JP7087636B2 - Zeolite catalyst treatment method and lower olefin production method - Google Patents

Description

The present invention relates to a method for treating a zeolite catalyst and a method for producing a lower olefin. The present invention relates to a method for treating a zeolite catalyst to be contacted with, and a method for producing a lower olefin using the method for treating the zeolite catalyst.

Conventionally, as a method for producing lower olefins such as ethylene, propylene and butenes, a naphtha steam cracking method and a fluidized catalytic cracking method of vacuum gas oil are mentioned, and a naphtha steam cracking method is mainly carried out. However, in the steam cracking method, ethylene is produced as a main component, and it is difficult to significantly change the production ratio of each olefin. Further, in recent years, an MTO (methanol to olefin) process using methanol and / or dimethyl ether as a raw material has been known.

For example, Patent Document 1 uses a catalyst containing CHA-type siliconaluminophosphate (SAPO-34) having 8-membered ring pores as an active ingredient as a method for producing a lower olefin using methanol or dimethyl ether as a raw material. , A method for producing a lower olefin containing ethylene and propylene as main components in a high yield is disclosed. On the other hand, when producing the lower olefin, the activity of the zeolite catalyst may decrease with the passage of time. Therefore, Patent Document 2 discloses, for example, as a method for recovering the catalytic activity, a method for burning and regenerating a zeolite catalyst in which cork has accumulated with a gas containing oxygen in a reaction for producing a lower olefin from an oxygenate. Has been done. Further, Patent Document 3 describes a method (stripping) for recovering a light boiling hydrocarbon component other than cork remaining in the zeolite catalyst pores before regeneration of the catalyst in a conversion reaction of an oxygenate raw material such as methanol. It has been disclosed.

US Pat. No. 5,914,433 US Patent Application Publication No. 2005/0215840 US Patent Application Publication No. 2004/0034178

However, according to the studies by the present inventors, it has been found that the above-mentioned known methods have various problems and are not always satisfactory. That is, Patent Document 2 discloses a method of activating the catalytic activity by combustion regeneration with a gas containing oxygen, but at the time of combustion, in addition to oxygen, a light boiling hydrocarbon component and cork accumulated in a zeolite catalyst are used. In addition to the problem that the light-boiling hydrocarbon component and cork component remaining in the catalyst are lost as low-value-added components because carbon monoxide, carbon dioxide, and water are generated by the combustion of the catalyst, the high temperature Since water vapor comes into contact with the zeolite catalyst underneath, there is a problem that permanent deterioration of the zeolite catalyst is likely to occur.

Further, as in Patent Document 3, it is said that a part of the light boiling hydrocarbon component other than cork can be recovered by introducing a stripping step before the combustion regeneration treatment, but the number of steps and equipment As the number increases, energy costs tend to increase. As the stripping gas, in a system that produces water such as a methanol conversion reaction, unreacted methanol and dimethyl ether are adsorbed on the zeolite active site in addition to the generated light boiling hydrocarbon component and water. In order to perform efficient stripping, water (water vapor) having a high adsorption ability to the zeolite active site is most preferably used as the stripping gas. Thereby, the gas containing the light boiling hydrocarbon component and water (steam) recovered by stripping can be mixed with the product gas at the outlet of the methanol conversion reactor and separated and purified by the same process. On the other hand, as described above, since water vapor comes into contact with the zeolite catalyst, there is a problem that the activity is likely to decrease due to permanent deterioration of the catalyst.

As described above, in the conventional MTO process, a method of simultaneously performing stripping to recover the lightly boiling hydrocarbon component in the zeolite catalyst and regeneration by removing cork in the zeolite catalyst has not been known. Therefore, the present invention efficiently strips and recovers the hydrocarbon component in the zeolite catalyst from the viewpoint of reducing the plant construction cost and the manufacturing cost, and at the same time, exhibits the catalytic activity without causing permanent deterioration of the zeolite catalyst due to steam or the like. It is an object of the present invention to provide a method for treating a recovering zeolite catalyst and a method for producing a lower olefin using the zeolite catalyst.

As a result of diligent studies to solve the above problems, the present inventors have specified a catalyst after undergoing a reaction in which a raw material containing methanol and / or dimethyl ether is brought into contact with a zeolite catalyst to produce a lower olefin. It has been found that the lower olefin can be efficiently and stably produced without causing permanent deterioration of the zeolite catalyst by performing the above-mentioned treatment, and the present invention has been achieved.

That is, the gist of the present invention is as follows.
[1] A zeolite catalyst that has undergone a reaction in which a raw material containing methanol and / or dimethyl ether is brought into contact with a zeolite catalyst to produce a lower olefin is brought into contact with a gas containing hydrogen having an absolute hydrogen partial pressure of 0.01 MPa or more. A method for treating a zeolite catalyst, which comprises a step.
[2] The method for treating a zeolite catalyst according to [1], wherein the zeolite constituting the zeolite catalyst is an oxygen 8-membered ring-structured zeolite.
[3] [1] or [1] or [3], in which the zeolite constituting the zeolite catalyst contains d6r, which is defined as a composite building unit by the International Zeolite Association (IZA), in the skeleton.
2] The method for treating a zeolite catalyst according to the above method.
[4] The method for treating a zeolite catalyst according to any one of [1] to [3], wherein the zeolite constituting the zeolite catalyst is an aluminosilicate.
[5] The zeolite constituting the zeolite catalyst is a zeolite having CHA or ERI under the code defined by the International Zeolite Association (IZA), [1] to
The method for treating a zeolite catalyst according to any one of [4].
[6] The method for treating a zeolite catalyst according to any one of [1] to [5], wherein the amount of acid on the outer surface of the zeolite constituting the zeolite catalyst is 8% or less with respect to the total amount of acid of the zeolite. [7] The method for treating a zeolite catalyst according to any one of [1] to [6], wherein the contact temperature is 250 ° C. or higher and 800 ° C. or lower in the step of contacting with the gas containing hydrogen.
[8] A method for producing a lower olefin, comprising a step of contacting a raw material containing methanol and / or dimethyl ether with a zeolite catalyst, wherein the treatment method according to any one of [1] to [7] is carried out. A method for producing a lower olefin including.

According to the present invention, in a method for producing a lower olefin by contacting a raw material containing methanol and / or dimethyl ether with a catalyst containing zeolite, the hydrocarbon component accumulated in the zeolite pores through the reaction is efficiently expelled. And the catalytic activity can be restored. As a result, the yield can be maintained even after the production of the lower olefin for a long time.

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

In the present invention, a zeolite catalyst having an increased hydrocarbon content through a reaction in which a raw material containing methanol and / or dimethyl ether is brought into contact with a catalyst containing zeolite to form a lower olefin, and the hydrogen partial pressure is 0. The present invention relates to a method for treating a zeolite catalyst and a method for producing a lower olefin, which are brought into contact with a gas containing hydrogen of 01 MPa or more. In the present invention, the zeolite catalyst means a catalyst containing zeolite. Hereinafter, the present invention will be described in detail.

<1. Zeolite catalyst ＞
Zeolites are crystalline substances in which _TO4 units (T is the central atom) with a tetrahedral structure share an O atom and are three-dimensionally connected to form open regular micropores. Point to. Specifically, silicates, phosphates, germanium salts, arsenates, etc. described in the structural committee data collection of the International Zeolite Association (hereinafter referred to as "IZA") are used. included.

Here, the silicate includes, for example, aluminosilicate, galosilicate, ferricate, titanosilicate, borosilicate and the like.
Phosphates include, for example, aluminophosphates, gallophosphates, verilophosphates and the like.
The germanium salt includes, for example, an aluminogermanium salt, and the arsenate includes, for example, an aluminohydrate.
Further, the aluminophosphate includes, for example, silicoaluminophosphate in which the T atom is partially substituted with Si, and those containing divalent or trivalent cations such as Ga, Mg, Mn, Fe, Co and Zn. ..

The average pore diameter of the zeolite is not particularly limited, and is usually 0.55 nm or less, preferably 0.50 nm or less, more preferably 0.45 nm or less, still more preferably 0.40 nm or less. Here, the average pore diameter indicates a crystallographic free diameter of the channels defined by IZA. The average pore diameter of 0.55 nm or less means that when the shape of the pore (channel) is a perfect circle, the average diameter is 0.55 nm or less, but when the shape of the pore is elliptical, it means. It means that the minor axis is 0.55 nm or less.

By using a zeolite having an average pore diameter of 0.55 nm or less, a lower olefin can be produced in high yield using methanol as a raw material. That is, if the average pore diameter is in the above range, it is considered that lower olefins can be more selectively generated in the zeolite crystal and that the removal of hydrocarbons under the hydrogen atmosphere described later proceeds efficiently. ..

From the above viewpoint, in the present invention, the zeolite is preferably an oxygen 8-membered ring-structured zeolite.

The oxygen 8-membered ring-structured zeolite has a framework type code defined by IZA, and preferably, for example, AEI, AFX, CHA, ERI, KFI, LEV, SAS, SAV, SZR, PAU, RHO, LTA and the like. Can be mentioned.

The framework density (unit: T / nm ³ ) of the zeolite is not particularly limited, and is usually 20.0 or less, preferably 18.0 or less, more preferably 17.0 or less, still more preferably 16.0 or less. It is usually 12.0 or more, preferably 14.0 or more, and more preferably 14.5 or more.
Here, the framework density (unit: T / nm ³ ) is the number of T atoms (atoms other than oxygen among the atoms constituting the skeleton of zeolite) existing per unit volume (1 nm ³ ) of zeolite. Meaning, this value is determined by the structure of the zeolite.

