JP6988111B2 - Method for producing oxygen 8-membered ring zeolite - Google Patents

Description

The present invention relates to a method for producing an oxygen 8-membered ring zeolite, and a method for using the zeolite produced by the method as a catalyst for producing a lower olefin and a catalyst for treating exhaust gas.

Zeolites are used in various applications such as catalysts, adsorbents, and separators. In particular, oxygen 8-membered ring zeolite is expected as a catalyst for producing lower olefins and a catalyst for treating automobile exhaust gas by utilizing its small pore diameter.

Examples of the oxygen 8-membered ring zeolite include AFX, ERI, KFI, CHA, RHO, and AEI in the structural code defined by the International Zeolites Association (hereinafter, this may be abbreviated as "IZA").

As a method for producing an oxygen 8-membered ring zeolite, various production methods using a structure-defining agent (mainly a quaternary ammonium salt) suitable for the structure have been reported. For example, as a method for producing AFX-type zeolite, a production method using a quinuclidine derivative as a structure-defining agent has been reported (Patent Document 1).
Further, as a method for producing an AFX-type zeolite having a relatively high silica composition, a method for producing a 1,3-di (1-adamantyl) imidazolium cation as a structure-determining agent is disclosed (Patent Document 2). On the other hand, as a method for producing an ERI-type zeolite, a production method using two types of a hexamethonium cation and a tetraethylammonium cation as a structure-determining agent is disclosed (Patent Document 3). As a method for producing KFI-type zeolite, a production method using 18-crown-6 crown ether as a structure-determining agent is disclosed (Non-Patent Document 1). Further, as a method for producing CHA-type zeolite, a production method using N, N, N-trimethyl-1-adamantanammonium cation (Patent Document 4) and a production method using a tetraethylammonium cation (Patent Document 5) are disclosed. Has been done.

However, the above-mentioned known methods have various problems, and satisfactory results are not always obtained. For example, in the methods described in Patent Documents 1 to 4 and Non-Patent Document 1, the quaternary ammonium salt or ether as a structure-determining agent is expensive, so that the production cost of the oxygen 8-membered ring zeolite is high, and industrial production is performed. In that respect, it is not practical. Further, although the method described in Patent Document 5 uses an inexpensive quaternary ammonium salt, it takes a long time (7 days) for crystallization, so that this is also practical in terms of industrial production. I can't stand it.

U.S. Pat. No. 4,508,837 Japanese Unexamined Patent Publication No. 2016-147801 U.S. Pat. No. 7,344,694 U.S. Pat. No. 4,454,538 International Publication WO2016 / 096653 Pamphlet

Zeolites, 17, 328-333 (1996)

The present invention produces an oxygen 8-membered ring zeolite at low cost, in a short time and in a high yield by using an inexpensive quaternary ammonium salt and a general-purpose alkaline (earth) metal source. The challenge is to provide a method.

As a result of diligent studies to solve the above problems, the present inventors have added zeolite having a relatively low framework density as an aluminum source, oxygen 8-membered ring zeolite as a seed crystal, and a structure-defining agent in a hydrothermal synthesis mixture. By using a quaternary ammonium salt composed of a substituent having 4 or less carbon atoms and setting the mixing ratio of the alkaline (earth) metal and the quaternary ammonium salt to a predetermined ratio, the oxygen 8-membered ring zeolite can be simply obtained. We have found that it can be produced as a single component and in a high yield, and have reached the present invention.

That is, the gist of the present invention is as follows.
[1] Oxygen 8-membered ring zeolite by hydrothermal synthesis of a mixture containing a silicon source, an aluminum source, an alkali metal element source and / or an alkaline earth metal element source, a quaternary ammonium salt, water and seed crystals. A method for producing an oxygen 8-membered ring zeolite, which comprises satisfying the following (i) to (v) in the method for producing the above.
(I) The aluminum source contains at least a zeolite (I) having a Framework density of 16.0 T / 1000 Å or less.
(Ii) Oxygen 8-membered ring zeolite (II) is contained as the seed crystal.
(Iii) The quaternary ammonium salt contains at least a quaternary ammonium salt composed of only independent substituents having 4 or less carbon atoms.
(Iv) The total molar ratio of the alkali metal atom to the alkali earth metal atom to silicon in the mixture is less than 0.40.
(V) The molar ratio of the quaternary ammonium salt to silicon in the mixture is 0.30 or less.
[2] The method for producing an oxygen 8-membered ring zeolite according to [1], wherein the oxygen 8-membered ring zeolite having a molar ratio of silicon to aluminum of 3.0 or more and 6.0 or less is produced.
[3] It is characterized by producing at least one oxygen 8-membered ring zeolite selected from AFX, ERI, KFI, LEV, SAS, SAV, PAU, RHO, and LTA with a code specified by the International Zeolite Association (IZA). The method for producing an oxygen 8-membered ring zeolite according to [1] or [2].
[4] The total molar ratio of the alkali metal atom, the alkaline earth metal atom and the quaternary ammonium salt to silicon in the mixture is 0.50 or less [1] to [3]. ] The method for producing an oxygen 8-membered ring zeolite according to any one of the above items.
[5] The oxygen 8-membered ring zeolite according to any one of [1] to [4], wherein the molar ratio of silicon to aluminum of the zeolite (I) is 2.0 or more and 10 or less. Production method.
_{[6] The molar ratio of SiO 2} derived from the zeolite (I) to SiO ₂ when all the silicon in the mixture is SiO ₂ is 0.50 or more [1]. ] To [5], the method for producing an oxygen 8-membered ring zeolite according to any one of the following items.
[7] The oxygen according to any one of [1] to [6], wherein the zeolite (I) contains at least a zeolite having a code defined by the International Zeolite Association (IZA) and is FAU. Method for producing 8-membered ring zeolite.
[8] A method for producing an oxygen 8-membered ring zeolite by the production method according to any one of [1] to [7], and using this as a catalyst for producing a lower olefin.
[9] A method for producing an oxygen 8-membered ring zeolite by the production method according to any one of [1] to [7], and using this as a catalyst for exhaust gas treatment.

According to the present invention, an oxygen 8-membered ring zeolite can be efficiently produced by using a quaternary ammonium salt which is easy to synthesize and inexpensive, while suppressing the production cost. Further, the produced oxygen 8-membered ring zeolite can be suitably used as a catalyst for producing a lower olefin or a catalyst for treating exhaust gas from an automobile.

It is an XRD pattern of the AFX type zeolite obtained in Example 1.

Hereinafter, typical embodiments for carrying out the present invention will be specifically described, 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.

Hereinafter, the present invention will be described in detail.

[Oxygen 8-membered ring zeolite]
Hereinafter, the oxygen 8-membered ring zeolite obtained by the production method of the present invention (hereinafter, may be referred to as “zeolite of the present invention”) will be described.

<Structure>
The zeolite of the present invention is a porous crystalline compound that usually has crystallinity and forms open regular micropores (hereinafter, may be simply referred to as “pores”), and has four surfaces. It has a structure in which ₄ TO units having a body structure (T means an element other than oxygen constituting zeolite) share an oxygen atom and are three-dimensionally linked.

The oxygen 8-membered ring zeolite of the present invention is a structural code (Framework Type Code) defined by the International Zeolite Association (IZA), and is ABW (19.0), AEI (14.8), AEN (19.7), AFN. (17.4), AFT (14.9), AFX (14.7), APC (18.0), APD (19.8), ATN (17.4), ATT (16.7), ATV ( 19.9), AWO (18.3), AWW (16.7), BIK (20.3), BRE (17.3), CAS (20.6), CDO (19.3), CHA (14) .5), DDR (17.6), EAB (15.5), ERI (15.7), ESV (17.3), IHW (18.7), ITE (16.3), ITW (18. 1), KFI (14.6), LEV (15.2), LTA (12.9), MER (16.0), MON (18.1), MTF (20.6), PAU (15.5) ), PHI (15.8), RHO (14.1), RTE (17.3), RTH (16.6), SAS (15.3), SAT (16.6), SAV (14.4). , TSC (12.1), UFI (15.4) and the like. It is preferably AEI, AFX, CHA, ERI, KFI, LEV, SAS, SAV, PAU, RHO, LTA, more preferably AFX, ERI, KFI, LEV, SAS, SAV, PAU, RHO, LTA, and further. AFX, ERI and KFI are preferable, and AFX is particularly preferable. The numerical value in parentheses is the framework density of zeolite (unit: T / 1000A ³ ). The framework density means the number of atoms T other than oxygen forming a skeleton existing per unit volume (1000A ³ ) of zeolite, and this value is determined by the structure of zeolite. The relationship between the framework density and the structure of zeolite is shown in the data collection on zeolite (Atlas of Zeolite Framework Types, Sixth Revised Edition 20007, ELSEVIER) compiled by the Structure Commission of IZA. ..
As the oxygen 8-membered ring zeolite of the present invention, a zeolite containing d6r defined as a composite building unit by the International Zeolite Association (IZA) in its skeleton is preferable.

<Components>
The zeolite of the present invention is an aluminosilicate containing at least aluminum. The zeolite of the present invention contains 70 mol% or more of silicon atoms in T atoms. In addition to aluminum, the zeolite of the present invention may contain at least one element M selected from the group consisting of boron, gallium, and iron. The element M is incorporated into the skeleton as a T atom of zeolite, becomes an active point of moderate acid strength, and functions as an active point of a conversion reaction of an organic compound such as methanol or ethylene.

