JP2023031583A - Manufacturing method of 1,3-butadiene and manufacturing device of 1,3-butadiene - Google Patents

Abstract

To provide a manufacturing method of 1,3-butadiene capable of continuously manufacturing 1,3-butadiene with a high yield, and capable of suppressing of the occurrence of a by-product and a manufacturing device of the 1,3-butadiene.SOLUTION: There is provided a method for manufacturing 1,3-butadiene in which 1,3-butadiene is continuously produced from a raw material gas containing ethanol, acetaldehyde, and an inert gas. The method includes a conversion step of bringing the raw material gas into contact with a catalyst layer containing a catalyst and converting ethanol and acetaldehyde in the raw material gas to 1,3-butadiene. A content of inert gas in the raw material gas is 5 to 50 vol.% with respect to a total volume of the raw material gas.SELECTED DRAWING: None

Description

The present invention relates to a method for producing 1,3-butadiene and an apparatus for producing 1,3-butadiene.

Butadiene such as 1,3-butadiene is used as a raw material for styrene-butadiene rubber (SBR) and the like. As a method for producing 1,3-butadiene, for example, a method of converting ethanol to acetaldehyde in the presence of a catalyst and then converting ethanol and acetaldehyde to 1,3-butadiene is known (see, for example, Patent Document 1 reference).

Japanese Patent Publication No. 2017-532318

In the technique of Patent Document 1, the reaction is performed using high-concentration ethanol of 80% by mass or more as a raw material. In addition, when a catalyst with high reaction activity (catalytic activity) is used, the amount of ethanol and acetaldehyde in the gas composition after the reaction is less than before, and the amount of by-products is more than before. These by-products dissolve in ethanol and acetaldehyde when they coexist and flow through the piping.
However, if ethanol or acetaldehyde does not coexist, or if the concentration of ethanol or acetaldehyde is low, the above-mentioned by-products will adhere to analytical instruments, piping, etc. in the manufacturing process, resulting in failure of analytical instruments, clogging of piping, and pressure loss. It may be the cause.

Also, the conversion reaction of ethanol and acetaldehyde to 1,3-butadiene is known to be an endothermic reaction. When a catalyst with high reaction activity is used and high-concentration ethanol is used as a raw material to perform the above conversion reaction, the temperature of the catalyst layer containing the catalyst drops due to the large amount of heat absorption, resulting in a drop in catalytic activity. Therefore, there is concern that the yield of 1,3-butadiene will decrease.

Accordingly, the present invention provides a method for producing 1,3-butadiene that can continuously produce 1,3-butadiene at a high yield and suppress the generation of by-products, and a method for producing 1,3-butadiene. It is intended for manufacturing equipment.

In order to solve the above problems, the present invention has the following aspects.
[1] A method for producing 1,3-butadiene in which 1,3-butadiene is continuously produced from a raw material gas containing ethanol, acetaldehyde, and an inert gas,
A conversion step of contacting the raw material gas with a catalyst layer containing a catalyst to convert ethanol and acetaldehyde in the raw material gas to 1,3-butadiene,
A method for producing 1,3-butadiene, wherein the content of the inert gas in the raw material gas is 5 to 50% by volume with respect to the total volume of the raw material gas.
[2] 1 according to [1], wherein the total amount of the ethanol content and the acetaldehyde content in the raw material gas is 40 to 95% by volume with respect to the total mass of the raw material gas. , 3-butadiene production method.
[3] The method for producing 1,3-butadiene according to [1] or [2], further comprising a dilution step of diluting the gas containing ethanol and acetaldehyde with the inert gas.
[4] Any one of [1] to [3], wherein the ratio of the content of ethanol in the source gas to the content of acetaldehyde in the source gas (ethanol/acetaldehyde ratio) is 1 to 100. A method for producing 1,3-butadiene as described.
[5] The method for producing 1,3-butadiene according to any one of [1] to [4], wherein the catalyst layer has a thermal conductivity of 0.1 to 250 W/m·K.
[6] The catalyst layer contains a diluent,
The method for producing 1,3-butadiene according to any one of [1] to [5], wherein the diluent has a higher thermal conductivity than the catalyst.

[7] A 1,3-butadiene production apparatus for continuously producing 1,3-butadiene,
a conversion means and a purification means;
The conversion means contacts an ethanol-containing gas containing ethanol with a catalyst layer containing a catalyst, converts the ethanol in the ethanol-containing gas into 1,3-butadiene, and converts the ethanol-containing gas into 1,3-butadiene. Equipped with a reactor for producing gas,
The purification means comprises a distillation column for purifying the crude gas obtained by the conversion means,
A connecting pipe that connects the reactor and the distillation column,
The connection pipe has at least one bend,
The apparatus for producing 1,3-butadiene, wherein the curved portion has a radius of curvature of 20 mm or more.
[8] The apparatus for producing 1,3-butadiene according to [7], wherein the inner surface of the connecting pipe has an arithmetic average roughness of 1.02 μm or less.
[9] The apparatus for producing 1,3-butadiene according to [7] or [8], wherein the inner surface of the connecting pipe is coated with an organic compound having 6 to 12 carbon atoms.
[10] The apparatus for producing 1,3-butadiene according to any one of [7] to [9], wherein the connecting pipe has at least one bypass, and the bypass is removable.
[11] The apparatus for producing 1,3-butadiene according to any one of [7] to [10], wherein the catalyst layer has a thermal conductivity of 0.1 to 250 W/m·K.
[12] The catalyst layer contains a diluent,
The apparatus for producing 1,3-butadiene according to any one of [7] to [11], wherein the diluent has a higher thermal conductivity than the catalyst.
[13] The apparatus for producing 1,3-butadiene according to any one of [7] to [12], which has two or more heating means for heating the reactor.
[14] When the length of the catalyst layer in the reactor in the flow direction of the source gas is L,
A first area is defined as a region from the inlet side of the raw material gas to L/3 in the catalyst layer,
A region from the first area to L/3 is defined as a second area,
A region from the second area to L/3 is defined as a third area,
Let k1 be the catalytic activity of the catalyst filled in the first area, and w1 be the total mass of the catalyst filled in the first area,
Let k2 be the catalytic activity of the catalyst filled in the second area, and w2 be the total mass of the catalyst filled in the second area,
When the catalytic activity of the catalyst packed in the third area is k3 and the total mass of the catalyst packed in the third area is w3,
The apparatus for producing 1,3-butadiene according to any one of [7] to [13], which satisfies the following formula (a).
k1×w1<k2×w2<k3×w3 (a)

[15] A 1,3-butadiene production apparatus for continuously producing 1,3-butadiene from a raw material gas containing ethanol, acetaldehyde, and an inert gas,
a conversion means and a purification means;
The conversion means contacts the raw material gas with a catalyst layer containing a catalyst, converts ethanol and acetaldehyde in the raw material gas into 1,3-butadiene, and produces a crude product gas containing the 1,3-butadiene. with a reactor of
The purification means comprises a distillation column for purifying the crude gas obtained by the conversion means,
The content of the inert gas in the raw material gas is 5 to 50% by volume with respect to the total volume of the raw material gas,
A connecting pipe that connects the reactor and the distillation column,
The connection pipe has at least one bend,
The apparatus for producing 1,3-butadiene, wherein the curved portion has a radius of curvature of 20 mm or more.
[16] 1 according to [15], wherein the total amount of the ethanol content and the acetaldehyde content in the raw material gas is 40 to 95% by volume with respect to the total mass of the raw material gas. , 3-butadiene manufacturing equipment.
[17] The 1,3-butadiene of [15] or [16], further comprising a diluting device that dilutes the intermediate gas containing the ethanol and the acetaldehyde with the inert gas before the reactor. Manufacturing equipment.
[18] The apparatus for producing 1,3-butadiene according to any one of [15] to [17], wherein the inner surface of the connecting pipe has an arithmetic mean roughness of 1.02 μm or less.
[19] The apparatus for producing 1,3-butadiene according to any one of [15] to [18], wherein the inner surface of the connecting pipe is coated with an organic compound having 6 to 12 carbon atoms.
[20] The apparatus for producing 1,3-butadiene according to any one of [15] to [19], wherein the connecting pipe has at least one bypass, and the bypass is removable.
[21] The apparatus for producing 1,3-butadiene according to any one of [15] to [20], wherein the catalyst layer has a thermal conductivity of 0.1 to 250 W/m·K.
[22] the catalyst layer comprises a diluent;
The apparatus for producing 1,3-butadiene according to any one of [15] to [21], wherein the diluent has a higher thermal conductivity than the catalyst.
[23] The apparatus for producing 1,3-butadiene according to any one of [15] to [22], which has two or more heating means for heating the reactor.
[24] When the length of the catalyst layer in the reactor in the flow direction of the source gas is L,
A first area is defined as a region from the inlet side of the raw material gas to L/3 in the catalyst layer,
A region from the first area to L/3 is defined as a second area,
A region from the second area to L/3 is defined as a third area,
Let k1 be the catalytic activity of the catalyst filled in the first area, and w1 be the total mass of the catalyst filled in the first area,
Let k2 be the catalytic activity of the catalyst filled in the second area, and w2 be the total mass of the catalyst filled in the second area,
When the catalytic activity of the catalyst packed in the third area is k3 and the total mass of the catalyst packed in the third area is w3,
The apparatus for producing 1,3-butadiene according to any one of [15] to [23], which satisfies the following formula (a).
k1×w1<k2×w2<k3×w3 (a)

According to the method for producing 1,3-butadiene and the apparatus for producing 1,3-butadiene of the present invention, it is possible to continuously produce 1,3-butadiene at a high yield and generate by-products. can be suppressed.

1 is a schematic diagram showing part of a 1,3-butadiene production apparatus according to an embodiment of the present invention. FIG. 1 is a schematic diagram of a reactor of a 1,3-butadiene production apparatus according to an embodiment of the present invention. FIG. FIG. 3 is a schematic diagram of a reactor of a 1,3-butadiene production apparatus according to another embodiment of the present invention. FIG. 2 is a schematic diagram showing the entire apparatus for producing 1,3-butadiene shown in FIG. 1. FIG. FIG. 5 is a schematic diagram showing a part of the hydrogen concentration reducing device shown in FIG. 4;

In the present specification, a numerical range represented by "-" indicates a numerical range including numerical values before and after "-" as lower and upper limits.

[Method for producing 1,3-butadiene]
The method for producing 1,3-butadiene of the present invention is a method for continuously producing 1,3-butadiene from a raw material gas containing ethanol, acetaldehyde and an inert gas. In addition, the method for producing 1,3-butadiene of the present invention reduces the amount of ethanol and acetaldehyde in the source gas for the purpose of suppressing the effect of reduced reactivity or by-products caused by using a catalyst with high reaction activity. A method for continuously producing 1,3-butadiene characterized by:
The method for producing 1,3-butadiene of the present invention has a conversion step of contacting a raw material gas with a catalyst layer containing a catalyst to convert ethanol and acetaldehyde in the raw material gas into 1,3-butadiene.

The raw material gas essentially contains ethanol, acetaldehyde, and an inert gas. The source gas may contain other components such as water and hydrogen. Further, the source gas may be a gas containing an inert gas in an intermediate gas containing ethanol and acetaldehyde, which has undergone a step of converting a part of ethanol from an ethanol-containing gas containing ethanol into acetaldehyde.

Ethanol is not particularly limited, and may be, for example, ethanol derived from fossils such as shale gas and petroleum, or bioethanol derived from biomass such as plants, animals, and garbage. Among them, bioethanol is preferable because it contains few impurities such as nitrogen compounds and sulfur compounds and the catalyst is less likely to deteriorate.

Acetaldehyde may be obtained using the production apparatus 100 described later, or may be obtained from the outside. Since 1,3-butadiene can be efficiently produced, it is preferable to use acetaldehyde obtained using the production apparatus 100 described later.

The inert gas can be any gas that does not adversely affect the conversion reaction that converts ethanol and acetaldehyde to 1,3-butadiene. Examples of the inert gas include rare gases such as nitrogen gas and argon gas, and carbon dioxide. Among these, nitrogen gas and argon gas are preferred, and nitrogen gas is more preferred, from the viewpoint of price and availability. The inert gas may be used singly or in combination of two or more.

The content of the inert gas in the source gas is 5 to 50% by volume, preferably 5 to 40% by volume, more preferably 5 to 30% by volume, relative to the total volume of the source gas. When the content of the inert gas in the raw material gas is at least the above lower limit, generation of by-products can be suppressed. In addition, when the content of the inert gas in the raw material gas is at least the above lower limit, the separation of the inert gas after the reaction can be facilitated. When the content of the inert gas in the raw material gas is equal to or less than the above upper limit, it is possible to suppress a decrease in the yield of 1,3-butadiene.

The total amount of the ethanol content and the acetaldehyde content in the raw material gas (hereinafter also simply referred to as "total amount") is preferably 40 to 95% by volume, preferably 50 to 95% by volume, relative to the total volume of the raw material gas. % by volume is more preferred, 60 to 95% by volume is even more preferred, and 70 to 95% by volume is particularly preferred. When the total amount is at least the above lower limit, the yield of 1,3-butadiene is improved. Generation|occurrence|production of a by-product can be suppressed as a total amount is below the said upper limit.

The ratio of the content of ethanol in the source gas to the content of acetaldehyde in the source gas (ethanol/acetaldehyde ratio) is preferably 1 to 100, more preferably 1 to 50, further preferably 1 to 20, and 1 -10 is particularly preferred, and 1-5 is most preferred. When the ethanol/acetaldehyde ratio is within the above numerical range, the yield of 1,3-butadiene is improved.

The method for producing 1,3-butadiene of the present embodiment preferably has a dilution step of diluting a gas containing ethanol and acetaldehyde (an “intermediate gas” described later) with an inert gas before the conversion step. By including the dilution step, the content of inert gas in the raw material gas can be easily controlled. In addition, by having a dilution step, the concentration of by-products can be diluted even when the conversion of ethanol and acetaldehyde is high. Therefore, adhesion of by-products to the piping can be prevented.
The raw material gas may be obtained by diluting ethanol, or may be obtained by diluting acetaldehyde. Alternatively, an intermediate gas containing ethanol and acetaldehyde obtained by converting part of an ethanol-containing gas containing ethanol into acetaldehyde may be diluted with an inert gas. Furthermore, in the step of generating an intermediate gas, in the case of a conversion step using an ethanol-containing gas diluted with an inert gas, a gas containing ethanol, acetaldehyde, and an inert gas is generated. can also be used as
As another embodiment, by reducing the amount of the source gas without diluting the total amount of the ethanol content and the acetaldehyde content in the source gas with an inert gas, ethanol and acetaldehyde can be converted. Continuous production of 1,3-butadiene can be carried out by suppressing the generation of by-products without lowering the yield.
However, from the viewpoint of further increasing the yield of 1,3-butadiene, it is preferable to obtain the source gas by diluting the gas containing ethanol and acetaldehyde.

The conversion step is a step of contacting the raw material gas with a catalyst layer containing a catalyst to convert ethanol and acetaldehyde in the raw material gas to 1,3-butadiene.
In the conversion step, 1,3-butadiene is obtained by the reaction represented by the following formula (1).
CH ₃ CH ₂ OH+CH ₃ CHO→CH ₂ =CH-CH=CH ₂ +2H ₂ O (1)

In the conversion step, it is preferable to use two or more parallel reactors for the conversion reaction of converting ethanol and acetaldehyde in the feed gas to 1,3-butadiene in the presence of a catalyst. By using two or more parallel reactors, maintenance can be performed on one reactor while the conversion reaction is being performed on the other reactor. Reactor maintenance includes catalyst regeneration and replacement, removal of by-products adhering to the interior of the reactor, and the like.

In the conversion step, the raw material gas is supplied to the reactor, contacted with a catalyst layer containing a catalyst, and the pressure and temperature are adjusted to convert ethanol and acetaldehyde into 1,3-butadiene.

