JP2018154538A - Silver-containing zeolite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide novel silver-containing zeolite having high heat resistance and hydrothermal resistance, and capable of being a catalyst having improvement in coking resistance, reaction life and productivity for example in a conversion reaction or an isomerization reaction of hydrocarbon by arranging the silver-containing zeolite having no surface acid point.SOLUTION: There is provided silver-containing zeolite containing zeolite, which contains silver and has following (i) to (iv) properties, as a substrate. (i) average particle diameter (PD) is PD≤100nm. (ii) It has a 10-membered ring skeletal structure. (iii) There is no acid point on a surface. (iv) Acid amount is 0.05 o 0.85 mmol/g.SELECTED DRAWING: None

Description

  The present invention relates to a silver-containing zeolite having high heat resistance and hydrothermal resistance. More specifically, the present invention relates to a novel material having no acid sites on the surface having an average particle diameter of 100 nm or less suitable for hydrocarbon conversion / isomerization. Related to a silver-containing zeolite.

  Medium pore zeolite is used as a highly selective catalyst utilizing pores having a size corresponding to an aromatic compound. Examples of the medium pore zeolite, which is a typical MFI type zeolite, are disproportionation of toluene (for example, see Patent Document 1), isomerization of xylene (for example, see Patent Document 2), aliphatic. Examples include aromatization of hydrocarbons (see, for example, Patent Document 3). These reactions mainly utilize the micropore characteristics of medium pore zeolite. The micropore of the medium pore zeolite has an inlet diameter of about 0.5 nm and is considered to be an effective reaction field for molecules having a molecular diameter close to the pore diameter.

  On the other hand, non-selective reactions at the acid sites on the zeolite surface are generally not desirable. These non-selective reactions often result in reduced product yield, reduced product selectivity, and catalyst deactivation due to coke deposition.

  Therefore, in order to suppress an undesirable reaction on the zeolite surface, a method of reducing or eliminating the acid sites on the surface by extracting aluminum on the surface with a bulky reagent or coating the surface has been proposed.

  And the manufacture of the zeolite which reduced the acid point of the outer surface by coat | covering the zeolite which has MFI structure with a silicate, and the selective manufacturing method of p-xylene by it is proposed (for example, refer patent document 4). .)

  Moreover, the method of reducing surface acidity by coat | covering the surface acid point of a zeolite with a bulky dialkylamine reagent is proposed (for example, refer patent document 5, 6).

  Moreover, not only on the surface and inside, the acid point of zeolite decreases with time by dealumination by heating or a hydrothermal atmosphere. This phenomenon is an unavoidable problem when zeolite is used as a catalyst. The heating or hydrothermal atmosphere is due to use at a high temperature exceeding 400 ° C. or use in an environment where water vapor is generated. In particular, the latter applies to a catalyst regeneration step in which coke is burned in an atmosphere containing oxygen with respect to the catalyst after coke deposition.

  One way to suppress the dealumination of zeolite is to protect acid sites with added metals. For example, a method for improving the heat resistance and hydrothermal resistance of zeolite by containing silver in the zeolite and protecting the acid sites has been proposed (see, for example, Non-Patent Document 1).

Japanese Patent No. 40114279 Japanese Patent No. 2598127 Japanese Patent No. 2905947 Japanese Patent No. 6029654 U.S. Pat. No. 4,520,221 U.S. Pat. No. 4,568,768

Physical Chemistry Chemical Phys. Vol. 17, 15637 (2015)

  However, in the method of adding silver to the zeolite proposed in Non-Patent Document 1, although the heat resistance and hydrothermal resistance of the zeolite are improved, the coking resistance remains low due to the presence of surface acid sites, and the reaction efficiency is low. It was low.

  In addition, the surface acid point coating with amines proposed in Patent Documents 5 and 6 has a problem that amines are eliminated or decomposed at high temperatures. Further, in the method of coating the zeolite proposed in Patent Document 4 with silicate, there is a problem that the coating requires multiple hydrothermal synthesis. A relatively easy method for removing acid sites without these problems is the elimination of aluminum by water vapor. In this method, generally only the aluminum on the zeolite surface can be selectively removed. However, even the aluminum in the pores was removed, and the acid sites in the pores were lowered.