From these viewpoints, the oxygen 8-membered ring-structured zeolite is preferably a zeolite containing d6r in the skeleton, which is defined by the International Zeolite Association (IZA) as a composite building unit, and more preferably AEI, AFX, CHA, ERI, and so on. KFI, LEV, SAV, more preferably AEI, AFX, CHA, or ERI, particularly preferably AEI, CHA, or ERI, particularly preferably CHA or ERI, and most preferably ERI. ..

Specific examples of the oxygen 8-membered ring-structured zeolite include silicates and phosphates. As described above, the silicate includes, for example, aluminosilicate, galosilicate, ferricate, titanosilicate, borosilicate and the like, and the phosphate includes aluminophosphate and silicon composed of aluminum and phosphorus. Examples thereof include siliconaluminophosphate, which is composed of aluminum and phosphorus. Among these, aluminosilicate and siliconaluminophosphate are preferable, and aluminosilicate is more preferable.

As the zeolite, a proton exchange type is usually used, but some of them are alkali metals such as Li, Na, K, Rb and Cs, alkaline earth metals such as Mg, Ca, Sr and Ba, Cr, Cu and Ni, It may be replaced with a transition metal such as Fe, Mo, W, Pt, or Re. In this case, the zeolite may be subjected to an ion exchange treatment described later.

In addition to these ion exchange sites, 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 by the metal. May be 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.

When the zeolite is a silicate, SiO ₂ / M ₂ O ₃ (however, the denominator of the molar ratio represents the total amount of Al ₂ O ₃ , Ga ₂ O ₃ , B ₂ O ₃ and Fe ₂ O ₃ ) mol. The ratio is usually 5 or more, preferably 8 or more, more preferably 10 or more, still more preferably 15 or more, usually less than 100, preferably 80 or less, more preferably 60 or less, still more preferably 40 or less. be. The above ratio is a value obtained on the assumption that all Si atoms in the zeolite are contained as SiO ₂ and all the M contained in the zeolite is contained as M ₂ O ₃ . When the SiO ₂ / M ₂ O ₃ molar ratio is in the above range, the amount of acid derived from the strong acid point and the weak acid point can be sufficiently obtained, and high methanol adsorption capacity, high methanol conversion activity and olefin interconversion activity can be obtained. 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. The SiO ₂ / M ₂ O ₃ molar ratio 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 line of the fluorescent X-ray intensity of the analysis element in the standard sample and the atomic concentration of the analysis element, and this calibration line 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.

When the zeolite is a phosphate, the (Al + P) / Si molar ratio of silicoaluminophosphate or (Al + P) / M of metalloaluminophosphate having a divalent metal (where M indicates a divalent metal). The molar ratio is usually 5 or more, preferably 10 or more, and usually 500 or less, preferably 100 or less. Specific examples of the divalent metal include Ga, Mg, Mn, Fe, Co and Zn. When it is at least the above lower limit, it is possible to prevent the durability of the catalyst from being lowered, and when it is at least the above upper limit, it is possible to prevent the catalyst activity from being lowered.

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 the outer surface acid amount). ) Is the sum. The total acid amount is not particularly limited, but is usually 0.01 mmol / g or more, preferably 0.10 mmol / g or more, more preferably 0.20 mmol / g or more, still more preferably 0.30 mmol / g or more. Is. Further, it is usually 2.0 mmol / g or less, preferably 1.5 mmol / g or less, more preferably 1.0 mmol / g or less, still more preferably 0.80 mmol / g or less. By setting the total amount of acid in the above range, the conversion activity of methanol is ensured, coke formation inside the pores of zeolite is suppressed, and the diffusibility in the crystal of the molecule is increased, so that lower olefins are formed. Can be promoted. The total acid amount here is calculated from the desorption amount in the ammonia heated desorption ( _NH3 -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. The obtained zeolite is vacuum dried at 100 ° C. or brought into contact with steam at 100 ° C. to remove excess ammonia from the zeolite. 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.

The amount of acid on the outer surface of the zeolite is not particularly limited, but is usually 8% or less, preferably 5% or less, more preferably 3% or less, still more preferably 1% or less, based on the total acid amount of the zeolite. , Most preferably 0%. If the amount of outer surface acid is too large, the yield of lower olefins tends 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 amount of acid on the outer surface of the zeolite is not particularly limited, but can be adjusted by silylation treatment, steam treatment, heat treatment, acid treatment, ion exchange treatment and the like.

<Cyrilization treatment>
The method for silylating the zeolite is not particularly limited, and a known method can be appropriately used, and specifically, liquid phase silylation, gas phase silylation and the like can be performed.

It is considered that the acid spots on the outer surface of zeolite are usually covered with the acid spots on the outer surface and inactivated by the silylation treatment, so that the amount of acid on the outer surface is reduced. When the amount of acid on the outer surface decreases, side reactions that occur on the outer surface of the zeolite are suppressed. Specifically, the conversion reaction of methanol causes the lower olefins produced in the zeolite pores to come into contact with the acid spots on the outer surface of the zeolite, which has the effect of suppressing the reaction of components other than the target substance. Conceivable. Further, in the silylation of the outer surface acid points, since the silyl group is also bonded to the acid points constituting the pores of the zeolite, the pore diameter of the outer surface opening is slightly reduced and the molecular diffusion to the outside of the crystal is performed. It is also considered to have the effect of suppressing. It is considered that this makes it possible to suppress the formation of hydrocarbons having 5 or more carbon atoms, which are larger molecules, and improve the selectivity of lower olefins.
Hereinafter, the silylation treatment will be specifically described by taking liquid phase silylation as an example.

The silylating agent is not particularly limited, and usually, an agent capable of silylating the outer surface of the zeolite and not being able to silylate the inside of the pores of the zeolite is used. Specifically, silicones, chlorosilanes, alkoxysilanes, siloxanes, silazanes and the like can be used. Of these, chlorosilanes are usually used for gas phase silylation, and alkoxysilanes are usually used for liquid phase silylation, and more preferable silylating agents are highly reactive and relatively easy to handle. , Alkoxysilanes.
Specific examples of silicones include dimethyl silicone, diethyl silicone, phenylmethyl silicone, methylhydrogen silicone, ethylhydrogen silicone, phenylhydrogen silicone, methylethyl silicone, phenylethyl silicone, diphenyl silicone, and methyltrifluoropropyl silicone. , Ethyltrifluoropropyl Silicone, Tetrachlorophenyl Methyl Silicone, Tetrachlorophenyl Ethyl Silicone, Tetrachlorophenyl Hydrogen Silicone, Tetrachlorophenyl Silicone, Methyl Vinyl Silicone, Ethyl Vinyl Silicone and the like are used.

Specific examples of the chlorosilanes include tetrachlorosilane, trichlorosilane, trichloromethylsilane, dichlorodimethylsilane, chlorotrimethylsilane, trichloroethylsilane, dichlorodiethylsilane, and chlorotriethylsilane.
Specific examples of the alkoxysilanes include quaternary alkoxysilanes such as tetramethoxysilane and tetraethoxysilane; and tertiary alkoxysilanes such as trimethoxymethylsilane, trimethoxyethylsilane, triethoxymethylsilane, and triethoxyethylsilane. Secondary alkoxysilanes such as alkoxysilanes, dimethoxydimethylsilanes, dimethoxydiethylsilanes, diethoxydimethylsilanes, diethoxydiethylsilanes; primary alkoxysilanes such as methoxytrimethylsilanes, methoxytriethylsilanes, ethoxytrimethylsilanes, and ethoxytriethylsilanes; Is used. It is preferably a secondary or higher alkoxysilane, more preferably a tertiary or higher alkoxysilane, and even more preferably a quaternary alkoxysilane.

Specific examples of the siloxanes include hexamethyldisiloxane, hexaethyldisiloxane, pentamethyldisiloxane, tetramethyldisiloxane, and the like, with hexamethyldisiloxane being preferred.
Specific examples of the silazanes include hexamethyldisilazane, dipropyltetramethyldisilazane, diphenyltetramethyldisilazane, tetraphenyldimethyldisilazane and the like, and hexamethyldisilazane is preferable.

The amount of the silylating agent for the zeolite is not particularly limited, but is usually 0.001 mol or more, preferably 0.01 mol or more, and more preferably 0.1 mol or more with respect to 1 mol of the zeolite. Is. Further, it is usually 5 mol or less, preferably 3 mol or less, and more preferably 1 mol or less. By setting the amount of the silylating agent in the above range, the silylation coating of the outer surface acid spots proceeds efficiently, and the decrease in catalytic activity due to the excessive silylation coating can be suppressed, which is preferable. The amount of the silylating agent is represented by the number of moles of Si atoms contained in the silylating agent, and in the case of a silylating agent having a plurality of Si atoms in the molecule, the total number of moles of the Si atoms is silyl. It will be treated as the number of moles of the agent.

When liquid phase silylation is performed, a solvent can be used, and the solvent is not particularly limited, but hydrocarbons such as hexane, heptane, octane, nonane, decane, cyclopentane, cyclohexane, benzene, toluene and xylene. And water can be used. When liquid phase silylation is performed with an aqueous solvent, an acidic aqueous solution to which an acid such as sulfuric acid or nitric acid is added can be used in order to promote the silylation reaction.

