JP2020066564A - Rho type zeolite and manufacturing method therefor - Google Patents

Abstract

To provide novel RHO type zeolite excellent in water heat durability and useful for an absorbent or a catalyst, and a manufacturing method of the RHO type zeolite in which use of crown ether and a cationic polymer as a structure regulation agent is not essential.SOLUTION: There is provided a manufacturing method including crystallization of a composition containing an alumina source, a silica source, a cesium source, a 1,2-dimethyl-3-(4-methylbenzyl)-imidazolium cation source, a halogen source and water. RHO type zeolite has a powder X ray diffraction pattern having following peaks of relative intensity at following lattice spacing d (Å) at least.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to RHO-type zeolite and a method for producing the same.

  The RHO-type zeolite is a small-pore zeolite having an oxygen 8-membered ring, and its application to a catalyst for olefin conversion reaction of methanol (MTO catalyst) and a nitrogen oxide reduction catalyst is being studied (Patent Document 1, Non-Patent Document 1). 1).

  Until now, various production methods have been reported as the production method of RHO-type zeolite. For example, in Patent Document 1, by crystallizing a raw material composed of sodium hydroxide, aluminum hydroxide, cesium hydroxide, precipitated silica and water, and containing no organic structure directing agent, the molar ratio of silica to alumina is 6 It has been reported that RHO-type zeolite of 0.3 can be obtained.

  In Non-Patent Document 1, a RHO-type zeolite having a molar ratio of silica to alumina of 3.9 to 15.9 is obtained by crystallizing and calcining a raw material using a complex of a crown ether and cesium as an organic structure directing agent. It is reported that Further, in Patent Document 2, a synthetic procedure is examined, and after a crown ether-alkali aqueous solution and an aluminum atom raw material solution are mixed, a silicon atom raw material-containing liquid is mixed with this to obtain an aqueous gel, which is crystallized and fired. By doing so, it has been reported that a RHO type zeolite having a silica to alumina molar ratio of 9.9 to 18.8 can be obtained.

  Further, in Non-Patent Document 2, a cationic polymer is used to crystallize and calcine a raw material containing no cesium, and a RHO having a silica to alumina molar ratio of 5.4 (Si / Al = 2.7). It has been reported that type zeolites are obtained.

US Pat. No. 3,904,738 International Publication No. 2015/020014

"Chemical Asian Journal (Chem. Asian J.)", Wiley-VCH Verlag GmbH & Co. (Germany), 2017, VOL 12, 1043-1047. "Microporous and Mesoporous Materials", Elsevier, (Netherlands), VOL 132, 2010, 352-356.

  The present disclosure aims to provide a novel RHO-type zeolite and a method for producing the RHO-type zeolite which does not require the use of a crown ether and a cationic polymer.

  In the present disclosure, RHO type zeolite and a method for producing the same were examined. As a result, they have found that the RHO-type zeolite having characteristics different from those of the conventional RHO-type zeolite and the RHO-type zeolite can be produced from a raw material system different from the conventional production method.

That is, the gist of the present disclosure is as follows.
[1] A RHO-type zeolite characterized by having a powder X-ray diffraction pattern having the following peaks of relative intensity in at least the following lattice spacing d (Å).
[2] The RHO-type zeolite according to the above [1], wherein the molar ratio of silica to alumina is 10 or more.
[3] The RHO-type zeolite according to the above [1] or [2], wherein the average particle size of the primary crystal particles contained in the RHO-type zeolite is 1.5 μm or more.
[4] A crystallization step of crystallizing a composition containing an alumina source, a silica source, a cesium source, a 1,2-dimethyl-3- (4-methylbenzyl) -imidazolium cation source, a halogen source and water. The method for producing an RHO-type zeolite according to any one of the above [1] to [3], characterized in that
[5] A catalyst containing the RHO-type zeolite according to any one of [1] to [4] above.
[6] An adsorbent containing the RHO-type zeolite according to any one of [1] to [4] above.

