JP7602938B2 - Hydrocarbon adsorbent for exhaust gas, its manufacturing method, and HC trap for exhaust gas purification - Google Patents

Description

The present invention relates to a hydrocarbon adsorbent for exhaust gas, a method for producing the same, and an HC trap for exhaust gas purification.

Exhaust gas from internal combustion engines of automobiles and other vehicles contains hydrocarbons (HC), nitrogen oxides (NOx), carbon monoxide (CO), and particulate matter (PM), and these are efficiently purified by exhaust gas purification systems equipped with various exhaust gas purification catalysts developed according to the type of internal combustion engine.

However, for example, many internal combustion engine exhaust gas purification catalysts exhibit sufficient catalytic activity when the catalyst temperature is around 200°C. Therefore, if the exhaust gas purification catalyst has not yet reached a temperature at which it exhibits sufficient catalytic activity, it will not exhibit the expected exhaust gas purification performance. For this reason, it is expected that there may be cases where HC emissions are high, for example, during a cold start, such as immediately after starting the engine.

For this reason, improvements to the purification performance of HC emitted at low temperatures in internal combustion engines are being studied. Specifically, a method is known in which the HC contained in the exhaust gas is temporarily trapped (adsorbed, held) in a hydrocarbon adsorbent until the exhaust gas purification catalyst is warmed up to a temperature at which it exhibits sufficient catalytic activity, and then the HC is gradually desorbed from the hydrocarbon adsorbent as the catalyst temperature rises, and then purified by the exhaust gas purification catalyst, thereby improving the HC purification performance.

As such hydrocarbon adsorbents for exhaust gas, those using various zeolites are known. For example, Patent Document 1 discloses a gas component reduction material in which Ag is supported on β-type zeolite with a silica-alumina ratio (silica-alumina ratio) of 120 or more or 200 or more in order to improve heat resistance.

Patent Document 2 also discloses that a hydrocarbon adsorbent for exhaust gas made of multidimensional pore zeolite (ISV structure zeolite, BEC structure zeolite, MCM-68 (MSE structure zeolite), MWW structure zeolite) having two-dimensional and/or three-dimensional pores composed of 12-membered rings and/or 10-membered rings exhibits a higher HC adsorption rate than β-type zeolite.

Meanwhile, Patent Document 3 discloses a catalyst layer containing a composition in which an active metal selected from potassium, rubidium, cesium, beryllium, magnesium, calcium, barium, or strontium, or a mixture of two or more of these, is impregnated onto a hydrocarbon adsorption material, and specifically, it shows that impregnating ZSM-5 (MFI type zeolite) with cesium improves HC purification performance.

Patent Document 4 also discloses that the HC adsorption and purification performance can be improved by incorporating a special intercalation compound prepared using a host compound and a guest substance into the HC adsorption layer.

JP 2002-001109 A JP 2004-105821 A Special Publication No. 2004-504130 JP 2006-297375 A

However, the above-mentioned conventional hydrocarbon adsorbents for exhaust gas have poor performance in releasing trapped HC, and as a result, their HC purification performance during cold starts remains insufficient.

The present invention has been made in consideration of the above problems, and its purpose is to provide a hydrocarbon adsorbent for exhaust gas, a manufacturing method thereof, and an HC trap for exhaust gas purification, which have a high HC desorption start temperature for adsorbed HC and can exhibit high HC purification performance during cold start.

In addition to the objectives described here, the present invention also aims to achieve effects that cannot be obtained by conventional techniques, which are derived from the various components shown in the detailed description of the invention described below.

As a result of intensive research into solving the above problems, the inventors discovered that K-X-supported MSE-type zeolite, in which a specific element is supported on MSE-type zeolite, has a high HC desorption initiation temperature for adsorbed HC and can exhibit high HC purification performance during cold starts. They also discovered that the above problems can be solved by using this as a hydrocarbon adsorbent for exhaust gas, which led to the completion of the present invention.

That is, the present invention provides various specific embodiments as shown below.
[1] An exhaust gas hydrocarbon adsorbent comprising: an MSE zeolite; and potassium and X (wherein X is one or more elements selected from the group consisting of alkali metals other than K, alkaline earth metals, and transition metals) supported on the MSE zeolite, wherein the MSE zeolite has a silica-alumina ratio ( _SiO2 / _{Al2O3 )} of 10 or more and 100 or less in molar ratio, and X has a potassium ratio (X/K) of 2.0 or more and 25.0 or less in molar ratio.

[2] The hydrocarbon adsorbent for exhaust gas according to [1], in which the potassium to alumina ratio (K/Al) is 0.04 or more and 0.50 or less in molar ratio.

[3] The hydrocarbon adsorbent for exhaust gas according to [1] or [2], in which the alumina ratio of X (X/Al) is 0.10 or more and 1.50 or less in molar ratio.

[4] A hydrocarbon adsorbent for exhaust gas according to any one of [1] to [3], which has a crystallite diameter of 10 nm or more and 100 nm or less in powder X-ray diffraction measurement.

[5] A hydrocarbon adsorbent for exhaust gas according to any one of [1] to [4], having an average particle diameter D50 of 0.01 μm or more and 20 μm or less.

[6] The hydrocarbon adsorbent for exhaust gas according to any one of [1] to [5], wherein X is one or more selected from the group consisting of Cs, Rb, Ba, Sr, Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Mo, Cu, Ag, and Au.

[7] An HC trap for exhaust gas purification used in an exhaust gas purification system that purifies exhaust gas from an internal combustion engine, comprising a honeycomb-type substrate and a hydrocarbon adsorption layer provided on and/or within the honeycomb-type substrate, the hydrocarbon adsorption layer containing at least the exhaust gas hydrocarbon adsorbent described in any one of [1] to [6].

[8] The HC trap for purifying exhaust gas described in [7], in which the hydrocarbon adsorption layer contains 1 g/L or more and 150 g/L or less of the exhaust gas hydrocarbon adsorbent based on the unit volume (1 L) of the honeycomb-type substrate.

[9] The HC trap for purifying exhaust gas according to [7] or [8], wherein the hydrocarbon adsorption layer is a hydrocarbon adsorption catalyst layer containing one or more precious metal components selected from the group consisting of Pt, Pd, and Rh.

[10] An HC trap for purifying exhaust gas according to any one of [7] to [9], further comprising a catalyst layer.

[11] A method for producing a K-X-supported MSE zeolite, comprising at least the steps of preparing a K-supported MSE zeolite, and adding X (wherein X is one or more elements selected from the group consisting of alkali metals other than K, alkaline earth metals, and transition metals) to the K-supported MSE zeolite to synthesize a K-X-supported MSE zeolite.

