JP2023031384A - Method for producing butadiene - Google Patents

Abstract

To provide a method for producing butadiene capable of producing butadiene while reducing carbon dioxide emissions.SOLUTION: A first reactor 3 and a second reactor 4 used in the method for producing butadiene of the present invention comprise a plurality of reaction tubes Ra and Rb each filled with a catalyst. When a reaction process in which the raw material gas is passed at a temperature of 300 to 420°C through some reaction tubes of Ra and Rb, and a regeneration process in which a regeneration gas for regenerating the catalyst is passed through the remaining reaction tubes at a temperature of 420 to 550°C are alternately performed, the contact frequency of the raw material gas and the regeneration gas with respect to the catalyst, which is represented by the following formula (1), is set to 500 to 50000. Contact frequency=(flow rate of raw material gas and regeneration gas [kg/hr]×pressure in the reaction tube [MPaA])/(area occupied by the catalyst in the cross section at the center in the longitudinal direction of the reaction tube [m2]×outer diameter of the reaction tube[m]] (1).SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for producing 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 butadiene, for example, a method of converting ethanol into acetaldehyde in the presence of a catalyst and then converting ethanol and acetaldehyde into butadiene is known (see, for example, Patent Document 1).

Japanese Patent Publication No. 2017-532318

However, according to the study of the present inventor, in the conventional manufacturing method, the heat (energy) used or generated in each process is not effectively reused, so additional energy must be input, and this energy is used. It has been found that there is a limit to reducing carbon dioxide emissions due to the carbon dioxide produced during production.
The present invention has been made in view of such circumstances, and an object thereof is to provide a method for producing butadiene capable of producing butadiene while reducing carbon dioxide emissions.

Such objects are achieved by the present invention described below.
(1) The method for producing butadiene of the present invention includes a first reactor that converts ethanol to acetaldehyde, an inorganic gas separator that separates an inorganic gas by-produced in the first reactor, and ethanol and acetaldehyde that are converted to butadiene. A method for producing butadiene by passing a raw material gas through the second reactor in order,
each reactor comprises a plurality of reaction tubes connected in parallel and filled with a catalyst;
A reaction process in which the raw material gas is passed through some of the reaction tubes out of the plurality of reaction tubes at a temperature of 300 to 420 ° C., and a regeneration gas for regenerating the catalyst is supplied to the remaining reaction tubes at 420 to 550 ° C. in alternating with the regeneration process passing through at a temperature of
It is characterized in that the contact frequency represented by the following formula (1) of the raw material gas and the regeneration gas with respect to the catalyst is set to 500 to 50,000.
Contact frequency = (flow rate of raw material gas and regeneration gas [kg/hr] x pressure in reaction tube [MPaA])/(area occupied by catalyst in cross section at the center in the longitudinal direction of reaction tube [m ² ] x reaction tube Outer diameter [m]) (1)

(2) In the method for producing butadiene of the present invention, the conditions for passing the raw material gas through the inorganic gas separator are preferably a temperature of 3 to 15° C. and a pressure of 0.5 to 5 MPaG.
(3) The method for producing butadiene of the present invention includes, between the reaction process and the regeneration process, a replacement process of passing an inert gas through the reaction tube,
Time of the reaction process>(temperature difference between the reaction process and the regeneration process)/(heating rate from the reaction process to the regeneration process) + (temperature difference between the regeneration process and the reaction process)/( It is preferable to adjust the temperature increase rate and the temperature decrease rate so as to satisfy the following relationship: temperature drop rate from the regeneration process to the reaction process) + (time of the replacement process) + (time of the regeneration process). .

(4) The method for producing butadiene of the present invention further includes a heating mechanism for heating the raw material gas in the reaction process,
The heating mechanism preferably includes at least one selected from a heat exchanger, an electric heater, and a microwave irradiator that exchange heat with the heat medium transferred in the heat medium transfer line.
(5) In the method for producing butadiene of the present invention, the heat medium transfer line includes a first branch line and a second branch line that rejoins after branching off from the first branch line,
It is preferable that the transfer direction of the heat medium in the first branch line and the transfer direction of the heat medium in the second branch line are opposite to each other with respect to the reaction tube.

(6) In the method for producing butadiene of the present invention, the first branch line and the second branch line are respectively inside the reaction tube, outside the reaction tube and inside the reactor, and outside the reactor. is preferably provided in at least one selected from
(7) In the method for producing butadiene of the present invention, the heat medium is the source gas after passing through the reaction tube,
The heat medium transfer line also functions as a raw material gas transfer line for transferring the raw material gas, and the heat exchanger connects the raw material gas after passing through the reaction tube and the raw material gas before passing through the reaction tube. It is preferable to perform heat exchange with the raw material gas.

(8) In the method for producing butadiene of the present invention, it is preferable that a pressure booster for increasing the pressure of the raw material gas is provided on the downstream side of the reaction tube.
(9) The method for producing butadiene of the present invention further includes a second heating mechanism for heating the regeneration gas in the regeneration process,
The second heating mechanism is provided separately from the heating mechanism, and is a second heat exchanger and a second electric heater that exchange heat with the second heat medium transferred in the second heat medium transfer line. and a second microwave irradiator.

(10) The method for producing butadiene of the present invention further includes a third heating mechanism for heating the catalyst after the reaction process is finished and before the regeneration process is started,
The third heating mechanism is provided separately from the heating mechanism and the second heating mechanism, and performs heat exchange with a third heat medium transferred in a third heat medium transfer line. It is preferable to include at least one selected from a vessel, a third electric heater and a third microwave irradiator.
(11) The method for producing butadiene of the present invention further comprises a cooling mechanism for cooling the catalyst after the regeneration process is finished and before the reaction process is started,
The cooling mechanism preferably includes at least one selected from a fourth heat exchanger and a cooler that exchange heat with the refrigerant transferred in the refrigerant transfer line.

(12) In the method for producing butadiene of the present invention, the regeneration process preferably further includes a preheated regeneration gas supply mechanism for supplying the preheated regeneration gas to the reaction tube.
(13) In the method for producing butadiene of the present invention, preheated gas is used to adjust the temperature in the reaction tube,
The gases are a first gas used in the reaction process, a second gas used in a temperature raising process from the reaction process to the regeneration process, and a second gas used in the regeneration process, which are different in gas composition from each other. a third gas and a fourth gas used in a temperature-lowering process from the regeneration process to the reaction process;
Heat exchange is preferably performed between the first gas and the third gas, and heat exchange is performed between the second gas and the fourth gas.

According to the present invention, butadiene can be produced continuously and stably while reducing carbon dioxide emissions.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the whole manufacturing apparatus used by 1st Embodiment of the manufacturing method of butadiene of this invention. FIG. 2 is a schematic diagram (partially omitted) showing the configuration around the reactor. It is a schematic diagram showing the configuration of a heating mechanism that heats the raw material gas. It is a schematic diagram showing the configuration of a heating mechanism that heats the raw material gas. It is a schematic diagram showing the configuration of a heating mechanism that heats the raw material gas. FIG. 2 is a schematic diagram showing part of a production apparatus used in a second embodiment of the method for producing butadiene of the present invention. FIG. 3 is a schematic diagram showing part of a production apparatus used in a third embodiment of the method for producing butadiene of the present invention. FIG. 4 is a schematic diagram showing the configuration of a second heating mechanism that heats the regeneration gas;

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing butadiene of the present invention will now be described in detail based on preferred embodiments shown in the accompanying drawings.
<First embodiment>
First, a first embodiment of the method for producing butadiene of the present invention will be described.
FIG. 1 is a schematic diagram showing the entire production apparatus used in the first embodiment of the method for producing butadiene of the present invention.
The dimensions and the like in the drawings illustrated in the following description are examples, and the present invention is not necessarily limited to them, and can be implemented with appropriate modifications within the scope of not changing the gist of the invention.

