JP2019171243A - Zeolite powder - Google Patents

Abstract

To provide a zeolite powder excellent in catalyst activity and catalyst activity maintenance factor as a catalyst for exhaust gas purification.SOLUTION: There is provided a zeolite powder containing 8-membered ring zeolite carrying a transition metal, with a molar ratio of Al amount constituting a zeolite skeleton to Al amount in the zeolite powder of 0.70 to more. There is provided a catalyst for exhaust gas purification containing the zeolite powder. There is provided the catalyst for exhaust gas purification having good performance in which the transition metal is easy to be carried at an optimal position without inhibition by Al existing out of the zeolite skeleton by increasing percentage of Al constituting the zeolite skeleton based on whole amount of Al contained in the zeolite powder, and making diffusion of NOx in a zeolite pore easy.SELECTED DRAWING: Figure 1

Description

The present invention relates to a zeolite powder excellent in catalytic activity and durability (catalytic activity maintenance rate) as an exhaust gas purification catalyst, and to an exhaust gas purification catalyst 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 detoxifies nitrogen oxides (NOx) in exhaust gas from diesel engine automobiles. is there.

  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 to practical use as a catalyst for lower olefin production and exhaust gas purification catalyst utilizing its small pore diameter, particularly as an SCR catalyst for automobile exhaust gas.

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

Conventionally, various studies have been made on zeolites for exhaust gas purification catalysts in order to improve 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 zeolite.
Patent Document 3 describes an AFX zeolite having a (004) plane lattice spacing d of 4.84 to 5.00 and a silica to alumina molar ratio of 10 to 32.
Non-Patent Document 1 describes that copper-supported eight-membered ring zeolite is used as an exhaust gas purification catalyst.

EP 2517775 Japanese Patent Laid-Open No. 2006-169139 Japanese Patent Laid-Open No. 2006-147801

Bulletin of the Chemical Society of Japan 2018, Vol. 91, no. 3,355-361 pages

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

  The present invention has been made in view of the above-described problems of the prior art, and provides a zeolite powder excellent in catalytic activity and catalytic activity maintenance rate as an exhaust gas purification catalyst, and an exhaust gas purification catalyst containing the zeolite powder. The purpose is to do.

The present inventor has repeatedly studied to solve the above problems, and in the zeolite powder containing the transition metal-supported 8-membered ring zeolite, 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 predetermined value or more is excellent in catalyst activity and catalyst activity maintenance rate.
That is, the gist of the present invention is as follows.

A zeolite powder containing an 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 a 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] 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, according to any one of [1] to [4] Zeolite powder.

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

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

  Since the zeolite powder of the present invention is excellent in catalytic activity and durability (catalytic activity maintenance rate) as an exhaust gas purification catalyst, this zeolite powder is used as an exhaust gas purification catalyst for stable and efficient over a long period of time. It is possible to clean the exhaust gas.

2 is a chart of XRD patterns of zeolite powders manufactured in Example 1, Example 2 and Comparative Example 1.

  Hereinafter, typical embodiments for carrying out the present invention will be specifically described. However, the present invention is not limited to the following embodiments as long as the gist of the present invention is not exceeded, and various modifications may be made. Can do.

[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 the above.

<Mechanism>
The 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 constitute the “zeolite skeleton” is present in the zeolite pores, NOx will be present in the zeolite pores when the zeolite powder is used as an exhaust gas purification catalyst. It becomes difficult to enter (difficult to diffuse), and the performance as an exhaust gas purifying catalyst becomes insufficient. In addition, when using zeolite powder as an exhaust gas purification catalyst, it is necessary to support transition metal on zeolite in order to form a catalytic active point. The transition metal loading is hindered by the Al hydroxide, Al oxide, etc., and it becomes difficult to obtain an exhaust gas purifying catalyst 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 of the exhaust gas, the transition metal can be easily supported at an optimal position without being inhibited by Al existing outside the zeolite skeleton, and NOx can be easily diffused into the zeolite pores. A purification catalyst is provided.