[12] The method for producing K-X-supported MSE zeolite according to [11], in the step of synthesizing the K-X-supported MSE zeolite, the X is supported on the K-supported MSE zeolite by an ion exchange method.

[13] A method for producing K-X-supported MSE-type zeolite according to [11] or [12], in which the K-supported MSE-type zeolite is synthesized by hydrothermal synthesis in the presence of potassium in the step of preparing the K-supported MSE-type zeolite.

According to the present invention, it is possible to realize an exhaust gas hydrocarbon adsorbent that has a high HC desorption start temperature for adsorbed HC and can exhibit high HC purification performance during cold start, thereby realizing an exhaust gas purification HC trap and an exhaust gas purification HC trap catalyst that have excellent purification performance. Furthermore, according to the present invention, such a high-performance exhaust gas hydrocarbon adsorbent can be supplied by an industrially simple process and at a relatively low cost.

The following describes in detail the embodiments of the present invention. The following embodiments are examples (representative examples) of the present invention, and the present invention is not limited to these. The present invention can be modified as desired without departing from the spirit of the invention. In this specification, when "~" is used to express a numerical value or physical property value between the two, it is used to include the values before and after the two. For example, the expression of a numerical range of "1 to 100" includes both the lower limit "1" and the upper limit "100". The same applies to the expressions of other numerical ranges.

[Hydrocarbon adsorbent for exhaust gas]
The exhaust gas hydrocarbon adsorbent of this embodiment contains at least MSE zeolite, and potassium and X (wherein X is one or more elements selected from the group consisting of alkali metals other than K, alkaline earth metals, and transition metals) supported on the MSE zeolite, and is characterized in that the silica-alumina ratio ( _SiO2 / _Al2O3 ) of the MSE zeolite is, in molar ratio, 10 or more and 100 or less, and the potassium ratio (X/K) of _X is, in molar ratio, 2.0 or more and 25.0 or less.

MSE zeolite is an aluminosilicate that has been given the framework type code MSE by the International Zeolite Association (hereinafter sometimes abbreviated as "IZA"). MSE zeolite has a three-dimensional pore structure unique to MSE, in which large pores (12-membered ring pores) and medium pores (10-membered ring pores) intersect three-dimensionally, and has a relatively large surface area and large internal space, so that its molecular sieve action gives it a high adsorption capacity for hydrocarbons (HCs) such as benzene, toluene, xylene, and benzaldehyde. The structure of this MSE zeolite can be identified by comparing it with either the powder X-ray diffraction (hereinafter referred to as "XRD") pattern described in Collection of simulated XRD powder patterns for zeolites, Fifth revised edition (2007) or the XRD pattern described in Zeolite Framework Types on the IZA Structure Committee's website http://www.iza-struture.org/databases/.

The silica-alumina ratio (SiO ₂ /Al ₂ O ₃ , molar ratio, hereinafter sometimes simply referred to as "SAR") of MSE zeolite can be appropriately set according to the desired performance, and is not particularly limited, but is generally preferably 10 to 100 in molar ratio, more preferably 15 to 80, and even more preferably 18 to 60. In this specification, the silica-alumina ratio means a value obtained from fluorescent X-ray analysis. Specifically, a sample obtained by pressurizing and molding about 5 g of a sample at 20 t using Axios (Spectolysis Co., Ltd.) was subjected to measurement, and the SAR was calculated from the results of the mass % of SiO ₂ and Al ₂ O ₃ obtained. If the silica-alumina ratio is large, the hydrothermal resistance tends to be excellent, and therefore it is expected to be used in applications exposed to high-temperature exhaust gas. On the other hand, if the silica-alumina ratio is small, the hydrophilicity tends to be excellent and the acid amount tends to be high, and therefore it is expected to show high activity as a solid acid catalyst.

The MSE type zeolite used here is not particularly limited, but from the viewpoint of thermal durability and catalytic performance, it is preferable that the crystallite size is 10 nm or more and 100 nm or less, more preferably 15 nm or more and 90 nm or less, and even more preferably 20 nm or more and 80 nm or less, as measured by powder X-ray diffraction.

When used in powder form, the particle size of the MSE zeolite can be set appropriately according to the required performance, etc., and is not particularly limited. From the viewpoint of surface area, handling, etc., the average particle size D50 is preferably 0.01 μm to 20 μm, more preferably 0.1 to 18 μm, and even more preferably 0.5 μm to 15 μm. In this specification, the average particle size D50 means the median diameter measured by a laser diffraction type particle size distribution measuring device (for example, the laser diffraction type particle size distribution measuring device SALD-3100 manufactured by Shimadzu Corporation). The particle shape of the zeolite is not particularly limited, and may be, for example, rectangular, spherical, ellipsoidal, crushed, flat, or irregular.

The BET specific surface area of the MSE zeolite can be appropriately set depending on the required performance, etc., and is not particularly limited, but is preferably 100 ^m2 /g or more and 1000 ^m2 /g or less, more preferably 300 ^m2 /g or more and 800 ^m2 /g or less, and even more preferably 300 ^m2 /g or more and 600 ^m2 /g or less.

MSE type zeolite can be synthesized by methods known in the industry, and the synthesis method is not particularly limited. As a representative synthesis method, for example, a method of hydrothermal synthesis from a mixture (raw material composition) containing a silica source (e.g., colloidal silica, silica gel, sodium silicate, etc.), an alumina source (or a silica-alumina source), an alkali metal source such as an alkali metal hydroxide (e.g., NaOH, KOH, etc.), an organic structure directing agent OSDA (e.g., tetraethylammonium ions such as tetraethylammonium hydroxide, tetraethylammonium bromide, tetraethylammonium chloride, etc.; N,N,N',N'-tetraalkylbicyclo[2,2,2]oct-7-ene-2,3:5,6-dipyrrolidinium dication such as N,N,N',N'-tetraethylbicyclo[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidinium diiodide; 1,1-dimethyl-1-azonia-4-aza-4-cyclohexylcyclohexane; dimethyldipropylammonium, etc.), and water, etc. is known. The treatment temperature (reaction temperature) of the hydrothermal synthesis is not particularly limited, but is usually 100° C. or more and 200° C. or less, preferably 120° C. or more and 190° C. or less, and more preferably 150° C. or more and 180° C. or less, from the viewpoint of the crystallinity and economic efficiency of the obtained MSE zeolite. The treatment time (reaction time) of the hydrothermal synthesis is not particularly limited as long as it is sufficient to crystallize the zeolite over a sufficient period of time, but is usually 1 hour or more and 20 days or less, preferably 4 hours or more and 16 days or less, and more preferably 12 hours or more and 14 days or less, from the viewpoint of the crystallinity and economic efficiency of the obtained MSE zeolite. After the synthesis, the desired MSE zeolite can be obtained by carrying out a solid-liquid separation treatment, a water washing treatment, a drying treatment for removing water in the air at a temperature of about 50 to 150° C., etc., according to a conventional method, as necessary. Alternatively, MSE zeolite can be synthesized without using OSDA by using an already synthesized MSE zeolite as a seed crystal and hydrothermally synthesizing a mixture containing FAU zeolite, which is a silica-alumina source, an alkali metal source such as NaOH or KOH, and water. From the viewpoints of ease of synthesis and economic efficiency, it is preferable to synthesize MSE zeolite by hydrothermal synthesis in the presence of potassium as an alkali metal source.

