JP2012241173A - Method for producing monocyclic aromatic hydrocarbon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing monocyclic aromatic hydrocarbons capable of producing 6-8C monocyclic aromatic hydrocarbons in high yield from oil feedstock containing polycyclic aromatic hydrocarbons.SOLUTION: The method for producing 6-8C monocyclic aromatic hydrocarbons includes: a decomposition reforming reaction step of bringing oil feedstock into contact with a catalyst for producing monocyclic aromatic hydrocarbons to react them with each other for obtaining a product containing 6-8C monocyclic aromatic hydrocarbons and a ≥9C heavy distillate; a catalyst separation step of separating and removing the catalyst for producing monocyclic aromatic hydrocarbons and tricyclic aromatic hydrocarbons contained in the product from a mixture comprising the product, which is derived from the decomposition reforming reaction step, and the catalyst for producing monocyclic aromatic hydrocarbons, which slightly accompanies the product; and a purification and recovery step of purifying and recovering the 6-8C monocyclic aromatic hydrocarbons separated from the product generated in the decomposition reforming reaction step.

Description

 The present invention relates to a method for producing a monocyclic aromatic hydrocarbon by a catalytic aromatic production reaction.

 Light cycle oil (hereinafter referred to as “LCO”), which is a cracked light oil produced by a fluid catalytic cracker, contains a large amount of polycyclic aromatic hydrocarbons and has been utilized as a light oil or heavy oil. However, in recent years, it has been proposed to obtain monocyclic aromatic hydrocarbons (for example, benzene, toluene, xylene, ethylbenzene, etc.) that can be used as a high octane gasoline base material or petrochemical raw material and have high added value from LCO. (For example, see Patent Documents 1 to 4).

JP-A-3-2128 Japanese Patent Laid-Open No. 3-52993 JP-A-3-26791 International Publication No. 2010/109899 Pamphlet

 However, in the methods described in Patent Documents 1 to 4, it cannot be said that the yield of monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms is necessarily high enough. That is, in the method, many by-products having relatively low added value other than the intended monocyclic aromatic hydrocarbon having 6 to 8 carbon atoms were produced.

 The present invention has been made to solve the above-described problems, and can produce monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms in high yield from a raw material oil containing polycyclic aromatic hydrocarbons. It aims at providing the manufacturing method of hydrocarbon.

[1] A monocyclic aromatic hydrocarbon for producing a monocyclic aromatic hydrocarbon having 6 to 8 carbon atoms from a feedstock having a 10 vol% distillation temperature of 140 ° C or higher and a 90 vol% distillation temperature of 380 ° C or lower A manufacturing method of
The raw material oil is contacted with a catalyst for producing monocyclic aromatic hydrocarbons containing crystalline aluminosilicate and reacted to produce a monocyclic aromatic hydrocarbon having 6 to 8 carbon atoms and a heavy hydrocarbon having 9 or more carbon atoms. A cracking and reforming reaction step to obtain a product containing a fraction;
The monocyclic aromatic hydrocarbon production catalyst derived from the cracking and reforming reaction step, from a mixture of the product and the monocyclic aromatic hydrocarbon production catalyst slightly entrained by the product Catalyst separation step of separating and removing together with the tricyclic aromatic hydrocarbon contained in the product,
And a purification / recovery step for purifying and recovering the monocyclic aromatic hydrocarbon having 6 to 8 carbon atoms separated from the product produced in the cracking / reforming reaction step.
[2] In the catalyst removal step, the heavy fraction separated in the separation step for separating the product generated in the cracking reforming reaction step into a plurality of fractions is derived from the cracking reforming reaction step. The monocyclic aromatic hydrocarbon production catalyst is removed from the mixture by contacting with the mixture of the product and the monocyclic aromatic hydrocarbon production catalyst entrained by the product. The method for producing a monocyclic aromatic hydrocarbon according to [1], wherein:
[3] The heavy fraction separated in the separation step contains a tricyclic aromatic hydrocarbon as a main component, and the monocyclic aromatic hydrocarbon according to [1] or [2] Production method.

According to the method for producing a monocyclic aromatic hydrocarbon of the present invention, it is possible to produce a monocyclic aromatic hydrocarbon having 6 to 8 carbon atoms in a high yield from a raw material oil containing a polycyclic aromatic hydrocarbon.
In particular, in the catalyst separation step, the product derived from the cracking and reforming reaction step and the small amount of monocyclic aromatic hydrocarbon production catalyst accompanying the product are separated and removed, so that the subsequent processing is blocked. It is possible to carry out smoothly without disturbing the problems and equipment.

It is a figure for demonstrating embodiment of the manufacturing method of the monocyclic aromatic hydrocarbon of this invention.