Any catalyst may be used as long as it promotes the conversion reaction of ethanol and acetaldehyde to 1,3-butadiene. That is, any material may be used as long as it has catalytic activity for the conversion reaction. Examples of catalysts include tantalum, zirconium, niobium, hafnium, magnesium, zinc and silicon. Among them, zirconium and hafnium are preferable from the viewpoint of the yield of 1,3-butadiene. As the catalyst, one type may be used alone, or two or more types may be used in combination.
Examples of the mode of using a catalyst include metals, oxides, chlorides, and the like. The mode of using the catalyst includes a mode of using a mixture of two or more of metals, oxides, chlorides, etc., and a mode of using metals, oxides, chlorides, etc., or a mixture thereof on a carrier. An embodiment (supported catalyst) can be exemplified.

As used herein, gas hourly space velocity (GHSV) is obtained by dividing the gas volume flow rate in terms of standard conditions by the volume of the catalyst. The gas hourly space velocity of the raw material gas to the catalyst is preferably 100 to 10000 h ^-1 , more preferably 200 to 8000 h ^-1 and even more preferably 400 to 6000 h ^-1 in terms of standard conditions. When the GHSV is equal to or higher than the lower limit, the raw material gas processing capacity increases. When the GHSV is equal to or less than the above upper limit, the conversion rate of ethanol and acetaldehyde is improved.
The GHSV of the raw material gas is obtained by dividing the flow rate of the raw material gas in terms of the standard state by the catalyst filling amount (the volume of the catalyst layer).

The GHSV of ethanol and acetaldehyde in the raw material gas for the catalyst is preferably 100 to 3000 h ⁻¹ , more preferably 200 to 2500 h ⁻¹ and even more preferably 400 to 2000 h ⁻¹ in terms of standard conditions. When the GHSV is equal to or higher than the lower limit, the raw material gas processing capacity increases. When the GHSV is equal to or less than the above upper limit, the conversion rate of ethanol and acetaldehyde is improved.
The GHSV of ethanol and acetaldehyde in the source gas is obtained by dividing the flow rate of ethanol and acetaldehyde in terms of standard conditions by the amount of catalyst packed (volume of catalyst layer).

The thermal conductivity of the catalyst layer is preferably 0.1 to 250 W/m·K, more preferably 0.15 to 200 W/m·K, even more preferably 0.2 to 100 W/m·K. When the thermal conductivity of the catalyst layer is equal to or higher than the above lower limit, heat from external heating can be easily conducted to the catalyst layer, and a temperature drop due to the conversion reaction can be suppressed. Therefore, the catalytic activity of the catalyst layer is maintained, and the yield of 1,3-butadiene can be increased. When the thermal conductivity of the catalyst layer is equal to or less than the above upper limit, the local temperature rise due to overreaction can be limited to a part, and the generation of by-products can be suppressed.
The thermal conductivity of the catalyst layer can be measured according to the hot wire method (parallel method) described in JIS R2251-2:2007.
When the catalyst layer is formed of only one kind of catalyst, the thermal conductivity of the catalyst layer is the same as the thermal conductivity of the catalyst described below.

The thermal conductivity of the catalyst is preferably 0.01 to 50 W/m·K, more preferably 0.05 to 40 W/m·K, even more preferably 0.1 to 30 W/m·K. When the thermal conductivity of the catalyst is equal to or higher than the above lower limit value, the heat due to heating from the outside is easily transmitted to the catalyst, and the temperature drop due to the conversion reaction can be suppressed. Therefore, the catalytic activity of the catalyst is maintained, and the yield of 1,3-butadiene is increased. If the thermal conductivity of the catalyst is equal to or less than the above upper limit, local temperature rise is prevented, so overreaction is suppressed.
The thermal conductivity of the catalyst can be measured by the same method as the thermal conductivity of the catalyst layer.

The content of the catalyst is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, relative to the total mass of the catalyst layer. When the content of the catalyst is at least the above lower limit, the catalytic activity of the catalyst layer can be enhanced, and the yield of 1,3-butadiene can be enhanced. The upper limit of the catalyst content is not particularly limited, and may be, for example, 100% by mass.

The catalyst layer may contain a diluent. As a diluent, a substance having a higher thermal conductivity than the catalyst is preferred. By containing a diluent having a higher thermal conductivity than the catalyst, the thermal conductivity of the catalyst layer can be further increased. For this reason, the heat generated by heating from the outside is easily conducted to the catalyst layer, and the temperature drop due to the conversion reaction can be suppressed. As a result, the yield of 1,3-butadiene can be increased.
Examples of diluents include alumina balls, zirconia balls, silica balls, silicon carbide, quartz, Raschig rings and the like. As the diluent, those having high thermal conductivity and not inducing side reactions are preferred. Diluents that do not induce side reactions include diluents with low acidity. The acidity of the diluent is preferably 10.0 mmol/mg or less, more preferably 5.0 mmol/mg or less. A method for measuring the acidity of a diluent includes, for example, a method of evaluating the acidity of a solid surface using pyridine as a probe molecule using an infrared spectrophotometer. As the diluent, zirconia balls, silica balls, and silicon carbide are preferable because they have high thermal conductivity and do not induce side reactions.
As used herein, the term "diluent" refers to a substance that does not have catalytic activity for the conversion reaction of ethanol and acetaldehyde to 1,3-butadiene.

The thermal conductivity of the diluent is preferably 0.1 to 300 W/m·K, more preferably 0.15 to 250 W/m·K, even more preferably 0.2 to 200 W/m·K. When the thermal conductivity of the diluent is equal to or higher than the above lower limit, heat due to heating from the outside is easily conducted to the catalyst layer, and temperature drop due to the conversion reaction can be suppressed. Therefore, the catalytic activity of the catalyst layer is maintained, and the yield of 1,3-butadiene can be increased. If the thermal conductivity of the diluent is equal to or less than the above upper limit, local temperature rise is prevented, thereby suppressing overreaction.
The thermal conductivity of the diluent can be measured by the same method as the thermal conductivity of the catalyst layer.

The content of the diluent is preferably 5 to 50% by mass, more preferably 5 to 40% by mass, even more preferably 5 to 30% by mass, relative to the total mass of the catalyst layer. When the content of the diluent is at least the above lower limit, the thermal conductivity of the catalyst layer can be further increased. When the content of the diluent is equal to or less than the above upper limit value, the decrease in catalytic activity of the catalyst layer can be suppressed, and the yield of 1,3-butadiene can be increased.

The pressure (conversion pressure) in the conversion step is, for example, preferably 0 to 1.0 MPaG, more preferably 0 to 0.5 MPaG, even more preferably 0 to 0.3 MPaG. When the conversion pressure is equal to or higher than the above lower limit, the yield of 1,3-butadiene is improved. When the conversion pressure is equal to or less than the above upper limit, it is possible to further suppress the generation of by-products due to excessive reaction.

The temperature in the conversion reaction (conversion temperature) is, for example, preferably 50 to 500°C, more preferably 300 to 400°C, even more preferably 320 to 370°C. When the conversion temperature is at least the above lower limit, the yield of 1,3-butadiene is improved. When the conversion temperature is equal to or lower than the above upper limit, generation of by-products due to excessive reaction can be further suppressed.

The conversion of ethanol and acetaldehyde in the conversion step is preferably greater than 30%, more preferably greater than 40%, even more preferably greater than 50%.
Here, the "conversion rate of ethanol and acetaldehyde" in the conversion step means the ethanol and acetaldehyde consumed in the reactor with respect to the number of moles of ethanol and acetaldehyde in the raw material gas supplied to the reactor per unit time. means the molar ratio of the number of moles per unit time. The number of moles per unit time of ethanol and acetaldehyde consumed in the reactor is the number of moles per unit time of ethanol and acetaldehyde in the raw material gas supplied to the reactor, and the crude product gas discharged from the reactor. It is calculated by subtracting the number of moles per unit time of ethanol and acetaldehyde.

The 1,3-butadiene selectivity of the conversion reaction in the conversion step is preferably greater than 60%, more preferably greater than 70%, and even more preferably greater than 80%. The "1,3-butadiene selectivity" of the conversion reaction in the conversion step refers to the number of moles of ethanol and acetaldehyde consumed in the reactor of the conversion step per unit time, converted to 1,3-butadiene. means the ratio (percentage) of the number of moles of ethanol and acetaldehyde produced per unit time.

The yield of 1,3-butadiene in the conversion reaction in the conversion step is preferably 40-90%, more preferably 50-90%, even more preferably 60-90%. The "yield of 1,3-butadiene" of the conversion reaction in the conversion step means "conversion rate of ethanol and acetaldehyde"×"selectivity of 1,3-butadiene".

Preferably, about 65 to 80 mole percent of the acetaldehyde is converted to 1,3-butadiene in the conversion step.

By-products produced in the conversion process include impurities (heavy substances) contained in the brown oil and impurities (light substances) contained in the crude gas.
Examples of brown oils include hydrocarbons having 5 or more carbon atoms, alcohols having 3 or more carbon atoms, aldehydes having 3 or more carbon atoms, ketones having 2 or more carbon atoms, ethers having 3 or more carbon atoms, esters having 2 or more carbon atoms, Examples thereof include carboxylic acids having 1 or more carbon atoms.
The upper limit of the carbon number of the brown oil is not particularly limited, but is set to 50, for example.

Examples of impurities (light substances) contained in the crude product gas include ethylene, propylene, diethyl ether, ethyl acetate, butanol, hexanol, 1-butene, 2-butene, isobutene, pentene, pentadiene, hexene, and hexadiene. be done.

In the method for producing 1,3-butadiene of the present invention, the content of the inert gas in the raw material gas is set to 5% by volume or more with respect to the total volume of the raw material gas, thereby suppressing the production of by-products. It is possible to suppress adhesion of by-products to piping. In addition, by setting the content of the inert gas in the raw material gas to 50% by volume or less with respect to the total volume of the raw material gas, the unnecessary inert gas after the reaction can be easily separated, and the temperature By suppressing the deterioration of the catalytic activity of the catalyst contained in the catalyst layer due to the deterioration, 1,3-butadiene can be continuously produced at a high yield.
In the method for producing 1,3-butadiene of the present invention, the effects of the present invention can be further enhanced by applying a 1,3-butadiene production apparatus 100A, which will be described later.

[Apparatus for producing 1,3-butadiene]
FIG. 1 shows an example of a 1,3-butadiene production apparatus used in the 1,3-butadiene production method of the present invention.
It should be noted that the dimensions and the like of the drawings illustrated in the following description are examples, and the present invention is not necessarily limited to them, and can be implemented by appropriately changing within the scope of not changing the gist of the present invention. .

As shown in FIG. 1, a 1,3-butadiene production apparatus 100A (hereinafter also simply referred to as “production apparatus 100A”) of the present embodiment includes conversion means 2A and purification means 3 .
The conversion means 2A contacts the raw material gas with a catalyst layer 111 containing a catalyst, converts ethanol and acetaldehyde in the raw material gas into 1,3-butadiene, and obtains a crude product gas containing 1,3-butadiene. A reactor 110 is provided.
Purification means 3 includes a distillation column (described later) for purifying the crude product gas obtained in conversion means 2A.
100 A of manufacturing apparatuses are equipped with the connection piping 40 which connects the reactor 110 and the refinement|purification means 3. As shown in FIG.

Two reactors 110 are installed in parallel. A pipe 29 is connected to the reactor 110 , and a valve 32 is provided at each branch portion of the pipe 29 on the side of the reactor 110 . An analyzer 35 is provided in the pipe 29 . A pipe 37 is connected to the upstream side of the analyzer 35 of the pipe 29 . A flow indicator adjuster 27 is provided in the pipe 37 . Based on the analysis result of the analyzer 35, the flow rate of the pipe 37 can be adjusted.

A valve 42 is provided at each branch portion of the connecting pipe 40 on the side of the reactor 110 . The connecting pipe 40 is provided with three bent portions R1, R2, and R3. Although there are three bent portions in this embodiment, the number of bent portions is not particularly limited. For example, the number of bends may be 0-20 or 1-10. A bypass 41 is provided in parallel with the connection pipe 40 , and a valve 45 is provided at each branch of the bypass 41 . A valve 43 is provided in a portion of the connecting pipe 40 parallel to the bypass 41 . The portion sandwiched between the valves 45 of the bypass 41 is removable. The portion sandwiched by the valve 43 of the connecting pipe 40 is detachable.

As the reactor 110, any reactor can be used as long as the source gas can be brought into contact with the catalyst layer containing the catalyst at a predetermined pressure and temperature. For example, a catalyst layer (reaction bed) is formed by filling a catalyst in a reaction tube in which a heat medium is circulated in the side wall portion, and the supplied raw material gas is subjected to contact treatment with the catalyst in the catalyst layer. The reaction bed is not particularly limited, and examples thereof include fixed bed, moving bed and fluidized bed.

The number of reactors 110 installed in parallel can be set appropriately, and is preferably 2 to 10, more preferably 2 to 8, and even more preferably 4 to 8, for example. When the number of reactors 110 installed in parallel is equal to or greater than the above lower limit, maintenance of the remaining reactors can be performed while the conversion reaction is being performed in one reactor. When the number of reactors 110 installed in parallel is equal to or less than the above upper limit, the control of the manufacturing apparatus 100A can be facilitated.

The manufacturing apparatus 100A has one heating means (not shown) for heating the reactor 110 . Examples of heating means include heaters, heat exchangers, furnaces, electric heaters, and microwave irradiators.
The manufacturing apparatus 100A preferably has two or more heating means for heating the reactor 110 . Since the manufacturing apparatus 100A has two or more heating means, the inlet side (of the raw material gas) of the catalyst layer 111 can be further heated. Therefore, it is possible to suppress the temperature decrease due to the conversion reaction, and suppress the decrease in the catalytic activity of the catalyst contained in the catalyst layer 111 . As a result, the yield of 1,3-butadiene can be increased.
The reason why the inlet side of the catalyst layer 111 is further heated is that the conversion reaction occurs actively at the inlet side of the catalyst layer 111, and the central portion of the catalyst layer 111 and the outlet side (of the crude gas) of the catalyst layer 111 are heated. This is because the temperature drop on the inlet side of the catalyst layer 111 is larger than that.

When the inlet side of the catalyst layer 111 is further heated, the heating temperature is preferably 5 to 100° C. higher, more preferably 10 to 90° C. higher than the central portion and the outlet side temperature of the catalyst layer 111. 80° C. higher is even more preferred. When the heating temperature is equal to or higher than the above lower limit, temperature drop due to the conversion reaction can be suppressed. When the heating temperature is equal to or lower than the above upper limit, temperature drop due to overheating can be suppressed.

As shown in FIG. 2, let L be the length of the catalyst layer 111 in the reactor 110 in the flow direction of the raw material gas. At this time, the region from the entrance side of the raw material gas in the catalyst layer 111 to L/3 is defined as a first area F1. A region from the first area F1 to L/3 is defined as a second area F2. A region from the second area F2 to L/3 is defined as a third area F3.
Let k1 be the catalytic activity of the catalyst filled in the first area F1, and w1 be the total mass of the catalyst.
Let k2 be the catalytic activity of the catalyst filled in the second area F2, and w2 be the total mass of the catalyst.
Let k3 be the catalytic activity of the catalyst filled in the third area F3, and w3 be the total mass of the catalyst.
At this time, the manufacturing apparatus 100A preferably satisfies the following formula (a).
k1×w1<k2×w2<k3×w3 (a)

In the reactor 110, the conversion reaction to 1,3-butadiene actively occurs on the inlet side of the catalyst layer 111, and the conversion reaction becomes less likely to occur from the central portion of the catalyst layer 111 toward the outlet side of the catalyst layer 111. . Therefore, if the catalytic activity is uniform throughout the catalyst layer 111, the temperature on the inlet side of the catalyst layer 111 will drop sharply, and the yield of 1,3-butadiene will decrease.
Therefore, the manufacturing apparatus 100A controls the catalytic activity and the mass of the catalyst filled in the catalyst layer 111 so as to satisfy the formula (a). The conversion reaction can always be maintained in a nearly homogeneous state. As a result, the yield of 1,3-butadiene can be increased.
Methods for controlling the catalytic activity and the mass of the catalyst packed in the catalyst layer 111 so as to satisfy the formula (a) include, for example, (i) a method using catalysts having different catalytic activities; A method of adjusting the mass of the catalyst by addition, (iii) a method of applying a reactor having a shape in which the mass of the catalyst can be increased toward the exit side of the catalyst layer, and the like.

