JP7046641B2 - Small pore zeolite containing phosphorus and having an intergrowth structure and its production method - Google Patents

Description

The present invention relates to a small pore zeolite having an intergrowth structure and a method for producing the same. More specifically, the present invention relates to a small pore zeolite containing phosphorus and having an intergrowth structure, which is suitable for a catalyst or a catalyst base material, and a method for producing the same.

Small pore zeolites such as chabazite-type zeolite (hereinafter, also referred to as "CHA-type zeolite") reduce nitrogen oxides (NOx) in exhaust gas discharged from the internal combustion engine of mobile bodies such as automobiles and ships. It is used as a selective catalytic reduction catalyst (hereinafter, also referred to as “SCR catalyst”) for the purpose (Patent Document 1).

In recent years, as a small pore zeolite alternative to CHA-type zeolite, crystalline aluminosilicate having a crystal structure of an AFX structure and an intergrowth of CHA structure has been reported (Patent Document 2).

International Publication No. 2008/106519 Pamphlet JP-A-2017-065943

An object of the present invention is to provide a small pore zeolite having a continuous crystal structure exhibiting higher heat resistance than the small pore zeolite having a continuous crystal structure reported so far. Furthermore, another object of the present invention is to provide an industrial method for producing such a small pore zeolite.

The present inventors have studied small pore zeolites suitable as catalysts or catalyst carriers. As a result, they have found that phosphorus can be contained in a zeolite having an intergrowth structure and that such a zeolite exhibits high heat resistance, and have completed the present invention.

That is, the gist of the present invention is as follows.
[1] A small pore zeolite having a crystal structure of an intergrowth structure of an AFX structure and a CHA structure and containing phosphorus.
[2] The small pore zeolite according to the above [1], which contains the phosphorus in the pores.
[3] The small pore zeolite according to the above [1] or [2], wherein the molar ratio of phosphorus to aluminum is 0.50 or less.
[4] The description according to any one of the above [1] to [3], wherein the ratio of the AFX structure to the total of the CHA structure and the AFX structure in the crystal structure is 0.5 or more and less than 1.0. Small pore zeolite.
[5] The small pore zeolite according to any one of the above [1] to [4], wherein the molar ratio of silica to alumina is 5 or more and 30 or less.
[6] The small pore zeolite according to any one of the above [1] to [5], wherein the molar ratio of phosphorus to the metal atom constituting the skeleton is 0.0005 or more and 0.1 or less. ..
[7] The method for producing a small pore zeolite according to any one of the above [1] to [6], which comprises a silica alumina source, a phosphorus source, an organic structure directing agent source, an alkali source, and water. A method for producing small pore zeolite, which comprises a crystallization step of crystallizing an object.
[8] The small detail according to the above [7], wherein the phosphorus source is at least one selected from the group of tetraethylphosphonium hydroxide, tetraethylphosphonium bromide, tetraethylphosphonium chloride and tetraethylphosphonium iodide. Method for producing pore zeolite.
[9] The method for producing a small pore zeolite according to the above [7] or [8], wherein the silica-alumina source is crystalline aluminosilicate.
[10] The method for producing a small pore zeolite according to any one of the above [7] to [9], wherein the silica alumina source is a FAU type zeolite.
[11] The small pore zeolite according to any one of the above [7] to [10], wherein the organic structure directing agent source is a salt containing a cation that directs each of the CHA structure and the AFX structure. Manufacturing method.
[12] The method for producing a small pore zeolite according to any one of the above [7] to [11], wherein the composition contains a silica source.

INDUSTRIAL APPLICABILITY According to the present invention, a small pore zeolite having a continuous crystal structure exhibiting higher heat resistance than the small pore zeolite having a continuous crystal structure (phosphorus-free small pore zeolite) reported so far can be obtained. Can be provided. Furthermore, the present invention can provide an industrial method for producing such small pore zeolites.

It is an XRD pattern of the small pore zeolite of Example 2. It is a scanning electron microscope observation figure of the small pore zeolite of Example 2. FIG.

Hereinafter, the small pore zeolite of the present invention will be described in detail.

The present invention relates to a small pore zeolite (hereinafter, also referred to as "small pore zeolite of the present invention") characterized in that the crystal structure is an intergrowth structure of an AFX structure and a CHA structure and contains phosphorus. Related.

The small pore zeolite of the present invention is a zeolite whose maximum pores in its crystal structure are pores formed by an oxygen 8-membered ring (hereinafter, also referred to as “oxygen 8-membered ring pore”). Examples of the crystal structure of zeolite whose maximum pores are oxygen 8-membered ring pores include CHA structure, AEI structure, AFX structure, GME structure, LEV structure, KFI structure and SAV structure.

The crystal structure of zeolite is a structural code defined by the International Zeolite Society (hereinafter, also simply referred to as “structural code”), which is described in Collection of simulated XRD powder patterns for zeolites, Fifth revised edition (2007). Powder X-ray diffraction (hereinafter, also referred to as “XRD”) pattern, and the homepage of the IZA Structural Committee http: // www. iza-structure. It can be identified by comparison with any of the XRD patterns described in Zeolite Framework Types of org / database /.

