JP2020081991A - Method for regenerating metal ion-carrying zeolite catalyst - Google Patents

Abstract

To provide a method for regenerating catalysts as a metal ion-carrying zeolite catalyst, by reconstructing metal clusters and metal particles, which are aggregated metal ions by use as a catalyst, into original metal ions and redispersing the metal ions onto acid points of the zeolite.SOLUTION: There is provided a method for regenerating a metal ion-carrying zeolite catalyst in which a used metal ion-carrying zeolite catalyst is in contact with a gas having an oxygen content of 4 to 25% at the temperature of 480 to 650°C.SELECTED DRAWING: None

Description

The present invention relates to a method for regenerating a metal ion-supported zeolite catalyst, and in particular, the use of the catalyst as a catalyst restores metal clusters or metal particles in which metal ions are aggregated to the original metal ions and re-converts them into acid points of zeolite. The present invention relates to a method for regenerating a dispersed metal ion-supported zeolite catalyst.

Zeolite catalysts are used in various fields as catalysts, carriers, adsorbents and the like. And, as the catalyst, it has been developed in the fields of organic synthesis catalyst, exhaust gas catalyst, hydrocarbon decomposition, isomerization reaction, aromatization reaction, hydrocracking reaction, alkylation reaction, synthesis gas conversion reaction, and the like. ..

The first problem with these zeolite catalysts is so-called coking, in which carbonaceous materials accumulate on the zeolite catalyst during the reaction and the activity decreases. In order to recover the activity decrease due to this coking, industrially, a regeneration process for burning and removing carbonaceous substances is incorporated, and the actual operation is continued by alternately repeating the reaction and regeneration. Therefore, although the activity decrease due to coking apparently decreases, the activity reversibly returns upon regeneration, so the catalyst performance does not deteriorate. The countermeasure against coking is to suppress the accumulation of carbonaceous substances, to make the reaction time as long as possible, to shorten the regeneration time, or to reduce the number of regenerations within a certain period.

The second problem is that, when the coke accumulated in the zeolite catalyst whose activity has been reduced due to use or coking is burned and removed, the aluminum in the zeolite lattice is desorbed due to the presence of moisture generated in a high temperature atmosphere, which causes a decrease in activity. .. This is a permanent decrease in active sites, and since it progresses irreversibly, the activity does not return to the original state as in the above-mentioned coking, which is so-called catalyst deterioration.

A method of adding metal ions is known as a method of preventing catalyst deterioration due to dealumination. For example, in Patent Document 1, in order to improve the hydrothermal stability of a zeolite catalyst, a catalyst obtained by introducing a monovalent monoatomic Group 1B cation, preferably silver into the zeolite is used in the zeolite and the subsequent regeneration is performed. It is disclosed that the duration of the hydrocarbon conversion reaction during the period does not exceed 6 months.

Further, Patent Document 2 proposes a high-silica zeolite-based catalyst which is excellent in regeneration deterioration resistance and coking resistance. According to Patent Document 2, the particle diameter of primary particles is 0.3 to 3 μm, the molar ratio of silica/alumina is 20 to 200, and the ratio of surface acid points to total acid points when the zeolite-based catalyst is H type is 0. High silica zeolite in which the amount of pyridine desorbed at 500 to 900° C. by the temperature programmed desorption method after steaming at 0.03 to 0.15 and steam partial pressure of 0.8 atm at 650° C. for 5 hours is within a certain range. By using a system-based catalyst, the amount of carbonaceous material that accumulates on the catalyst during the reaction is reduced, and the catalyst is dealuminated by dealumination in a high-temperature atmosphere containing water, which occurs when burning and removing with an oxygen-containing inert gas. It is described that deterioration can be suppressed.

Patent Document 3 proposes a zeolite-containing molded catalyst which suppresses activity reduction due to coking and catalyst deterioration during regeneration. According to Patent Document 3, a primary particle diameter is 0.02 to 0.25 μm, a silver is contained in a cation state, and a zeolite containing an intermediate pore diameter zeolite having a pore diameter of 5 to 6.5 angstroms containing elemental zinc is contained. It is described that the use of the molded catalyst makes it possible to suppress the activity decrease due to coking and the catalyst deterioration at the time of regeneration by a simpler method than the conventional technique.