When liquid phase silylation is performed, the concentration of the silylating agent in the solution for which the liquid phase silylation reaction is performed is not particularly limited, but is usually 0.01% by mass or more, preferably 0.5% by mass. As mentioned above, it is more preferably 1% by mass or more. Further, it is usually 80% by mass or less, preferably 60% by mass or less, and more preferably 40% by mass or less. By setting the concentration of the silylating agent in the above range, condensation between the silylating agents can be suppressed and the silylation rate can be maintained, which is preferable.

The amount of the solvent for the zeolite in the case of performing liquid phase silylation is not particularly limited, but is usually 1 g or more, preferably 3 g or more, and more preferably 5 g or more with respect to 1 g of the zeolite. Further, it is usually 100 g or less, preferably 80 g or less, and more preferably 50 g or less. By setting the amount of the solvent in the above range, it is preferable in that sufficient stirring efficiency of the slurry can be obtained and a certain productivity can be ensured.

When liquid phase silylation is performed, a specific range of water may be added to the zeolite to be subjected to the silylation treatment. The water contained in the zeolite may be originally contained in the zeolite, or may be artificially supplied with water to adjust the water content to a specific range. Usually, as the zeolite of the present invention, a zeolite obtained by hydrothermal synthesis is calcined, and if necessary, it is converted into an ammonium type and then calcined to be converted into a proton type. Therefore, it is usually assumed that the water content of the zeolite before the silylation treatment is very small, and the zeolite may be subjected to the silylation treatment as it is, or the zeolite is supplied with water so as to have a specific water content. The water content may be adjusted before use (hereinafter, may be referred to as humidity control treatment).

The water content is not particularly limited, but the weight of water contained in the zeolite is expressed in mass% with respect to the weight of the dry zeolite, and is usually 30% by mass or less, preferably 25% by mass or less, as a lower limit. Is 0% by mass in a completely dry state. By setting the water content within the above range, the silylation coating of the outer surface acid spots proceeds efficiently, and pore clogging due to excessive silylation can be prevented, which is preferable.

The humidity control treatment method is not particularly limited as long as it can be adjusted to a predetermined water content. For example, a method of leaving zeolite in an atmosphere having an appropriate relative humidity, a method of allowing zeolite to coexist in a closed container (decicator, etc.) with a saturated aqueous solution of water or an inorganic salt and leaving it in a saturated steam atmosphere, zeolite. In addition, a method of circulating a gas having an appropriate water vapor pressure can be mentioned. In the above method, in order to perform more uniform humidity control, the humidity control treatment may be performed while mixing or stirring zeolite.

The temperature at which the silylation treatment is performed is appropriately adjusted depending on the type of silylating agent and solvent used, and is not particularly limited, but is usually 20 ° C. or higher, preferably 40 ° C. or higher, and more preferably 60 ° C. or higher. .. Further, it is usually 140 ° C. or lower, preferably 120 ° C. or lower, and more preferably 100 ° C. or lower. By setting the silylation treatment temperature within the above range, the discharge of water in the zeolite pores is suppressed, so that the silylation coating of the outer surface acid spots proceeds efficiently.
Moreover, it is preferable in that the silylation rate can be maintained.

The time required to raise the temperature from the addition of the silylating agent to the silylation temperature is not particularly limited, and the silylating agent may be added at the silylation temperature, but usually 0.01 hours. As described above, it is preferably 0.05 hours or more, more preferably 0.1 hours or more, and there is no particular upper limit to the time required for raising the temperature. When the silylation temperature is high, by setting the time required for raising the temperature within the above range, the discharge of water from the pores of the zeolite is suppressed, so that the hydrolysis and polymerization reaction of the silylating agent in the solution Is suppressed, and silylation of the zeolite proceeds efficiently, which is preferable.

The treatment time for silylation depends on the reaction temperature, but is usually 0.1 hours or more, preferably 0.5 hours or more, more preferably 1 hour or more, and the treatment time is as long as the performance of the catalyst is not impaired. There is no particular upper limit for. By setting the treatment time within the above range, the silylation coating of the outer surface acid points of the zeolite proceeds, and the amount of the outer surface acid is sufficiently reduced, which is preferable.

<Steam treatment>
The steam treatment method is not particularly limited, but can be brought into contact with a gas containing steam as long as the effect of the present invention is not impaired. Specific examples thereof include a method of contacting with water vapor, water vapor diluted with air or an inert gas, a reaction atmosphere containing water vapor together with methanol and / or dimethyl ether, a reaction atmosphere for generating water vapor, and the like. The reaction that produces water vapor is a reaction that causes dehydration to generate water vapor, such as the dehydration reaction of methanol and / or dimethyl ether. Depending on the conditions, water vapor may partially exist as liquid water, but in order to give the zeolite a uniform water vapor treatment effect, it is preferable that the whole is present in the state of water vapor.

It is considered that not only the amount of the outer surface acid but also the total acid amount of the zeolite is reduced because the T atoms other than silicon forming the skeleton of the zeolite are desorbed from the skeleton of the entire crystal by steam treatment. This decrease in the total amount of acid suppresses the formation of cork inside the pores of the zeolite and improves the diffusivity of the molecule in the crystal. Therefore, it is presumed that the production of linear butene, which is a molecule larger than propylene, is relatively promoted.
When excessive water vapor treatment is performed, the diffusibility of the molecule in the crystal increases more than necessary, and the amount of hydrocarbon molecules having 5 or more carbon atoms such as pentene and hexene tends to increase.

The steam treatment temperature is not particularly limited, but is usually 500 ° C. or higher, preferably 600 ° C. or higher, and more preferably 700 ° C. or higher. Further, it is usually 1000 ° C. or lower, preferably 900 ° C. or lower, and more preferably 800 ° C. or lower. By setting the steam treatment temperature in the above range, it is preferable that T atoms other than silicon can be efficiently removed from the skeleton in a short treatment time without causing the collapse of the skeleton structure.

The steam used for steam treatment can be diluted with air or an inert gas such as helium or nitrogen before use. The water vapor concentration at that time is not particularly limited, but is usually 5% by volume or more, preferably 20% by volume or more, and more preferably 35% by volume or more with respect to the total gas used for steam treatment of the zeolite. It is more preferably 50% by volume or more, usually 100% by volume or less, preferably 90% by volume or less, more preferably 80% by volume or less, still more preferably 70% by volume or less.
The upper limit is not particularly limited, and 100% by volume of steam can be used. By setting the water vapor concentration in the above range, the T atom can be efficiently removed from the skeleton in a short treatment time, which is preferable.

The pressure of steam treatment (total pressure including diluting gas) is not particularly limited, but is usually 50.
It is kPa (absolute pressure, the same applies hereinafter) or more, preferably 75 kPa or more, more preferably 100 kPa or more, and usually 2 MPa or less, preferably 1 MPa or less, more preferably 0.5 MPa or less. By setting the pressure of steam treatment within the above pressure range, the T atom can be efficiently removed from the skeleton in a short time, which is preferable.

The partial pressure of water vapor is not particularly limited, but is usually 0.01 MPa or more (absolute pressure, the same applies hereinafter), preferably 0.03 MPa or more, more preferably 0.05 MPa or more, and usually 3 MPa or less, preferably 3 MPa or less. It is 1 MPa or less, more preferably 0.5 MPa or less, still more preferably 0.2 MPa or less. By setting the partial pressure of water vapor within the above pressure range, the T atom can be efficiently removed from the skeleton in a short time, which is preferable.

The steam treatment time is not particularly limited, but is usually 0.1 hours or more, preferably 0.5 hours or more, and more preferably 1 hour or more. Further, there is no upper limit of the treatment time as long as the catalytic activity is not significantly inhibited. The treatment time can be appropriately adjusted depending on the steam treatment temperature and the steam concentration.

The steam treatment may be performed in a state where an organic substance is present inside the pores. The presence of the organic substance inside the pores makes it possible to significantly reduce the acid points on the outer surface while preventing an extreme decrease in the acid points inside the pores, especially when a strong steam treatment is performed.
Examples of the organic substance include, but are not limited to, a structure-defining agent used during hydrothermal synthesis of zeolite, cork produced by the reaction, and the like. These organic substances can be removed by steam treatment of zeolite after hydrothermal synthesis (hereinafter, referred to as zeolite before firing) and then through a combustion step such as air firing, or an oxygen-containing gas such as air. By treating with steam diluted with, it is also possible to treat with steam while removing organic substances.

It is also possible to physically mix the zeolite with a compound containing an alkaline earth metal before subjecting it to steam treatment. By adding an alkaline earth metal, it may be possible to neutralize the strong acid point of the zeolite and suppress the formation of cork produced at the strong acid point. Examples of the compound containing an alkaline earth metal include calcium carbonate, calcium hydroxide and magnesium carbonate, and calcium carbonate is preferable.
The amount of the compound containing an alkaline earth metal is not particularly limited, but is usually 0.5% by mass or more, preferably 3% by mass or more, usually 30% by mass or less, preferably 10% by mass or less with respect to the zeolite. be.

<Heat treatment>
The method for heat treatment is not particularly limited, but specifically, a method for treating the zeolite at a high temperature in at least one atmosphere selected from air and an inert gas, and a method containing methanol and / or dimethyl ether are included. Examples thereof include a method of high temperature treatment in a mixed gas atmosphere. This makes it possible to reduce the total amount of acid in the zeolite.

The heat treatment temperature is not particularly limited, but is usually 600 ° C. or higher, preferably 700 ° C. or higher, more preferably 800 ° C. or higher, usually 1200 ° C. or lower, preferably 1000 ° C. or lower, more preferably 900 ° C. or lower. be. By setting the heat treatment temperature in the above range, it is preferable that the T atom can be efficiently removed from the skeleton in a short treatment time without causing the collapse of the skeleton structure.