  According to the present disclosure, it is possible to provide a novel RHO-type zeolite and a method for producing an RHO-type zeolite that does not require the use of a crown ether and a cationic polymer.

SEM observation view of the RHO-type zeolite of Example 1

  Hereinafter, the present disclosure will be described by showing an example of an embodiment.

  This embodiment relates to RHO type zeolite. The RHO-type zeolite has a crystal structure (hereinafter, also simply referred to as “RHO structure”) which becomes an RHO structure with a structure code defined by the International Zeolite Society. The crystal structure of zeolite can be identified by comparing the XRD pattern obtained by powder X-ray diffraction (hereinafter, also referred to as “XRD”) measurement with the XRD pattern of the crystal structure defined by the International Zeolite Society.

In the present embodiment, the XRD pattern can be acquired by XRD measurement performed under the following conditions.
Radiation source: CuKα ray (λ = 1.5405Å)
Measurement mode: Step scan
Scan condition: 32 ° / min
Measurement time: 3 seconds

  Zeolites generally mean porous inorganic oxides or crystalline aluminosilicates. In this embodiment, the zeolite is preferably crystalline aluminosilicate. The crystalline aluminosilicate has a crystal structure in which silicon (Si) and aluminum (Al) have a network structure through oxygen (O). Note that, in the present embodiment, the crystalline aluminosilicate is different from a crystalline silicoaluminophosphate (SAPO) or crystalline aluminophosphate (AlPO) containing phosphorus in the network structure, that is, a zeolite analog.

The RHO-type zeolite of the present embodiment has an XRD pattern having at least the following relative intensity peaks (hereinafter, also simply referred to as “XRD peaks”) at the following lattice spacing d (Å). In other words, the RHO-type zeolite of the present embodiment has an XRD pattern in which at least the lattice spacing d (Å) shown in the table below has a peak top having a peak satisfying the relative intensity in the table below.

Preferably, or more preferably, the RHO-type zeolite in the present embodiment has an XRD pattern in which at least the lattice spacing d (Å) shown in the following table has the peak of the relative intensity shown in the following table.

  In the XRD pattern of the RHO-type zeolite of the present embodiment, in addition to the XRD peaks shown in the above table, peaks having a relative intensity of 20% or more (lattice spacing d (Å) = within the range of 9.96 to 11.25) It is preferable not to include peaks having a relative intensity of 20% or more when the relative intensity of the peak is 100%. On the other hand, in addition to the XRD peaks shown in the above table, peaks having a relative intensity of less than 10% and derived from RHO-type zeolite may be included.

  Preferably, the XRD peak is a peak of the RHO-type zeolite in a state of not containing an organic structure directing agent (hereinafter, also referred to as “SDA”).

The RHO-type zeolite of the present embodiment may contain SDA, but a specific SDA such as 1,2-dimethyl-3- (4-methylbenzyl) -imidazolium (hereinafter, also referred to as “DMMBI”) cation is used. , The relative intensity of the XRD peak (the relative intensity of the XRD peak shown in the table above) changes. For example, the RHO-type zeolite of the present embodiment containing a specific SDA such as DMMBI cation has an XRD pattern in which at least the lattice spacing d (Å) shown in the following table shows the peak of the relative intensity shown in the following table. Have.

Preferably, or more preferably, the RHO-type zeolite of the present embodiment containing a specific SDA such as DMMBI cation has at least a lattice spacing d (Å) shown in the following table and a relative strength shown in the following table. XRD pattern in which the peak of 1 appears.

  In the RHO-type zeolite of the present embodiment, the form containing SDA is not particularly limited, but for example, the form in which SDA is supported in the pores of the oxygen 8-membered ring or the oxygen 8-membered ring is used. An example is a form in which SDA is supported on the outer surface except inside the pores. In addition, when SDA is contained in the RHO-type zeolite of the present embodiment, SDA can be removed by the organic structure directing agent removal treatment described later, and RHO-type zeolite from which SDA has been removed is shown in Table 2 or Table 3 above. It has an XRD pattern in which the XRD peak shown in FIG.