  The silver-containing zeolite of the present invention is high by selectively removing aluminum on the surface of the zeolite so that the surface has no acid sites on the surface and has acid sites only in the pores, and further contains silver. Shows heat resistance and hydrothermal resistance. Therefore, for example, in a hydrocarbon conversion reaction or isomerization reaction, it can be used as a catalyst having improved coking resistance, reaction life and productivity. The present invention can provide a silver-containing zeolite that is more useful in petrochemistry.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a novel silver-containing zeolite having no surface acid sites exhibits high heat resistance and hydrothermal resistance, and further includes hydrocarbon conversion reaction and isomerism. As a result, the present inventors have found that the catalyst can be improved in coking resistance, reaction life and productivity in the chemical reaction.

That is, the present invention relates to a silver-containing zeolite characterized by containing silver and having the following properties (i) to (iv).
(I) The average particle diameter (PD) is PD ≦ 100 nm.
(Ii) The skeleton structure is a 10-membered ring structure.
(Iii) There are no acid sites on the surface.
(Iv) The acid amount is 0.05 to 0.85 mmol / g.

  The present invention is described in detail below.

  The silver-containing zeolite of the present invention is a novel zeolite having the characteristics (i) to (iv) and containing silver. In addition, the silver content at that time is arbitrary, and it is preferably 0.05 to 5 wt% because a silver-containing zeolite having particularly excellent heat resistance and hot water resistance is obtained.

  The silver-containing zeolite of the present invention is (i) PD ≦ 100 nm. In particular, since it becomes a silver-containing zeolite having excellent thermal stability, it is desirable that 3 nm ≦ PD ≦ 100 nm, and further desirably 5 nm ≦ PD ≦ 100 nm. Here, when the PD exceeds 100 nm, the obtained silver-containing zeolite is inferior in reaction efficiency when used in a hydrocarbon conversion reaction / isomerization reaction.

In addition, PD can be calculated | required, for example using the following formula | equation (1) from the outer surface area of a zeolite.
PD = 6 / S (1 / 2.29 × 10 ⁶ + 0.18 × 10 ⁻⁶ ) (1)
(Here, S represents the outer surface area (m ² / g).)
Further, the outer surface area (S (m ² / g)) in the formula (1) can be obtained from the t-plot method using a general nitrogen adsorption method at a liquid nitrogen temperature. For example, when t is the thickness of the adsorption amount, a measurement point in the range of 0.6 to 1 nm is linearly approximated with respect to t, and the outer surface area of zeolite is obtained from the slope of the obtained regression line.

  The silver-containing zeolite is (ii) a skeleton having a 10-membered ring structure. Examples of the zeolite having a 10-membered skeleton structure include zeolites such as AEL, EUO, FER, HEU, MEU, MEL, MFI, and NES types, and are particularly suitable for hydrocarbon conversion and isomerization reactions. Therefore, MFI, FER, and MEL type zeolite are preferable, and MFI type zeolite is particularly preferable.

  The silver-containing zeolite (iii) has no acid sites on the surface.

  Here, the surface acid point of the zeolite indicates the acid point existing on the surface of the zeolite as the term implies. Normally, zeolite has acid sites on its surface and (micro) pores, and having no acid sites on the surface can be said to have acid sites only in (micro) pores. It is. And since it becomes a base which is excellent in especially heat resistance, hot water resistance, and durability, it is preferable that it is a silver containing zeolite which has the surface which is not coat | covered with the silicate, the dialkylamine reagent, etc.

  As a method for confirming the acid point on the surface of the zeolite (the acid point does not exist on the surface), any method can be used as long as the confirmation is possible. (Characterization of acid sites on the external surface of zeolites, Reaction Kinetics and Catalysis Letters, vol. 67, p. 281) (p. 281). 2,4-Dimethylquinoline has acid sites (—OH) existing on the zeolite surface (including the pore inner surface) and adsorption properties, but the (micro) pore diameter of the zeolite is 2,4-dimethyl. If it is smaller than the quinoline molecule, it cannot penetrate into the (micro) pores and cannot adsorb to the acid sites in the (micro) pores. That is, it adsorbs only on the acid sites on the zeolite surface. Therefore, when adsorption of 2,4-dimethylquinoline to the acid sites (—OH) present on the zeolite surface is not observed, it can be determined that there are no acid sites on the zeolite surface.

