfate, and copper acetate.

[0081] A known method can be used for contacting the zeolite-treated body with the copper source, and includes at least one selected from the group consisting of ion exchange, impregnation, evaporation to dryness, precipitation, and physical mixing. At least one of the ion exchange or impregnation method is preferred, and the impregnation method is more preferred.

[0082] The copper-containing FAU-type zeolite obtained in the metal-containing process is preferably calcined to remove any remaining salts.

[0083] The firing conditions are arbitrary, but the following conditions can be listed.

[0084] Firing atmosphere: Oxidizing atmosphere, preferably in air. Firing temperature: 400℃ to 600℃ Baking time: 30 minutes to 5 hours In addition to the steps described above, the manufacturing method of this embodiment may also include an alkali removal step, a washing step, a drying step, a washing step after the metal-containing step, and a drying step after the metal-containing step.

[0085] The alkali removal step removes alkali metals contained in the copper-containing FAU-type zeolite after the acid treatment step. These alkali metals originate from components contained in the raw material FAU-type zeolite. Examples of alkali removal methods include one or more selected from the group consisting of liquid-phase treatment with an electrolyte solution, replacement treatment with resin, thermal decomposition treatment, and calcination treatment. Preferably, liquid-phase treatment with an electrolyte solution (e.g., aqueous solution of ammonium chloride) is used.

[0086] The washing step involves solid-liquid separation of the copper-containing FAU-type zeolite and the liquid phase after the acid treatment or alkali removal step. The washing step can be performed by solid-liquid separation using a known method, and the copper-containing FAU-type zeolite obtained as a solid phase can be washed with pure water.

[0087] The drying process removes moisture physically adsorbed onto the copper-containing FAU-type zeolite after the washing process. The drying conditions are arbitrary, but examples include leaving the FAU-type zeolite standing in the air at a temperature of 50°C to 250°C for 1 to 120 hours, or drying it with a spray dryer.

[0088] In the manufacturing method of this embodiment, the water content of the FAU-type zeolite used as a raw material in each step is arbitrary, but examples include 3% by mass or more and 25% by mass or less, preferably 5% by mass or more and 15% by mass or less. [Examples]

[0089] The embodiments will be described in more detail below in the following examples. However, the embodiments are not limited to these examples.

[0090] (Identification of crystal structure) XRD measurements of the sample were performed using a standard X-ray diffractometer (instrument name: UltimaIV Protectus, manufactured by Rigaku Corporation). The measurement conditions were as follows:

[0091] Acceleration current / voltage: 40mA / 40kV Radiation source: CuKα radiation (λ=1.5405Å) Measurement mode: Continuous scan Scanning conditions: 40° / min Measurement range: 2θ = 3° to 43° Divergence vertical limiting slit: 10mm Divergence / Induction Slit: 1° Light-receiving slit: open Solar light receiving slit: 5° Detector: Semiconductor detector (D / teX Ultra) Filter: Ni filter The zeolite structure was identified by comparing the obtained XRD pattern with a reference pattern.

[0092] (Measurement of lattice constants) XRD measurements of the sample were performed using a standard X-ray diffractometer (instrument name: UltimaIV Protectus, manufactured by Rigaku Corporation). The measurement conditions were as follows:

[0093] Acceleration current / voltage: 40mA / 40kV Radiation source: CuKα radiation (λ=1.5405Å) Measurement mode: Continuous scan Scanning conditions: 1° / min Measurement range: 2θ = 52° to 60° Divergence vertical limiting slit: 5mm Divergence / Induction Slit: 2° Light-receiving slit: open Detector: D / teX Ultra Nifilter used Using the obtained XRD patterns, the lattice constant (Å) of the sample was determined by a lattice constant measurement method compliant with ASTM D3942-80 ("Standard Test Method for Determination of the Unit Cell Dimension of a Faujasite-Type Zeolite").

[0094] (composition analysis) A clear sample solution was prepared by dissolving 2 mg of the sample in 10 mL of an aqueous solution (HF: 0.96% by mass, HNO3: 1.2% by mass) prepared by mixing and diluting hydrofluoric acid (HF: 48% by mass) and nitric acid (HNO3: 60% by mass) with pure water. The sample solution was measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES) using a general ICP instrument (instrument name: OPTIMA5300DV, PerkinElmer). From the obtained Si, Al, Na, and Cu measurements, the bulk SAR, copper content, and alkali metal content (Na2O content) of the sample were determined.