The manufacturing apparatus 1 shown in FIG. 1 mainly includes a raw material tank 2, a first reactor 3, a second reactor 4, a purification section 5, and a second It has a first line L1, a second line L2 connecting the first reactor 3 and the second reactor 4, and a third line L3 connecting the second reactor 4 and the refining section 5.
In this specification, the upstream side with respect to the flow direction of the fluid (liquid or gas) is also simply referred to as the "upstream side", and the downstream side is simply referred to as the "downstream side".

The first line L1 is connected to the raw material tank 2 at one end thereof. Ethanol feedstock is supplied and stored in the raw material tank 2 .
The ethanol feedstock contains ethanol as an essential component, and may contain other components such as water as long as the effects of the present invention are not impaired. The amount of ethanol contained in the ethanol feedstock is preferably 80% by mass or more, more preferably 90% by mass or more, and preferably 93% by mass or more, relative to the total mass of the ethanol feedstock. More preferred. The upper limit of the amount of ethanol is theoretically 100% by weight.

The ethanol feedstock is not particularly limited, but may be, for example, ethanol derived from fossil fuels such as shale gas or petroleum, or biomass-derived ethanol (bioethanol) such as plants, animals, or garbage. good too. Among them, bioethanol is preferable as the ethanol feedstock from the viewpoint that the content of impurities such as nitrogen compounds and sulfur compounds is small and the catalyst is less likely to deteriorate.

On the other hand, the first line L1 is connected to the first reactor 3 at the other end. In the first reactor 3, ethanol is converted (converted) into acetaldehyde as shown in the following formula (A).
_{CH3CH2OH- > CH3CHO} + _H2 ... (A)
The first reactor 3 includes a plurality of (two in this embodiment) reaction tubes Ra and Rb connected in parallel (see FIG. 2).
After being branched, the first line L1 is connected to inlet ports of the reaction tubes Ra and Rb, respectively. Although not shown, a channel opening/closing device such as a valve is arranged in the middle of the branch line of the first line L1.

Each reaction tube Ra, Rb is filled with a first catalyst to form a reaction bed (catalyst layer). Examples of the form of the reaction bed include fixed bed, moving bed, fluidized bed and the like.
The first catalyst may promote the conversion reaction from ethanol to acetaldehyde. Specific examples of the first catalyst include a mixture of chromium oxide and copper oxide, zinc oxide alone, and a mixture of copper oxide and silicon oxide. In addition, the 1st catalyst may use these 1 type individually, and may use 2 or more types together.
Among them, the first catalyst is preferably a mixture of copper oxide and silicon oxide from the viewpoint of high conversion rate from ethanol to acetaldehyde.

A vaporizer 7 and a temperature control device TC1 are arranged in order from the upstream side in the middle of the first line L1.
In the vaporizer 7, the ethanol feedstock is heated and vaporized to generate an ethanol-containing gas (raw material gas).
The pressure during vaporization of the ethanol feedstock is preferably -1.0 to 1.0 MPaG, more preferably -0.5 to 0.5 MPaG, and -0.3 to 0.3 MPaG. is more preferred. If the pressure at the time of vaporization of the ethanol feedstock is within the above range, the ethanol feedstock can be efficiently vaporized, and the volume of the ethanol-containing gas does not become excessive when vaporized, thereby suppressing an increase in the size of machinery and equipment. be able to.

The temperature at which the ethanol feedstock is vaporized is preferably -100 to 200°C, more preferably 0 to 150°C, even more preferably 25 to 100°C. If the temperature at which the ethanol feedstock is vaporized is within the above range, the ethanol feedstock can be efficiently vaporized, and excessive heating of the ethanol feedstock becomes unnecessary.
An inert gas tank 6 is connected to the vaporizer 7 via a fourth line L4. An inert gas is supplied and stored in the inert gas tank 6 .
If necessary, an inert gas is supplied to the vaporizer 7 and mixed with the produced ethanol-containing gas.

The concentration of ethanol contained in the ethanol-containing gas is preferably 0.1 to 100% by volume, more preferably 10 to 100% by volume, even more preferably 20 to 100% by volume. If the concentration of ethanol contained in the ethanol-containing gas is within the above range, the yield of butadiene can be increased.
As the inert gas (diluent gas), a gas that does not adversely affect the conversion reaction from ethanol to butadiene is suitable. Specific examples of such inert gas include nitrogen gas, rare gas such as argon gas, and carbon dioxide gas. In addition, these inert gases may be used individually by 1 type, and may use 2 or more types together. Among them, nitrogen gas and argon gas are preferable as the inert gas because they are inexpensive and readily available.

Part of the obtained ethanol-containing gas is supplied to the first reactor 3 via the temperature control device TC1, and part of it is supplied to the mixer 10 described later via the fifth line L5. Alternatively, the ethanol-containing gas can be supplied to the mixer 10 from a raw material tank independent of the raw material tank 2 .
The temperature controller TC1 heats the ethanol-containing gas.
The temperature at this time is set according to the conversion reaction from ethanol to acetaldehyde by the first catalyst (the type of the first catalyst), and is not particularly limited, but is preferably 100 to 500 ° C., and is preferably 200 to 450 ° C. more preferably 300 to 420°C. In this case, it is possible to increase the conversion rate of ethanol to acetaldehyde while reducing excessive energy consumption (that is, carbon dioxide emissions).

The conversion rate from ethanol to acetaldehyde in the first reactor 3 is preferably 30-70%, more preferably 40-60%.
Here, the “conversion rate to aldehyde” refers to the number of moles of ethanol contained in the ethanol-containing gas supplied to the first reactor 3 per unit time consumed in the first reactor 3 (first catalyst). means the ratio (percentage) of the number of moles of ethanol per unit time.
The number of moles per unit time of ethanol consumed in the first reactor 3 is calculated from the number of moles per unit time of ethanol contained in the ethanol-containing gas supplied to the first reactor 3. It is calculated by subtracting the number of moles per unit time of ethanol contained in the exhaust gas (hereinafter also referred to as "intermediate gas") discharged from 3.

The selectivity of acetaldehyde in the conversion reaction in the first reactor 3 is preferably 85% or higher, more preferably 90% or higher.
Here, the "acetaldehyde selectivity" is the ratio (percentage) of the number of moles per unit time of ethanol converted to acetaldehyde to the number of moles per unit time of ethanol consumed in the first reactor 3. means.
By-products that may be contained in the intermediate gas discharged from the first reactor 3 include, for example, methane, ethane, ethylene, diethyl ether, acetone, crotonaldehyde, butyraldehyde, ethyl acetate, and acetic acid. mentioned.