The RHO-type zeolite of the present embodiment has a molar ratio of silica to alumina (hereinafter also referred to as “SiO ₂ / Al ₂ O ₃ ratio”) from the viewpoint of higher heat resistance or solid acidity more suitable for a catalyst carrier. .) Is preferably 10 or more and 50 or less, and more preferably 15 or more and 30 or less.

The RHO-type zeolite of the present embodiment preferably has a cation type of either a proton type (H ⁺ type) or an ammonium type (NH ₄ ⁺ type) (that is, it contains a proton or an ammonium ion as a cation). More preferably, it is more preferably an ammonium type.

  The RHO-type zeolite of the present embodiment includes crystal particles in which individual primary particles independently grow (hereinafter, also referred to as “primary crystal particles”). The primary crystal grains are observed as independent substantially spherical crystal grains in an electron microscope observation.

  Since the RHO-type zeolite of the present embodiment tends to suppress the collapse of crystallinity due to the hydrothermal durability treatment, the average particle size of primary crystal particles (hereinafter, also referred to as “average crystal particle size”) is 1. The thickness is preferably 5 μm or more and 5.0 μm or less, and more preferably 2.0 μm or more and 3.0 μm or less.

  The average crystal grain size can be obtained by measuring the horizontal Feret's diameter of 150 or more primary crystal grains in an electron microscope observation and averaging them. The observation magnification of the electron microscope is preferably 3,000 to 15,000 times.

  The RHO-type zeolite of the present embodiment may contain at least either copper or iron. By containing copper or iron in the RHO-type zeolite of the present embodiment, the reducing characteristics of nitrogen oxides tend to be improved. The form containing copper or iron is not particularly limited, but, for example, a form in which copper or iron is supported in the pores of the oxygen 8-membered ring or the pores of the oxygen 8-membered ring are excluded. An example is a form in which copper or iron is supported on the outer surface. Copper and iron can be contained in the RHO-type zeolite of the present embodiment by at least one method selected from the group consisting of an ion exchange method, an evaporation-drying method and an impregnation-supporting method. Examples of the raw material of copper or iron to be contained in the RHO-type zeolite include at least one selected from the group consisting of inorganic acid salts and further sulfates, nitrates, acetates and chlorides.

  The RHO-type zeolite of this embodiment can be used as an adsorbent, a catalyst, an ion exchanger, and a carrier thereof. More specifically, the RHO-type zeolite of the present embodiment can be used as a nitrogen oxide reduction catalyst, and the nitrogen oxide is reduced by bringing the RHO-type zeolite of the present embodiment into contact with the nitrogen oxide. It

  Next, a method for producing the RHO-type zeolite of this embodiment will be described.

  The RHO-type zeolite of the present embodiment is a composition containing an alumina source, a silica source, a cesium source, a 1,2-dimethyl-3- (4-methylbenzyl) -imidazolium cation source, a halogen source and water (hereinafter, referred to as " Also referred to as a "raw material composition").

The alumina source is alumina (Al ₂ O ₃ ) or an aluminum compound as a precursor thereof, and examples thereof include alumina, aluminum sulfate, aluminum nitrate, sodium aluminate, aluminum hydroxide, aluminum chloride, amorphous aluminosilicate, and metal. At least one selected from the group of aluminum and aluminum alkoxide can be mentioned, and it is preferably at least one selected from the group of sodium aluminate, amorphous aluminosilicate and aluminum alkoxide.

The silica source is silica (SiO ₂ ) or a silicon compound which is a precursor thereof, and includes, for example, colloidal silica, amorphous silica, sodium silicate, tetraethyl orthosilicate, precipitated silica, fumed silica and amorphous aluminosilicate. At least one selected from the group can be mentioned, and at least one selected from the group of tetraethyl orthosilicate, colloidal silica, precipitated silica and amorphous aluminosilicate is preferable.

  The amorphous aluminosilicate is a compound (hereinafter, also referred to as “silica-alumina source”) that functions as both an alumina source and a silica source contained in the raw material composition.