When the reactor 110 shown in FIG. 2 is applied, as the method (i), for example, a catalyst having a catalytic activity of k1 is placed in the first area F1, and a catalyst having a catalytic activity of k2 is placed in the second area F2. , a method of filling an equal amount of a catalyst having a catalytic activity of k3 in the third area F3 and selecting a catalyst that satisfies k1<k2<k3. According to this method, since w1=w2=w3, the expression (a) is satisfied.
As the method (ii) above, for example, one type of catalyst having a catalytic activity of k1 is applied, and the amount of diluent added to the first area F1 and the second area F2 is higher in the first area F1. A method of adding each diluent so as to increase the amount can be mentioned. According to this method, since w1<w2<w3, the expression (a) is satisfied.
As the shape of the reactor 110, there is a shape in which the cross-sectional shape of the reactor is constant with respect to the flow direction of the raw material gas. Examples of such shapes include cylinders, elliptical cylinders, triangular prisms, square prisms, pentagonal prisms, hexagonal prisms, and the like. Generally, cylindrical reactors are used.

As the method (iii), for example, a method of applying a reactor 110b having a larger cross-sectional shape with respect to the flow direction of the raw material gas as shown in FIG. 3 can be mentioned.
When applying the reactor 110b shown in FIG. 3, for example, a method of filling each of the first area G1, the second area G2, and the third area G3 with one type of catalyst having a catalytic activity of k1 can be used. According to this method, since w1<w2<w3, the expression (a) is satisfied.
Examples of the shape of the reactor 110b include cones, elliptical pyramids, triangular pyramids, square pyramids, pentagonal pyramids, and hexagonal pyramids. As for the shape of the reactor 110b, a conical shape is preferable because the contact area with the catalyst layer 111b can be increased.

The catalytic activities k1, k2 and k3 described above can be measured by the following method by taking out the catalyst filled in each area.
Using the removed catalyst, ethanol is converted to 1,3-butadiene (hereinafter also referred to as "BD"), and the yield of 1,3-butadiene is determined. These yield values are defined as activity values (catalytic activities k1, k2, k3).
Specifically, 0.5 g of the catalyst is first packed into a 1/2 inch (1.27 cm) diameter, 15.7 inch (40 cm) long stainless steel cylindrical reaction tube to form a reaction bed. .
Next, the reaction temperature (temperature of the reaction bed) is set to 325° C. and the reaction pressure (pressure of the reaction bed) is set to 0.1 MPa.
In this state, the raw material is supplied to the reaction tube at a space velocity (SV) of 1200 h ⁻¹ to obtain a product gas containing 1,3-butadiene.
A mixed gas of 30% by volume of ethanol (converted to gas) and 70% by volume of nitrogen (converted to gas) is used as the raw material.
After 1 hour from the start of supplying the raw material, the generated gas is recovered.
Then, each of the collected generated gases is analyzed by gas chromatography to obtain the selectivity of BD, the conversion of raw material, and the yield of BD ([conversion of raw material]×[selectivity of BD]).
The "selectivity of BD" is the percentage of the number of moles of the raw material converted to BD to the number of moles of the raw material consumed in the reaction using the catalyst.
Further, the "conversion rate of the raw material" is the percentage of the number of moles consumed of the raw material contained in the raw material gas.

When the catalyst layer has two areas, the formula (a) can be read as the following formula (b).
k1×w1<k2×w2 (b)

When the number of areas of the catalyst layer is four or more, the (n-1)-th area and the n-th area shall satisfy the following formula (c). However, n represents a natural number of 2 or more.
k(n−1)×w(n−1)<kn×wn (c)
Here, the n-th area is an area sequentially divided from the inlet side of the raw material gas of the catalyst layer in the reactor to the outlet side. That is, the area closest to the entrance side is the first area, and the area furthest from the entrance side (the area closest to the exit side) is the n-th area.

As the connection pipe 40, a stainless steel pipe or the like having corrosion resistance and heat resistance can be used. As the bypass 41, a steel pipe or the like similar to the connecting pipe 40 can be used.

The crude product gas discharged from the reactor 110 flows through the connecting pipe 40 . Therefore, by-products generated by the conversion reaction may adhere to the inner surface (flow path) of the connecting pipe 40 . Adhesion of by-products to the inner surface of the connecting pipe 40 may cause clogging of the connecting pipe 40 and pressure loss. Therefore, it is preferable that the connection pipe 40 has the following configuration.

In the connection pipe 40, the radius of curvature at the bent portion Rm is preferably 20 mm or more, more preferably 25 mm or more, and even more preferably 30 mm or more. When the radius of curvature of the bent portion Rm is equal to or greater than the above lower limit, it is possible to prevent accumulation of by-products, particularly brown oil. The upper limit of the radius of curvature of the bent portion Rm is not particularly limited, and is set to 100 mm, for example.
The radius of curvature of each bent portion Rm is given by the radius of a circle when the curve of the inner surface of each bent portion Rm is regarded as an arc. Here, m represents a natural number. For example, m is preferably from 1 to 20, more preferably from 1 to 10, and even more preferably from 1 to 5. In this embodiment, m is 1-3. Note that m increases as the distance from the second reactor 110 increases, as shown in FIG. For example, if there are three bends as shown in FIG. 1, the bend closest to the second reactor 110 is R1 and the furthest bend is R3.
When two straight pipes are connected by a joint or the like to form a bent portion, the curvature radius of the joint or the like is regarded as the curvature radius of the connecting pipe 40 at the bent portion.

The value (r _Rm /T _Rm ) obtained by dividing the radius of curvature (r _Rm (mm)) of the bent portion Rm by the temperature T _Rm (K) of the inner surface of the bent portion Rm is preferably 0.03 to 100 mm/K, and 0 0.05 to 80 mm/K is more preferred, and 0.07 to 60 mm/K is even more preferred. When r _Rm /T _Rm is equal to or higher than the above lower limit, the temperature T _Rm is high, and the brown oil has a high fluidity, so that the brown oil is less likely to accumulate on the inner surface of the bent portion Rm. When r _Rm /T _Rm is equal to or less than the above upper limit value, the radius of curvature (r _Rm ) is large, so brown oil is less likely to accumulate on the inner surface of the bent portion Rm.

The value (r _Rm /r' Rm ) obtained by dividing the radius of curvature (r _Rm (mm)) of the bend Rm by the radius (r' _Rm (mm)) of the pipe at the bend _Rm is 0.02 to 1.00. is preferred, 0.03 to 0.80 is more preferred, and 0.05 to 0.60 is even more preferred. When r _Rm /r′ _Rm is equal to or greater than the above lower limit, the radius (r′ _Rm (mm)) of the pipe at the bent portion Rm is small, and the dispersibility of the brown oil increases. hard to accumulate. When r _Rm /r′ _Rm is equal to or less than the above upper limit value, the radius of curvature (r _Rm (mm)) of the bent portion Rm is large, so brown oil is less likely to accumulate on the inner surface of the bent portion Rm. The radius (r' _Rm (mm)) of the pipe at the bent portion Rm means the length obtained by dividing the inner diameter of the pipe at the bent portion Rm by 2.

The value (r _Rm /μ _Rm ) obtained by dividing the radius of curvature (r _Rm (mm)) of the bent portion Rm by the viscosity (μ _Rm (mPa·s)) of the by-product adhering to the inner surface of the bent portion Rm is 0. 04 mm/mPa·s or more is preferable, 0.05 mm/mPa·s or more is more preferable, and 0.06 mm/mPa·s or more is even more preferable. When r _Rm /μ _Rm is equal to or greater than the above lower limit value, the radius of curvature (r _Rm (mm)) of the bent portion Rm is large, so brown oil is less likely to accumulate on the inner surface of the bent portion Rm. Although the upper limit of r _Rm /μ _Rm is not particularly limited, it is, for example, 1.0 mm/mPa·s. The viscosity (μ _Rm (mPa s)) of the by-product adhering to the inner surface of the bent portion Rm was measured by sampling 10 mL of the by-product adhered to the inner surface of the bent portion Rm and using a Brookfield viscometer. The value shall be measured at 190°C.

The arithmetic average roughness (Ra ₄₀ (μm)) of the inner surface of the connection pipe 40 is preferably 1.02 μm or less, more preferably 1.00 μm or less, still more preferably 0.90 μm or less, and particularly preferably 0.80 μm or less. When the arithmetic mean roughness of the inner surface of the connecting pipe 40 is equal to or less than the above upper limit value, adhesion of by-products, particularly brown oil, can be suppressed. The lower limit of the arithmetic mean roughness of the inner surface of the connecting pipe 40 is not particularly limited, but is set to 0.01 μm, for example.
The arithmetic mean roughness of the inner surface of the connection pipe 40 is measured using a roughness curve described in JIS B0601:2013 with a cutoff value of 2.5 using Handysurf E-35B manufactured by Tokyo Seimitsu Co., Ltd. Arithmetic mean roughness.
The arithmetic average roughness of the inner surface of the connection pipe 40 can be adjusted by the material of the connection pipe 40, maintenance of the connection pipe 40, and the like.

When the temperature of the inner surface of the connecting pipe 40 is T ₄₀ (K), the product of the arithmetic mean roughness (Ra ₄₀ (μm)) of the connecting pipe 40 and T ₄₀ ( Ra ₄₀ ·T ₄₀ ) is preferably from 0.1 to 750 µm·K, more preferably from 0.5 to 550 µm·K, even more preferably from 1.0 to 480 µm·K. When Ra ₄₀ ·T ₄₀ is equal to or higher than the above lower limit, the temperature T ₄₀ is high and the fluidity of the brown oil is increased. When Ra ₄₀ ·T ₄₀ is equal to or less than the above upper limit value, brown oil is less likely to accumulate on the inner surface of the connecting pipe 40 because Ra ₄₀ is small.
Note that T ₄₀ (K) is the temperature of the inner surface of the connecting pipe 40 at the position having the arithmetic mean roughness.

When the pipe radius of the connecting pipe 40 is r ₄₀ (mm), the product of the arithmetic mean roughness (Ra ₄₀ (μm)) of the connecting pipe 40 and r ₄₀ (Ra ₄₀ ·r ₄₀ ) is 0.002 to 1 mm ² is preferred, 0.005-0.8 mm ² is more preferred, and 0.01-0.5 mm ² is even more preferred. If Ra ₄₀ ·r ₄₀ is equal to or greater than the above lower limit, brown oil is less likely to accumulate on the inner surface of the connecting pipe 40 because Ra ₄₀ is small. When Ra ₄₀ ·r ₄₀ is equal to or less than the above upper limit, the pipe radius r ₄₀ is wide, and brown oil is less likely to accumulate on the inner surface of the connection pipe 40 because the dispersibility of brown oil increases.
Note that r ₄₀ (mm) is the radius of the connecting pipe 40 (1/2 of the inner diameter of the pipe) at the position having the arithmetic mean roughness.

A value obtained by dividing the arithmetic average roughness (Ra ₄₀ (μm)) of the connecting pipe 40 by μ 40 _{(Ra 40 /} μ ₄₀ ), where μ ₄₀ (mPa·s) is the viscosity of the by-product in the connecting pipe 40 is preferably 0.0001 µm/mPa·s or more, more preferably 0.0002 µm/mPa·s or more, and still more preferably 0.0005 µm/mPa·s or more. When Ra ₄₀ /μ ₄₀ is equal to or higher than the above lower limit, brown oil is less likely to accumulate on the inner surface of the connecting pipe 40 because Ra ₄₀ is small. Although the upper limit of Ra ₄₀ /μ ₄₀ is not particularly limited, it is, for example, 0.01 μm/mPa·s.
Here, μ ₄₀ (mPa·s) is the viscosity at 190° C. of the by-product at the location of the arithmetic mean roughness in the connection pipe 40 .

The inner surface of the connecting pipe 40 is preferably coated with an organic compound having 6 to 12 carbon atoms. Since the inner surface of the connecting pipe 40 is coated with an organic compound having 6 to 12 carbon atoms, it is possible to suppress adhesion of brown oil to the inner surface of the connecting pipe 40 .
Examples of organic compounds having 6 to 12 carbon atoms include hydrocarbons having 7 to 10 carbon atoms, alcohols, aldehydes, ketones, ethers, esters, carboxylic acids, phenols and the like. More specific examples include δ-hexanolactone, 2,6-diisopropylphenol, 1-adamantylmethylketone and the like.

As used herein, the term “coated” means that a coating layer having a thickness of 100 mm or less is formed on the inner surface of the connecting pipe 40 . The thickness of the coating layer is preferably 0.001-100 mm, more preferably 0.01-10 mm. If the thickness of the coating layer is equal to or greater than the lower limit value, adhesion of brown oil to the inner surface of the connecting pipe 40 can be suppressed. When the thickness of the coating layer is equal to or less than the above upper limit, clogging of piping and pressure loss can be suppressed. The thickness of the coating layer can be measured by observing, with a microscope or the like, a cross section obtained by cutting the bent portion of the connecting pipe 40 closest to the reactor 110 in the thickness direction of the connecting pipe 40 . In this case, the thickness of the coating layer is measured at 10 randomly selected points from the flow channel at the bend closest to the reactor 110 of the connection pipe 40, and the arithmetic mean value of the measured values is the "thickness of the coating layer. ”.
In addition, “the bent portion of the connecting pipe 40 closest to the reactor 110 ” refers to the portion of the connecting pipe 40 that has a radius of curvature of 100 mm or less and is closest to the reactor 110 . In this embodiment, the bent portion R1 is the bent portion of the connecting pipe 40 that is closest to the reactor 110 .

The temperature of the inner surface of the connecting pipe 40 at the bend closest to the reactor 110 (T _R1 (K)) is relative to the temperature of the inner surface of the reactor 110 (T ₁₁₀ (K), the temperature of the central portion of the catalyst layer 111). The temperature is preferably −250° C. or higher, more preferably −200° C. or higher, and still more preferably −150° C. or higher. When the temperature of the inner surface of the connecting pipe 40 at the bent portion closest to the reactor 110 is equal to or higher than the above lower limit, it is possible to suppress adhesion of brown oil to the inner surface of the connecting pipe 40 . The upper limit of the temperature of the inner surface of the connecting pipe 40 at the bend closest to the reactor 110 is not particularly limited, but is set to ±0° C. with respect to the temperature of the inner surface of the reactor 110, for example.

The temperature drop of the inner surface of the connecting pipe 40 at the bend closest to the reactor 110 (hereinafter also simply referred to as “temperature drop”) is 70% relative to the temperature of the inner surface of the reactor 110 (T ₁₁₀ (K)). % or less is preferable, 60% or less is more preferable, and 50% or less is even more preferable. If the temperature drop is equal to or less than the upper limit value, adhesion of brown oil to the inner surface of the connecting pipe 40 can be suppressed. The lower limit of the temperature drop is not particularly limited, but is set to 0%, for example.
Note that the temperature drop is obtained by the following formula (d).
Temperature drop (%) = (T ₁₁₀ (K) - T _R1 (K))/T ₁₁₀ (K) x 100 (d)

The pipe radius (r′ _R1 (mm)) of the connecting pipe 40 at the bend closest to the reactor 110 is preferably 50 to 1000 mm, more preferably 80 to 800 mm, and even more preferably 100 to 500 mm. If the pipe radius (r′ _R1 (mm)) is equal to or greater than the above lower limit value, adhesion of brown oil to the inner surface of the connecting pipe 40 can be suppressed. When the pipe radius (r' _R1 (mm)) is equal to or less than the above upper limit, maintenance of the connection pipe 40 is facilitated. The radius of the pipe (r' _R1 (mm)) is the radius of the pipe at the bent portion R1 (1/2 of the inner diameter of the pipe).