As a more specific method, an infrared absorption spectrum measurement at 150 ° C. of zeolite that has been degassed and dehydrated at 400 ° C. for 2 hours as a pretreatment of zeolite is performed. Then, 2,4-dimethylquinoline gas is introduced into the deaerated and dehydrated zeolite and adsorbed for 10 minutes, and the excess 2,4-dimethylquinoline is removed by exhausting at 150 ° C., and 2,4-dimethylquinoline is removed. An adsorption zeolite is prepared and an infrared absorption spectrum is measured at 150 ° C. That is, in the difference spectrum of infrared absorption before and after adsorption of 2,4-dimethylquinoline, when no difference (decrease) in infrared absorption can be confirmed in the range of 3600 to 3650 cm ⁻¹ , it is determined that there are no acid sites on the surface. Can do. 2,4-Dimethylquinoline is also adsorbed on silanol sites on the zeolite surface, but absorption derived from silanol OH stretching vibration is observed at 3700-3800 cm ⁻¹ . On the other hand, the absorption derived from the OH stretching vibration of the acid point on the zeolite surface is observed at 3600 to 3650 cm ^−1, and the absorption derived from the OH stretching vibration of the acid point by adsorbing 2,4-dimethylquinoline. A decrease in the infrared absorption spectrum in the range of 3600 to 3650 cm ⁻¹ indicates that 2,4-dimethylquinoline was adsorbed on the surface acid sites of the zeolite.

  The silver-containing zeolite has (iv) an acid amount of 0.05 to 0.85 mmol / g, preferably 0.05 to 0.55 mmol / g. Here, in the case of a zeolite having an acid amount exceeding 0.85 mmol / g, coke adheres easily when used in a hydrocarbon conversion / isomerization reaction, and the conversion / isomerization reaction is rapidly deactivated. When the zeolite has an acid amount of less than 0.05 mmol / g, the activity during the conversion / isomerization reaction of the hydrocarbon is low. The acid amount in the silver-containing zeolite is (iii) that has no acid point on the surface, and is basically the acid amount of the acid point in the (micro) pore. is there.

  The acid amount can be measured using a method generally known as an acid amount measuring method. For example, the ammonia-TPD method (solid acid property measurement by ammonia temperature-programmed desorption method, catalyst) , Vol.42, p.218 (2000)). Specifically, ammonia is saturatedly adsorbed on zeolite at room temperature, heated to 100 ° C. to remove ammonia remaining in the measurement atmosphere, and then heated up to 700 ° C. at a heating rate of 10 ° C./min. Among the ammonia peaks measured in (1), the amount of ammonia desorbed on the high temperature side showing a strong acid point can be used as the solid acid amount.

Further, the silver-containing zeolite of the present invention may be any as long as the SiO ₂ / Al ₂ O ₃ ratio belongs to the category called zeolite, and in particular, in hot water resistance and durability. Since it is excellent, it is preferable that the SiO ₂ / Al ₂ O ₃ ratio is 20 to 300, particularly excellent in heat resistance, reaction selectivity and productivity when used in hydrocarbon conversion / isomerization reaction. since the _things, it is preferable that SiO 2 / _Al 2 _{O 3} ratio = 30 to 200.

The silver-containing zeolite can be based on a zeolite having the following characteristics (v) to (viii) and contain silver. Examples of the production method in this case include the following (v) There can be mentioned a method of introducing silver into a zeolite having the characteristics of (viii) by a method such as impregnation support, ion exchange, and skeleton substitution.
(V) PD ≦ 100 nm.
(Vi) The skeleton structure is a 10-membered ring structure.
(Vii) There are no acid sites on the surface.
(Viii) Acid amount is 0.1-1.0 mmol / g.

  At that time, the base zeolite is (v) PD ≦ 100 nm. In particular, since it becomes a silver-containing zeolite having excellent thermal stability, it is desirable that 3 nm ≦ PD ≦ 100 nm, and further desirably 5 nm ≦ PD ≦ 100 nm. The PD can be obtained by calculation using the above method, that is, the above equation (1).

  The base zeolite is (vi) a skeleton structure having a 10-membered ring structure. Examples of the zeolite having a 10-membered skeleton structure include zeolites such as AEL, EUO, FER, HEU, MEU, MEL, MFI, and NES types, and are particularly suitable for hydrocarbon conversion and isomerization reactions. Therefore, MFI, FER, and MEL type zeolite are preferable, and MFI type zeolite is particularly preferable.