  The cesium source is a salt containing cesium, and is preferably at least one selected from the group consisting of cesium hydroxide, fluoride, chloride, bromide and iodide. More preferably, cesium hydroxide or cesium fluoride is used.

  The raw material composition may contain a salt containing at least one selected from the group consisting of lithium, sodium, potassium and rubidium (hereinafter, also referred to as “alkali source”). The alkali source is preferably at least one selected from the group of hydroxide, fluoride, chloride, bromide and iodide, and more preferably hydroxide or fluoride. At least one of sodium hydroxide and potassium hydroxide is mentioned as a particularly preferable alkali source. When a fluoride is used as the alkali source, the fluoride also functions as a halogen source contained in the raw material composition.

  1,2-Dimethyl-3- (4-methylbenzyl) -imidazolium cation source is a salt of DMMBI, hydroxide, chloride, bromide, iodide, monoester carbonate, monosulfate salt of DMMBI , At least one selected from the group of nitrates and sulfates, and more preferably at least one selected from the group of DMMBI hydroxides, chlorides and bromides.

The DMMBI cation is a quaternary ammonium cation represented by the following general formula, and functions as an organic structure directing agent (SDA) that directs an RHO structure.

  The halogen source is a halide, preferably bromide or fluoride, more preferably fluoride. Examples of particularly preferable halides include hydrogen fluoride (HF), quaternary ammonium fluoride, and alkali metal fluoride. When an alkali metal halide is used as the halogen source, the alkali metal halide also functions as an alkali source that can be contained in the raw material composition.

  Examples of water contained in the raw material composition include deionized water and pure water. At least one of the raw materials (alumina source, silica source, cesium source, 1,2-dimethyl-3- (4-methylbenzyl) -imidazolium cation source, halogen source) contained in the raw material composition is In the case of a hydrate, a hydrate, or an aqueous hydrate, the water contained therein can function as the water contained in the raw material composition.

  Examples of the composition of the raw material composition include the following compositions.

SiO ₂ / Al ₂ O ₃ ratio: 5 or more and 500 or less,
Preferably 10 or more and 100 or less,
More preferably 15 or more and 50 or less

DMMBI / SiO ₂ ratio: 0.03 or more and 1.00 or less,
Preferably 0.10 or more and 0.80 or less,
More preferably 0.30 or more and 0.60 or less

Cs / SiO ₂ ratio: 0.01 or more and 1.00 or less
Preferably 0.05 or more and 0.80 or less,
More preferably 0.06 or more and 0.50 or less

M / SiO ₂ ratio: 0 or more and 0.50 or less
Preferably 0 or more and 0.10 or less,
More preferably 0 or more and 0.05 or less

X / SiO ₂ ratio: 0.30 or more and 2.0 or less
Preferably 0.4 or more and 1.5 or less,
More preferably 0.5 or more and 1.0 or less

H ₂ O / SiO ₂ ratio: 2 or more and 10 or less
Preferably 3 or more and 8 or less,
More preferably 4 or more and 6 or less

In the above composition, the SiO ₂ / Al ₂ O ₃ ratio is the molar ratio of silica to alumina, the DMMBI / SiO ₂ ratio is the molar ratio of DMMBI cation to silica, and the Cs / SiO ₂ ratio is the molar ratio of cesium to silica, M / The SiO ₂ ratio is the molar ratio of alkali metal to silica, the X / SiO ₂ ratio is the molar ratio of halogen to silica, and the H ₂ O / SiO ₂ ratio is the molar ratio of water to silica (H ₂ O).

M in the M / SiO ₂ ratio is at least one alkali metal selected from the group of lithium, sodium, potassium and rubidium, and when the alkali metal (M) is sodium (Na), the M / SiO ₂ ratio is Na. / SiO ₂ ratio. Similarly, when the halogen (X) is fluorine (F), the X / SiO ₂ ratio becomes the F / SiO ₂ ratio.