Further, as a method for stabilizing metal cations, Patent Document 4 discloses that a reducing chemical conversion atmosphere is kept for a period shorter than the period required to generate metal clusters to restore and maintain the distribution of metal cation sites in the catalyst. It has been proposed to regenerate the catalyst in an oxidizing atmosphere under these conditions. Metal cations are reduced to a single atomic state whose valence is not more than zero in a reducing chemical conversion atmosphere, but the metal also acts as a catalyst to aggregate on the surface and grow into metal clusters and larger metal particles. If it is kept in a reducing atmosphere enough to protect it, it becomes difficult to restore it to the metal cation state by subsequent exposure to an oxidizing atmosphere. When metal clusters and metal particles are generated, protonic acid points are generated as much as the metal cations are removed. This protic acid point is lower in hydrothermal stability than the acid point where a metal cation is present, so dealumination cannot be suppressed.

Therefore, it exists in one atomic state whose valence is not more than zero, and it is possible to switch from the reducing chemical conversion atmosphere to the oxidizing atmosphere within a period in which the metal cations can be reversibly restored by exposure to the oxidizing atmosphere. The activity can be maintained. According to Patent Document 4, the reaction time is described as a period of 1 second or more seconds, or less than 1 second.

JP-A-59-117584 JP, 10-52646, A Patent 5179882 Japanese Patent Publication No. 62-4175

However, the proposal of Patent Document 1 is to introduce metal ions for improving hydrothermal stability, but it is known that the introduced metal aggregates in a reducing atmosphere to form metal clusters or metal particles. ing. The method of Patent Document 2 uses a zeolite having a specific property to reduce the amount of carbonaceous matter accumulated on the catalyst during the reaction, and the presence of water as occurs when burning and removing with an oxygen-containing inert gas. The present invention provides a zeolite catalyst for suppressing catalyst deterioration due to dealumination in a high temperature atmosphere. Patent Document 3 proposes a zeolite-containing molded body catalyst that suppresses activity reduction due to coking and catalyst deterioration during regeneration. However, none of Patent Documents 1 to 3 proposes a method of restoring metal clusters or metal particles used or aggregated in a reducing atmosphere to the original metal ions and redispersing them to acid sites.

The proposal of Patent Document 4 is a method of terminating the reaction and converting the metal cations into metal clusters or metal particles before the regeneration, but the reaction time is a period of one second or more. It is short or less than 1 second, which is not practical, and merely discloses a method of maintaining the dispersibility of the metal to maintain the acid sites, and it is possible to obtain clusters of metal particles or metal particles. After that, no method has been proposed to restore the cations and redisperse them to the acid sites.

As described above, the regeneration proposed in Patent Documents 1 to 4 is aimed at burning and removing the accumulated coke, and the metal clusters and metal particles aggregated by the reaction are restored to the original metal ions to form the zeolite. The conditions for redispersion to acid sites have not been considered at all. Then, in the zeolite catalyst whose activity has been lowered by coking, metal clusters and metal particles aggregated by the normal reaction are generated. Therefore, the metal ions disappear by the amount of the aggregated metal clusters and metal particles, and protonic acid points are produced. This protic acid point is lower in hydrothermal stability than the acid point where a metal cation is present, so dealumination cannot be suppressed.

Therefore, by using metal ion-supported zeolite as a catalyst, metal clusters and metal particles that have been aggregated are restored to the original metal ions and redispersed at the acid points of the zeolite to suppress dealumination and suppress metal deterioration. There is a need for a method of regenerating an ion-supported zeolite catalyst.

As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention treated the metal ion-supporting zeolite whose performance was deteriorated by use as a catalyst under specific conditions, and thus the metal agglomerated by the reaction. The inventors have found that it is possible to regenerate the metal ion-supporting zeolite as a catalyst by restoring the clusters and metal particles to the original metal ions and redispersing them to the acid sites, and completed the present invention.

That is, the present invention relates to a method for regenerating a metal ion-supported zeolite catalyst, which comprises contacting a used metal ion-supported zeolite catalyst with a gas having an oxygen content of 4 to 25% and 480 to 650°C. ..

The present invention will be described in detail below.

The method for regenerating a metal ion-supported zeolite catalyst of the present invention is a metal ion support for restoring metal clusters or metal particles, in which metal ions are aggregated by use for a certain period of time as a catalyst, to the original metal ions and redispersing them to acid sites. The present invention relates to regeneration of a zeolite catalyst, in which a metal ion-supported zeolite catalyst is regenerated by contacting with a gas having an oxygen content of 4 to 25% and a temperature of 480 to 650° C. to redisperse the metal ion.