The reduction rate of the pipe radius at the bend closest to the reactor 110 of the connection pipe 40 is, with respect to the pipe radius before the bend (r' _front (mm), 1/2 of the inner diameter of the pipe before the bend), 70% or less is preferable, 60% or less is more preferable, and 50% or less is even more preferable. If the reduction rate of the pipe radius is equal to or less than the upper limit value, adhesion of brown oil to the inner surface of the connection pipe 40 can be suppressed. The lower limit of the pipe radius reduction rate is not particularly limited, but is set to 0%, for example. The reduction rate of the pipe radius is obtained by the following formula (e).
Reduction rate of pipe radius (%) = (r' _front (mm) - r' _rear (mm)) / r' _front (mm) x 100 (e)
In equation (e), _after r' (mm) is the radius of the pipe after bending (1/2 of the inner diameter of the pipe after the bend).

A main component of the by-product that may adhere to the inner surface of the bent portion of the connecting pipe 40 closest to the reactor 110 is a compound having 4 or more carbon atoms produced by polymerization of acetaldehyde. Examples of these compounds include δ-hexanolactone, 2,6-diisopropylphenol, 1-adamantylmethylketone and the like. These compounds can be detected by gas chromatography (GC) analysis of the by-products trapped in the bypass 41 of the manufacturing apparatus 100A.
The viscosity (μ _R1 (mPa·s)) of by-products that can adhere to the inner surface of the bent portion of connecting pipe 40 closest to reactor 110 varies depending on the mixing ratio of these compounds. The viscosity (μ _R1 (mPa·s)) of the by-product is preferably 100 to 800 mPa·s. The viscosity of the by-product (μ _R1 (mPa s)) is the viscosity measured at 20° C. using a coaxial double cylindrical rotational viscometer (constant inner cylinder speed method) described in JIS Z8803:2011. is.

A bypass 41 is provided in parallel with the connection pipe 40 . By opening the valve 45 , the crude product gas can be passed through the bypass 41 . By making the arithmetic mean roughness (Ra ₄₁ ) of the inner surface of the bypass 41 larger than Ra ₄₀ and making the temperature T ₄₁ of the inner surface of the bypass 41 lower than T ₄₀ , by-products, In particular, brown oil can be easily collected. That is, the bypass 41 can be used as a by-product trap. By providing the bypass 41 with a bent portion with a small radius of curvature or installing a filter with an appropriate grid size, the function as a trap can be further enhanced.

The bypass 41 has a detachable portion sandwiched between the valves 45 . By making the bypass 41 removable, maintenance can be performed without stopping the continuous operation of the manufacturing apparatus 100A by replacing it with a new bypass or cleaning the inner surface when the by-product adheres to the inner surface. can do. When the bypass 41 is to be maintained, the valve 45 is closed and the bypass 41 is removed. In addition to the trap by the bypass pipe, install a detachable filter with an appropriate grid size on the connecting pipe and/or the bypass pipe, and maintain the manufacturing equipment by appropriately removing the adhered and accumulated by-products. can also

When the connecting pipe 40 becomes dirty, the valve 43 is closed and the valve 45 is opened to allow the crude gas to flow through the bypass 41 . Since the portion sandwiched by the valve 43 of the connecting pipe 40 is detachable, it is possible to perform maintenance on this portion.

A bypass other than the bypass 41 may be provided in the connection pipe 40 . By providing a bypass other than the bypass 41, more by-products can be recovered.
The number of bypasses may be one, or two or more.

The manufacturing apparatus 100A preferably further includes a diluting device. By providing the dilution device, the inert gas content in the source gas supplied to the reactor can be easily controlled.
The diluting device is provided in the preceding stage of the reactor 110 and dilutes a gas containing ethanol and acetaldehyde (an “intermediate gas” described later) with an inert gas.
In the present embodiment, the flow indicator adjuster 27, the analyzer 35, and the pipe 37 constitute a dilution device.
The analyzer 35 analyzes the ethanol concentration in the gas containing ethanol and acetaldehyde. Based on the result, the flow rate indicator adjuster 27 adjusts the flow rate of the inert gas from the pipe 37 to control the inert gas concentration in the raw material gas supplied to the reactor 110 to 5 to 50% by volume. Since the inert gas concentration in the raw material gas is controlled to 5 to 50% by volume, adhesion of by-products to piping can be suppressed without lowering the yield of 1,3-butadiene.

As described above, in the manufacturing apparatus 100A, the connecting pipe 40 has the characteristics described above. For this reason, it is possible to prevent brown oil from adhering to the inner surface of the connecting pipe 40, and to easily remove the generated by-product.
In addition, in the manufacturing apparatus 100A, the catalyst layer 111 of the reactor 110 has the characteristics described above. Therefore, the conversion reaction can be promoted in a nearly uniform state. As a result, the yield of 1,3-butadiene can be increased.

Next, a method for producing 1,3-butadiene using the 1,3-butadiene production apparatus 100 shown in FIG. 4 will be described.
In the present embodiment, in the method for producing 1,3-butadiene using the production apparatus 100A described above, the first reactor 108 described later is provided upstream of the reactor 110, and the gas-liquid gas described later is provided downstream of the reactor 110. This is a method for producing 1,3-butadiene when a separator 112 is provided.
In this embodiment, the second reactor 110, which will be described later, is the same as the reactor 110 in the manufacturing apparatus 100A.
In this embodiment, step B3, which will be described later, is the same as the conversion step described above.
In this embodiment, the second catalyst, which will be described later, is the same as the catalyst contained in the catalyst layer 111 in the manufacturing apparatus 100A.

The method for producing 1,3-butadiene of the present embodiment is a method for continuously producing 1,3-butadiene from an ethanol feedstock containing ethanol.
The method for producing 1,3-butadiene of the present embodiment includes steps A, B, and C below. Further, the method for producing 1,3-butadiene of the present embodiment preferably further includes step D from the viewpoint of improving the yield of 1,3-butadiene.
In the method for producing 1,3-butadiene of the present embodiment, the hydrogen concentration in the following intermediate gas or the following mixed gas is controlled to less than 15% by volume.
In the method for producing 1,3-butadiene of the present embodiment, the content of the inert gas in the following intermediate gas or the following mixed gas is 5 to 50% by volume.

Step A: Gas preparation step to prepare an ethanol-containing gas from an ethanol feedstock.
Step B: A conversion step of converting ethanol in the ethanol-containing gas to 1,3-butadiene in the presence of a catalyst to obtain a 1,3-butadiene-containing gas.
Step C: Purification step of purifying the 1,3-butadiene-containing gas to obtain purified 1,3-butadiene.
Step D: A catalyst regeneration step for regenerating the catalyst.

(Process A)
Step A includes step A1 of vaporizing an ethanol feedstock under conditions of -1.0 to 3.0 MPaG in pressure and -100 to 400°C in temperature to form an ethanol-containing gas.

The ethanol feedstock essentially contains ethanol, and may contain other components such as water as long as the effects of the present invention are not impaired. The ratio of ethanol in the ethanol feedstock is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 93% by mass or more, relative to the total mass of the ethanol feedstock. The upper limit of the proportion of ethanol is theoretically 100% by weight.
The ethanol contained in the ethanol feedstock is the same as the ethanol contained in the feed gas described above.

The pressure during vaporization of the ethanol feedstock in step A1 may be set in the range of -1.0 to 3.0 MPaG, preferably -0.5 to 2.0 MPaG, more preferably -0.3 to 1.0 MPaG. preferable. If the pressure at the time of vaporization is equal to or higher than the lower limit of the above range, the volume at the time of vaporization does not become excessive and the size of machinery and equipment can be suppressed. If the pressure at the time of vaporization is equal to or lower than the upper limit value of the above range, vaporization will be efficient.

The temperature during vaporization of the ethanol feedstock in step A1 may be set in the range of -100 to 400°C, preferably 0 to 200°C, more preferably 25 to 100°C. If the temperature at the time of vaporization is equal to or higher than the lower limit of the above range, vaporization will be efficient. Excessive heating is unnecessary if the temperature at the time of vaporization is equal to or lower than the upper limit of the above range.

In step A, if necessary, the ethanol-containing gas obtained in step A1 is mixed with one or more gases, and the concentration of ethanol in the ethanol-containing gas is adjusted within the range of 0.1 to 100% by volume. A2 may be further included.

The ethanol concentration of the ethanol-containing gas may be adjusted in the range of 0.1 to 100% by volume, preferably 10 to 100% by volume, more preferably 20 to 100% by volume. If the ethanol concentration is at least the lower limit of the above range, the yield of 1,3-butadiene is improved.

As the gas (diluent gas) to be mixed with the ethanol-containing gas, a gas that does not adversely affect the conversion reaction from ethanol to 1,3-butadiene can be used. For example, noble gases such as nitrogen gas and argon gas, and carbon dioxide can be exemplified. Among them, nitrogen gas and argon gas are preferable in terms of price and availability. The gas to be mixed with the ethanol-containing gas may be used singly or in combination of two or more.

(Step B)
Step B includes at least one step selected from the group consisting of steps B1 to B4 below.
Step B1: A first conversion step of contacting the ethanol-containing gas with a first catalyst to convert part of the ethanol in the ethanol-containing gas into acetaldehyde to obtain an intermediate gas containing ethanol and acetaldehyde.
Step B2: A step of mixing the intermediate gas and a gas containing ethanol to obtain a mixed gas.
Step B3: contacting the intermediate gas or a mixed gas obtained by mixing the intermediate gas and a gas containing ethanol with a second catalyst to remove ethanol and acetaldehyde from the intermediate gas or the mixed gas, A second conversion step of converting to 1,3-butadiene to obtain a 1,3-butadiene-containing gas.
Step B4: A hydrogen concentration reducing step of reducing the hydrogen concentration in the intermediate gas or the mixed gas.

In step B1, the ethanol-containing gas obtained in step A is subjected to contact treatment with a first catalyst filled in a first reactor described later to convert part of the ethanol in the ethanol-containing gas into acetaldehyde, ethanol and An intermediate gas containing acetaldehyde is obtained. The reaction of step B1 is represented by the following formula (2).
CH ₃ CH ₂ OH→CH ₃ CHO+H ₂ (2)

Any mode of the first reactor may be used as long as the ethanol-containing gas can be brought into contact with the first catalyst at a predetermined pressure and temperature. For example, a reaction bed is formed by filling the first catalyst in a reaction tube in which a heat medium is circulated in the side wall portion, and the supplied ethanol-containing gas is contacted with the first catalyst of the reaction bed for treatment. The reaction bed is not particularly limited, and examples thereof include fixed bed, moving bed and fluidized bed.

Two or more parallel reactors may be used in step B1. The number of reactors to be installed in parallel in step B1 can be set appropriately, and can be, for example, 2 to 5.

Any catalyst can be used as the first catalyst as long as it promotes the conversion reaction of ethanol to acetaldehyde, and examples thereof include a mixture of chromium oxide and copper oxide, zinc oxide, and a mixture of copper oxide and silicon oxide. Among them, a mixture of copper oxide and silicon oxide is preferable from the viewpoint of conversion rate of ethanol. A 1st catalyst may be used individually by 1 type, and may use 2 or more types together.

The pressure of all gases in the first reactor during the conversion reaction in step B1 may be set in the range of 0 to 1.0 MPaG, preferably 0 to 0.5 MPaG, more preferably 0 to 0.3 MPaG. If the pressure in step B1 is equal to or higher than the lower limit of the range, the conversion of ethanol is improved. If the pressure in step B1 is equal to or lower than the upper limit of the range, liquefaction during the reaction can be suppressed.

The temperature during the conversion reaction in step B1 may be set in the range of 50 to 500°C, preferably 200 to 500°C, more preferably 250 to 350°C. When the temperature in step B1 is equal to or higher than the lower limit of the above range, the conversion of ethanol is improved. When the temperature in step B1 is equal to or lower than the upper limit of the range, excessive energy consumption can be suppressed.

The gas hourly space velocity (GHSV) of the ethanol-containing gas with respect to the first catalyst is preferably 1000 to 20000 h ^-1 , more preferably 2000 to 15000 h ^-1 , more preferably 3000 to 10000 h ^-1 in terms of standard conditions. preferable. When the GHSV is equal to or higher than the lower limit, the ethanol-containing gas processing capacity is increased. When the GHSV is equal to or less than the upper limit, the ethanol conversion rate is improved.
The GHSV of the ethanol-containing gas relative to the first catalyst is obtained by dividing the flow rate of the ethanol-containing gas in terms of standard conditions by the filling amount of the first catalyst (the volume of the catalyst layer).

The GHSV of ethanol in the ethanol-containing gas with respect to the first catalyst is preferably 500 to 20,000 h ^-1 , more preferably 1,000 to 15,000 h ^-1 , and even more preferably 1,500 to 10,000 h ^-1 in terms of standard conditions. When the GHSV is equal to or higher than the lower limit, the ethanol-containing gas processing capacity is increased. When the GHSV is equal to or less than the upper limit, the ethanol conversion rate is improved.
The GHSV of ethanol in the ethanol-containing gas relative to the first catalyst is obtained by dividing the flow rate of ethanol in terms of standard conditions by the filling amount of the first catalyst (the volume of the catalyst layer).

The conversion of ethanol in step B1 is preferably 30-100%, more preferably 40-90%.
The "conversion rate of ethanol" in step B1 is the number of moles per unit time of ethanol in the ethanol-containing gas supplied to the reactor in step B1, and the ethanol consumed in the reactor per unit time. means the ratio (percentage) of the number of moles of The number of moles per unit time of ethanol consumed in the reactor of step B1 is calculated from the number of moles per unit time of ethanol in the ethanol-containing gas supplied to the reactor of step B1 from the reactor of step B1. It is calculated by subtracting the number of moles per unit time of ethanol in the discharged intermediate gas.

The acetaldehyde selectivity of the conversion reaction in step B1 is preferably 80 to 100%, more preferably 90 to 100%. The “acetaldehyde selectivity” in step B1 refers to the ratio of the number of moles of ethanol converted to acetaldehyde per unit time to the number of moles per unit time of ethanol consumed in the reactor of step B1 ( percentage).
By-products that can be contained in the intermediate gas obtained in step B1 include crotonaldehyde, butyraldehyde, ethyl acetate, acetic acid, and the like.

The yield of acetaldehyde in the conversion reaction of step B1 is preferably 25-100%, more preferably 35-90%. The "yield of acetaldehyde" in step B1 means "conversion rate of ethanol" x "selectivity of acetaldehyde". When the yield of acetaldehyde is equal to or less than the upper limit, the amount of hydrogen produced decreases, the concentration of hydrogen in the intermediate gas or mixed gas described later decreases, and as a result the yield of 1,3-butadiene increases. .

The molar ratio (ethanol/acetaldehyde) in the mixed gas is preferably 1-100, more preferably 1-50, even more preferably 1-20, even more preferably 1-10, and particularly preferably 1-5. When the molar ratio is within the above range, the yield of 1,3-butadiene is improved.

In step B2, based on the results of monitoring the molar ratio (ethanol/acetaldehyde) in the intermediate gas obtained in the first conversion step with an analyzer, the shortage of ethanol is increased so as to achieve the optimum reaction ratio. A gas containing ethanol is mixed with the intermediate gas. The ethanol-containing gas includes a portion of the ethanol-containing gas obtained in step A and a portion of the ethanol-containing gas supplied from another source. This makes it easier to control the molar ratio (ethanol/acetaldehyde) within the above range.
The analyzer is installed between the point where step B2 is performed and the inlet of the second reactor in step B3 described later, and analyzes the molar ratio (ethanol / aldehyde) supplied to the second reactor over time. . As a result, any change in gas flow rate, such as change in each gas flow rate over the entire butadiene production process, change in each gas flow rate due to deterioration of the catalyst and/or equipment over time, etc., can be constantly observed.
Examples of analyzers include process mass spectrometers and gas analyzers.

In step B3, the intermediate gas obtained in step B1 or the mixed gas obtained in step B2 is brought into contact with a catalyst layer containing a second catalyst filled in a second reactor described later, to obtain the intermediate gas or Ethanol and acetaldehyde in the mixed gas are converted to 1,3-butadiene to obtain a 1,3-butadiene-containing gas. The reaction of step B3 is represented by the following formula (1) described above.
CH ₃ CH ₂ OH+CH ₃ CHO→CH ₂ =CH-CH=CH ₂ +2H ₂ O (1)

As an aspect of the second reactor in step B3, the same aspect as the reactor 110 shown in FIG. 1 can be exemplified. In step B3, as in step B1, two or more parallel reactors may be used. The number of reactors to be installed in parallel in step B3 can be set appropriately, and can be, for example, 2 to 5.