As the gas type used in the heat treatment, helium, nitrogen, air or the like can be used.
Similar to the steam treatment, the heat treatment may be performed in a state where an organic substance is present inside the pores. When an inert gas such as helium or nitrogen is used, the organic substance may be carbonized by heat treatment, but it can be removed by firing with air.

The heat treatment may be performed at the same time as the firing performed when the above-mentioned zeolite is produced, or may be separately performed separately. The heat treatment is performed at a relatively high temperature for the purpose of desorption of the T atom in the skeleton, and is not particularly limited. Specifically, if the above firing and the heat treatment are performed separately, the heat treatment is performed. Is usually carried out at a temperature higher than that of firing.
The heat treatment time is not particularly limited, but is usually 0.1 hours or longer, preferably 0.5 hours or longer, and more preferably 1.0 hour or longer. Further, there is no upper limit of the treatment time as long as the catalytic activity is not significantly impaired, and the treatment time can be appropriately adjusted depending on the heat treatment temperature.

<Acid treatment>
The method for acid treatment of zeolite of the present invention is not particularly limited, and specific examples thereof include a method using an acidic aqueous solution.
The type of acid used in the acidic aqueous solution is not particularly limited, but is not limited to inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid and phosphoric acid, carboxylic acids such as formic acid, acetic acid and propionic acid, oxalic acid, malonic acid and the like. Dicarboxylic acid and the like can be used. Of these, sulfuric acid, nitric acid and hydrochloric acid are preferable.

The acid concentration of the acidic aqueous solution is not particularly limited, but is usually 0.01 M or more, preferably 0.1 M or more, more preferably 1 M or more, usually 10 M or less, and preferably 8 M or less. It is more preferably 6M or less. By setting the acid concentration in the above range, it is preferable that the total acid amount can be efficiently reduced in a short treatment time without causing the collapse of the skeletal structure.

The amount of the acidic aqueous solution for zeolite is not particularly limited, but the total amount of the acidic aqueous solution is usually 3 g or more, preferably 5 g or more, more preferably 10 g or more, and usually 100 g or less, with respect to 1 g of zeolite. It is preferably 80 g or less, more preferably 50 g or less. By setting the amount of the acidic aqueous solution in the above range, it is preferable in that sufficient stirring efficiency of the slurry can be obtained and a certain productivity can be ensured.

The temperature of the acid treatment is not particularly limited, but it can be carried out at normal pressure from room temperature to 100 ° C. and in a pressure resistant container at 100 ° C. or higher, and is usually 40 ° C. or higher, preferably 60 ° C. or higher. , More preferably 80 ° C. or higher, usually 200 ° C. or lower, preferably 180 ° C. or lower, more preferably 160 ° C. or lower. By setting the acid treatment temperature within the above range, it is preferable that the total acid amount can be efficiently reduced in a short treatment time while suppressing the collapse of the skeletal structure.

The treatment time of the acid treatment is not particularly limited and depends on the acid concentration and the reaction temperature, but is usually 0.01 hours or more, preferably 0.1 hours or more, as long as the performance of the catalyst is not impaired. There is no particular upper limit to the processing time. The treatment time can be appropriately adjusted depending on the acid concentration and the reaction temperature.
By adding a silylating agent to the acidic aqueous solution, the acid treatment and the silylation treatment can be performed at the same time. The silylating agent used at that time is the same as the silylating agent.

<Ion exchange processing>
The counter cation of zeolite is usually an alkali metal such as sodium, an alkaline earth metal, ammonium (NH ₄ ) or a proton (H). These counter cations are ion-exchangeable and can be used by appropriately exchanging metal ions.
Examples of the metal to be exchanged include, but are not limited to, alkali metals such as lithium, sodium, potassium, rubidium and cesium, and alkaline earth metals such as magnesium, calcium, strontium and barium. It is preferably sodium, potassium, magnesium and calcium, more preferably sodium, potassium and calcium, and even more preferably calcium.

By ion exchange, the acid amount of zeolite can be adjusted, and further, the cage space volume can be adjusted, so that coke accumulation during the reaction can be suppressed. It is also preferable in that the thermal / hydrothermal stability is high and deterioration can be suppressed. The method of metal ion exchange is not particularly limited, but can be performed by a known ion exchange method. The cation of zeolite when used in the ion exchange method is not particularly limited, and a sodium type, an ammonium type, or a proton type is usually used.

As the metal source, nitrates, sulfates, acetates, carbonates, chloride salts, bromide salts, iodide salts and the like are usually used, preferably nitrates, sulfates and chloride salts, and more preferably nitrates. Is.
The solvent used is not particularly limited as long as it dissolves the metal source, but water is usually used.

The concentration of the metal source solution is not particularly limited, but is usually 0.1 M or more, preferably 0.5 M or more, more preferably 1 M or more, and the upper limit is usually 10 M or less, preferably 8 M or less. More preferably, it is 6 M or less. It is desirable to adjust the concentration according to the solubility of the metal source.

The temperature at which ion exchange is performed is from room temperature to about the boiling point of the solvent. The treatment time may be any time as long as the ion exchange reaches a sufficient equilibrium, and is usually about 1 to 6 hours. It is also possible to repeat ion exchange multiple times in order to increase the metal exchange rate.

Separation of the zeolite from the suspension treated for a predetermined time is carried out by a usual solid-liquid separation operation, for example filtration or centrifugation.

The atmosphere for drying the zeolite after ion exchange is not particularly limited, and the atmosphere is, for example, in air, in an inert gas, in vacuum, or the like. The drying temperature is usually from room temperature to about the boiling point of the solvent.

Zeolites after ion exchange are appropriately calcined before use. The firing temperature may be higher than the decomposition temperature of the metal source, and is usually 200 ° C. to 600 ° C., preferably 300 ° C. to 500 ° C. If the calcination temperature is too low, the metal source tends to remain, and if the calcination temperature is too high, the structure of zeolite is likely to collapse and metal synterling is likely to proceed.

In addition to the above, the amount of outer surface acid can also be adjusted by a method such as carrying a metal element or binding the binder and the outer surface acid point of the zeolite when forming the zeolite.

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, and usually 10 μm or less, preferably 5 μm. Below, it is more preferably 2 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 hydrothermal 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 primary particle size is arbitrarily 20 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"). It is measured and obtained by averaging the particle diameters of the primary particles. When the particle is rectangular, the long and short sides of the particle are measured (depth is not measured), and the average of the sum, that is, (long side + short side) / 2, is calculated to obtain the particle. The primary particle size.

(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 / p0 = 0.30).

The pore volume of the zeolite of the present invention is not particularly limited, but is usually 0.1 ml / g or more, preferably 0.2 ml / g or more, and usually 3 ml / g or less, preferably 2 ml / g or less. Is. 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 pore volume is preferably a value obtained from the adsorption isotherm of nitrogen obtained by the relative pressure method.

The zeolite of the present invention can generally be prepared by a hydrothermal synthesis method. For example, in the case of silicate, at least one selected from an aluminum source, a gallium source, a boron source, and an iron source, a silicon source, an alkaline aqueous solution, etc. are added to water to generate a uniform gel, which is necessary. Add a structure-defining agent and stir to prepare a raw material gel. The obtained raw material gel is heated in a closed container and reacted under self-pressure to crystallize it. The reaction temperature at this time is not particularly limited, but is usually kept at 100 to 200 ° C. for crystallization. A seed crystal may be added at the time of crystallization as needed, and it is preferable to add the seed crystal in terms of manufacturability because the reaction time can be shortened and the crystal particles can be made into fine particles. Then, after filtering and washing the crystallized solid component, the solid content is dried and subsequently calcined to obtain an alkaline (earth) metal type zeolite. The drying temperature is not limited, but is usually 100 to 200 ° C. The firing temperature is not limited, but is usually 400 to 700 ° C. Then, H-type zeolite can be obtained by ion exchange with an acidic solution or an ammonium salt solution and firing.

Specifically, the CHA-type zeolite can be produced by a known method such as the method described in US Pat. No. 4,544,538. Further, the ERI type zeolite can be produced by a known method such as the method described in US Pat. No. 7,344,694.

The cation used as the structure defining agent is accompanied by an anion that does not inhibit the formation of the zeolite of the present invention. The anion is not particularly limited, but specifically includes halogen ions such as Cl-, Br-, and I-, hydroxide ions, acetates, sulfates, and carboxylates. Among them, hydroxide ion is particularly preferably used.

Further, as the structure-determining agent, a phosphorus-containing structure-determining agent or a nitrogen-based structure-determining agent can also be used. Examples of the phosphorus-containing structure-determining agent include substances such as tetraethylphosphonium hydroxide and tetraethylphosphonium bromide. However, the phosphorus compound is preferably a nitrogen-based structure-determining agent because it may generate diphosphorus pentoxide or the like, which is a harmful substance, when the structure-determining agent is removed from the synthetic zeolite by firing.

After hydrothermal synthesis and calcination, it is preferable that the obtained zeolite is appropriately subjected to at least one treatment selected from silylation treatment, steam treatment, heat treatment, acid treatment and ion exchange as described above. Of these, at least one treatment selected from silylation treatment, steam treatment, heat treatment, and ion exchange is preferably performed, and more preferably, at least one treatment selected from silylation treatment, steam treatment, and ion exchange is performed. It has been subjected to at least one treatment selected from silylation treatment and steam treatment, and more preferably has been subjected to silylation treatment.