The small pore zeolite of the present invention is preferably crystalline aluminosilicate. In crystalline aluminosilicate, the metal atoms (hereinafter, also referred to as "T atoms") constituting the skeleton are aluminum (Al) and silicon (Si), and these T atoms are formed from a network via oxygen (O). It has a crystal structure consisting of a three-dimensional skeletal structure. The small pore zeolite of the present invention preferably does not contain a zeolite having a metal element other than aluminum and silicon as a T atom, and has an aluminophosphate or silicoaluminophosphate having a skeletal structure consisting of a network containing phosphorus (P). It is more preferable that it does not contain zeolite-related substances such as.

The crystal structure of the small pore zeolite of the present invention is an intergrowth structure of an AFX structure and a CHA structure. An intergrowth is a crystal structure having at least one of a two-dimensional or one-dimensional periodic structure. The crystal structure represented by each structure code, such as the CHA structure, is a crystal structure showing a three-dimensional periodic structure. On the other hand, in the intergrowth structure of the AFX structure and the CHA structure, either the AFX structure or the CHA structure has a three-dimensional periodic structure in the a-axis direction and the b-axis direction, and c. In the axial direction, the AFX structure and the CHA structure are alternately laminated to form a crystal structure having a two-dimensional periodic structure. That is, the intergrowth structure of the AFX structure and the CHA structure is a crystal structure having an irregular stacking of the AFX structure and the CHA structure in addition to the AFX structure and the CHA structure.

The XRD pattern shown by the crystal structure consisting of an intergrowth structure of AFX structure and CHA structure is a zeolite having a CHA structure (hereinafter, also referred to as “CHA type zeolite”) and a zeolite having an AFX structure (hereinafter, “AFX”). It is different from the XRD pattern shown by the mixed zeolite obtained by physically mixing (also referred to as “type zeolite”). That is, the mixed zeolite has an XRD pattern including all XRD peaks corresponding to each of the CHA structure and the AFX structure. On the other hand, the XRD pattern shown by the crystal structure consisting of the intergrowth structure of the AFX structure and the CHA structure is an intergrowth such as an XRD peak in which a part of the XRD peak of the CHA structure or the AFX structure is peak-shifted or a broadened peak. The XRD pattern including the XRD peak derived from the structure is shown.

In the present invention, the intergrowth structure is a powder X-ray diffraction pattern of the intergrowth structure obtained by simulation using DIFFaX (hereinafter, also referred to as “DIFFaX pattern”) and powder X-ray diffraction of the small pore zeolite of the present invention. (Hereinafter, also referred to as "XRD") It can be confirmed by at least one of a method of comparison with a pattern or observation with a transmission electron microscope.

In the small pore zeolite of the present invention, the ratio of the AFX structure to the total of the CHA structure and the AFX structure in the crystal structure (hereinafter, also referred to as “AFX ratio”) is 0.5 or more and less than 1.0, and further 0. It is preferably 6 or more and less than 1.0. The AFX ratio compares the DIFFaX pattern having a crystal structure having a different ratio of CHA structure and AFX structure (hereinafter, also referred to as “linkage ratio”) with the XRD pattern of the small pore zeolite of the present invention. It can be obtained by doing. Specifically, the zeolite ratio in the case of "CHA structure: AFX structure" is 0.1: 0.9, 0.2: 0.8, 0.3: 0.7, 0.4: DIFFaX pattern with a crystal structure of 0.6, 0.5: 0.5, 0.6: 0.4, 0.7: 0.3, 0.8: 0.2, 0.9: 0.1 The AFX ratio is obtained from the intergrowth ratio of the DIFFaX pattern that matches the XRD pattern of the small pore zeolite of the present invention by comparing these DIFFaX patterns with the XRD pattern of the small pore zeolite of the present invention. Can be done.

The small pore zeolite of the present invention contains phosphorus. This makes it possible to improve the heat resistance of the small pore zeolite. Further, by modifying the acid point of the small pore zeolite with phosphorus, various catalysts for producing lower olefins from alcohols and ketones, cracking catalysts, dewax catalysts, isomerization catalysts, nitrogen oxide reduction catalysts and the like are used. It is a small pore zeolite having acid strength suitable as a catalyst for the above and as a base material for various catalysts.

It is preferable that phosphorus is contained in a substance other than the skeleton of the small pore zeolite, that is, it is contained as a substance other than the T atom. The small pore zeolite of the present invention contains phosphorus without a chemical bond between phosphorus and a T atom, so that the thermal stability of aluminum, which is a T atom, is improved. Phosphorus is preferably contained in the pores of the small pore zeolite, more preferably contained in the pores of the crystal structure, and more preferably contained in the oxygen 8-membered ring pores. More preferred. Since phosphorus is present in the pores and further in the oxygen 8-membered ring pores, phosphorus is present in the vicinity of aluminum, which is a T atom. This tends to improve the thermal stability of the aluminum.