(Metal ion supported zeolite catalyst)
The metal ion-supported zeolite catalyst in the present invention includes organic synthesis catalyst, exhaust gas catalyst, hydrocarbon decomposition catalyst, isomerization reaction catalyst, aromatization reaction catalyst, hydrocracking reaction catalyst, alkylation reaction catalyst, and synthesis gas. It is a general metal-ion-supporting zeolite in which metal ions are supported on the zeolite used as the conversion reaction catalyst, and the method for regenerating the metal-ion-supporting zeolite catalyst of the present invention is, among others, the deposition of by-product impurities such as coke is remarkable, A catalyst for organic synthesis in which performance deterioration due to adhesion is a problem, especially one suitable as a regeneration method as a catalyst for a metal ion-supported zeolite used as a catalyst for producing an aromatic compound when producing an aromatic compound from a lower hydrocarbon Becomes Examples of the method for supporting the metal ions in that case include impregnation and supporting, ion exchange, and skeleton substitution.

The metal ion-supporting zeolite used as a catalyst for producing an aromatic compound has the following characteristics (i) to (iv) as a zeolite and carries 0.05 to 5 wt% of metal ions. Is preferred. In addition, the metal ion is not particularly limited, and since stable regeneration is possible among them, metal ions such as zinc ion, copper ion, silver ion, palladium ion, platinum ion, rhodium ion, iridium ion, and ruthenium ion. In particular, silver ion is preferable.
(I) The average particle size (hereinafter abbreviated as 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 amount of acid is 0.05 to 0.85 mmol/g, and particularly preferably 0.1 to 0.65 mmol/g.

The PD in (i) can be calculated and calculated from the outer surface area of zeolite using the following formula (1).
PD=6/S (1/2.29×10 ⁶ +0.18×10 ⁻⁶ ) (1)
(Here, S represents the external surface area (m ² /g).)
The external 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 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 for t is linearly approximated, and the outer surface area of the zeolite is determined from the slope of the regression line obtained.

Examples of the zeolite (ii) having a skeletal structure having a 10-membered ring structure include zeolites such as AEL, EUO, FER, HEU, MEU, MEL, MFI, and NES type. MFI, FER, and MEL-type zeolites are preferable, and MFI-type zeolites are particularly preferable because they are suitable for conversion reaction and isomerization reaction.

As for (iii) that the surface has no acid points, the surface acid point of the zeolite means the acid point existing on the surface of the zeolite, as the term implies. Usually, 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. Is. Then, since it is easy to prepare and obtain the zeolite, it is preferable that the zeolite has an unmodified surface whose surface is not coated with a silicate, a dialkylamine reagent, or the like.

Then, as the confirmation of the acid points on the surface of the zeolite (there is no acid point on the surface), any method can be used as long as the confirmation can be performed. Can be confirmed by adsorption of 2,4-dimethylquinoline (Characterization of acid sites on the external surface of zeolites, Reaction Kinetics and Catalysis Letters, vol. 67, 99) (p. 281). 2,4-Dimethylquinoline has an adsorption property with acid sites (-OH) existing on the surface of zeolite (including the surface inside pores), but the (micro)pore diameter of zeolite is 2,4-dimethylquinoline. If it is smaller than the quinoline molecule, it cannot penetrate into the (micro)pores and cannot adsorb with acid sites in the (micro)pores. That is, only the acid points on the zeolite surface are adsorbed. Therefore, when the adsorption of 2,4-dimethylquinoline to the acid points (-OH) existing on the surface of the zeolite is not observed, it can be determined that the acid points do not exist on the surface of the zeolite.

As a more specific method, infrared absorption spectrum measurement is performed at 150° C. of zeolite that has been degassed and dehydrated at 400° C. for 2 hours as pretreatment of zeolite. Then, 2,4-dimethylquinoline gas was introduced into the degassed/dehydrated zeolite and adsorbed for 10 minutes, and excess 2,4-dimethylquinoline was removed by exhausting at 150° C. to remove 2,4-dimethylquinoline. Adsorption zeolite is prepared and infrared absorption spectrum is measured at 150°C. That is, in the infrared absorption difference spectrum before and after 2,4-dimethylquinoline adsorption, if no difference (decrease) in infrared absorption can be confirmed in the range of 3600 to 3650 cm ⁻¹ , it is determined that there is no acid point on the surface. You can Note that 2,4-dimethylquinoline is also adsorbed on the silanol site on the surface of zeolite, but the absorption derived from the OH stretching vibration of silanol is observed at 3700 to 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. The decrease in the infrared absorption spectrum in the range of 3600 to 3650 cm ⁻¹ indicates that 2,4-dimethylquinoline is adsorbed on the surface acid points of the zeolite.