<8-membered ring zeolite>
The 8-membered ring oxygen of the 8-membered ring zeolite contained in the zeolite powder of the present invention (hereinafter sometimes referred to as “8-membered ring zeolite of the present invention”) is the oxygen and T element ( Among the pores composed of the elements other than oxygen constituting the skeleton), the one having the largest number of oxygens is shown. For example, in the case where oxygen 12-membered and 8-membered pores exist like MOR type zeolite, it is regarded as 12-membered zeolite.

The 8-membered ring zeolite is a code that defines the structure of the zeolite defined by International Zeolite Associatio (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 structure, preferably AEI type, CHA type, AFX type, LEV type, DDR type, LTA type A RHO type, more preferably from the viewpoint of having an appropriate pore size relative to exhaust gas components, CHA type, AEI type, an AFX type, particularly preferably AFX type.
Whether the zeolite is an 8-membered ring zeolite, in particular, an AFX type zeolite, can be examined by X-ray diffraction as described in the Examples section below.

<Al ratio>
The zeolite powder of the present invention is characterized in that the molar ratio of the amount of Al constituting the zeolite framework to the amount of Al in the zeolite powder (hereinafter sometimes referred to as “Al ratio”) is 0.70 or more. And If the Al ratio is less than 0.70, the effect of improving NOx diffusibility and transition metal loading cannot be obtained sufficiently, and the catalyst activity and catalyst activity maintenance rate as an exhaust gas purifying catalyst are excellent. Zeolite powder cannot be made.

  The Al ratio is preferably as high as possible, and is particularly preferably 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.

In addition, Al ratio can be calculated | required by the method as described in the term of the below-mentioned Example. In addition, 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 charging (increase the dissolution rate of the raw material)
・ Increase the amount of alkali metal hydroxide or alkaline earth metal hydroxide charged (to increase the basicity of the solution)
・ Raise the reaction temperature (react at once)
Thus, it is only necessary to incorporate more Al into the zeolite framework.

<Framework 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 sometimes referred to as “framework Si / Al ratio”) of 4.0 or more and 10.0. The following is preferable. If the skeleton Si / Al ratio is 10.0 or less, an appropriate acid amount exists in the zeolite and good catalytic activity tends to be obtained. On the other hand, if it is 4.0 or more, the skeleton is stable. And the maintenance rate of catalyst activity can be improved.
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, still more preferably 8.0 or less, and particularly preferably 7.0 or less.

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 sometimes referred to as “total Si / Al ratio”). It is preferably 0 or more and 10.0 or less. If the total Si / Al ratio is 10.0 or less, an appropriate acid amount is present in the zeolite, and good catalytic activity tends to be obtained. If it is 4.0 or more, the zeolite skeleton is stabilized and the catalyst is stabilized. The maintenance rate of activity can be improved.
From this viewpoint, the overall 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, still more preferably 8.0 or less, and particularly preferably 7.0 or less.

  The framework Si / Al ratio and the total Si / Al ratio of the zeolite powder can be obtained by the method described in the section of the examples described later. In order to set the framework Si / Al ratio and the entire Si / Al ratio of the zeolite powder within the above ranges, in the method for producing a zeolite powder described later, the Al source and the Si source are divided into the framework Si / Al ratio and the total Si within the above ranges. / Zeolite powder having a total Al mass ratio may be used.

<M / Al molar ratio>
The zeolite powder of the present invention has a molar ratio of transition metal (hereinafter sometimes referred to as “M”) to Al in the zeolite powder (hereinafter sometimes 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, transition metals are optimally arranged in the zeolite and tend to be stabilized. From this viewpoint, the M / Al molar ratio is preferably 0.26 or more, particularly preferably 0.27 or more, and is preferably 0.47 or less, particularly preferably 0.45 or less.

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

  Incidentally, the transition metal supported on the 8-membered ring zeolite of the zeolite powder of the present invention is not particularly limited, but from the viewpoint of characteristics in adsorbent use and catalyst use, usually iron, cobalt, Examples include transition metals belonging to Group 3-12 of the periodic table, such as magnesium, zinc, copper, palladium, iridium, platinum, silver, gold, cerium, lanthanum, praseodymium, titanium, zirconium, and preferably iron, cobalt, copper, etc. It is a transition metal of Group 8, 9, 11 of the periodic table, more preferably Group 8, 11. The transition metal supported on the 8-membered ring zeolite may be one of these, or a combination of two or more transition metals may be supported on the zeolite. Of these transition metals, iron and / or copper is particularly preferable, and copper is particularly preferable.