The phosphorus content is preferably at least one of a phosphate ion or a phosphorus compound, more preferably a phosphorus compound, and particularly preferably an organic phosphorus compound.

In the small pore zeolite of the present invention, the phosphorus content can be confirmed by NMR measurement.

In the small pore zeolite of the present invention, the molar ratio of phosphorus to T atom (hereinafter, also referred to as “P / T ratio”) is preferably 0.1 or less, and more preferably 0.05 or less. .. When the P / T ratio is 0.1 or less, the pores of the small pore zeolite can sufficiently contribute to the desired reaction such as a catalytic reaction. The P / T ratio is preferably 0.0005 or more, and more preferably 0.001 or more. As a particularly preferable range of P / T ratio, 0.001 or more and 0.1 or less can be mentioned.

In the small pore zeolite of the present invention, the molar ratio of phosphorus to aluminum (hereinafter, also referred to as “P / Al ratio”) is preferably 0.50 or less. When the P / Al ratio is 0.50 or less, the small pore zeolite of the present invention has sufficient acidity and heat resistance for catalytic use. The P / Al ratio is preferably 0.002 or more, more preferably 0.01 or more. The P / Al ratio is particularly preferably 0.002 or more and 0.50 or less in order to facilitate improvement of catalytic activity and heat resistance.

In the small pore zeolite of the present invention, the molar ratio of silica to alumina (hereinafter, also referred to as “SiO ₂ / Al ₂ O ₃ ratio”) is preferably 5 or more and 30 or less, and preferably 5 or more and 25 or less. Is more preferable. When the SiO ₂ / Al ₂ O ₃ ratio is 5 or more, the small pore zeolite of the present invention exhibits sufficient heat resistance in applications such as catalysts. On the other hand, when the SiO ₂ / Al ₂ O ₃ ratio is 30 or less, the small pore zeolite of the present invention has a sufficient amount of acid points as a catalyst. In order to have heat resistance and a sufficient amount of acid points, it is particularly preferable that the SiO ₂ / Al ₂ O ₃ ratio is 5 or more and 20 or less.

It is preferable that the small pore zeolite of the present invention does not substantially contain fluorine (F), that is, the fluorine content is 0 ppm. Generally, the fluorine contained in zeolite is derived from a raw material. Zeolites obtained by using a compound containing fluorine as a raw material tend to have a high production cost. Considering the measurement limit of the measured value obtained by a usual composition analysis method such as lanthanum-alizarin complexone absorptiometry, the fluorine content of the small pore zeolite of the present invention may be 0 ppm or more and 100 ppm or less, and may be 0 ppm or more. It is more preferably 50 ppm or less.

Each composition such as the P / T ratio, the P / Al ratio _, and the SiO ₂ / Al ₂ O3 ratio in the present invention can be measured by a general composition analysis method, for example, the ICP method.

The small pore zeolite of the present invention preferably has a BET specific surface area of 500 m ² / g or more and 1000 m ² / g or less, and more preferably a BET specific surface area of 600 m ² / g or more and 800 m ² / g or less.

The small pore zeolite of the present invention preferably has a pore volume (hereinafter, also referred to as “micropore”) obtained by the t-prot method of 0.2 mL / g or more and 0.4 mL / g or less, and is 0. It is more preferably .25 mL / g or more and 0.35 mL / g or less.

Next, the method for producing the small pore zeolite of the present invention will be described.

The small pore zeolite of the present invention is obtained by a production method comprising a step of crystallizing a composition containing a silica alumina source, a phosphorus source, an organic structure directing agent source, an alkali source and water.

A step of crystallizing a composition containing a silica-alumina source, a phosphorus source, an organic structure-directing agent source, an alkali source and water (hereinafter, also referred to as "raw material composition") (hereinafter, also referred to as "crystallization step"). As a result, the small pore zeolite of the present invention is crystallized from the raw material composition.

The silica-alumina source contained in the raw material composition is a compound containing silicon (Si) and aluminum (Al). When one compound contains silicon and aluminum, the crystallization of the small pore zeolite tends to proceed more efficiently than when the compound contains silicon and aluminum, respectively. Preferred silica-alumina sources include at least one of amorphous aluminosilicates and crystalline aluminosilicates, preferably crystalline aluminosilicates, more preferably FAU-type zeolites, and X-type zeolites or Y. It is more preferably at least one of the type zeolites, and particularly preferably a Y-type zeolite.

In the silica-alumina source, the SiO ₂ / Al ₂ O ₃ ratio is preferably 1.25 or more, and more preferably 5 or more. On the other hand, the SiO ₂ / Al ₂ O ₃ ratio may be 100 or less, preferably 50 or less, and more preferably 10 or less. The SiO ₂ / Al ₂ O ₃ ratio of the preferred silica-alumina source is 1.25 or more and 50 or less, and more preferably 5 or more and 10 or less.