  The base zeolite is (vii) one having no acid sites on the surface. And the above-mentioned method can be mentioned as confirmation of the acid point on the surface of a zeolite (no acid point exists on the surface).

  The base zeolite has (viii) an acid amount of 0.1 to 1.0 mmol / g, preferably 0.1 to 0.6 mmol / g. Note that the acid amount in the base zeolite is (vii) that has no acid sites on the surface, and is basically the acid amount of the acid sites in the (micro) pores. It is. The acid amount can be measured by the above-described method.

  As a method for producing a zeolite as a base material, any method can be used as long as it is possible to produce a zeolite that satisfies the characteristics described in (v) to (viii) above. And, as a method for selectively removing the acid sites on the surface of the zeolite having no acid sites on the surface, that is, as a method for selectively removing the acid sites on the surface of the zeolite, calcination (heat treatment) when producing zeolites satisfying the characteristics (v) to (vi) A method in which a part or all of the process is a hydrothermal (steam) treatment process and an ion exchange process is added before and after the baking process can be mentioned.

  As a method for synthesizing zeolite satisfying the characteristics (v) to (vi), a generally known method is used to obtain a zeolite having PD ≦ 100 nm and having a 10-membered ring skeleton structure. Specifically, it can be produced by mixing a compound containing an alkali metal and / or alkaline earth metal as a cation, an organic structure directing agent and an aluminosilicate gel, and firing the obtained crystal. . Examples of the compound containing an alkali metal or an alkaline earth metal at that time include sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, and the like. Among these, sodium hydroxide is preferable. Examples of the organic structure directing agent include tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and tetraethylammonium hydroxide. Moreover, as an aluminosilicate gel, an amorphous aluminosilicate gel can be mentioned, for example.

  Furthermore, when making the zeolite satisfying the characteristics of (v) to (viii), ion exchange is performed before firing the crystalline material obtained as described above, and part or all of the firing is hydrothermally treated. Then, it becomes possible to manufacture by a method of further ion exchange.

  As baking conditions in that case, 300-900 degreeC is preferable as processing temperature, and it is especially preferable that it is 400-700 degreeC. The treatment time is preferably 10 minutes to 40 hours industrially. As the atmosphere, for example, one or a combination of two or more of nitrogen, air, oxygen, argon, and other inert gases can be used. And the aluminum of a proton acid point is desorbed by performing a hydrothermal (steam) process for a part or all of this baking process. The treatment temperature for the hydrothermal treatment is preferably 400 to 750 ° C, particularly preferably 500 to 650 ° C. Further, the water vapor concentration is preferably 10 to 100%, and particularly preferably 40 to 90%.

  In addition, the ion exchange is performed before and after the firing step, and may be divided into a plurality of ion exchanges. Examples of the ion exchange include ion exchange using an acid such as ammonium chloride, hydrochloric acid, and nitric acid, and those using hydrochloric acid and nitric acid are preferable. Also, ion exchange can be substituted by washing with water.

  The silver-containing zeolite of the present invention has high heat resistance and hydrothermal resistance in order to suppress dealumination of the zeolite by high temperature and steam. Further, the surface does not have an acid point. Therefore, for example, when used in a hydrocarbon conversion reaction or isomerization reaction, it has high coking resistance, reaction lifetime and productivity. For example, an aromatic compound can be efficiently produced by contacting with an aliphatic hydrocarbon, particularly an aliphatic hydrocarbon having 10 or less carbon atoms, or an aliphatic hydrocarbon having 2 to 6 carbon atoms. is there. Examples of the aliphatic hydrocarbon at that time include paraffinic, olefinic, acetylenic, and alicyclic hydrocarbons, such as ethane, propane, butane, isobutane, pentane, Examples thereof include paraffins such as hexane; olefins such as ethylene, propylene, butene, isobutene, pentene, and hexene; acetylenes such as acetylene; alicyclic systems such as cyclopropane, cyclobutane, and cyclohexane, and mixtures thereof.

  The present invention relates to a novel silver-containing zeolite having fine pores in microcrystals from which surface acid sites have been removed and containing silver, and has high heat resistance and hydrothermal resistance. Therefore, when used as a catalyst for conversion / isomerization of hydrocarbons, high coking resistance, long life, high productivity, and regeneration efficiency can be expected.

  EXAMPLES Specific examples of the present invention will be described below as examples, but the present invention is not limited to these examples.

