JP7091768B2 - Zeolite powder - Google Patents

Description

The present invention particularly relates to a zeolite powder having excellent catalytic activity and durability (catalytic activity retention rate) as a catalyst for purifying exhaust gas, and a catalyst for purifying exhaust gas containing the zeolite powder.
The zeolite powder of the present invention is useful as a selective catalytic reduction (hereinafter referred to as "SCR") catalyst that reduces nitrogen oxides (NOx) in the exhaust gas of a diesel engine vehicle to make them harmless. be.

Zeolites are used in various applications such as catalysts, adsorbents, and separators. In particular, 8-membered ring zeolite (oxygen 8-membered ring zeolite) has been put into practical use as a catalyst for producing a lower olefin utilizing its small pore diameter, a catalyst for purifying exhaust gas, and particularly as an SCR catalyst for automobile exhaust gas.

A general SCR catalyst is made by adhering copper-supported zeolite having a particle size of about several μm to a honeycomb made of ceramics such as cordierite, and NOx in the exhaust gas passes through the honeycomb pores and adheres to the surface thereof. It is decomposed by a reduction reaction in the pores of zeolite.

Conventionally, various studies have been made on the zeolite for the exhaust gas purification catalyst in order to improve the activity, durability and the like.
For example, Patent Document 1 proposes an SCR catalyst made of Cu-supported AFX-type 8-membered ring zeolite.
Patent Document 2 proposes a method for producing a highly crystalline AFX-type zeolite.
Patent Document 3 describes an AFX-type zeolite in which the lattice spacing d of the (004) plane is 4.84 Å or more and 5.00 Å or less, and the molar ratio of silica to alumina is 10 or more and 32 or less.
Non-Patent Document 1 describes that a copper-supported eight-membered ring zeolite is used as an exhaust gas purification catalyst.

European Patent No. 2517775 Japanese Unexamined Patent Publication No. 2016-169139 Japanese Unexamined Patent Publication No. 2016-147801

Bulletin of the Chemical Society of Japan 2018, Vol. 91, No. Pages 3,355-361

Conventional zeolites have problems of low activity as a purification catalyst for exhaust gas of diesel engine automobiles and low durability of the catalyst.

The present invention has been made in view of the above-mentioned problems of the prior art, and provides a zeolite powder having excellent catalytic activity and a catalytic activity retention rate as a catalyst for purifying exhaust gas, and a catalyst for purifying exhaust gas containing the zeolite powder. The purpose is to do.

The present inventor has repeatedly studied to solve the above problems, and in a zeolite powder containing an 8-membered ring zeolite carrying a transition metal, the ratio of the amount of Al constituting the zeolite skeleton to the amount of Al in the zeolite powder is It has been found that a zeolite powder having a value of a predetermined value or more is excellent in catalytic activity and catalytic activity retention rate.
That is, the gist of the present invention is as follows.

A zeolite powder containing 8-membered ring zeolite carrying a transition metal, wherein the molar ratio of the amount of Al constituting the zeolite skeleton to the amount of Al in the zeolite powder is 0.70 or more.

[2] The zeolite powder according to [1], wherein the molar ratio of Si constituting the zeolite skeleton to Al constituting the zeolite skeleton is 4.0 or more and 10.0 or less.

[3] The zeolite powder according to [1] or [2], wherein the molar ratio of the transition metal to Al in the zeolite powder is 0.25 or more and 0.50 or less.

[4] The zeolite powder according to any one of [1] to [3], wherein the transition metal is copper.

[5] Described in any one of [1] to [4], wherein the molar ratio of the total amount of Si in the zeolite powder to the total amount of Al in the zeolite powder is 4.0 or more and 10.0 or less. Zeolite powder.

[6] The zeolite powder according to any one of [1] to [5], wherein the 8-membered ring zeolite is an AFX type zeolite.

[7] An exhaust gas purification catalyst containing the zeolite powder according to any one of [1] to [6].

Since the zeolite powder of the present invention has excellent catalytic activity and durability (catalytic activity maintenance rate) as a catalyst for purifying exhaust gas, this zeolite powder can be used as a catalyst for purifying exhaust gas for a long period of time in a stable and efficient manner. Can purify exhaust gas.

It is a chart of the XRD pattern of the zeolite powder produced in Example 1, Example 2 and Comparative Example 1.

A typical embodiment for carrying out the present invention will be specifically described below, but the present invention is not limited to the following embodiments as long as the gist of the present invention is not exceeded, and the present invention shall be carried out in various modifications. Can be done.

[Zeolite powder]
The zeolite powder of the present invention is a zeolite powder containing an 8-membered ring zeolite carrying a transition metal, and the molar ratio of the amount of Al constituting the zeolite skeleton to the amount of Al in the zeolite powder is 0.70. It is characterized by the above.