The cation type of the silica-alumina source is arbitrary. Examples of the cation type include at least one selected from the group of sodium type (Na type), proton type (H ⁺ type) and ammonium type ₍ NH4 type), and the sodium type is more preferable.

From the viewpoint of promoting the crystallization of small pore zeolite, it is preferable that the silica source and the alumina source are only the silica alumina source, but in finely adjusting the SiO ₂ / Al ₂ O ₃ ratio of the raw material composition, the silica source is used. Alternatively, it may contain at least one of the alumina sources, preferably a silica source.

The silica source is a compound containing silicon, and examples thereof include at least one selected from the group of silica sol, fumed silica, colloidal silica, precipitated silica, and amorphous silicic acid, and amorphous silicic acid is preferable.

The alumina source is a compound containing aluminum, and examples thereof include at least one selected from the group of aluminum hydroxide, aluminum oxide, aluminum sulfate, aluminum chloride, aluminum nitrate, metallic aluminum, pseudo-bemite, alumina sol, and aluminum alkoxide.

The phosphorus source is a compound of a cation containing phosphorus, preferably a compound containing a phosphonium cation, and is at least one selected from the group of sulfates, nitrates, halides and hydroxides of phosphonium cations. Is more preferable. Phosphorus uptake in the process of crystallization of the raw material composition is affected by charge balance. Therefore, phosphorus-containing cations are incorporated into the crystallized product such as the pores of the crystallized product. In contrast, phosphorus-containing anions are not incorporated into the crystallized product. Therefore, phosphorus ^- containing anions such as phosphoric acid (PO _4-2 ) and its salts do not function as a source of phosphorus.

Preferred phosphorus sources include compounds containing at least one of a tetraethylphosphonium (hereinafter also referred to as “TEP”) cation or a tetramethylphosphonium (hereinafter also referred to as “TMP”) cation, and are compounds containing a TEP cation. It is preferable to have. Preferred phosphorus sources include tetraethylphosphonium hydroxide (hereinafter, also referred to as "TEPOH"), tetraethylphosphonium bromide (hereinafter, also referred to as "TEPBr"), tetraethylphosphonium chloride (hereinafter, also referred to as "TEPCl"), and. , At least one selected from the group of tetraethylphosphonium iodide (hereinafter, also referred to as "TEPI"), and more preferably at least one of TEPOH or TEPBr.

The source of the organic structure-directing agent (hereinafter, also referred to as “SDA”) is a salt containing a cation that directs the CHA structure and the AFX structure, a salt containing a cation that directs the CHA structure, and a cation that directs the AFX structure. Salts may be used, and for example, a salt containing a quaternary ammonium cation that directs the CHA structure and a salt containing a quaternary ammonium cation that directs the AFX structure are preferable. The cations contained in the SDA source crystallize the small pore zeolite, whose crystal structure is an intergrowth structure of CHA structure and AFX structure, from the raw material composition.

The salt containing a cation (hereinafter, also referred to as “SDA _CHA ”) that directs the CHA structure is preferably at least one selected from the group of sulfates, nitrates, halides and hydroxides of SDA _CHA . More preferably, it is at least one of a halide or hydroxide of SDA _CHA .

The SDA _CHA is preferably at least one selected from the group of trimethyl-1-adamantanammonium cations, choline cations and trimethylbenzylammonium cations, and is preferably a trimethyl-1-adamantaneammonium (hereinafter, also referred to as "TMAda") cation. Is more preferable.

The salt containing the TMAda cation includes trimethyl-1-adamantanane ammonium hydroxide (hereinafter, also referred to as “TMadaOH”), trimethyl-1-adamantanammonium bromide (hereinafter, also referred to as “TMadaBr”), and trimethyl-1-adamantan. It is preferably at least one selected from the group of ammonium chloride (hereinafter, also referred to as “TMAdaCl”) and trimethyl-1-adamantane ammonium iodide (hereinafter, also referred to as “TMAdaI”), preferably TMAdaOH or TMAdaBr. It is more preferable that it is at least one of.

The salt containing a cation (hereinafter, also referred to as “SDA _AFX ”) that directs the AFX structure is preferably at least one selected from the group of sulfates, nitrates, halides and hydroxides of SDA _AFX . More preferably, it is at least one of a halide or hydroxide of SDA _AFX .

SDA _CHA is 1,4-bis (1-azabicyclo [2.2.2] octane) butyl cation, 1,4-bis (azoniabicyclo [2.2.2] octane) butyl cation, 1,3-bis ( At least selected from the group of 1-adamantyl) imidazolium cations and N, N, N', N'-tetraethylbicyclo [2.2.2] octene-2, 3: 5,6-dipyrrolidinium cations. One can be mentioned, and 1,4-bis (1-azabicyclo [2.2.2] octane) butyl (hereinafter, also referred to as “Dab-4”) cation is preferable.