In addition, the synthesized MSE type zeolite may contain organic structure-directing agents and alkali metals in the pores. Therefore, if necessary, the organic structure-directing agent can be removed by performing a liquid phase treatment using an acidic aqueous solution, a liquid phase treatment using a chemical solution containing a decomposition component of the organic structure-directing agent, an exchange treatment using a resin, or a calcination treatment at 400°C to 800°C, preferably 450°C to 750°C. These treatments can be performed in any combination. Among these, the organic structure-directing agent is preferably removed by calcination treatment from the viewpoint of production efficiency. The treatment time (calcination time) in the calcination treatment can be set appropriately depending on the treatment temperature and economic efficiency, and is not particularly limited, but is usually 0.5 hours to 72 hours, preferably 1 hour to 48 hours, and more preferably 3 hours to 40 hours.

The above-mentioned zeolite may have metal ions such as alkali metal ions on its ion exchange sites. Here, an ion exchange process for performing ion exchange can be performed according to the desired performance. In this ion exchange process, ions can be exchanged into nonmetallic cations such as ammonium ions (NH ₄ ⁺ ) and protons (H ⁺ ) according to a conventional method. For example, MSE zeolite can be ion-exchanged into ammonium type by performing a liquid phase treatment using an aqueous solution containing ammonium ions such as an aqueous ammonium nitrate solution or an aqueous ammonium chloride solution. In addition, MSE zeolite can be ion-exchanged into proton type by performing a calcination treatment after ion exchange with ammonia. In addition, if necessary, an acid amount reduction treatment can be further performed. The acid amount reduction treatment can be performed by, for example, silylation, steam treatment, dicarboxylic acid treatment, or the like.

The hydrocarbon adsorbent for exhaust gas of this embodiment contains at least potassium and X (wherein X is one or more elements selected from the group consisting of alkali metals other than K, alkaline earth metals, and transition metals) supported on MSE zeolite. Here, K and X can exist in the form of oxides or composite oxides, or in the form of ions at the zeolite adsorption site. MSE zeolite supported with potassium and X in this way has a higher HC desorption start temperature of adsorbed HC than those not supported with potassium and X, and can retain HC in the pores until the temperature becomes relatively high, and can suppress HC desorption until just before the temperature (for example, around 200°C) at which sufficient catalytic activity is exhibited, so that higher HC purification performance can be exhibited at cold start.

The potassium supported on the MSE zeolite may be supported on the MSE zeolite by the hydrothermal synthesis described above, or may be added (supported) separately to the MSE zeolite after synthesis. Potassium can be supplied as, for example, sulfate, nitrate, acetate, chloride, oxide, composite oxide, complex salt, or the like. The method for supporting potassium on the MSE zeolite after synthesis may be performed according to a conventional method, and is not particularly limited, but examples include ion exchange, evaporation to dryness, precipitation support, physical mixing, and impregnation support. After the potassium support process, solid-liquid separation, water washing, and drying to remove moisture in air at a temperature of, for example, about 50 to 150°C, may be performed according to conventional methods, as necessary.

The amount of potassium supported can be set appropriately depending on the required performance and is not particularly limited, but the potassium to alumina ratio (K/Al) is preferably 0.04 or more and 0.50 or less in molar ratio, more preferably 0.04 or more and 0.45 or less, and even more preferably 0.05 or more and 0.40 or less.

Examples of X supported on MSE zeolite include, but are not limited to, alkali metals other than K (potassium), such as Li (lithium), Na (sodium), Rb (rubidium), and Cs (cesium); alkaline earth metals such as Be (beryllium), Mg (magnesium), Ca (calcium), Sr (strontium), and Ba (barium); transition elements present between Group 3 and Group 11 in the periodic table, such as Sc (scandium), Ti (titanium), V (vanadium), Cr (chromium), Mn (manganese), Fe (iron), Co (cobalt), Ni (nickel), Cu (copper), Y (yttrium), Zr (zirconium), Nb (niobium), Mo (molybdenum), Tc (technetium), Ru (ruthenium), and Ag (silver). Among X, one or more selected from the group consisting of Cs, Rb, Ba, Sr, Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Mo, Cu, Ag, and Au are preferred, and one or more selected from the group consisting of Cs and Rb are more preferred. By using these preferred elements, the HC desorption start temperature of the adsorbed HC can be increased. X can be supplied, for example, as a sulfate, nitrate, acetate, chloride, oxide, composite oxide, complex salt, or the like. Specific methods for this may be any method in which X is held at least in the ion exchange sites or pores of the MSE zeolite, and include, but are not limited to, ion exchange, evaporation to dryness, precipitation support, physical mixing, and impregnation support. Typically, the MSE zeolite can be ion-exchanged to the X type by performing a liquid phase treatment using an aqueous solution containing X. After the X-supporting treatment, if necessary, solid-liquid separation treatment, water washing treatment, drying treatment to remove moisture at a temperature of about 50 to 150°C in air, etc. can be performed according to conventional methods. In addition, treatment such as reducing the amount of acid can also be performed. The treatment to reduce the amount of acid can be performed, for example, by silylation, steam treatment, dicarboxylic acid treatment, etc. These treatments to reduce the amount of acid and change the composition can be performed according to conventional methods.

The amount of X supported can be set appropriately depending on the required performance and is not particularly limited, but the alumina ratio of X (X/Al) is preferably 0.10 or more and 1.50 or less, more preferably 0.30 or more and 1.25 or less, and even more preferably 0.50 or more and 1.00 or less, in molar ratio.

The potassium ratio of X (X/K) can be set appropriately depending on the required performance and is not particularly limited, but is preferably 2.0 or more and 25.0 or less, more preferably 5.0 or more and 23.0 or less, and even more preferably 7.0 or more and 20.0 or less, in molar ratio.