The intermediate gas (raw material gas) discharged from the first reactor 3 is supplied to the second reactor 4 via the second line L2. In the second reactor 4, ethanol and acetaldehyde contained in the intermediate gas are converted to butadiene (1,3-butadiene) as shown in the following formula (B).
_{CH3CH2OH + CH3CHO}
→CH ₂ =CH-CH=CH ₂ +2H ₂ O (B)
The second reactor 4 includes a plurality of (two in this embodiment) reaction tubes Ra and Rb connected in parallel (see FIG. 2).
After branching, the second line L2 is connected to the inlet ports of the reaction tubes Ra and Rb, respectively. Although not shown, a channel opening/closing device such as a valve is arranged in the middle of the branch line of the second line L2.

Each reaction tube Ra, Rb is filled with a second catalyst to form a reaction bed (catalyst layer). Examples of the form of the reaction bed include fixed bed, moving bed, fluidized bed and the like.
The second catalyst may promote the conversion reaction of ethanol and acetaldehyde to butadiene. Specific examples of the second catalyst include tantalum, zirconium, titanium, cerium, niobium, hafnium, magnesium, zinc and silicon. The second catalyst may be used alone or in combination of two or more.
Among them, zirconium and hafnium are preferable as the second catalyst from the viewpoint of a high yield of butadiene.
Examples of the state of the second catalyst include simple element, oxide, and chloride. Examples of usage modes include a mode in which the second catalyst is supported on a carrier and a mode in which two or more of them are used as a mixture.

In the middle of the second line L2, in order from the upstream side, there are a temperature control device TC2, a booster 8, a temperature control device TC3, a hydrogen separator (inorganic gas separator) 9, a mixer 10, and a temperature control device. A device TC4 is arranged.
The temperature controller TC2 cools the intermediate gas.
The pressure of the intermediate gas after cooling is increased by passing through the booster 8 . As a result, the amount of intermediate gas that can be processed by the hydrogen separator 9 at one time can be increased. In addition, the hydrogen separator 9 can separate hydrogen (inorganic gas) with less accompanying acetaldehyde. At this time, the temperature of the intermediate gas rises as the pressure rises.
The booster 8 is, for example, a centrifugal compressor, a turbo compressor such as an axial compressor, a reciprocating compressor (reciprocating compressor), a diaphragm compressor, a single screw compressor, a twin screw compressor, a scroll It can be composed of a compressor, a rotary compressor, a rotary piston type compressor, a positive displacement compressor such as a slide vane type compressor, a roots blower (two-leaf blower) capable of handling low pressure, a centrifugal blower, and the like.

The temperature controller TC3 cools the intermediate gas again.
The intermediate gas after cooling passes through the hydrogen separator 9 . As described above, hydrogen is mixed in the intermediate gas produced in the first reactor 3 , so this hydrogen is removed by the hydrogen separator 9 . This makes it possible to prevent or suppress inhibition of the conversion reaction from ethanol and acetaldehyde to butadiene in the second reactor 4 . Also, in the inorganic gas separator 12, hydrogen (inorganic gas) can be separated with less entrainment of butadiene.
The concentration of hydrogen contained in the intermediate gas after passing through the hydrogen separator 9 is preferably 10% by volume or less, more preferably 5% by volume or less, and 1% by volume with respect to the entire intermediate gas. It is more preferably below, and may be 0% by volume.

The hydrogen separator 9 is composed of, for example, a gas-liquid separator. In the hydrogen separator 9, it is separated into a liquid containing ethanol and acetaldehyde and a gas containing hydrogen. In this case, a liquid containing ethanol and acetaldehyde is heated, re-vaporized and supplied downstream as an intermediate gas.
The temperature during gas-liquid separation is preferably 3 to 15°C, more preferably 5 to 10°C. The pressure during gas-liquid separation is preferably 0.5 to 5 MPaG, more preferably 1 to 3 MPaG. Hydrogen is efficiently separated by gas-liquid separation under such conditions.
The gas-liquid separator can be composed of, for example, a simple container, a swirling flow separator, a centrifugal separator, a surface tension separator, or the like.

The intermediate gas after removing hydrogen is supplied to the mixer 10 . The mixer 10 further includes a vaporizer 7 via a fifth line L5, an AcH (acetaldehyde) purifier 52 via a sixth line L6, and an EtOH (ethanol) purifier 53 via a sixth line L6. 7 lines L7 are connected to each other.
In the mixer 10, the intermediate gas from which hydrogen has been removed is fed through the ethanol-containing gas supplied through the fifth line L5, the acetaldehyde-containing gas supplied through the sixth line L6, and the seventh line L7. At least one of the second ethanol-containing gas and the ethanol-containing gas derived from the raw material tank independent of the raw material tank 2 is mixed, and the molar ratio of ethanol and acetaldehyde contained in the intermediate gas (hereinafter, “molar ratio P”) is adjusted.

The molar ratio P is preferably 1 to 100, more preferably 1 to 50, still more preferably 1 to 20, particularly preferably 1 to 10, 1 to 5 or 1.5. 1 to 3 is most preferred. If the molar ratio P is within the above range, the yield of butadiene is improved.
Further, the mixer 10 may be provided with an analyzer for analyzing the components contained in the intermediate gas. In this case, based on the results of monitoring the molar ratio P with an analyzer, the ethanol-containing gas mixed with the intermediate gas, the acetaldehyde-containing gas, the ethanol-containing gas derived from the raw material tank independent of the raw material tank 2, and the second ethanol-containing gas can be adjusted. This makes it easier to control the molar ratio P within the above range.
For the spectrometer, for example, a process mass spectrometer or a gas chromatograph can be used.

In the present embodiment, in the mixer 10, the ethanol-rich ethanol-containing gas produced in the vaporizer 7 is directly mixed with the intermediate gas, and the acetaldehyde-containing gas and the second ethanol-containing gas obtained from the refining unit 5, which will be described later, are mixed together. Recycled and mixed with intermediate gas.
Here, although the intermediate gas discharged from the first reactor 3 tends to have a low ethanol concentration, it is mixed with an ethanol-rich ethanol-containing gas, so an extreme drop in concentration can be prevented.
In addition, since the acetaldehyde-containing gas and the second ethanol-containing gas recovered from the refining unit 5 are reused, the molar ratio P is controlled to a relatively high value within the above range while preventing an increase in the production cost of butadiene. it becomes possible to Therefore, the conversion efficiency to butadiene is enhanced, and the yield can be significantly increased.

The temperature controller TC4 heats the intermediate gas.
The temperature at this time is set according to the conversion reaction of ethanol and acetaldehyde to butadiene (type of second catalyst) by the second catalyst, and is not particularly limited, but is preferably 50 to 500° C., preferably 300 to 400° C. °C, more preferably 320 to 370°C. In this case, the conversion of ethanol and acetaldehyde to butadiene can be increased while reducing excessive energy consumption (ie, carbon dioxide emissions).