[0095] (Calculation of Al ratio within the skeleton) The Al ratio within the sample skeleton was calculated using the following formula.

[0096] Intraskeletal Al ratio [%] = (Bulk SAR / Skeletal SAR) × 100 The skeletal SAR was calculated using the following formula.

[0097] Skeletal SAR =((192 / (112.4×(Lattice constant (Å)-24.233)))-1)×2 (Measurement of BET specific surface area and micropore volume) The sample was degassed at 350°C for 2 hours as a pretreatment. After pretreatment, the nitrogen adsorption isotherm at a measurement temperature of 77K was measured using a standard nitrogen adsorption apparatus (apparatus name: BELSORP-mini II, manufactured by MicrotracBEL). The BET specific surface area of ​​the sample was determined by applying the BET method to the nitrogen gas adsorption results.

[0098] Furthermore, the micropore volume was determined by applying the t-plot method to the nitrogen gas adsorption results. The t-plot method was performed using the analysis software included with the nitrogen adsorption device (product name: BELMaster, manufactured by Microtrac-Bel) under the following conditions. Nitrogen gas adsorption was performed using the standard constant-volume method. Adsorbate cross-sectional area: 0.162 nm 2 Saturated water vapor pressure: 103.72 kPa First straight line: A straight line connecting the point at t=0nm and the point at t=0.27±0.03nm. Second line: A line connecting the points at t=0.80±0.10nm and t=1.00±0.10nm. (HC pass rate before and after hydrothermal treatment) <Preparation of measurement samples> The sample to be measured was subjected to a pressure of 400 kgf / cm². 2 The material was then molded into a cylindrical shape with a diameter of 20 mm and a height of 10 mm under pressure conditions for 60 seconds. Next, it was crushed using a mortar and pestle and classified to obtain irregularly shaped pellet-like molded bodies with an aggregation diameter of 20 to 30 mesh. The obtained molded bodies were used as measurement samples for the example and comparative example, respectively.

[0099] <Hydrothermal treatment> 3 mL (bulk volume) of the obtained molded body was filled into an atmospheric pressure fixed bed flow-through reaction tube, and hydrothermal treatment was performed under the following conditions to obtain a molded body after hydrothermal treatment.

[0100] Treatment gas: 10 vol% water Dry air for the remainder Gas flow rate: 200 mL / min Space velocity: 4000 hr -1 Treatment temperature: 900 °C Treatment time: 1 hour <Pretreatment of measurement sample> 0.1 g of the molded body obtained in the preparation of the measurement sample and 0.1 g of the molded body after hydrothermal treatment were each filled into an atmospheric pressure fixed bed flow-through reaction tube, treated at 500 °C for 30 minutes under nitrogen flow, and then cooled to 50 °C as a pretreatment.

[0101] <HC passing rate> Hydrocarbon-containing gas was passed through each of the measurement samples subjected to the above pretreatment, and the hydrocarbons passed through the sample between 50 °C and 600 °C were measured. The composition of the hydrocarbon-containing gas and the measurement conditions are shown below.

[0102] Hydrocarbon-containing gas: Toluene 3000 volume ppmC (methane conversion concentration) Water 3 vol% Nitrogen for the remainder Gas flow rate: 200 mL / min Measurement temperature: 50 - 600 °C Heating rate: 10 °C / min Measurement time: 55 minutes The inlet concentration and the outlet concentration were measured using an FID. The integrated value of the inlet concentration was taken as the HC amount before flow [μmolC], and the integrated value of the outlet concentration was taken as the HC amount after flow [μmolC]. The hydrocarbon passing rate (hereinafter also referred to as "HC passing rate") was calculated using the following formula from the HC amount before flow and the HC amount after flow in the range of the measurement temperature from 50 °C to 200 °C.