Hereinafter, embodiments of the method for producing monocyclic aromatic hydrocarbons of the present invention will be described.
The manufacturing method of the monocyclic aromatic hydrocarbon of this embodiment is a method of manufacturing a C6-C8 monocyclic aromatic hydrocarbon from raw material oil, Comprising: The process of the following (a)-(f) is carried out. It is a method to have. FIG. 1 is a schematic configuration diagram of a manufacturing plant for explaining the present embodiment.

(A) The feedstock oil is brought into contact with the catalyst for monocyclic aromatic hydrocarbon production by the cracking reforming reactor 10 and reacted to produce a monocyclic aromatic hydrocarbon having 6 to 8 carbon atoms and 9 or more carbon atoms. A cracking and reforming reaction step for obtaining a product containing a heavy fraction (b) consisting of a product derived from the cracking and reforming reaction step and a catalyst for producing monocyclic aromatic hydrocarbons accompanying the product. The catalyst separation step (c) is derived from the catalyst separation step in which the catalyst for monocyclic aromatic hydrocarbons is separated and removed from the mixture by the washing tower 12 and the catalyst separation device 14 together with the tricyclic aromatic hydrocarbons contained in the product. From the derived product, at least a monocyclic aromatic hydrocarbon having 6 to 8 carbon atoms (benzene / toluene / xylene) and a heavy fraction having 9 carbon atoms are separated by the first separator 16 and the second separator 18. Separated in the separation step (d) separation step In the purification and recovery step (e) separation step in which the monocyclic aromatic hydrocarbon having 6 to 8 primes is purified and recovered by the purification and recovery device 20, in the separation step, the tricyclic aromatic hydrocarbons separated from the derivation derived from the catalyst separation step The hydrogen recovery device 30 converts hydrogen produced as a by-product in the cracking and reforming reaction step from the gas component separated in the tricyclic aromatic hydrocarbon supply step (f) separation step supplied to the catalyst separation step by the return lines 24 and 26. Recovery process to recover by

Of the steps (a) to (f), the steps (a), (b), and (d) are essential steps in the invention according to claim 1, and (c), (e), ( Step f) is an optional step.
Hereinafter, each step will be specifically described.

Hereinafter, each step will be specifically described.
<Decomposition and reforming reaction process>
In the cracking and reforming reaction step, the raw material oil is introduced into the cracking and reforming reactor 10 filled with the catalyst for producing monocyclic aromatic hydrocarbons, and brought into contact with the catalyst for producing monocyclic aromatic hydrocarbons to be reacted. . As a result, the saturated hydrocarbon contained in the feedstock is used as the hydrogen donor source, and the polycyclic aromatic hydrocarbon is partially hydrogenated by the hydrogen transfer reaction from the saturated hydrocarbon, and the ring is opened to form the monocyclic aromatic hydrocarbon. Convert. It can also be converted to monocyclic aromatic hydrocarbons by cyclization and dehydrogenation of saturated hydrocarbons obtained in the feedstock or in the cracking process. Furthermore, a C6-C8 monocyclic aromatic hydrocarbon can also be obtained by decomposing | disassembling a C9 or more monocyclic aromatic.

However, tricyclic aromatic hydrocarbons are not converted to monocyclic aromatic hydrocarbons because they have low reactivity in the cracking and reforming reaction step even if they are hydrogenated reactants. Derived with the object. In addition to monocyclic aromatic hydrocarbons, the product includes hydrogen, methane, ethane, LPG, heavy fractions having 9 or more carbon atoms, and the like.
In this cracking and reforming reaction step, when the product is derived, the catalyst for producing the monocyclic aromatic hydrocarbon is also slightly derived by being accompanied by the product. Therefore, in this cracking and reforming reaction step, a mixture of the product and the catalyst for producing monocyclic aromatic hydrocarbons is derived from the cracking and reforming reactor 10.

(Raw oil)
The feedstock oil used in the present invention is an oil having a 10 vol% distillation temperature of 140 ° C or higher and a 90 vol% distillation temperature of 380 ° C or lower. In the case of an oil having a 10% by volume distillation temperature of less than 140 ° C., a monocyclic aromatic hydrocarbon is produced from a light oil, and a monocyclic aromatic carbonization is produced from a feed oil containing the polycyclic aromatic hydrocarbon of the present invention. It becomes unsuitable for the purpose of producing hydrogen. In addition, when oil having a 90% by volume distillation temperature exceeding 380 ° C. is used, the yield of monocyclic aromatic hydrocarbons is lowered and coke deposition on the catalyst for producing monocyclic aromatic hydrocarbons The amount tends to increase and cause a sharp decrease in catalyst activity.
The 10 vol% distillation temperature of the feedstock oil is preferably 150 ° C or higher, and the 90 vol% distillation temperature of the feedstock oil is preferably 360 ° C or lower.