As the second catalyst, the same catalyst as the “catalyst” applied to the catalyst layer 111 shown in FIG. 1 can be exemplified.

The pressure of all gases in the second reactor during the conversion reaction in step B3 may be set in the range of 0 to 1.0 MPaG, preferably 0 to 0.5 MPaG, more preferably 0 to 0.3 MPaG. If the pressure in step B3 is at least the lower limit of the above range, the yield of 1,3-butadiene is improved. If the pressure in step B3 is equal to or lower than the upper limit of the above range, it is possible to suppress the decrease in yield of 1,3-butadiene due to excessive reaction.

The temperature during the conversion reaction in step B3 may be set in the range of 50 to 500°C, preferably 300 to 400°C, more preferably 320 to 370°C. If the temperature in step B3 is at least the lower limit of the above range, the yield of 1,3-butadiene is improved. If the temperature in step B3 is equal to or lower than the upper limit of the above range, it is possible to suppress the decrease in the yield of 1,3-butadiene due to overreaction.

The GHSV of the intermediate gas or the mixed gas with respect to the second catalyst is preferably 100 to 10000 h ^-1 , more preferably 200 to 8000 h ^-1 and even more preferably 400 to 6000 h ^-1 in terms of standard conditions. When the GHSV is equal to or higher than the lower limit, the ethanol-containing gas processing capacity is increased. When the GHSV is equal to or less than the upper limit, the conversion rate of ethanol and acetaldehyde is improved.
The GHSV of the intermediate gas or mixed gas is obtained by dividing the flow rate of the intermediate gas or mixed gas in terms of standard conditions by the filling amount of the second catalyst (the volume of the catalyst layer).

The total GHSV of ethanol and acetaldehyde in the intermediate gas or the mixed gas for the second catalyst is preferably 100 to 3000 h ^-1 , more preferably 200 to 2500 h ^-1 , and 400 to 2000 h ^-1 in terms of standard conditions. More preferred. When the GHSV is equal to or higher than the lower limit, the ethanol-containing gas processing capacity is increased. When the GHSV is equal to or less than the upper limit, the conversion rate of ethanol and acetaldehyde is improved.
The GHSV of ethanol and acetaldehyde in the intermediate gas or mixed gas is obtained by dividing the flow rate of ethanol and acetaldehyde in terms of standard conditions by the filling amount of the second catalyst (the volume of the catalyst layer).

The conversion of ethanol and acetaldehyde in step B3 is preferably over 30%, more preferably over 40%, even more preferably over 50%.
The "conversion rate of ethanol and acetaldehyde" in step B3 refers to the number of moles per unit time of ethanol and acetaldehyde in the intermediate gas or mixed gas supplied to the reactor in step B3. means the molar ratio of the number of moles of ethanol and acetaldehyde consumed per unit time. The number of moles per unit time of ethanol and acetaldehyde consumed in the reactor of step B3 is the number of moles per unit time of ethanol and acetaldehyde in the intermediate gas or the mixed gas supplied to the reactor of step B3. from the number of moles per unit time of ethanol and acetaldehyde in the 1,3-butadiene-containing gas discharged from the reactor in step B3.

The selectivity of 1,3-butadiene in the conversion reaction of step B3 is preferably greater than 60%, more preferably greater than 70%, and even more preferably greater than 80%. The “1,3-butadiene selectivity” in step B3 refers to the number of moles per unit time of ethanol and acetaldehyde consumed in the reactor in step B3, and ethanol converted to 1,3-butadiene. and the ratio (percentage) of the number of moles of acetaldehyde per unit time.

The yield of 1,3-butadiene in the conversion reaction in step B3 is preferably 40-90%, more preferably 50-90%. The “yield of 1,3-butadiene” in step B3 means “conversion rate of ethanol and acetaldehyde”דselectivity of 1,3-butadiene”.

Preferably, about 65-80% of the acetaldehyde is converted to 1,3-butadiene in step B3.
By-products that can be contained in the 1,3-butadiene-containing gas obtained in step B3 include ethylene, propylene, diethyl ether, ethyl acetate, butanol, hexanol, 1-butene, 2-butene, isobutene, pentene, pentadiene, Examples include hexene and hexadiene.

In the method for producing 1,3-butadiene of the present embodiment, the hydrogen concentration in the intermediate gas or the mixed gas in step B3 is controlled to less than 15% by volume. The hydrogen concentration is preferably less than 15% by volume, more preferably 10% by volume or less, and even more preferably 5% by volume or less. When the hydrogen concentration is less than the upper limit, the yield of 1,3-butadiene is improved.

An example of a method for controlling the hydrogen concentration is to set the yield of aldehyde in step B1 to the upper limit value or less. It can also be controlled by the dilution ratio in step A2.

In this embodiment, it is preferable to provide a hydrogen concentration reduction step (step B4) between steps B1 and B3 to control the hydrogen concentration in the intermediate gas or the mixed gas. Process B4 is not particularly limited, but includes, for example, one or more of the following processes B4-1 to B4-4.
Step B4-1: A hydrogen concentration reduction step of condensing a portion of the intermediate gas or the mixed gas to separate gas and liquid to reduce the hydrogen concentration in the intermediate gas or the mixed gas.
Step B4-2: A hydrogen concentration reduction step of diluting the intermediate gas or the mixed gas to reduce the hydrogen concentration in the intermediate gas or the mixed gas.
Step B4-3: A hydrogen concentration reduction step of gas-separating the intermediate gas or the mixed gas with a gas separator to reduce the hydrogen concentration in the intermediate gas or the mixed gas.
Step B4-4: A step of reducing the hydrogen concentration in the intermediate gas or the mixed gas by gas-liquid separation using a scrubber to reduce the hydrogen concentration in the intermediate gas or the mixed gas.

In step B4-1, gas-liquid separation is performed by condensing a part of the intermediate gas obtained in step B1 or the mixed gas obtained in step B2, and the hydrogen concentration in the intermediate gas or the mixed gas to reduce

By gas-liquid separation, it can be separated into a liquid containing ethanol and acetaldehyde and a gas containing hydrogen. In this case, the liquid containing ethanol and acetaldehyde is heated, vaporized again, and supplied to the second reactor as an intermediate gas or mixed gas. The separated hydrogen-containing gas may be used as it is for another application, and ethanol, acetaldehyde, and butadiene contained in trace amounts may be recovered by distillation or the like.
Conditions for gas-liquid separation for separating a gas containing hydrogen from an intermediate gas or mixed gas are preferably conditions of pressure of 0 to 1.0 MPaG and temperature of 0°C to 100°C.

In step B4-2, the intermediate gas obtained in step B1 or the mixed gas obtained in step B2 is diluted to reduce the hydrogen concentration in the intermediate gas or the mixed gas.

In step B4-2, based on the result of monitoring the hydrogen concentration in the intermediate gas obtained in step B1 or the mixed gas obtained in step B2 with a hydrogen analyzer, the hydrogen concentration is less than 15% by volume. diluent with diluent gas. Examples of the diluent gas include the diluent gas exemplified in step A2.

In step B4-3, the intermediate gas obtained in step B1 or the mixed gas obtained in step B2 is separated by a gas separator to reduce the hydrogen concentration in the intermediate gas or mixed gas.

Gas separators include, for example, cryogenic (cryogenic) separators, pressure swing adsorption (PSA) separators, membrane separation separators, temperature swing adsorption (TSA) separators, metal ion (e.g., copper ions) and organic ligands (e.g., 5-azidoisophthalic acid) are combined into a separator using a porous coordination polymer (PCP), and separation using amine absorption. It can be configured using one or two or more of the vessels and the like.

In step B4-4, the intermediate gas obtained in step B1 or the mixed gas obtained in step B2 is gas-liquid separated by a scrubber to reduce the hydrogen concentration in the intermediate gas or the mixed gas.

In the separation by a scrubber, the intermediate gas obtained in step B1 or the mixed gas obtained in step B2 is scrubbed with a solvent such as ethanol or acetaldehyde to obtain a liquid containing ethanol and acetaldehyde and a gas containing hydrogen. can be separated into In this case, a liquid containing ethanol, acetaldehyde, and a solvent is heated, vaporized again, and supplied to the second reactor as an intermediate gas or mixed gas.

The hydrogen analyzer is installed between the outlet of the first reactor in step B1 and the inlet of the second reactor in step B3, and the intermediate gas or the mixed gas supplied to the second reactor over time Analyze the hydrogen concentration in the When it is desired to analyze the hydrogen concentration in the mixed gas, a hydrogen analyzer is installed between the place where step B2 is performed and the entrance of the second reactor in step B3.
Examples of hydrogen analyzers include in-line hydrogen analyzers, thermal conductivity hydrogen analyzers, process mass spectrometers, and the like.
When both steps B4-1 and B4-2 are performed, step B4-2 is preferably performed after step B4-1. When both steps B4-2 and B4-4 are performed, step B4-2 is preferably performed after step B4-4. When all steps B4-1 to B4-4 are performed, it is preferable to perform the steps B4-4, B4-1, B4-3, and B4-2 in this order. That is, step B4-2 is preferably performed last.

In this embodiment, it is preferable to provide a step of supplying an inert gas (dilution step: step B5) before step B3 to control the inert gas concentration in the intermediate gas or the mixed gas.
In step B5, an inert gas is supplied to the intermediate gas or the mixed gas to obtain a source gas. The inert gas is supplied so that the content of the inert gas in the raw material gas is 5 to 50% by volume. As the inert gas, the same gas as the diluent gas in step A can be exemplified.

(Process C)
Step C includes at least one step selected from the group consisting of steps C1 to C4 below.
Step C1: The butenes (1-butene, 2-butene, isobutene) in the 1,3-butadiene-containing gas are dehydrogenated and converted to 1,3-butadiene.
Step C2: Hydrogen gas is separated from the 1,3-butadiene-containing gas by gas-liquid separation to obtain a 1,3-butadiene-containing liquid.
Step C3: The liquefied product of 1,3-butadiene-containing gas or the 1,3-butadiene-containing liquid is distilled to separate into ethylene-containing gas, 1,3-butadiene-containing effluent and acetaldehyde-containing liquid.
Step C4: The acetaldehyde-containing liquid is distilled and separated into an acetaldehyde-containing gas and a residual liquid containing water.

In general, 1-butene, 2-butene and isobutene are difficult to separate from 1,3-butadiene by distillation or the like. In step C1, 1-butene, 2-butene and isobutene are dehydrogenated and converted to 1,3-butadiene, thereby increasing the proportion of 1,3-butadiene. In the method for producing 1,3-butadiene of the present embodiment, the hydrogen concentration in the intermediate gas or the mixed gas is controlled to less than 15% by volume, so the production of 1-butene, 2-butene, and isobutene is suppressed. be done.

When both the process C1 and the process C3 are performed in the process C, the process C1 may be performed before the process C3, and the process C1 may be performed after the process C3.
In step C1, for example, the 1,3-butadiene-containing gas obtained in step B3 or the 1,3-butadiene-containing effluent obtained in step C3 is fed to a third reactor, and in the presence of a third catalyst, pressure 1-butene, 2-butene and isobutene are dehydrogenated under the conditions of −1.0 to 1.0 MPaG and a temperature of 200 to 550° C. to convert them to 1,3-butadiene.
As the embodiment of the third reactor in step C1, the same embodiments as those exemplified for the first reactor can be exemplified.

Any catalyst can be used as the third catalyst as long as it promotes the dehydrogenation reaction of 1-butene, 2-butene and isobutene, and examples thereof include molybdenum, tungsten, bismuth, tin, iron and nickel. Among them, molybdenum is preferable from the viewpoint of yield of 1,3-butadiene. A 3rd catalyst may be used individually by 1 type, and may use 2 or more types together.

The pressure during the dehydrogenation reaction in step C1 may be set in the range of -1.0 to 1.0 MPaG, preferably -0.5 to 0.5 MPaG, more preferably -0.3 to 0.3 MPaG. .
If the pressure in step C1 is at least the lower limit of the above range, the yield of 1,3-butadiene is improved. If the pressure in step C1 is equal to or lower than the upper limit of the above range, it is possible to suppress the decrease in yield of 1,3-butadiene due to excessive reaction.

The temperature during the dehydrogenation reaction in step C1 may be set in the range of 200 to 550°C, preferably 300 to 500°C, more preferably 300 to 450°C. If the temperature in step C1 is at least the lower limit of the above range, the yield of 1,3-butadiene is improved. If the temperature in step C1 is equal to or lower than the upper limit of the above range, it is possible to suppress the decrease in the yield of 1,3-butadiene due to excessive reaction.

In step C2, the 1,3-butadiene-containing gas obtained in step B3 or the 1,3-butadiene-containing gas after step C1 is subjected to gas-liquid separation to separate the hydrogen gas into 1,3- A butadiene-containing liquid is obtained. When the ethanol-containing gas, the intermediate gas, or the mixed gas is diluted with a diluent gas such as nitrogen gas in steps A2 and B4-2, the diluent gas is separated together with the hydrogen gas in step C2.
The conditions for the gas-liquid separation of the 1,3-butadiene-containing gas are preferably a pressure of 0 to 1.0 MPaG and a temperature of 0 to 100°C.

In step C3, the liquefied 1,3-butadiene-containing gas obtained in step B3, the liquefied 1,3-butadiene-containing gas after step C1, or the 1,3-butadiene-containing liquid after step C2 is added to the distillation column. Feed and distill. This separates the ethylene-containing gas, the 1,3-butadiene-containing effluent and the acetaldehyde-containing liquid. More specifically, for example, using a plate distillation column or a packed distillation column, an ethylene-containing gas is extracted from the top of the column, an acetaldehyde-containing liquid is extracted from the bottom of the column, and a 1,3-butadiene-containing effluent is extracted from the intermediate portion. pull out. In step C3, two distillation columns are used, the ethylene-containing gas is separated in the first distillation column, and the 1,3-butadiene-containing effluent and the acetaldehyde-containing liquid are separated in the second distillation column. good too.

Ethylene-containing gas includes propylene, methane, ethane, etc. in addition to ethylene. When the liquefied 1,3-butadiene-containing gas obtained in step B3 is distilled without performing step C1, hydrogen gas and diluent gas such as nitrogen gas are separated together with the ethylene-containing gas in step C3.
The acetaldehyde-containing liquid includes not only acetaldehyde but also ethanol, water, and the like.

When step C3 is performed without step C2, hydrogen gas is also separated in step C3 together with the ethylene-containing gas. Further, when the ethanol-containing gas, the intermediate gas, or the mixed gas is diluted with a diluent gas such as nitrogen gas in steps A2 and B4-2, the diluent gas is separated together with the ethylene-containing gas in step C3. be done.

In step C4, the acetaldehyde-containing liquid obtained in step C3 is supplied to a distillation column and separated into an acetaldehyde-containing gas and a residual liquid containing water.
When performing Steps C3 and C4 in Step C, the method is not limited to performing Steps C3 and C4 separately, and Steps C3 and C4 may be performed at once in one distillation column.

The content of acetaldehyde in the acetaldehyde-containing gas obtained in step C4 is preferably 10% by volume or more, more preferably 20% by volume or more, and even more preferably 40% by volume or more. If the content of acetaldehyde is at least the above lower limit, the content of by-products is small, so recovery of acetaldehyde and reuse of the acetaldehyde-containing gas are facilitated, improving economic efficiency.
The purity of the purified 1,3-butadiene obtained in step C is preferably 95.0% by mass or higher, more preferably 99.0% by mass or higher, and even more preferably 99.5% by mass or higher.
In the present embodiment, the purifying steps of steps C3 and C4 can provide a 1,3-butadiene- and acetaldehyde-containing gas with higher purity.

(Process D)
If the conversion reaction is continued in step B, carbon deposition (coking) will occur on the catalyst and the catalytic activity will decrease. In contrast, in step D, the catalyst in at least one of the two or more parallel reactors used in step B is regenerated while step B continues. Thereby, the catalyst can be regenerated without interrupting the production of 1,3-butadiene, and the yield of 1,3-butadiene is improved.