Salts containing the Dab-4 cation include 1,4-bis (1-azabicyclo [2.2.2] octane) butyldioxide and 1,4-bis (1-azabicyclo [2.2.2] octane) butyl. From the group dichloride, 1,4-bis (1-azabicyclo [2.2.2] octane) butyldibromid, and 1,4-bis (1-azabicyclo [2.2.2] octane) butyldiiodide. It is preferably at least one selected, and is also referred to as 1,4-bis (1-azabicyclo [2.2.2] octane) butyl dibromid (hereinafter, also referred to as "[Dab-4] ²⁺ (Br- ⁾ ₂ "). .) Is more preferable.

The alkali source is a compound of an alkali metal, preferably an alkali metal hydroxide, more preferably a hydroxide containing at least one selected from the group of lithium, sodium, potassium, rubidium and cesium. It is more preferably a hydroxide containing at least one of sodium and potassium, and particularly preferably a hydroxide containing sodium.

The water may be pure water, but may be structural water derived from each raw material contained in the raw material composition or water as a solvent.

In the raw material composition, the SiO ₂ / Al ₂ O ₃ ratio is preferably 10 or more, and more preferably 20 or more. On the other hand, the SiO ₂ / Al ₂ O ₃ ratio may be 100 or less, preferably 50 or less, and more preferably 40 or less. The preferred SiO ₂ / Al ₂ O ₃ ratio is 10 or more and 50 or less, and more preferably 20 or more and 40 or less.

In the raw material composition, the molar ratio of phosphorus to silica (hereinafter, also referred to as “P / SiO ₂ ratio”) may be 0.001 or more and 1.0 or less, and 0.002 or more and 0.5 or less. Is preferable. In the small pore zeolite, the P / SiO ₂ ratio is preferably 0.01 or more, more preferably 0.1 or more, and 0.1 or more 0. It is more preferably 4 or less.

In the raw material composition, the molar ratio of SDA to silica (hereinafter, also referred to as “SDA / SiO ₂ ratio”) is preferably 0.01 or more, more preferably 0.05 or more, and 0. It is more preferably 10 or more. From the viewpoint of reducing the manufacturing cost, the SDA / SiO ₂ ratio may be 0.50 or less, preferably 0.30 or less, and more preferably 0.20 or less.

When the SDA source is a salt containing SDA _CHA and a salt containing SDA _AFX , the molar ratio of SDA _AFX to the total of SDA _CHA and SDA _AFX (hereinafter, also referred to as “SDA ratio”) is larger than 0. It may be less than 1.

In the raw material composition, the molar ratio of alkali metal to silica (hereinafter, also referred to as “alkali / SiO ₂ ratio”) is preferably 0.1 or more and 1.5 or less, and 0.5 or more and 1.0 or less. Is more preferable.

In the raw material composition, the molar ratio of OH to silica (hereinafter, also referred to as “OH / SiO ₂ ratio”) is preferably 0.1 or more and 1.0 or less, and 0.5 or more and 1.0 or less. It is more preferable to have.

In the raw material composition, the molar ratio of water (H ₂ O) to silica (hereinafter, also referred to as “H ₂ O / SiO ₂ ratio”) is preferably 3 or more and 50 or less, preferably 10 or more and 40 or less. Is more preferable. From the viewpoint of imparting appropriate fluidity to the raw material composition, the H ₂ O / SiO ₂ ratio is preferably 20 or more and 35 or less.

The following ranges can be mentioned as the molar ratio of each preferable raw material composition.
SiO ₂ / Al ₂ O ₃ ratio: 10 or more and 50 or less P / SiO ₂ ratio: 0.001 or more and 1.0 or less SDA / SiO ₂ ratio: 0.01 or more and 0.50 or less (SDA ratio): Greater than 0 Less than 1 Alkaline / SiO ₂ ratio: 0.1 or more and 1.5 or less OH / SiO ₂ ratio: 0.1 or more and 1.0 or less H ₂ O / SiO ₂ ratio: 3 or more and 50 or less

If the raw material composition contains a compound containing fluorine, the production cost tends to be high. Therefore, it is preferable that the raw material composition does not substantially contain fluorine (F). Considering the measurement limit of the measured value obtained by a usual composition analysis method such as lanthanum-alizarin complexone absorptiometry, the fluorine content of the raw material composition may be 0 ppm or more and 100 ppm or less, and is 0 ppm or more and 50 ppm or less. Is more preferable.

In the crystallization step, the raw material composition may be crystallized by hydrothermal treatment.

The temperature of the hydrothermal treatment may be any temperature as long as the crystallization of the raw material composition proceeds, and is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, still more preferably 120 ° C. or higher. Once the raw material composition is crystallized, it is not necessary to raise the temperature of the hydrothermal treatment more than necessary. Therefore, the temperature of the hydrothermal treatment may be 200 ° C. or lower, preferably 180 ° C. or lower, and more preferably 160 ° C. or lower.

In the hydrothermal treatment, the raw material composition may be in either a stirred state or a stationary state.