Since zeolite is a catalytically active component, zeolite may be used as it is as a zeolite catalyst in the reaction, or it may be granulated and molded using a substance or binder that is inert to the reaction, or these may be mixed and used in the reaction. You may use it.
Examples of the substance or binder inert to the reaction include alumina or alumina sol, silica, silica sol, quartz, and a mixture thereof.

The total acid amount and the outer surface acid amount of the zeolite catalyst can be measured by the same method as the above-mentioned total acid amount and outer surface acid amount of the zeolite. The total acid amount of the zeolite catalyst is not particularly limited, but is usually 0.01 mmol / g or more, preferably 0.10 mmol / g or more, more preferably 0.20 mmol / g or more, still more preferably 0.30 mmol or more. / G or more. Further, it is usually 2.0 mmol / g or less, preferably 1.5 mmol / g or less, more preferably 1.0 mmol / g or less, still more preferably 0.80 mmol / g or less. By setting the total acid amount of the zeolite catalyst in the above range, the conversion activity of methanol 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 zeolite catalyst is not particularly limited, but is usually 8% or less, preferably 5% or less, more preferably 3% or less, still more preferably 1%, based on the total acid amount of the catalyst. Hereinafter, it is 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.
In order to adjust the total acid amount and the outer surface acid amount of the zeolite catalyst, it is preferable to use it as a binder such as silica or alumina having no acid point.
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 value including the acid amount of the zeolite and the acid amount of the binder is measured. To. 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.

The average particle size of the zeolite catalyst varies depending on the synthesis conditions of the 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 average particle size of the zeolite catalyst is 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.

<2. Method for producing lower olefin>
As described above, lower olefins can be produced by contacting a raw material containing methanol and / or dimethyl ether with a zeolite catalyst. In the present invention, the lower olefin means an olefin having 2 or more and 4 or less carbon atoms. The present invention is a method suitable for ethylene production and propylene production, and is particularly suitable for ethylene production.

The origin of production of methanol and dimethyl ether as raw materials is not particularly limited. For example, those obtained by hydrogenation reaction of CO / hydrogen mixed gas derived from coal and natural gas and by-products in the iron manufacturing industry, those obtained by reforming reaction of alcohols derived from plants, and those obtained by fermentation method. , Recirculated plastics, those obtained from organic substances such as municipal waste, etc. 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.

The reactor used for producing the lower olefin is not particularly limited as long as the methanol and / or dimethyl ether feedstock is a gas phase in the reaction region, but a fixed bed reactor, a moving bed reactor or a fluidized bed reactor is selected. When ethylene, propylene, and butenes are co-produced, the selectivity of each lower olefin tends to fluctuate as the conversion rate fluctuates. Therefore, in order to produce each lower olefin at a constant ratio, a fluidized bed is used. A reactor is preferred.
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, in order to keep the temperature distribution of the catalyst layer small, particles that are inert to the reaction such as quartz sand, alumina, silica, and silica-alumina are mixed with the catalyst. And fill. 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)
The total concentration (substrate concentration) of methanol and dimethyl ether in all the supply components supplied to the reactor is not particularly limited, but the sum of methanol and dimethyl ether is usually 5 mol% or more, preferably 10 mol, in all the supply components. % Or more, more preferably 20 mol% or more, still more preferably 30 mol% or more, particularly preferably 50 mol% or more, usually 95 mol% or less, preferably 90 mol% or less, more preferably 70 mol% or less. be. 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.

The total ratio of methanol and dimethyl ether in the raw material containing methanol and / or dimethyl ether supplied to the reactor is not particularly limited, but is usually 10% by mass or more, preferably 30% by mass or more, and more preferably 50% by mass. % Or more, more preferably 80% by mass or more, and the upper limit is 100% by mass. By setting the above ratio in the above range, the carbon introduction rate from the raw material methanol and / or dimethyl ether into the lower olefin becomes high, and when inexpensive methanol or dimethyl ether is used, the lower olefin can be produced inexpensively. Can be done.

(Diluent)
In the reactor, in addition to methanol and / or dimethyl ether, hydrocarbons such as helium, argon, nitrogen, carbon monoxide, carbon dioxide, hydrogen, water, paraffins, methane, aromatic compounds, and them. A gas inert to the reaction can be present, such as a mixture of the above, but it is preferable that helium, nitrogen, and water (water vapor) 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 as the diluent, 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 methanol and / or dimethyl ether which is a reaction raw material per weight of the catalyst (catalyst active component), and the weight of the catalyst is not used for granulation / molding of the catalyst. The weight of the catalytically active ingredient without the active ingredient or binder. The flow rate is the total flow rate (weight / hour) of methanol and / or dimethyl ether.

The weight space velocity is not particularly limited, but is usually 0.01 Hr ^-1 or more, preferably 0.1 Hr ^-1 or more, more preferably 0.2 Hr ^-1 or more, still more preferably 0.5 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 methanol and / or dimethyl ether in the reactor outlet gas can be reduced, and by-products such as aromatic compounds and paraffins can be reduced. Therefore, 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 methanol and / or dimethyl ether comes into contact with the catalyst to form a lower olefin, but is usually 250 ° C. or higher, preferably 300 ° C. or higher, more preferably 325 ° C. As described above, it is more preferably 350 ° C. or higher, usually 600 ° C. or lower, preferably 550 ° C. or lower, more preferably 500 ° C. or lower, still more preferably 450 ° 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 methanol and / or dimethyl ether can be maintained at a high level, it can be produced in a high lower olefin yield over a long period of time. Further, when the zeolite is a silicate, dealumination from the zeolite skeleton is suppressed, which 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, particularly preferably 0.4 MPa or less, and most preferably 0.3 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 methanol and dimethyl ether is not particularly limited, but is usually 0.005 MPa or more (absolute pressure, the same applies hereinafter), preferably 0.01 MPa or more, more preferably 0.02 MPa or more, still more preferably 0. It is 0.03 MPa or more, particularly preferably 0.05 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, and particularly preferably 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.

(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. According to the present invention, 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, and the yield of lower olefins can be increased. Can be improved. In addition, the separation efficiency of methanol and / or dimethyl ether from the product can be enhanced.

Usually, the accumulation of cork progresses with the lapse of the reaction time, and the conversion rate of methanol and / or dimethyl ether 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.

(Hydrocarbon component)
By conversion of methanol and / or dimethyl ether, a part of it is on the inner / outer surface of the crystal, a lightly boiling hydrocarbon component that can be recovered by stripping treatment, and coke (polycyclic aromatics, etc.) that needs to be removed by regeneration treatment. Accumulates as a quality component). If the hydrocarbon content (total content of light boiling hydrocarbon component and cork) with respect to zeolite, which is the active component of the zeolite catalyst, increases too much during the reaction, the catalytic activity tends to decrease. Therefore, during the reaction, the ratio of the hydrocarbon content to the zeolite, which is the active component of the zeolite catalyst, is preferably kept at 30% by mass or less, more preferably 25% by mass or less, and kept at 20% by mass or less. It is more preferable, and it is particularly preferable to keep it at 15% by mass or less. That is, when the hydrocarbon content of the zeolite catalyst with respect to zeolite becomes larger than the above range, it is preferable to perform the zeolite catalyst treatment step described later on the zeolite catalyst. The ratio of the hydrocarbon content to the zeolite can be adjusted by the regeneration treatment of the zeolite catalyst, which will be described later. On the other hand, in order to suppress the by-product of paraffins and improve the yield of the lower olefin while maintaining the conversion activity of methanol and / or dimethyl ether, the ratio of the hydrocarbon content to the zeolite is 0.1% by mass. It is preferable to keep it at the above, it is more preferable to keep it at 3.0% by mass or more, and it is particularly preferable to keep it at 5.0% by mass or more.

The hydrocarbon content here can be determined by thermogravimetric analysis (TG). Specifically, the zeolite in which the hydrocarbon component is accumulated by the conversion reaction of methanol and / or dimethyl ether is heated to 200 ° C. at a heating rate of 10 ° C./min under the flow of an inert gas such as helium (50 cc / min). , The adsorbed water is removed by holding for 30 minutes. Subsequently, the system is switched to air flow (50 cc / min), heated to 600 ° C. at a heating rate of 10 ° C./min, and held for 60 minutes. The weight reduction due to oxidative combustion in the temperature range of 200 ° C. or higher at this time is defined as the hydrocarbon content.

The content of the cork (cork content) is preferably 25% by mass or less with respect to the zeolite which is the active component of the zeolite catalyst in order to obtain an appropriate catalytic activity and a high lower olefin selectivity. , 20% by mass or less, more preferably 15% by mass or less, further preferably 0.1% by mass or more, still more preferably 1.0% by mass or more, 3 It is particularly preferable to keep it at 0.0% by mass or more.
The coke content is such that the zeolite in which coke has accumulated due to the conversion reaction of methanol and / or dimethyl ether is heated to 550 ° C. at a heating rate of 10 ° C./min under the flow of an inert gas such as helium (50 cc / min). By holding for 30 minutes, the adsorbed water and the light boiling hydrocarbon component are removed. Subsequently, the system is switched to air flow (50 cc / min), heated to 600 ° C. at a heating rate of 10 ° C./min, and held for 60 minutes. The weight loss due to oxidative combustion in the temperature range of 550 ° C. or higher at this time is defined as the cork content.