Step D includes at least one selected from the group consisting of Steps D1 to D3 below.
Step D1: While continuing Step B, supplying an oxygen-containing gas having an oxygen concentration of 0.01% by volume to 100% by volume to at least one reactor of the two or more parallel reactors, and to regenerate the catalyst by exhausting gas containing carbon dioxide from the
Step D2: Continuing Step B, removing the catalyst from at least one of the two or more parallel reactors and recharging the regenerated catalyst by contacting it with an oxygen-containing gas outside the reactor. Regenerate the catalyst.
Step D3: Continuing Step B, replacing the catalyst in at least one of the two or more parallel reactors with unused catalyst to regenerate the catalyst.

In Steps D1 and D2, the oxygen-containing gas is brought into contact with the catalyst, whereby the carbon deposited on the catalyst reacts with oxygen and is removed as carbon dioxide, thereby regenerating the catalyst. Even when sulfur components and nitrogen components adhere to the catalyst and the catalytic activity is lowered, they react with oxygen and are removed as sulfur oxides and nitrogen oxides, thereby regenerating the catalyst.
In Steps D1 to D3, the conversion reaction under the catalyst is continued in reactors other than the reactor in which the catalyst is regenerated.

In the catalyst regeneration step in step D, the reactor containing the catalyst to be regenerated may be purged with an inert gas such as nitrogen gas before and after the oxygen-containing gas is supplied. Specifically, it is inert so as not to affect the exposure of oxygen-containing gases or the gases used as raw materials in the next reaction process, such as residual hydrogen, oxygen, ethanol, acetaldehyde, butadiene, and by-products generated in each process. Supply gas. Specifically, an inert gas is supplied so that the produced butadiene and recoverable ethanol and acetaldehyde as raw materials are not lost by reacting with oxygen and being oxidized, and the residual gas in the reactor is expelled. In addition, since there is a danger of explosion if hydrogen remaining in the reactor is exposed to oxygen-containing gas, the danger of explosion is avoided by purging the reactor with an inert gas before supplying oxygen-containing gas. be able to. Nitrogen gas is preferred as the inert gas. In order to improve economic efficiency, the inert gas used for purging containing the residual gas may not only be discharged as it is, but may be reused by circulating it with a pump or the like. After separating the residual gas, it may be recycled. can be reused. Alternatively, the inert gas used for purging containing the residual gas may be sent to step C and separated from the residual gas together with hydrogen gas in step C2 or step C3. can be separated and reused. As a result, butadiene, ethanol, and acetaldehyde contained in the residual gas can be recovered, so that the yield of butadiene is further increased. Alternatively, the inert gas used for purging containing the residual gas is sent to step B, and the ethanol-containing gas used in step B1 or step B3, the intermediate gas, or the intermediate gas and the ethanol-containing gas are combined. It may be reused by being mixed with a mixed gas obtained by mixing. Thereby, the hydrogen concentration in step B1 can be reduced, and the generation of by-products in step B3 can be suppressed. From the viewpoint of cost reduction, in the 1,3-butadiene production apparatus 100, the gas used for purging is more preferably supplied from the diluent gas container 106 to the reactor through the pipe 24 or the pipe 37.

The oxygen concentration of the oxygen-containing gas is 0.01% to 100% by volume, preferably 1% to 100% by volume, more preferably 10% to 70% by volume, and further 10% to 50% by volume. Preferably, 10% to 30% by volume is particularly preferred. When the oxygen concentration of the oxygen-containing gas is equal to or higher than the lower limit of the above range, the catalytic activity is easily recovered and the yield of 1,3-butadiene is improved. If the oxygen concentration of the oxygen-containing gas is equal to or less than the upper limit of the above range, the oxygen concentration does not become excessive, the possibility of explosion can be reduced, and the catalyst can be regenerated.

Examples of the oxygen-containing gas include air, oxygen gas, and a gas obtained by diluting oxygen gas with a diluent gas. Examples of the diluent gas include rare gases such as nitrogen gas and argon gas.
As the oxygen-containing gas, a gas obtained by diluting oxygen gas with a diluent gas is preferable in that the oxygen concentration can be adjusted to a desired concentration. Air is preferable as the oxygen-containing gas in terms of availability.

The catalyst regeneration treatment in step D is performed on at least one of the first catalyst in step B1 and the second catalyst in step B3.
When regenerating the first catalyst in step B1, step D includes at least one selected from the group consisting of steps D11, D21 and D31 below.
Step D11: While continuing Step B, at least one first reactor of the two or more parallel first reactors is charged under conditions of a pressure of 0 to 1.0 MPaG and a temperature of 0 ° C. to 500 ° C. An oxygen-containing gas is supplied and a carbon dioxide-containing gas is exhausted from the first reactor to regenerate the first catalyst.
Step D21: Continuing Step B, removing the first catalyst from at least one first reactor of the two or more parallel first reactors and contacting the oxygen-containing gas outside the first reactor The regenerated first catalyst is recharged to regenerate the first catalyst.
Step D31: Continuing Step B, replacing the first catalyst in at least one first reactor of the two or more parallel first reactors with an unused first catalyst to regenerate the first catalyst. do.

In step D11, an oxygen-containing gas is supplied to at least one first reactor of the two or more parallel first reactors. In step D21, the first catalyst is removed from at least one first reactor of the two or more parallel first reactors and recharged with the regenerated first catalyst outside the first reactor. In step D31, the first catalyst of at least one first reactor of the two or more parallel first reactors is replaced with an unused first catalyst. In either case, the ethanol-containing gas continues to be supplied to the remaining parallel first reactors.
The first catalyst is regenerated in the first reactor of step D11, step D21 and step D31, and the activity of the first catalyst is restored. Continuous production of 1,3-butadiene is achieved by sequentially performing at least one catalyst regeneration treatment of step D11, step D21 and step D31 for each of the two or more parallel first reactors. The first catalyst in each first reactor can be regenerated without interruption.
As a result, the decrease in activity of the first catalyst in step B1 can be suppressed, and the yield of 1,3-butadiene is improved.

As an aspect of supplying the oxygen-containing gas to the first reactor in step D11, for example, the first reactor is disconnected from the production line and connected to a separately prepared regeneration treatment line to supply the oxygen-containing gas. . Alternatively, an oxygen-containing gas supply line and a carbon dioxide-containing gas discharge line may be added to the production line, and the oxygen-containing gas may be supplied to the first reactor on the production line.

The pressure during the catalyst regeneration treatment in step D11 may be set in the range of 0 to 1.0 MPaG, preferably 0 to 0.5 MPaG, more preferably 0 to 0.3 MPaG. When the pressure in step D11 is at least the lower limit of the above range, regeneration of the catalyst is sufficient and the yield of 1,3-butadiene is improved. If the pressure in step D11 is equal to or lower than the upper limit of the range, excessive oxidation reaction is easily suppressed, and the possibility of explosion is reduced.

The temperature during the catalyst regeneration treatment in step D11 may be set in the range of 0°C to 500°C, preferably 100°C to 450°C, more preferably 250°C to 400°C. When the temperature in step D11 is at least the lower limit of the above range, regeneration of the catalyst is sufficient and the yield of 1,3-butadiene is improved. If the temperature in step D11 is equal to or lower than the upper limit of the range, excessive energy consumption can be suppressed.
The preferred conditions of pressure and temperature during the catalyst regeneration treatment in step D21 are the same as the preferred conditions of pressure and temperature during the catalyst regeneration treatment in step D11.

In step D11, it is preferable to control the amount of oxygen in the first reactor based on the result of monitoring the oxygen concentration in the first reactor with an analyzer. This can improve the yield of 1,3-butadiene while reducing the possibility of explosion.
As a method for controlling the amount of oxygen in the first reactor, when the amount of oxygen is decreased, for example, the oxygen concentration of the oxygen-containing gas to be supplied is decreased, the amount of oxygen-containing gas supplied is decreased, For example, a method such as increasing the amount of gas emitted from the Conversely, when increasing the amount of oxygen, methods such as increasing the oxygen concentration of the oxygen-containing gas to be supplied, increasing the amount of oxygen-containing gas supplied, and decreasing the amount of gas discharged from the first reactor can be exemplified. .

When the catalytic activity of the first catalyst decreases, the ethanol conversion rate decreases, so the molar ratio (ethanol/acetaldehyde) in the intermediate gas supplied to the second reactor increases. Therefore, a decrease in catalytic activity of the first catalyst can be detected by monitoring the molar ratio (ethanol/acetaldehyde). In step D, step D11, step D21 and step D31 are performed based on the results of monitoring the molar ratio (ethanol/acetaldehyde) in the intermediate gas or mixed gas (source gas) supplied to the second reactor with an analyzer. It is preferable to implement one or more of them. It is preferable to carry out sequentially while performing at least one of step D11, step D21 and step D31, while analyzing the molar ratio (ethanol/acetaldehyde) in each step. As a result, the catalytic activity of the first catalyst can be efficiently recovered without excessively increasing the molar ratio (ethanol/acetaldehyde) in the intermediate gas or mixed gas (raw material gas) supplied to the second reactor. Therefore, the yield of 1,3-butadiene is improved.

In step D of regenerating the first catalyst, it is preferable to discharge the intermediate gas from the first reactor based on the result of monitoring the hydrogen concentration in the first reactor with an analyzer. This makes it easier to prevent the hydrogen concentration from becoming too high and reduces the possibility of explosion. Also, the first catalyst can be regenerated at an appropriate timing, and the yield of 1,3-butadiene is improved.
As an analyzer for monitoring the hydrogen concentration in the first reactor, for example, a process mass spectrometer can be exemplified.

When regenerating the second catalyst in step B3, step D includes at least one selected from the group consisting of step D12, step D22 and step D32 below.
Step D12: While continuing Step B, at least one of the two or more parallel second reactors is charged with a pressure of 0 to 1.0 MPaG and a temperature of 0 ° C. to 500 ° C. An oxygen-containing gas is supplied and a gas containing carbon dioxide is exhausted from the second reactor to regenerate the second catalyst.
Step D22: Continuing Step B, removing the second catalyst from at least one second reactor of the two or more parallel second reactors and contacting the oxygen-containing gas outside the second reactor. The regenerated second catalyst is recharged to regenerate the second catalyst.
Step D32: Continuing Step B, replacing the second catalyst in at least one second reactor of the two or more parallel second reactors with an unused second catalyst to regenerate the second catalyst. do.

In step D12, similarly to step D11, the oxygen-containing gas is supplied to at least one second reactor of the two or more parallel second reactors. In step D22, as in step D21, the second catalyst is removed from at least one second reactor of the two or more parallel second reactors, and the second catalyst regenerated outside the second reactor is regenerated. to fill. In step D32, as in step D31, the second catalyst in at least one of the two or more parallel second reactors is replaced with an unused second catalyst. In either case, the intermediate gas or mixed gas continues to be supplied to the remaining parallel second reactors.
In the second reactor of step D12, step D22 and step D32, the second catalyst is regenerated and the activity of the second catalyst is restored. Continuous production of 1,3-butadiene by sequentially performing one or more catalyst regeneration treatments of step D12, step D22 and step D32 for each of two or more parallel second reactors The second catalyst in each second reactor can be regenerated without interrupting the process. As a result, the decrease in activity of the second catalyst in step B3 can be suppressed, and the yield of 1,3-butadiene is improved.

As the aspect of supplying the oxygen-containing gas to the second reactor in step D12, the same aspect as the aspect of supplying the oxygen-containing gas to the first reactor exemplified in step D11 can be exemplified.
The pressure during the catalyst regeneration treatment in step D12 may be set in the range of 0 to 1.0 MPaG, preferably 0 to 0.5 MPaG, more preferably 0 to 0.3 MPaG. When the pressure in step D12 is at least the lower limit of the above range, regeneration of the catalyst is sufficient and the yield of 1,3-butadiene is improved. If the pressure in step D12 is equal to or lower than the upper limit of the range, excessive oxidation reaction is easily suppressed, and the possibility of explosion is reduced.

The temperature during the catalyst regeneration treatment in step D12 may be set in the range of 0°C to 500°C, preferably 200°C to 500°C, more preferably 300°C to 450°C. When the temperature in step D12 is at least the lower limit of the above range, regeneration of the catalyst is sufficient and the yield of 1,3-butadiene is improved. If the temperature in step D12 is equal to or lower than the upper limit of the range, excessive energy consumption can be suppressed.
The preferred conditions of pressure and temperature for the catalyst regeneration treatment in step D22 are the same as the preferred conditions of pressure and temperature for the catalyst regeneration treatment in step D12.

In step D12, based on the results of monitoring the oxygen concentration in the second reactor with an analyzer, the range of 0.01% to 100% by volume, 1% to 100% by volume, and 10% to 70% by volume. It is preferable to control the amount of oxygen in the second reactor in the range of 10% to 50% by volume or 10% to 30% by volume. This can improve the yield of 1,3-butadiene while reducing the possibility of explosion.
As the method for controlling the amount of oxygen in the second reactor, the same aspects as those exemplified as the method for controlling the amount of oxygen in the first reactor can be exemplified.

In step D of regenerating the second catalyst, it is preferable to discharge the crude product gas from the second reactor based on the results of monitoring the 1,3-butadiene concentration and hydrogen concentration in the second reactor with an analyzer. . It is also preferred to vent the crude product gas from the second reactor based on the results of monitoring the hydrogen concentration in the second reactor with an analyzer. As a result, the second catalyst can be regenerated at appropriate timing, and the yield of 1,3-butadiene is improved. Examples of analyzers for monitoring the 1,3-butadiene concentration and hydrogen concentration in the second reactor include process mass spectrometers and gas chromatography.

The method for producing 1,3-butadiene of the present embodiment includes Steps A to C described above and, if necessary, Step D. The present embodiment can be carried out by appropriately selecting and combining the configurations described in steps A to D. Hereinafter, the method for producing 1,3-butadiene of the present embodiment will be specifically described by showing an embodiment example.

FIG. 4 is a schematic diagram of a 1,3-butadiene production apparatus 100 (hereinafter also referred to as "production apparatus 100") of the present embodiment. It should be noted that the dimensions and the like of the drawings illustrated in the following description are only examples, and the present invention is not necessarily limited to them, and can be implemented with appropriate changes within the scope of not changing the gist of the present invention. .

The manufacturing apparatus 100 includes gas preparation means 1 , conversion means 2 and purification means 3 .
The gas preparation means 1 includes a raw material container 102 , a vaporizer 104 , and a dilution gas container 106 . The conversion means 2 comprises a first reactor 108 , a hydrogen concentration reducing device 109 and a second reactor 110 . The purification means 3 includes a gas-liquid separator 112 , a first distillation column 114 , a third reactor 116 , a second distillation column 118 and a recovery section 120 .

The raw material container 102 and the vaporizer 104 are connected by the pipe 10 . A flow rate indicator adjuster 11 is provided in the pipe 10 . Vaporizer 104 and first reactor 108 are connected by pipe 12 . The piping 12 is provided with a pressure indicator adjuster 14 for adjusting the flow rate based on the pressure in the vaporizer 104, a mixer 16, a heat exchanger 18, a temperature indicator adjuster 20, and a valve 22 in this order from the vaporizer 104 side. ing. Diluent gas container 106 is connected by pipe 24 between pressure indicator adjuster 14 and mixer 16 in pipe 12 . A flow indicator adjuster 26 is provided in the pipe 24 .

