JP2016188192A - Method for producing butadiene-containing product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a butadiene-containing product, in which the butadiene-containing product is produced industrially advantageously from a n-butane-containing raw material by a one-step dehydration reaction.SOLUTION: The method for producing the butadiene-containing product comprises a step of bringing the n-butane-containing raw material into contact with a dehydration catalyst, which is packed in one adiabatic reactor or multiple adiabatic reactors, to perform the dehydration reaction. The outlet pressure of the reactor on the most downstream side is made equal to or higher than 0.01 MPa and lower than 0.1 MPa. A molar ratio (steam/4C hydrocarbons) of the steam in reactor feed components to the 4C hydrocarbons therein at an inlet of the reactor on the most upstream side is made within 1-16. When the partial pressure of a reaction component in the presence of the steam is lowered and the total amount of the 4C hydrocarbons in the reactor feed components at the inlet of the reactor on the most upstream side is 100 mol%, the total amount of n-butane and n-butene is made equal to or higher than 40 mol%.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a product containing butadiene by dehydrogenation of butane.

  Butadiene is an important chemical, and is used as a raw material for synthetic rubber such as SBR (styrene butadiene rubber) or NBR (acrylonitrile butadiene rubber), as a raw material for ABS (acrylonitrile butadiene styrene) resin and nylon 66. Currently, most of butadiene is produced by extraction from a C4 fraction made of isobutene, n-butene, butadiene and the like obtained by pyrolyzing a naphtha fraction of petroleum. In addition, there is a production method in which butadiene is produced by oxidative dehydrogenation of n-butene of the same C4 fraction, but in order to produce butadiene economically, a certain amount of n or more is contained in the C4 fraction. -Butene needs to be included. However, the demand for butadiene greatly exceeds the production of the C4 fraction, and a new butadiene production method is eagerly desired.

  In addition, a method for producing a large amount of ethylene from inexpensive ethane gas is increasingly used year by year. However, unlike naphtha decomposition, this production method does not provide components such as butadiene, so the supply of butadiene is insufficient. May lead to

It is known that butadiene can be obtained by dehydrogenation of n-butane in the presence of a catalyst. For example, Patent Document 1 discloses a method for producing butadiene by dehydrogenating butane at a temperature of 620 ° C. and a pressure of 0.02 MPa using Cr ₂ O ₃ / Al ₂ O ₃ as a catalyst. It is disclosed. In Patent Document 2, as in Patent Document 1, Cr ₂ O ₃ / Al ₂ O ₃ is used, butane is dehydrogenated in a fluidized bed reaction mode under the conditions of a temperature of 620 to 790 ° C. and a pressure of 100 to 200 mmHg. A method of manufacturing is disclosed. In any of the methods, the catalyst must be regenerated in a very short cycle due to the deactivation of the catalyst due to the formation of coke at high temperatures. For example, considering energy consumption, we want to minimize the number of catalyst regenerations or eliminate the regeneration step. However, the processes disclosed in these documents require a high frequency of catalyst regeneration, which is an economical process. It can not be said. For this reason, a more efficient process is desired from an industrial viewpoint.

  Oxidative dehydrogenation in the presence of oxygen is also disclosed for the purpose of more advantageously proceeding with dehydrogenation of n-butane. For example, Patent Document 3 discloses a method for producing butadiene by using a Ni / Pb / P / K-based catalyst as a heterogeneous catalyst and dehydrogenating butane. However, coexistence of oxygen not only complicates the process, but also makes it very difficult to obtain the high selectivity necessary for efficient use of raw materials and efficient product separation steps. It is.

  Patent Documents 4 to 6 disclose a two-stage reaction method in which n-butane raw material is dehydrogenated to produce n-butene, and then n-butene is oxidatively dehydrogenated to produce butadiene. A known method can be applied to each stage, but the process becomes long and cannot be said to be an economically effective production method.

  Patent Document 7 discloses a method for producing diolefins from a olefin raw material that coexists with steam using a commercially available Styromax Plus (Sud) or Hypercat GV (Criterion) dehydrogenation catalyst under reduced pressure conditions of 200 to 800 mbar. Is disclosed. Although it has been described that butadiene can be produced from butane in a similar manner, a high yield of butadiene can be obtained by applying the above-mentioned commercially available catalyst to the dehydrogenation reaction of butane which is less reactive. Not only can this be done, but the raw material must also have a high concentration of n-butene.

GB794089 specification GB777380 specification EP16853 Specification US7034195B2 specification US7482500B2 specification US7488857B2 specification US201202817 specification

In the conventional method for producing butadiene, when a C4 fraction containing n-butene is used as a raw material, the acquisition of the raw material is a problem. When n-butane is used as a raw material, the production process is as follows. Improvements are still desired, not at a level that can withstand the industrial scale.
The present invention has been made in view of the above prior art, and aims to provide an industrially advantageous method for producing a product containing butadiene from a raw material containing n-butane by a one-stage dehydrogenation reaction. To do.

  When butadiene is produced from n-butane by a one-step reaction, it generally has two problems due to thermodynamic limitations. The first is a low butadiene equilibrium yield and the second is a decrease in reaction temperature due to a large endotherm.

  Using raw materials that contain more n-butane makes it more difficult to solve these problems. In order to solve these problems, it has been necessary to carry out the reaction under high-temperature and low-pressure conditions so far, so that it is necessary to frequently perform catalyst regeneration, which complicates the process and is not economically successful.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have determined that the total amount of n-butane and n-butene is a specific amount, uses a specific amount of steam, and further uses a specific pressure. It was found that a product containing butadiene which is industrially useful can be produced by carrying out the reaction at. The present invention relates to the following [1] to [10], for example.

[1]
a method in which a raw material containing n-butane is brought into contact with a dehydrogenation catalyst charged in one or more adiabatic reactors to perform a dehydrogenation reaction,
The reactor outlet pressure on the most downstream side is 0.01 or more and less than 0.1 MPa,
The mole ratio of the hydrocarbon having 4 carbon atoms and the steam (steam / hydrocarbon having 4 carbon atoms) in the reactor feed component at the most upstream reactor inlet is 1 to 16,
Butadiene whose total amount of n-butane and n-butene is 40 mol% or more when the total amount of hydrocarbons having 4 carbon atoms in the reactor feed component at the most upstream reactor inlet is 100 mol% A method for producing a product comprising:

[2]
The method for producing a product containing butadiene according to [1], wherein the outlet temperature of the most downstream reactor is 350 to 600 ° C.