The conversion of ethanol and acetaldehyde to butadiene in the second reactor 4 is preferably above 30%, more preferably above 40%, and even more preferably above 50%.
Here, the "conversion rate to butadiene" refers to the number of moles of ethanol and acetaldehyde contained in the intermediate gas supplied to the second reactor 4 per unit time in the second reactor 4 (second catalyst). Means the ratio (percentage) 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 second reactor 4 is calculated from the number of moles per unit time of ethanol and acetaldehyde contained in the intermediate gas supplied to the second reactor 4. 2 Calculated by subtracting the number of moles per unit time of ethanol and acetaldehyde contained in the exhaust gas discharged from the reactor 4 (hereinafter also referred to as "crude gas").

The butadiene selectivity in the conversion reaction in the second reactor 4 is preferably over 60%, more preferably over 70%, and even more preferably over 80%.
Here, the "butadiene selectivity" is the ratio of the number of moles per unit time of ethanol and acetaldehyde converted to butadiene to the number of moles per unit time of ethanol and acetaldehyde consumed in the second reactor 4. means (percentage).
Preferably, about 65-80% of the acetaldehyde is converted to butadiene in the second reactor 4 .
By-products that may be contained in the crude product gas discharged from the second reactor 4 include, for example, ethylene, propylene, diethyl ether, ethyl acetate, butanol, hexanol, 1-butene, 2-butene, isobutene, pentene, pentadiene, hexene, hexadiene, acetic acid, butyric acid, crotonic acid, crotonaldehyde, crotyl alcohol, octene, octadiene, hexenoic acid, octenoic acid, 2,4-dimethylfuran, 2-methyl-2-cyclopentene-1 -one, 2,5-diethylphenol, 1,2,3-trimethylindene, 4-hydroxy-4-methyl-2-pentanone, diethylacetal and the like.

The crude product gas discharged from the second reactor 4 is supplied to the refining section 5 via the third line L3.
A temperature control device TC5, a booster 11, a temperature control device TC6, and an inorganic gas separator 12 are arranged in order from the upstream side in the middle of the third line L3.
The temperature controller TC5 cools the crude gas.
The pressure of the crude product gas after cooling is increased by passing through the booster 11 . As a result, the amount of crude product gas that can be processed by the inorganic gas separator 12 at one time can be increased. In addition, the inorganic gas separator 12 can separate hydrogen (inorganic gas) with less entrainment of acetaldehyde and butadiene. At this time, the temperature of the crude product gas rises as the pressure rises.
The booster 11 can have the same configuration as the booster 8 .

The temperature controller TC6 cools the crude gas again.
The crude product gas after cooling passes through the inorganic gas separator 12 . As described above, inorganic gases such as hydrogen and inert gases are mixed in the crude product gas produced in the second reactor 4 , so the inorganic gases are removed by the inorganic gas separator 12 . As a result, it is possible to prevent or suppress the inhibition of the purification of butadiene and the conversion of butadiene into by-products in the purification section 5 .
The concentration of the inorganic gas contained in the crude product gas after passing through the inorganic gas separator 12 is preferably 30% by volume or less, more preferably 20% by volume or less, relative to the entire crude product gas. , more preferably 10% by volume or less, and may be 0% by volume.
The inorganic gas separator 12 can have the same configuration and processing conditions as the hydrogen separator 9 .
The separated inorganic gas may be discarded after being subjected to a predetermined treatment, or the inorganic gas such as hydrogen or nitrogen may be purified and recovered and then reused in other processes.

The refining unit 5 includes a light hydrocarbon separator 51, an AcH purifier 52 connected to the light hydrocarbon separator 51, an EtOH purifier 53 connected to the AcH purifier 52, an EtOH purifier 53 and light carbonization. and a BD extractor 54 connected to the hydrogen separator 51 .
The light hydrocarbon separator 51 is composed of, for example, a distillation column. In the light hydrocarbon separator 51, a liquid containing mainly ethanol and acetaldehyde (hereinafter also referred to as "raw material-containing liquid"), a light hydrocarbon-containing gas, and a gas containing mainly butadiene (butadiene-containing gas) are separated. separated into
Light hydrocarbons include, for example, ethylene, propylene, diethyl ether, ethyl acetate, 1-butene, 2-butene and the like.
The light hydrocarbon-containing gas is withdrawn from the top of the distillation column, subjected to a predetermined treatment, and then discarded. After withdrawing the light hydrocarbon-containing gas, the butadiene-containing gas is withdrawn from the top of the distillation column and fed to the BD extractor 54 . On the other hand, the raw material-containing liquid is withdrawn from the bottom of the distillation column and supplied to the AcH purifier 52 .

The AcH purifier 52 is composed of, for example, a distillation column. In the AcH purifier 52, it is separated into an ethanol-containing liquid and an acetaldehyde-containing gas.
The acetaldehyde-containing gas is withdrawn from the top of the distillation column and supplied to mixer 10 via sixth line L6. On the other hand, the ethanol-containing liquid is withdrawn from the bottom of the distillation column and supplied to the EtOH purifier 53 .
The EtOH purifier 53 is also composed of, for example, a distillation column. In the EtOH purifier 53, the remaining liquid containing water, the second ethanol-containing gas, and the butadiene-containing gas are separated.
The butadiene-containing gas is withdrawn from the top of the distillation column and supplied to the BD extractor 54 . After extracting the butadiene-containing gas, the second ethanol-containing gas is extracted from the top of the distillation column and supplied to the mixer 10 via the seventh line L7. On the other hand, the residual liquid is withdrawn from the bottom of the distillation column, subjected to a predetermined treatment, and then discarded.

The BD extractor 54 is configured by, for example, an extraction tower. The BD extractor 54 extracts butadiene and purifies butadiene.
As the extraction tower, for example, a perforated plate extraction tower, a baffle extraction tower, a dam type (WINTRAY) extraction tower, or the like can be used.

Next, a method for producing butadiene using such a production apparatus 1, that is, a method for producing butadiene according to the present embodiment will be described.
The method for producing butadiene mainly comprises a first reactor 3 that converts (converts) ethanol into acetaldehyde, and a hydrogen separator (inorganic gas separation This is a method of producing butadiene by passing a raw material gas through a second reactor 4 that converts (converts) ethanol and acetaldehyde into butadiene, in that order.
As shown in FIG. 2, the first reactor 3 and the second reactor 4 are connected in parallel with each other, and a plurality (in this embodiment, two) filled with a catalyst (first catalyst or second catalyst). ) are equipped with reaction tubes Ra and Rb.

The number of reaction tubes to be installed may be two or more, but may be 3 to 20 (preferably 5 to 15). Moreover, a plurality of reaction tubes may be housed in an outer container to constitute each of the reactors 3 and 4 .
In this embodiment, a reaction process is performed in which a raw material gas is passed through some of the reaction tubes Ra and Rb at a temperature of 300 to 420° C., and a catalyst is supplied to the remaining reaction tubes Ra and Rb. It is alternated with a regeneration process in which a regenerating regeneration gas is passed through at a temperature of 420-550°C. That is, when the reaction process is performed first in the reaction tube Ra, then the regeneration process is performed in the reaction tube Ra, while when the regeneration process is first performed in the reaction tube Rb, then the reaction process is performed in the reaction tube Rb. is performed, and these processes are repeated alternately.