<Mechanism>
Zeolite powder contains "zeolite" and "compounds other than zeolite (Al hydroxide, Al oxide, etc. produced during zeolite synthesis)".
If a large amount of Al oxide, Al hydroxide, etc. that do not form the "zeolite skeleton" are present in the zeolite pores, NOx will be generated in the zeolite pores when the zeolite powder is used as a catalyst for purifying exhaust gas. It becomes difficult to enter (difficult to diffuse), and its performance as a catalyst for purifying exhaust gas becomes insufficient. Further, when the zeolite powder is used as a catalyst for purifying exhaust gas, it is necessary to support a transition metal on the zeolite in order to form a catalytic activity point, but it is present in the zeolite pores when the transition metal is supported. The support of the transition metal is hindered by the Al hydroxide, Al oxide, etc., and it becomes difficult to obtain a catalyst for purifying exhaust gas with good performance (catalytic activity and activity retention rate).

Therefore, in the present invention, the amount of Al hydroxide, Al oxide, etc. contained in the zeolite powder is reduced, that is, the ratio of Al constituting the zeolite skeleton to the total amount of Al contained in the zeolite powder. By increasing the size, it is easy to carry the transition metal in the optimum position without being hindered by Al existing outside the zeolite skeleton, and it is easy to diffuse NOx in the zeolite pores, and the exhaust gas has good performance. Provide a purification catalyst.

<8-membered ring zeolite>
The oxygen 8-membered ring of the 8-membered ring zeolite (hereinafter, may be referred to as "8-membered ring zeolite of the present invention") contained in the zeolite powder of the present invention is oxygen and T element (hereinafter, may be referred to as "8-membered ring zeolite of the present invention") forming a zeolite skeleton. Among the pores composed of (elements other than oxygen that compose the skeleton), the one having the largest number of oxygen is shown. For example, when pores of oxygen 12-membered ring and 8-membered ring are present like MOR-type zeolite, it is regarded as 12-membered ring zeolite.

The 8-membered ring zeolite is a code that defines the structure of the zeolite defined by International Zeolite Association (IZA). ABW, ACO, AEI, AEN, AFN, AFT, AFX, ANA, APC, APD, ATN, ATT, ATV, AWO , AWW, BCT, BIK, BRE, CAS, CDO, CHA, DDR, DFT, EAB, EDI, EPI, ERI, ESV, GIS, GOO, IHW, ITE, ITW, JBW, KFI, LEV, LTA, MER, MON , MTF, NSI, OWE, PAU, PHI, RHO, RTE, RTH, RWR, SAS, SAT, SAV, SIV, THO, TSC, UEI, UFI, VNI, YUG, ZON structures are preferable. AEI type, CHA type, AFX type, LEV type, DDR type, LTA type, RHO type, more preferably CHA type, AEI type, AFX type from the viewpoint of having an appropriate pore diameter for exhaust gas components. Yes, and particularly preferably the AFX type.
It should be noted that the fact that the zeolite is an 8-membered ring zeolite, particularly that it is an AFX type zeolite, can be investigated by X-ray diffraction as described in the section of Examples described later.

<Al ratio>
The zeolite powder of the present invention is characterized in that the molar ratio of the amount of Al constituting the zeolite skeleton to the amount of Al in the zeolite powder (hereinafter, may be referred to as “Al ratio”) is 0.70 or more. And. If the Al ratio is less than 0.70, the effect of improving the diffusivity of NOx in the pores and the supportability of the transition metal cannot be sufficiently obtained, and the catalytic activity as a catalyst for purifying exhaust gas and the catalytic activity maintenance rate are excellent. It cannot be a zeolite powder.

The higher the Al ratio, the more preferable it is, and it is particularly preferable that it is 0.80 or more, particularly 0.90 or more. On the other hand, the Al ratio of the zeolite powder of the present invention is theoretically 1 or less when there is no measurement error, but is usually less than 1.

The Al ratio can be obtained by the method described in the section of Examples described later. Further, in order to produce a zeolite powder satisfying the Al ratio of the present invention, in the method for producing a zeolite powder described later: -Reduce the amount of Al at the time of preparation (increase the dissolution rate of the raw material).
・ Increase the amount of alkali metal hydroxide or alkaline earth metal hydroxide to be charged (increase the basicity of the solution)
・ Raise the reaction temperature (react at once)
It is possible to take in more Al in the zeolite skeleton by taking such measures.

<Skeletal Si / Al ratio / Overall Si / Al ratio>
The zeolite powder of the present invention has a molar ratio of Si constituting the zeolite skeleton to Al constituting the zeolite skeleton (hereinafter, may be referred to as “skeleton Si / Al ratio”) of 4.0 or more and 10.0 or more. The following is preferable. If the skeleton Si / Al ratio is 10.0 or less, the zeolite has an appropriate amount of acid and tends to obtain good catalytic activity, while if it is 4.0 or more, the skeleton is stable. It is possible to improve the maintenance rate of catalytic activity.
From this viewpoint, the skeleton Si / Al ratio is more preferably 4.5 or more, further preferably 5.0 or more, and particularly preferably 5.5 or more. On the other hand, it is more preferably 9.0 or less, further preferably 8.0 or less, and particularly preferably 7.0 or less.