(Iv) The acid amount is 0.05 to 0.85 mmol/g, and particularly preferably 0.1 to 0.65 mmol/g. The activity of aromatization reaction of hydrocarbon becomes high. Incidentally, the acid amount in the zeolite is (iii) having no acid points on the surface, and therefore basically the acid amount of the acid points in the (micro)pores. The amount can be measured by using a method generally known as a method for measuring an acid amount, for example, ammonia-TPD method (solid acid property measurement by ammonia temperature programmed desorption method, catalyst, vol.42, p.218 (2000)). Specifically, at room temperature, the zeolite is saturatedly adsorbed with ammonia, heated to 100° C. to remove ammonia remaining in the measurement atmosphere, and then heated to 700° C. at a heating rate of 10° C./min. Among the peaks of ammonia measured in 1., the amount of ammonia desorbed on the high temperature side showing a strong acid point is used as the solid acid amount.

(Degradation of catalytic performance of metal ion supported zeolite catalyst)
Metal ion-supported zeolites include catalysts for organic synthesis, exhaust gas catalysts, hydrocarbon decomposition catalysts, isomerization reaction catalysts, aromatization reaction catalysts, hydrocracking reaction catalysts, alkylation reaction catalysts, synthesis gas conversion reaction catalysts, etc. When it is used as a catalyst, its catalytic performance is lowered, and it is regenerated as a catalyst by the regeneration method of the present invention, and metal ions are restored and redispersed at acid sites.

As an example of the reduction in catalytic performance, an example of producing an aromatic compound by contacting a lower hydrocarbon with the above-described metal ion-supported zeolite as a catalyst for producing an aromatic compound will be shown. In the metal ion-supported zeolite, metal ions are aggregated by the reaction to form metal clusters or metal particles, and the performance as a catalyst is deteriorated.

Examples of the lower hydrocarbons include aliphatic hydrocarbons and/or alicyclic hydrocarbons having 2 to 6 carbon atoms, and specifically, ethane, ethylene, propane, propylene, cyclopropane, n-butane, Isobutane, 1-butene, 2-butene, isobutene, butadiene, cyclobutene, cyclobutane, n-pentane, 1-pentane, 2-pentane, 1-pentene, 2-pentene, 3-pentene, n-hexane, 1-hexane, Examples thereof include 2-hexane, 1-hexene, 2-hexene, 3-hexene, hexadiene, cyclohexane and mixtures thereof, and further carbonization of petroleum such as naphtha having 4 carbon atoms. The C4 fraction, which is a hydrogen distillation mixture, the C5 fraction, which is a hydrocarbon distillation mixture having 5 carbon atoms, and the C6 fraction, which is a hydrocarbon distillation mixture having 6 carbon atoms, can also be mentioned.

The reaction temperature for producing an aromatic compound is not particularly limited as long as it is possible to produce an aromatic compound, and among them, the production of olefins or alkanes is suppressed, and an unnecessary heat-resistant reaction device is not required. The range of 400 to 800° C. is desirable because it results in an efficient reaction of aromatic compounds. Further, the reaction pressure is not limited, and the operation can be performed in a pressure range of, for example, about 0.05 MPa to 5 MPa. The supply of the reaction raw material, the aliphatic hydrocarbon and/or alicyclic hydrocarbon having 2 to 6 carbon atoms, to the catalyst for producing an aromatic compound is particularly limited as a ratio of the volume of the raw material gas to the catalyst volume. However, a space velocity of about ¹ h ^{−1 to} 50,000 h ⁻¹ can be used. When supplying an aliphatic hydrocarbon and/or alicyclic hydrocarbon having 2 to 6 carbon atoms as a raw material gas, a single aliphatic hydrocarbon and/or alicyclic hydrocarbon having 2 to 6 carbon atoms is used. It is also possible to use a gas, a mixed gas, or a gas obtained by diluting these with an inert gas such as nitrogen, a single gas or a mixed gas selected from hydrogen, carbon monoxide, and carbon dioxide.

The reaction form is not limited, and for example, a fixed bed, a transportation bed, a fluidized bed, a moving bed, a multitubular reactor, as well as a continuous flow type and an intermittent flow type reactor, etc. can be used.

The aromatic compound produced is not particularly limited as long as it belongs to the category called an aromatic compound, and for example, benzene, toluene, xylene, trimethylbenzene, ethylbenzene, propylbenzene, butylbenzene, naphthalene, Methylnaphthalene and the like can be mentioned, and benzene, toluene and xylene are particularly preferable.