Here, a preferred method for producing K-X-supported MSE zeolite includes a method in which K-supported MSE zeolite is synthesized by hydrothermal synthesis in the presence of potassium, and X is added to this K-supported MSE zeolite by ion exchange to obtain K-X-supported MSE zeolite. In this way, by using MSE zeolite (Brønsted acid type having protonic hydrogen atoms) on which potassium has already been supported by hydrothermal synthesis, and further adding X by ion exchange to obtain K-X-supported MSE zeolite (Lewis acid type), the process is simplified and adjustment of the potassium to alumina ratio (K/Al), the X to alumina ratio (X/Al), and the X to potassium ratio (X/K), etc. is facilitated. From this viewpoint, it is desirable that a preferred production method does not have a separate step of ion-exchanging MSE zeolite to NH ₄ ⁺ type (for example, a step of subjecting MSE zeolite to liquid-phase treatment using an aqueous solution containing ammonium ions such as an aqueous solution of ammonium nitrate or ammonium chloride).

The K-X-supported MSE-type zeolite of the present invention is a promising solid acid catalyst, and also has relatively excellent heat resistance, making it a promising hydrocarbon adsorbent. More specifically, it is particularly promising as a catalyst for catalytic cracking of paraffin, for example, as a cracking catalyst for long-chain hydrocarbons (e.g., hexane) in the petrochemical industry, and also as an HC trap for purifying exhaust gas from various internal combustion engines such as gasoline engines and diesel engines (e.g., diesel automobiles, gasoline automobiles, jet engines, boilers, gas turbines, etc.).

[HC trap for exhaust gas purification]
The above-mentioned K-X-supported MSE zeolite is particularly effectively used as a hydrocarbon adsorbent for exhaust gas, and can be implemented in various modes. For example, the above-mentioned K-X-supported MSE zeolite can be used as it is in the form of powder. In addition, for example, the powder can be molded into an arbitrary shape to be used as a granular or pellet-shaped molded body. Note that, when preparing the molded body, various known dispersing devices, kneading devices, and molding devices can be used. Furthermore, the above-mentioned K-X-supported MSE zeolite can be supported (supported) on a catalyst carrier such as a ceramic monolith carrier made of cordierite, silicon carbide, silicon nitride, etc., a metal honeycomb carrier or wire mesh carrier made of stainless steel, or a steel wool-like knit wire carrier. Note that these can be used alone or in any combination and ratio of two or more. When the above-mentioned K-X-supported MSE zeolite is supported on a catalyst carrier, various known coating methods, wash coat methods, and zone coat methods can be applied.

In particular, the above-mentioned K-X-supported MSE-type zeolite can be used as an HC trap or HC trap catalyst in various types of exhaust gas purification systems. The embodiment of the HC trap for exhaust gas purification is not particularly limited, but includes an embodiment that includes a honeycomb-type substrate and a hydrocarbon adsorption layer provided on and/or within the honeycomb-type substrate, and the hydrocarbon adsorption layer contains at least the above-mentioned exhaust gas hydrocarbon adsorbent (K-X-supported MSE-type zeolite). By supporting the zeolite on a honeycomb-type substrate in this way, the gas flow rate can be kept relatively high, thereby realizing an efficient HC trap.

The type of honeycomb substrate is not particularly limited as long as it can support the hydrocarbon adsorbent. Examples of the substrate include, but are not limited to, metals, alloys, plastics, ceramics, paper, synthetic paper, nonwoven fabrics, and laminates of combinations of these. The shape, planar shape, thickness, and other properties of the honeycomb substrate may be appropriately set according to the application and required performance. For example, as a support for automobile exhaust gas applications, a ceramic monolith carrier such as cordierite, silicon carbide, or silicon nitride, a metal honeycomb carrier such as stainless steel, a wire mesh honeycomb carrier such as stainless steel, or a steel wool knit wire honeycomb carrier, which are well known in the art, may be used. The outer shape of the substrate may be any shape, such as a prism, a cylinder, a sphere, a honeycomb, or a sheet. These may be used alone or in combination of two or more. By using a honeycomb substrate as a support for the hydrocarbon adsorbent, it becomes easier to install the substrate in a gas flow.

The size of the honeycomb substrate can be appropriately set according to the application and required performance, and is not particularly limited. The number of holes in the openings of the honeycomb substrate may be appropriately set in consideration of the type of exhaust gas to be treated, the gas flow rate, the pressure loss, or the removal efficiency. The cell density is not particularly limited, but from the viewpoint of maintaining a high surface area for the gas flow and suppressing an increase in pressure loss, it is usually preferably 100 to 900 cells/inch ² (15.5 to 139.5 cells/cm ² ), and more preferably 200 to 600 cells/inch ² (31 to 93 cells/cm ² ). The cell density means the number of cells per unit area in the cross section when the honeycomb substrate is cut perpendicularly to the gas flow path.

The honeycomb substrates used for automobile exhaust gases are generally classified into two types: a flow-through structure in which gas flow paths are connected, and a wall-flow structure in which some end faces of the gas flow paths are sealed and gas can flow through the walls of the gas flow paths. While either type can be used in this embodiment, a flow-through structure is preferably used because it has low air resistance and low exhaust gas pressure loss.

The method of applying the above-mentioned K-X-supported MSE-type zeolite to a catalyst carrier or a honeycomb-type substrate may be carried out according to a conventional method and is not particularly limited. For example, the above-mentioned K-X-supported MSE-type zeolite, an aqueous medium, and, if necessary, a binder known in the art, other catalysts, cocatalyst particles, OSC material, base material particles, additives, etc. are mixed in a desired mixing ratio to prepare a slurry (slurry-like mixture), and the obtained slurry-like mixture is applied to a catalyst carrier or a honeycomb-type substrate, and then dried or fired as necessary. At this time, if necessary, an acid or base may be mixed to adjust the pH, or a surfactant or dispersion resin may be mixed to adjust the viscosity or improve the slurry dispersibility. In addition, as a method of mixing the slurry, crushing and mixing using a ball mill or the like can be applied, but other crushing or mixing methods can also be applied. The method of applying the slurry composition to a catalyst carrier or a honeycomb-type substrate may be carried out according to a conventional method and is not particularly limited. Various known coating methods, washcoating methods, and zone coating methods can be applied.

The amount of the slurry composition applied (coating amount) to the catalyst carrier or honeycomb substrate may be appropriately set according to the required performance and is not particularly limited, but from the viewpoint of the balance between NOx adsorption performance or catalytic performance and pressure loss, the amount is preferably 0.1 to 500 g/L, more preferably 10 to 400 g/L, and even more preferably 20 to 300 g/L, calculated based on the composition of the above-mentioned catalyst slurry composition (calculated based on Cu-containing zeolite).