As the regeneration gas, an oxygen-containing gas having an oxygen concentration of 0.01 to 100% by volume is preferably used. By using such an oxygen-containing gas, even if carbon components, sulfur components, nitrogen components, etc. adhere (precipitate) on the catalyst and the catalytic activity is lowered, these components react with oxygen. . As a result, these components are removed in the form of corresponding oxides, thereby restoring catalytic activity (ie, regenerating the catalyst).
The oxygen concentration of the oxygen-containing gas is preferably 1 to 100% by volume, more preferably 10 to 70% by volume, even more preferably 20 to 50% by volume. If the oxygen concentration of the oxygen-containing gas is within the above range, the catalytic activity is easily recovered in a short time, the yield of 1,3-butadiene is improved, and the oxygen concentration is prevented from becoming too high. Contributes to reducing the possibility of explosion due to heat generation.

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.
The oxygen-containing gas is preferably a gas obtained by diluting oxygen gas with a diluent gas from the viewpoint of facilitating adjustment of the oxygen concentration to a desired concentration. From the viewpoint of availability, the oxygen-containing gas is preferably air.
In the present invention, the contact frequency of the raw material gas and the regeneration gas with respect to the catalyst, represented by the following formula (1), is set to 500 to 50,000.
Contact frequency = (flow rate of raw material gas and regeneration gas [kg/hr] x pressure in reaction tubes Ra and Rb [MPaA])/(area occupied by the catalyst in the cross section at the center of the reaction tubes Ra and Rb in the longitudinal direction [ m ² ]×the outer diameter of reaction tubes Ra and Rb [m]) (1)

According to such a configuration, the energy input to the reaction process and the regeneration process can be reduced without reducing the yield of butadiene. In addition, since there is no need to dispose a booster for boosting the pressure of the raw material gas and the regeneration gas supplied to the reaction tubes Ra and Rb immediately before the reaction tubes Ra and Rb, the energy required for the booster can also be reduced. . As a result, the amount of carbon dioxide emitted per butadiene production can be reduced.
The contact frequency represented by the above formula (1) may be from 500 to 50000, preferably from 500 to 25000, more preferably from 500 to 10000, and even more preferably from 500 to 5000. . In this case, less energy can be put into the reaction process and the regeneration process.

The flow rates of the raw material gas and the regeneration gas are not particularly limited, but are preferably 1000 to 100000 kg/hr, more preferably 5000 to 50000 kg/hr.
The pressure inside the reaction tubes Ra and Rb is also not particularly limited, but is preferably 0.02 to 5 MPaA, more preferably 0.05 to 2 MPaA.
The area occupied by the catalyst in the cross section at the center in the longitudinal direction (vertical direction) of the reaction tubes Ra and Rb (hereinafter also referred to as “cross-sectional area of the catalyst layer”) is preferably 0.1 to 10 m ² . , 0.5 to 5 m ² .
Furthermore, the outer diameter of the reaction tubes Ra and Rb is preferably 0.1 to 5 m, more preferably 0.5 to 1 m.
By setting the cross-sectional area of the catalyst layer and the outer diameter of the reaction tubes Ra and Rb within the above ranges, it is possible to prevent the tube thickness (thickness) of the reaction tubes Ra and Rb from increasing. In this case, for example, when heating the raw material gas and the regeneration gas from the outside of the reaction tubes Ra and Rb, the heat is more rapidly transferred to the inside of the reaction tubes Ra and Rb.

In this embodiment, it is preferable to have a replacement process of passing an inert gas through the reaction tubes Ra and Rb between the reaction process and the regeneration process. By providing a replacement process, it is possible to sufficiently eliminate the possibility of contact between the hydrogen produced as a by-product in the reaction process and the oxygen-containing gas used in the regeneration process, thereby more reliably preventing the risk of explosion. can be done. Examples of inert gases include rare gases such as nitrogen gas and argon gas.
The rate of temperature increase from the reaction process to the regeneration process and the rate of temperature decrease from the regeneration process to the reaction process are: Reaction process time > (Temperature difference between reaction process and regeneration process) ÷ (Temperature increase rate above) + (Regeneration process and temperature decrease rate) It is preferable to make adjustments so as to satisfy the following relationship: temperature difference from the reaction process)/(the rate of temperature drop)+(replacement process time)+(regeneration process time). As a result, it is possible to extend the life of the catalyst while maintaining the yield of butadiene.

When the time on the left side (reaction process time) is X [time] and the time on the right side (time other than the reaction process time including the regeneration process) is Y [time], XY is 0.1 hours. It is preferably 0.5 hours or longer, more preferably 1 hour or longer. XY is usually 10 hours or less. In this case, the time during which the catalyst cannot be used in the reaction process can be shortened, and the yield of butadiene can be further increased.
Although the specific value of the heating rate is not particularly limited, it is preferably 0.05 to 20°C/min, more preferably 0.1 to 10°C/min.
On the other hand, the specific value of the temperature drop rate is also not particularly limited, but is preferably 0.05 to 20°C/min, more preferably 0.1 to 10°C/min.

Moreover, the manufacturing apparatus 1 preferably includes a heating mechanism for heating the raw material gas in the reaction process.
3 to 5 are schematic diagrams showing the configuration of the heating mechanism that heats the raw material gas.
The heating mechanism 20 shown in FIG. It has a tank 22 , a heat exchanger 23 and an electric heater 24 .
The heat medium transfer line 21 has a pipe 29 provided in contact with the outer surfaces of the reaction tubes Ra and Rb. The heat medium heated by the heat exchanger (economizer) 23 and the electric heater 24 can heat the raw material gas in the reaction tubes Ra and Rb through the reaction tubes Ra and Rb when passing through the piping 29. can.

The heat exchanger 23 can be applied to, for example, the temperature control device TC2, the temperature control device TC3, the temperature control device TC5, the temperature control device TC6, etc. The piping can be bent so as to be close to the piping that constitutes the heat medium transfer line 21 . According to such a configuration, the high-temperature raw material gas (or intermediate gas) after passing through the first reactor 3 and the second reactor 4 is used to supply the first reactor 3 and the second reactor 4 Since the previous heat medium is heated by heat exchange, the heat can be effectively utilized. Therefore, additional energy can be reduced, and carbon dioxide generated during energy generation can be reduced.
Such heat exchangers 23 are, for example, jacket heat exchangers, immersion coil heat exchangers, double tube heat exchangers, shell and tube heat exchangers, plate heat exchangers, spiral heat exchangers. It can be configured as a vessel or the like.
In addition, in the heating mechanism 20, either one of the heat exchanger 23 and the electric heater 24 may be omitted.

Further, the electric heater 24 can be configured to directly heat the reaction tubes Ra and Rb instead of heating the heat medium in the heat medium transfer line 21 .
Furthermore, the heating mechanism 20 may include a microwave irradiator instead of at least one of the heat exchanger 23 and the electric heater 24, or together with the heat exchanger 23 and the electric heater 24.
If a microwave irradiator is used, the reaction tubes Ra, Rb and the packed catalyst can be heated to the desired temperature in a relatively short period of time. Moreover, it is easy to uniformly heat not only the vicinity of the surface of the catalyst but also the central portion. Furthermore, it is easy to precisely control the heating temperature of the catalyst (raw material gas). Therefore, the production efficiency of butadiene can be further enhanced.
Alternatively, the heating medium may be heated by a microwave irradiator.