Further, the zeolite powder of the present invention has a molar ratio of the total amount of Si in the zeolite powder to the total amount of Al in the zeolite powder (hereinafter, may be referred to as “total Si / Al ratio”). It is preferably 0 or more and 10.0 or less. When the total Si / Al ratio is 10.0 or less, an appropriate amount of acid is present in the zeolite and good catalytic activity tends to be obtained. When 4.0 or more, the zeolite skeleton is stabilized and the catalyst is used. The maintenance rate of activity can be improved.
From this viewpoint, the total Si / Al ratio is more preferably 4.5 or more, further preferably 5.0 or more, and particularly preferably 5.5 or more. On the other hand, it is more preferably 9.0 or less, further preferably 8.0 or less, and particularly preferably 7.0 or less.

The skeleton Si / Al ratio and the total Si / Al ratio of the zeolite powder can be obtained by the method described in the section of Examples described later. In order to set the skeleton Si / Al ratio and the total Si / Al ratio of the zeolite powder in the above range, in the method for producing zeolite powder described later, the Al source and the Si source are set to the skeleton Si / Al ratio and the total Si in the above range. It may be used so that a zeolite powder having a total Al mass ratio can be obtained.

<M / Al molar ratio>
The zeolite powder of the present invention has a molar ratio of a transition metal (hereinafter, may be referred to as “M”) to Al in the zeolite powder (hereinafter, may be referred to as “M / Al molar ratio”). Is preferably 0.25 or more and 0.50 or less. When the M / Al molar ratio is 0.25 or more, good catalytic activity is exhibited, and when it is 0.50 or less, the transition metal tends to be optimally arranged and stabilized in the zeolite. From this viewpoint, the M / Al molar ratio is preferably 0.26 or more, particularly 0.27 or more, and preferably 0.47 or less, particularly 0.45 or less.

The M / Al molar ratio of the zeolite powder can be obtained by the method described in the section of Examples described later. In order to set the M / Al molar ratio of the zeolite powder in the above range, a transition metal is supported so that the zeolite powder having the M / Al molar ratio in the above range can be obtained in the method for producing the zeolite powder described later. Just do it.

The transition metal carried on the 8-membered ring zeolite of the zeolite powder of the present invention is not particularly limited, but iron, copper, and iron are usually used from the viewpoint of characteristics in adsorbent applications and catalyst applications. Examples thereof include transition metals of Group 3-12 of the Periodic Table such as magnesium, zinc, copper, palladium, iridium, platinum, silver, gold, cerium, lanthanum, placeodium, titanium and zirconium, preferably iron, cobalt, copper and the like. It is a transition metal of Group 8, 9 and 11 of the Periodic Table, more preferably Group 8 and 11. The transition metal supported on the 8-membered ring zeolite may be one of these, or two or more kinds of transition metals may be combined and supported on the zeolite. Of these transition metals, iron and / or copper are particularly preferred, and copper is particularly preferred.

The amount of the transition metal carried by the zeolite powder of the present invention is usually 2.0% or more and 6.5% or less as the mass ratio of the transition metal to the mass of the zeolite powder under an anhydrous state, which is preferable. Is 2.25% or more, more preferably 2.5% or more, still more preferably 2.75% or more, preferably 6.25% or less, more preferably 6.0% or less, still more preferably 5.75. % Or less. When the amount of the transition metal supported in the zeolite powder is at least the above lower limit, the catalytic activity is good, and when the amount of the transition metal supported is at least the above upper limit, the durability under high temperature water heat is good. ..

<Manufacturing method of zeolite powder>
The method for producing the zeolite powder of the present invention is not particularly limited, but (1) a silica source (hereinafter sometimes referred to as "Si source") and (2) an alumina source (hereinafter referred to as "Al source"). (3) Organic structure regulator (SDA), (4) Alkaline metal hydroxide or alkaline earth metal hydroxide, and (5) A raw material mixture consisting of water, obtained by hydrothermal treatment. A method in which a transition metal is supported on an 8-membered ring zeolite is preferable.

The organic structure-determining agent is not particularly limited as long as an 8-membered ring-structured zeolite can be obtained, and is tetramethylammonium hydroxide (TMAOH), tetraethylammonium hydroxide (TEAOH) or tetrapropylammonium hydroxide. (TPAOH), N, N, N-trimethyl-1-adamantanammonium cation, N, N-diethyl-2,6-dimethylpiperidinium cation, N, N-dimethyl-9-azonia bicyclo [3.3.1] Nonan, N, N-dimethyl-2,6-dimethylpiperidinium cation, N-ethyl-N-methyl-2,6-dimethylpiperidinium cation, N, N-diethyl-2-ethylpiperidinium cation, N, N-dimethyl-2- (2-hydroxyethyl) piperidinium cation, N, N-dimethyl-2-ethyl piperidinium cation, N, N-dimethyl-3,5-dimethylpiperidinium cation, N -Ethyl-N-methyl-2-ethylpiperidinium cation, 2,6-dimethyl-1-azonium [5.4] decane cation, N-ethyl-N-propyl-2,6-dimethylpiperidinium cation, 1,3-bis (1-adamantyl) imidazolium cation, 1,1'-(1,4-butanidiyl) bis-4-aza-1-azoniabicyclo [2.2.2] octane cation, N, N'- Diethylbicyclo [2.2.2] Oct-7-en-2, 3: 5,6-dipyrrolidine cation and the like can be mentioned. Among these, since Al is arranged at the optimum position, N, N'-diethylbicyclo [2.2.2] octo-7-en-2,3: 5,6-dipyrrolidine cation, specifically. It is preferable to use N, N'-diethylbicyclo [2.2.2] octo-7-en-2,3: 5,6-dipyrrolidinehydride.