[3]
As described in [1] or [2], the mass space velocity (WHSV) of the hydrocarbon having 4 carbon atoms in the reactor feed component at the most upstream reactor inlet is 0.1 to 50 h ⁻¹ with respect to the catalyst. A method for producing a product comprising butadiene.

[4]
The method for producing a product containing butadiene according to any one of [1] to [3], wherein the dehydrogenation catalyst is a catalyst obtained by supporting zinc and a Group VIIIA metal on a silicate support.

[5]
The method for producing a product containing butadiene according to [4], wherein the silicate support is a silicate obtained by removing at least a part of boron atoms from a borosilicate.

[6]
The method for producing a product containing butadiene according to any one of [1] to [5], wherein at least a part of the product obtained from the most downstream reactor outlet is circulated to the upstream reactor. .

[7]
The butadiene according to any one of [1] to [6], wherein at least one butene selected from n-butene and isobutene is separated from the product obtained from the most downstream reactor outlet. Product manufacturing method.

[8]
Separating a C 4 hydrocarbon fraction containing butadiene from the product obtained from the most downstream reactor outlet;
The method according to any one of [1] to [7], including a step of separating a fraction containing butadiene having a higher concentration than the hydrocarbon fraction having 4 carbon atoms from the hydrocarbon fraction having 4 carbon atoms. A method for producing a product containing butadiene.

[9]
A plurality of the reactors connected in series, and the butadiene containing butadiene according to any one of [1] to [8], wherein the flow at the reactor outlet of each stage is heated and fed to the next stage reactor. Manufacturing method.

[10]
Any one of [1] to [9], wherein the reactor is a plurality of reactors, and the dehydrogenation catalyst charged in the remaining reactors is regenerated while performing a dehydrogenation reaction in a part of the reactors. A method for producing a product comprising butadiene according to claim 1.

  The present invention provides a method capable of economically producing a product containing butadiene by a one-stage dehydrogenation reaction using an inexpensive and readily available raw material containing butane.

It is a flowchart figure which shows the one aspect | mode of the manufacturing method of this invention. It is a flowchart figure which shows an aspect different from FIG. 1 of the manufacturing method of this invention.

Next, the present invention will be specifically described.
The method for producing a product containing butadiene according to the present invention is a method in which a raw material containing n-butane is brought into contact with a dehydrogenation catalyst charged in one or more adiabatic reactors to perform a dehydrogenation reaction, which is most downstream. The reactor outlet pressure on the side is 0.01 or more and less than 0.1 MPa, and the molar ratio of the hydrocarbon having 4 carbon atoms and the steam in the reactor feed component at the most upstream reactor inlet (steam / carbon number) N-butane and n- when the total amount of hydrocarbons having 4 carbon atoms in the reactor feed component at the most upstream reactor inlet is 100 mol%. The total amount with butene is 40 mol% or more.
The process for producing a butadiene-containing product of the present invention includes steam as a reactor feed component. For this reason, it is possible to reduce the partial pressure of the reactant such as n-butane.

[material]
In the production method of the present invention, a raw material containing n-butane is used. As a raw material of the present invention, n-butane may be used alone, or a mixture with other compounds may be used as a raw material.

  In the case of using a mixture as a raw material, examples of other compounds include compounds having 4 carbon atoms other than n-butane, preferably hydrocarbons having 4 carbon atoms. Examples of the hydrocarbon having 4 carbon atoms include isobutane, 1-butene, 2-cis-butene, 2-trans-butene and isobutene.

  When a mixture is used as a raw material, at least one hydrocarbon having 4 carbon atoms selected from isobutane, 1-butene, 2-cis-butene, 2-trans-butene and isobutene is used as a compound other than n-butane. Is preferably included.

  When n-butane is used alone as a raw material, it is derived from natural gas, liquefied petroleum gas (LPG), a hydrocarbon fraction having 4 carbon atoms in a petrochemical plant, or a hydrocarbon fraction having 4 carbon atoms in an oil refinery plant. Can be obtained by separation and purification.

When a mixture is used as the raw material, the LPG or a hydrocarbon fraction having 4 carbon atoms can be used as it is.
As a hydrocarbon fraction having 4 carbon atoms, for example, from a hydrocarbon fraction having 4 carbon atoms called raffinate-1, raffinate-2 or raffinate-3 obtained from a naphtha pyrolysis furnace, from a fluid catalytic cracker (FCC) Examples thereof include a hydrocarbon fraction having 4 carbon atoms to be obtained.

Moreover, as a raw material, you may mix and use the above-mentioned thing in arbitrary ratios.
Furthermore, as a raw material, compounds other than n-butane and a C4 compound (however, except n-butane) may be contained. Examples of compounds other than n-butane and compounds having 4 carbon atoms (excluding n-butane) include hydrocarbons having 4 carbon atoms. Specifically, light boiling components such as methane, ethane, ethylene, propane, propylene, n-pentane, n-pentene, n-hexane, n-hexene, n-heptane, n-heptene, isopentane, isopentene, 2- Examples thereof include hydrocarbons having 5 or more carbon atoms such as methylpentane, 2-methylpentene, 3-methylpentane, and 2,2-dimethylbutane.

[Reactor feed components]
The components supplied to the reactor in the production method of the present invention, that is, the reactor feed components will be described.

  As the reactor feed component, for example, the raw material, steam, hydrogen, nitrogen, carbon monoxide, carbon dioxide, and at least a part of the product obtained from the most downstream reactor outlet are circulated to the upstream reactor. In this case, the product obtained from the outlet of the reactor or at least a part of the residue after separating and purifying butadiene from the product can be mentioned.

  In the production method of the present invention, raw materials and steam are usually essential components as the reactor feed component, and the product obtained from the most downstream reactor outlet or butadiene is separated and purified from the product. The other components such as at least a part of the residue after being processed are optional components.

In the present invention, a line for circulating at least a part of the product obtained from the most downstream reactor outlet to the upstream reactor is also called a circulation line.
In the production method of the present invention, the effect of the present invention can be achieved whether or not at least a part of the product obtained from the most downstream reactor outlet is circulated to the upstream reactor. Although it can, it is preferable to circulate.

  In the case of the circulation, a part of the obtained product may be circulated as it is. Usually, after separating and purifying butadiene from the product (butadiene), a part or all of the remaining portion is removed from the reactor. Recycle by recycling. The component circulated in the reactor usually contains at least one of an unreacted raw material and a component generated by a dehydrogenation reaction.