  The amount of the transition metal supported in the zeolite powder of the present invention is usually 2.0% or more and 6.5% or less as a mass ratio of the transition metal to the mass of the zeolite powder in an anhydrous state, preferably 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, and still more preferably 5.75. % Or less. If the loading amount of transition metal in the zeolite powder is not less than the above lower limit value, the catalytic activity will be good, and if the loading amount of transition metal is not more than the above upper limit value, the durability under high-temperature hydrothermal heat will be good. .

<Method for producing 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”), (2) an alumina source (hereinafter referred to as “Al source”). Obtained by hydrothermal treatment of a raw material mixture comprising (3) organic structure directing agent (SDA), (4) alkali metal hydroxide or alkaline earth metal hydroxide, and (5) water. A method in which a transition metal is supported on an 8-membered ring zeolite is preferable.

  As long as an 8-membered ring structure zeolite is obtained, the organic structure directing agent is not particularly limited, and tetramethylammonium hydroxide (TMAOH), tetraethylammonium hydroxide (TEAOH), and tetrapropylammonium hydroxide. (TPAOH), N, N, N-trimethyl-1-adamantanammonium cation, N, N-diethyl-2,6-dimethylpiperidinium cation, N, N-dimethyl-9-azoniabicyclo [3.3.1] Nonane, 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- Methyl-2-ethylpiperidinium 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-ene-2,3: 5,6- And dipyrrolidine cation. Among these, since Al is arranged at an optimal position, N, N′-diethylbicyclo [2.2.2] oct-7-ene-2,3: 5,6-dipyrrolidine cation, specifically It is preferable to use N, N′-diethylbicyclo [2.2.2] oct-7-ene-2,3: 5,6-dipyrrolidine hydride.

  These organic structure directing 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 oxide, and aluminum oxide, preferably aluminum hydroxide and Y-type zeolite.
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. In other cases, a purity of 95% or more is used, diluted to 5 to 50% with deionized water, or pre-diluted. The amount of alkali metal hydroxide is usually 10 to 70 mol, preferably 15 to 65 mol, more preferably 20 to 60 mol, particularly preferably 100 mol of silica (converted to SiO ₂ ) in the silica source and the alumina source. Is 25 to 55 mol. When the amount of the alkali metal hydroxide is within this range, the 8-membered ring zeolite having an Al ratio according to the present invention tends to be easily obtained.
The water used is preferably high-purity water, for example, ion exchange water (deionized water).

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

Hydrothermal treatment is performed under the following conditions.
The hydrothermal treatment temperature is not particularly limited as long as the zeolite powder according to the present invention can be obtained. However, the hydrothermal treatment is performed under a relatively high temperature condition to form a zeolite skeleton with respect to Al in the zeolite powder. 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. On the other hand, if this temperature is too high and organic substances such as organic structure directing agents (SDA) are decomposed, it tends to be difficult to obtain zeolite with an 8-membered ring structure. In addition, if the hydrothermal treatment time is short, crystallization becomes insufficient, while if it is long, another phase (for example, ANA phase) may be by-produced.
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 zeolite with an 8-membered ring structure.

The AFX zeolite thus obtained may then be calcined. Firing is usually performed using a muffle furnace or a tubular 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 -700 degreeC, Preferably it is 550-650 degreeC, and is 4 to 8 hours normally, Preferably it carries out for 5 to 7 hours.

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

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

  After the transition metal is supported on the 8-membered ring zeolite, it is preferably 300 to 900 ° C, more preferably 350 to 850 ° C, still more preferably 400 to 800 ° C, and 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 performing the calcination, the dispersibility of the transition metal supported on the framework structure of the zeolite can be increased, which is effective in improving the catalytic activity.

[Exhaust gas purification catalyst]
Although there is no restriction | limiting in particular as a use of the zeolite powder of this invention, Since it is excellent in catalyst activity and a catalyst activity maintenance rate, it uses suitably as a SCR catalyst of exhaust gas purification processing, especially a diesel engine automobile exhaust gas, such as a motor vehicle. It is done.