Microwave means electromagnetic waves with a frequency of 300 MHz to 300 GHz, ultra high frequency (UHF) with a frequency of 300 to 3000 MHz, centimeter wave (SHF) with a frequency of 3 to 30 GHz, millimeter wave (EHF) with a frequency of 30 to 300 GHz, frequency 300 It is classified as submillimeter wave (SHF) of ~3000 GHz. Among them, ultrahigh frequency (UHF) is preferable as the microwave. By using ultrahigh frequency (UHF), the catalyst or reaction tubes Ra, Rb can be heated to the desired temperature in a shorter time.
In addition, when irradiating with microwaves, appropriate countermeasures against leakage of radio waves complying with the Radio Law are taken.

Further, the microwave irradiation may be performed continuously or intermittently (in pulses).
The present inventors have found that continuous microwave irradiation further increases the yield of butadiene and the regeneration efficiency of the catalyst. Although the reason is not necessarily clear, it is considered that the gas and the catalyst supplied into the reaction tubes Ra and Rb are activated by the continuously irradiated microwaves.
On the other hand, when the microwave irradiation is performed intermittently, the microwave irradiation should be performed at a predetermined timing so as to compensate only for the energy required for the endothermic reaction during regeneration of the butadiene yield and the catalyst. Therefore, energy efficiency can be improved.

In the heating mechanism 20 shown in FIG. 4, the heat medium transfer line 21 includes a first branch line 21a and a second branch line 21b that branches off from the first branch line 21a and then merges with the first branch line 21a.
In the configuration example shown in FIG. 4, the first branch line 21a has a pipe 29 provided in contact with the outer surfaces of the reaction tubes Ra and Rb, and the second branch line 21b contacts the inner surfaces of the reaction tubes Ra and Rb. It has a pipe 28 that is provided at the bottom. The piping 28 is also in direct contact with the catalyst by being provided inside the reaction tubes Ra and Rb. According to such a configuration, the heating efficiency of the catalyst (raw material gas) can be further enhanced.

In the heating mechanism 20 shown in FIG. 5, the heat medium transfer line 21 includes first branch lines 21a and 21c, and a second branch line 21b that branches off from the first branch lines 21a and 21c and then joins again. .
In the configuration example shown in FIG. 5, the first branch lines 21a and 21c have pipes 29 provided in contact with the outer surfaces of the reaction tubes Ra and Rb, respectively, and the second branch line 21b is the center of the reaction tubes Ra and Rb. It has a pipe 28 running along the axis. The pipes 28 are provided along the central axes of the reaction tubes Ra and Rb so as to penetrate the catalyst layers and directly contact the catalysts.

In addition, the transfer direction of the heat medium in the first branch lines 21a and 21c with respect to the reaction tubes Ra and Rb is the direction from the top to the bottom in the longitudinal direction (vertical direction), and the heat medium in the second branch line 21b. is the opposite direction, that is, from the bottom to the top of the longitudinal direction (vertical direction).
In this manner, by allowing the heat medium to pass through the reaction tubes Ra and Rb in two different directions, it becomes possible to heat the catalyst (raw material gas) more efficiently. In particular, by allowing the heat medium to pass along the central axes of the reaction tubes Ra and Rb, it is possible to prevent the temperature of the catalyst from lowering due to the endothermic reaction. Therefore, it is possible to further reduce the amount of carbon dioxide emitted per production amount of butadiene by reusing thermal energy without lowering the butadiene conversion reaction.

When each of the reactors 3 and 4 has a configuration in which a plurality of reaction tubes Ra and Rb are accommodated in the outer container, the first branch lines 21a and 21c and the second branch line 21b are respectively connected to the reaction tubes Ra and Rb. , the outside of the reaction tubes Ra and Rb, the inside of the reactor (outer container), and the outside of the reactor (outer container). This configuration can be changed as appropriate depending on the combination of the catalyst, reaction tube, and reactor used, making it possible to keep the catalytic reaction state optimal and constant and to minimize thermal energy in the production of butadiene.

<Second embodiment>
Next, a second embodiment of the method for producing butadiene of the present invention will be described.
FIG. 6 is a schematic diagram showing part of a production apparatus used in the second embodiment of the method for producing butadiene of the present invention.
In the following, the manufacturing apparatus used in the second embodiment will be described with a focus on differences from the manufacturing apparatus used in the first embodiment, and the description of the same items will be omitted.
The manufacturing apparatus 1 shown in FIG. 6 is the same as the manufacturing apparatus 1 of the first embodiment except for the configuration of the heating mechanism.

In the heating mechanism of the second embodiment, the heat medium is the raw material gas after passing through the first reactor 3 (reaction tubes Ra, Rb), and the heat medium transfer line is a line for transferring the raw material gas (raw material gas transfer line) L2.
The heat exchanger (economizer) 13 is configured to exchange heat between the source gas after passing through the first reactor 3 and the source gas before passing through the first reactor 3. . A pressure booster 8 is provided between the first reactor 3 and the heat exchanger 13 in the middle of the second line L2.
In addition, when a raw material gas supply line independent from the raw material tank 2 is installed together, the heat exchanger (economizer) 13 may be configured to perform heat exchange with the independent raw material gas. .

According to such a configuration, one heat exchanger 13 can exhibit the functions of the temperature control device TC1 and the temperature control device TC3 in FIG.
Therefore, the configuration of the manufacturing apparatus 1 can be simplified, and the heat of the first reactor 3 and the booster 8 can be efficiently used. Therefore, the amount of carbon dioxide emitted per butadiene production can be reduced.
Although the configuration around the first reactor 3 is shown in FIG. 6, the same configuration can be adopted around the second reactor 4 as well.

<Third Embodiment>
Next, a third embodiment of the method for producing butadiene of the present invention will be described.
FIG. 7 is a schematic diagram showing part of a production apparatus used in the third embodiment of the method for producing butadiene of the present invention.
In the following, the manufacturing apparatus used in the third embodiment will be described with a focus on the differences from the manufacturing apparatuses used in the first and second embodiments, and the description of the same items will be omitted.
The manufacturing apparatus 1 shown in FIG. 7 is the same as the manufacturing apparatus 1 of the first embodiment except for the configuration of the heating mechanism.

In the manufacturing apparatus 1 of the third embodiment, each of the temperature control devices TC1 to TC3 is composed of a heat exchanger.
A heating mechanism 30 is configured by connecting the temperature control device TC1 and the temperature control device TC3 with a heat medium transfer line 31 for transferring (circulating) a heat medium therebetween. A heating mechanism 40 is configured by connecting the temperature control device TC1 and the temperature control device TC2 with a heat medium transfer line 41 that transfers (circulates) a heat medium therebetween.
With such a configuration, the configuration of the manufacturing apparatus 1 can be simplified, and the heat of the first reactor 3 and the booster 8 can be efficiently used. Therefore, the amount of carbon dioxide emitted per butadiene production can be reduced.
Although the configuration around the first reactor 3 is shown in FIG. 7, the same configuration can be adopted around the second reactor 4 as well.