  In the production method of the present invention, the total amount of n-butane and n-butene when the total amount of hydrocarbons having 4 carbon atoms in the reactor feed component at the most upstream reactor inlet is 100 mol%. Is 40 mol% or more. Here, examples of n-butene include 1-butene, 2-cis-butene, and 2-trans-butene. Hereinafter, n-butane and n-butene are collectively referred to as n-C4.

  In the production method of the present invention, butadiene is obtained by dehydrogenation reaction of n-butane, and n-butene is produced as an intermediate. When the product contains n-butene as an intermediate, it is preferable to circulate n-butene through a circulation line and use it as a reactor feed component. The aspect containing n-butene is preferable from the viewpoint of achieving the effect of the present application. This is because the presence of n-butene is thermodynamically advantageous for the production of butadiene. Therefore, it is preferable to include n-butene in the hydrocarbon having 4 carbon atoms in the reactor feed component or to increase the concentration of n-butene in the reactor feed component.

  Specifically, in the present invention, n-butane and n-butene when the total amount of hydrocarbons having 4 carbon atoms in the reactor feed component at the most upstream reactor inlet is 100 mol%. The total amount is 40 mol% or more, preferably 50 mol% or more, more preferably 60 mol% or more.

  In the production method of the present invention, by setting the total amount of n-butane and n-butene in the above range, even when n-butene is not included in the reactor feed component, n-butane and n-butene are included. Even in this case, a product containing butadiene can be produced efficiently.

  In the present invention, the product containing butadiene is usually carbon obtained through a separation and purification process for a product taken out from the outlet of the downstream reactor and a product taken out from the outlet of the most downstream reactor. This refers to a fraction containing a hydrocarbon of formula 4 as a main component (hereinafter also referred to as C4 fraction) or a butadiene product having a higher butadiene concentration obtained from the C4 fraction through further separation and purification steps. At this time, in order to enable separation and purification economically, it is preferable that the value of the butadiene concentration in the product taken out from the outlet of the most downstream reactor or the C4 fraction is high. The butadiene concentration when the amount of the fraction is 100 mol% is industrially required to be 20 mol% or more. From the viewpoint of reducing the separation and purification load, the butadiene concentration is more preferably 30% or more. When the total amount of n-butane and n-butene is less than 40 mol%, it becomes difficult to obtain a butadiene concentration that enables economical separation and purification from the reactor outlet.

  The mixing ratio of n-butane and n-butene in the reactor feed component at the most upstream reactor inlet is not particularly limited. When the total of n-butane and n-butene is 100 mol%, a butadiene that satisfies the industrially required butadiene concentration even when n-butane is 100 mol% and n-butene is 0 mol% is used. A product containing can be produced. From the viewpoint of alleviating the endothermic reaction, it is preferable to include n-butene in the reactor feed component. In the production method of the present invention, since the reaction for obtaining butadiene from n-butane is an endothermic reaction, the thermal load can be increased when the concentration of n-butane in the reactor feed component is high. In addition, it is preferable to include n-butene from the viewpoint of further increasing the concentration of butadiene in the product taken out from the outlet of the most downstream reactor or the C4 fraction, for example, 30 mol% or more. Specifically, the blending ratio of n-butane and n-butene is, when the total amount of n-butane and n-butene is 100 mol%, n-butane exceeds 0 mol% and is 70 mol% or less. It is preferably 20 to 70 mol%, more preferably 30 to 70 mol%, and particularly preferably 40 to 70 mol%.

(steam)
In the production method of the present invention, steam, that is, water vapor is supplied to the reactor.
By supplying steam, i) it is possible to reduce the partial pressure of n-C4 (n-butane and n-butene) in the reactor, and ii) it is possible to mitigate temperature drop due to endothermic reaction. is there. Specifically, i) Steam creates a reaction diluent that is the same as when the reaction system is depressurized. As a result, the partial pressure of the raw material is lowered, and the yield of butadiene is improved thermodynamically. In addition, ii) the presence of steam mitigates a decrease in reaction temperature due to endothermic reaction, and creates a favorable process condition.

As another effect, iii) Coexistence of steam may bring about an effect of suppressing coke formation, particularly in a catalyst system in which coke formation causes deactivation.
From the above viewpoints, in particular, from the viewpoints of i) and ii), in the production method of the present invention, the molar ratio of the hydrocarbon having 4 carbon atoms and the steam in the reactor feed component at the most upstream reactor inlet. (Steam / C4 hydrocarbon) is 1 to 16, preferably 2 to 12, and more preferably 2 to 8.

  If the amount of steam is less than the above range, the pressure in the reaction system must be lowered in order to reduce the partial pressure of the raw material, and the temperature drop due to endothermic reaction becomes large, making it difficult to construct a process. Also, if there is too much steam, the manufacturing cost increases and the process may become uneconomical.

  In addition to making the total amount of n-butane and n-butene a specific amount when the total amount of hydrocarbons having 4 carbon atoms is 100 mol%, the steam is compared with the hydrocarbons having 4 carbon atoms. By prescribing the specific amount, it is possible to create an environment in which the raw material partial pressure is appropriate within the range of the combination of both conditions.

[catalyst]
The dehydrogenation catalyst used in the production method of the present invention will be described.
The catalyst used in the present invention is not particularly limited as long as it can generate butadiene from n-C4 by a dehydrogenation reaction.

  In the production method of the present invention, steam is supplied into the reactor as described above, and the dehydrogenation reaction is performed under reduced pressure conditions. For this reason, in order to ensure productivity, it is necessary to increase the flow rate of the reactor feed component. However, in this case, the contact time between the reactor feed component and the catalyst is relatively short.

Therefore, in order to ensure sufficient butadiene productivity in such a case, it is preferable to use a catalyst having high catalytic activity and excellent steam resistance.
Examples of such a catalyst include a catalyst obtained by supporting zinc and a Group VIIIA metal on a silicate support. The Group VIIIA metal is an old IUPAC system notation, which is a Group 8 to 10 metal in the IUPAC system. Examples of the Group VIIIA metal include platinum, palladium, ruthenium, iridium and rhodium. Among these, platinum is preferable from the viewpoint of catalytic activity. As the metal supported together with zinc, as long as it is a Group VIIIA metal, one kind may be used alone, or two or more kinds may be used in combination.