-Measurement of external surface area of zeolite-
The outer surface area of the zeolite was measured by nitrogen adsorption measurement.

  As the nitrogen adsorption measurement, a nitrogen adsorption apparatus ((trade name) Belsorb-max, manufactured by Microtrack Bell) was used, and both adsorption and desorption were measured under the condition of 40 torr / step. The outer surface area was obtained by linearly approximating the range of the adsorption layer thickness (t = 0.6 to 1.0 nm) by the t-plot method.

~ Measurement of average particle diameter ~
The average particle size was calculated from the outer surface area of the zeolite using the above formula (1). In formula (1), S is an external surface area (m ² / g), and PD is an average particle diameter (m).

~ Measurement of SiO ₂ / Al ₂ O ₃ ratio, metal content ~
The SiO ₂ / Al ₂ O ₃ molar ratio of the zeolite and the metal content were determined by dissolving the zeolite in a mixed aqueous solution of hydrofluoric acid and nitric acid, and using a general ICP apparatus ((trade name) OPTIMA3300DV, manufactured by PerkinElmer). It was determined by inductively coupled plasma emission spectroscopy (ICP-AES).

~ 2,4-Dimethylquinoline adsorption infrared absorption spectroscopy ~
Infrared absorption spectroscopy is performed using a general FT-IR measurement device ((trade name) Varian 660-IR, manufactured by Agilent Technologies) with components for IR measurement devices under vacuum ((trade name) multi-mode cell). , Manufactured by ST Japan Co., Ltd.). The sample was molded into a disk, placed in a cell, heated to 400 ° C. at 10 ° C./min under vacuum evacuation, and held for 2 hours. After cooling to 150 ° C., an infrared absorption spectrum before 2,4-dimethylquinoline adsorption was measured. 2,4-dimethylquinoline gas was introduced, adsorbed for 10 minutes, evacuated at 150 ° C. for 1 hour, and the infrared absorption spectrum after adsorption of 2,4-dimethylquinoline was measured. The difference between the infrared absorption spectrum after adsorption of 2,4-dimethylquinoline and the spectrum before adsorption was taken, and the change in infrared absorption due to adsorption was measured.

-Measurement method of acid amount-
The acid amount was measured using a general NH ₃ -TPD apparatus ((trade name) BELCATII, manufactured by Microtrack Bell Co., Ltd.) and a gas analyzer ((trade name) BEL Mass, manufactured by Microtrack Bell Co., Ltd.). . The sample was granulated, placed in a cell, heated to 500 ° C. at 10 ° C./min in a helium atmosphere, and held for 1 hour. Thereafter, the temperature was lowered to 100 ° C., and 0.2% ammonia gas was introduced for 30 minutes. The temperature was raised to 600 ° C. at 10 ° C./min, and the desorbed ammonia was analyzed with a gas analyzer. The acid amount of the sample was calculated from the remaining desorption amount excluding the desorption amount derived from the weak acid.

-Aromatic compound production apparatus and production method thereof-
As the reaction apparatus, a fixed bed gas phase flow reaction apparatus using a stainless steel reaction tube (inner diameter: 16 mm, length: 300 mm) was used. The middle stage of each of the stainless steel reaction tubes was filled with an aromatic compound production catalyst, pre-heated under a flow of dry air, and then fed with a raw material gas. The reactor apparatus conditions and operating conditions are not limited to those described in this example, and can be selected as appropriate. The heating was performed using a ceramic tubular furnace, and the temperature of the catalyst layer (reaction field) was controlled. The reaction outlet gas and the reaction liquid were collected, and the gas component and the liquid component were individually analyzed using a gas chromatograph. The gas component was analyzed using a gas chromatograph (manufactured by Shimadzu Corporation, (trade name) GC-1700) equipped with a TCD detector. As the filler, PorapakQ (trade name) manufactured by Waters or MS-5A (trade name) manufactured by GL Science was used. The liquid component was analyzed using a gas chromatograph (manufactured by Shimadzu Corporation, (trade name) GC-2015) equipped with an FID detector. A capillary column (manufactured by GL Sciences, (trade name) TC-1) was used as the separation column.

  The reaction conditions were set as follows.