  When the zeolite powder of the present invention is used as a catalyst for exhaust gas purification, the zeolite powder of the present invention may be used as it is, or mixed with a binder such as silica, alumina, clay mineral, etc., and granulated or molded Can also be used. Moreover, it can also be formed into a predetermined shape using a coating method or a forming method, and preferably formed into a honeycomb shape.

  When a catalyst compact 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 produce a slurry, which is made of an inorganic material such as cordierite. The honeycomb-shaped catalyst can be obtained by applying to the surface of the formed body and firing, and preferably applying the honeycomb-shaped formed body at this time.

  When molding a molded product of an exhaust gas purifying catalyst containing the zeolite powder of the present invention, the zeolite powder is usually kneaded with inorganic binders such as silica and alumina, inorganic fibers such as alumina fibers and glass fibers, It is prepared by forming by a compression method or the like, followed by firing. Preferably, a honeycomb-shaped catalyst can be obtained by forming into a honeycomb shape at this time.

  The exhaust gas purifying catalyst containing the zeolite powder of the present invention is effective as an SCR catalyst that purifies nitrogen oxide by contacting exhaust gas containing nitrogen oxide. 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. Moreover, you may use well-known reducing agents, such as nitrogen-containing compounds, such as hydrocarbon, ammonia, and urea. Specifically, the exhaust gas-purifying catalyst containing the zeolite powder of the present invention allows diesel vehicles, gasoline vehicles, stationary power generation / ships / agricultural machinery / construction machinery / motorcycles / aircraft diesel engines, boilers, gas turbines, etc. It is possible to purify nitrogen oxides contained in a wide variety of exhaust gas discharged from the exhaust gas.

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

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited at all by the following example, unless the summary is exceeded.

  Analysis and performance evaluation of the zeolite or Cu-supported AFX zeolite catalyst obtained in the following Examples and Comparative Examples were performed by the following methods.

<Structural analysis of zeolite>
The zeolite structure was determined by an X-ray diffraction method (hereinafter referred to as XRD). In addition, the XRD pattern of each zeolite structure referred to what was made into data on the IZA website. (However, when measuring the actually produced zeolite, it is affected by the growth direction of the zeolite, the ratio of constituent elements, the adsorbed substance, the presence of defects, the dry state, etc. Since a slight shift occurs in the peak position, the same numerical value as each parameter of the structure described in the IZA rules is not obtained, and a width of about 10% is allowed.
As the main peak of the zeolite having the AFX structure, for example, when CuKα ray is used, the peak of 100 plane at 2θ = 7.4 ° ± 0.2 °, 2θ = 8.6 ° ± 0.2 ° Peak at 101 plane, peak at 102 plane at 2θ = 11.5 ° ± 0.2 °, peak at 110 plane at 2θ = 12.8 ° ± 0.2 °, 2θ = 17.7 ° ± 0.2 ° 004 plane peak, 2θ = 25.9 ° ± 0.2 °, and 220 plane peak. )

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

(Device specifications and measurement conditions)
The powder XRD measurement apparatus specifications and measurement conditions are as follows.

<Overall Si / Al ratio and transition metal (Cu) loading amount of zeolite powder>
The analysis of the total Si / Al ratio and the supported amount of transition metal (Cu) supported in the zeolite powder as a standard sample was as follows.
After the zeolite sample was dissolved by heating with an aqueous hydrochloric acid solution, the content (mass%) of silicon atoms and aluminum atoms and the supported quantity (mass%) of transition metal (Cu) atoms were determined by ICP analysis. Then, a calibration curve was created between the fluorescent X-ray intensity of the analytical element in the standard sample and the atomic concentration of the analytical element. From this calibration curve, the content (mass%) of silicon atoms and aluminum atoms and the content (mass%) of transition metal (Cu) atoms 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 content in zeolite framework>
In order to calculate the Si / Al ratio present in the zeolite framework 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 It was measured by analysis.
In addition, as for the attribution of the peak of the solid ²⁹ Si-DD / MAS-NMR spectrum, the peak top has a peak near −110 ppm as Q4 (0Al), the peak at −105 ppm as Q4 (1Al), and the peak as −100 ppm as Q4 ( 2Al), waveform separation was performed, and the Si / Al ratio was calculated. At that time, in solid ²⁹ Si-CP / MAS-NMR, the sample showing 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 a peak area ratio of _{Q4 (nAl)} in the spectrum.
Si / Al = ΣA _{Q4 (nAl)} /Σ0.25 n · A _{Q4 (nAl)} (n = 0 to 4)