  The amount of zinc supported on the silicate support is preferably 0.01 to 15% by mass with respect to the entire catalyst (100% by mass) from the viewpoint of catalyst life and catalyst efficiency, and preferably 0.05 to 5%. It is more preferable that it is mass%, and it is especially preferable that it is 0.1-3 mass%. In addition, the amount of the Group VIIIA metal supported on the silicate support is preferably 0.01 to 5% by mass with respect to the total catalyst (100% by mass) from the viewpoint of catalyst life and catalyst efficiency. More preferably, the content is 0.05 to 3% by mass, and particularly preferably 0.1 to 1.5% by mass. The said carrying amount means the ratio with respect to the mass of the whole catalyst of the said mass at the time of expressing the mass of the metal compound used for carrying | support in metal atom conversion. The amount of the metal supported in the catalyst can be directly measured, for example, by an analysis method using ICP.

  Zinc and the Group VIIIA metal preferably have a metal molar ratio (Zn / VIIIA) of 0.5 or more. If it is less than 0.5, the catalyst life is short, and if it is too high, the activity becomes low and the by-products increase. Usually, it is 0.5-50, Preferably it is 1-30, More preferably, it is 1-20.

  It is preferable that the silicate carrier is a silicate obtained by removing at least a part of boron atoms from a borosilicate. Such a catalyst is disclosed, for example, in International Publication No. 2012-20743. Here, the borosilicate is not particularly limited as long as it is a silicate containing a boron atom. Some of such borosilicates have a crystalline type and an amorphous type structure. From the viewpoint of catalytic reaction efficiency and catalyst life, crystalline borosilicate is preferable.

  Crystalline borosilicate has a zeolite structure, and examples of the structure of zeolite include MFI type, BEA type, MWW type, CON type, and FAU type. Among these, MFI-type zeolite (borosilicate) is preferable because it is easily available.

  The aluminum content in the crystalline borosilicate used in the present invention is not particularly limited, but the silica / alumina ratio in the borosilicate is preferably 100 or more, more preferably 500 or more, and 1000 or more. Is more preferably 2000 or more, and usually 400000 or less, which is the limit of the real analysis system.

  When the aluminum content in the crystalline borosilicate is too large, the oligomerization reaction of the unsaturated hydrocarbon that is a product in the production method of the present invention proceeds, the oligomer accumulates on the catalyst as coke, and the catalyst life May become shorter.

Further, the content of the boron atom contained in the borosilicate before removing at least a part of the boron atom is not particularly limited, but is preferably 100 to 30000 ppm, more preferably 500 to 10000 ppm, and particularly preferably 1000 to 8000 ppm. . Lattice defects formed by removing boron atoms are thought to contribute to the long catalyst life of the catalyst, so the borosilicate before removing boron atoms contains a certain amount of boron. Preferably it is. In addition, it is considered that this lattice defect greatly contributes to improvement of dispersibility in the catalyst of zinc and a Group VIIIA metal described later (suppression of metal aggregation) and leads to improvement of catalyst life. The boron atom content can be measured, for example, by an analysis method using ICP (inductively coupled plasma) (ICP-AES).
The borosilicate may be used alone or in combination of two or more.

  The boron atom remaining rate in the silicate after removing at least part of the boron atoms from the borosilicate is the entire boron atoms contained in the borosilicate before removing the boron atoms from the viewpoint of improving the catalyst life. The amount (100% by mass) is preferably 80% by mass or less, more preferably 50% by mass or less, particularly preferably 30% by mass or less, and most preferably 20% by mass or less. The boron atom residual rate can be calculated by comparing the boron atom content in the borosilicate before removing the boron atom and the boron atom content in the silicate after removing the boron atom. .

  The borosilicate described above can be easily produced by a known method, and can also be obtained from a catalyst manufacturer. Moreover, the removal method of the boron atom from a borosilicate can be performed by a well-known method (for example, international publication 2012-20743).

  Also obtained by contacting the zeolite support (A ′) with at least one compound selected from alkali metal hydroxides, alkaline earth metal hydroxides, ammonium hydroxide, ammonia, organic amines, and ammonium salts. It is also possible to use a catalyst in which zinc and a Group VIIIA metal are supported on the zeolite support (A). Such a catalyst is disclosed in, for example, JP2013-163647A.

  These catalysts may be used by filling the reactor in the form of fine powder, but may be used after molding in order to prevent an increase in pressure loss. Shapes to be molded include tablets (Tablets), extruded shapes (Extrusions), pellets (Pellets), spheres / small spheres (Spheres, Micro spheres), CDS extruded shapes (CDS Extractions), trilobes (Trilobes), and quadrobes. (Quadrobes), ring (Ring), 2 spoke ring (2 Spokes rings), special spoke rings such as HGS, EW, LDP, rib rings (Rib rings), and crushed (Granules).

[Reaction conditions]
The reaction conditions in the production method of the present invention will be described.
In the production method of the present invention, when a reactor feed component such as a raw material containing n-butane is brought into contact with the above-described dehydrogenation catalyst, a dehydrogenation reaction of n-C4 proceeds to produce a product containing butadiene. can get.

  In the production method of the present invention, one or a plurality of adiabatic reactors are used, and the pressure at the most downstream reactor outlet that affects the butadiene concentration in the resulting product (hereinafter, all pressures are absolute pressures). ) Is set to 0.01 or more and less than 0.1 MPa. The pressure is preferably from 0.01 to 0.08 MPa, and more preferably from 0.01 to 0.05 MPa.

  When the pressure is higher than the above range, the concentration of butadiene in the product tends not to be sufficient, and when the pressure is lower than the above range, an economical process is not achieved. Therefore, the above range is preferable.

  In the production method of the present invention, one or a plurality of adiabatic reactors are used, and the outlet temperature of the most downstream reactor that affects the butadiene concentration in the obtained product is 350 to 600 ° C. Is preferable, 400 to 600 ° C is more preferable, 450 ° C to 600 ° C is particularly preferable, and 450 to 580 ° C is most preferable.

  If the temperature is lower than the above range, the butadiene concentration in the product tends not to be sufficient, and if the temperature is higher than the above range, the temperature at the reactor inlet is increased in consideration of the temperature decrease due to endothermic reaction, or A lot of reactors must be used, which is not preferable from the viewpoint of catalyst life and process.