After the application of the slurry composition, the slurry composition can be dried under reduced pressure using a vacuum dryer or the like in the usual manner, and dried at about 50°C to 200°C for about 1 to 48 hours. The slurry composition applied to the catalyst carrier or honeycomb substrate can also be subjected to a firing process, for example, by heat treating the slurry composition at 300°C to 1000°C. The firing temperature can be set appropriately depending on the raw materials used, etc., and is not particularly limited, but is preferably 400°C to 900°C, more preferably 430°C to 800°C, and even more preferably 450°C to 750°C. The treatment time (firing time) in this firing process can be set appropriately depending on the treatment temperature and economic efficiency, and is not particularly limited, but is usually 0.1 hours to 72 hours, preferably 0.2 hours to 48 hours, and more preferably 0.5 hours to 40 hours. The firing process is preferably performed in an oxygen-containing atmosphere, for example, in an air atmosphere. The heating means is not particularly limited, and any known heating means in the industry, such as an electric furnace or gas furnace, can be used.

If necessary, platinum group elements (PGM: Platinum Group Metals) such as platinum, palladium, rhodium, iridium, etc., and transition metals such as Cu, Fe, W, Ce, etc. may be blended in the slurry composition and supported on the surface of the K-X-supported MSE-type zeolite. These can function as catalytically active components for exhaust gas purification, and therefore can impart high catalytic performance to the hydrocarbon adsorption layer (hydrocarbon adsorption catalyst layer). From the viewpoint of catalytic activity, a preferred embodiment is a hydrocarbon adsorption catalyst layer containing one or more selected from the group consisting of Pt, Pd, and Rh. The method of supporting these elements is not particularly limited and may be any known method. For example, a solution of a salt containing a platinum group element or a transition metal element is prepared, the slurry composition (slurry composition for catalyst) is impregnated with this salt-containing solution, and then calcined, thereby supporting the platinum group element or the transition metal element. The platinum group elements and transition metal elements can be supplied, for example, as an aqueous nitrate solution, a dinitrodiammine nitrate solution, an aqueous chloride solution, a sulfate, a nitrate, an acetate, a chloride, an oxide, a composite oxide, a complex salt, and the like, but are not limited to these.

In addition, other zeolites can be used in combination with the above-mentioned K-X-supported MSE-type zeolite. Specific examples of other zeolites include SSF-type zeolite, MFI-type zeolite, MEL-type zeolite, MWW-type zeolite, *BEA-type zeolite, BEC-type zeolite, BIK-type zeolite, BOF-type zeolite, BOG-type zeolite, BRE-type zeolite, CAS-type zeolite, CDO-type zeolite, CFI-type zeolite, -CHI-type zeolite, CON-type zeolite, CSV-type zeolite, DAC-type zeolite, DDR-type zeolite, DOH-type zeolite, DON-type zeolite, EEI-type zeolite, EON-type zeolite, EPI-type zeolite, ESV-type zeolite, EUO-type zeolite, *-EWT-type zeolite, , FER type zeolite, GON type zeolite, HEU type zeolite, IFR type zeolite, -IFU type zeolite, IFW type zeolite, IHW type zeolite, IMF type zeolite, IRN type zeolite, IRR type zeolite, -IRY type zeolite, ISV type zeolite, ITE type zeolite, ITG type zeolite, ITH type zeolite, *-ITN type zeolite, ITR type zeolite, ITT type zeolite, ITW type zeolite, IWR type zeolite, IWS type zeolite, IWV type zeolite, IWW type zeolite, LTF type zeolite, MAZ type zeolite, MEI type zeolite, MEP type zeolite, MF S type zeolite, MON type zeolite, MOR type zeolite, *MRE type zeolite, MTF type zeolite, MTN type zeolite, MTT type zeolite, MTW type zeolite, NES type zeolite, NON type zeolite, NSI type zeolite, OKO type zeolite, -PAR type zeolite, PCR type zeolite, POS type zeolite, RRO type zeolite, RSN type zeolite, RTE type zeolite, RTH type zeolite, RUT type zeolite, RWR type zeolite, SEW type zeolite, SFE type zeolite, SFF type zeolite, SFG type zeolite, SFH type zeolite, SFN type zeolite, SFS type zeolite , *SFV type zeolite, SGT type zeolite, SOF type zeolite, SSF type zeolite, *-SSO type zeolite, SSY type zeolite, STF type zeolite, STI type zeolite, *STO type zeolite, STT type zeolite, STW type zeolite, -SVR type zeolite, SVV type zeolite, SZR type zeolite, TER type zeolite, TON type zeolite, TUN type zeolite, UOS type zeolite, UOV type zeolite, UTL type zeolite, UWY type zeolite, VET type zeolite, VNI type zeolite, VSV type zeolite, YUG type zeolite, etc., but are not particularly limited thereto. Note that these other zeolites can be used alone or in any combination and ratio of two or more.

(binder)
Furthermore, if necessary, a binder may be contained. By blending a binder in the slurry composition, the coating strength of the resulting hydrocarbon adsorption layer (hydrocarbon adsorption layer) and the adhesion to the honeycomb substrate tend to be increased. Here, as the binder, a binder known in the art can be used, and the type is not particularly limited. Examples of the binder include boehmite, colloidal alumina, alumina sol, titania sol, silica sol, zirconia sol, etc., but are not particularly limited thereto. In addition, soluble salts such as aluminum nitrate, aluminum acetate, titanium nitrate, titanium acetate, zirconium nitrate, and zirconium acetate can also be used as binders. In addition, acids such as acetic acid, nitric acid, hydrochloric acid, and sulfuric acid can also be used as binders. The binder can be used alone or in any combination and ratio of two or more types.

The amount of binder used is not particularly limited, and may be any amount necessary to maintain the coating strength and adhesion of the hydrocarbon adsorption layer. Specifically, the binder content is preferably 0.1 to 40 mass % relative to the total amount of the slurry composition, more preferably 1 to 35 mass %, and even more preferably 2 to 30 mass %.