In addition, 10 volume% distillation temperature and 90 volume% distillation temperature here mean the value measured based on JISK2254 "petroleum product-distillation test method".
Examples of the feed oil having a 10% by volume distillation temperature of 140 ° C. or higher and a 90% by volume distillation temperature of 380 ° C. or lower include cracked light oil (LCO) produced by a fluid catalytic cracker, LCO hydrorefined oil, Examples include coal liquefied oil, heavy oil hydrocracked refined oil, straight-run kerosene, straight-run light oil, coker kerosene, coker light oil, and oil sand hydrocracked refined oil.
Polycyclic aromatic hydrocarbons have low reactivity and are difficult to convert to monocyclic aromatic hydrocarbons in the cracking and reforming reaction step of the present invention. However, on the other hand, when polycyclic aromatic hydrocarbons are hydrogenated in the hydrogenation reaction step, they are converted into naphthenobenzenes and recycled to the cracking and reforming reaction step, thereby becoming monocyclic aromatic hydrocarbons. Convertible. Therefore, it does not specifically limit regarding containing many polycyclic aromatic hydrocarbons in raw material oil. However, among polycyclic aromatic hydrocarbons, aromatic hydrocarbons having 3 or more rings consume a large amount of hydrogen in the hydrogenation reaction step, and even in the hydrogenation reaction product, the reactivity in the cracking and reforming reaction step is low. Since it is low, it is not preferable to include a large amount. Therefore, the aromatic hydrocarbon of 3 or more rings in the feed oil is preferably 25% by volume or less, and more preferably 15% by volume or less.
In addition, as raw material oil containing the bicyclic aromatic hydrocarbon converted into naphthenobenzene by a hydrogenation reaction process, and reducing the aromatic hydrocarbon of 3 or more rings, 90 volume of raw material oil is mentioned, for example It is more preferable that the% distillation temperature is 330 ° C. or lower.

 The polycyclic aromatic hydrocarbon referred to here is measured according to JPI-5S-49 “Petroleum products—Hydrocarbon type test method—High-performance liquid chromatograph method”, FID gas chromatograph method or two-dimensional gas chromatograph. It means the total value of the bicyclic aromatic hydrocarbon content (bicyclic aromatic content) and the tricyclic or higher aromatic hydrocarbon content (tricyclic or higher aromatic content) analyzed by the tograph method. Thereafter, when the content of polycyclic aromatic hydrocarbon, bicyclic aromatic hydrocarbon, tricyclic or higher aromatic hydrocarbon is indicated by volume%, it was measured according to JPI-5S-49. When it is shown by mass%, it is measured based on the FID gas chromatographic method or the two-dimensional gas chromatographic method.

(Reaction format)
Examples of the reaction mode when the raw material oil is brought into contact with and reacted with the catalyst for monocyclic aromatic hydrocarbon production, that is, the reaction system of the cracking reforming reactor 10 include a fixed bed, a moving bed, a fluidized bed and the like. In the present invention, since the heavy component is used as a raw material, a fluidized bed capable of continuously removing the coke adhering to the catalyst and capable of performing the reaction stably is preferable. A continuous regenerative fluidized bed is particularly preferred in which the catalyst circulates between them and the reaction-regeneration can be repeated continuously. The feedstock oil in contact with the catalyst for producing monocyclic aromatic hydrocarbons is preferably in a gas phase. Moreover, you may dilute a raw material with gas as needed.

(Catalyst for monocyclic aromatic hydrocarbon production)
The catalyst for monocyclic aromatic hydrocarbon production contains crystalline aluminosilicate.

[Crystalline aluminosilicate]
The crystalline aluminosilicate is preferably a medium pore zeolite and / or a large pore zeolite because the yield of monocyclic aromatic hydrocarbons can be further increased.
The medium pore zeolite is a zeolite having a 10-membered ring skeleton structure. Examples of the medium pore zeolite include AEL type, EUO type, FER type, HEU type, MEL type, MFI type, NES type, and TON type. And zeolite having a WEI type crystal structure. Among these, the MFI type is preferable because the yield of monocyclic aromatic hydrocarbons can be further increased.
The large pore zeolite is a zeolite having a 12-membered ring skeleton structure. Examples of the large pore zeolite include AFI type, ATO type, BEA type, CON type, FAU type, GME type, LTL type, and MOR type. , Zeolites of MTW type and OFF type crystal structures. Among these, the BEA type, FAU type, and MOR type are preferable in terms of industrial use, and the BEA type is preferable because the yield of monocyclic aromatic hydrocarbons can be further increased.

The crystalline aluminosilicate may contain, in addition to the medium pore zeolite and the large pore zeolite, a small pore zeolite having a skeleton structure having a 10-membered ring or less, and a very large pore zeolite having a skeleton structure having a 14-membered ring or more. Good.
Here, examples of the small pore zeolite include zeolites having crystal structures of ANA type, CHA type, ERI type, GIS type, KFI type, LTA type, NAT type, PAU type, and YUG type.
Examples of the ultra-large pore zeolite include zeolites having CLO type and VPI type crystal structures.