By performing the reaction under the mild reaction temperature conditions as described above, it is possible to lengthen the catalyst regeneration cycle, which is advantageous for economical process construction.
The production method of the present invention is usually carried out in the gas phase, and it is preferable to carry out the dehydrogenation reaction in a continuous reactor. In that case, for the purpose of easily grasping the amount of the catalyst used, it is easy to express the mass space velocity (WHSV) based on the mass of the hydrocarbon having 4 carbon atoms in the reactor feed component in contact with the catalyst. Yes and appropriate.

In the production method of the present invention, the mass space velocity (WHSV) of the hydrocarbon having 4 carbon atoms in the reactor feed component at the most upstream reactor inlet to the catalyst (the number of carbon atoms per unit amount of catalyst and unit time). 4) is preferably 0.1 to 50 h ⁻¹ , more preferably 0.1 to 20 h ⁻¹ , and particularly preferably 0.5 to 12 h ⁻¹ .

  If the speed is lower than the above range, the concentration of butadiene in the product tends not to be sufficient. If the speed is higher than the above range, high pressure loss occurs and it is difficult to construct an economical process.

[Reaction format]
The reaction format in the production method of the present invention will be described.
The reaction format used in the production method of the present invention is not particularly limited, and a known format can be adopted. Examples of the reaction format that can be adopted include reaction formats such as a fixed bed, a moving bed, and a fluidized bed. From the viewpoint of ease of process design, a fixed bed system is preferable.

  In the production method of the present invention, it is necessary to compensate for the endothermic component accompanying the dehydrogenation reaction, which is an endothermic reaction. From the viewpoint of ease of process design, an adiabatic reactor is used. As the adiabatic reactor, one or more adiabatic reactors are used. As another embodiment, a method of directly heating the product in the reactor can be used.

  However, if the temperature drop is too great, the reaction may not proceed as close to the reactor outlet, or even if the reaction proceeds, there is a possibility that butadiene will not be produced sufficiently due to the restriction of thermodynamic equilibrium. . In order to avoid this phenomenon, it is possible to increase the reactor inlet temperature. However, if the temperature is too high, deactivation of the catalyst used may occur. Therefore, it is preferable to connect a plurality of reactors in series, heat the flow at the reactor outlet of each stage, and feed it to the next stage reactor.

  In this case, the number of reactors to be used is preferably 1 to 6 and more preferably 2 to 6 in consideration of the economics of the process and the performance of the catalyst. If the number of reactors is too large, problems such as deterioration of the economics of the process occur, which is not preferable.

  In the production method of the present invention, the above-described dehydrogenation catalyst is used to promote the dehydrogenation reaction. However, when the reaction is performed under high temperature conditions, the catalyst is deactivated due to accumulation of coke or alteration of the catalyst. Therefore, it is necessary to periodically burn the accumulated coke and return the deteriorated catalyst to the original catalyst, that is, to regenerate the dehydrogenation catalyst.

  In the fluidized bed or moving bed reaction mode, the operation of returning the accumulated catalyst to the original catalyst (regeneration of the dehydrogenation catalyst) can be performed outside the reactor without stopping the reaction. In the fixed bed reaction system, the reaction is stopped and unreacted raw materials and products are purged, and then the dehydrogenation catalyst is regenerated.

  Therefore, a method in which the reactor is a plurality of reactors and a dehydrogenation catalyst filled in the remaining reactors is regenerated while performing a dehydrogenation reaction in a part of the reactors. In this method, it is preferable that a reactor that does not perform a dehydrogenation reaction is temporarily disconnected from the reaction flow and the catalyst in the disconnected reactor is regenerated.

  When the catalyst regeneration cycle is short, the dehydrogenation reaction is performed in half of the reactor, and the catalyst regeneration is performed in the other half of the reactor. As the catalyst regeneration cycle becomes longer, the dehydrogenation reaction is performed. It is possible to increase the number of reactors used in the process and to reduce the number of reactors that perform catalyst regeneration. On the other hand, when the regeneration period of the catalyst is sufficiently long, it is preferable that the number of reactors for regenerating the catalyst is one and the dehydrogenation reaction is performed in the remaining reactors.

[Separation process]
The production method of the present invention circulates the product obtained from the most downstream reactor outlet or at least a part of the residue after separation and purification of butadiene from the product to the upstream reactor. It is preferable. Separation and purification of the product obtained from the most downstream reactor outlet includes separation of at least one butene selected from n-butene and isobutene from the product obtained from the most downstream reactor outlet. It is preferable to do.

  In the production method of the present invention, a part or all of the product obtained from the most downstream reactor outlet may be circulated to the upstream reactor without separation and purification. From the viewpoint, it is preferable that the obtained product is appropriately separated and purified and then a part thereof is circulated to the upstream reactor. By recycling a product obtained by separating at least one kind of butene selected from n-butene and isobutene from a product obtained from the most downstream reactor outlet, the raw material can be recycled. On the other hand, when the concentration of butadiene in the product obtained from the most downstream reactor outlet is low, etc., all of them are circulated to the upstream reactor, and the reaction is performed again to increase the butadiene concentration. Good.

  In the production method of the present invention, depending on the composition of the reactor feed components such as raw materials, generally, the product obtained from the most downstream reactor outlet includes steam and the main target product butadiene. And hydrogen, unreacted n-butane, unreacted or newly produced n-butene, isobutane, isobutene, by-produced carbon monoxide, carbon dioxide, methane, ethane, ethylene, propane, propylene, 5 or more carbon atoms Of hydrocarbons.

  Among these compounds contained in the product, compounds that are valuable as products, such as hydrogen, isobutene, ethylene, propylene, and butadiene, which is the object of the present invention, should be separated and purified. Is preferred.

  In the production method of the present invention, the product obtained from the most downstream reactor outlet is separated from hydrocarbon and steam by a known separation method, and then hydrogen, carbon monoxide, carbon dioxide and carbon number of 3 or less. It is preferable that a step of separating a light boiling component composed of a hydrocarbon or the like is performed.

  Under reaction conditions where many hydrocarbons having 5 or more carbon atoms are not produced as a by-product, the product after separation of the light-boiling components is a C4 fraction mainly containing butadiene (a hydrocarbon fraction having 4 carbon atoms). Further, when many hydrocarbons having 5 or more carbon atoms are by-produced, they are separated by a method such as distillation to obtain a C4 fraction containing butadiene.