By the above-mentioned manufacturing method, it is possible to obtain a laminated structure HC trap for exhaust gas purification having at least a honeycomb substrate and a hydrocarbon adsorption layer provided on at least one side thereof, and a laminated structure HC trap catalyst for exhaust gas purification having at least a hydrocarbon adsorption catalyst layer provided on at least one side thereof. Here, in this specification, "provided on at least one side of the honeycomb substrate" means that an arbitrary other layer (e.g., a primer layer, an adhesive layer, etc.) is interposed between one side of the honeycomb substrate and the hydrocarbon adsorption layer. In other words, in this specification, "provided on one side" is used to mean both an embodiment in which the honeycomb substrate and the hydrocarbon adsorption layer are directly placed on each other, and an embodiment in which the honeycomb substrate and the hydrocarbon adsorption layer are arranged apart from each other through an arbitrary other layer. In addition, it means that the hydrocarbon adsorption layer may be provided on only one side of the honeycomb substrate, or on multiple sides (e.g., one main surface and the other main surface, etc.). In this case, a honeycomb-type substrate is used, a laminated structure is placed in the flow path through which the gas flow passes, and the gas flow is passed through the cells of the honeycomb-type substrate, allowing for highly efficient exhaust gas purification.

In the laminated HC trap for purifying exhaust gas or the HC trap catalyst for purifying exhaust gas, the hydrocarbon adsorption layer or the hydrocarbon adsorption catalyst layer may be either a single layer or multiple layers. It may be a single layer of only the hydrocarbon adsorption layer, or a single layer of only the hydrocarbon adsorption catalyst layer, or two or more layers of the hydrocarbon adsorption layer may be laminated, or two or more layers of the hydrocarbon adsorption catalyst layer may be combined with the hydrocarbon adsorption layer, or two or more layers of the hydrocarbon adsorption layer may be combined with a catalyst layer known in the industry, or two or more layers of the layer known in the industry and the hydrocarbon adsorption catalyst layer may be combined. In this case, the amount of coating of the above-mentioned hydrocarbon adsorption layer is not particularly limited, but from the viewpoint of the balance between catalyst performance and pressure loss, etc., based on the unit volume (1 L) of the catalyst carrier or honeycomb type substrate or honeycomb type substrate, the amount is preferably 1 g/L or more and 150 g/L in terms of the solid content of the above-mentioned K-X-supported MSE type zeolite, more preferably 3 g/L or more and 135 g/L, and even more preferably 5 g/L or more and 120 g/L.

The above-mentioned HC trap for exhaust gas purification (HC trap catalyst for exhaust gas purification) can be arranged in the exhaust system of various internal combustion engines. The number and locations of the HC traps for exhaust gas purification (HC trap catalyst for exhaust gas purification) can be appropriately designed according to exhaust gas regulations. According to the HC trap for exhaust gas purification (HC trap catalyst for exhaust gas purification) of this embodiment, the HC desorption start temperature of the adsorbed HC is high, and high HC purification performance can be achieved at cold start, thereby realizing an exhaust gas purification system with excellent purification performance. In addition, according to a preferred embodiment of the present invention, such high-performance hydrocarbon adsorbent for exhaust gas, HC trap for exhaust gas purification (HC trap catalyst for exhaust gas purification), and exhaust gas purification system can be supplied by an industrially simple process and at a relatively low cost.

The following test examples, examples, and comparative examples will be used to explain the characteristics of the present invention in more detail, but the present invention is not limited by these in any way. In other words, the materials, amounts used, ratios, processing contents, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. In addition, the various manufacturing conditions and evaluation result values in the following examples are meant as preferred upper or lower limit values in the implementation of the present invention, and the preferred range may be a range defined by a combination of the above-mentioned upper or lower limit values and the values of the following examples or the values of the examples.

(Production Example 1) Synthesis of OSDA First, in accordance with the method described in JP-A-2020-050611, N.N'-diethylbicyclo[2.2.2]oct-7-ene-2,3:5,6-tetracarboxylic dianhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) was synthesized. Next, in accordance with the method described in JP-A-6430303, N,N,N',N'-tetraethylbicyclo[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidinium diiodide was synthesized.

Preparation Example 1 Synthesis of MSE Zeolite Subsequently, MSE zeolite was synthesized according to the method described in T. Shibata et al., Microporous and Mesoporous Materials, 116 (2008) 216. A solution of 102.5 g of colloidal silica (Snowtex N40, Nissan Chemical Industries, Ltd.), 157.0 g of water, 6.0 g of aluminum hydroxide gel (Kyoward KW200S, Kyowa Chemical Industries, Ltd.), and 10 g of potassium hydroxide (FUJIFILM Wako Pure Chemical Industries, Ltd.) dissolved in 90 g of water was mixed with 40.1 g of N,N,N',N'-tetraethylbicyclo[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidinium diiodide of Preparation Example 1, and stirred for 16 hours in a stainless steel beaker. The composition of the mixture was as follows. The numerical values in the following compositions represent the ratio of the amount of substance when the amount of SiO ₂ is taken as 1.
_{SiO2
0.051 Al2O3}
0.100 OSDA
0.375 KOH
30.00 _H2O

Next, this raw material composition (mixture) was divided and placed into two 300cc PTFE pressure-resistant sealed containers and left to stand at 160°C for 384 hours. The product after this hydrothermal treatment was separated into solid and liquid, and the resulting solid phase was washed with water and dried at 105°C to obtain a product. The entire amount of the obtained product was fired at 600°C for 5 hours while circulating air. The product obtained in this manner was subjected to powder fluorescent X-ray analysis (XRD: X-ray diffraction) using a powder fluorescent X-ray analyzer (Bruker Japan Co., Ltd., D8 Advance), and was confirmed to be a single-phase MSE-type zeolite (SAR: 20, crystallite size: 62 nm, average particle size D50: 14 μm). In addition, elemental analysis was performed by ICP method using an ICP emission analyzer (Shimadzu Corporation, ICPS-8100), and the molar ratio was K/Al = 0.35.

Example 1 Cs-K-supported MSE zeolite 5.0 g of the calcined MSE zeolite of Preparation Example 1 was added to an aqueous solution in which 5.0 g of cesium acetate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in 100 g of water, and the mixture was heated and stirred, and held at 80°C for 3 hours. After cooling, the mixture was filtered, and the same operation was repeated once more. The mixture was then washed with water and dried at 105°C for 16 hours to obtain the Cs-K-supported MSE zeolite of Example 1. The obtained Cs-K-supported MSE zeolite of Example 1 was subjected to elemental analysis by the ICP method using an ICP emission spectrometer (Shimadzu Corporation, ICPS-8100, and Thermo Fisher Scientific Co., Ltd. iCAP6500), and the molar ratios were K/Al = 0.06, Cs/Al = 0.76 , and Cs/K = 13.6. The obtained Cs-K supported MSE type zeolite of Example 1 was wet-coated onto a honeycomb type substrate in a coating amount of 100 g per 1 L of the honeycomb type substrate, and then fired at 500°C, thereby obtaining an HC trap for exhaust gas purification of Example 1, in which a hydrocarbon adsorption layer containing the Cs-K supported MSE type zeolite was provided on the honeycomb type substrate.