(Aromatic compound production conditions)
Catalyst layer temperature: 575 ° C.
Flowing gas: 1-butene 50 mol% + nitrogen 50 mol% mixed gas, 80 ml / min.
Regeneration temperature: 520 ° C.
Regenerative gas: air, 50 ml / min.
Ratio of volume of feed hydrocarbon to catalyst volume: 1000 / hour.
Catalyst weight: 0.9 g.
Catalyst shape: Metal-containing zeolite powder was molded at 400 kgf / cm ² for 1 minute and then pulverized into a pellet shape of about 1 mm.
Reaction pressure: 0.1 MPa.

Preparation Example 1
Amorphous aluminosilicate gel was added and suspended in an aqueous solution of tetrapropylammonium (hereinafter sometimes abbreviated as TPA) hydroxide and sodium hydroxide. MFI-type zeolite was added as seed crystals to the resulting suspension to obtain a raw material composition. The amount of seed crystals added at that time was 0.7% by weight with respect to the weight of Al ₂ O ₃ and SiO _{2 in} the raw material composition. By-produced ethanol was removed by evaporation.

The composition of the raw material composition is as follows.
SiO ₂ / Al ₂ O ₃ molar ratio = 48, TPA / Si molar ratio = 0.05, Na / Si molar ratio = 0.16, OH / Si molar ratio = 0.21, H ₂ O / Si molar ratio = 10
The obtained raw material composition was sealed in a stainless steel autoclave and crystallized with stirring at 115 ° C. for 4 days to obtain a slurry mixture. The slurry-like mixed liquid after crystallization was subjected to solid-liquid separation with a centrifugal settling machine, and then the solid particles were washed with a sufficient amount of pure water and dried at 110 ° C. to obtain a dry powder.

  The obtained dry powder was dispersed in 1 mol / L hydrochloric acid, filtered and dried. After calcination at 550 ° C. for 1 hour in air, the mixture was treated with 600 ° C. and 80% water vapor for 2 hours.

  The obtained powder was dispersed in 1 mol / L hydrochloric acid, filtered and dried to obtain MFI type zeolite.

The obtained MFI-type zeolite had a 10-membered ring skeleton structure, an average particle diameter of 40 nm, a SiO ₂ / Al ₂ O ₃ molar ratio of 68, and an acid amount of 0.23 mmol / g.

FIG. 1 shows a difference spectrum of infrared absorption before and after 2,4-dimethylquinoline is adsorbed on the obtained MFI type zeolite. Peak derived from OH zeolite acid sites of 3605cm ^-1 is not reduced, the peak derived from OH of silanol 3700～3800Cm ^-1 decreased significantly. Therefore, it was confirmed that 2,4-dimethylquinoline was adsorbed only on silanols on the zeolite surface and no acid sites were present on the zeolite surface.

Example 1
The MFI zeolite obtained in Preparation Example 1 was supported with silver by an ion exchange method. 1.23 g (2.49 mmol) of silver nitrate was dissolved in 300 ml of distilled water, 3 g of MFI zeolite obtained in Preparation Example 1 was added to 100 ml of the aqueous solution to form a slurry solution, and the mixture was stirred in a 45 ° C. water bath for 2 hours. After filtering with a Buchner funnel, 100 ml of an aqueous silver nitrate solution was added again, followed by stirring in the same manner. After repeating three times, the filtered zeolite was dried at 110 ° C. overnight and calcined at 550 ° C. for 4 hours.

The silver content of the obtained silver-containing MFI zeolite was 1.6 wt%. It had a 10-membered ring skeleton structure, an average particle size of 40 nm, a SiO ₂ / Al ₂ O ₃ molar ratio of 68, no acid sites on the surface, and an acid amount of 0.20 mmol / g.

  The zeolite was used as an aromatic production catalyst and 1-butene was used as a raw material to carry out an aromatization reaction according to the above. The reaction results are shown in Table 1. The aromatic yield was 44.7 wt% in 75 minutes and 39.3 wt% in 900 minutes. Further, regeneration was performed under the above conditions, and an aromatization reaction was again performed using 1-butene as a raw material. The reaction results are shown in Table 2. The aromatic yield with respect to the distribution time was the same before and after the regeneration. It was confirmed that it has high heat resistance and hydrothermal resistance by suppressing the yield reduction even under severe regeneration conditions.