(Regeneration of zeolite catalyst supporting metal ions)
The method for regenerating the metal ion-supported zeolite as a catalyst of the present invention is a catalyst for forming a metal cluster or metal particles in which metal ions are aggregated by using for a certain period of time as a catalyst by the production of the aromatic compounds exemplified above. The present invention relates to regeneration of a metal ion-supported zeolite catalyst that restores to the original metal ion and redisperses it to the acid site, and efficiently contacts with a gas having an oxygen content of 4 to 25% and 480 to 650°C. It becomes possible to restore the clusters of metal particles or metal particles to the original metal ions and redisperse them to the acid sites, and it is possible to suppress dealumination and restore the effect of the metal ions to suppress catalyst deterioration. When the oxygen content of the gas at this time is less than 4% or less than 480° C., the efficiency of restoring the original metal ions and redispersing to the acid sites is poor, or the effect of the metal ions is restored. Becomes difficult. Further, if the oxygen content of the gas exceeds 25%, or if it exceeds 650° C., the zeolite itself deteriorates and it becomes difficult to recover the catalyst performance.

As the gas, those having an oxygen content of 4 to 25% can be used, for example, those prepared by mixing air or oxygen with an inert gas such as nitrogen, argon, neon, or helium. At that time, it is possible to prepare with steam, but in some cases, it may cause a decrease in the specific surface area of the zeolite and a decrease in the acid sites, which may adversely affect the catalyst activity and the catalyst life.

In addition, the amount of gas supplied during regeneration may be any amount that enables the metal ions contained in the catalyst to be regenerated, and the amount of oxygen supplied by the regenerated gas/the content of metal ions in the metal ion-supported zeolite catalyst. The molar ratio may be 50 or more, and the upper limit is not particularly limited, but it is preferably supplied under conditions of 10,000 or less, particularly 2000 or less because of the regeneration efficiency or the effect of suppressing deterioration of the zeolite itself contained in the catalyst. .. The reproduction time is preferably 3 to 10 hours.

In the method for regenerating a metal ion-supported zeolite catalyst of the present invention, it is possible to take out a catalyst whose performance has deteriorated from the production process of an aromatic compound or the like and apply it separately as a regeneration process. It can also be applied as part of the manufacturing process.

The present invention, as a catalyst for reaction, use, production, etc., restores metal clusters or metal particles aggregated by the reaction of the metal ion-supported zeolite catalyst used for the reaction for a certain period to the original metal ions and redisperses them to the acid sites. This provides a method for regenerating a metal ion-supported zeolite catalyst that suppresses dealumination and suppresses catalyst deterioration, and is very useful industrially.

Hereinafter, specific examples of the present invention will be described as examples, but the present invention is not limited to these examples.

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

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

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

~SiO ₂ / _{Al 2 O 3} ratio, the measurement of the metal content -
The SiO ₂ /Al ₂ O ₃ molar ratio and the metal content of the zeolite are determined by dissolving the zeolite in a mixed aqueous solution of hydrofluoric acid and nitric acid, and using a common ICP device ((trade name) OPTIMA3300DV, manufactured by PerkinElmer). It was measured and determined by inductively coupled plasma optical emission spectroscopy (ICP-AES).

~ 2,4-Dimethylquinoline adsorption infrared absorption spectroscopy ~
For the measurement of infrared absorption spectrum, a general FT-IR measurement device ((trade name) Varian 660-IR, manufactured by Agilent Technologies, Inc.) is used for IR measurement device parts under vacuum ((trade name) multi-mode cell). , Manufactured by ST Japan) was used in combination. The sample was molded into a disk, placed in a cell, heated to 400° C. at 10° C./minute under vacuum exhaust, and held for 2 hours. After cooling to 150° C., the infrared absorption spectrum before 2,4-dimethylquinoline adsorption was measured. After introducing 2,4-dimethylquinoline gas, adsorbing it for 10 minutes, and evacuating at 150° C. for 1 hour, the infrared absorption spectrum after adsorbing 2,4-dimethylquinoline was measured. The difference between the infrared absorption spectrum after the adsorption of 2,4-dimethylquinoline and the spectrum before the adsorption was calculated, and the change in the infrared absorption due to the adsorption was measured.

-Method of measuring acid content-
A general NH ₃ -TPD apparatus ((trade name) BELCATII, manufactured by Microtrac Bell Co., Ltd.) and a gas analyzer ((trade name) BELMass, manufactured by Microtrac Bell Co., Ltd.) were used to measure the acid amount. .. The sample was made into granules, put in a cell, heated to 500° C. at 10° C./min in a helium atmosphere, and kept for 1 hour. Then, 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./minute, and the desorbed ammonia was analyzed by a gas analyzer. The acid amount of the sample was calculated from the remaining desorption amount excluding the weak acid-derived desorption amount.

-Measurement method of metal (silver) ion-
A UV-Vis apparatus (manufactured by JASCO Corporation, (trade name) V-770) was used for the measurement of metal (silver) ions. The sample was made into a powder, put in a cell, and measured at room temperature. The measurement range is 190 to 700 nm, and the slit width is 5 nm.