<Fourth Embodiment>
Next, a fourth embodiment of the method for producing butadiene of the present invention will be described.
FIG. 8 is a schematic diagram showing the configuration of the second heating mechanism that heats the regeneration gas.
Hereinafter, the manufacturing apparatus of the fourth embodiment will be described with a focus on the differences from the manufacturing apparatuses of the first to third embodiments, and the description of the same items will be omitted.
The manufacturing apparatus 1 shown in FIG. 8 further includes a second heating mechanism for heating the regeneration gas in the regeneration process, and otherwise is the same as the manufacturing apparatus 1 of the first embodiment.

The second heating mechanism 90 shown in FIG. 8 is provided separately from the heating mechanism 20, and includes a second heat medium transfer line 91 capable of transferring a heat medium for regeneration (second heat medium) that supplies heat to the regeneration gas. , a regenerating heat medium tank 92 provided in the middle of the second heat medium transfer line 91, a second heat exchanger 93 and a second electric heater 94.
The second heat medium transfer line 91 has a pipe 99 provided in contact with the outer surfaces of the reaction tubes Ra and Rb. The heat medium for regeneration heated by the second heat exchanger (economizer) 93 and the second electric heater 94 passes through the reaction tubes Ra and Rb when passing through the pipe 99, and the regeneration in the reaction tubes Ra and Rb. Gas can be heated.

The second heat exchanger 93 can be applied to, for example, the temperature control device TC2, the temperature control device TC3, the temperature control device TC5, the temperature control device TC6, etc., and a part of the pipes forming the second line L2 is bent. and close to the piping that constitutes the second heat medium transfer line 91 . According to such a configuration, the high-temperature raw material gas (or intermediate gas) after passing through the first reactor 3 and the second reactor 4 is used to supply the first reactor 3 and the second reactor 4 Since the previous heat medium is heated by heat exchange, the heat can be effectively utilized. Therefore, additional energy can be reduced, and carbon dioxide generated during energy generation can be reduced.
Such a second heat exchanger 93 can have the same configuration as the heat exchanger 23 .

According to such a configuration, the temperature of the heat medium for reaction and the temperature of the heat medium for regeneration do not need to fluctuate greatly, and can be maintained at a predetermined temperature. For this reason, it is possible to reduce the energy to be input in the production of butadiene, and thus to reduce the amount of carbon dioxide emitted per production amount of butadiene.
In addition, in the second heating mechanism 90, either one of the second heat exchanger 93 and the second electric heater 94 may be omitted.
Further, the second electric heater 94 can be configured to directly heat the reaction tubes Ra and Rb instead of heating the regeneration heat medium in the second heat medium transfer line 91 .

Furthermore, the second heating mechanism 90 replaces at least one of the second heat exchanger 93 and the second electric heater 94, or together with the second heat exchanger 93 and the second electric heater 94. A similar second microwave irradiator may be provided.
By using the second microwave irradiator, the reaction tubes Ra, Rb and the packed catalyst can be heated to the target temperature in a relatively short time. Moreover, it is easy to uniformly heat not only the vicinity of the surface of the catalyst but also the central portion. Furthermore, it is easy to precisely control the heating temperature of the catalyst (regeneration gas). Therefore, the production efficiency of butadiene can be further improved.
Note that the second microwave irradiator may heat the regeneration heat medium.

Instead of the second heating mechanism 90, a preheated regeneration gas supply mechanism may be provided for supplying preheated regeneration gas to the reaction tubes Ra and Rb in the regeneration process.
In this case, there is an advantage that it is not necessary to prepare many types of heat medium. In addition, the energy for heating each heat medium is reduced, and the amount of carbon dioxide emissions per production amount of butadiene can be further reduced.

<Fifth Embodiment>
Next, a fifth embodiment of the method for producing butadiene of the present invention will be described.
In the following, the manufacturing apparatus used in the fifth embodiment will be described with a focus on differences from the manufacturing apparatuses in the first to fourth embodiments, and the description of the same items will be omitted.
The production apparatus 1 of the fifth embodiment further includes a third heating mechanism for heating the catalyst after the reaction process is finished and before the regeneration process is started. be.

The third heating mechanism is provided separately from the heating mechanism 20 and the second heating mechanism 90, and is a third heating medium transfer line capable of transferring a heating medium (third heating medium) for supplying heat to the catalyst. and a heating medium tank for raising temperature, a third heat exchanger, and a third electric heater provided in the middle of the third heating medium transfer line, and each part is provided in the same manner as the heating mechanism 20 and the second heating mechanism 90 Can be configured.
According to this configuration, since the heating medium is used in addition to the heating medium for reaction and the heating medium for regeneration, the temperature of the heating medium for reaction and the temperature of the heating medium for regeneration do not need to fluctuate further. , should be maintained at a predetermined temperature. Therefore, it is possible to further reduce the energy input in the production of butadiene, and thus the amount of carbon dioxide emitted per butadiene production can be sufficiently reduced.
In the third heating mechanism, either one of the third heat exchanger and the third electric heater may be omitted.
Further, the third electric heater can be configured to directly heat the reaction tubes Ra and Rb instead of heating the heating medium in the third heating medium transfer line.

In addition, the third heating mechanism replaces or together with the third heat exchanger and/or the third electric heater includes a third microwave similar to the microwave irradiator described above. A wave irradiator may be provided.
By using the third microwave irradiator, the reaction tubes Ra, Rb and the packed catalyst can be heated to the desired temperature in a relatively short time. Moreover, it is easy to uniformly heat not only the vicinity of the surface of the catalyst but also the central portion. Furthermore, it is easy to precisely control the heating temperature of the catalyst. Therefore, the production efficiency of butadiene can be further improved.
It should be noted that the third microwave irradiator may be used to heat the heating medium for increasing the temperature.

<Sixth embodiment>
Next, a sixth embodiment of the method for producing butadiene of the present invention will be described.
In the following, the manufacturing apparatus used in the sixth embodiment will be described with a focus on the differences from the manufacturing apparatuses in the first to fifth embodiments, and the description of the same items will be omitted.
The production apparatus 1 of the sixth embodiment further includes a cooling mechanism for cooling the catalyst after the regeneration process is finished and before the reaction process is started, and otherwise is the same as the production apparatus 1 of the fifth embodiment.

This cooling mechanism includes a refrigerant transfer line capable of transferring a temperature-lowering heat medium (refrigerant) for removing heat from the catalyst, a refrigerant tank, a fourth heat exchanger, and a cooler provided in the middle of the refrigerant transfer line. , each part can be configured in the same manner as the heating mechanism 20 and the second heating mechanism 90 .
According to such a configuration, since the refrigerant is used in addition to the heat medium for reaction and the heat medium for regeneration, there is no need to greatly fluctuate the temperature of the heat medium for reaction and the temperature of the heat medium for regeneration. should be maintained at Therefore, it is possible to further reduce the energy input in the production of butadiene, and thus the amount of carbon dioxide emitted per butadiene production can be sufficiently reduced.
In addition, in the cooling mechanism, either one of the fourth heat exchanger and the cooler may be omitted.