The zeolite of the present invention is preferably an aluminosilicate in which the T atom is composed of silicon and aluminum, a boroaluminosilicate, a galloaluminosilicate, a ferialminosilicate, a borogalloaluminosilicate, and a boroferrialosilicate. It is preferably an aluminosilicate, a boroaluminosilicate, a ferrialminosilicate, and more preferably an aluminosilicate in which the T atom is composed of silicon and aluminum.

Moreover, the zeolite of the present invention may contain other elements in addition to the above-mentioned elements. Examples of other elements include, but are not limited to, zinc (Zn), germanium (Ge), titanium (Ti), zirconium (Zr), tin (Sn) and the like. These constituent elements may be one kind or two or more kinds.

<Mole ratio of aluminum to silicon>
The molar ratio of silicon to aluminum (Si / Al) of the zeolite of the present invention is not particularly limited, but is usually 2.0 or more, preferably 3.0 or more, more preferably 3.5 or more, still more preferable. Is 4.0 or more, particularly preferably 4.5 or more, usually 100 or less, preferably 25 or less, more preferably 10 or less, still more preferably 8.0 or less, and particularly preferably 6.0 or less. By setting the molar ratio of silicon to aluminum in the above range, when used as a catalyst, organic compound raw materials such as ethylene and methanol can be efficiently converted by the acid points with strong acid strength derived from Al. Therefore, it is preferable. In addition, it is possible to prevent phenomena such as catalyst deactivation due to cork adhesion, desorption of T atoms other than silicon from the skeleton, and a decrease in acid strength per acid point.

<Mole ratio of total element M to silicon>
The molar ratio (Si / M) of silicon to the total of the elements M of the zeolite of the present invention is not particularly limited, but is usually 5 or more, preferably 10 or more, more preferably 30 or more, still more preferably 50. As mentioned above, there is usually no upper limit. When the M / Si molar ratio is in the above range, the desorption of the element M from the skeleton can be suppressed.

The content of Si, Al and other elements M (B, Fe, Ga) of the zeolite of the present invention can usually be measured by ICP elemental analysis or fluorescent X-ray analysis. X-ray fluorescence analysis creates a calibration curve of the fluorescent X-ray intensity of the analytical element in the standard sample and the atomic concentration of the analytical element, and this calibration curve is used for silicon in the zeolite sample by X-ray fluorescence analysis (XRF). The contents of atoms, aluminum, gallium, and iron atoms can be determined. Since the fluorescent X-ray intensity of the boron element is relatively small, it is preferable to measure the content of the boron atom by ICP elemental analysis.

<Phosphorus content>
The phosphorus content contained in the crystals of the zeolite of the present invention is not particularly limited, but is preferably as low as possible, usually 500 ppm or less, preferably 300 ppm or less, more preferably 100 ppm or less, and most preferably 0 ppm. .. By setting the phosphorus content in the zeolite crystal to the above range, a sufficient specific surface area can be obtained, high intra-crystal diffusivity of the hydrocarbon component can be obtained, and the conversion activity of the organic compound raw material is high. Become. Since side reactions at phosphorus-derived acid sites are suppressed, the yield of lower olefins can be improved. The zeolite of the present invention may contain a part of phosphorus in and / or outside the skeleton of the zeolite, but it is preferably contained only outside the skeleton, and more preferably not contained. be.

<Total acid amount>
The total acid amount of the zeolite of the present invention (hereinafter referred to as the total acid amount) is the amount of acid points existing in the crystal pores of the zeolite and the amount of the crystal outer surface acid points of the zeolite (hereinafter referred to as outer surface acid). It is the sum of (called quantity). The total acid amount is not particularly limited, but is usually 0.010 mmol / g or more, preferably 0.10 mmol / g or more, more preferably 0.50 mmol / g or more, still more preferably 1.0 mmol / g or more. Is. Further, it is usually 3.0 or less, preferably 2.5 mmol / g or less, more preferably 2.0 mmol / g or less, still more preferably 1.5 mmol / g or less. By setting the total amount of acid in the above range, the conversion activity of the organic compound raw material can be easily secured, the coke formation inside the pores of the zeolite is suppressed, and the diffusibility in the crystal of the molecule is increased, so that the lower olefin can be used. It is preferable in that it can promote the production. Further, even when it is used as a catalyst for exhaust gas treatment, it is preferable because it has many active sites as a catalyst and has high purification performance for exhaust gas containing nitrogen oxides.

Here, the total acid amount is calculated from the desorption amount of ammonia temperature-programmed desorption _(NH 3 -TPD). Specifically, as a pretreatment, the zeolite is dried under vacuum at 500 ° C. for 30 minutes, and then the pretreated zeolite is brought into contact with an excess amount of ammonia at 100 ° C. to adsorb the ammonia to the zeolite. Excess ammonia is removed from the zeolite by vacuum drying the obtained zeolite at 100 ° C. (or contacting it with water vapor at 100 ° C.). Next, the zeolite on which ammonia is adsorbed is heated at a heating rate of 10 ° C./min in a helium atmosphere, and the amount of ammonia desorbed at 100-600 ° C. is measured by mass spectrometry. The amount of ammonia desorbed per zeolite is defined as the total acid amount. However, the total amount of acid in the present invention is the total area of the waveform having the peak top of 240 ° C. or higher after the TPD profile is waveform-separated by the Gaussian function. This "240 ° C." is an index used only for determining the position of the peak top, and does not mean to obtain the area of the portion above 240 ° C. As long as the peak top is a waveform of 240 ° C. or higher, the "area of the waveform" is the total area including the portion other than 240 ° C. When there are a plurality of waveforms having peak tops at 240 ° C. or higher, the sum of the areas thereof is used.
The total amount of acid in the present invention does not include the amount of acid derived from a weak acid point having a peak top of less than 240 ° C. This is because it is not easy to distinguish between adsorption derived from a weak acid point and physical adsorption in the TPD profile.

<Amount of acid on the outer surface>
The amount of acid on the outer crystal surface of the zeolite of the present invention is not particularly limited, but is usually 8% or less, preferably 5% or less, more preferably 3% or less, still more preferable, with respect to the total acid amount of the zeolite. Is 1% or less, most preferably 0%. If the amount of outer surface acid is too large, there is a tendency for the selectivity of the lower olefin to decrease due to side reactions that occur at the outer surface acid spots. It is presumed that this is because the reaction to generate hydrocarbons other than the target substance proceeds at the acid point on the outer surface. Further, it is presumed that the lower olefin produced in the pores of the zeolite further reacts at the acid point on the outer surface, which is one of the causes of the decrease in selectivity.

The value of the amount of acid on the outer surface of the zeolite of the present invention can be measured by the method described in International Publication No. 2010/128644 pamphlet.

The method for adjusting the amount of acid on the outer surface of the zeolite within the above range is not particularly limited, but usually includes methods such as silylation of the outer surface of the zeolite, steam treatment, and heat treatment. Further, a method of binding the binder and the outer surface acid point of the zeolite when molding the zeolite can be mentioned.

<Ion exchange site>
The ion exchange site of the zeolite of the present invention is not particularly limited. Usually, it is a proton (hereinafter, also referred to as "proton type" or "H type"), or partly an alkali metal such as lithium (Li), sodium (Na), potassium (K), cesium (Cs); magnesium ( It is a metal ion such as an alkaline earth metal such as Mg), calcium (Ca), strontium (Sr), and barium (Ba). The ion exchange site is preferably proton, sodium, potassium, calcium, more preferably proton, sodium, potassium, still more preferably proton, from the viewpoint of improving molecular diffusivity by reducing the metal occupied volume in the cage space. It is sodium, particularly preferably a proton. Hereinafter, for example, those exchanged with Na ions may be referred to as "Na type". Those ion-exchanged with ammonium (NH ₄ ) are usually treated in the same manner as the proton type because ammonia is eliminated under high temperature reaction conditions.

The total content of the alkali metal and the alkaline earth metal in the zeolite of the present invention is not particularly limited, but is usually 0.005% by mass or more, preferably 0.01% by mass or more, and more preferably 0.1% by mass. % Or more, usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less. By setting the total content of alkali metal and alkaline earth metal within the above range, the acid amount of zeolite and the cage space volume can be adjusted, so that coke accumulation during the reaction can be suppressed. preferable. It is also preferable in that the thermal / hydrothermal stability is high and deterioration can be suppressed.

<Containing metal>
In addition to these ion exchange sites, even if alkali metals such as Na and K; alkaline earth metals such as Mg and Ca; and transition metals such as Cr, Cu, Ni, Fe, Mo, W, Pt and Re are supported. good. Here, the metal support can usually be carried out by an impregnation method such as an equilibrium adsorption method, an evaporation dry solid method, or a pore filling method.
The total amount of the alkali metal and the alkaline earth metal in the zeolite of the present invention is preferably in the above range even when it is contained in other than the ion exchange site.