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

(Solid ²⁹ Si-CP / MAS-NMR measurement conditions)
Apparatus: Varian NMR Systems 400WB manufactured by Varian
Probe: 7.5 mm HX CP / MAS probe 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
¹ H decoupling frequency: 50 kHz
MAS rotation speed: 5 kHz
Wait time: 3s
Spectral width: 30.5 kHz
Measurement temperature: Room temperature Integration count: 3600 times

(Measurement conditions for solid ²⁹ Si-DD / MAS-NMR)
Apparatus: Varian NMR Systems 400WB manufactured by Varian
Probe: 7.5 mmHX 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
¹ H decoupling frequency: 50 kHz
MAS rotation speed: 5 kHz
Wait time: 600s
Spectral width: 30.5 kHz
Measurement temperature: Room temperature Integration count: 16 times

(Waveform separation analysis)
For each peak of the spectrum after Fourier transform, optimization calculation was performed by a non-linear least square method using the center position, height, and half width of the peak shape created by the mixed waveform of the Lorentz waveform and Gaussian waveform as variable parameters.

<Evaluation of initial catalyst 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 the sized zeolite powder was filled into 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 passed through the catalyst layer at a space velocity SV = 200000 / h.
When the outlet NO concentration becomes constant at 200 ° C,
NO purification rate (%)
= {(Inlet NO concentration)-(Outlet NO concentration)} / (Inlet NO concentration) × 100
The nitrogen oxide removal activity of the catalyst sample was evaluated based on the value of.

<Evaluation of catalyst activity maintenance rate>
The prepared catalyst sample was subjected to a high-temperature steam durability test by the following steam treatment, 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 described above.
(Steam treatment)
Through the packed bed of the catalyst sample, 800 ° C. and 10% by volume of water vapor were passed for 5 hours at a space velocity of SV = 3000 / h.

[Example 1]
In an Erlenmeyer flask, 80.0 g of N, N′-diethylbicyclo [2.2.2] oct-7-ene-2,3: 5,6-dipyrrolidine iodide (manufactured by Kanto Chemical) and 500 g of Water and 400 g of SA10A OH type (manufactured by Mitsubishi Chemical) were mixed as an ion exchange resin.
The mixture was stirred at room temperature for 48 hours (ion exchange). This was filtered, and the filtrate was concentrated under reduced pressure to 238.5 g with an aqueous solution using an evaporator, whereby N, N′-diethylbicyclo [2.2.2] oct-7-ene-2,3: An aqueous solution of 5,6-dipyrrolidine hydroxide was obtained. As a result of titration with a 0.01 M hydrochloric acid aqueous 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] oct-7-ene-2,3: 5,6-dipyrrolidine water as an organic structure directing agent (SDA) As an oxide and an alkali metal hydroxide, 0.76 g of NaOH (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) was mixed, stirred 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) was added as an Al source and a Si source 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 allowed to react 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 collected. The collected crystals were dried at 100 ° C. for 12 hours, and then the XRD of the obtained zeolite powder was measured. As a result, the XRD pattern having peaks and relative intensities at the positions shown in Table 4 was shown by lattice spacing. It was confirmed that 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 organic substances in the zeolite powder 1, the zeolite powder 1 was calcined for 6 hours in an air stream at 600 ° C.
Next, in order to remove Na ions in the calcined zeolite powder 1, it was dispersed in a 1M ammonium nitrate aqueous solution, stirred at 80 ° C., and subjected to ion exchange for 2 hours.
The zeolite was recovered by filtration and washed with ion-exchanged water three times. Thereafter, the above ion exchange and washing were further repeated once.
The obtained zeolite powder was dried at 100 ° C. for 12 hours to obtain a powder containing NH ₄ type zeolite.
The obtained zeolite powder containing NH ₄ type zeolite was calcined in an air stream at 500 ° C. for 2 hours 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 copper acetate solution. The zeolite powder 1A was dispersed in the copper acetate (II) aqueous solution, and ion exchange was performed at 50 ° C. for 2 hours. The 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 zeolite catalyst 1.
The amount of Cu supported on catalyst 1 by XRF analysis was 4.1% by mass. The total Si / Al ratio by XRF analysis was 6.5. The skeleton Si / Al ratio calculated from the waveform separation 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-directing agent used in Example 1, and 0.20 g of NaOH (reagent special grade made by Wako Pure Chemical) as an alkali metal hydroxide are mixed and stirred, dissolved, and transparent. It was set as the solution.
To this solution, 3.51 g of Y-type zeolite (HSZ-350HUA, Si / Al ₂ molar ratio = 10, Tosoh) was added as an Al source and an Si source 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).