These organic structure defining agents may be used alone or in combination of two or more.

Examples of the silica source used in the present invention include Y-type zeolite, sodium silicate, colloidal silica, fumed silica, silicon alkoxide, quartz and the like, preferably sodium silicate and Y-type zeolite.
Examples of the alumina source used in the present invention include Y-type zeolite, aluminum hydroxide, sodium aluminate, aluminum hydroxide, aluminum oxide and the like, preferably aluminum hydroxide and Y-type zeolite.
It should be noted that Y-type zeolite may be used to serve as both a silica source and an alumina source.

The alkali metal hydroxide or alkaline earth metal hydroxide is preferably an alkali metal hydroxide, for example, LiOH, NaOH, KOH, CsOH, Mg (OH) ₂ , Ca (OH) ₂ , Sr ( OH) ₂ or Ba (OH) ₂ , preferably NaOH. In the case of KOH, a purity of 85% or more is used, and in other cases, a purity of 95% or more is used, which is diluted to 5 to 50% with deionized water, or a pre-diluted one is used. The amount of alkali metal hydroxide is usually 10 to 70 mol, preferably 15 to 65 mol, more preferably 20 to 60 mol, and particularly preferably 20 to 60 mol, based on 100 mol of silica (converted to SiO ₂ ) in the silica source and the alumina source. Should be 25-55 mol. When the amount of the alkali metal hydroxide is in this range, the 8-membered ring zeolite having an Al ratio according to the present invention tends to be easily obtained.
Further, the water used is preferably high-purity water, for example, ion-exchanged water (deionized water).

The ratio of the silica source to the alumina source is not particularly limited as long as the zeolite powder according to the present invention can be obtained, but by relatively reducing the amount of the alumina source, the zeolite skeleton with respect to Al in the zeolite powder can be obtained. There is a tendency to easily obtain zeolite powder having a large molar ratio of Al.
Specifically, the amount of alumina (converted to Al) is usually 2 to 10 mol, preferably 3 to 8 mol, with respect to 100 mol of silica (converted to SiO ₂ ) in the silica source and the alumina source. do.
Further, for 100 mol of silica (SiO ₂ ), usually 1 to 20 mol, preferably 2 to 10 mol of an organic structure controlling agent (SDA), and 10 to 10 mol of an alkali metal hydroxide or an alkaline earth metal hydroxide. 50 mol, preferably 20-40 mol, and 1000-4000 mol, preferably 1500-3500 mol of water are used.

The hydrothermal treatment is performed under the following conditions.
The water heat treatment temperature is not particularly limited as long as the zeolite powder according to the present invention can be obtained, but by performing the water heat treatment under relatively high temperature conditions, a zeolite skeleton with respect to Al in the zeolite powder is formed. The molar ratio of Al can be increased.
Specifically, the hydrothermal treatment temperature is usually 100 to 190 ° C, preferably 110 to 180 ° C. The hydrothermal treatment time is usually 6 to 120 hours, preferably 12 to 96 hours. If the hydrothermal treatment temperature is too low, condensation does not proceed, while if the temperature is too high and organic substances such as an organic structure defining agent (SDA) are decomposed, it tends to be difficult to obtain zeolite having an 8-membered ring structure. Further, if the hydrothermal treatment time is short, crystallization becomes insufficient, while if it is long, another phase (for example, ANA phase) may be produced as a by-product.
The hydrothermal reaction is preferably carried out using an autoclave.
After completion of the hydrothermal reaction, solid-liquid separation, washing, and drying are performed to obtain a zeolite having an 8-membered ring structure.

The AFX-type zeolite thus obtained may be subsequently calcined. Firing is usually carried out using a muffle furnace or a tube furnace in an atmosphere of O ₂ : N ₂ = 0: 100 to 100: 0, preferably 20: 80 to 30:70, usually in an air atmosphere, usually 500. It is carried out at about 700 ° C., preferably 550 to 650 ° C., usually for 4 to 8 hours, preferably 5 to 7 hours.

The method for supporting the transition metal on the 8-membered ring zeolite thus obtained is not particularly limited, but is generally used ion exchange method, impregnation support method, precipitation support method, solid phase ion exchange method, and the like. It is preferable to support the transition metal by a CVD method, a spray drying method, or the like, preferably an ion exchange method, a solid phase ion exchange method, an impregnation carrying method, or a spray drying method.

The raw material for the transition metal is not particularly limited, and is usually an inorganic acid salt such as sulfate, nitrate, phosphate, chloride or bromide of the above-mentioned transition metal, or an organic acid such as acetate, oxalate or citrate. Organic metal compounds such as salts, pentacarbonyl and ferrocene are used. Of these, inorganic acid salts and organic acid salts are preferable from the viewpoint of solubility in water, and more specifically, nitrates, sulfates, acetates, hydrochlorides and the like are preferable. In some cases, a colloidal oxide or a fine powder oxide may be used. As the transition metal raw material, two or more kinds of different metal species or compound species may be used in combination.