  In the production method of the present invention, butadiene can be obtained by separating and purifying butadiene from the C4 fraction using the C4 fraction as a buttedene. A part or all of the C4 fraction from which butadiene has been separated can be circulated to the upstream reactor, and the remainder can be made into a product. In addition, a method of further increasing the concentration of butadiene contained in the C4 fraction may be performed. For example, a separation step such as distillation is provided to include a butadiene having a higher butadiene concentration (containing a higher concentration of butadiene than the C4 fraction). Fraction) may be separated. When separated by distillation, the butadiene with a high butadiene concentration mainly contains 1-butene, isobutene, and isobutane as components other than butadiene. The remainder after separation of butadiene from this butadiene is used as the product. Or part or all of it can be circulated to the most upstream reactor. Further, the remaining components from which the butadiene having a high butadiene concentration is separated are mainly n-butane and 2-butene, which can be used as a product as they are, or a part or all of them can be upstream. It is also possible to circulate to the side reactor.

  In the production method of the present invention, a method of separating and purifying butadiene from the C4 fraction or butadiene having a high butadiene concentration by a known method is employed. As a method for obtaining butadiene, for example, a method of extracting and separating using dimethylformamide, acetonitrile or N-methylpyrrolidone as an extraction solvent is preferable. After the butadiene is separated, the remaining components may be used as a product as they are, or may be circulated to the most upstream reactor, or isobutene may be separated by a known reactive distillation method.

  Depending on the purpose, in the distillation, if water or methanol is used in the presence of an acid, it can be separated as isobutyl alcohol or methyl-isobutyl ether which can be easily separated by distillation.

  It is also possible to separate isobutene before separating butadiene. In addition, after separating butadiene, 1-butene can be separated and purified from the remaining components by an ordinary distillation method to obtain a product.

[Circulation]
The production method of the present invention circulates the product obtained from the most downstream reactor outlet or at least a part of the residue after separation and purification of butadiene from the product to the upstream reactor. It is preferable. The upstream reactor is more preferably the most upstream reactor.

  The reaction mechanism when butadiene is produced by the dehydrogenation reaction of n-butane is as follows. First, n-butene is produced as an intermediate by the dehydrogenation reaction of n-butane, followed by the dehydrogenation reaction of n-butene. Is known to generate. When n-butene is contained in the raw material, butadiene is easily generated thermodynamically, and the yield increases.

  In the production method of the present invention, the concentration of n-butene contained in the product may be higher than the concentration of butadiene contained in the product. In this case, if it is not intended to produce n-butene with butadiene, n-butene can be circulated to the reactor. Further, a part of n-butene can be separated and purified as a product, and the rest can be recycled to the upstream reactor.

  Unreacted compounds and by-produced compounds such as n-butane, isobutane, isobutene and other compounds can also be circulated to the upstream reactor together with n-butene. In this case, since n-butane is a raw material, there is no particular problem even if it is circulated completely, but isobutane, isobutene and other compounds may accumulate in the reactor depending on the reaction conditions. In such a case, it is preferable to limit the circulation amount.

  In the present invention, the total amount of n-butane and n-butene is 40 mol% when the total amount of hydrocarbons having 4 carbon atoms in the reactor feed component at the most upstream reactor inlet is 100 mol%. As described above, the kind and amount of the raw material and the product to be circulated are prepared.

  The present inventors use n-butane, which is inexpensive and easily available, and makes the total amount of n-butane and n-butene in the reactor feed component within the above range to perform the dehydrogenation reaction. Thus, it has been found that a product containing butadiene at a concentration that can be economically separated and purified can be produced by a single-stage dehydrogenation reaction. In addition, the present inventors, by adding steam as one of the reactor feed components, induces a butadiene formation reaction in a thermodynamically advantageous direction and alleviates a decrease in reaction temperature due to an endothermic reaction. Made it possible. Furthermore, the yield of butadiene was improved by lowering the partial pressure of the reaction components and performing the reaction under reduced pressure conditions.

  The present inventors have found that by performing a dehydrogenation reaction under these conditions, butadiene can be efficiently produced even when n-butane is used as a raw material. That is, the method of the present invention improves the production method of butadiene, which has been eagerly desired, to an industrial level.

EXAMPLES Next, although an Example is shown and this invention is demonstrated further in detail, this invention is not limited by these.
[Experimental Example 1]
To a stainless steel 1.2 L autoclave having a Teflon inner bag, 371 g of a 22.5 mass% tetrapropylammonium hydroxide aqueous solution, 267 g of distilled water and 23.5 g of boric acid were added and stirred at room temperature for 10 minutes.

Further, 111 g of fumed silica (AEROSIL (registered trademark) R380) was added and stirred at room temperature for 1 day.
Next, the obtained slurry was slowly heated while stirring and reacted at 170 ° C. for 6 days. The product was washed and filtered, then dried at 120 ° C. for 4 hours, and further calcined at 540 ° C. for 6 hours to obtain a powder.

  The obtained powder was put into 3 L of 1 mol / L ammonium nitrate aqueous solution, stirred at 80 ° C. for 3 hours, filtered and washed. The aqueous solution of ammonium nitrate was again treated, and the filtered and washed solid was dried at 120 ° C. for 4 hours and further baked at 540 ° C. for 6 hours to obtain a white powder.

  This white powder was confirmed to have an MFI type crystal structure by X-ray powder diffraction measurement. Moreover, when the composition of the borosilicate having the MFI type structure was quantified by ICP-AES and ICP-MS, the boron atom content was 3200 ppm and the silica / alumina ratio was 200000.

10.0 g of the borosilicate having the MFI type structure containing the boron atom prepared above was placed in a glass flask equipped with a cooling tube. Thereafter, 900 ml of 3N nitric acid aqueous solution was added to the flask, and the temperature was raised to 100 ° C. while stirring. The reaction was allowed to proceed for 18 hours after the water began to reflux.
After 18 hours, the slurry was cooled, filtered through a membrane filter (0.5 μm), and the filter cake was washed with 300 ml of distilled water.

  The above-mentioned treatment (addition of nitric acid aqueous solution, reaction with refluxing water, cooling, filtration and washing of the filter cake with distilled water) was repeated once more on the obtained filter cake, and then the filter cake was treated at 120 ° C. for 4 hours. It was calcined in the air for 6 hours at 540 ° C. for 9.7 g to obtain 9.7 g of silicate (zeolite) from which a part of boron atoms had been removed. The amount of boron atoms in the obtained silicate powder was 400 ppm as determined by ICP-AES.