To evaluate the HC adsorption performance of the Cs-K supported MSE type zeolite of Example 1, toluene adsorption/desorption measurements were carried out. Here, the Cs-K supported MSE type zeolite was separated, and a TPR (Temperature Programmed Reaction) measuring device (MicrotrackBell Corporation BELCAT-A, BEL-Mass) was used to measure the adsorption and desorption of toluene in a Gas-1 (5% Ar, balance He) atmosphere with a saturated vapor pressure setting temperature of 80°C (saturated vapor pressure of 47377 Pa) and a flow rate of 300 cc/min. The gas was heated from 70°C to 600°C at a rate of 30°C/min, then cooled to 600°C to 70°C, and held at 70°C for 10 minutes. Then, the gas was switched to Gas-2 (5% Ar, 2% H ₂ O, 0.007% toluene (500 ppm C toluene), balance He) with a flow rate of 300 cc/min, and the temperature was raised from 70°C to 600°C at a rate of 10°C/min. The toluene desorption temperature was 192°C.

Comparative Example 1 K-H Type MSE Zeolite The calcined MSE zeolite of Preparation Example 1 was used as it was as Comparative Example 1. The K-H type MSE zeolite of Comparative Example 1 was subjected to elemental analysis measurement by the ICP method using an ICP emission spectrometer (Shimadzu Corporation, ICPS-8100), and the molar ratio was K/Al = 0.35. In addition, a toluene adsorption/desorption test was performed in the same manner as in Example 1, and the toluene desorption temperature was 178 ° C.

(Comparative Example 2) K-type MSE zeolite 5.0 g of the calcined MSE zeolite of Preparation Example 1 was added to an aqueous solution in which 2.5 g of potassium acetate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in 100 g of water, and the mixture was heated and stirred, and held at 80 ° C. for 3 hours. After cooling, the mixture was filtered, and the same operation was repeated once more. Then, the mixture was washed with water and dried at 105 ° C. for 16 hours to obtain K-type MSE zeolite of Comparative Example 2. The K-type MSE zeolite of Comparative Example 2 was subjected to elemental analysis measurement by the ICP method using an ICP emission spectrometer (Shimadzu Corporation, ICPS-8100, and Thermo Fisher Scientific Co., Ltd. iCAP6500), and the molar ratio was K/Al = 0.73. In addition, a toluene adsorption/desorption test was performed in the same manner as in Example 1, and the toluene desorption temperature was 168 ° C.

(Comparative Example 3) H ⁺ MSE Zeolite 10.0 g of the calcined MSE zeolite of Preparation Example 1 was added to an aqueous solution in which 15.0 g of ammonium nitrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in 115 g of water, and the mixture was heated and stirred, and held at 80°C for 3 hours. After cooling, the mixture was filtered, and the same operation was repeated once again. The mixture was then washed with water and dried at 105°C for 16 hours to obtain NH ₄ ⁺ MSE zeolite. The obtained NH ₄ ⁺ MSE zeolite was calcined at 500°C for 5 hours to obtain the H ⁺ MSE zeolite of Comparative Example 3. The H ⁺ MSE zeolite of Comparative Example 3 was subjected to elemental analysis by the ICP method using an ICP emission spectrometer (Shimadzu Corporation, ICPS-8100), and the molar ratio was K/Al = 0.07. Furthermore, when a toluene adsorption/desorption test was carried out in the same manner as in Example 1, the toluene desorption temperature was 141°C.

(Comparative Example 4) Cs-K supported MSE type zeolite
5.0 g of the H ⁺ type MSE zeolite of Comparative Example 3 was added to an aqueous solution in which 5.0 g of cesium acetate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in 100 g of water, and the mixture was heated and stirred, and held at 80 ° C. for 3 hours. After cooling, the mixture was filtered, and the same operation was repeated once more. Then, the mixture was washed with water and dried at 105 ° C. for 16 hours to obtain the Cs-K-supported MSE zeolite of Comparative Example 4. The Cs-K-supported MSE zeolite of Comparative Example 4 was subjected to elemental analysis measurement by the ICP method using an ICP emission spectrometer (Shimadzu Corporation, ICPS-8100, and Thermo Fisher Scientific Co., Ltd. iCAP6500), and the molar ratios were K/Al = 0.03, Cs/Al = 0.75 , and Cs/K = 26.5. In addition, a toluene adsorption/desorption test was performed in the same manner as in Example 1, and the toluene desorption temperature was 180 ° C.

(Comparative Example 5) Cs-type FAU-type zeolite 400 g of FAU-type zeolite (HSZ-350HUA, SAR: 11, manufactured by Tosoh Corporation) was added to an aqueous solution in which 147 g of 60 wt % nitric acid (manufactured by Kanto Chemical Co., Ltd.) was dissolved in 4000 g of water, and the solution was heated and stirred, and held at 80 ° C. for 3 hours. After cooling, the solution was filtered, washed with water, and then dried at 105 ° C. to obtain FAU-type zeolite (SAR: 19). 20.0 g of the obtained FAU-type zeolite was added to an aqueous solution in which 20.0 g of cesium acetate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in 550 g of water, and the solution was heated and stirred, and held at 80 ° C. for 3 hours. After cooling, the solution was filtered, and the same operation was repeated once more. After that, the solution was washed with water and dried at 105 ° C. for 16 hours to obtain the Cs-type FAU-type zeolite of Comparative Example 5. Furthermore, when a toluene adsorption/desorption test was carried out in the same manner as in Example 1, the toluene desorption temperature was 161°C.

(Comparative Example 6) Cs-type MFI zeolite MFI zeolite was synthesized with reference to High-Al ZSM-5 described in IZA SYNTHESIS COMMISSION, and ion exchange to Cs type was carried out as follows. 1.5 g of 40 mass% tetrapropylammonium hydroxide solution (manufactured by Seikemui Co., Ltd.), 7.2 g of 4.8 mass% sodium hydroxide solution, and 12.8 g of water were mixed and stirred in a SUS beaker. 3.8 g of amorphous silica Nipsil ER (manufactured by Tosoh Silica Co., Ltd.) was added little by little to this. After stirring for 1 hour, the resulting mixture was placed in a 100 cc PTFE pressure vessel and held at 100 ° C. for 16 hours, and 25.3 g of seeding gel was obtained. 9.1 g of the obtained seeding gel was added with 1.3 g of aluminum hydroxide gel (Kyoward KW200S, manufactured by Kyowa Chemical Industry Co., Ltd.), 73.1 g of 4.8 mass% sodium hydroxide, 87.7 g of water, and 19.2 g of amorphous silica (Nipsil ER, manufactured by Tosoh Corporation) and stirred for 1 hour. The composition of the mixture was as follows. The numerical values in the following compositions represent the ratio of the amount of material when the amount of material of _SiO2 is set to 1.
_{SiO2
0.025 Al2O3}
0.017 OSDA
0.145 _Na2O
29.66 _H2O