The production method of the present invention may include at least one of a cleaning step, a drying step and an ion exchange step (hereinafter, also referred to as “post-treatment step”) after the crystallization step.

In the washing step, the small pore zeolite after the crystallization step and the liquid phase may be solid-liquid separated by a known method, and the small pore zeolite obtained as a solid phase may be washed with pure water.

In the drying step, water is removed from the small pore zeolite after the crystallization step or the washing step. The conditions of the drying step are arbitrary, but it can be exemplified that the small pore zeolite after the crystallization step or the washing step is allowed to stand in the air at 50 ° C. or higher and 150 ° C. or lower for 2 hours or longer.

In the ion exchange step, the small pore zeolite is an arbitrary cation type. When the cation type is ammonium type, mixing of small pore zeolite and ammonium chloride aqueous solution can be mentioned. When the cation type is a proton type, calcining an ammonium type small pore zeolite can be mentioned.

Hereinafter, the present invention will be described with reference to examples. However, the present invention is not limited to these examples.

(Identification of crystal structure)
A general X-ray diffractometer (device name: D8 Advance, manufactured by Bruker) was used, and the XRD measurement of the sample was performed under the following conditions.
Radioactive source: CuKα ray (λ = 1.5405Å)
Measurement range: 2θ = 5 ° to 50 °

The crystal structure of the sample was identified by comparing the obtained XRD pattern with the DIFFaX pattern. As the DIFFaX pattern, a DIFFaX pattern having an intergrowth structure of CHA structure and AFX structure having an AFX ratio of 0.7 (CHA structure: AFX structure = 0.3: 0.7) was used.

(Composition analysis)
A sample solution was prepared by dissolving the sample in an aqueous potassium hydroxide solution. The composition of the sample was analyzed by measuring the sample solution by inductively coupled plasma emission spectroscopy (ICP-AES) using a general ICP device (device name: SPS7000, manufactured by Seiko).
From the obtained measured values, each composition of the sample was determined.

(Nitrogen adsorption measurement)
The amount of nitrogen gas adsorbed on the sample was measured using a general nitrogen adsorption device (device name: BELSORP-mini, manufactured by Microtrac Bell Co., Ltd.). The BET specific surface area of the sample was determined by applying the BET method to the adsorption result of nitrogen gas. In addition, the micropore volume was determined by applying the t-prot method to the adsorption result of nitrogen gas. For nitrogen gas adsorption, a normal constant volume method was used. The measurement conditions are as shown below.
Measurement temperature: -196 ° C
Pretreatment: 400 ° C, 10 hours, nitrogen distribution

(NMR)
Using a general NMR measuring device (device name: Varian600PS, manufactured by Varian), the NMR of the sample was measured under the following conditions.
Frequency: 150.88MHz
Rotor: Zirconia rotor, diameter 3.2 mm
Rotation speed: 7kHz

(Calculation of relative crystallinity)
The XRD pattern of the sample was obtained by the same method as the identification of the crystal structure. In the obtained XRD pattern, 2θ is 12.9 ± 0.2 °, 17.6 ± 0.2 °, 20.3 ± 0.2 °, 25.9 ± 0.2 ° and 30.4, respectively. An XRD peak having a peak top at ± 0.2 ° was obtained, and the total intensity thereof was taken as the crystallinity.

Example 1
Using a TEPBr aqueous solution as a phosphorus source, a TMAdaOH aqueous solution and a [Dab ^- 4] ²⁺ (Br-) ₂ aqueous solution as an SDA source, a phosphorus source, an SDA source, pure water, sodium hydroxide, and an amorphous silicic acid (3) as a silica source. No. sodium silicate) and FAU type zeolite (Y type, cation type: Na type, SiO ₂ / Al ₂ O3 ratio = 5.5 _, aluminosilicate) are mixed to obtain a raw material composition having the following composition. rice field.
SiO ₂ / Al ₂ O ₃ ratio = 25
P / SiO ₂ ratio = 0.1
SDA / SiO ₂ ratio = 0.121
SDA ratio = "Dab-4" / (TMAda + "Dab-4")
= 0.79
OH / SiO ₂ ratio = 0.80
Alkaline / SiO ₂ ratio = 0.78
H ₂ O / SiO ₂ ratio = 28.4

The obtained raw material composition is filled in a closed container, and the raw material composition is obtained by performing hydrothermal treatment at 140 ° C. for 4 days in a state where the closed container is rotated at 10 rpm and the raw material composition is stirred. It was crystallized. The raw material composition after the crystallization step was separated into solid and liquid, and the solid content was washed with pure water and then dried at 70 ° C. to obtain the zeolite of this example.

According to the comparison results of the XRD pattern and the DIFFaX pattern, the zeolite of this example was a small pore zeolite having a crystalline structure having a CHA structure and an AFX structure. Further, according to the composition analysis described above, in the small pore zeolite of this example, the SiO ₂ / Al ₂ O ₃ ratio is 10.2, the P / Al ratio is 0.028, and the P / T ratio is 0. It was .005.