<Average primary particle size>
The average primary particle size of the zeolite of the present invention is not particularly limited, but is usually 0.03 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, still more preferably 0.15 μm or more, particularly. It is preferably 0.20 μm or more, usually 10 μm or less, preferably 5 μm or less, more preferably 2 μm or less, still more preferably 1 μm or less, and particularly preferably 0.40 μm or less. Within the above range, the diffusibility in the zeolite crystal and the catalytic effectiveness coefficient in the catalytic reaction are sufficiently high, the zeolite crystallinity is sufficient, and the water thermal stability is high, which is preferable.
The average primary particle size in the present invention corresponds to the particle size of the primary particles. Therefore, it is different from the particle size of the aggregate measured by a light scattering method or the like. The average particle size is determined by arbitrarily measuring 50 or more particles in the observation of particles with a scanning electron microscope (hereinafter abbreviated as "SEM") or a transmission electron microscope (hereinafter abbreviated as "TEM"). Then, it is obtained by averaging the particle diameters of the primary particles. If the particle is rectangular, measure the long and short sides of the particle (without measuring the depth), calculate the average of the sum (that is, (long side + short side) ÷ 2), and then calculate the particle of the particle. The diameter.

<BET specific surface area>
The BET specific surface area of the zeolite of the present invention is not particularly limited, but is usually 300 m ² / g or more, preferably 400 m ² / g or more, more preferably 500 m ² / g or more, and usually 1000 m ² / g. Hereinafter, it is preferably 800 m ² / g or less, and more preferably 750 m ² / g or less. Within the above range, the number of active sites existing on the inner surface of the pores is sufficiently large, and the catalytic activity is high, which is preferable. The BET specific surface area can be measured by a measuring method according to JIS8830 (method for measuring the specific surface area of powder (solid) by gas adsorption). Nitrogen is used as the adsorbed gas, and the BET specific surface area is determined by the one-point method (relative pressure: p / p _{0 = 0.30).}

[Manufacturing method of oxygen 8-membered ring zeolite]
The method for producing an oxygen 8-membered ring zeolite of the present invention is a mixture containing a silicon source, an aluminum source, an alkali metal element source and / or an alkaline earth metal element source, a quaternary ammonium salt, water and seed crystals. It is a method for producing an oxygen 8-membered ring zeolite by hydrothermal synthesis, and is characterized by satisfying the following (i) to (v).
(I) The aluminum source contains at least a zeolite (I) having a Framework density of 16.0 T / 1000 Å or less.
(Ii) Oxygen 8-membered ring zeolite (II) is contained as the seed crystal.
(Iii) The quaternary ammonium salt contains at least a quaternary ammonium salt composed of only independent substituents having 4 or less carbon atoms.
(Iv) The total molar ratio of the alkali metal atom to the alkali earth metal atom to silicon in the mixture is less than 0.40.
(V) The molar ratio of the quaternary ammonium salt to silicon in the mixture is 0.30 or less.

The oxygen 8-membered ring zeolite of the present invention can be produced according to a conventional method for hydrothermal synthesis of zeolite except for the above-mentioned characteristics. That is, a mixture of a crystal precursor containing a silica source, an aluminum source, an alkali metal element source and / or an alkaline earth metal element source, and a quaternary ammonium salt, water, and a seed crystal is prepared and hydrothermally synthesized. It can be synthesized by a method.

Hereinafter, an example of the manufacturing method will be described.

<Ingredients of the mixture>
(A) Silicon source The silica source used in the present invention is not particularly limited, and silicates such as fine powder silica, silica sol, silica gel, silicon dioxide and water glass, alkoxides of silicon such as tetramethoxysilane and tetraethoxysilane, and halides of silicon. And so on. Further, silica-containing zeolite such as FAU-type zeolite or CHA-type zeolite may be used as the silica source.
These silica sources may be used alone or in combination of two or more.
Among these silica raw materials, fine powder silica, silica sol, water glass, silica-containing zeolite and the like are preferably used in terms of cost advantage and ease of handling, and more preferably silica sol in terms of reactivity. , Water glass, silica-containing zeolite are used.

(B) Aluminum source The aluminum source contains at least zeolite (I) having ^{a Framework density of 16.0 T / 1000 A 3 or less.} Zeolites with a relatively low skeleton density of 16.0 T / 1000 A ³ or less have high solubility in an alkaline raw material mixture, and are therefore easily decomposed into nanoparts constituting the skeleton, and the oxygen 8-membered ring of the present invention. The contribution of zeolite to the formation of crystal structure is increased. Framework density is 16.0T / 1000A ³ or less, preferably 15.0T / 1000A ³ or less, more preferably 14.8T / 1000A ³ or less, still more preferably 14.6T / 1000A ³ or less, and particularly preferably 14.4 or less. Is. The Framework density is usually 10.0T / 1000A ³ or more, preferably 11.0T / 1000A ³ , and more preferably 12.0T / 1000A ³ or more.

Zeolites with a Framework density of 16.0T / 1000A ³ or less include AEI (14.8), AFG (15.9), AFX (14.7), BEA (15.1), BEC (13.9), etc. BOG (15.6), CHA (14.5), EAB (15.5), EMT (12.9), ERI (15.7), ETR (14.7), FAR (15.8), FAU (12.7), FRA (15.6), GIS (15.3), GIU (15.9), GME (14.6), ISV (15.4), IWR (15.5), IWV ( 15.7), KFI (14.6), LIO (15.6), LOS (15.8), LTA (12.9), LEV (15.2), LTN (15.2), MAR (15) .8), MEI (14.3), MER (16.0), OBW (13.1), OFF (15.5), OSO (13.4), PAU (15.5), PHI (15. 8), RHO (14.1), SAS (15.3), SAV (14.4), TOR (15.9), TSC (12.1), UFI (15.4), UTL (15.2) ) Etc. can be mentioned. The numerical values in parentheses represent the Framework density of each structure (however, ^{the description of T / 1000A 3} is omitted).

Among these zeolites, AEI type, AFX type, BEA type, CHA type, ERI type, FAU type, LTA type, LEV type, OFF type, and RHO type are preferable in terms of versatility and solubility. It is preferably AEI type, AFX type, CHA type, ERI type, FAU type, LEV type, more preferably AFX type, CHA type, FAU type, and particularly preferably FAU type. Further, the aluminum-containing zeolite is not only an aluminum source but also a silicon source described above and a seed crystal described later.

The Si / Al molar ratio of the zeolite is not particularly limited, but is usually 1.0 or more, preferably 2.0 or more, more preferably 3.0 or more, still more preferably 4.0 or more, and particularly preferably. Is 5.0 or more, usually 50 or less, preferably 20 or less, more preferably 10 or less, still more preferably 8.0 or less, and particularly preferably 6.0 or less. By setting the Si / Al molar ratio of the zeolite in the above range, it is preferable in that the formation of zeolite having a structure other than the oxygen 8-membered ring zeolite can be suppressed.

The zeolite is not particularly limited as long as it contains aluminum, and is preferably at least one of X-type zeolite and Y-type zeolite, and more preferably Y-type zeolite.

Further, together with the above-mentioned zeolite, usually aluminum alkoxides such as aluminum sulfate, aluminum nitrate, aluminum oxide, amorphous aluminum hydroxide, crystalline aluminum hydroxide, sodium aluminate, boehmite, pseudo-boehmite, alumina sol, and aluminum isopropoxide, Aluminum-containing zeolite or the like can be used in combination.

Among these aluminum sources, in terms of reactivity, aluminum sulfate, aluminum nitrate, amorphous aluminum hydroxide and aluminum-containing zeolite are preferable, and amorphous aluminum hydroxide and aluminum-containing zeolite are more preferable. These may be used individually by 1 type and may be used in combination of 2 or more type.

(C) Alkali metal element source and / or alkaline earth metal element source The alkali metal element and alkaline earth metal element contained in the mixture used for the hydrothermal synthesis of the present embodiment are not particularly limited, and lithium, sodium, etc. Examples include potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium and the like. These may be contained alone or in combination of two or more, but are alkaline in that zeolite is likely to crystallize when a raw material having high alkalinity and low solubility is used. It preferably contains a metal element.

Examples of the alkali metal element source and the alkaline earth metal element source include hydroxides, chlorides, bromides, iodides, hydrogencarbonates, and carbonates. Of these compounds, hydroxides, bicarbonates, and carbonates are basic in an aqueous solution state. Specifically, hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, lithium hydrogencarbonate, sodium hydrogencarbonate, potassium hydrogencarbonate, Examples thereof include hydrogen carbonates such as cesium hydrogen carbonate, calcium hydrogen carbonate, strontium hydrogen carbonate and barium hydrogen carbonate, and carbonates such as lithium carbonate, sodium carbonate, potassium carbonate, cesium carbonate, calcium carbonate, strontium carbonate and barium carbonate. Of these, water is preferably an alkali metal element such as lithium hydroxide, sodium hydroxide, potassium hydroxide, and cesium hydroxide because it is highly alkaline and has the effect of promoting the dissolution of raw materials and the subsequent crystallization of zeolite. It is an oxide, more preferably lithium hydroxide, sodium hydroxide or potassium hydroxide, and even more preferably lithium hydroxide or sodium hydroxide.

As these alkali metal sources and alkaline earth metal sources, only one kind may be used, or two or more kinds may be used in combination.

(D) Quaternary ammonium salt The quaternary ammonium salt contains at least a quaternary ammonium salt composed of only independent substituents having 4 or less carbon atoms.