[0103] HC passing rate [%] =100-((HC amount before distribution - HC amount after distribution) / HC amount before distribution)×100 Example 1 50 g of FAU-type zeolite (product name: HSZ(registered trademark)-341NHA, manufactured by Tosoh Corporation; bulk SAR: 7.3, Na2O: 0.08 mass%, water content: 16.0 mass%, lattice constant: 24.531 Å, cation type: ammonium ion and sodium type, Al ratio in the skeleton: 77.1%) was heated to 700°C at a heating rate of 3.7°C / min in an atmosphere through which a water vapor mixed gas with a water content of 5 volume% was circulated, followed by calcination at 700°C for 2 hours, and then allowed to cool to room temperature over 6 hours to obtain a calcined zeolite body. The calcined zeolite body had a water content of 10.3 mass%, a lattice constant of 24.418 Å, a bulk SAR of 7.3, an Al ratio in the skeleton of 44.3%, a Na2O content of 0.08 mass%, and a cation type of hydrogen ion and sodium ion type.

[0104] Next, 35.7 g of the calcined zeolite body was mixed with 102 g of pure water and stirred to obtain a zeolite slurry. Then, 12.8 g of 35% by mass hydrochloric acid was added so that the HCl / zeolite mass ratio was 0.14, and the mixture was stirred at 60°C for 1 hour to obtain a zeolite slurry with a solid content of 20.0% by mass. The obtained zeolite slurry was filtered, washed with pure water, and then dried in air at 110°C for 15 hours to obtain a zeolite acid-treated body. The zeolite acid-treated body had a water content of 8.0% by mass, a lattice constant of 24.452 Å, a bulk SAR of 12.7, an Al ratio in the skeleton of 93.4%, a Na2O content of 0.03% by mass, and a cation type of hydrogen ion and sodium ion type.

[0105] Next, 10.9 g of the zeolite acid-treated material was mixed with 3.9 g of pure water and 1.95 g of a 38.8% by mass copper nitrate aqueous solution, and dried in air at 110°C for 15 hours. The dried sample was calcined in air at 550°C for 2 hours to obtain the copper-containing FAU type zeolite of this example. The obtained zeolite of this example had a lattice constant of 24.422 Å, a bulk SAR of 12.7, an Al ratio in the skeleton of 79.0%, a Na2O content of 0.03% by mass, a copper content of 2.5% by mass, a cation type of copper ion, hydrogen ion, and sodium ion type, an average crystal diameter of 0.75 μm, and a BET specific surface area of ​​845 m². 2 The concentration was 0.33 mL / g, and the micropore volume was 0.33 mL / g.

[0106] Comparative Example 1 304 g of FAU-type zeolite (product name: HSZ(registered trademark)-341NHA, manufactured by Tosoh Corporation; bulk SAR: 7.3, Na2O: 0.08 mass%, water content: 16.0 mass%, lattice constant: 24.531 Å, cation type: ammonium ion and sodium ion type, Al ratio in the skeleton: 77.1%) was mixed with 74.0 g of pure water and 49.7 g of 38.8 mass% copper nitrate aqueous solution, and then dried in air at 110°C for 15 hours. The dried sample was calcined in air at 550°C for 2 hours to obtain copper-containing FAU-type zeolite, which was used as the zeolite for this comparative example. The zeolite obtained in this comparative example had a lattice constant of 24.491 Å, a bulk SAR of 7.3, an Al ratio within the framework of 64.9%, a Na2O content of 0.08 mass%, a copper content of 2.6 mass%, a cation type of copper ions, hydrogen ions, and sodium ions, an average crystal diameter of 0.75 μm, and a BET specific surface area of ​​799 m². 2 The concentration was 0.32 mL / g, and the micropore volume was 0.32 mL / g.

[0107] Comparative Example 2 500g of FAU-type zeolite (product name: HSZ(registered trademark)-341NHA, manufactured by Tosoh Corporation; bulk SAR: 7.3, Na2O: 0.08 mass%, water content: 16.0 mass%, lattice constant: 24.531 Å, cation type: ammonium ion and sodium ion type, Al ratio in the skeleton: 77.1%) was heated to 740°C at a heating rate of 4.0°C / min in an atmosphere through which a water vapor mixed gas with a water content of 30 volume% was circulated, followed by calcination at 740°C for 2 hours, and then allowed to cool for 6 hours to obtain a calcined zeolite body. The calcined zeolite body had a water content of 3.8 mass%, a lattice constant of 24.340 Å, a bulk SAR of 7.3, an Al ratio in the skeleton of 24.4%, a Na2O content of 0.08 mass%, and a cation type of hydrogen ion and sodium ion type.