After the transition metal is supported on the 8-membered ring zeolite, the temperature is preferably 300 to 900 ° C., more preferably 350 to 850 ° C., still more preferably 400 to 800 ° C. for 1 second to 24 hours, preferably 10 seconds to 8 ° C. It is preferable to bake for a time, more preferably about 30 minutes to 4 hours. This calcination is not always necessary, but by calcination, the dispersibility of the transition metal supported on the skeleton structure of zeolite can be enhanced, which is effective in improving the catalytic activity.

[Catalyst for purifying exhaust gas]
The use of the zeolite powder of the present invention is not particularly limited, but since it is excellent in catalytic activity and catalytic activity maintenance rate, it is suitably used as a catalyst for exhaust gas purification treatment of automobiles, especially as an SCR catalyst for exhaust gas of diesel engine automobiles. Will be.

When the zeolite powder of the present invention is used as a catalyst for purifying exhaust gas, the zeolite powder of the present invention may be used as it is in the form of powder, or may be mixed with a binder such as silica, alumina, or clay mineral for granulation or molding. Can also be used by doing. Further, it can be used by molding it into a predetermined shape by using a coating method or a molding method, and preferably it can be molded into a honeycomb shape and used.

When a molded catalyst containing the zeolite powder of the present invention is obtained by a coating method, the zeolite powder is usually mixed with an inorganic binder such as silica or alumina to prepare a slurry, which is then prepared from an inorganic substance such as cordierite. It is produced by applying it to the surface of the molded body and firing it, and preferably, by applying it to the honeycomb-shaped molded body at this time, a honeycomb-shaped catalyst can be obtained.

When molding a molded body of a catalyst for purifying an exhaust gas containing the zeolite powder of the present invention, the zeolite powder is usually kneaded with an inorganic binder such as silica or alumina or an inorganic fiber such as alumina fiber or glass fiber, and is subjected to an extrusion method or an extrusion method. It is produced by molding by a compression method or the like and then firing, and preferably at this time, a honeycomb-shaped catalyst can be obtained by molding into a honeycomb shape.

The exhaust gas purification catalyst containing the zeolite powder of the present invention is effective as an SCR catalyst for purifying nitrogen oxides by contacting exhaust gas containing nitrogen oxides. The exhaust gas may contain components other than nitrogen oxides, and may contain, for example, hydrocarbons, carbon monoxide, carbon dioxide, hydrogen, nitrogen, oxygen, sulfur oxides, and water. Further, known reducing agents such as nitrogen-containing compounds such as hydrocarbons, ammonia and urea may be used. Specifically, the catalyst for purifying exhaust gas containing the zeolite powder of the present invention is used for various diesel engines, boilers, gas turbines, etc. for diesel vehicles, gasoline vehicles, stationary power generation / ships / agricultural machinery / construction machinery / motorcycles / aircraft, etc. It is possible to purify nitrogen oxides contained in a wide variety of exhaust gases emitted from.

The contact conditions between the catalyst and the exhaust gas when using the exhaust gas purification catalyst containing the zeolite powder of the present invention are not particularly limited, but the space velocity of the exhaust gas is usually 100 / h or more, preferably 1000 / h or more. It is h or more, usually 500,000 / h or less, preferably 100,000 / h or less, and the temperature is usually 100 ° C. or higher, preferably 150 ° C. or higher, usually 700 ° C. or lower, preferably 500 ° C. or lower.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded.

The analysis and performance evaluation of the zeolite or Cu-supported AFX-type zeolite catalyst obtained in the following Examples and Comparative Examples were carried out by the following methods.

<Structural analysis of zeolite>
The zeolite structure was determined by X-ray diffraction (hereinafter referred to as XRD). For the XRD pattern of each zeolite structure, refer to the data converted on the IZA homepage. (However, when measuring the actually produced zeolite, the intensity ratio of each peak is affected by the growth direction of the zeolite, the ratio of the constituent elements, the adsorbed substance, the presence of defects, the dry state, etc. Since the peak position is slightly deviated, the same numerical value as each parameter of the structure described in the IZA regulation cannot be obtained, and a width of about 10% is allowed.
As the main peaks of zeolite having an AFX structure, for example, when CuKα rays are used, the peaks are 100 planes at 2θ = 7.4 ° ± 0.2 ° and 2θ = 8.6 ° ± 0.2 °. 101-plane peak, 2θ = 11.5 ° ± 0.2 °, 102-plane peak, 2θ = 12.8 ° ± 0.2 °, 110-plane peak, 2θ = 17.7 ° ± 0.2 ° There are peaks on the 004 plane, and peaks on the 220 plane at 2θ = 25.9 ° ± 0.2 °. )

(Sample preparation)
About 100 mg of a zeolite sample manually crushed using an agate mortar was filled in a sample holder having the same shape so that the sample amount was constant.