Specifically, tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, methyltriethylammonium, dimethyldiethylammonium, trimethylethylammonium, methyltripropylammonium, dimethyldipropylammonium, trimethylpropylammonium, methyltributylammonium, Dimethyldibutylammonium, trimethylbutylammonium, ethyltripropylammonium, diethyldipropylammonium, triethylpropylammonium, ethyltributylammonium, diethyldibutylammonium, triethylbutylammonium, propyltributylammonium, dipropyldibutylammonium, tripropylbutylammonium, etc. Be done.
By using a quaternary ammonium salt composed of only independent substituents having 4 or less carbon atoms, the hydrophobicity in the mixture can be appropriately controlled, so that the crystallization of the oxygen 8-membered ring zeolite proceeds. Easy and preferable.

It may also contain other quaternary ammonium salts. For example, it may contain a quaternary ammonium salt such as an alkyl substituted piperidinium, a trialkylbenzylammonium, a hexamethonium, or a pentaethonium cation.

The quaternary ammonium cation used as the quaternary ammonium salt is accompanied by an anion that does not inhibit the formation of the oxygen 8-membered ring zeolite of the present invention. The anion is not particularly limited, but specifically, ^{a halogen ion such as Cl −} , Br ⁻ , I ⁻ , a hydroxide ion, an acetate, a sulfate, a carboxylate or the like is used. Among them, hydroxide ion is particularly preferably used.

The quaternary ammonium salt may be used alone or in combination of two or more.

(E) Water Normally, ion-exchanged water is used.

(F) Seed crystal In the present invention, a seed crystal is added to a mixture to be subjected to hydrothermal synthesis. In the present invention, an oxygen 8-membered ring zeolite (II) is included as a seed crystal. The oxygen 8-membered ring zeolite (II) is a structural code (Framework Type Code) defined by the International Zeolite Association (IZA), and is ABW, AEI, AEN, AFN, AFT, AFX, APC, APD, ATN, ATT, ATV. , AWO, AWW, BIK, BRE, CAS, CDO, CHA, DDR, EAB, ERI, ESV, IHW, ITE, ITW, KFI, LEV, LTA, MER, MON, MTF, PAU, PHI, RHO, RTE, RTH , SAS, SAT, SAV, TSC, UFI and the like. It is preferably AEI, AFX, CHA, ERI, KFI, LEV, SAS, SAV, PAU, RHO, LTA, more preferably AFX, ERI, KFI, LEV, SAS, SAV, PAU, RHO, LTA, and further. AFX, ERI and KFI are preferable, and AFX is particularly preferable. As this seed crystal, a zeolite containing d6r in the skeleton, which is defined as a composite building unit by the International Zeolite Association (IZA), is preferable.

Only one seed crystal may be used, or a combination of seed crystals having different structures and compositions may be used. The composition of the zeolite used as the seed crystal is not particularly limited as long as it does not significantly affect the composition of the mixture.

The particle size of the zeolite used as the seed crystal is not particularly limited, but the average primary particle size is usually 0.03 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, still more preferably 0. .2 μm or more, usually 10 μm or less, preferably 5 μm or less, more preferably 2 μm or less, still more preferably 1 μm or less. By setting the average primary particle size of the seed crystal in the above range, the solubility of the seed crystal in the mixture is increased, the formation of by-products is suppressed, and the crystallization of the oxygen 8-membered ring zeolite is efficiently promoted. can do.

As the seed crystal, either a zeolite containing a structure-defining agent that has not been calcined after hydrothermal synthesis or a zeolite that has been calcined and does not contain a structure-defining agent may be used. In order to effectively act as a crystal nucleus, it is preferable not to dissolve too much in the initial stage of crystallization, so it is preferable to use a zeolite containing a structure-defining agent. However, under conditions such as low alkali concentration or low synthesis temperature, the solubility of the zeolite containing the structure-defining agent may not be sufficient. In that case, it is preferable to use the zeolite containing no structure-determining agent. ..

The seed crystal may be added to the mixture by dispersing it in a suitable solvent such as water, or it may be added directly without dispersing it.

(G) Other Metal Element Sources The mixture during hydrothermal synthesis may contain other metal element M sources. The element M source is not particularly limited, and examples thereof include boron, gallium, and iron, and preferably selected from sulfates, nitrates, hydroxides, oxides, alkoxides, element M-containing zeolites, and the like of these elements. Is used. Of these element M sources, sulfates, nitrates, hydroxides and alkoxides are preferable in terms of reactivity, and sulfates, nitrates and hydroxides are more preferable in terms of cost and work.

As the boron source, boric acid, sodium borate, boron oxide, boron-containing zeolite and the like are usually used, preferably boric acid and sodium borate, and more preferably boric acid.

As the gallium source, gallium sulfate, gallium nitrate, gallium oxide, gallium chloride, gallium phosphate, gallium hydroxide, gallium-containing zeolite or the like is usually used, preferably gallium sulfate or gallium nitrate, and more preferably. It is gallium sulfate.

As the iron source, iron nitrate, iron sulfate, iron oxide, iron chloride, iron hydroxide, iron-containing zeolite and the like are usually used, preferably iron sulfate and iron nitrate, and more preferably iron sulfate.

These elemental M sources may be used alone, in combination of two or more of the same element, or in combination of one or more of different elements. good.

The mixture may also contain sources of other metals (lead, germanium, titanium, zirconium, tin, chromium, cobalt, etc.). These may contain only one kind in the mixture, or may contain two or more kinds.

<Composition of mixture>
In the production method of the present invention, the suitable composition of the mixture (slurry or gel) to be subjected to hydrothermal synthesis is as follows. The following composition includes silicon, aluminum, element M, alkali metal element, alkaline earth metal element, quaternary ammonium salt, and water (adsorbed water) contained in the seed crystal when the seed crystal is added. It is a value calculated without.

The total molar ratio of the alkali metal atom to the alkaline earth metal atom to silicon in the mixture is usually greater than 0.010, preferably greater than 0.10, more preferably greater than 0.20, and further. It is preferably greater than 0.25, less than 0.40, preferably less than 0.37, and more preferably less than 0.34. Within the above range, alkali metal atoms and / or alkaline earth metal atoms are likely to become aluminum counter cations of oxygen 8-membered ring zeolite, and a sufficient stabilizing effect can be obtained even with a low Si / Al composition, and crystals can be obtained. Easy to change.

The molar ratio of the quaternary ammonium salt to silicon in the mixture is 0.30 or less, preferably 0.25 or less, more preferably 0.20 or less, still more preferably 0.15 or less, usually 0.010. As mentioned above, it is preferably 0.025 or more, more preferably 0.050 or more, and further preferably 0.10 or more. By setting the above ratio in the above range, the amount of the structural defining agent required for crystallization of the oxygen 8-membered ring zeolite at the time of crystallization is contained, and the crystallization proceeds efficiently, which is preferable.
The molar ratio [(quaternary ammonium salt + alkali metal + alkaline earth metal) / Si] of the total molar ratio of the quaternary ammonium salt, the alkali metal atom and the alkaline earth metal atom to the silicon atom in the mixture is particularly high. Although not limited, it is usually 0.20 or more, preferably 0.30 or more, more preferably 0.35 or more, still more preferably 0.40 or more, and usually 0.60 or less, preferably 0.50 or more. Below, it is more preferably 0.48 or less. By setting the above ratio in the above range, zeolite as an aluminum source and seed crystals are easily dissolved, and crystallization of oxygen 8-membered ring zeolite is promoted, which is preferable.

The molar ratio (Si / Al) of the silicon atom to the aluminum atom in the mixture is not particularly limited, but is usually 2.0 or more, preferably 3.0 or more, more preferably 3.5 or more, still more preferable. Is 4.0 or more, particularly preferably 4.5 or more, usually 100 or less, preferably 25 or less, more preferably 10 or less, still more preferably 8.0 or less, and particularly preferably 6.0 or less. By setting the molar ratio of silicon atom to aluminum atom in the above range, the directivity of the oxygen 8-membered ring zeolite is enhanced, the production of by-products is suppressed, and the synthesis yield is improved. Further, when used as a catalyst, it is preferable because the organic compound raw material can be efficiently converted by the acid point derived from Al.

The molar ratio (Si / M) of silicon atoms to the total of the elements M (at least one selected from the group consisting of boron, gallium, and iron) in the mixture is not particularly limited, but is usually 2. It is 5 or more, preferably 5 or more, more preferably 10 or more, and usually has no upper limit. By setting Si / M in the above range, it is incorporated into the skeleton of the oxygen 8-membered ring zeolite, and the synthesis yield is improved.

When silicon atoms in the mixture (Si) were all have become SiO _2, the molar ratio of SiO ₂ of the zeolites from for SiO ₂ is not particularly limited, usually 0.10 or more, It is preferably 0.40 or more, more preferably 0.50 or more, still more preferably 0.80 or more, usually 1.0 or less, preferably 0.95 or less, and more preferably 0.92 or less. _{By setting the molar ratio of SiO 2} derived from zeolite to the above range, the concentration of the building unit (nanoparts) derived from zeolite in the mixture becomes sufficiently high, and priority is given to the formation of the BEA phase, MFI phase, and ANA phase. Therefore, it is preferable because the crystallization of the oxygen 8-membered ring zeolite proceeds efficiently.