When the cracking and reforming reaction step is a fixed bed reaction, the content of the crystalline aluminosilicate in the monocyclic aromatic hydrocarbon production catalyst is 100% by mass based on the entire monocyclic aromatic hydrocarbon production catalyst. 60-100 mass% is preferable, 70-100 mass% is more preferable, 90-100 mass% is especially preferable. If the content of the crystalline aluminosilicate is 60% by mass or more, the yield of monocyclic aromatic hydrocarbons can be sufficiently increased.
When the cracking and reforming reaction step is a fluidized bed reaction, the content of crystalline aluminosilicate in the monocyclic aromatic hydrocarbon production catalyst is 100% by mass of the total monocyclic aromatic hydrocarbon production catalyst. 20-60 mass% is preferable, 30-60 mass% is more preferable, and 35-60 mass% is especially preferable. If the content of the crystalline aluminosilicate is 20% by mass or more, the yield of monocyclic aromatic hydrocarbons can be sufficiently increased. When the content of the crystalline aluminosilicate exceeds 60% by mass, the content of the binder that can be blended with the catalyst is reduced, which may be unsuitable for fluidized beds.

[Phosphorus, Boron]
The catalyst for producing monocyclic aromatic hydrocarbons preferably contains phosphorus and / or boron. If the catalyst for producing monocyclic aromatic hydrocarbons contains phosphorus and / or boron, it is possible to prevent the yield of monocyclic aromatic hydrocarbons from decreasing with time, and to suppress the formation of coke on the catalyst surface.

As a method for incorporating phosphorus into the monocyclic aromatic hydrocarbon production catalyst, for example, phosphorus is supported on crystalline aluminosilicate, crystalline aluminogallosilicate, or crystalline aluminodine silicate by an ion exchange method, an impregnation method, or the like. Examples thereof include a method, a method in which a phosphorus compound is contained during zeolite synthesis and a part of the skeleton of the crystalline aluminosilicate is replaced with phosphorus, and a method in which a crystal accelerator containing phosphorus is used during zeolite synthesis. The phosphate ion-containing aqueous solution used at that time is not particularly limited, but was prepared by dissolving phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, and other water-soluble phosphates in water at an arbitrary concentration. Can be preferably used.
As a method for incorporating boron into the catalyst for monocyclic aromatic hydrocarbon production, for example, boron is supported on crystalline aluminosilicate, crystalline aluminogallosilicate, or crystalline aluminodine silicate by an ion exchange method, an impregnation method, or the like. Examples thereof include a method, a method in which a boron compound is contained at the time of zeolite synthesis and a part of the skeleton of the crystalline aluminosilicate is replaced with boron, a method in which a crystal accelerator containing boron is used at the time of zeolite synthesis, and the like.

 The phosphorus and / or boron content in the monocyclic aromatic hydrocarbon production catalyst is preferably 0.1 to 10% by mass, based on 100% by mass of the entire catalyst, and 0.5 to 9% by mass. More preferably, it is 0.5-8 mass%. If the content of phosphorus and / or boron with respect to the total mass of the catalyst is 0.1% by mass or more, a decrease in the yield of monocyclic aromatic hydrocarbons over time can be prevented, and by being 10% by mass or less, The yield of cyclic aromatic hydrocarbons can be increased.

[Gallium, zinc]
The catalyst for producing monocyclic aromatic hydrocarbons can contain gallium and / or zinc, if necessary. If gallium and / or zinc is contained, the production rate of monocyclic aromatic hydrocarbons can be increased.

The gallium-containing form in the monocyclic aromatic hydrocarbon production catalyst is one in which gallium is incorporated into the lattice skeleton of crystalline aluminosilicate (crystalline aluminogallosilicate), and gallium is supported on the crystalline aluminosilicate. And those containing both (gallium-supporting crystalline aluminosilicate).
In the catalyst for producing monocyclic aromatic hydrocarbons, the zinc-containing form is one in which zinc is incorporated in the lattice skeleton of crystalline aluminosilicate (crystalline aluminodine silicate), or zinc is supported on crystalline aluminosilicate. One (zinc-supporting crystalline aluminosilicate) and one containing both.

Crystalline aluminogallosilicate and crystalline aluminodine silicate have a structure in which SiO ₄ , AlO ₄ and GaO ₄ / ZnO ₄ structures are present in the skeleton. In addition, crystalline aluminogallosilicate and crystalline aluminodine silicate are, for example, gel crystallization by hydrothermal synthesis, a method of inserting gallium or zinc into the lattice skeleton of crystalline aluminosilicate, or crystalline gallosilicate or crystalline It is obtained by inserting aluminum into the lattice skeleton of zincosilicate.