  This pre-reaction mixture was placed in a pressure vessel and hydrothermally synthesized for 10 days in a state where it was allowed to stand in an oven at 160 ° C. After this hydrothermal synthesis reaction, the reaction solution was cooled and the crystals produced by filtration were collected. The recovered crystals were dried at 100 ° C. for 12 hours, and then the XRD of the obtained zeolite powder was measured. As a result, an AFX showing an XRD pattern having peaks and relative intensities at positions as shown in Table 5 in terms of lattice spacing. It was confirmed that the type 2 zeolite 2 could be synthesized. An XRD pattern of the zeolite powder 2 containing the zeolite 2 is shown in FIG.

Except that the zeolite powder 2 was used instead of the zeolite powder 1, ion exchange and Cu loading were carried out in the same manner as in Example 1, and similarly a Cu-supported AFX zeolite having a Cu loading of 4.0% by mass was obtained. A catalyst 2 containing was obtained. The total Si / Al ratio by XRF analysis was 5.3. The skeleton Si / Al ratio calculated from the waveform separation 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-azoniabiccyclo [2.2.2] octane hydroxylation from Sachem as organic structure directing agent (SDA) 7.84 g of 20% aqueous solution of the product, 0.22 g of NaOH (reagent special grade manufactured by Wako Pure Chemical Industries) 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) was added as an Al source and an Si source 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).

  This pre-reaction mixture was placed in a pressure vessel and hydrothermally synthesized for 6 days in a state where it was allowed to stand in an oven at 150 ° C. After this hydrothermal synthesis reaction, the reaction solution was cooled and the crystals produced by filtration were collected. The recovered crystals were dried at 100 ° C. for 12 hours, and then the XRD of the obtained zeolite powder was measured. As a result, an AFX showing an XRD pattern having peaks and relative intensities at positions shown in Table 6 in terms of lattice spacing. It was confirmed that the type 3 zeolite 3 could be synthesized. The XRD pattern of this zeolite powder 3 is shown in FIG.

Except that the zeolite powder 3 was used in place of the zeolite powder 1, ion exchange and Cu loading were carried out in the same manner as in Example 1 to obtain a Cu-supported AFX zeolite having a Cu loading of 3.8% by mass. A catalyst 3 containing was obtained. The total Si / Al molar ratio by XRF analysis was 4.0. The skeleton Si / Al ratio calculated from the waveform separation 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 zeolite catalysts 1 to 3 obtained in Example 1 and Comparative Examples 1 and 2, and the evaluation results of the initial catalyst activity and the catalyst activity retention rate. In addition, the Al ratio of the zeolite powders 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 framework Si / Al ratio. Table 7 shows the obtained results.

  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. The reason why the molar ratio exceeded 1 is considered to be the result of an error of about 10% at maximum in the molar ratio calculated by the measurement method. 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 include an error of about 10% at the maximum. Even if the error is taken into consideration, as defined in the present invention, in the comparative example, the maximum Al ratio is less than 0.7, and a high catalyst activity and a high activity maintenance rate cannot be obtained. From the above results, it can be seen that by using the zeolite powder according to the present invention, high catalyst activity and high activity maintenance ratio can be achieved in exhaust gas treatment.

Claims (7)

A zeolite powder comprising an 8-membered ring zeolite carrying a transition metal,
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 0.70 or more.   The zeolite powder according to claim 1, wherein a 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.   The zeolite powder according to any one of claims 1 to 5, wherein the 8-membered ring zeolite is an AFX type zeolite.   An exhaust gas-purifying catalyst comprising the zeolite powder according to any one of claims 1 to 6.

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