The total molar ratio [(alkali metal atom + alkaline earth metal atom) / Al] of the alkali metal atom and the alkaline earth metal atom to the aluminum atom in the mixture is not particularly limited, but is usually 0. It is 5.5 or more, preferably 1 or more, more preferably 2 or more, still more preferably 3 or more, and usually 15 or less, preferably 10 or less, more preferably 8 or less, still more preferably 6 or less. By setting the above ratio in the above range, the interaction between the alkali metal and the alkaline earth metal with aluminum at the time of crystallization becomes effective, and it is preferable in that an oxygen 8-membered ring zeolite can be easily obtained.

The molar ratio [(quaternary ammonium salt + alkali metal + alkaline earth metal) / Al] of the total molar ratio of the quaternary ammonium salt, the alkali metal atom and the alkaline earth metal atom to the aluminum atom in the mixture is particularly high. Although not limited, it is usually 1.0 or more, preferably 2.0 or more, more preferably 3.0 or more, and usually 15 or less, preferably 10 or less, more preferably 8.0 or less. By setting the above ratio within the above range, the interaction between aluminum and quaternary ammonium salt, alkali metal, and alkaline earth metal during crystallization becomes effective, and oxygen 8-membered ring zeolite can be easily obtained. Is preferable.

The proportion of water in the mixture is not particularly limited, the molar ratio of H _{2 O} to silicon (H 2 _{O /} Si), usually 3 or more, preferably 5 or more, more preferably 10 or more , Usually 50 or less, preferably 30 or less, more preferably 20 or less. Crystallization can be promoted by setting the proportion of water in the mixture in the above range. In addition, the productivity per reactor can be increased. It is preferable in that the stirring and mixing property can be lowered due to the increase in viscosity during the reaction and the waste liquid treatment cost can be suppressed.

The amount of seed crystals to be added in the mixture is not particularly limited, with respect to SiO ₂ when the silicon contained in the mixture other than the seed crystals to be added in the present invention (Si) is to be SiO ₂ all, usually It is 0.1% by mass or more, preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, and the upper limit is not particularly limited, but usually 50% by mass or less, preferably 30. It is 0% by mass or less, more preferably 20% by mass or less. By setting the amount of the seed crystal in the above range, the amount of the precursor directed to the oxygen 8-membered ring zeolite becomes sufficient, and crystallization can be promoted. Further, since the amount of the component derived from the seed crystal contained in the product can be suppressed and the productivity can be increased, the production cost can be reduced.

<Hydrothermal synthesis process>
By heating the above mixture in a reaction vessel (hydrothermal synthesis), an oxygen 8-membered ring zeolite can be produced.

The heating temperature (reaction temperature) is not particularly limited, and is usually 120 ° C. or higher, preferably 140 ° C. or higher, more preferably 160 ° C. or higher, usually 220 ° C. or lower, preferably 210 ° C. or lower, more preferably 200 ° C. or lower. be. By setting the reaction temperature in the above range, the crystallization time of the oxygen 8-membered ring zeolite can be shortened, and the yield of the oxygen 8-membered ring zeolite is improved. Further, it is preferable in that it can suppress the by-production of zeolites such as BEA phase and MFI phase. It is also preferable in that it can suppress the decomposition of the quaternary ammonium salt.

The time required for raising the temperature to the heating temperature (reaction temperature) is not particularly limited, and is usually 0.1 hours or more, preferably 0.5 hours or more, more preferably 1 hour or more, and the temperature rises. There is no particular upper limit to the time required for.

The heating time (reaction time) is usually 0.5 hours or more, preferably 1 hour or more, more preferably 2 hours or more, and the upper limit is usually 14 days or less, preferably 7 days or less, more preferably 3 days. It is less than or equal to, more preferably 2 days or less, and particularly preferably 1 day or less. By setting the reaction time in the above range, it is preferable that a sufficiently crystalline oxygen 8-membered ring zeolite can be obtained and the yield can be improved.

The pressure during the reaction is not particularly limited, and the spontaneous pressure generated when the mixture placed in the closed container is heated to the above temperature range is sufficient, but if necessary, an inert gas such as nitrogen may be added. good.

<Separation / purification process>
It is desirable that the oxygen 8-membered ring zeolite obtained by hydrothermal synthesis be washed with water and then the structure-defining agent contained in the oxygen 8-membered ring zeolite is removed.
The method for removing the structure-defining agent is not particularly limited, and a commonly used method known per se, such as firing or solvent extraction, may be used, but firing is desirable.

The firing temperature is usually 350 ° C. or higher, preferably 400 ° C. or higher, more preferably 450 ° C. or higher, and the upper limit is usually 900 ° C. or lower, preferably 850 ° C. or lower, more preferably 800 ° C. or lower. By setting the calcination temperature in the above range, the structure-defining agent can be efficiently removed, and the pore volume of the oxygen 8-membered ring zeolite becomes sufficiently large. In addition, it is possible to suppress the skeletal collapse and the decrease in crystallinity of the oxygen 8-membered ring zeolite.

The firing time is not particularly limited as long as the structure-defining agent is sufficiently removed, but is preferably 1 hour or more, more preferably 3 hours or more, and the upper limit is usually 24 hours or less.
The firing is preferably carried out in an atmosphere containing oxygen, and is usually carried out in an air atmosphere.

[Use of the zeolite of the present invention as a catalyst for producing a lower olefin]
<Amount of acid in catalyst>
The total acid amount and the outer surface acid amount of the catalyst can be measured by the same method as the total acid amount and the outer surface acid amount of the oxygen 8-membered ring zeolite described above. The total acid amount of the catalyst is not particularly limited, but is usually 0.010 mmol / g or more, preferably 0.10 mmol / g or more, and more preferably 0.50 mmol / g or more. Further, it is usually 2.5 mmol / g or less, preferably 2.0 mmol / g or less, and more preferably 1.5 mmol / g or less. By setting the total amount of acid in the catalyst within the above range, the catalytic activity is ensured, the formation of cork inside the pores of the zeolite is suppressed, and the formation of lower olefins can be promoted, which is preferable.

The amount of acid on the outer surface of the catalyst is not particularly limited, but is usually preferably 5% or less, more preferably 3% or less, and 0%, based on the total acid amount of the catalyst. The one is the most preferable. If the amount of outer surface acid is too large, there is a tendency for the selectivity of the lower olefin to decrease due to side reactions that occur at the outer surface acid spots.

<Other active ingredients>
The catalyst for producing a lower olefin may contain an active ingredient other than the zeolite of the present invention as long as the effect of the present invention is not impaired. Examples of other active ingredients include aluminophosphates such as silicoaluminophosphate. The content of the aluminophosphate contained in the catalyst for producing a lower olefin is usually 20% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 0% by mass. The content of zeolite contained in the catalyst of the present invention is usually 80% by mass or more, preferably 90% by mass or more, and more preferably 100% by mass. Since silicoaluminophosphate has low stability under high temperature conditions and water vapor conditions, it is preferable that the content of zeolite is high. Other active ingredients may be contained in the zeolite of the present invention in the form of mixed crystals, but usually, each active ingredient is synthesized and then mixed.

<Catalyst molding>
The above-mentioned zeolite as a catalytically active ingredient may be used as it is as a catalyst in the reaction.
A substance or binder that is inert to the reaction may be mixed to form a catalyst, which may be used in the reaction.

Examples of the substance or binder inert to the reaction include alumina or alumina sol, silica, silica sol, quartz, and a mixture thereof.

When a mixture of an oxygen 8-membered ring zeolite and a substance or binder inert to the reaction is used as a catalyst, an acid point is provided in order to adjust the total acid amount and the outer surface acid amount of the catalyst within the above ranges. It is preferable to use no silica, silica sol or the like as a binder.

When a binder having an acid point such as alumina is used, in the method for measuring the total acid amount and the outer surface acid amount of the catalyst, the total amount including the acid amount of the oxygen 8-membered ring zeolite as well as the acid amount of the binder. Measured as a value. In that case, the amount of acid derived from the binder can be obtained by another method, and the value can be subtracted from the amount of acid of the catalyst to obtain the amount of acid of zeolite alone, which does not contain the amount of acid derived from the binder. For the acid amount of the binder, the acid amount of the ^{zeolite is obtained from the peak intensity of the 4-coordinated Al derived from the acid point of the zeolite in 27} Al-NMR, and the value is obtained from the acid amount of the catalyst obtained by the ammonia heating desorption method. It is calculated by the method of deduction.

<Catalyst particle size>
The particle size of the catalyst varies depending on the synthesis conditions of the oxygen 8-membered ring zeolite and the granulation / molding conditions, but the average particle size is usually 0.01 μm to 500 μm, preferably 0.1 to 100 μm. If the particle size of the catalyst becomes too large, the effective coefficient of the catalyst tends to decrease, and if it is too small, the handleability becomes inferior. This average particle size can be obtained by SEM observation or the like.