The gallium-supporting crystalline aluminosilicate is obtained by supporting gallium on a crystalline aluminosilicate by a known method such as an ion exchange method or an impregnation method. The gallium source used in this case is not particularly limited, and examples thereof include gallium salts such as gallium nitrate and gallium chloride, and gallium oxide.
The zinc-supporting crystalline aluminosilicate is obtained by supporting zinc on a crystalline aluminosilicate by a known method such as an ion exchange method or an impregnation method. Although it does not specifically limit as a zinc source used in that case, Zinc salts, such as zinc nitrate and zinc chloride, zinc oxide, etc. are mentioned.

 When the catalyst for monocyclic aromatic hydrocarbon production contains gallium and / or zinc, the content of gallium and / or zinc in the catalyst for monocyclic aromatic hydrocarbon production is based on 100% by mass of the entire catalyst. It is preferable that it is 0.01-5.0 mass%, and it is more preferable that it is 0.05-2.0 mass%. If the content of gallium and / or zinc is 0.01% by mass or more, the production rate of monocyclic aromatic hydrocarbons can be increased, and if it is 5.0% by mass or less, the monocyclic aromatic hydrocarbons The yield can be higher.

[shape]
The catalyst for monocyclic aromatic hydrocarbon production is, for example, in the form of powder, granules, pellets, etc., depending on the reaction mode. For example, in the case of a fluidized bed as in this embodiment, it is in the form of powder, and in the case of a fixed bed as in another embodiment, it is in the form of particles or pellets. The average particle size of the catalyst used in the fluidized bed is preferably 30 to 180 μm, more preferably 50 to 100 μm. The bulk density of the catalyst used in the fluidized bed is preferably 0.4 to 1.8 g / cc, more preferably 0.5 to 1.0 g / cc.
In addition, an average particle diameter represents the particle size used as 50 mass% in the particle size distribution obtained by the classification by a sieve, and a bulk density is the value measured by the method of JIS specification R9301-2-3.
When obtaining a granular or pellet-shaped catalyst, if necessary, an inert oxide may be blended into the catalyst as a binder and then molded using various molding machines.

 When the catalyst for monocyclic aromatic hydrocarbon production contains an inorganic oxide such as a binder, one containing phosphorus as the binder may be used.

(Reaction temperature)
The reaction temperature when the raw material oil is brought into contact with and reacted with the catalyst for producing a monocyclic aromatic hydrocarbon is not particularly limited, but is preferably 400 to 650 ° C. If the minimum of reaction temperature is 400 degreeC or more, raw material oil can be made to react easily, More preferably, it is 450 degreeC or more. Moreover, if the upper limit of reaction temperature is 650 degrees C or less, the yield of monocyclic aromatic hydrocarbon can be made high enough, More preferably, it is 600 degrees C or less.

(Reaction pressure)
The reaction pressure when the raw material oil is brought into contact with and reacted with the catalyst for producing a monocyclic aromatic hydrocarbon is preferably 1.5 MPaG or less, and more preferably 1.0 MPaG or less. If the reaction pressure is 1.5 MPaG or less, the by-product of light gas can be suppressed and the pressure resistance of the reactor can be lowered.

(Contact time)
The contact time between the feedstock and the catalyst for producing monocyclic aromatic hydrocarbons is not particularly limited as long as the desired reaction proceeds substantially. For example, the gas passage time on the catalyst for producing monocyclic aromatic hydrocarbons 1 to 300 seconds are preferable, and the lower limit is more preferably 5 seconds and the upper limit is more preferably 150 seconds. If the contact time is 1 second or longer, the reaction can be performed reliably. If the contact time is 300 seconds or shorter, accumulation of carbonaceous matter in the catalyst due to coking or the like can be suppressed. Or the generation amount of the light gas by decomposition | disassembly can be suppressed.

<Catalyst separation step>
In the catalyst separation step, the product derived from the cracking and reforming reaction step (cracking reforming reactor 10) and the catalyst for the production of monocyclic aromatic hydrocarbons accompanying the product (hereinafter simply referred to as catalyst) The catalyst is removed from the mixture consisting of: In addition, tricyclic aromatic hydrocarbons contained in the product are also separated and removed.