The raw material composition may include seed crystals, and the seed crystals are preferably RHO-type zeolite. The content of seed crystals relative to the raw material composition (hereinafter, also referred to as “seed crystal content”) was calculated by converting silicon (Si) contained in the raw material composition (raw material composition excluding the seed crystals) into SiO ₂ . The ratio of the weight of silicon contained in the seed crystal as SiO ₂ to the weight is preferably 0% by weight or more and 20% by weight or less, more preferably 5% by weight or more and 10% by weight or less.

  By hydrothermally treating the raw material composition, the raw material composition is crystallized and RHO-type zeolite is obtained. Examples of the hydrothermal treatment include filling the raw material composition in a closed container, sealing this, and then heating. The hydrothermal treatment may be performed either in a state where the raw material composition is allowed to stand or a state where it is stirred, and it is preferable to perform it in a state where it is stirred.

  The crystallization temperature is preferably 100 ° C or higher and 200 ° C or lower, more preferably 120 ° C or higher and 190 ° C or lower, and further preferably 150 ° C or higher and 180 ° C or lower.

  The crystallization time changes from the crystallization temperature, and the crystallization time tends to become shorter as the crystallization temperature increases. For example, the crystallization time is 10 hours or more and 240 hours or less, preferably 24 hours or more and 120 hours or less.

  The manufacturing method according to the present embodiment may include at least one of a cleaning step, an ion exchange step, a drying step, and an organic structure directing agent removing step.

  The washing step reduces impurities from the RHO-type zeolite. Although the washing method is arbitrary, for example, a method of recovering the RHO-type zeolite by solid-liquid separation, mixing it with a sufficient amount of pure water, and washing it can be mentioned.

In the ion exchange step, the RHO-type zeolite is made into any cation type, for example, ammonium type (NH ₄ ⁺ type) or proton type (H ⁺ type) (that is, as the cation of the produced RHO type zeolite, proton or ammonium). Contain ions). Ion exchange method is arbitrary, and for example, a method of the NH ₄ ⁺ type cation type by mixing and stirring the RHO-type zeolite in an aqueous solution of ammonium chloride, by the cationic type firing the NH ₄ ⁺ type RHO type zeolite And a method of setting the cation type to H ⁺ type.

  The drying step removes water from the RHO-type zeolite. The drying method is arbitrary, but for example, RHO-type zeolite may be allowed to stand in the air at 50 ° C. or higher and 150 ° C. or lower for 2 hours or more.

  The organic structure directing agent removing step removes the DMMBI cation contained in the RHO-type zeolite. The method of removing the DMMBI cations is arbitrary, but examples thereof include treatment (for example, firing treatment) at 400 ° C. or higher and 800 ° C. or lower in the air. By performing the organic structure directing agent removing process in the organic structure directing agent removing step, the RHO-type zeolite of the present embodiment containing no SDA can be produced. On the other hand, if the organic structure directing agent is not removed, the RHO-type zeolite of the present embodiment containing SDA can be produced.

  Hereinafter, the present disclosure will be specifically described based on Examples and Comparative Examples. However, the present disclosure is not limited to the following examples.

(Crystal identification)
A powder X-ray diffractometer (device name: Ultima IV, manufactured by Rigaku Corporation) was used to measure the XRD of the sample. The measurement conditions were as follows.
Radiation source: CuKα ray (λ = 1.5405Å)
Measurement mode: Step scan
Scan condition: 32 ° / min
Measurement time: 3 seconds
Measuring range: 2θ = 5 ° to 31 °

(Composition analysis)
A sample solution was prepared by dissolving the sample in a mixed aqueous solution of hydrofluoric acid and nitric acid. The sample solution was measured by inductively coupled plasma optical emission spectroscopy (ICP-AES) using an ICP device (device name: OPTIMA5300DV, manufactured by PerkinElmer).