Example 2
The zeolite of this example was obtained by the same method as in Example 1 except that the raw material composition had the following composition.
SiO ₂ / Al ₂ O ₃ ratio = 25
P / SiO ₂ ratio = 0.2
SDA / SiO ₂ ratio = 0.121
SDA ratio = "Dab-4" / (TMAda + "Dab-4")
= 0.79
OH / SiO ₂ ratio = 0.80
Alkaline / SiO ₂ ratio = 0.78
H ₂ O / SiO ₂ ratio = 28.4

According to the comparison results of the XRD pattern and the DIFFaX pattern, the zeolite of this example was a small pore zeolite having a crystalline structure having a CHA structure and an AFX structure. Further, according to the composition analysis described above, in the small pore zeolite of this example, the SiO ₂ / Al ₂ O ₃ ratio is 9.8, the P / Al ratio is 0.044, and the P / T ratio is 0. It was .007.

The XRD pattern of the small pore zeolite of this example is shown in FIG. 1, and the SEM photograph is shown in FIG.

Example 3
The zeolite of this example was obtained by the same method as in Example 1 except that the raw material composition had the following composition.
SiO ₂ / Al ₂ O ₃ ratio = 25
P / SiO ₂ ratio = 0.3
SDA / SiO ₂ ratio = 0.121
SDA ratio = "Dab-4" / (TMAda + "Dab-4")
= 0.79
OH / SiO ₂ ratio = 0.80
Alkaline / SiO ₂ ratio = 0.78
H ₂ O / SiO ₂ ratio = 28.4

According to the comparison results of the XRD pattern and the DIFFaX pattern, the zeolite of this example was a small pore zeolite having a crystalline structure having a CHA structure and an AFX structure. Further, according to the composition analysis described above, in the small pore zeolite of this example, the SiO ₂ / Al ₂ O ₃ ratio is 5.8, the P / Al ratio is 0.050, and the P / T ratio is 0. It was 0.013.

Example 4
The zeolite of this example was obtained by the same method as in Example 1 except that the raw material composition had the following composition.
SiO ₂ / Al ₂ O ₃ ratio = 25
P / SiO ₂ ratio = 0.35
SDA / SiO ₂ ratio = 0.121
SDA ratio = "Dab-4" / (TMAda + "Dab-4")
= 0.79
OH / SiO ₂ ratio = 0.80
Alkaline / SiO ₂ ratio = 0.78
H ₂ O / SiO ₂ ratio = 28.4

According to the comparison results of the XRD pattern and the DIFFaX pattern, the zeolite of this example was a small pore zeolite having a crystalline structure having a CHA structure and an AFX structure. Further, according to the composition analysis described above, in the small pore zeolite of this example, the SiO ₂ / Al ₂ O ₃ ratio is 5.2, the P / Al ratio is 0.071, and the P / T ratio is 0. It was .020.

Example 5 (reference example)
The zeolite of this example was obtained by the same method as in Example 1 except that a TEPOH aqueous solution was used as the phosphorus source instead of the TEPBr aqueous solution and the raw material composition had the following composition.
SiO ₂ / Al ₂ O ₃ ratio = 25
P / SiO ₂ ratio = 0.0025
SDA / SiO ₂ ratio = 0.121
SDA ratio = "Dab-4" / (TMAda + "Dab-4")
= 0.79
OH / SiO ₂ ratio = 0.80
Na / SiO ₂ ratio = 0.78
H ₂ O / SiO ₂ ratio = 28.4

According to the comparison results of the XRD pattern and the DIFFaX pattern, the zeolite of this example was a small pore zeolite having a crystalline structure having a CHA structure and an AFX structure. Further, according to the composition analysis described above, in the small pore zeolite of this example, the SiO ₂ / Al ₂ O ₃ ratio is 11.8, the P / Al ratio is 0.009, and the P / T ratio is 0. It was .001.

Example 6 (reference example)
The zeolite of this example was obtained by the same method as in Example 5 except that the raw material composition had the following composition.
SiO ₂ / Al ₂ O ₃ ratio = 25
P / SiO ₂ ratio = 0.0125
SDA / SiO ₂ ratio = 0.121
SDA ratio = "Dab-4" / (TMAda + "Dab-4")
= 0.79
OH / SiO ₂ ratio = 0.81
Alkaline / SiO ₂ ratio = 0.78
H ₂ O / SiO ₂ ratio = 28.4

According to the comparison results of the XRD pattern and the DIFFaX pattern, the zeolite of this example was a small pore zeolite having a crystalline structure having a CHA structure and an AFX structure. Further, according to the composition analysis described above, in the small pore zeolite of this example, the SiO ₂ / Al ₂ O ₃ ratio is 8.8, the P / Al ratio is 0.003, and the P / T ratio is 0. It was .001.