(Device specifications and measurement conditions)
The specifications and measurement conditions of the powder XRD measuring device are as follows.

<Overall Si / Al ratio of zeolite powder and transition metal (Cu) carrying amount>
The analysis of the total Si / Al ratio and the amount of the carried transition metal (Cu) carried in the zeolite powder as a standard sample was as follows.
After the zeolite sample was heated and dissolved in an aqueous hydrochloric acid solution, the content (% by mass) of silicon atom and aluminum atom and the carrying amount (mass%) of transition metal (Cu) atom were determined by ICP analysis. Then, a calibration curve of the fluorescent X-ray intensity of the analytical element and the atomic concentration of the analytical element in the standard sample was prepared. From this calibration curve, the content (% by mass) of silicon atom and aluminum atom and the content (mass%) of transition metal (Cu) atom in the zeolite sample were determined by fluorescent X-ray analysis (XRF). ICP analysis was performed using ULTIMA 2C manufactured by HORIBA, Ltd. XRF was performed using EDX-700 manufactured by Shimadzu Corporation.

<Measurement of Si / Al amount in zeolite skeleton>
In order to calculate the Si / Al ratio present in the zeolite skeleton of the zeolite powder obtained by the production method of the present invention, solid ²⁹ Si-DD / MAS-NMR and solid ²⁹ Si-CP / MAS-NMR. Measured by analysis by.
Regarding the attribution of the peaks of the solid ²⁹ Si-DD / MAS-NMR spectrum, the peak with a peak top of around -110 ppm is Q4 (0Al), the peak of -105 ppm is Q4 (1Al), and the peak of -100 ppm is Q4 ( Waveform separation was performed as 2Al), and the Si / Al ratio was calculated. At that time, in the solid ²⁹ Si-CP / MAS-NMR, the sample showing the Q3 peak was subjected to waveform separation including Q3, and the Si / Al ratio was calculated.
The specific calculation formula is as follows. Here, A _{Q4 (nAl)} is the peak area ratio of Q4 (nAl) in the spectrum.
Si / Al = ΣA _{Q4 (nAl)} /Σ0.25n ・ A _{Q4 (nAl)} (n = 0-4)

The measurement conditions and waveform separation of the solid ²⁹ Si-DD / MAS-NMR and the solid ²⁹ Si-CP / MAS-NMR were as follows.

(Solid ²⁹ Si-CP / MAS-NMR measurement conditions)
Equipment: Varian NMR Systems 400WB manufactured by Varian
Probe: 7.5mm Probe for HX CP / MAS Observation nucleus: ²⁹ Si
Measurement method: VACP (Variable Amplitude Cross Polarization) method
²⁹ Si resonance frequency: 79.43 MHz
¹ H resonance frequency: 399.84 MHz
²⁹ Si 90 ° pulse width: 5 μs
^1H decoupling frequency: 50kHz
MAS rotation speed: 5kHz
Waiting time: 3s
Spectral width: 30.5 kHz
Measurement temperature: Room temperature Accumulation frequency: 3600 times

(Measurement conditions for solid ²⁹ Si-DD / MAS-NMR)
Equipment: Varian NMR Systems 400WB manufactured by Varian
Probe: 7.5mm HX CP / MAS probe Observation nucleus: ²⁹ Si
Measurement method: DD (Dipolar Decoupling) / MAS (Magic Angle Spinning) method
²⁹ Si resonance frequency: 79.43 MHz
¹ H resonance frequency: 399.84 MHz
²⁹ Si 90 ° pulse width: 5 μs
^1H decoupling frequency: 50kHz
MAS rotation speed: 5kHz
Waiting time: 600s
Spectral width: 30.5 kHz
Measurement temperature: Room temperature Accumulation frequency: 16 times

(Waveform separation analysis)
For each peak of the spectrum after Fourier transform, optimization calculation was performed by the nonlinear least squares method with the center position, height, and full width at half maximum of the peak shape created by the mixed waveform of Lorentz waveform and Gaussian waveform as variable parameters.

<Evaluation of initial catalytic activity>
The prepared zeolite powder was press-molded, crushed, passed through a sieve, and sized to 0.6 to 1.0 mm. 1 ml of sized zeolite powder was filled in a normal pressure fixed bed flow type reaction tube to form a catalyst layer. The catalyst layer was heated while the gas having the composition shown in Table 3 below was circulated through the catalyst layer at a space velocity SV = 200,000 / h.
When the outlet NO concentration becomes constant at 200 ° C.
NO purification rate (%)
= {(Inlet NO concentration)-(Outlet NO concentration)} / (Inlet NO concentration) x 100
The nitrogen oxide removing activity of the catalyst sample was evaluated by the value of.

<Evaluation of catalytic activity maintenance rate>
The prepared catalyst sample was subjected to a high-temperature steam durability test by the following steam treatment, then press-molded and crushed, passed through a sieve, and sized to 0.6 to 1.0 mm. The catalytic activity of the catalyst sample subjected to the high temperature steam durability test was evaluated in the same manner as above.
(Steam treatment)
Water vapor at 800 ° C. and 10% by volume was passed through the packed bed of the catalyst sample at a space velocity SV = 3000 / h for 5 hours.