The absorption ranges of the metal (silver) ions, the aggregated metal (silver) clusters, and the metal (silver) particles were 190 to 240 nm, 240 to 350 nm, and 350 to 500 nm, respectively, and the abundance ratios were calculated from the peak area ratios.

-Aromatic compound manufacturing apparatus and manufacturing method thereof-
As the reaction apparatus, a fixed bed gas phase flow type reaction apparatus with a stainless reaction tube (inner diameter 16 mm, length 300 mm) was used. The middle stage of each stainless steel reaction tube was filled with a catalyst for producing an aromatic compound, preheated under a flow of dry air, and then fed with a raw material gas. The reactor conditions and operating conditions are not limited to the conditions described in this example, and can be selected as appropriate. For heating, a ceramic tubular furnace was used to control the temperature of the catalyst layer (reaction field). 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 components were 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 Sciences was used. The liquid component was analyzed using a gas chromatograph (manufactured by Shimadzu Corporation, (trade name) GC-2015) equipped with an FID detector. As the separation column, a capillary column (GL-1 (trade name) TC-1) was used.

Preparation example 1
An amorphous aluminosilicate gel was added to and suspended in an aqueous solution of tetrapropylammonium (hereinafter sometimes abbreviated as TPA) hydroxide and sodium hydroxide. MFI-type zeolite was added to the obtained suspension as a seed crystal to prepare a raw material composition. The amount of seed crystals added at that time was 0.7% with respect to the weight of Al ₂ O ₃ and SiO _{2 in} the raw material composition. In addition, ethanol produced as a by-product 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 for 4 days with stirring at 115° C. to obtain a slurry-like mixed liquid. The crystallized slurry-like mixed liquid was subjected to solid-liquid separation with a centrifugal settler, followed by washing solid particles with a sufficient amount of pure water and drying at 110° C. to obtain a dry powder.

The obtained dry powder was dispersed in 1 mol/l hydrochloric acid, filtered, and dried. After firing in air at 550° C. for 1 hour, it was treated with steam at 600° C. and 80% 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.

Comparing the infrared absorption difference spectra before and after adsorbing 2,4-dimethylquinoline on the obtained MFI zeolite, the peak derived from OH of the zeolite acid point at 3605 cm ⁻¹ did not decrease, and 3700 to 3800 cm ^The peak derived from OH of silanol of ^-1 was significantly reduced. Therefore, it was confirmed that 2,4-dimethylquinoline was adsorbed only on the silanol on the surface of the zeolite, and that there were no acid sites on the surface of the zeolite.

To 100 parts by weight of the obtained MFI-type zeolite, 43 parts by weight of silica (manufactured by Nissan Chemical Industries, (trade name) Snowtex N-30G), 4 parts by weight of cellulose, and 21 parts by weight of pure water were added and kneaded. Then, the kneaded material was formed into a cylindrical molded body having a diameter of 1.5 mm and a length of 1.0 to 7.0 mm (average length 3.5 mm). It was dried at 100° C. overnight.

27 g of the obtained MFI-type zeolite molded body was filled in a borosilicate glass tube having an inner diameter of 9.5 mm. The filling length was 70 cm. Separately, 4.08 g of silver nitrate was dissolved in 200 ml of pure water to prepare a 0.12 mol/l silver nitrate aqueous solution. A circulation pump was connected to the lower part of the glass tube using a chemical resistant polyolefin hose, and an aqueous silver nitrate solution was circulated for 2 hours in a dark place. The flow linear velocity at this time was 27 cm/min. After all the silver nitrate aqueous solution was extracted, 150 ml of pure water was circulated for 30 minutes at the same flow rate, and then all the washing liquid was extracted to measure the pH. Then, washing was repeated until the pH was within the range of 6 to 7.5. After washing, the zeolite was divided into four equal parts from the upper part to the lower part of the glass tube and collected in a magnetic dish, heated to 110° C. at a heating rate of 10° C./min, and dried overnight. Subsequently, the temperature was raised to 550° C. at a temperature rising rate of 1° C./min and dried for 6 hours. Among the four equal parts, the highest silver ion exchange rate was 80.4% and the lowest silver ion exchange rate was 81.1%. Therefore, the difference between the upper and lower silver ion exchange rates was 0.7%, and uniform silver ion exchange was achieved.

The silver ion content of the obtained silver ion-supported MFI-type zeolite molded product was 1.1 wt %. It had a 10-membered ring skeleton structure, the average particle diameter was 40 nm, the SiO ₂ /Al ₂ O ₃ molar ratio was 68, no acid points were present on the surface, and the acid amount was 0.20 mmol/g.