[0108] Next, 385 g of the calcined zeolite body was mixed with 1280 g of pure water and stirred to obtain a zeolite slurry. Then, 185 g of 35% by mass hydrochloric acid was added so that the HCl / zeolite mass ratio was 0.175, and the mixture was stirred at 60°C for 1 hour to obtain a zeolite slurry with a solid content of 20.0% by mass. The obtained zeolite slurry was filtered, washed with pure water, and then dried in air at 110°C for 15 hours to obtain a zeolite acid-treated body. The zeolite acid-treated body had a water content of 9.6% by mass, a lattice constant of 24.367 Å, ​​a bulk SAR of 23.6, an Al ratio in the skeleton of 100%, a Na2O content of 0.07% by mass, and a cation type of hydrogen ion and sodium ion type.

[0109] Next, 282 g of the zeolite acid-treated material was mixed with 95.5 g of pure water and 49.7 g of a 38.8% by mass copper nitrate aqueous solution, and dried in air at 110°C for 15 hours. The dried sample was calcined in air at 550°C for 2 hours to obtain a copper-containing FAU type zeolite, which was used as the zeolite for this comparative example. The obtained zeolite for this comparative example had a lattice constant of 24.358 Å, a bulk SAR of 14.7, an Al ratio in the skeleton of 58.0%, a Na2O content of 0.07% by mass, a copper content of 2.3% by mass, a cation type of copper ion, hydrogen ion, and sodium ion type, and an average crystal diameter of 0.75 μm.

[0110] Comparative Example 3 A zeolite calcined body was obtained in the same manner as in Example 1, except that air with a moisture content of 0% by volume was used instead of a water vapor mixed gas. The zeolite calcined body had a water content of 6.2% by mass, a lattice constant of 24.443 Å, a bulk SAR of 7.3, an Al ratio in the skeleton of 56.9%, a Na2O content of 0.08% by mass, and a cation type of hydrogen ion and sodium ion type.

[0111] Next, 10.7 g of the calcined zeolite was mixed with 4.1 g of pure water and 1.95 g of a 38.8% by mass copper nitrate aqueous solution, and dried in air at 110°C for 15 hours. The dried sample was calcined in air at 550°C for 2 hours to obtain a copper-containing FAU type zeolite, which was used as the zeolite for this comparative example. The obtained zeolite for this comparative example had a lattice constant of 24.443 Å, a bulk SAR of 14.7, an Al ratio in the skeleton of 51.2%, a Na2O content of 0.08% by mass, a copper content of 2.5% by mass, a cation type of copper ion, hydrogen ion, and sodium ion type, and an average crystal diameter of 0.75 μm.

[0112] Comparative Example 4 A zeolite slurry was obtained by mixing 39.7 g of FAU-type zeolite (product name: HSZ(registered trademark)-331HSA, manufactured by Tosoh Corporation; SiO2 / Al2O3=6.1, Na2O:0.24 mass%, water content: 19.4 mass%, lattice constant: 24.480 Å, Al ratio in the skeleton: 51.6%, cation type: hydrogen ion and sodium ion type) with 97.9 g of pure water and stirring. Next, 6.4 g of 35 mass% hydrochloric acid was added to obtain a zeolite slurry with a solid content of 20.0 mass% so that the HCl / zeolite mass ratio was 0.070, and the slurry was stirred at 60°C for 1 hour. The obtained zeolite slurry was filtered, and 80 g of 20 mass% aqueous ammonium chloride solution was passed through the resulting cake and washed with pure water. After that, it was dried in air at 110°C for 3 hours to obtain a zeolite acid treated body. The zeolite-treated material had a water content of 30.3% by mass, a lattice constant of 24.521 Å, a bulk SAR of 8.6, an Al ratio within the skeleton of 56.9%, a Na2O content of 0.05% by mass, and a cation type consisting of hydrogen ions and sodium ions.