<Methanol, dimethyl ether, ethylene, etc. as raw materials for producing lower olefins>
The origin of production of methanol and dimethyl ether, which are raw materials for producing lower olefins, is not particularly limited. For example, those obtained by the hydrogenation reaction of coal and natural gas, and CO / hydrogen mixed gas derived from by-products in the iron manufacturing industry, those obtained by the modification reaction of plant-derived alcohols, and those obtained by the fermentation method. , Recirculated plastics, those obtained from organic substances such as municipal waste, and the like. At this time, a compound in which compounds other than methanol and dimethyl ether derived from each production method are arbitrarily mixed may be used as they are, or a purified compound may be used.
As the reaction raw material, only methanol may be used, only dimethyl ether may be used, or a mixture thereof may be used. When methanol and dimethyl ether are mixed and used, there is no limitation on the mixing ratio.
Ethylene as a raw material is not particularly limited. For example, ethylene produced by catalytic cracking or steam cracking from an oil source, ethylene obtained by performing Fishertroph synthesis using a hydrogen / CO mixed gas obtained by gasification of coal as a raw material, or dehydrogenation of ethylene or ethane. Ethylene obtained by oxidative dehydrogenation, ethylene obtained by metathesis reaction and homologation reaction, ethylene obtained by MTO (Methanol to Olefin) reaction, ethylene obtained from dehydration reaction of ethanol, ethylene obtained by oxidation coupling of methane, Ethylene obtained by various other known methods can be arbitrarily used. At this time, a compound in a state in which a compound other than ethylene derived from various production methods is arbitrarily mixed may be used as it is, or purified ethylene may be used, but purified ethylene is preferable. Further, since ethanol is immediately converted to ethylene by dehydration, ethanol may be used as a raw material as it is.

As the reaction raw material, at least one selected from methanol and dimethyl ether may be mixed and used together with ethylene. When these are mixed and used, there is no limitation on the mixing ratio.

<Reactor>
The reaction mode for producing the lower olefin is not particularly limited as long as the organic compound raw material is a gas phase in the reaction region, but a fixed bed reactor, a moving bed reactor and a fluidized bed reactor are selected. Since the selectivity of lower olefins (ethylene, propylene, butene) tends to fluctuate as the conversion rate fluctuates, a fluidized bed reactor is preferable for producing these at a constant ratio.
Further, it may be carried out in any form of batch type, semi-continuous type or continuous type, but it is preferably carried out in a continuous type, and the method may be a method using a single reactor, or in series or in parallel. A method using a plurality of arranged reactors may be used.

When the fluidized bed reactor is filled with the above-mentioned catalyst, particles inactive to the reaction such as quartz sand, alumina, silica, and silica-alumina are mixed with the catalyst in order to keep the temperature distribution of the catalyst layer small. And fill it. In this case, the amount of granules that are inert to the reaction, such as quartz sand, is not particularly limited. The granular material preferably has a particle size similar to that of the catalyst from the viewpoint of uniform mixing with the catalyst.
Further, the reaction substrate (reaction raw material) may be divided and supplied to the reactor for the purpose of dispersing the heat generated by the reaction.

<Substrate concentration>
There is no particular limitation on the total concentration (substrate concentration) of the organic compound raw material in all the supply components supplied to the reactor, but usually 5 mol% or more, preferably 10 mol% or more, more preferably 20 in all the supply components. It is mol% or more, more preferably 30 mol% or more, particularly preferably 50 mol% or more, usually 95 mol% or less, preferably 90 mol% or less, and more preferably 70 mol% or less. By setting the substrate concentration in the above range, the formation of aromatic compounds and paraffins can be suppressed, and the yield of lower olefins can be improved. Further, since the reaction rate can be maintained, the amount of catalyst can be suppressed, and the size of the reactor can also be suppressed.

Therefore, it is preferable to dilute the reaction substrate with the diluents described below, if necessary, so as to obtain such a preferable substrate concentration.

<Diluent>
In the reactor, in addition to the raw materials for organic compounds, hydrocarbons such as helium, argon, nitrogen, carbon monoxide, carbon dioxide, hydrogen, water, paraffins and methane, aromatic compounds, and mixtures thereof. A gas that is inert to the reaction can be present, but it is preferable that helium, nitrogen, and water (steam) coexist among them because the separation is good.

As such a diluent, impurities contained in the reaction raw material may be used as they are, or a separately prepared diluent may be mixed with the reaction raw material and used.

Further, the diluent may be mixed with the reaction raw material before being put into the reactor, or may be supplied to the reactor separately from the reaction raw material.

<Weight Space Speed>
The weight space velocity referred to here is the flow rate of the organic compound which is the reaction raw material per weight of the catalyst (catalytically active component), and the weight of the catalyst is the inert component used for granulation and molding of the catalyst. The weight of the catalytically active ingredient without the binder. The flow rate is the total flow rate (weight / hour) of the organic compound raw materials (methanol and / or dimethyl ether and / or ethylene, etc.).

The weight space velocity is not particularly limited, but is usually 0.010 Hr ^-1 or more, preferably 0.10 Hr ^-1 or more, more preferably 0.30 Hr ^-1 or more, still more preferably 0.50 Hr ^-1 or more. It is usually 50 Hr ^-1 or less, preferably 20 Hr ^-1 or less, more preferably 10 Hr ^-1 or less, still more preferably 5.0 Hr ^-1 or less. By setting the weight space velocity in the above range, the proportion of unreacted organic compound raw materials in the reactor outlet gas can be reduced, and by-products such as aromatic compounds and paraffins can be reduced. It is preferable in that the yield of the lower olefin can be improved. Further, it is preferable because the amount of catalyst required to obtain a constant production amount can be suppressed and the size of the reactor can be suppressed.

<Reaction temperature>
The reaction temperature is not particularly limited as long as it is a temperature at which the organic compound raw material (methanol and / or dimethyl ether and / or ethylene, etc.) comes into contact with the catalyst to form a lower olefin, but is usually preferably 250 ° C. or higher. Is 275 ° C. or higher, more preferably 300 ° C. or higher, still more preferably 325 ° C. or higher, particularly preferably 350 ° C. or higher, and usually 600 ° C. or lower, preferably 550 ° C. or lower, more preferably 500 ° C. or lower, still more preferably 450 ° C. ° C. or lower, particularly preferably 400 ° C. or lower. By setting the reaction temperature within the above range, the formation of aromatic compounds and paraffins can be suppressed, so that the yield of lower olefins can be improved. In addition, since the conversion activity of the organic compound raw material can be maintained at a high level, it can be produced with a high lower olefin yield over a long period of time. Further, since dealumination from the zeolite skeleton is suppressed, it is preferable in that the catalyst life can be maintained. The reaction temperature here refers to the temperature at the outlet of the catalyst layer.

<Reaction pressure>
The reaction pressure is not particularly limited, but is usually 0.01 MPa (absolute pressure, the same applies hereinafter) or more, preferably 0.05 MPa or more, more preferably 0.1 MPa or more, still more preferably 0.2 MPa or more. It is usually 5 MPa or less, preferably 1 MPa or less, more preferably 0.7 MPa or less, still more preferably 0.5 MPa or less. By setting the reaction pressure within the above range, the formation of by-products such as aromatic compounds and paraffins can be suppressed, and the yield of lower olefins can be improved. The reaction rate can also be maintained.

<Partial pressure of raw materials>
The total partial pressure of the organic compound raw material (methanol and / or dimethyl ether and / or ethylene, etc.) is not particularly limited, but is usually 0.005 MPa or more (absolute pressure, the same applies hereinafter), preferably 0.01 MPa or more. It is more preferably 0.03 MPa or more, further preferably 0.05 MPa or more, particularly preferably 0.07 MPa or more, usually 3 MPa or less, preferably 1 MPa or less, more preferably 0.5 MPa or less, still more preferably 0.3 MPa or less. Particularly preferably, it is 0.1 MPa or less. By setting the partial pressure of the raw material within the above range, the formation of by-products such as aromatic compounds and paraffins can be suppressed, and the yield of lower olefins can be improved. The reaction rate can also be maintained.

<Conversion rate>
In the present invention, the conversion rate of methanol and / or dimethyl ether is not particularly limited, but the conversion rate is usually 90% or more, preferably 95% or more, more preferably 99% or more, still more preferably 99.5%. The above is usually 100% or less. The conversion rate of the organic compound such as ethylene is not particularly limited, but the conversion rate is usually 50% or more, preferably 60% or more, more preferably 70% or more, and usually 100%. Less than, preferably 95% or less, more preferably 90% or less. By adjusting the conversion rate so as to be within the above range, it is possible to suppress the by-product of aromatic compounds and paraffins and the accumulation of cork in the pores. In addition, the efficiency of separating unreacted raw materials from the product can be increased.

Usually, the accumulation of cork progresses with the lapse of the reaction time, and the conversion rate of the organic compound raw material tends to decrease. Therefore, the catalyst reacted for a certain period of time needs to be subjected to the regeneration treatment. The method of operating within the above conversion rate range is not particularly limited.
For example, when the reaction is carried out in a fixed bed reactor, a plurality of reactors are provided in parallel, and when the conversion rate drops from the above preferable range, the contact between the catalyst and the reaction raw material is stopped, and the reaction is stopped. The catalyst is used in the regeneration process. In the fixed bed reactor, the reaction time and the regeneration time are appropriately adjusted, that is, the time for switching between the reaction step and the regeneration step in the operation is appropriately adjusted, so that the reactor is continuously operated at the above-mentioned preferable range of conversion rate. be able to.
When the reaction is carried out in a fluidized bed reactor, a catalyst regenerator is attached to the reactor, the catalyst extracted from the reactor is continuously sent to the regenerator, and the catalyst regenerated in the regenerator is used. It is preferable to carry out the reaction while continuously returning to the reactor. By appropriately adjusting the residence time of the catalyst in the reactor and the residence time in the regenerator, continuous operation can be performed with the conversion rate in the above-mentioned preferable range.