Comparative Example 1
The zeolite of this example was obtained by the same method as in Example 1 except that no phosphorus source was used and the raw material composition had the following composition.
SiO ₂ / Al ₂ O ₃ ratio = 25
P / SiO ₂ ratio = 0
SDA / SiO ₂ ratio = 0.121
SDA ratio = "Dab-4" / (TMAda + "Dab-4")
= 0.79
OH / SiO ₂ ratio = 0.80
Alkaline / SiO ₂ ratio = 0.78
H ₂ O / SiO ₂ ratio = 28.4

According to the comparison results of the XRD pattern and the DIFFaX pattern, the zeolite of this comparative example was a small pore zeolite having a crystal structure having a CHA structure and an AFX structure. Further, according to the composition analysis described above, in the small pore zeolite of this example, the SiO ₂ / Al ₂ O ₃ ratio was 12.4, but the P / Al ratio was 0 and the P / T ratio. Was 0.

The results of Examples 1 to 6 and Comparative Example 1 are shown in Table 1 below.

Measurement example 1
The small pore zeolites of Example 2 and Comparative Example 1 were calcined in air at 500 ° C. for 10 hours. The evaluation results of the small pore zeolite after calcination are shown in Table 2 below.

From Table 2 above, it was confirmed that the small pore zeolite of Example 2 had a larger BET specific surface area and the same micropore volume as that of the small pore zeolite of Comparative Example 1. From this, it was confirmed that the pores in the crystal structure were not blocked by phosphorus even though the small pore zeolite of Example 2 contained phosphorus.

Measurement example 2
The small pore zeolites of Example 2, Example 4 and Comparative Example 1 were calcined in air at 500 ° C. for 10 hours. Each small pore zeolite after calcination was heat-treated in air at 750 ° C. and 800 ° C. for 1 hour to determine the crystallinity before and after the heat treatment, and the relative crystallinity was determined according to the following formula. The results are shown in Table 3 below.

Relative crystallinity (%) = (crystallinity of small pore zeolite after heat treatment)
/ Crystallinity of small pore zeolite before heat treatment) x 100

From Table 3 above, the small pore zeolites of Example 2 and Example 4 containing phosphorus have a higher degree of relative crystallinity than the small pore zeolite of Comparative Example 1 containing no phosphorus, that is, have heat resistance. It was confirmed that it was expensive. Further, it was confirmed that the small pore zeolite of Example 4 having a higher phosphorus content (that is, a higher P / SiO ₂ ratio shown in Table 1 above) than that of Example 2 has a higher degree of relative crystallinity. did it.

The small pore zeolite of the present invention is, for example, a catalyst for producing a lower olefin from alcohol or ketone, a cracking catalyst, a dewax catalyst, an isomerization catalyst, a nitrogen oxide reduction catalyst from exhaust gas, and a base material for these catalysts. Can be used as. Furthermore, it can be used as a nitrogen oxide reduction catalyst. Moreover, since it has excellent heat resistance, it can be used even under high temperature conditions.

Claims (12)

A small pore zeolite characterized in that the crystal structure is an intergrowth structure of an AFX structure and a CHA structure, and is a crystalline aluminosilicate containing phosphorus in the pores . The small pore zeolite according to claim 1, wherein the phosphorus content is at least one of a phosphate ion and a phosphorus compound . The small pore zeolite according to claim 1 or 2, wherein the molar ratio of phosphorus to aluminum is 0.50 or less. The small pore zeolite according to any one of claims 1 to 3, wherein the ratio of the AFX structure to the total of the CHA structure and the AFX structure in the crystal structure is 0.5 or more and less than 1.0. The small pore zeolite according to any one of claims 1 to 4, wherein the molar ratio of silica to alumina is 5 or more and 30 or less. The small pore zeolite according to any one of claims 1 to 5, wherein the molar ratio of phosphorus to the metal atom constituting the skeleton is 0.0005 or more and 0.1 or less. The method for producing a small pore zeolite according to any one of claims 1 to 6.
It has a crystallization step, which crystallizes a composition containing a silica-alumina source, a phosphorus source, an organic structure-directing agent source, an alkali source and water.
A method for producing a small pore zeolite, wherein the organic structure-directing agent source is a salt containing a cation that directs each of the CHA structure and the AFX structure, and the phosphorus source contains tetraethylphosphonium bromide . The method for producing a small pore zeolite according to claim 7, wherein the molar ratio of phosphorus to silica in the composition is 0.1 or more . The method for producing a small pore zeolite according to claim 7 or 8, wherein the silica-alumina source is crystalline aluminosilicate. The method for producing a small pore zeolite according to any one of claims 7 to 9, wherein the silica-alumina source is a FAU-type zeolite. Claims 7 to 10 are characterized in that the molar ratio of the cations pointing to the AFX structure to the total of the cations pointing to the CHA structure and the cations pointing to the AFX structure of the composition is greater than 0 and 0.79 or less . The method for producing a small pore zeolite according to any one of the above. The method for producing a small pore zeolite according to any one of claims 7 to 11, wherein the composition contains a silica source.

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