The abundance rates of silver ions, aggregated silver clusters and silver particles of the obtained silver ion-supported MFI type zeolite were 67%, 28% and 5%, respectively.

Preparation Example 2 (Production of aromatic compound)
The silver ion-supporting zeolite obtained in Preparation Example 1 was used as a catalyst for producing an aromatic compound, charged in the above-mentioned aromatic compound producing apparatus, and 1-butene was used as an aliphatic hydrocarbon as a raw material. A group compound was produced. The catalyst for producing an aromatic compound used at that time was found to have coke deposition and deteriorated in performance.
Reaction (catalyst) temperature: 600°C.
Circulating gas: 1-butene gas 40 ml/min+nitrogen 50 ml/min mixed gas.
Volume ratio of 1-butene gas to catalyst volume: 320/hour.
Catalyst weight: 3.75 g.
Reaction pressure: 0.1 MPa.
Reaction time: 48 hours.

Example 1
Under the following regeneration conditions, 0.2 g of the aromatic compound-producing catalyst used in Preparation Example 2 was used to restore aggregated silver clusters and silver particles to silver ions and redisperse them to acid sites.
Regeneration conditions: The temperature was raised from 450°C to 600°C over 4 hours. At this time, air was supplied at 2.1 ml/min. Then, the temperature was maintained at 600° C. and further continued for 40 minutes. The oxygen concentration supplied was 21%, and the molar ratio of oxygen amount in the regeneration gas supplied/silver content in the aromatic compound-producing catalyst was 250.

The abundance rates of silver ions, aggregated silver clusters, and silver particles of the obtained catalyst for producing a regenerated aromatic compound were 75%, 25%, and 0%, respectively. there were.

Example 2
Under the following regeneration conditions, 0.2 g of the aromatic compound-producing catalyst used in Preparation Example 2 was restored to the original silver ions from the aggregated silver clusters and silver particles, and redispersed at the acid sites.
Regeneration conditions: The temperature was raised from 450°C to 600°C over 4 hours. At this time, 2.1 ml/min of air and 2 ml/min of helium were supplied. Then, the temperature was maintained at 600° C. and further continued for 40 minutes. The oxygen concentration supplied was 11%, and the molar ratio of oxygen amount in the regeneration gas supplied/silver content in the aromatic compound-producing catalyst was 250.

The abundance rates of silver ions, aggregated silver clusters and silver particles of the obtained catalyst for producing a regenerated aromatic compound were 69%, 29% and 2%, respectively. there were.

Example 3
Under the following regeneration conditions, 0.2 g of the aromatic compound-producing catalyst used in Preparation Example 2 was restored to the original silver ions from the aggregated silver clusters and silver particles, and redispersed at the acid sites.
Regeneration conditions: The temperature was raised from 450°C to 600°C over 4 hours. At this time, air was supplied at 6.3 ml/min and helium was supplied at 24 ml/min. Then, the temperature was maintained at 600° C. and further continued for 1 hour. The oxygen concentration supplied was 4.4%, and the molar ratio of the amount of oxygen in the regeneration gas supplied/the amount of silver contained in the aromatic compound-producing catalyst was 800.

The abundance rates of silver ions, aggregated silver clusters, and silver particles of the obtained catalyst for producing regenerated aromatic compounds were 61%, 32%, and 7%, respectively, and the silver ion-supported zeolite was regenerated as a catalyst. there were.

Comparative Example 1
Under the following regeneration conditions, 0.2 g of the aromatic compound-producing catalyst used in Preparation Example 2 was used to restore the aggregated silver clusters and silver particles to the original silver ions and redisperse them to the acid sites.
Regeneration conditions: The temperature was raised from 450°C to 600°C over 4 hours. At this time, 2.1 ml/min of air and 15 ml/min of helium were supplied. Then, the temperature was maintained at 600° C. and further continued for 40 minutes. The oxygen concentration supplied was 2.6%, and the molar ratio of the amount of oxygen in the regeneration gas supplied/the content of silver in the aromatic compound-producing catalyst was 250.

The abundance rates of silver ions, aggregated silver clusters and silver particles of the obtained catalyst were 47%, 31% and 22%, respectively, and many aggregated silver clusters and silver particles still remained. , Was not regenerated as a catalyst.