That is, the catalyst separation step includes a washing tower 12 to which the mixture is supplied, and a catalyst separator 14 that separates and removes the catalyst by solid-liquid separation of a heavy fraction derived from the washing tower 12. It is configured.
The operation in the cleaning tower 12 will be described.
The product vapor from the partial reforming reactor 10 is supplied to the lower part of the washing tower 12. In the washing tower 12, the bottom liquid of the washing tower 12 is extracted, pressurized by a pump, cooled by a heat exchanger, and then circulated to the middle stage of the washing tower 12. In the washing tower 12, the vapor reaction product and the circulating liquid come into countercurrent contact with each other, whereby the entrained catalyst particles slightly contained in the reaction product from the cracking reforming reactor 10 are trapped in the circulating liquid. Thus, the catalyst particles from the reaction product can be removed. However, since the circulating liquid itself is also circulated, a trace amount of catalyst is also present in the circulating liquid in the middle stage of the washing tower 12. When the gas-liquid countercurrent contact is made, it is inevitable that the droplets are accompanied, and the catalyst is also contained in the droplets. As a result, a very small amount of catalyst remains in the vapor of the reaction product. In order to capture and separate the droplets containing the entrained catalyst particles, the heavy fraction separated in the first separation device 16 containing no catalyst at the top of the washing tower 12 and / or the heavy fraction separated in the purification and recovery step is used. A mass fraction (containing a large amount of tricyclic aromatic hydrocarbons) is supplied. In this way, most of the catalyst is removed at the bottom of the washing tower 12 by the circulating liquid at the bottom of the column, and the reaction product of the vapor containing a very small amount of catalyst and the heavy fraction from the first separator 16 containing no catalyst at all. The catalyst particles are removed by a two-step process in which the minute portion is brought into countercurrent contact with the upper portion to capture droplets containing the catalyst.
For example, the washing tower 12 is provided with a buckle tray inside and has a theoretical plate set to about three, and the mixture supplied at a high temperature (for example, 550 ° C.) is supplied to an external cooler (not shown). The catalyst is separated from the product which has been cooled and partially liquefied while being circulated and cooled. The washing tower 12 is supplied with tricyclic aromatic hydrocarbons as a washing liquid from a separation step described later. This washing liquid wash | cleans the said product in the gas-liquid mixed state in the washing tower 12, and transfers a catalyst contained in this product in a washing | cleaning liquid, thereby efficiently separating the catalyst from the product. Remove.

 The washing tower 12 is composed of gas components such as hydrogen, methane and ethane, light components such as LPG, monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms, monocyclic aromatic hydrocarbons having 9 or more carbon atoms, carbon Some heavy fractions of several tens or more are derived from the top of the column, while heavy fractions such as polycyclic aromatic hydrocarbons mainly composed of tricyclic aromatic hydrocarbons and the catalyst are derived from the bottom of the column. To do. However, since the tricyclic aromatic hydrocarbons are supplied to the washing tower 12 as a washing liquid from the separation step described later, the heavy fraction derived from the bottom of the washing tower 12 contains the inside of the washing tower 12. All the tricyclic aromatic hydrocarbons in the mixture are not included, but only a part thereof is included. That is, only a part of the tricyclic aromatic hydrocarbons in the mixture in the cleaning tower 12 is derived without being derived from the bottom of the tower. It should be noted that the heavy fraction derived from the tower bottom includes a heavy fraction such as a bicyclic aromatic hydrocarbon in addition to the tricyclic aromatic hydrocarbon.

 The catalyst separator 14 is configured to have, for example, a filter, and separates and removes the heavy fraction containing the catalyst derived from the washing tower 12 by solid-liquid separation and separates and removes the catalyst from the heavy fraction. It is. For the separated catalyst, for example, it may be sent to a catalyst regeneration tower (not shown), regenerated here, and then recycled to the cracking and reforming reaction step. May be. For heavy fractions after removal of the catalyst, that is, polycyclic aromatic hydrocarbons mainly composed of tricyclic aromatic hydrocarbons, for example, use them as fuel (torch oil) for heating the catalyst regeneration tower. Can do.

<Separation process>
In the separation step, a monocyclic aromatic hydrocarbon having at least 6 to 8 carbon atoms and a heavy fraction having 9 or more carbon atoms are obtained from a derived product derived from the top of the washing tower 12 (catalyst separation step) by a plurality of separation devices. Separate the minutes.
That is, this separation step is configured to include the first separation device 16 and the debutizer (second separation device) 18 in the present embodiment. However, the separation step of the present invention does not necessarily require these two separation devices, and can be constituted by, for example, a single or a plurality of distillation devices. Therefore, the debutizer (second separator) 18 can be omitted. Moreover, you may comprise a separation process including the 3rd separation apparatus 22 mentioned later as needed.

The first separation device 16 separates a gas component such as hydrogen, methane, ethane and the liquid fraction from the derived product. A known gas-liquid separator is used as the first separator 16. As an example of the gas-liquid separation device, a gas-liquid separation tank, a product introduction pipe for introducing a product into the gas-liquid separation tank, a gas component outflow pipe provided at an upper part of the gas-liquid separation tank, What comprises the liquid component outflow pipe | tube provided in the lower part of the gas-liquid separation tank is mentioned.
In the present embodiment, gas-liquid separation devices are arranged in two stages, cooled in the front stage 16a, and a heavy fraction mainly composed of tricyclic aromatic hydrocarbons in the liquid fraction (hereinafter referred to as tricyclic aromatic hydrocarbons). And the pressure is increased in the subsequent stage 16b to separate the gas component and the liquid fraction after separation of the tricyclic aromatic hydrocarbon.
The debutizer 18 (second separator) includes an LPG fraction containing butane and the like from the liquid fraction separated by the first separator 16 and a crude aromatic fraction containing a large amount of monocyclic aromatic hydrocarbons having 6 or more carbon atoms. And to separate.