[Example 1]
In an Erlenmeyer flask, 80.0 g of N, N'-diethylbicyclo [2.2.2] Oct-7-en-2,3: 5,6-dipyrrolidin iodide (manufactured by Kanto Chemical Co., Inc.) and 500 g. Water and 400 g of SA10A OH type (manufactured by Mitsubishi Chemical Co., Ltd.) as an ion exchange resin were mixed.
The mixture was stirred at room temperature for 48 hours (ion exchange). This is filtered and concentrated under reduced pressure to 238.5 g in an aqueous solution using an evaporator with respect to the filtrate, thereby N, N'-diethylbicyclo [2.2.2] octo-7-en-2,3 :. An aqueous solution of 5,6-dipyrrolidine hydroxide was obtained. As a result of titration with a 0.01 M aqueous hydrochloric acid solution, the concentration was 0.575 mmol / g and the ion exchange rate was 95.7%.

27.0 g of water and 1.7 g of N, N'-diethylbicyclo [2.2.2] octo-7-en-2,3: 5,6-dipyrrolidin water as an organic structure regulator (SDA). 0.76 g of NaOH (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) was mixed and stirred as an oxide and an alkali metal hydroxide, and dissolved to obtain a transparent solution.

To this solution, 3.0 g of Y-type zeolite (CBV760 Si / Al ₂ molar ratio = 30, Zeolist) as an Al source and a Si source was added to obtain a pre-reaction mixture. The ratio of the final mixture was SiO ₂ : Al ₂ O ₃ : NaOH: SDA: H ₂ O = 1: 0.33: 0.38: 0.1: 30 (molar ratio).

This pre-reaction mixture was placed in a 200 ml stainless steel autoclave containing a fluororesin inner cylinder, and reacted at 170 ° C. for 24 hours in a stationary state (hydrothermal synthesis). After this hydrothermal synthesis reaction, the reaction solution was cooled and the crystals produced by filtration were recovered. The recovered crystals were dried at 100 ° C. for 12 hours, and then the XRD of the obtained zeolite powder was measured. It was confirmed that the AFX type zeolite 1 could be synthesized. The XRD pattern of the zeolite powder 1 containing the zeolite 1 is shown in FIG. The overall Si / Al ratio by XRF analysis was 6.5.

In order to remove the organic matter in the zeolite powder 1, the above-mentioned zeolite powder 1 was calcined under an air flow of 600 ° C. for 6 hours.
Next, in order to remove Na ions in the calcined zeolite powder 1, the particles were dispersed in a 1 M aqueous ammonium nitrate solution, stirred at 80 ° C., and ion exchanged for 2 hours.
Zeolites were recovered by filtration and washed with ion-exchanged water three times. Then, the above-mentioned ion exchange and washing were repeated once more.
The obtained zeolite powder was dried at 100 ° C. for ₁₂ hours to obtain a powder containing NH4 type zeolite.
The obtained zeolite powder containing NH4 type zeolite was calcined for ₂ hours under an air flow of 500 ° C. to obtain H type zeolite powder 1A.

1.2 g of copper acetate (II) (monohydrate) (manufactured by Kishida Chemical Co., Ltd.) was dissolved in 36.0 g of water to obtain an aqueous solution of copper acetate. The zeolite powder 1A was dispersed in the cupric acetate (II) aqueous solution, and ion exchange was performed at 50 ° C. for 2 hours. Zeolite (zeolite 1B) was recovered by filtration and washed with ion-exchanged water three times.
The obtained zeolite powder 1B was dried at 100 ° C. for 12 hours and then calcined in air at 500 ° C. for 2 hours to obtain a Cu-supported AFX-type zeolite catalyst 1.
The amount of Cu supported by the catalyst 1 by XRF analysis was 4.1% by mass. The total Si / Al ratio by XRF analysis was 6.5. The skeletal Si / Al ratio calculated from the waveform separations of the solid ²⁹ Si-DD / MAS-NMR and solid ²⁹ Si-CP / MAS-NMR measurement results was 6.1.

[Comparative Example 1]
18.0 g of water, the organic structure regulator used in Example 1, and 0.20 g of NaOH (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) as an alkali metal hydroxide are mixed, stirred, and dissolved to make them transparent. It was made into a solution.
To this solution, 3.51 g of Y-type zeolite (HSZ-350HUA, Si / Al ₂ molar ratio = 10, Tosoh) as an Al source and a Si source was added to obtain a pre-reaction mixture. The ratio of the final mixture was SiO ₂ : Al ₂ O ₃ : NaOH: SDA: H ₂ O = 1: 0.1: 0.1: 0.1: 20 (molar ratio).

The pre-reaction mixture was placed in a pressure-resistant container and allowed to stand in an oven at 160 ° C., and hydrothermal synthesis was carried out for 10 days. After this hydrothermal synthesis reaction, the reaction solution was cooled and the crystals produced by filtration were recovered. After the recovered crystals were dried at 100 ° C. for 12 hours, the XRD of the obtained zeolite powder was measured. As a result, AFX showing an XRD pattern having a peak and a relative intensity at the positions shown in Table 5 on the lattice plane spacing display. It was confirmed that the type zeolite 2 could be synthesized. The XRD pattern of the zeolite powder 2 containing the zeolite 2 is shown in FIG.