The catalyst having a reduced conversion rate of the organic compound raw material can be regenerated by using various known catalyst regeneration methods.
The regeneration method is not particularly limited, but specifically, it can be regenerated using air, nitrogen, water vapor, hydrogen, or the like, and it is preferable to regenerate using air, hydrogen, or the like.

<Reaction product>
As the reactor outlet gas (reactor effluent), a mixed gas containing reaction products such as lower olefins such as ethylene, propylene and linear butene, by-products and diluents can be obtained. The concentration of the lower olefin in the mixed gas is not particularly limited, but is usually 5% by mass or more, preferably 10% by mass or more, and usually 95% by mass or less, preferably 90% by mass or less.
Depending on the reaction conditions, the reaction product contains unreacted raw materials, but it is preferable to carry out the reaction under reaction conditions such that the amount of unreacted raw materials is reduced. As a result, the separation of the reaction product and the unreacted raw material becomes easy, preferably unnecessary. By-products include olefins with 5 or more carbon atoms, paraffins, aromatic compounds and water. In the present invention, components other than the lower olefin may be separated and recovered, if desired. At least a part of this residue can be mixed with a part of the above-mentioned raw material gas and used as a so-called recycled gas.

The total yield of the lower olefins is not particularly limited, but is usually 50% or more, preferably 60% or more, more preferably 70% or more, still more preferably 80% or more, and the upper limit is not particularly limited. Usually 100%. When the total yield of the lower olefins is in the above range, the yield of the target product at the outlet of the reactor is sufficient, and the raw material cost and the load of separation / purification can be reduced, which is preferable.

<Separation of products>
A mixed gas containing a lower olefin (ethylene, propylene, butene) as a reaction product, an unreacted raw material, a by-product and a diluent as the reactor outlet gas was introduced into a known separation / purification facility, and each of them was introduced. Collection, purification, recycling, and discharge processing may be performed according to the components.

One embodiment of this separation / purification method includes a step of cooling / compressing the gas at the outlet of the reactor to remove most of the condensed water, and a hydrocarbon fluid containing a part of water after removing the water. Is dried with a molecular sieve or the like, and then a method including a step of purifying each olefin and paraffin by distillation is applied. In the above method, the compressed hydrocarbon fluid may be supplied to one distillation column, but a multi-stage compressor is installed to roughly separate easily condensable hydrocarbons and hard-to-condensate hydrocarbons, and separate them. It may be supplied to the distillation column of the above and distilled.

Components other than lower olefins (olefins, paraffins, etc.), especially some or all of the hydrocarbons having 5 or more carbon atoms, can be mixed with the reaction raw material after being separated and purified, or directly supplied to the reactor. You may recycle it. Further, among the by-products, the components inactive for the reaction can be reused as a diluent.

[Use of the zeolite of the present invention as an exhaust gas treatment catalyst]
When the oxygen 8-membered ring zeolite of the present invention is used as a catalyst for treating exhaust gas such as an automobile exhaust purification catalyst, the oxygen 8-membered ring zeolite of the present invention may be used as it is, and oxygen 8 containing a metal may be used as it is. A member ring zeolite may be used. Specific examples of the method for containing the metal include impregnation, liquid phase or solid phase ion exchange, and the like. Further, as described above, a metal-containing zeolite may be directly synthesized by adding a metal (either a simple substance or a compound) before hydrothermal synthesis. The presence state of the metal in the zeolite containing the metal may or may not be contained in the skeletal structure. It can also be mixed with a binder such as silica, alumina, or clay mineral, and granulated or molded before use. 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 the molded body of the catalyst for exhaust gas treatment containing the oxygen 8-membered ring zeolite of the present invention is obtained by a coating method, usually, the oxygen 8-membered ring zeolite of the present invention is mixed with an inorganic binder such as silica or alumina to prepare a slurry. It is produced by applying it to the surface of a molded body made of an inorganic substance such as cordierite and firing it, and preferably by applying it to a honeycomb-shaped molded body at this time, a honeycomb-shaped catalyst can be obtained. can. Here, an inorganic binder is used because the explanation is given by taking an exhaust gas treatment catalyst as an example, but an organic binder may be used depending on the application and usage conditions.

When the molded body of the catalyst for exhaust gas treatment containing the oxygen 8-membered ring zeolite of the present invention is obtained by molding, the oxygen 8-membered ring zeolite is usually kneaded with an inorganic binder such as silica or alumina or an inorganic fiber such as alumina fiber or glass fiber. However, it is possible to carry out molding by an extrusion method, a compression method or the like and continue firing, and preferably, by molding into a honeycomb shape at this time, a honeycomb-shaped catalyst can be obtained.

The exhaust gas treatment catalyst containing an oxygen 8-membered ring zeolite of the present invention is effective as a NOx selective reduction catalyst such as an automobile exhaust gas purification catalyst that purifies nitrogen oxides by contacting exhaust gas containing nitrogen oxides.

Further, the catalyst for treating exhaust gas, which comprises the oxygen 8-membered ring zeolite of the present invention containing a metal other than Si and Al, is also particularly effective as a selective reduction catalyst for NOx. As such a catalyst for treating exhaust gas, a transition metal is preferable as a metal element contained in zeolite, and among them, iron, cobalt, palladium, iridium, platinum, copper, silver, gold, cerium, lanthanum, placeodium, titanium, zirconium and the like. Selected from the group of. More preferably, it is selected from iron or copper. Two or more of these metals may be contained in combination. And most preferably Cu (copper). The content of the metal element other than Si and Al is usually 0.1% by weight or more, preferably 0.3% by weight or more, more than the total amount of the oxygen 8-membered ring zeolite containing the metal element other than Si and Al. It is preferably 0.5% by weight or more, particularly preferably 1.0% by weight or more, usually 20% by weight or less, preferably 10% by weight or less, and more preferably 8% by weight or less.

In particular, when the metal element contained in the zeolite is copper (Cu), the content in the catalyst is preferably 0.1% by weight or more and 10% by weight or less, and the more preferable range is as described above.

The method for incorporating the above metal into the oxygen 8-membered ring zeolite of the present invention is not particularly limited, but is generally used ion exchange method, impregnation carrying method, precipitation supporting method, solid phase ion exchange method, and CVD method. , Such as a spray drying method, preferably a method of supporting a metal on an oxygen 8-membered ring zeolite by a solid phase ion exchange method, an impregnation supporting method, or a spray drying method.

The metal raw material is not particularly limited, and usually, inorganic acid salts such as sulfates, nitrates, phosphates, chlorides and bromides of the above metals, organic acid salts such as acetates, oxalates and citrates, and penta. Organic metal compounds such as carbonyl 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, for example, 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 metal raw material, two or more kinds of different metal species or compound species may be used in combination.

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

The specific surface area of the exhaust gas treatment catalyst obtained by the present invention is not particularly limited ^{, but is preferably 300 to 1000 m 2} / g, more preferably 350 to 800 m, because the number of active sites existing on the inner surface of the pores increases. ^{It is 2} / g, more preferably 450 to 750 m ² / g. The specific surface area of the catalyst is measured by the BET method.

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, when using a catalyst, a known reducing agent such as a nitrogen-containing compound such as hydrocarbon, ammonia or urea may be used. Specifically, the exhaust gas treatment catalyst of the present invention emits various types of diesel engines, boilers, gas turbines, etc. for diesel vehicles, gasoline vehicles, stationary power generation / ships / agricultural machinery / construction machinery / motorcycles / aircraft. It can purify nitrogen oxides contained in various exhaust gases.

The oxygen 8-membered ring zeolite of the present invention is used for a catalyst for purifying nitrogen oxides, for example, in a subsequent step of purifying nitrogen oxides using the catalyst for purifying nitrogen oxides of the present invention. It can be used as an oxide catalyst for oxidizing excess reducing agents (for example, ammonia) that are not consumed in purification. As described above, the catalyst containing the oxygen 8-membered ring zeolite of the present invention can oxidize the excess reducing agent as an oxidation catalyst and reduce the reducing agent in the exhaust gas. In that case, a catalyst in which a metal such as platinum group is supported on a carrier such as zeolite for adsorbing a reducing agent can be used as an oxidation catalyst, but the oxygen 8-membered ring zeolite of the present invention may be used as the carrier. Further, the oxygen 8-membered ring zeolite of the present invention, which is used as a selective reduction catalyst for nitrogen oxides and supports, for example, iron and / or copper, can be further supported by a metal such as platinum group. ..

When using the exhaust gas treating catalyst of the present invention, it is not particularly restricted but conditions for contacting the catalyst and the exhaust gas, the space velocity of the exhaust gas is usually 100 hr ^-1 or more, preferably 1,000 hr ^-1 or more There, still more preferably 5,000 hr ^-1 or more, usually 500,000Hr ^-1 or less, preferably 400,000Hr ^-1 or less, still more preferably 200,000Hr ^-1 or less, the temperature is usually 100 ° C. or higher, It is more preferably 125 ° C. or higher, still more preferably 150 ° C. or higher, usually 1000 ° C. or lower, preferably 800 ° C. or lower, still more preferably 600 ° C. or lower, and particularly preferably 500 ° C. or lower.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

In the following preparation examples, the X-ray diffraction (XRD) pattern of the zeolite crystals obtained by synthesis was obtained using X'Pert Pro MPD manufactured by PANalytical. The X-ray source is CuKα (X-ray output: 40 kV, 30 mA) and the read width is 0.016 °. The composition of the synthesized zeolite was measured by inductively coupled plasma emission spectroscopy (ICP-AES). As for the shape of the particles, a scanning electron microscope (S-4100) manufactured by Hitachi High-Tech was used to observe the conductively treated sample at an acceleration voltage of 15 kV.