The two or more parallel first reactors 108 and the hydrogen concentration reduction device 109 are connected by a pipe 28 branched on the first reactor 108 side. A valve 30 is provided at each branched portion of the pipe 28 on the first reactor 108 side. The hydrogen concentration reducing device 109 and two or more parallel second reactors 110 are connected by a pipe 29 branched on the second reactor 110 side. A valve 32 is provided at each branch portion of the pipe 29 on the side of the second reactor 110 . An analyzer 34 is provided in the pipe 28 . Further, a pipe 36 is provided which branches from between the vaporizer 104 and the pressure indicator regulator 14 of the pipe 12 and is connected between the branch portion of the pipe 28 on the side of the second reactor 110 and the analyzer 34. . The pipe 36 is provided with a flow rate indicator adjuster 38 so that the flow rate of the pipe 36 can be adjusted based on the analysis result of the analyzer 34 . An analyzer 35 is provided in the pipe 29 . Further, a pipe 37 is provided which branches from between the diluent gas storage portion 106 and the flow indicator adjuster 26 of the pipe 24 and is connected between the hydrogen concentration reducing device 109 of the pipe 29 and the analyzer 35 . The pipe 37 is provided with a flow rate indicator adjuster 27 so that the flow rate of the pipe 37 can be adjusted based on the analysis result of the analyzer 35 . The hydrogen concentration reducing device 109 is a hydrogen concentration reducing device 109 in which a heat exchanger 130, a gas-liquid separator 132, and a vaporizer 138 are installed in this order when step B4-1 is performed (FIG. 5). The gas-liquid separator 132 is connected to the pipe 28 and the heat exchanger 130 is provided on the pipe 28 . The gas-liquid separator 132 is connected with a pipe 134 . The gas-liquid separator 132 and vaporizer 138 are connected by a pipe 136 . Vaporizer 138 is connected to pipe 29 . When performing step B4-3, a gas separator and a hydrogen concentration reduction device (not shown) equipped with a pipe for discharging gas containing hydrogen, and when performing step B4-4, a scrubber and a vaporizer in this order. It is a hydrogen concentration reduction device (not shown) installed in . Note that the hydrogen concentration reduction device may include any one or more of the above-described aspects.

Two or more parallel second reactors 110 and gas-liquid separators 112 are connected by connecting pipes 40 . A valve 42 is provided at each branch portion of the connecting pipe 40 on the side of the second reactor 110 , and a heat exchanger 44 is provided at a position closer to the gas-liquid separator 112 .
Gas-liquid separator 112 and first distillation column 114 are connected by pipe 46 . The pipe 46 is provided with a pump 48 and a level indicator adjuster 50 for adjusting the flow rate based on the liquid level in the gas-liquid separator 112 in this order from the gas-liquid separator 112 side.

A pipe 52 is connected to the top of the first distillation column 114 . Further, a pipe 54 that is connected to the gas phase portion of the gas-liquid separator 112 and merges with the pipe 52 is provided.
An intermediate portion of the first distillation column 114 and the third reactor 116 are connected by a pipe 56 .
The third reactor 116 and recovery section 120 are connected by a pipe 58 .

The bottom of first distillation column 114 and second distillation column 118 are connected by pipe 60 . A pipe 62 connects the top of the second distillation column 118 , the connecting portion of the pipe 28 to the pipe 36 and the analyzer 34 . A pipe 64 is connected to the bottom of the second distillation column 118 .

A method for producing 1,3-butadiene according to the first embodiment using the production apparatus 100 will be described below.
The ethanol feedstock is supplied from the raw material storage unit 102 to the vaporizer 104 through the pipe 10, and the ethanol feedstock is vaporized under the conditions of -1.0 MPaG to 1.0 MPaG and the temperature of -100°C to 200°C to contain ethanol. It is made into gas (process A1). Ethanol-containing gas is sent from the vaporizer 104 to the pipe 12 , and nitrogen gas (dilution gas) is joined from the diluent gas storage unit 106 through the pipe 24 and mixed by the mixer 16 . Then, the ethanol concentration of the ethanol-containing gas is adjusted within the range of 0.1% by volume to 100% by volume (step A2).

The ethanol-containing gas with adjusted ethanol concentration is heated by the heat exchanger 18 and supplied to two or more parallel first reactors 108 . In each first reactor 108, for example, the ethanol-containing gas is contacted with the first catalyst under conditions of a pressure of 0 to 1.0 MPaG and a temperature of 50° C. to 500° C., so that ethanol in the ethanol-containing gas is A portion is converted to acetaldehyde (step B1). An intermediate gas containing ethanol and acetaldehyde is sent from each first reactor 108 to the pipe 28 .

A part of the ethanol-containing gas obtained in the vaporizer 104 (step A1) is mixed with the intermediate gas through the pipe 36 to obtain a mixed gas (step B2). The analyzer 34 analyzes the molar ratio (ethanol/aldehyde) in the intermediate gas supplied to the second reactor 110 . Based on the result, the flow rate indicator adjuster 38 adjusts the flow rate of the ethanol-containing gas from the pipe 36, and adjusts the molar ratio (ethanol/aldehyde) of the mixed gas supplied to the second reactor 110 within the range of 1 to 100. (Step B2). Specifically, when the molar ratio (ethanol/aldehyde) decreases during operation of the manufacturing process, the flow rate of the ethanol-containing gas supplied from the pipe 36 is increased to increase the molar ratio (ethanol/aldehyde). can do. Conversely, when the molar ratio (ethanol/aldehyde) increases, the molar ratio (ethanol/aldehyde) can be decreased by reducing the flow rate of the ethanol-containing gas supplied from the pipe 36 .

The intermediate gas or the mixed gas is sent to the hydrogen concentration reduction device 109 . The intermediate gas or the mixed gas is separated into ethanol and acetaldehyde and hydrogen gas. Specifically, as shown in FIG. 5, it is cooled by the heat exchanger 130 and supplied to the gas-liquid separator 132 . Hydrogen gas is separated from the intermediate gas or the mixed gas in the gas-liquid separator 132 . Specifically, the liquid containing ethanol and acetaldehyde can be separated from the hydrogen gas by gas-liquid separation (step B4-1). In this case, a liquid containing ethanol and acetaldehyde is supplied to vaporizer 138 through pipe 136 . A liquid containing ethanol and acetaldehyde is heated by the vaporizer 138, vaporized again, and supplied to the second reactor 110 through the pipe 29 as the intermediate gas or mixed gas. Hydrogen gas separated by the gas-liquid separator 132 is processed outside through a pipe 134 .

The concentration of hydrogen in the intermediate gas or the mixed gas supplied to the second reactor 110 is analyzed by the analyzer 35 . Based on the result, the flow rate of the nitrogen gas (diluent gas) from the pipe 37 is adjusted by the flow indicator adjuster 27, and the hydrogen concentration in the intermediate gas or mixed gas supplied to the second reactor 110 is 15% by volume. Control to less than (step B4-2).
Also, the analyzer 35 analyzes the ethanol concentration in the intermediate gas or the mixed gas. Based on the result, the flow rate of the nitrogen gas (inert gas) from the pipe 37 is adjusted by the flow indicator adjuster 27, and the inert gas in the intermediate gas or mixed gas (raw material gas) supplied to the second reactor 110 The gas concentration is controlled to 5-50% by volume (step B5).

Feed gas is supplied to two or more parallel second reactors 110 . In each of the second reactors 110, for example, the source gas is brought into contact with a catalyst layer containing a second catalyst under conditions of a pressure of 0 to 1.0 MPaG and a temperature of 50° C. to 500° C. to produce the source gas. Ethanol and acetaldehyde in are converted to 1,3-butadiene (Step B3). A 1,3-butadiene-containing gas is delivered from each second reactor 110 to the connecting pipe 40 .

The 1,3-butadiene-containing gas is cooled by heat exchanger 44 and supplied to gas-liquid separator 112 . In the gas-liquid separator 112, hydrogen gas is separated from the 1,3-butadiene-containing gas by gas-liquid separation. Specifically, by gas-liquid separation, the 1,3-butadiene-containing gas is separated into hydrogen gas and nitrogen gas (diluent gas) and a 1,3-butadiene-containing liquid (step C2). The pump 48 is driven to supply the 1,3-butadiene-containing liquid from the gas-liquid separator 112 through the pipe 46 to the first distillation column 114, where the 1,3-butadiene-containing liquid is distilled. An ethylene-containing gas is extracted from the top of the first distillation column 114 to the pipe 52, an acetaldehyde-containing liquid is extracted from the bottom of the column to the pipe 60, and a 1,3-butadiene-containing effluent is extracted from the intermediate part to the pipe 56. Separate (step C3). The ethylene-containing gas drawn out to the pipe 52 is combined with the hydrogen gas and nitrogen gas (dilution gas) drawn out from the gas phase part of the gas-liquid separator 112 to the pipe 54 and treated as waste gas.

The 1,3-butadiene-containing effluent discharged through the pipe 56 is supplied to the third reactor 116, where the 1,3-butadiene-containing effluent is dehydrogenated in the presence of the third catalyst to produce 1,3- The butenes (1-butene, 2-butene, isobutene) in the butadiene-containing effluent are converted to 1,3-butadiene (step C1). Purified 1,3-butadiene is sent from the third reactor 116 to the recovery unit 120 through the pipe 58 and recovered.

The acetaldehyde-containing liquid extracted from the bottom of the first distillation column 114 to the pipe 60 is supplied to the second distillation column 118 and distilled. A water-containing residual liquid is extracted from the bottom of the second distillation column 118 to a pipe 64, and an acetaldehyde-containing gas is extracted from the top of the column to a pipe 62 (step C4). The acetaldehyde-containing gas extracted to the pipe 62 is mixed with the intermediate gas as described above (step B2). The residual liquid containing water extracted to the pipe 64 is treated as a waste liquid.

For example, the valves 22 and 30 on both sides of at least one first reactor 108 of the two or more parallel first reactors 108 are closed and disconnected from the production line. An oxygen-containing gas is supplied to the separated first reactor 108 under the conditions of a pressure of 0 to 1.0 MPaG and a temperature of 0° C. to 500° C., and a gas containing carbon dioxide is discharged from the first reactor 108. Regenerate the first catalyst. Alternatively, the first catalyst is taken out from the first reactor 108, and the first catalyst regenerated outside the first reactor 108 or an unused first catalyst is filled into the first reactor 108 to regenerate the first catalyst.
At this time, the conversion reaction from ethanol to acetaldehyde continues in the remaining first reactor 108 to continuously produce 1,3-butadiene (steps D11, D21, D31). After the catalyst regeneration treatment, the first reactor 108 is connected to the production line again, and the valves 22 and 30 on both sides are opened to restart the conversion reaction (step B1).

For example, the valves 32 and 42 on both sides of at least one second reactor 110 of the two or more parallel second reactors 110 are closed and disconnected from the production line. An oxygen-containing gas is supplied to the separated second reactor 110 under conditions of a pressure of 0 to 1.0 MPaG and a temperature of 0 ° C. to 500 ° C., and a gas containing carbon dioxide is discharged from the second reactor 110. Regenerate the second catalyst. Alternatively, the second catalyst is taken out from the second reactor 110, and the second catalyst regenerated outside the second reactor 110 or an unused second catalyst is filled into the second reactor 110 to regenerate the second catalyst.
At this time, in the remaining second reactor 110, the conversion reaction from ethanol and acetaldehyde to 1,3-butadiene is continued to continuously produce 1,3-butadiene (step D12, step D22, step D32 ). After the catalyst regeneration treatment, the second reactor 110 is connected to the production line again, and the valves 32 and 42 on both sides are opened to restart the conversion reaction (step B2).
In the present embodiment, any one of process D11, process D21, process D31, process D12, process D22, and process D32 may be performed, or two or more may be appropriately combined.

In addition, in the manufacturing apparatus 100 having the above configuration, the first catalyst is prevented from being mixed into the second reactor 110 in the route of the pipe 28 and the pipe 29 connecting the first reactor 108 and the second reactor 110. It is preferable to install a dust collector (not shown) to prevent this.
By installing such a dust collector, the conversion reaction from ethanol to acetaldehyde in the second reactor 110 can be suppressed, and the conversion to 1,3-butadiene by the second catalyst that requires ethanol is stabilized. can be effectively maintained.
Examples of the dust collector as described above include, but are not particularly limited to, a cyclone, a bag filter, or a packed bed filter.

Furthermore, in the production apparatus 100, in order to prevent the first catalyst or the second catalyst from flowing out to the rear stage side of the first reactor 108 or the second reactor 110, the rear stage side of each reactor, specifically, Preferably, a catalyst holding unit (not shown) is installed in the pipe 28, the pipe 29 and the connecting pipe 40.
By installing such a catalyst holding unit, the first catalyst and the second catalyst flowing out from the first reactor 108 or the second reactor 110 are prevented from accumulating in pipes other than these reactors. can. As a result, the conversion reaction of ethanol or ethanol and acetaldehyde to 1,3-butadiene occurs at a location other than each reactor, resulting in the production of carbon-containing substances and a decrease in the yield of 1,3-butadiene. can be suppressed.
Examples of the catalyst holding unit as described above include, but are not limited to, grid supports, perforated plates, and alumina balls.

As described above, in the method for producing 1,3-butadiene of the present embodiment, Steps A to C are performed. In particular, by performing step B4-1 or step 4-2, the hydrogen concentration in the intermediate gas or mixed gas supplied to the second reactor 110 is less than 15% by volume, the activity of the second catalyst is reduced, and side reactions occur. can be suppressed, and the yield of 1,3-butadiene is improved.
In addition, by performing step B5, the content of inert gas in the raw material gas supplied to the second reactor 110 can be made 5 to 50% by volume. Therefore, the concentration of ethanol in the raw material gas can be reduced, adhesion of by-products to the pipes can be suppressed, and a drop in the yield of 1,3-butadiene due to temperature drop can be suppressed.
Furthermore, by performing the step B5, the water vapor generated in the step B3 can be replaced with an inert gas, and when the step D is performed, the moisture remaining inside the reactor 110 rapidly vaporizes to destroy the second catalyst. can be prevented.

The method for producing 1,3-butadiene of the present invention is not limited to the embodiments described above, and the configurations described in each step can be appropriately combined. It is possible to appropriately replace the constituent elements in the above-described embodiments with well-known constituent elements without departing from the scope of the present invention.

For example, in the above-described embodiment, the case of adopting the two-step reaction represented by formula (1) and formula (2) as the conversion reaction from ethanol to 1,3-butadiene was described. ,3-butadiene may employ a one-step reaction represented by the following formula (3).
2CH ₃ CH ₂ OH→CH ₂ =CH-CH=CH ₂ +2H ₂ O+H ₂ (3)

When a one-step reaction is adopted as the method for producing 1,3-butadiene, the inert gas is supplied to the ethanol-containing gas.

EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[Examples 1 to 4, Comparative Example 1]
1,3-butadiene was produced using the production apparatus 100A described above. At this time, the conditions of step B3 (conversion step) were as follows. In addition, a connection pipe (stainless steel pipe) having one bent portion was applied downstream of the second reactor. The radius of curvature of the connecting pipe was set to 30 mm, the arithmetic mean roughness was set to 30 μm, and the inert gas content in the raw material gas was set as shown in Table 1.
- Inert gas: Nitrogen gas (purity 99%).
- The inner surface temperature of the connecting pipe at the bend: 190°C (463K).
Step B3 (conversion step): pressure 0.1 MPaG, temperature 350° C. (623 K), second catalyst: mixed catalyst of zirconium dioxide and silicon dioxide (ZrO ₂ (10 wt % for SiO ₂ )/SiO ₂ ).

1. Production of Catalyst First, 0.7 g of zirconium chloride oxide octahydrate (ZrCl ₂ O.8H ₂ O: manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was dissolved in 100 mL of water to prepare an aqueous solution. Next, this aqueous solution was added to 2.0 g of a porous carrier (silica porous particles manufactured by Fuji Silysia Chemical Co., Ltd., average particle size: 1.77 mm, average pore diameter: 10 nm, total pore volume: 1.01 mL /g, specific surface area: 283 m ² /g). Then, after stirring for 1 hour with an ultrasonic cleaner under atmospheric pressure, the aqueous solution was separated by filtration. The recovered porous material was dried at 110° C. for 4 hours and then calcined at 400° C. for 4.5 hours to produce a catalyst.

<Confirmation of adhesion of by-products>
A brown by-product adhering to the inner surface of each connecting pipe was visually observed, and the degree of adhesion of the brown by-product was evaluated based on the following evaluation criteria. Table 1 shows the results.
"Evaluation criteria"
A: Adhesion of brown by-product is not observed.
B: Some brown by-product adheres.
C: A brown by-product is attached.