(Hydrothermal endurance treatment)
The sample was press-molded to obtain agglomerated particles having an agglomerate diameter capable of passing through a 12 to 20 mesh net. At a temperature of 900 ° C., 3 mL of the agglomerated particle sample was filled in an atmospheric pressure fixed bed flow type reaction tube, and air having a water concentration of 10% by volume was flowed through this at 300 mL / min (6,000 h ⁻¹ as space velocity). By performing the treatment for 4 hours, the hydrothermal durability treatment was performed.

(Evaluation of crystallinity and heat resistance)
The samples after the hydrothermal durability treatment were subjected to XRD measurement in the same manner as in the above-described crystal identification to obtain XRD patterns. The crystallinity was defined as the intensity of the XRD peak at the lattice spacing d (Å) = 3.45 to 3.59 in the obtained XRD pattern.

Using the value of the crystallinity of the sample after the hydrothermal durability treatment, the change in the crystallinity before and after the hydrothermal treatment was obtained from the following formula and used as an index of heat resistance.
Change in crystallinity (%) = P2 / P1 x 100
P1 is the crystallinity before the hydrothermal durability treatment, and P2 is the crystallinity after the hydrothermal durability treatment.

Synthesis Example 1 (Synthesis of RHO-type zeolite for seed crystals)
RHO-type zeolite was manufactured by a method according to “Microporous Materials”, Elsevier, (Netherlands), VOL 4, 1995, pp. 231-238 (hereinafter also referred to as “references”). . That is, 18-crown-6-ether (hereinafter also referred to as "crown ether"), pure water, sodium hydroxide, cesium hydroxide and sodium aluminate are mixed to obtain a composition, which is heated to 80 ° C. did.

After heating, the temperature was lowered to room temperature, silica sol was mixed with the composition, and the mixture was stirred at room temperature for 24 hours to obtain a raw material composition having the following molar composition.
SiO ₂ / _Al 2 _{O 3} ratio = 10
Crown ether / SiO ₂ ratio = 0.05
Cs / SiO ₂ ratio = 0.06
Na / SiO ₂ ratio = 0.36
H ₂ O / SiO ₂ ratio = 10

  The raw material composition was filled in a closed container, and the raw material composition was crystallized at 120 ° C. for 4 days. The obtained crystallized product was subjected to solid-liquid separation, washed with ethanol and warm pure water, and then dried at 80 ° C. in the atmosphere.

The crystallized product was a single-phase RHO-type zeolite, which was used as the RHO-type zeolite of this synthesis example. The main XRD peaks of the RHO-type zeolite (peaks having a relative intensity of 10% or more when the relative intensity of the peak with a lattice spacing d (Å) = 10.64 is 100%) are shown in the table below.

The RHO-type zeolite was calcined in the air at 600 ° C. for 2 hours to remove the crown ether. The SiO ₂ / Al ₂ O ₃ ratio of the RHO-type zeolite after removal of the crown ether was 9.5, and the average particle size of the primary crystal particles was 1.10 μm. The main XRD peaks of RHO-type zeolite after removal of crown ether (peaks with a relative intensity of 10% or more when the relative intensity of the peak at lattice spacing d (Å) = 10.59 is 100%) are shown in the table below. Show.

Example 1
Aluminum isopropoxide was mixed with a 22.3 wt% DMMBI hydroxide aqueous solution, and the mixture was stirred at 80 ° C. until the aluminum isopropoxide was dissolved. After stirring, cesium fluoride and tetraethyl orthosilicate were mixed with the aqueous solution, and this was stirred at 50 ° C. After stirring the aqueous solution overnight, hydrogen fluoride was mixed with this to obtain a raw material composition having the following molar composition.
SiO ₂ / Al ₂ O ₃ ratio = 30
DMMBI / SiO ₂ ratio = 0.5
Cs / SiO ₂ ratio = 0.2
F / SiO ₂ ratio = 0.69
H ₂ O / SiO ₂ ratio = 4

Further, seed crystals content (raw material composition (with respect to the weight of silicon (Si) contained in the raw material composition) excluding the seed crystals was calculated as SiO _2, silicon contained in the seed of the weight calculated as SiO ₂ (Ratio) is 10 wt%, the RHO-type zeolite obtained in Synthesis Example 1 was added to and mixed with the composition, the raw material composition was filled in a closed container, and the container was rotated at 20 rpm, This was crystallized by treating at 175 ° C. for 4 days. The obtained crystallized product was subjected to solid-liquid separation, washed with ethanol and warm pure water, and then dried at 110 ° C. in the atmosphere.