Comparative Example 1
The MFI-type zeolite obtained in Preparation Example 1 was used as an aromatic production catalyst, and 1-butene was used as a raw material to carry out an aromatization reaction according to the above. The results are shown in Table 3. The aromatic yield was 40.4 wt% in 75 minutes and 33.0 wt% in 900 minutes. The aromatic yield (catalytic performance) decreased in a short time. Further, regeneration was performed under the above conditions, and an aromatization reaction was again performed using 1-butene as a raw material. The reaction results are shown in Table 4. After the regeneration, the aromatic yield decreased particularly from 480 minutes compared with before the regeneration. It was confirmed that dealumination progressed under severe regeneration conditions and was inferior in heat resistance and hot water resistance.

Preparation Example 2
Zeolite crystallization by autoclave, washing and drying were performed in the same manner as in Preparation Example 1.

  The obtained dry powder was calcined at 550 ° C. in the air, and then the obtained powder was dispersed in 1 mol / L hydrochloric acid, filtered and dried to obtain zeolite.

The obtained zeolite had a 10-membered ring skeleton structure, an average particle diameter of 41 nm, a SiO ₂ / Al ₂ O ₃ molar ratio of 46, and an acid amount of 0.22 mmol / g.

FIG. 1 shows a difference spectrum of infrared absorption before and after 2,4-dimethylquinoline was adsorbed on the obtained zeolite. A peak derived from OH zeolite acid sites of 3605cm ^-1, a peak derived from OH of silanol 3700～3800Cm ^-1 decreased. Therefore, it was confirmed that 2,4-dimethylquinoline was adsorbed on acid sites and silanols on the zeolite surface, and acid sites were present on the zeolite surface.

Comparative Example 2
The MFI-type zeolite obtained in Preparation Example 2 was supported with silver in the same manner as in Example 1. The resulting zeolite had a silver content of 1.4 wt%. It had a 10-membered ring skeleton structure, the average particle diameter was 41 nm, the SiO ₂ / Al ₂ O ₃ molar ratio was 46, acid points were present on the surface, and the acid amount was 0.19 mmol / g. The zeolite was used as an aromatic production catalyst and 1-butene was used as a raw material to carry out an aromatization reaction according to the above. The reaction results are shown in Table 5. The aromatic yield was 47.0 wt% in 75 minutes and 24.9 wt% in 300 minutes. The aromatic yield (catalyst performance) decreased significantly in a short time. Further, regeneration was performed under the above conditions, and an aromatization reaction was again performed using 1-butene as a raw material. The reaction results are shown in Table 6. After regeneration, the initial conversion rate and aromatic yield decreased compared to before regeneration. Moreover, it decreased notably with the increase in distribution time, and it confirmed that it was inferior to heat resistance, hot water resistance, and durability.

  The present invention relates to a metal-containing zeolite having high heat resistance and hydrothermal resistance. In addition, the metal-containing zeolite is high when used as a catalyst for hydrocarbon conversion or isomerization because there are no acid sites on the surface having an average particle size of 100 nm or less suitable for hydrocarbon conversion / isomerization. It exhibits coking resistance, life, productivity, etc. Therefore, industrial value is extremely high.

FIG. 3 is a diagram showing infrared absorption spectra of zeolites obtained in Preparation Example 1 and Preparation Example 2 (before and after adsorption of 2,4-dimethylquinoline).

Claims (5)

A silver-containing zeolite containing silver and having the following properties (i) to (iv):
(I) The average particle diameter (PD) is PD ≦ 100 nm.
(Ii) The skeleton structure is a 10-membered ring structure.
(Iii) There are no acid sites on the surface.
(Iv) The acid amount is 0.05 to 0.85 mmol / g. The silver-containing zeolite according to claim 1, wherein the silver-containing zeolite contains 0.05 to 5 wt% of silver. Silver-containing zeolite according to claim 1 or ₂ SiO 2 / _Al 2 _{O 3} ratio is characterized in that it is 20 to 300. The silver-containing zeolite according to any one of claims 1 to 3, wherein the silver-containing zeolite is selected from the group consisting of MFI type zeolite, MEL type zeolite and FER type zeolite. A silver-containing zeolite comprising a zeolite having the following characteristics (v) to (viii) as a base material and containing silver.
(V) PD ≦ 100 nm.
(Vi) The skeleton structure is a 10-membered ring structure.
(Vii) There are no acid sites on the surface.
(Viii) Acid amount is 0.1-1.0 mmol / g.

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