[0113] Next, 14.3 g of the zeolite acid-treated material was mixed with 0.5 g of pure water and 1.95 g of a 38.8% by mass copper nitrate aqueous solution, kneaded by hand in a mortar for 10 minutes, and then dried in air at 110°C for 15 hours. The dried sample was calcined in air at 550°C for 2 hours to obtain a copper-containing FAU type zeolite, which was used as the zeolite for this comparative example. The obtained zeolite for this comparative example had a lattice constant of 24.492 Å, a bulk SAR of 8.6, an Al ratio in the skeleton of 76.9%, a Na2O content of 0.05% by mass, a copper content of 2.5% by mass, a cation type of copper ion, hydrogen ion, and sodium type, and an average crystal diameter of 0.75 μm.

[0114] The HC pass rates of the copper-containing FAU type zeolites in Example 1 and Comparative Examples 1 to 4 before and after hydrothermal treatment are shown in the table below.

[0115] [Table 1]

[0116] From Example 1 and Comparative Examples 1 to 4, it can be confirmed that copper-containing FAU type zeolites included in hydrocarbon adsorbents that have a lattice constant of 24.370 Å or more and 24.490 Å or less, a bulk SAR of 10 or more and 20 or less, and an Al ratio in the skeleton of 70% or more and 100% or less exhibit lower HC pass rates both before and after hydrothermal treatment compared to copper-containing FAU type zeolites that do not meet these conditions.

[0117] From Example 1 and Comparative Examples 1, 2, and 4, it can be confirmed that copper-containing FAU-type zeolites with a lattice constant of less than 24.370 Å or greater than 24.490 Å have lower HC pass rates both before and after hydrothermal treatment compared to copper-containing FAU-type zeolites with a lattice constant of 24.370 Å or more and 24.490 Å or less.

[0118] From Example 1 and Comparative Example 3, it can be confirmed that even if the lattice constant is between 24.370 Å and 24.490 Å, copper-containing FAU-type zeolites with an Al ratio of 70% or more in the skeleton have a lower HC pass rate before hydrothermal treatment compared to copper-containing FAU-type zeolites with an Al ratio of less than 70% in the skeleton. [Industrial applicability]

[0119] The copper-containing FAU-type zeolite of this disclosure can be used in a hydrocarbon adsorption method, and in particular can be used in a method for adsorbing hydrocarbons in exhaust gas from internal combustion engines such as automobile exhaust gas.

Claims

1. A copper-containing FAU-type zeolite having a lattice constant of 24.370 Å or more and 24.490 Å or less, a bulk SAR of 10 or more and 20 or less, and an Al ratio within the framework of 70% or more and 100% or less.

2. The copper-containing FAU type zeolite according to claim 1, wherein the copper content is 0.5% by mass or more and 5.0% by mass or less.

3. The copper-containing FAU type zeolite according to claim 1 or 2, wherein the alkali metal content is 0% by mass or more and 0.15% by mass or less.

4. The copper-containing FAU type zeolite according to claim 1 or 2, wherein the average crystal diameter is 0.5 μm or more and 2.0 μm or less.

5. BET specific surface area is 300 m ２ / g or more 1500m ２ The copper-containing FAU type zeolite according to claim 1 or 2, wherein the amount is less than or equal to / g and the micropore volume is 0.20 mL / g or more and 0.70 mL / g or less.

6. A method for producing copper-containing FAU-type zeolite according to claim 1 or 2, comprising: a firing step of firing a raw material FAU-type zeolite having an alkali metal content of 0% by mass or more and 0.20% by mass or less in an air atmosphere containing 3% by volume or more and 10% by volume or less of water vapor; and an acid treatment step of contacting the zeolite firing body obtained in the firing step with an acid.

7. A method for producing copper-containing FAU-type zeolite according to claim 6, wherein the lattice constant of the raw material FAU-type zeolite is 24.350 Å or more and 24.550 Å or less, the firing temperature in the firing step is 500°C or more and 800°C, and the acid in the acid treatment step is hydrochloric acid.

8. A method for producing copper-containing FAU type zeolite according to claim 7, wherein in the acid treatment step, the zeolite calcined body is brought into contact with hydrochloric acid such that the mass ratio of hydrogen chloride to the zeolite calcined body is 0.035 or more and 0.600 or less.

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