<Tricyclic aromatic hydrocarbon supply process>
The tricyclic aromatic hydrocarbons separated in the first stage 16a (first separation device 16) in the first separation device 16 are returned to the washing tower 12 (catalyst separation step) as a washing liquid by the first return line 24. That is, the first return line 24 constitutes a tricyclic aromatic hydrocarbon supply process for supplying the tricyclic aromatic hydrocarbon as a cleaning liquid to the catalyst separation process.
Note that the tricyclic aromatic hydrocarbon supply step of the present invention is not limited to the first return line 24 but may be configured by, for example, a second return line 26 described later. 24 and the second return line 26 may be used. Further, the tricyclic aromatic hydrocarbon may be separated in another process after the first separator 16 and supplied to the catalyst separation step as a cleaning liquid. In this case, the tricyclic aromatic carbonization may be performed. The hydrogen supply process is also a tricyclic aromatic hydrocarbon supply process.
By supplying the tricyclic aromatic hydrocarbon as a cleaning liquid to the cleaning tower 12, the product in a gas-liquid mixed state is cleaned in the cleaning tower 12, and the catalyst contained in the product is placed in the cleaning liquid. The catalyst can be efficiently separated and removed from the product. A part of the tricyclic aromatic hydrocarbons supplied to the washing tower 12 is led to the catalyst separator 14 together with the catalyst. Further, the remaining portion stays in the washing tower 12 or is sent to the first separation device 16.

<Purification and recovery process>
In the purification and recovery step, the monocyclic aromatic hydrocarbon having 6 to 8 carbon atoms separated in the separation step is purified and recovered by the purification and recovery device 20.
The purification and recovery device 20 is composed of a monocyclic aromatic hydrocarbon (benzene / toluene / xylene) having 6 to 8 carbon atoms and a heavy fraction, that is, mainly having 9 or more carbon atoms, from the crude aromatic fraction obtained by the debutizer 18. Into heavy fractions. The separated monocyclic aromatic hydrocarbon having 6 to 8 carbon atoms is further purified to recover benzene, toluene and xylene, respectively. As such a purification and recovery apparatus 20, a known distillation apparatus, for example, a multistage distillation apparatus such as a stripper is used.

 The third separation device 22 separates the heavy fraction separated from the purification and recovery device 20 into a heavy fraction having 9 carbon atoms and a heavy fraction having 10 or more carbon atoms. And about the heavy fraction of carbon number 9, this is collect | recovered and used as a base material etc. of various products. On the other hand, the heavy fraction having 10 or more carbon atoms is sent back to the recycle process to be returned to the cracking and reforming reaction process and used for the cracking and reforming reaction in the cracking and reforming reactor 10 together with the raw material oil. However, the third separation device 22 is not essential in the present invention, and may be omitted, and the heavy fraction having 9 or more carbon atoms separated from the purification and recovery device 20 may be directly sent to the recycling process. Good.

 Here, the heavy fraction separated from the monocyclic aromatic hydrocarbon having 6 to 8 carbon atoms by the purification and recovery apparatus 20 is a heavy fraction having 9 or more carbon atoms, and is a polycyclic aromatic hydrocarbon. As a main component, it contains a large amount of naphthalene and alkylnaphthalenes. It also contains a small amount of tricyclic aromatic hydrocarbons. That is, tricyclic aromatic hydrocarbons that could not be separated by the washing tower 12 or the first separation device 16 are contained in the heavy fraction. Therefore, the tricyclic aromatic hydrocarbons are separated by the third separator 22 as a heavy fraction having 10 or more carbon atoms.

As described above, tricyclic aromatic hydrocarbons, for example, are low in reactivity in the cracking and reforming reaction process even if they are hydrogenated reactants, and are hardly converted to monocyclic aromatic hydrocarbons. Recycling to the reforming reaction process does not contribute to improving reaction efficiency.
Therefore, the third separation device 22 not only separates the heavy fraction separated from the monocyclic aromatic recovery device 20 into a heavy fraction having 9 carbon atoms and a heavy fraction having 10 or more carbon atoms. The tricyclic aromatic hydrocarbon may be separated from the heavy fraction having 9 or more carbon atoms. The separated tricyclic aromatic hydrocarbons are returned to the cleaning tower 12 (catalyst separation step) as a cleaning liquid by the second return line 26. In this case, the second return line 26, together with the first return line 24, constitutes a 3-ring aromatic hydrocarbon supply step for supplying the 3-ring aromatic hydrocarbon as a cleaning liquid to the catalyst separation step as described above. Will be.

 However, the amount of tricyclic aromatic hydrocarbons separated by the third separation device 22 is not so large. Therefore, considering the increase in equipment cost and operating cost due to separation of tricyclic aromatic hydrocarbons, the third separation is performed when there is little economic effect by separating and returning the tricyclic aromatic hydrocarbons. Separation of tricyclic aromatic hydrocarbons in the apparatus 22 may be omitted.