In the manufacturing apparatus 1 of the sixth embodiment, the reaction process, the temperature increasing process from the reaction process to the regeneration process, the regeneration process, and the temperature decreasing process from the regeneration process to the reaction process are repeated in this order.
In this case, preheated gas may be used to adjust the temperature inside the reaction tubes Ra and Rb. In this case, it is preferable to use gases with different gas compositions for the four processes.

The raw material gas itself is preferably used as the first gas in the reaction process, and the regeneration gas itself is preferably used as the third gas in the regeneration process. On the other hand, nitrogen gas is preferably used as the second gas in the temperature raising process, and a rare gas is preferably used as the fourth gas in the temperature lowering process.
Moreover, in this case, it is preferable to perform heat exchange between the first gas and the third gas, and to perform heat exchange between the second gas and the fourth gas.
It eliminates the need to heat and lower the temperature of the heat medium, and heat exchange can efficiently reduce input energy. Therefore, the amount of carbon dioxide emitted per butadiene production can be sufficiently reduced.

Although the method for producing butadiene of the present invention has been described above, the present invention is not limited thereto.
For example, the method for producing butadiene of the present invention may have steps for any other purpose with respect to the above embodiment, and may be replaced with any steps that exhibit similar functions.
Also, any configuration of the first to sixth embodiments may be combined.

DESCRIPTION OF SYMBOLS 1... Manufacturing apparatus 2... Raw material tank 3... 1st reactor 4... 2nd reactor 5... Purification part 51... Light hydrocarbon separator 52... AcH refiner 53... EtOH refiner 54... BD extractor 6... Inert Gas tank 7 Vaporizer 8 Booster 9 Hydrogen separator 10 Mixer 11 Booster 12 Inorganic gas separator 13 Heat exchanger 20 Heating mechanism 21 Heat medium transfer line 21a First branch line 21b Second branch line 21c First branch line 22 Heat medium tank 23 Heat exchanger 24 Electric heater 28 Pipe 29 Pipe 30 Heating mechanism 31 Heat medium transfer line 40 Heating mechanism 41 Heat medium transfer Line 90 Second heating mechanism 91 Heat medium transfer line 92 Heat medium tank for regeneration 93 Heat exchanger 94 Electric heater 99 Piping L1 First line L2 Second line L3 Third line L4 Third line Line 4 L5... Fifth line L6... Sixth line L7... Seventh line TC1... Temperature controller TC2... Temperature controller TC3... Temperature controller TC4... Temperature controller TC5... Temperature controller TC6... Temperature controller

Claims (13)

The raw material gas passes through the first reactor that converts ethanol to acetaldehyde, the inorganic gas separator that separates the inorganic gas by-produced in the first reactor, and the second reactor that converts ethanol and acetaldehyde to butadiene, in that order. A method for producing butadiene by allowing
each reactor comprises a plurality of reaction tubes connected in parallel and filled with a catalyst;
A reaction process in which the raw material gas is passed through some of the reaction tubes out of the plurality of reaction tubes at a temperature of 300 to 420 ° C., and a regeneration gas for regenerating the catalyst is supplied to the remaining reaction tubes at 420 to 550 ° C. in alternating with the regeneration process passing through at a temperature of
A method for producing butadiene, wherein the contact frequency represented by the following formula (1) of the raw material gas and the regeneration gas with respect to the catalyst is set to 500 to 50,000.
Contact frequency = (flow rate of raw material gas and regeneration gas [kg/hr] x pressure in reaction tube [MPaA])/(area occupied by catalyst in cross section at the center in the longitudinal direction of reaction tube [m ² ] x reaction tube Outer diameter [m]) (1) The method for producing butadiene according to claim 1, wherein the conditions for passing the raw material gas through the inorganic gas separator are a temperature of 3 to 15°C and a pressure of 0.5 to 5 MPaG. Between the reaction process and the regeneration process, a replacement process of passing an inert gas through the reaction tube,
Time of the reaction process>(temperature difference between the reaction process and the regeneration process)/(heating rate from the reaction process to the regeneration process) + (temperature difference between the regeneration process and the reaction process)/( 2. The rate of temperature increase and the rate of temperature decrease are adjusted so as to satisfy the following relationship: rate of temperature drop from the regeneration process to the reaction process)+(time of the replacement process)+(time of the regeneration process). 3. The method for producing butadiene according to 2 above. Furthermore, in the reaction process, a heating mechanism for heating the raw material gas is provided,
4. Any one of claims 1 to 3, wherein the heating mechanism includes at least one selected from a heat exchanger, an electric heater, and a microwave irradiator for exchanging heat with the heat medium transferred in the heat medium transfer line. 1. The method for producing butadiene according to claim 1. The heat medium transfer line includes a first branch line and a second branch line that rejoins after branching off from the first branch line,
5. The method for producing butadiene according to claim 4, wherein the direction of transfer of the heat medium in the first branch line is opposite to the direction of transfer of the heat medium in the second branch line with respect to the reaction tube. The first branch line and the second branch line are provided in at least one selected from the inside of the reaction tube, the outside of the reaction tube and the inside of the reactor, and the outside of the reactor, respectively. Item 6. A method for producing butadiene according to item 5. The heat medium is the source gas after passing through the reaction tube,
The heat medium transfer line also functions as a raw material gas transfer line for transferring the raw material gas, and the heat exchanger connects the raw material gas after passing through the reaction tube and the raw material gas before passing through the reaction tube. 5. The method for producing butadiene according to claim 4, wherein heat is exchanged with the raw material gas. The method for producing butadiene according to any one of claims 4 to 7, comprising a booster for increasing the pressure of the raw material gas on the downstream side of the reaction tube. Furthermore, in the regeneration process, a second heating mechanism for heating the regeneration gas is provided,
The second heating mechanism is provided separately from the heating mechanism, and is a second heat exchanger and a second electric heater that exchange heat with the second heat medium transferred in the second heat medium transfer line. and a second microwave irradiator. The method for producing butadiene according to any one of claims 4 to 8. further comprising a third heating mechanism for heating the catalyst after the reaction process is finished and before the regeneration process is started,
The third heating mechanism is provided separately from the heating mechanism and the second heating mechanism, and performs heat exchange with a third heat medium transferred in a third heat medium transfer line. 10. The method for producing butadiene according to claim 9, comprising at least one selected from a vessel, a third electric heater and a third microwave irradiator. Furthermore, a cooling mechanism for cooling the catalyst after the regeneration process is completed and before the reaction process is started,
11. The cooling mechanism according to any one of claims 1 to 10, comprising at least one selected from a fourth heat exchanger and a cooler that exchange heat with the refrigerant transferred in the refrigerant transfer line. butadiene production method. The method for producing butadiene according to any one of claims 4 to 8, further comprising a preheated regeneration gas supply mechanism for supplying the preheated regeneration gas to the reaction tube in the regeneration process. preheated gas is used to adjust the temperature in the reaction tube;
The gases are a first gas used in the reaction process, a second gas used in a temperature raising process from the reaction process to the regeneration process, and a second gas used in the regeneration process, which are different in gas composition from each other. a third gas and a fourth gas used in a temperature-lowering process from the regeneration process to the reaction process;
The butadiene according to any one of claims 1 to 3, wherein heat exchange is performed between the first gas and the third gas, and heat exchange is performed between the second gas and the fourth gas. manufacturing method.

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