Next, this raw material composition (mixture) was divided and charged into two 300cc PTFE pressure-resistant sealed containers, and left to stand at 175°C for 48 hours. The product after this hydrothermal treatment was separated into solid and liquid, and the obtained solid phase was washed with water and dried at 105°C to obtain a product. The entire amount of the obtained product was calcined at 600°C for 5 hours while circulating air. When the product obtained in this way was subjected to powder fluorescent X-ray analysis (XRD: X-ray diffraction) using a powder fluorescent X-ray analyzer (Bruker Japan Co., Ltd., D8 Advance), it was confirmed that it was a single-phase MFI type zeolite (SAR: 40). 10.0 g of the obtained calcined MFI type zeolite was added to an aqueous solution in which 15.0 g of ammonium nitrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in 115 g of water, and the mixture was heated and stirred, and held at 80°C for 3 hours. After cooling, it was filtered, and then the same operation was repeated once again. After that, it was washed with water and dried at 105°C for 16 hours to obtain NH ₄ ⁺ type MFI type zeolite. This was calcined at 500°C for 5 hours to obtain H ⁺ type MFI type zeolite. 5.0 g of the obtained H ⁺ type MFI type zeolite was added to an aqueous solution in which 5.0 g of cesium acetate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in 100 g of water, heated and stirred, and held at 80°C for 3 hours. After cooling, it was filtered, and then the same operation was repeated once again, washed with water, and dried at 105°C for 16 hours to obtain Cs type MFI type zeolite of Comparative Example 6. In addition, when a toluene adsorption/desorption test was performed in the same manner as in Example 1, the toluene desorption temperature was 172°C.

(Comparative Example 7) Cs-type MFI zeolite The amount of seeding gel was 8.7 g, the amount of aluminum hydroxide gel (Kyoward KW200S, manufactured by Kyowa Chemical Co., Ltd.) was 2.6 g, the amount of 4.8 wt% sodium hydroxide was 71.1 g, the amount of water was 84.9 g, and the amount of amorphous silica (Nipsil ER, manufactured by Tosoh Corporation) was 18.7 g. Except for changing the composition of the mixture as follows, MFI zeolite (SAR: 20) was synthesized in the same manner as in Comparative Example 6. The composition of the mixture was as follows. The numerical values in the following compositions represent the substance amount ratio when the substance amount of SiO ₂ is 1.
_{SiO2
0.050 Al2O3}
0.017 OSDA
0.145 _Na2O
29.66 _H2O
The results of XRD showed that a small amount of MOR was by-produced. Thereafter, heat treatment, firing treatment, and ion exchange treatment were performed in the same manner as in Comparative Example 6 to obtain a Cs-type MFI zeolite of Comparative Example 7. In addition, a toluene adsorption/desorption test was performed in the same manner as in Example 1, and the toluene desorption temperature was 172°C.

The evaluation results are shown in Table 1.

The K-X-supported MSE-type zeolite of the present invention can be widely and effectively used as a solid acid catalyst for catalytic cracking of paraffin, a hydrocarbon adsorbent for hydrocarbons (HC) or a hydrocarbon adsorption catalyst, and can be particularly effectively used in HC traps for exhaust gas purification or HC trap catalysts for exhaust gas purification and exhaust gas purification systems for various internal combustion engines such as gasoline engines and diesel engines.

Claims (12)

The present invention comprises at least an MSE zeolite, potassium supported on the MSE zeolite, and X (wherein X is Cs ),
The silica-alumina ratio (SiO ₂ /Al ₂ O ₃ ) of the MSE zeolite is, in terms of molar ratio, 10 or more and 100 or less,
The potassium ratio of X (X/K) is 2.0 or more and 25.0 or less in molar ratio;
Hydrocarbon adsorbent for exhaust gas. 2. The adsorbent for exhaust gases for hydrocarbons according to claim 1, wherein the potassium to alumina ratio (K/Al) is 0.04 or more and 0.50 or less in terms of molar ratio. 3. The adsorbent for exhaust gases for hydrocarbons according to claim 1, wherein the alumina ratio (X/Al) of X is 0.10 or more and 1.50 or less in terms of molar ratio. The adsorbent for exhaust gas hydrocarbons according to any one of claims 1 to 3, which has a crystallite size of 10 nm or more and 100 nm or less in powder X-ray diffraction measurement. The adsorbent for exhaust gas hydrocarbons according to any one of claims 1 to 4, having an average particle size D50 of 0.01 µm or more and 20 µm or less. An HC trap for exhaust gas purification used in an exhaust gas purification system for purifying exhaust gas from an internal combustion engine,
A honeycomb-type substrate and a hydrocarbon adsorption layer provided on and/or within the honeycomb-type substrate,
The hydrocarbon adsorption layer contains at least the exhaust gas hydrocarbon adsorbent according to any one of claims 1 to 5 .
HC trap for exhaust gas purification. The hydrocarbon adsorption layer contains the exhaust gas hydrocarbon adsorbent in an amount of 1 g/L or more and 150 g/L or less based on a unit volume (1 L) of the honeycomb substrate.
7. The HC trap for purifying exhaust gas according to claim 6 . The hydrocarbon adsorption layer is a hydrocarbon adsorption catalyst layer containing one or more precious metal components selected from the group consisting of Pt, Pd, and Rh.
8. An HC trap for purifying exhaust gas according to claim 6 or 7 . Further comprising a catalyst layer
The HC trap for purifying exhaust gas according to any one of claims 6 to 8 . The method includes at least a step of preparing a K-supported MSE zeolite, and a step of adding X (wherein X is Cs ) to the K-supported MSE zeolite to synthesize a K-X-supported MSE zeolite having a silica-alumina ratio (SiO2 _/ Al2O3 _{) of} 10 or more and 100 or less in molar ratio and a potassium ratio (X/K) of X of 2.0 or more and 25.0 or less in molar ratio .
A method for producing KX-supported MSE type zeolite. In the step of synthesizing the K-X-supported MSE zeolite, the K-supported MSE zeolite is supported by an ion exchange method.
The method for producing the K-X-supported MSE zeolite according to claim 10 . In the step of preparing the K-supported MSE zeolite, the K-supported MSE zeolite is synthesized by a hydrothermal synthesis method in the presence of potassium.
The method for producing the KX-supported MSE zeolite according to claim 10 or 11 .