(Reaction product)
As the reactor outlet gas (reactor effluent), a mixed gas containing reaction products such as lower olefins of ethylene, propylene and butenes, 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, methanol and / or dimethyl ether is contained as an unreacted raw material in the reaction product, but it is preferable to carry out the reaction under reaction conditions such that the conversion rate of methanol and / or dimethyl ether becomes 100%. 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. The residue obtained by separating and recovering the desired component contains light paraffin, C5 or higher olefin, aromatic compound, steam and the like. 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.

In the present invention, 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 particularly high. Not limited, but 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.

Among the lower olefins, the ratio of straight-chain butenes of butenes (hereinafter, linear butenes / butenes) is not particularly limited, but is usually 60% or more, preferably 80% or more, more preferably. It is 90% or more, and most preferably 100%. When the ratio of linear butene / butenes is in the above range, it is preferable in that the load in the separation / purification step of linear butene can be reduced.

The conversion rate is a value calculated by the following formula.
Methanol conversion rate (%) = [[reactor inlet methanol (mol / Hr) -reactor outlet methanol (mol / Hr)] / reactor inlet methanol (mol / Hr)] × 100
Dimethyl ether conversion rate (%) = [[Reactor inlet dimethyl ether (mol / Hr) -Reactor outlet dimethyl ether (mol / Hr) -Reactor outlet methanol (mol / Hr)
÷ 2] / Reactor inlet dimethyl ether (mol / Hr)] × 100

The selectivity in the present specification is a value calculated by each of the following formulas. In each of the following formulas, the "derived carbon flow rate (mol / Hr)" of hydrocarbons such as ethylene, propylene, butene, C5 +, paraffin and aromatic compounds means the molar flow rate of carbon atoms constituting each hydrocarbon. do. When dimethyl ether is used as the raw material, it is calculated by using the total carbon molar flow rate of dimethyl ether and methanol for the carbon molar flow rate derived from the reactor outlet raw material of the following formula.
Paraffin is the total of paraffin having 1 to 4 carbon atoms, aromatic compound is the total of benzene, toluene and xylene, and C5 + is the total of hydrocarbons having 5 or more carbon atoms excluding the aromatic compound.
Ethylene selectivity (%) = [reactor outlet ethylene-derived carbon molar flow rate (mol / Hr) / [reactor outlet total carbon molar flow rate (mol / Hr) -reactor outlet methanol-derived carbon molar flow rate (mol / Hr)) ]] × 100
Propene selectivity (%) = [reactor outlet propylene-derived carbon molar flow rate (mol / Hr) / [reactor outlet total carbon molar flow rate (mol / Hr) -reactor outlet methanol-derived carbon molar flow rate (mol / Hr)) ]] × 100
Buten selectivity (%) = [reactor outlet butene-derived carbon molar flow rate (mol / Hr) / [reactor outlet total carbon molar flow rate (mol / Hr) -reactor outlet methanol-derived carbon molar flow rate (mol / Hr)) ]] × 100
C5 + selectivity (%) = [reactor outlet C5 + derived carbon molar flow rate (mol / Hr) / [reactor outlet total carbon molar flow rate (mol / Hr) -reactor outlet methanol derived carbon molar flow rate (mol / Hr)) ]] × 100
• Paraffin selectivity (%) = [reactor outlet paraffin-derived carbon molar flow rate (mol / Hr) / [reactor outlet total carbon molar flow rate (mol / Hr) -reactor outlet methanol-derived carbon molar flow rate (mol / Hr)) ]] × 100
Aromatic compound selectivity (%) = [reactor outlet aromatic compound-derived carbon molar flow rate (mol / Hr) / [reactor outlet total carbon molar flow rate (mol / Hr) -reactor outlet methanol-derived carbon molar flow rate (mol / Hr) mol / Hr)]] × 100
Dimethyl ether selectivity (%) = [reactor outlet dimethyl ether-derived carbon molar flow rate (mol / Hr) / [reactor outlet total carbon molar flow rate (mol / Hr) -reactor outlet methanol-derived carbon molar flow rate (mol / Hr)) ]] × 100 (However, use only when methanol is used as the raw material)
The yield in the present specification is determined by the product of the raw material conversion rate and the selectivity of each produced component, and specifically, the ethylene yield, the propylene yield, and the butene yield are as follows. It is represented by.
-Ethylene yield (%) = raw material conversion rate (%) x ethylene selectivity (%) / 100
-Propene yield (%) = raw material conversion rate (%) x propylene selectivity (%) / 100
-Butene yield (%) = raw material conversion rate (%) x linear butene selectivity (%) / 100

(Separation of products)
The mixed gas containing the reaction product lower olefin, unreacted raw material, by-product and diluent as the reactor outlet gas is introduced into a known separation / purification facility, and is recovered and purified according to each component. , Recycle, and discharge processing.

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 a distillation column for distillation.

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. May be recycled. Further, among the by-products, the components inactive for the reaction can be reused as a diluent.

<3. Zeolite catalyst treatment method>
In the method for producing a lower olefin, the hydrocarbon content (content of light boiling hydrocarbon component and cork) in the zeolite catalyst tends to increase with the conversion of the raw material containing methanol and / or dimethyl ether. In particular, when the coke content in the zeolite catalyst increases, the activity of the zeolite catalyst tends to decrease, and the yield of the lower olefin tends to decrease. Therefore, in the present invention, by treating the zeolite catalyst in which the lightly boiling hydrocarbon component and cork are accumulated with a gas containing hydrogen, it is possible to produce a lower olefin in high yield while recovering the catalytic activity. Become.

Conventionally, as a method for regenerating a zeolite catalyst using a gas containing hydrogen, as described in Japanese Patent No. 5545114, in the production of propylene using ethylene as a raw material, coke can be removed to restore the catalytic activity. Has been reported. As the reaction mechanism for producing propylene from an ethylene raw material, a reaction mechanism for hexene production by dimerization of ethylene, subsequent decomposition to produce two propylene molecules, and a mechanism for propylene production from propylnaphthalene have been proposed (Journal of). Catalyst 314 (2014) 10-20). As disclosed here, when ethylene is used as a raw material, highly reactive hexene, naphthalene derivative, or the like is used as an intermediate, so that it is considered that the regeneration treatment with hydrogen gas can be applied. On the other hand, when the method for regenerating a catalyst for producing propylene from ethylene is applied to a catalyst for producing olefin from methanol, a large amount of water is generated when producing olefin from methanol, which is adsorbed on the zeolite active site. It is thought that it inhibits hydrogen regeneration, and that the zeolite itself undergoes structural collapse when exposed to a higher temperature than when olefins are produced from methanol for regeneration of zeolite containing water and methanol. Was considered unsuitable for practical use because the load of the subsequent separation / purification process becomes very large when methanol or water, which is a condensed component, and hydrogen are mixed.

On the other hand, in the case of a reaction for producing a lower olefin from a raw material containing methanol and / or dimethyl ether, a reaction mechanism for producing a polymethylbenzene intermediate has been proposed, although the detailed reaction mechanism is unknown (Chem. Eur. J. 15 (2009) 10803-10808). Normally, the benzene ring is highly aromatic and highly stable, so it is considered difficult to decompose it with a zeolite catalyst that does not contain hydrogenated active metals such as nickel and palladium, and conventional zeolites are considered to be difficult to decompose. In the catalyst regeneration method, combustion regeneration using a gas containing oxygen has been performed.
Furthermore, when methanol and / or dimethyl ether is used as a raw material, a large amount of water is produced as a by-product along with the production of lower olefins, so stripping with a gas with high adsorptive capacity such as water (steam) is effective, and strikes. As the ripping gas, water (water vapor) has been preferably used instead of a gas having a low adsorption capacity such as hydrogen and methane.

In addition, the gas containing the light boiling hydrocarbon component and water (steam) recovered by stripping using water (steam) can be separated and purified by the same process as the product gas, so that the energy cost can be reduced. It is possible and has been preferably used conventionally. On the other hand, when a gas with a low boiling point such as hydrogen or methane is used, the amount of gas of the low boiling point component increases, and the load on the separation / purification system, especially the load on the deep-cooled separation unit, tends to increase. It is not suitably used as a ripping gas.
Therefore, conventionally, in the method for regenerating a zeolite catalyst in a method for producing a lower olefin using methanol and / dimethyl ether as raw materials, a step of regenerating a zeolite catalyst using a gas containing hydrogen as described in Japanese Patent No. 5545114 is applied. However, it was thought that a significant recovery of the catalytic activity of the zeolite catalyst could not be expected.

However, in the present invention, in the reaction for producing a lower olefin from a raw material containing methanol and / or dimethyl ether, the zeolite catalyst having an increased hydrocarbon content is unexpectedly contained in the zeolite catalyst by treating it with a gas containing hydrogen. It has been found that the lightly boiling hydrocarbon component of the above can be effectively stripped, and further, the catalytic activity can be significantly restored by removing cork. In the treatment with a gas containing hydrogen, in addition to the normal stripping recovery, it is possible to regenerate the catalyst with the same gas, so it is possible to incorporate the stripping equipment and the regenerator as the same equipment, and the plant construction cost and It is possible to significantly reduce the production cost of the lower olefin.

The catalyst having an increased hydrocarbon content means a catalyst in which the amount of a hydrocarbon component contained in the catalyst is increased by the reaction in a reaction for producing a lower olefin from a raw material containing methanol and / or dimethyl ether.
Specifically, it contains strippable light boiling hydrocarbons produced by the reaction and coke that needs to be regenerated and removed.