  To 1 g of the silicate obtained above, 0.33 g of an aqueous solution containing 0.160 g of zinc nitrate hexahydrate was added, and impregnated with zinc ions by the Incipient-Wetness method. After impregnating the solution, the powder was sufficiently mixed, and further fired in air at 120 ° C. for 3 hours and at 500 ° C. for 4 hours to prepare a silicate on which zinc was supported.

To 1 g of the silicate on which zinc was supported, 0.33 g of an aqueous solution containing 0.170 g of chloroplatinic acid hexahydrate was added, and impregnated with platinum ions by the Incipient-Wetness method. After impregnating the solution, the powder was sufficiently mixed and then calcined in air at 120 ° C. for 3 hours and further at 500 ° C. for 4 hours to prepare a silicate catalyst carrying platinum and zinc.
As a result of analyzing the platinum-containing (supported) amount and zinc-containing (supported) amount in the catalyst by ICP-AES, they were 0.64% by mass and 1.72% by mass, respectively.

  0.08 g of the catalyst obtained above was filled in a tubular reactor (SUS tube) having a diameter of 1/2 inch and a total length of 300 mm fitted with an alumina inner tube with an inner diameter of 6 mm, and the void was filled with quartz sand. did.

  The reactor was connected to a flow reactor, and after flowing nitrogen, hydrogen was circulated (20 ml / min), and the temperature was raised to 600 ° C. in an electric furnace. After the internal temperature of the reactor reached 600 ° C., the catalyst was reduced with hydrogen (20 ml / min) and water (1.92 g / h) for 2 hours.

After 2 hours, the temperature in the reactor was set to 550 ° C., and using a mass flow controller, a mixed gas of n-butane and trans-2-butene (molar ratio = 6/4) was 0.25 g / h, and isobutane was 0.00. 074 g / h, water 0.79 g / h, and nitrogen were passed through the reactor at a rate of 120 cc / min to initiate the reaction (WHSV for a hydrocarbon catalyst with 4 carbon atoms = 4 h ⁻¹ ). The reaction pressure was 0.016 MPa. After the start of the reaction, the product after a predetermined time shown in Table 1 below was analyzed by an on-line gas chromatograph.

  The product was quantified by an absolute calibration curve method using a gas chromatograph equipped with a flame ionization detector and a gas chromatograph equipped with a thermal conductivity detector. Table 1 below shows the results of analyzing the product.

Reaction conditions Catalyst: Pt (0.64 wt%) / Zn (1.72 wt%) / Deboronated MFI type borosilicate = 0.08 g
Raw material: n-butane / isobutane / trans-2-butene = 0.46 / 0.31 / 0.23 (molar ratio)
Water / carbon number 4 hydrocarbon (raw material) = 8/1 (molar ratio), nitrogen / carbon number 4 hydrocarbon (raw material) = 56/1 (molar ratio),
Reaction temperature = 550 ° C., pressure = 0.016 MPa, raw material feed rate = 0.32 g / h

  Experimental Example 1 shows an example of the raw material used in the present invention. The total amount of n-butane and n-butene is 69 mol% when the total amount of hydrocarbons having 4 carbon atoms in the reaction components at the reactor inlet is 100 mol%. As a result, a C4 fraction (hydrocarbon having 4 carbon atoms) having a butadiene concentration of about 30 mol% when the amount of the C4 fraction is 100 mol% is obtained, and can be used as it is.

  In addition, although a simulation result is shown in Experimental Example 3, Experimental Example 1 is a model reaction of Experimental Example 3. In either case, an LPG raw material consisting of isobutane and n-butane is used, and n-butene in the product is circulated to the reactor. The n-butene concentrations at the reactor inlet and outlet are both about 30%, and the circulation n-butene flow rate is balanced. As a result, it can be said to be a conversion reaction from n-butane fed as a raw material to butadiene.

[Experimental example 2]
Reaction temperature is 540 ° C., catalyst is 0.167 g, isobutane is not circulated, n-butane is 0.24 g / h, 2-trans-butene is 0.097 g / h, and nitrogen is reacted at a rate of 90 cc / min. The dehydrogenation reaction was carried out in the same manner as in Experimental Example 1 except that it was circulated in the vessel (hydrocarbon component + water partial pressure = 0.020 MPa, WHSV = 2 h ⁻¹ for a hydrocarbon catalyst having 4 carbon atoms). .
Table 2 below shows the results of analyzing the product.

Reaction conditions Catalyst: Pt (0.64 wt%) / Zn (1.72 wt%) / Deboronated MFI type borosilicate = 0.167 g
Raw material: n-butane / trans-2-butene = 0.71 / 0.29 / molar ratio,
Water / carbon number 4 hydrocarbon (raw material) = 8/1 (molar ratio), nitrogen / carbon number 4 hydrocarbon (raw material) = 40/1 (molar ratio),
Reaction temperature = 540 ° C., pressure = 0.020 MPa, raw material feed rate = 0.33 g / h

  Experimental Example 2 shows another example of the raw material used in the present invention. The main component of the raw material is n-butane, but about 29 mol% n-butene is also included. As a result, a C4 fraction (hydrocarbon having 4 carbon atoms) having a butadiene concentration of about 25 mol% when the amount of the C4 fraction is 100 mol% can be obtained and used as it is as a butadiene.

  In addition, although the simulation result is shown in Experimental Example 4, Experimental Example 2 is a model reaction of Experimental Example 4. In both cases, n-butane is used as a raw material, and a part of the product n-butene is circulated to the reactor. The n-butene concentrations at the reactor inlet and outlet are both about 30%, and the circulating intermediate n-butene balances, resulting in a conversion reaction from n-butane to n-butene and butadiene. .

[Experimental Example 3]
In the same manner as in Experimental Examples 1 and 2, butene species (n-butane, isobutane, 1-butene, 2-cis-butene, 2-transbutene, isobutene) were changed in reaction conditions such as temperature, pressure and flow rate. The reaction was performed and the reaction rate was measured. The reaction rate constant of each reaction was calculated | required from the result of the obtained reaction rate, and the reaction simulator was created based on these. It is now possible to simulate pressure loss and temperature drop due to endothermic reaction. Using a simulator, a process for producing butadiene was examined according to the flowchart shown in FIG.

  The simulation is an example using four insulated fixed bed reactors. The total amount of catalyst used in the simulation was 13.6 tons (each reactor was charged 1/4), the bulk density was 0.70 g / ml, and the airspace ratio was 0.46. The diameter of each reactor was 7 m.