Comparative example 2
Under the following regeneration conditions, 0.2 g of the aromatic compound-producing catalyst used in Preparation Example 2 was used to restore aggregated silver clusters and silver particles to the original silver ions and to redisperse them to acid sites.
Regeneration conditions: The temperature was raised from 450°C to 600°C over 4 hours. At this time, 2.1 ml/min of air and 30 ml/min of helium were supplied. Then, the temperature was maintained at 600° C. and further continued for 40 minutes. The oxygen concentration supplied was 1.4%, and the molar ratio of oxygen amount in the regeneration gas supplied/silver content in the aromatic compound-producing catalyst was 250.

The abundance rates of silver ions, aggregated silver clusters and silver particles of the obtained catalyst were 32%, 37% and 31%, respectively, and many aggregated silver clusters and silver particles still remained. , Was not regenerated as a catalyst.

Comparative Example 3
Under the following regeneration conditions, 0.2 g of the aromatic compound-producing catalyst used in Preparation Example 2 was used to restore the aggregated silver clusters and silver particles to the original silver ions and redisperse them to the acid sites.
Regeneration conditions: The temperature was raised from 450°C to 600°C over 4 hours. At this time, 2.1 ml/min of air and 30 ml/min of helium were supplied. Then, the temperature was maintained at 600° C. and further continued for 1 hour. The oxygen concentration supplied was 1.4%, and the molar ratio of the oxygen amount in the regeneration gas supplied/the silver content in the aromatic compound-producing catalyst was 270.

The abundance rates of silver ions, aggregated silver clusters and silver particles in the obtained catalyst were 46%, 43% and 11%, respectively, and many aggregated silver clusters and silver particles still remained. , Was not regenerated as a catalyst.

Comparative Example 4
Under the following regeneration conditions, 0.2 g of the aromatic compound-producing catalyst used in Preparation Example 2 was used to restore the aggregated silver clusters and silver particles to the original silver ions and redisperse them to the acid sites.
Regeneration conditions: The temperature was raised from 450°C to 600°C over 4 hours. At this time, 2.1 ml/min of air and 30 ml/min of helium were supplied. Then, the temperature was maintained at 600° C. and further continued for 2 hours. The oxygen concentration supplied was 1.4%, and the molar ratio of the oxygen amount in the regeneration gas supplied/the silver content in the aromatic compound-producing catalyst was 320.

The abundance rates of silver ions, aggregated silver clusters and silver particles in the obtained catalyst were 43%, 38% and 19%, respectively, and many aggregated silver clusters and silver particles still remained. , Was not regenerated as a catalyst.

Comparative Example 5
Under the following regeneration conditions, 0.2 g of the aromatic compound-producing catalyst used in Preparation Example 2 was used to restore aggregated silver clusters and silver particles to the original silver ions and to redisperse them to acid sites.
Regeneration conditions: The temperature was raised from 450°C to 600°C over 4 hours. At this time, 2.1 ml/min of air and 30 ml/min of helium were supplied. Then, the temperature was maintained at 600° C. and further continued for 3 hours. The oxygen concentration supplied was 1.4%, and the molar ratio of the oxygen amount in the regeneration gas supplied/the silver content in the aromatic compound-producing catalyst was 370.

The abundance rates of silver ions, aggregated silver clusters and silver particles of the obtained catalyst were 46%, 36% and 18%, respectively, and many aggregated silver clusters and silver particles still remained. , Was not regenerated as a catalyst.

INDUSTRIAL APPLICABILITY The present invention suppresses dealumination by restoring aggregated metal clusters or metal particles in a metal ion-supported zeolite catalyst used for a certain period of time due to reaction, production, use, etc., and redispersing them to acid points. The present invention provides a method for regenerating a metal ion-supported zeolite catalyst that suppresses catalyst deterioration, and is industrially very useful.

Claims (5)

A method for regenerating a metal ion-supported zeolite catalyst, comprising contacting the used metal ion-supported zeolite catalyst with a gas having an oxygen content of 4 to 25% and 480 to 650°C. The regeneration of the metal ion-supported zeolite catalyst according to claim 1, wherein the molar ratio of the amount of oxygen supplied when contacting the gas/the content of the metal ion in the metal ion-supported zeolite catalyst is 50 to 2000. Method. The method for regenerating a metal ion-supported zeolite catalyst according to claim 1 or 2, which is a step of restoring metal clusters and metal particles in which metal ions are aggregated to metal ions. The method for regenerating a metal ion-supported zeolite catalyst according to any one of claims 1 to 3, wherein the metal ion-supported zeolite catalyst has the following characteristics (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 amount of acid is 0.05 to 0.85 mmol/g. The metal ion-supported zeolite catalyst according to claim 1, wherein the metal ion-supported zeolite catalyst is selected from the group consisting of MFI-type zeolite, MEL-type zeolite and FER-type zeolite. How to play.