The crystallized product was a single phase RHO type zeolite. Main XRD peak of RHO-type zeolite (RHO-type zeolite in the state of including SDA) (relative intensity of 10% or more when relative intensity of the peak of lattice spacing d (Å) = 10.57 is 100%) ) Is shown in the table below.

  As can be understood from the above table, the RHO-type zeolite of this example obtained by crystallizing the raw material composition contained all the XRD peaks shown in Table 4.

The RHO-type zeolite obtained by crystallizing the raw material composition was calcined in the air at 600 ° C. for 2 hours to remove DMMBI. The RHO-type zeolite after firing (the RHO-type zeolite without SDA) had a SiO ₂ / Al ₂ O ₃ ratio of 27.3 and an average particle size of 2.03 μm. The main XRD peaks of the RHO-type zeolite after calcination (peaks having a relative intensity of 10% or more when the relative intensity of the peak at the lattice spacing d (Å) = 10.54 is 100%) are shown in the table below. Further, FIG. 1 shows a view (photograph) of the RHO-type zeolite after firing observed with a scanning electron microscope (SEM). The scale of FIG. 1 shows 5 μm.

  As can be seen from the above table, the RHO-type zeolite after calcination contained all the XRD peaks shown in Table 2.

Comparative Example 1
The crown ether was removed by baking at 600 ° C. for 2 hours obtained in Synthesis Example 1. The RHO-type zeolite after removal of the crown ether was used as the RHO-type zeolite of this comparative example.

  As can be understood from the comparison between Tables 2 and 7, the RHO-type zeolite of this comparative example has XRD peaks of lattice spacing d = 6.12Å, 4.74Å, 3.54Å, 3.35Å, and 2.94Å. The relative intensity was different from the relative intensity of the XRD peak of the RHO-type zeolite of this embodiment. In particular, unlike the RHO zeolite of this example, the RHO zeolite of this comparative example has an XRD peak with a relative intensity of 10% or more in the range of lattice spacing d of 7.16 to 7.80 (Å). I didn't.

  From this, it was found that the RHO-type zeolite of the present embodiment is a novel RHO-type zeolite having a different crystal structure from the conventional RHO-type zeolite.

Example 2
The RHO-type zeolite after firing obtained in Example 1 and a 20% ammonium chloride aqueous solution were mixed and stirred. Then, filtration and washing were performed, and these were dried in air at 110 ° C. overnight to obtain an RHO-type zeolite whose cation type was NH ₄ ⁺ type.

After subjecting the obtained RHO-type zeolite to hydrothermal durability treatment, heat resistance was evaluated. The results are shown in the table below.

From the above table, it can be seen that the RHO-type zeolite of this example maintains high crystallinity even after exposure to a high temperature and high humidity atmosphere, that is, the RHO-type zeolite of this example has high heat resistance.

Claims (6)

An RHO-type zeolite characterized by having a powder X-ray diffraction pattern having the following peaks of relative intensity in at least the following lattice spacing d (Å).
  The RHO-type zeolite according to claim 1, wherein the molar ratio of silica to alumina is 10 or more.   The RHO-type zeolite according to claim 1 or 2, wherein the primary crystal particles contained in the RHO-type zeolite have an average particle size of 1.5 µm or more.   A crystallizing step for crystallizing a composition comprising an alumina source, a silica source, a cesium source, a 1,2-dimethyl-3- (4-methylbenzyl) -imidazolium cation source, a halogen source and water. The method for producing the RHO-type zeolite according to any one of claims 1 to 3.   A catalyst comprising the RHO-type zeolite according to any one of claims 1 to 4. An adsorbent containing the RHO-type zeolite according to any one of claims 1 to 4.