<Example 1>
Sodium hydroxide (manufactured by Kishida Chemical Co., Ltd.) 0.12 g, lithium hydroxide (manufactured by Kishida Chemical Co., Ltd.) 0.010 g, tetraethylammonium hydroxide aqueous solution (35.0% by mass, manufactured by Seichem) 0.63 g, and water 0.59 g in that order. dissolved in, H-Y-type zeolite _(SiO 2 / _Al 2 _{O 3} ratio of 10, made by Tosoh HSZ-350HUA) was added 0.65 g. Next, 0.14 g of Snowtex 40 (SiO ₂ : 40% by mass, Na2O: 0.45% by mass, manufactured by Nissan Chemical Industries, Ltd.) was added as a silica source. An additional SiO ₂ with respect to 20 wt% of AFX type zeolite _(SiO 2 / _Al 2 _{O 3} ratio of 10, an average primary particle size of about 300 nm) to give a mixture by further stirred with 0.12g as a seed crystal rice field. The mixture was placed in a 100 ml autoclave and subjected to a hydrothermal synthesis reaction at 200 ° C. for 2 hours while rotating at 15 rpm under its own pressure. The obtained product was filtered, washed with water, and dried at 100 ° C. to obtain 0.64 g of white powder (yield 79%). From the XRD pattern of the product, it was confirmed that the obtained product was in the AFX phase. From ICP elemental analysis, the Si / Al ratio was 4.4.

<Example 2>
A mixture was prepared under the same methods and conditions as in Example 1 except that 0.11 g of sodium hydroxide and 0.74 g of a tetraethylammonium hydroxyside aqueous solution were used, and the mixture was subjected to a hydrothermal synthesis reaction. Post-treatment (filtration, washing with water, drying) was carried out in the same manner as in Example 1 to obtain 0.63 g of white powder (yield 77%). From the XRD pattern of the product, it was confirmed that the obtained product was in the AFX phase.

<Example 3>
0.20 g of potassium hydroxide (manufactured by Kishida Chemical Co., Ltd.) and 0.42 g of an aqueous solution of tetraethylammonium hydroxyside (35.0% by mass, manufactured by Sechem) were dissolved in 1.5 g of water in this order, and HY-type zeolite (SiO _{2) was dissolved.} / Al ₂ O ₃ ratio 15, HSZ-360HUA manufactured by Toso Co., Ltd.) 0.68 g was added. An additional SiO ₂ relative to 10% by weight of the ERI zeolite _(SiO 2 / _Al 2 _{O 3} ratio of 10, an average primary particle size of about 500 nm) to give a mixture by further stirred with 0.060g as a seed crystal rice field. The mixture was placed in a 100 ml autoclave and subjected to a hydrothermal synthesis reaction at 160 ° C. for 2 days while rotating at 15 rpm under its own pressure. The obtained product was filtered, washed with water, and dried at 100 ° C. to obtain 0.60 g of white powder (yield 82%). From the XRD pattern of the product, it was confirmed that the obtained product was in the ERI phase. From ICP elemental analysis, the Si / Al ratio was 5.3.

<Example 4>
0.23 g of potassium hydroxide (manufactured by Kishida Chemical Co., Ltd.) and 0.37 g of dimethyldi-n-propylammonium hydroxide aqueous solution (39.8% by mass, manufactured by Seichem) were dissolved in 1.5 g of water in this order to form HY type. zeolite _(SiO 2 / _Al 2 _{O 3} ratio of 15, made by Tosoh HSZ-360HUA) was added 0.68 g. An additional SiO ₂ relative to 10% by weight of the ERI zeolite _(SiO 2 / _Al 2 _{O 3} ratio of 10, an average primary particle size of about 500 nm) to give a mixture by further stirred with 0.060g as a seed crystal rice field. The mixture was placed in a 100 ml autoclave and subjected to a hydrothermal synthesis reaction at 160 ° C. for 2 days while rotating at 15 rpm under its own pressure. The obtained product was filtered, washed with water, and dried at 100 ° C. to obtain 0.52 g of a white powder (yield 71%). From the XRD pattern of the product, it was confirmed that the obtained product was in the ERI phase.

<Example 5>
Potassium hydroxide (Kishida Chemical Co., Ltd.) 0.17 g, cesium hydroxide monohydrate (manufactured by Mitsuwa Chemical Co., Ltd.) 0.088 g, tetraethylammonium hydroxide aqueous solution (35.0 mass%, manufactured by Seichem) 0.63 g turn dissolved in water 1.4 g, H-Y-type zeolite _(SiO 2 / _Al 2 _{O 3} ratio of 15, made by Tosoh HSZ-360HUA) was added 0.68 g. An additional SiO ₂ relative to 10% by weight of the KFI-type zeolite _(SiO 2 / _Al 2 _{O 3} ratio of 10, an average primary particle size of about 1 [mu] m) to give a mixture by further stirred with 0.060g as a seed crystal rice field. The mixture was placed in a 100 ml autoclave and subjected to a hydrothermal synthesis reaction at 160 ° C. for 2 days while rotating at 15 rpm under its own pressure. The obtained product was filtered, washed with water, and dried at 100 ° C. to obtain 0.57 g of a white powder (yield 78%). From the XRD pattern of the product, it was confirmed that the obtained product was in the KFI phase. From ICP elemental analysis, the Si / Al ratio was 4.8.

<Comparative Example 1>
A mixture was prepared under the same method and conditions as in Example 1 except that 1.5 g of a tetraethylammonium hydroxyside aqueous solution was added and no water was added, and the mixture was subjected to a hydrothermal synthesis reaction. Post-treatment (filtration, washing with water, drying) was carried out in the same manner as in Example 1. From the XRD pattern of the product, the product obtained was an unknown phase and a slight AFX phase.

<Comparative Example 2>
A mixture was prepared under the same method and conditions as in Example 1 except that the amount of sodium hydroxide was 0.18 g, and the mixture was subjected to a hydrothermal synthesis reaction. Post-treatment (filtration, washing with water, drying) was carried out in the same manner as in Example 1. From the XRD pattern of the product, the product obtained was an unknown phase and a slight AFX phase.

The yields (%) and abbreviations in Table 1 above are as follows.
Yield (%) = (weight (g) of oxygen 8-membered ring zeolite containing SDA) / {(weight (g) of aluminum atomic raw material and silicon atomic raw material added at the time of production converted to _{Al 2} O ₃ and SiO _{2, respectively.} )) + (Weight (g) of seed crystal zeolite added in the present invention)} × 100
TEAOH: Tetraethylammonium Hydroxide DMDPAOH: Dimethyldi-n-Propylammonium Hydroxide

Claims (8)

The molar ratio of silicon to aluminum is 3 by hydrothermal synthesis of a mixture containing a silicon source, an aluminum source, an alkali metal element source and / or an alkaline earth metal element source, a quaternary ammonium salt, water and seed crystals. A method for producing an oxygen 8-membered ring zeolite of .0 or more and 6.0 or less .
The aluminum source contains zeolite (I) having a Framework density of 16.0 T / 1000 Å or less.
Oxygen 8-membered ring zeolite (II) is contained as the seed crystal, and the seed crystal is contained.
The quaternary ammonium salt contains a quaternary ammonium salt composed of only independent substituents having 4 or less carbon atoms.
To silicon in the mixture, the total molar ratio of the alkali metal element and the alkaline earth metal element is less than 0.40,
A method for producing an oxygen 8-membered ring zeolite, wherein the molar ratio of the quaternary ammonium salt to silicon in the mixture is 0.30 or less. A claim characterized by producing at least one oxygen 8-membered ring zeolite selected from AFX, ERI, KFI, LEV, SAS, SAV, PAU, RHO, and LTA with a code specified by the International Zeolite Association (IZA). Item 2. The method for producing an oxygen 8-membered ring zeolite according to Item 1. The oxygen according to claim 1 or 2 , wherein the total molar ratio of the alkali metal element , the alkaline earth metal element and the quaternary ammonium salt to silicon in the mixture is 0.50 or less. Method for producing 8-membered ring zeolite. The method for producing an oxygen 8-membered ring zeolite according to any one of claims 1 to 3 , wherein the molar ratio of silicon to aluminum of the zeolite (I) is 2.0 or more and 10 or less. Claims 1 to 4 are characterized in that the molar ratio _{of SiO 2} derived from the zeolite (I) to SiO ₂ when all the silicon in the mixture is SiO _{2 is 0.50 or more.} The method for producing an oxygen 8-membered ring zeolite according to any one of the above items. The oxygen 8-membered ring zeolite according to any one of claims 1 to 5 , wherein the zeolite (I) contains at least a zeolite which is a FAU under the code defined by the International Zeolite Association (IZA). Production method. A method for producing an oxygen 8-membered ring zeolite by the production method according to any one of claims 1 to 6, and using this as a catalyst for producing a lower olefin. A method for producing an oxygen 8-membered ring zeolite by the production method according to any one of claims 1 to 6, and using this as a catalyst for exhaust gas treatment.

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