In the treatment method using a gas containing hydrogen, the catalyst is brought into contact with a gas containing hydrogen having an absolute hydrogen partial pressure of 0.01 MPa or more. In this method, the light boiling hydrocarbon component contained in the catalyst can be efficiently recovered, and the yield of the lower olefin can be remarkably restored by removing the cork.

The device for treating with a gas containing hydrogen is not particularly limited as long as the gas containing hydrogen and the catalyst can come into contact with each other under the following conditions, but in the case of a fixed bed, a reactor for producing a lower olefin is used. A method of flowing a gas containing hydrogen without extracting the catalyst from the catalyst is preferably used. Further, the catalyst may be removed from the reactor, filled in a reactor different from the reactor, and then brought into contact with hydrogen gas for regeneration.

In the case of a moving bed or a fluidized bed, a device for contacting a gas containing hydrogen with a catalyst is provided separately from the reactor, and the catalyst extracted from the reactor is continuously sent to the device in the device. It is preferable to treat with hydrogen gas and then carry out the reaction while continuously returning the catalyst to the reactor. That is, the step of transferring the zeolite catalyst that has undergone the reaction to generate the lower olefin stored in the reactor to the hydrogen-containing gas flow device attached to the reactor, the zeolite catalyst and the gas containing hydrogen in the flow device. It is preferable to include a step of contacting and a step of transferring the zeolite catalyst brought into contact with a gas containing hydrogen to the reactor and subjecting it to a reaction for producing a lower olefin.

The pressure when contacting with a gas containing hydrogen 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 preferable. Is 0.2 MPa or more, 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, particularly preferably 0.4 MPa or less, and most preferably 0.3 MPa or less. ..
As described above, the hydrogen-containing gas has a hydrogen partial pressure of 0.01 MPa or more in absolute pressure, preferably 0.03 MPa or more, more preferably 0.05 MPa or more, still more preferably 0.10 MPa or more. Usually, 4 MPa or less is preferable, 1 MPa or less is more preferable, 0.7 MPa or less is further preferable, 0.4 MPa or less is particularly preferable, and 0.3 MPa or less is most preferable. By setting the hydrogen partial pressure within the above range, the light boiling hydrocarbon component inside the zeolite pores can be efficiently stripped, and coke can be efficiently removed by hydrocracking. , Equipment and energy for producing high-pressure hydrogen can be reduced.

The method for producing hydrogen contained in the hydrogen-containing gas of the present invention is not particularly limited, and for example, those obtained by steam reforming of methane and methanol, those obtained by partial oxidation of hydrocarbons, and hydrocarbons using carbon dioxide. What is obtained by reforming, what is obtained by gasification of coal, what is obtained by thermal decomposition of water represented by IS (Idine-Sulfur) process, what is obtained by photoelectrochemical reaction, and electricity of water. Any of those obtained by various manufacturing methods, such as those obtained by decomposition, can be used.

A gas other than hydrogen may be arbitrarily mixed, or purified hydrogen may be used.

As the gas other than hydrogen, for example, hydrocarbons such as helium, argon, nitrogen, oxygen, carbon monoxide, carbon dioxide, paraffins, and methane may be contained. Of these, helium, nitrogen, carbon dioxide, paraffins, and methane are preferable because of their low reactivity.

The gas after being used for treatment with a gas containing hydrogen contains water and hydrocarbon components (olefins, paraffins, etc.) in addition to hydrogen, but these may be recycled as they are, or other than hydrogen. Gas may be partially or completely removed and used for recycling.

The space velocity of the gas containing hydrogen is not particularly limited, but is usually 0.001 Hr ^-1 or more, preferably 0.01 Hr ^-1 or more, more preferably 0.1 Hr ^-1 or more, and usually 20 Hr ⁻ . It is ¹ or less, preferably 10 Hr ^-1 or less, more preferably 5 Hr ^-1 or less, still more preferably 0.1 Hr ^-1 or less. By setting the weight space velocity within the above range, it is possible to suppress the separation and purification load of the light boiling hydrocarbon component recovered by hydrogen treatment. Moreover, since the amount of hydrogen gas used can be suppressed, the manufacturing cost can be reduced.

By setting the space velocity within the above range, an increase in the concentration of the light boiling hydrocarbon component stripped from the catalyst in the gas containing hydrogen is suppressed, and a high lower olefin yield can be obtained in the reaction after regeneration. preferable. Moreover, since the amount of hydrogen used can be suppressed, the process cost can be reduced.

The space velocity is the flow rate of hydrogen per weight of the catalyst (catalytic active ingredient). The weight of the catalyst is the weight of the active ingredient (zeolite) that does not contain the inert component or binder used for granulation / molding of the catalyst.

The hydrogen concentration in the gas containing hydrogen is not particularly limited, but is usually 10% by volume or more, preferably 30% by volume or more, more preferably 50% by volume or more, still more preferably 80% by volume or more. , Usually 100% by volume or less. Within the above range, the hydrocracking of cork can be efficiently promoted.

The temperature at which the treatment with a gas containing hydrogen (hereinafter, may be referred to as “hydrogen treatment temperature”) is not particularly limited, but is usually 250 ° C. or higher, preferably 350 ° C. or higher, more preferably 400 ° C. or higher. ° C. or higher, more preferably 450 ° C. or higher, particularly preferably 500 ° C. or higher, usually 800 ° C. or lower, preferably 700 ° C. or lower, more preferably 650 ° C. or lower, still more preferably 600 ° C. or lower. By setting the hydrogen treatment temperature within the above range, the adsorption ability of the lightly boiling hydrocarbon component in the pores is lowered and the diffusibility is improved, so that the stripping effect can be easily obtained. At the same time, it becomes easier to remove cork by hydrocracking.

The time for processing with a gas containing hydrogen is not particularly limited, but is usually 10 seconds or longer, preferably 1 minute or longer, more preferably 5 minutes or longer, and usually 5 hours or shorter, preferably 2 hours. Hereinafter, it is more preferably 1 hour or less. Since the appropriate time varies depending on the concentration of hydrogen gas and the treatment temperature, it is preferable to adjust the appropriate time. When the device that performs the treatment with the gas containing hydrogen is a fluidized bed device, the above-mentioned treatment time means the residence time of the catalyst in the device.

The rate of change in the hydrocarbon content (total of light boiling hydrocarbon components and cork content) in the catalyst before and after treatment with a gas containing hydrogen is not particularly limited, but is usually 60%. Below, it is preferably 40% or less, more preferably 30% or less, still more preferably 20% or less, usually 0.1% or more, preferably 1% or more, more preferably 5% or more, still more preferably 10% or more. Is. By setting the rate of change in the hydrocarbon content within the above range, each lower olefin can be stably produced at a constant rate over a long period of time, which is preferable.
The rate of change in the hydrocarbon content is a value calculated by each of the following equations.

Rate of change in hydrocarbon content (%) = [Hydrocarbon content before hydrogen treatment (% by mass) -Hydrocarbon content after hydrogen treatment (% by mass)] / Hydrocarbon content before hydrogen treatment (% by mass) ) × 100

The rate of change in the coke content in the zeolite catalyst before and after treatment with a gas containing hydrogen is not particularly limited, but is usually 60% or less, preferably 40% or less, more preferably 30. % Or less, more preferably 20% or less, usually 0.1% or more, preferably 1% or more, more preferably 5% or more, still more preferably 10% or more. By setting the rate of change in the cork content within the above range, each lower olefin can be stably produced at a constant rate over a long period of time, which is preferable.
The rate of change in the cork content is a value calculated by each of the following equations.

Rate of change in cork content (%) = [Cork content before hydrogen treatment (% by mass) -Cork content after hydrogen treatment (% by mass)] / Cork content before hydrogen treatment (% by mass) x 100

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.

<Catalyst Preparation Example 1>
0.79 g of potassium hydroxide (manufactured by Kishida Chemical) and 1.4 g of hexamethonium bromide (manufactured by Tokyo Chemical Industry) were dissolved in 10.7 g of water in this order, and HY-type zeolite (SiO ₂ / Al ₂ O ₃ ratio) was dissolved. 10. Tosoh HSZ-350HUA) 2.9 g was added. Further, 0.048 g of CHA-type zeolite (SiO ₂ / Al ₂ O3 ratio 25, _average primary particle diameter of about 200 nm) was added as a seed crystal to the added SiO ₂ , and the mixture was further stirred to prepare the mixture. Obtained. The mixture was placed in a 100 ml autoclave and subjected to a hydrothermal synthesis reaction at 180 ° C. for 1 day while rotating at 15 rpm under its own pressure. The obtained product was filtered, washed with water, and dried at 100 ° C. to obtain 3.3 g of a white powder. From the XRD pattern of the product, it was confirmed that the obtained product was in the ERI phase. From ICP elemental analysis, the SiO ₂ / Al ₂ O ₃ ratio was 10.0. The ERI-type zeolite (zeolite before calcination) obtained by hydrothermal synthesis was calcined at 580 ° C. for 6 hours under air flow to obtain a K-containing ERI-type zeolite (catalyst 1).