  According to FIG. 1, LPG comprising isobutane and n-butane is used as a raw material (isobutane / n-butane = 1/2 molar ratio), and steam (water) and light-boiling components are separated to obtain butadiene [17]. After separation of pure butadiene [21], C4 fraction [23] containing isobutene is used as a product, and n-butene [22] is circulated.

In the flow chart shown in FIG. 1, [1] represents the feed flow of the raw material and water. In addition, four adiabatic reactors ([2], [6], [10], [14]) were used, and the temperature of the flow lowered by the endothermic reaction was changed to heaters [4], [8], and [12]. And heated to a predetermined temperature (570 ° C. in Experimental Example 3). In step [16], water [18] and light boiling component [19] are separated to obtain butadiene [17].
Tables 3 and 4 below show the simulation results of the products.

  Each reactor inlet temperature was constant. The results show a decrease in temperature due to endothermic reaction and a decrease in pressure due to pressure loss. The preferred butadiene yield is obtained by adjusting the pressure and temperature values at the most downstream reactor outlet that most affect the butadiene yield. When the amount of the butadiene [17] (C4 fraction) is 100 mol%, the butadiene concentration is about 30 mol%, which is an economically separable value.

[Experimental Example 4]
A process for producing butadiene was examined in accordance with the flowchart shown in FIG.

[1] to [19] in FIG. 2 are the same as those in FIG. From the C4 fraction [17] obtained after separating the steam (water) and light-boiling components, the fraction [22] containing butadiene [21], n-butane and 2-butene as main components in step [20] [22] ] Is obtained. [22] circulates in the reactor. As for residue [25] obtained after separation of pure butadiene [24] from [21], 75 mol% is circulated to the reactor, and 25 mol% is the product [26] of C4 fraction containing 1-butene. .
The simulation results are shown in Tables 5 and 6 below.

  The butadiene concentration when the amount of the butadiene (C4 fraction) in the stream [21] is 100 mol% is about 30 mol%, which is an economically separable concentration. By circulating a large amount of n-butene, the amount of steam used is reduced.

[Experimental Example 5]
Except that the raw material composition is isobutane / n-butane = 1 / 0.57 molar ratio, the same simulation as in Experimental Example 3 was performed, and the results are shown in Tables 7 and 8 below.

  A preferable butadiene yield can be obtained by adjusting the pressure and temperature values at the rearmost reactor outlet in the same manner as in Experimental Example 3. When the amount of butadiene [17] (C4 fraction) is 100 mol%, the butadiene concentration is about 22 mol%, which is an economically separable value. Incidentally, the total concentration of n-butane and n-butene was 43% in the flow of the reactant at the inlet of the reactor (2).

[Experimental Example 6]
Same as Experimental Example 3 except that the raw material composition is isobutane / n-butane / cis-2-butene / trans-2-butene = 1 / 0.31 / 0.16 / 0.21 mol and no circulation is performed. Simulation and examination.
The simulation results are shown in Tables 9 and 10 below.

  Similar to Experimental Example 3, a favorable butadiene yield can be obtained by adjusting the pressure and temperature values at the rearmost reactor outlet. The butadiene concentration when the amount of butadiene (C4 fraction) was 100 mol% was about 21 mol%, but it is a value that allows economical separation and purification of butadiene. Incidentally, the total concentration of n-butane and n-butene was 40% in the flow of the reactant at the inlet of the reactor (2).

[Comparative Example]
Outside the range of the reaction conditions of the method of the present invention, for example, the pressure is 0.1 MPa or more, the water / carbon number of hydrocarbon is less than 2, and the number of carbon atoms in the reactor feed component at the most upstream reactor inlet is 4 When the total amount of hydrocarbons is 100 mol% and the total concentration of n-butane and n-butene is less than 40 mol%, the amount of butadiene (C4 fraction) is 100 mol%. Since the butadiene concentration was as low as less than 15 mol%, an economical butadiene production process could not be obtained.

Claims (10)

a method in which a raw material containing n-butane is brought into contact with a dehydrogenation catalyst charged in one or more adiabatic reactors to perform a dehydrogenation reaction,
The reactor outlet pressure on the most downstream side is 0.01 or more and less than 0.1 MPa,
The mole ratio of the hydrocarbon having 4 carbon atoms and the steam (steam / hydrocarbon having 4 carbon atoms) in the reactor feed component at the most upstream reactor inlet is 1 to 16,
Butadiene whose total amount of n-butane and n-butene is 40 mol% or more when the total amount of hydrocarbons having 4 carbon atoms in the reactor feed component at the most upstream reactor inlet is 100 mol% A method for producing a product comprising:   The method for producing a product containing butadiene according to claim 1, wherein the outlet temperature of the most downstream reactor is 350 to 600 ° C. The butadiene according to claim 1 or 2, wherein the mass space velocity (WHSV) of the hydrocarbon having 4 carbon atoms in the reactor feed component at the most upstream reactor inlet with respect to the catalyst is 0.1 to 50 h ^-1. A method for producing a product comprising:   The method for producing a product containing butadiene according to any one of claims 1 to 3, wherein the dehydrogenation catalyst is a catalyst obtained by supporting zinc and a Group VIIIA metal on a silicate support.   The method for producing a product containing butadiene according to claim 4, wherein the silicate support is a silicate obtained by removing at least a part of boron atoms from a borosilicate.   The method for producing a product containing butadiene according to any one of claims 1 to 5, wherein at least a part of the product obtained from the most downstream reactor outlet is circulated to the upstream reactor.   A product comprising butadiene according to any one of claims 1 to 6, wherein at least one butene selected from n-butene and isobutene is separated from the product obtained from the most downstream reactor outlet. Manufacturing method. Separating a C 4 hydrocarbon fraction containing butadiene from the product obtained from the most downstream reactor outlet;
The butadiene as described in any one of Claims 1-7 which has the process of isolate | separating the fraction containing a butadiene of a higher density | concentration than the said C4 hydrocarbon fraction from the said C4 hydrocarbon fraction. A method for producing a product comprising:   A plurality of the reactors are connected in series, and the flow at the outlet of the reactor of each stage is heated and fed to the next stage reactor. The product containing butadiene according to any one of claims 1 to 8 Production method.   The reactor is a plurality of reactors, and the dehydrogenation catalyst charged in the remaining reactors is regenerated while performing the dehydrogenation reaction in some of the reactors. A method for producing a product containing butadiene as described in 1.

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