As shown in Table 1, in Examples 1 to 4 to which the production method of the present invention was applied, the evaluation of confirmation of adhesion of by-products was "A" or "B", and adhesion of by-products to the inner surface of the pipe was confirmed to be suppressed. On the other hand, in Comparative Example 1 in which the content of the inert gas in the raw material gas was less than 5% by volume, the evaluation of confirmation of adhesion of by-products was "C", and adhesion of by-products to the inner surface of the pipe was confirmed. It is considered that this is because the content of inert gas in the raw material gas was small and the generation of by-products could not be suppressed.

[Experimental Examples 1 to 5]
1,3-Butadiene was produced under the same conditions as in Example 1 using the production apparatus 100A described above. However, the content of the inert gas in the raw material gas was 50% by volume, and the composition and thermal conductivity of the catalyst layer in each example were as shown in Table 2.

2. Evaluation of Catalyst Ethanol was converted to 1,3-butadiene (hereinafter also referred to as “BD”) using the catalyst layer of each experimental example, and the yield of 1,3-butadiene was determined.
Specifically, first, 1.0 g of the catalyst is packed in a stainless steel cylindrical reaction tube having a diameter of 1/2 inch (1.27 cm) and a length of 15.7 inches (40 cm) to form a reaction bed (catalyst layer). ) was formed. Next, the mixture was heated so that the reaction temperature (center temperature Kc of the reaction bed) was 350° C., and the reaction pressure (pressure of the reaction bed) was 0.1 MPa. The heating temperature Kr during the reaction was as shown in Table 2. In this state, the source gas was supplied to the reaction tube at a gas hourly space velocity (GHSV) of 1200 h ⁻¹ against the catalyst to obtain a product gas containing 1,3-butadiene. After 1 hour from the start of supply of the raw material gas, the generated gas was collected. The collected product gases were each analyzed by gas chromatography to determine the BD selectivity, raw material conversion, BD yield ([raw material conversion]×[BD selectivity]) and reaction retention rate. Table 2 shows the results.
The term “BD selectivity” is the percentage of the number of moles of the raw material (ethanol) consumed in the reaction using the catalyst, which is converted to BD. In addition, the "raw material conversion rate" is the percentage of the number of moles consumed of the raw material contained in the raw material gas.

As shown in Table 2, in Experimental Examples 1 to 4 in which the thermal conductivity of the catalyst layer is 0.1 to 250 W / m K, the conversion rate of the raw material is 68% or more, and the yield of BD is 50%. That was it. On the other hand, in Experimental Example 5 in which the thermal conductivity of the catalyst layer was less than 0.1 W/m·K, the raw material conversion rate was as low as 63%, and the yield of BD was also low. This is presumably because the catalyst layer had a low thermal conductivity of less than 0.1 W/m·K, which caused the temperature inside the reaction tube to drop. If the thermal conductivity of the catalyst layer exceeds 250 W/m·K, a local temperature rise occurs, overreaction proceeds, many by-products are produced, and the yield of BD decreases. Do you get it.

[Examples 5 to 9, Comparative Example 2]
1,3-Butadiene was produced under the same conditions as in Example 1 using the production apparatus 100A described above. However, the content of the inert gas in the raw material gas is 50% by volume, and the radius of curvature r R1 at the bend _R1 of the connection pipe and the inner surface temperature T _R1 of the connection pipe at the bend R1 are as shown in Table 3. bottom.

<Confirmation of adhesion of by-products>
A brown by-product adhering to the inner surface of each connecting pipe was visually observed, and the degree of adhesion of the brown by-product was evaluated based on the following evaluation criteria. Table 3 shows the results.
"Evaluation criteria"
A: Adhesion of brown by-product is not observed.
B: Some brown by-product adheres.
C: A brown by-product is attached.

As shown in Table 3, in Examples 5 to 9 to which the present invention is applied, the evaluation of confirmation of adhesion of by-products is "A" or "B", and adhesion of by-products to the inner surface of the pipe can be suppressed. was confirmed. On the other hand, in Comparative Example 2 in which the value of the radius of curvature r _R1 was less than 20 mm, the evaluation of confirmation of adhesion of by-products was "C", and adhesion of by-products to the inner surface of the pipe was confirmed. It is believed that this is because if the value of the radius of curvature r _R1 is less than 20 mm, it becomes difficult for the by-product to move inside the connecting pipe at the bent portion, and the by-product tends to adhere to the inner surface of the pipe. If a large amount of the by-product adheres to the inner surface of the piping, it may clog the piping.

[Experimental Examples 6 to 8]
<Confirmation of adhesion of by-products>
The following experiments were conducted using compounds (by-products) with different viscosities. By-products with different viscosities (mPa·s) were prepared as shown in Table 4. The inner surface of the connecting pipe having one bent portion R1 with the radius of curvature shown in Table 4 is heated to 190 ° C. (463 K), and 100 μL of the above byproduct is dropped into the flow path of the connecting pipe and adheres to the inner surface of the connecting pipe. A brown by-product was visually observed, and the degree of adhesion of the brown by-product was evaluated based on the following evaluation criteria. Table 4 shows the results.
"Evaluation criteria"
A: Adhesion of brown by-product is not observed.
B: Some brown by-product adheres.
C: A brown by-product is attached.

As shown in Table ₄ , the value ₍ r _R1 /μ _R1 ) is 0.04 mm/mPa s or more, the evaluation of confirmation of adhesion of by-products is "A" or "B", and adhesion of by-products to the inner surface of the pipe was confirmed to be suppressed. On the other hand, in Experimental Example 8, in which the radius of curvature r _R1 /the viscosity μ _R1 of the by-product is less than 0.04 mm/mPa·s, the evaluation of confirmation of adhesion of the by-product is “C”, and the by-product was confirmed to adhere to the inner surface of the pipe. This is because when the radius of curvature r _R1 /viscosity μ _R1 of the by-product is less than 0.04 mm/mPa·s, the by-product is less likely to move inside the connecting pipe at the bend and adhere to the inner surface of the pipe. Presumably because it makes it easier.

[Experimental Examples 9 to 12]
As a result of gas chromatography (GC) analysis of the by-product captured in the bypass 41 of the manufacturing apparatus 100A, it was found to contain δ-hexanolactone, 2,6-diisopropylphenol, and 1-adamantylmethyl ketone. Do you get it. The following experiments were performed using this captured by-product.

<Measurement of moving speed of by-product>
A connection pipe having an arithmetic mean roughness Ra ₄₀ (μm) shown in Table 5 and having one bend with a radius of curvature of 30 mm was prepared (Ra ₄₀ is the value of the inner surface of the connection pipe), and the inner surface temperature at the bend was Heated to 200° C. (473 K). 100 μL of the by-product captured by the bypass 41 was dropped into the flow path of the heated connecting pipe and left for 5 minutes. After that, the connecting pipe was tilted by 90°, and the moving distance of the droplet of the by-product after 15 seconds was measured to calculate the moving speed of the droplet of the by-product. Table 5 shows the results.

As shown in Table 5, in Experimental Examples 9 to 11 in which Ra ₄₀ was 1.02 μm or less, the movement speed of the by-product droplets was 1.2 mm/s or more. On the other hand, in Experimental Example 12 with Ra ₄₀ of 1.03 μm, the movement speed of the by-product droplets was 0.0 mm/s. From this, it was found that if Ra ₄₀ is more than 1.02 μm, the by-product stays in the bent portion of the connecting pipe and tends to adhere to the inner surface of the connecting pipe.

[Experimental Examples 13 to 15]
<Measurement of moving speed of by-product>
The following experiments were conducted using compounds (by-products) with different viscosities. By-products with different viscosities (mPa·s) were prepared as shown in Table 6. A connecting pipe having an inner surface arithmetic mean roughness Ra ₄₀ of 0.09 μm and a bending portion with a radius of curvature of 30 mm was prepared and heated so that the inner surface temperature at the bending portion was 190° C. (463 K). 100 μL of the by-product was dropped into the flow path of the heated connecting pipe and left for 5 minutes. After that, the connecting pipe was tilted by 90°, and the moving distance of the droplet of the by-product after 15 seconds was measured to calculate the moving speed of the droplet of the by-product. Table 6 shows the results.

As shown in Table 6, the value obtained by dividing the arithmetic mean roughness Ra ₄₀ of the inner surface of the connecting pipe by the viscosity μ ₄₀ of the by-product (Ra ₄₀ /μ ₄₀ ) is 0.0001 μm/mPa s or more. In Examples 13 and 14, the moving speed of the by-product droplets was 2.0 mm/s or more. On the other hand, in Experimental Example 15, in which Ra ₄₀ /μ ₄₀ is less than 0.0001 μm/mPa·s, the movement speed of the by-product droplets was 0.0 mm/s. From this, it was found that when Ra ₄₀ /μ ₄₀ is less than 0.0001 μm/mPa·s, the by-product stays in the bent portion of the connecting pipe and easily adheres to the inner surface of the connecting pipe.

According to the present invention, it was found that the generation of by-products can be suppressed, and the adhesion of the generated by-products to the inner surface of the pipe can be suppressed.

1... gas preparation means, 2, 2A... conversion means, 3... purification means, DESCRIPTION OF SYMBOLS 136... Piping, 11,26,27,38...Flow indicator adjuster, 14... Pressure indicator adjuster, 16... Mixer, 18,44,130... Heat exchanger, 20... Temperature indicator adjuster, 22,30,32 , 42, 43, 45... valves, 34, 35... analyzer, 40... connection pipe, 41... bypass, 48... pump, 50... level indicator adjuster, 100, 100A... 1,3-butadiene production apparatus, 102... Raw material storage unit 104, 138 Vaporizer 106 Diluent gas storage unit 108 First reactor 109 Hydrogen concentration reducing device 110 Second reactor 111 Catalyst layer 112, 132 Gas Liquid separator, 114...first distillation column, 116...third reactor, 118...second distillation column, 120...recovery section

Claims (24)

A method for producing 1,3-butadiene, which continuously produces 1,3-butadiene from a raw material gas containing ethanol, acetaldehyde, and an inert gas,
A conversion step of contacting the raw material gas with a catalyst layer containing a catalyst to convert ethanol and acetaldehyde in the raw material gas to 1,3-butadiene,
A method for producing 1,3-butadiene, wherein the content of the inert gas in the raw material gas is 5 to 50% by volume with respect to the total volume of the raw material gas. 1,3- according to claim 1, wherein the total amount of the ethanol content and the acetaldehyde content in the source gas is 40 to 95% by volume with respect to the total mass of the source gas. A method for producing butadiene. 3. The method for producing 1,3-butadiene according to claim 1, further comprising a dilution step of diluting the intermediate gas containing the ethanol and the acetaldehyde with the inert gas. 1 according to any one of claims 1 to 3, wherein the ratio of the content of ethanol in the source gas to the content of acetaldehyde in the source gas (ethanol/acetaldehyde ratio) is 1 to 100. , 3-butadiene production method. The method for producing 1,3-butadiene according to any one of claims 1 to 4, wherein the catalyst layer has a thermal conductivity of 0.1 to 250 W/m·K. the catalyst layer comprises a diluent;
The method for producing 1,3-butadiene according to any one of claims 1 to 5, wherein the diluent has a higher thermal conductivity than the catalyst. A 1,3-butadiene production apparatus for continuously producing 1,3-butadiene,
a conversion means and a purification means;
The conversion means contacts an ethanol-containing gas containing ethanol with a catalyst layer containing a catalyst, converts the ethanol in the ethanol-containing gas into 1,3-butadiene, and converts the ethanol-containing gas into 1,3-butadiene. Equipped with a reactor for producing gas,
The purification means comprises a distillation column for purifying the crude gas obtained by the conversion means,
A connecting pipe that connects the reactor and the distillation column,
The connection pipe has at least one bend,
The apparatus for producing 1,3-butadiene, wherein the curved portion has a radius of curvature of 20 mm or more. 8. The apparatus for producing 1,3-butadiene according to claim 7, wherein the inner surface of said connecting pipe has an arithmetic average roughness of 1.02 μm or less. The apparatus for producing 1,3-butadiene according to claim 7 or 8, wherein the inner surface of the connecting pipe is coated with an organic compound having 6 to 12 carbon atoms. 10. The apparatus for producing 1,3-butadiene according to any one of claims 7 to 9, wherein the connecting pipe has at least one bypass, and the bypass is removable. The apparatus for producing 1,3-butadiene according to any one of claims 7 to 10, wherein the catalyst layer has a thermal conductivity of 0.1 to 250 W/m·K. the catalyst layer comprises a diluent;
The apparatus for producing 1,3-butadiene according to any one of claims 7 to 11, wherein the diluent has a higher thermal conductivity than the catalyst. The apparatus for producing 1,3-butadiene according to any one of claims 7 to 12, comprising two or more heating means for heating the reactor. When the length of the catalyst layer in the reactor in the flow direction of the source gas is L,
A first area is defined as a region from the inlet side of the raw material gas to L/3 in the catalyst layer,
A region from the first area to L/3 is defined as a second area,
A region from the second area to L/3 is defined as a third area,
Let k1 be the catalytic activity of the catalyst filled in the first area, and w1 be the total mass of the catalyst filled in the first area,
Let k2 be the catalytic activity of the catalyst filled in the second area, and w2 be the total mass of the catalyst filled in the second area,
When the catalytic activity of the catalyst packed in the third area is k3 and the total mass of the catalyst packed in the third area is w3,
The apparatus for producing 1,3-butadiene according to any one of claims 7 to 13, which satisfies the following formula (a).
k1×w1<k2×w2<k3×w3 (a) A 1,3-butadiene production apparatus for continuously producing 1,3-butadiene from a raw material gas containing ethanol, acetaldehyde, and an inert gas,
a conversion means and a purification means;
The conversion means contacts the raw material gas with a catalyst layer containing a catalyst, converts ethanol and acetaldehyde in the raw material gas into 1,3-butadiene, and produces a crude product gas containing the 1,3-butadiene. with a reactor of
The purification means comprises a distillation column for purifying the crude gas obtained by the conversion means,
The content of the inert gas in the raw material gas is 5 to 50% by volume with respect to the total volume of the raw material gas,
A connecting pipe that connects the reactor and the distillation column,
The connection pipe has at least one bend,
The apparatus for producing 1,3-butadiene, wherein the curved portion has a radius of curvature of 20 mm or more. 16. The 1,3- Butadiene manufacturing equipment. 17. The apparatus for producing 1,3-butadiene according to claim 15 or 16, further comprising a diluting device that dilutes the intermediate gas containing the ethanol and the acetaldehyde with the inert gas in the preceding stage of the reactor. 18. The apparatus for producing 1,3-butadiene according to any one of claims 15 to 17, wherein the inner surface of the connecting pipe has an arithmetic average roughness of 1.02 µm or less. The apparatus for producing 1,3-butadiene according to any one of claims 15 to 18, wherein the inner surface of the connecting pipe is coated with an organic compound having 6 to 12 carbon atoms. The apparatus for producing 1,3-butadiene according to any one of claims 15 to 19, wherein the connection piping has at least one bypass, and the bypass is removable. The apparatus for producing 1,3-butadiene according to any one of claims 15 to 20, wherein the catalyst layer has a thermal conductivity of 0.1 to 250 W/m·K. the catalyst layer comprises a diluent;
The apparatus for producing 1,3-butadiene according to any one of claims 15 to 21, wherein the thermal conductivity of the diluent is higher than the thermal conductivity of the catalyst. The apparatus for producing 1,3-butadiene according to any one of claims 15 to 22, comprising two or more heating means for heating the reactor. When the length of the catalyst layer in the reactor in the flow direction of the source gas is L,
A first area is defined as a region from the inlet side of the raw material gas to L/3 in the catalyst layer,
A region from the first area to L/3 is defined as a second area,
A region from the second area to L/3 is defined as a third area,
Let k1 be the catalytic activity of the catalyst filled in the first area, and w1 be the total mass of the catalyst filled in the first area,
Let k2 be the catalytic activity of the catalyst filled in the second area, and w2 be the total mass of the catalyst filled in the second area,
When the catalytic activity of the catalyst packed in the third area is k3 and the total mass of the catalyst packed in the third area is w3,
The apparatus for producing 1,3-butadiene according to any one of claims 15 to 23, which satisfies the following formula (a).
k1×w1<k2×w2<k3×w3 (a)

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