<Hydrogen recovery process>
In the hydrogen recovery step, hydrogen produced as a by-product in the cracking and reforming reaction step (cracking reforming reactor 10) from the gas component obtained in the separating step (the rear stage 16b of the first separator 16) is converted into a hydrogen recovery device 30. Collect by.
The method for recovering hydrogen is not particularly limited as long as hydrogen contained in the gas component obtained in the separation step and other gas can be separated. For example, the pressure fluctuation adsorption method (PSA method), the cryogenic separation method, Examples thereof include a membrane separation method. Therefore, as the hydrogen recovery apparatus 30, an apparatus (for example, a PSA apparatus) that recovers hydrogen based on these methods is used.
Usually, the amount of hydrogen recovered in the hydrogen recovery step is larger than the amount necessary for hydrogenating a heavy fraction having 10 or more carbon atoms.

"Other embodiments"
The present invention is not limited to the same as the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. Tricyclic aromatic hydrocarbons are separated and removed from the mixture derived from the cracking and reforming reaction step in the catalyst separation step, and then the resulting heavy fraction having 10 or more carbon atoms is returned to the cracking and reforming reaction step. Therefore, the heavy fraction returned to the cracking and reforming reaction step hardly contains tricyclic aromatic hydrocarbons that are difficult to be converted into monocyclic aromatic hydrocarbons in the cracking and reforming reaction step. The conversion efficiency of the recycled heavy fraction (or its hydrogenation reaction product) into monocyclic aromatic hydrocarbons is improved. Therefore, the yield of the general monocyclic aromatic hydrocarbon with respect to the supply amount of raw material oil can be improved, and the yield of monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms can be increased.

In addition, since the tricyclic aromatic hydrocarbons are separated in the separation step, the tricyclic aromatic hydrocarbon content of the heavy fraction to be recycled (or the hydrogenation reaction product thereof) can be reduced, Thereby, the conversion efficiency of the heavy fraction into monocyclic aromatic hydrocarbons can be improved.
Further, since the tricyclic aromatic hydrocarbons separated in the separation step are supplied to the catalyst separation step as a cleaning liquid by the tricyclic aromatic hydrocarbon supply step by the first return line 24 and the second return line 26, in the catalyst separation step The catalyst can be separated and removed more efficiently.

 INDUSTRIAL APPLICABILITY The present invention is useful for the production of monocyclic aromatic hydrocarbons using, as raw materials, LCO obtained from an FCC device and kerosene, light oil obtained from a crude oil distillation device.

DESCRIPTION OF SYMBOLS 10 ... Decomposition | reformation reforming reactor, 12 ... Washing tower, 14 ... Catalyst separation apparatus, 16 ... 1st separation apparatus, 18 ... Debutizer (2nd separation apparatus), 20 ... Purification and recovery apparatus, 22 ... 3rd separation apparatus, 24 ... 1st return line, 26 ... 2nd return line, 30 ... Hydrogen recovery apparatus.

Claims (3)

Monocyclic aromatic hydrocarbon production method for producing monocyclic aromatic hydrocarbons having 6 to 8 carbon atoms from a raw material oil having a 10 vol% distillation temperature of 140 ° C or higher and a 90 vol% distillation temperature of 380 ° C or lower Because
The raw material oil is contacted with a catalyst for producing monocyclic aromatic hydrocarbons containing crystalline aluminosilicate and reacted to produce a monocyclic aromatic hydrocarbon having 6 to 8 carbon atoms and a heavy hydrocarbon having 9 or more carbon atoms. A cracking and reforming reaction step to obtain a product containing a fraction;
The monocyclic aromatic hydrocarbon production catalyst derived from the cracking and reforming reaction step, from a mixture of the product and the monocyclic aromatic hydrocarbon production catalyst slightly entrained by the product Catalyst separation step of separating and removing together with the tricyclic aromatic hydrocarbon contained in the product,
And a purification and recovery step for purifying and recovering the monocyclic aromatic hydrocarbon having 6 to 8 carbon atoms separated from the product produced in the cracking and reforming reaction step. A method for producing hydrocarbons.  In the catalyst removal step, the heavy fraction separated in the separation step of separating the product produced in the cracking reforming reaction step into a plurality of fractions is derived from the cracking reforming reaction step. The catalyst for producing monocyclic aromatic hydrocarbons is removed from the mixture by contacting with the mixture comprising the product and the catalyst for producing monocyclic aromatic hydrocarbons accompanying the product. The method for producing a monocyclic aromatic hydrocarbon according to claim 1. The method for producing monocyclic aromatic hydrocarbons according to claim 1 or 2, wherein the heavy fraction separated in the separation step contains a tricyclic aromatic hydrocarbon as a main component.

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