<Catalyst preparation example 2>
2.09 g of sodium hydroxide (Kishida Chemical Co., Ltd.) and 47.3 g of 25% by weight N, N, N-trimethyl-1-adamantanamium ammonium hydroxyside aqueous solution (Seichem, 25% by mass) were sequentially added to 89.6 g of water. Then, 4.27 g of aluminum hydroxide (manufactured by Aldrich, 50 to 57% by weight in terms of aluminum oxide) was added and mixed, and then colloidal silica SI-30 (SiO ₂ 30% by weight, Na 0. 3% by weight (manufactured by JGC Catalysts and Chemicals) 111 g was added and stirred sufficiently. Further, 10% by weight of CHA-type zeolite (SiO ₂ / Al ₂ O3 ratio 25, _average primary particle diameter of about 200 nm) was added as a seed crystal with respect to the added SiO ₂ , and the mixture was further stirred. Next, this gel was placed in a 1000 ml autoclave, and hydrothermal synthesis was carried out at 160 ° C. for 20 hours while stirring at 250 rpm under self-pressure. The product was filtered, washed with water and then dried. From the XRD pattern of the product, it was confirmed that the obtained product was in the CHA phase. From XRF analysis, the SiO ₂ / Al ₂ O ₃ ratio was 22.
The CHA-type zeolite (zeolite before calcination) obtained by hydrothermal synthesis was calcined at 580 ° C. for 6 hours under air flow to obtain a Na-containing CHA-type zeolite. Next, ion exchange was carried out twice at 80 ° C. for 1 hour with a 1 M aqueous ammonium nitrate solution, dried at 100 ° C., and then fired at 500 ° C. for 6 hours under air flow to obtain a proton-type CHA-type zeolite.
Next, 20 ml of toluene as a solvent and 5 ml of tetraethoxysilane as a silylating agent were added to 2.0 g of the proton-type CHA-type zeolite, and heat treatment was performed at 70 ° C. for 4 hours with stirring. After completion of the reaction, the solid and liquid were separated by filtration and the solid content was dried at 100 ° C. to obtain a silylated proton-type CHA-type zeolite (catalyst 2).

<Catalyst Preparation Example 3>
The catalyst 2 is steam-treated and silylated by a proton-type CHA type by treating the catalyst 2 at 650 ° C. under normal pressure under 50% steam (steam / air = 50/50 (volume / volume)) flow for 5 hours. Zeolites were obtained (catalyst 3).

<Example 1>
Using the catalyst 1, a reaction for synthesizing a lower olefin using methanol as a raw material was carried out. For the reaction, a normal pressure fixed bed flow reactor was used, and a quartz reaction tube having an inner diameter of 6 mm was filled with a mixture of 200 mg of the catalyst and 300 mg of quartz sand. Methanol and nitrogen were supplied to the reactor so that the weight space velocity of methanol was 0.25 Hr ^-1 and the volume was 30% by volume of methanol and 70% by volume of nitrogen, and the lower olefin was supplied at 350 ° C. and 0.1 MPa (absolute pressure). The synthetic reaction of the above was carried out, and the reactor outlet gas was analyzed by gas chromatography. Table 1 shows the reaction results 12.1 hours after the start of the reaction and the hydrocarbon content in the zeolite catalyst.
With respect to the hydrocarbon-containing catalyst after completion of the above reaction, 100% by volume of hydrogen gas was supplied to the reactor so that the space velocity of hydrogen was 100 mmol / (g-zeo · hr) based on the zeolite mass, and the temperature was 500 ° C. , 0.1 MPa (absolute pressure) for 1.0 hour. The hydrocarbon content in the catalyst after the treatment is shown in Table 1. Then, using the catalyst after the hydrogen treatment, the lower olefin synthesis reaction was carried out again under the above reaction conditions. The reaction results are shown in Table 1.
The hydrocarbon content contained in the catalyst was separately measured by the following method by performing the same reaction operation as described above. Under helium gas flow (50 cc / min), heat up to 200 ° C. at a heating rate of 10 ° C./min, hold for 30 minutes, switch to air flow (50 cc / min), and heat up to 600 ° C. at a temperature rise rate of 10 ° C./min. The content of the hydrocarbon was defined as the weight loss due to oxidative combustion in the temperature range of 200 ° C. or higher.
Hydrocarbon content = (weight loss in the temperature range of 200 ° C or higher ÷ amount of filled zeolite) x 100

As shown in Table 1, the methanol conversion rate after 12.1 hours of the lower olefin synthesis reaction was 88.6%, the yield of the lower olefin was 37.7%, and the hydrocarbon content in the catalyst was 22.2% by mass. .. Subsequent hydrogen treatment reduced the hydrocarbon content in the catalyst to 15.0% by weight. In the lower olefin synthesis reaction after the hydrogen treatment, the methanol conversion rate after 2.1 hours was 99.7%, and the yield of the lower olefin was 75.9%. The maximum yield of lower olefins after hydrogen treatment was 75.9% (the highest value before hydrogen treatment was 79.9%).

<Example 2>
Except for using the catalyst 2 instead of the catalyst 1, the same operation as in Example 1 was carried out, the lower olefin synthesis reaction was carried out, the reaction results 9.6 hours after the start of the reaction, and the hydrocarbon content in the catalyst. Is shown in Table 1. The same operation as in Example 1 was carried out on the hydrocarbon-containing catalyst after the reaction was completed, and hydrogen gas treatment and a lower olefin synthesis reaction were carried out. The reaction results are shown in Table 1.

As shown in Table 1, the methanol conversion rate after 9.6 hours of the lower olefin synthesis reaction was 31.3%, the yield of the lower olefin was 24.5%, and the hydrocarbon content in the catalyst was 23.3% by mass. .. Subsequent hydrogen treatment reduced the hydrocarbon content in the catalyst to 16.5% by weight. In the lower olefin synthesis reaction after the hydrogen treatment, the methanol conversion rate after 2.1 hours was 100.0%, and the yield of the lower olefin was 84.6%. The highest value of the lower olefin yield after the hydrogen treatment was 93.8% (the highest value before the hydrogen treatment was 93.3%).

<Example 3>
Using the catalyst 3, a reaction for synthesizing a lower olefin using methanol as a raw material was carried out. For the reaction, a normal pressure fixed bed flow reactor was used, and a quartz reaction tube having an inner diameter of 6 mm was filled with a mixture of 200 mg of the catalyst and 300 mg of quartz sand. Methanol and nitrogen were supplied to the reactor so that the weight space velocity of methanol was 0.50 Hr ^-1 , and the ratio was 50% by volume of methanol and 50% by volume of nitrogen, and the lower olefin was supplied at 400 ° C. and 0.1 MPa (absolute pressure). The synthetic reaction of was carried out. In the catalyst regeneration, 100% by volume of hydrogen gas is supplied to the reactor so that the space velocity of hydrogen is 100 mmol / (g-zeo · hr) based on the zeolite mass with respect to the hydrocarbon-containing catalyst after the reaction is completed. , 500 ° C., 0.1 MPa (absolute pressure) for 1.0 hour. Table 2 shows the reaction results in which the reaction step and the hydrogen regeneration step were repeatedly carried out.

<Comparative Example 1>
Under the reaction conditions of Example 2, the same operation as in Example 2 was carried out except that nitrogen was used as the regeneration treatment gas. The reaction results are shown in Table 3.

From the results of Examples 1 and 2 above, the light boiling hydrocarbon component in the zeolite catalyst can be efficiently stripped by treating the catalyst with a reduced lower olefin yield with hydrogen gas. Furthermore, it is clear that the removal of the cork component can significantly restore the lower olefin yield from 37.7% to 75.9% in Example 1 and from 24.5% to 84.6% in Example 2. It became. It was also confirmed that the maximum yield of lower olefins was at the same level before and after hydrogen treatment. Further, from Example 3, it was clarified that the catalyst regeneration by hydrogen treatment can be repeatedly applied and the yield of the lower olefin can be maintained at a high level.

In the present invention, in a reaction for synthesizing a lower olefin from a raw material containing methanol, a catalyst having a high hydrocarbon content and a reduced yield of a lower olefin is appropriately treated with hydrogen gas to carry out hydrocarbons in the catalyst. It is useful in the industrialization process because the content can be reduced, the catalytic activity in the reaction for synthesizing lower olefins from raw materials containing hydrogen can be restored, and the yield of lower olefins can be maintained at a high level. Is.

Claims (7)

Includes a step of contacting a zeolite catalyst, which has undergone a reaction of producing a lower olefin by contacting a raw material containing methanol and / or dimethyl ether with a zeolite catalyst, with a gas containing hydrogen having an absolute hydrogen partial pressure of 0.01 MPa or more. A method for treating a zeolite catalyst, wherein the amount of acid on the outer surface of the zeolite constituting the zeolite catalyst is 8% or less with respect to the total amount of acid of the zeolite . The method for treating a zeolite catalyst according to claim 1, wherein the zeolite constituting the zeolite catalyst is an oxygen 8-membered ring-structured zeolite. The method for treating a zeolite catalyst according to claim 1 or 2, wherein the zeolite constituting the zeolite catalyst contains d6r, which is defined as a composite building unit by the International Zeolite Association (IZA), in the skeleton. The method for treating a zeolite catalyst according to any one of claims 1 to 3, wherein the zeolite constituting the zeolite catalyst is an aluminosilicate. The zeolite that constitutes the zeolite catalyst is the International Zeolite Association (
The method for treating a zeolite catalyst according to any one of claims 1 to 4, which is a zeolite having a code specified in IZA) and is CHA or ERI. The method for treating a zeolite catalyst according to any one of claims 1 to 5 , wherein the contact temperature is 250 ° C. or higher and 800 ° C. or lower in the step of contacting with the gas containing hydrogen. A step for producing a lower olefin, comprising a step of bringing a raw material containing methanol and / or dimethyl ether into contact with a zeolite catalyst, wherein the method for treating the zeolite catalyst according to any one of claims 1 to 6 is carried out. A method for producing a lower olefin, including.