Ion exchange and Cu were carried out in the same manner as in Example 1 except that zeolite powder 2 was used instead of zeolite powder 1, and a Cu-supported AFX-type zeolite having a Cu-supported amount of 4.0% by mass was similarly obtained. A catalyst 2 containing the mixture was obtained. The total Si / Al ratio by XRF analysis was 5.3. The skeletal Si / Al ratio calculated from the waveform separations of the solid ²⁹ Si-DD / MAS-NMR and solid ²⁹ Si-CP / MAS-NMR measurement results was 9.5.

[Comparative Example 2]
22.5 g of water and 1,1'-(1,4-butanydiyl) bis-4-aza-1-azoniabicyclo [2.2.2] oxide hydroxide manufactured by Sachem as an organic structure regulator (SDA). 7.84 g of a 20% aqueous solution of the product, 0.22 g of NaOH (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) as an alkali metal hydroxide, and 8.60 g of sodium silicate No. 3 manufactured by Kishida Chemical Co., Ltd. were mixed and stirred.
To this solution, 0.78 g of Y-type zeolite (CBY100, Si / Al ₂ molar ratio = 5.1, Zeolist) as an Al source and a Si source was added to obtain a pre-reaction mixture. The ratio of the final mixture was SiO ₂ : Al ₂ O ₃ : NaOH: SDA: H ₂ O = 1: 0.33: 0.7: 0.1: 25 (molar ratio).

The pre-reaction mixture was placed in a pressure-resistant container and allowed to stand in an oven at 150 ° C., and hydrothermal synthesis was carried out for 6 days. After this hydrothermal synthesis reaction, the reaction solution was cooled and the crystals produced by filtration were recovered. After the recovered crystals were dried at 100 ° C. for 12 hours, the XRD of the obtained zeolite powder was measured. As a result, AFX showing an XRD pattern having a peak and a relative intensity at the positions shown in Table 6 on the lattice spacing display. It was confirmed that the type zeolite 3 could be synthesized. The XRD pattern of this zeolite powder 3 is shown in FIG.

Except for using zeolite powder 3 instead of zeolite powder 1, ion exchange and Cu bearing were carried out in the same manner as in Example 1, and a Cu-supported AFX-type zeolite having a Cu-supporting amount of 3.8% by mass was similarly obtained. A catalyst 3 containing was obtained. The total Si / Al molar ratio by XRF analysis was 4.0. The skeletal Si / Al ratio calculated from the waveform separations of the solid ²⁹ Si-DD / MAS-NMR and solid ²⁹ Si-CP / MAS-NMR measurement results was 7.1.

Table 7 shows the analysis results of the Cu-supported AFX-type zeolite catalysts 1 to 3 obtained in Examples 1 and Comparative Examples 1 and 2 and the evaluation results of the initial catalytic activity and the catalytic activity maintenance rate. Moreover, the Al ratio of the zeolite powder obtained in Example 1 and Comparative Examples 1 and 2 was calculated from the value of the total Si / Al ratio and the value of the skeleton Si / Al ratio. The results obtained are shown in Table 7.

As can be seen from Table 7, the molar ratio of the amount of Al constituting the zeolite skeleton to the amount of Al in the zeolite powder was 1.06. It is considered that the reason why the molar ratio exceeds 1 is that the molar ratio calculated by the measurement method has an error of up to about 10%. On the other hand, the result of the molar ratio of the amount of Al constituting the zeolite skeleton to the amount of Al in the zeolite powder of the zeolite powder according to Comparative Example 1 and Comparative Example 2 may also contain an error of up to about 10%. As specified in the present invention even when the error is taken into consideration, the Al ratio is less than 0.7 at the maximum in the comparative example, and high catalytic activity and high activity retention rate are not obtained. From the above results, it can be seen that high catalytic activity and high activity retention rate can be achieved in exhaust gas treatment by using the zeolite powder according to the present invention.

Claims (6)

A zeolite powder containing an 8-membered ring zeolite on which a transition metal is supported.
The 8-membered ring zeolite is an AFX type zeolite,
A zeolite powder in which the molar ratio of the amount of Al constituting the zeolite skeleton to the amount of Al in the zeolite powder is 0.90 or more. The zeolite powder according to claim 1, wherein the molar ratio of Si constituting the zeolite skeleton to Al constituting the zeolite skeleton is 4.0 or more and 10.0 or less. The zeolite powder according to claim 1 or 2, wherein the molar ratio of the transition metal to Al in the zeolite powder is 0.25 or more and 0.50 or less. The zeolite powder according to any one of claims 1 to 3, wherein the transition metal is copper. The zeolite powder according to any one of claims 1 to 4, wherein the molar ratio of the total amount of Si in the zeolite powder to the total amount of Al in the zeolite powder is 4.0 or more and 10.0 or less. body. An exhaust gas purification catalyst containing the zeolite powder according to any one of claims 1 to 5 .

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