JP7546245B2 - Butadiene production method and butadiene production apparatus - Google Patents

Description

The present invention relates to a method for producing butadiene and an apparatus for producing butadiene.

Conventionally, 1,3-butadiene (hereinafter also abbreviated as "butadiene") has been used as a monomer as a raw material for synthetic rubbers such as butadiene rubber (BR) and styrene-butadiene rubber (SBR), and is mainly obtained as a by-product when naphtha is thermally decomposed by an ethylene cracker (naphtha cracker) to produce ethylene and propylene.
However, in recent years, the amount of butadiene produced has been decreasing due to the shift to light feed materials.
Therefore, as an alternative raw material to petroleum, a process of fermenting biomass (corn or sugarcane) and producing butadiene via butanediol, butanol, butene or ethanol is being researched.

For example, Patent Document 1 describes "a method for producing 1,3-butadiene, characterized in that a raw material containing ethanol is brought into contact with a catalyst, thereby making the proportion of 1,3-butadiene in a C4 fraction consisting of butanes, butenes, and butadienes in the product 98 mol % or more" ([Claim 1]), and also describes a catalyst containing elements of Groups 4 and 5 of the Periodic Table as the catalyst ([Claim 4]).

International Publication No. 2016/125578

The inventors have studied the butadiene production method described in Patent Document 1 and found that the yield of butadiene is poor.

The present invention aims to provide a butadiene production method and butadiene production apparatus that can improve the yield of butadiene.

As a result of intensive research to achieve the above object, the present inventors have found that the yield of butadiene can be improved by contacting a raw material, ethanol or a mixture of ethanol and acetaldehyde, with a solid catalyst comprising at least one metal selected from the group consisting of metals belonging to Groups 11, 12, and 13 supported on a carrier, and a solid catalyst comprising at least one metal selected from the group consisting of metals belonging to Groups 3, 4, and 5 supported on a carrier, in that order, and have thus completed the present invention.
That is, the present inventors have found that the above problems can be solved by the following configuration.

[1] A method for producing butadiene by obtaining butadiene from ethanol or a mixture of ethanol and acetaldehyde, comprising the steps of:
A method for producing butadiene, comprising contacting ethanol or a mixture of ethanol and acetaldehyde with a solid catalyst A comprising at least one metal (A) selected from the group consisting of metals belonging to Groups 11, 12, and 13 supported on a carrier, and a solid catalyst B comprising at least one metal (B) selected from the group consisting of metals belonging to Groups 3, 4, and 5 supported on a carrier, in that order, to obtain butadiene.
[2] The method for producing butadiene according to [1], wherein the temperature when ethanol or a mixture of ethanol and acetaldehyde is brought into contact with the solid catalyst A is 250 to 400°C, and the temperature when it is brought into contact with the solid catalyst B is 350 to 500°C.
[3] The method for producing butadiene according to [1] or [2], wherein the temperature when the ethanol or the mixture of ethanol and acetaldehyde is contacted with the solid catalyst B is higher than 400° C. and not higher than 500° C.
[4] The metal (A) is a metal belonging to Group 11,
The method for producing butadiene according to any one of [1] to [3], wherein the metal (B) is at least one metal selected from the group consisting of metals belonging to Group 3 and Group 4.
[5] The metal (A) is silver,
The method for producing butadiene according to any one of [1] to [4], wherein the metal (B) is at least one selected from the group consisting of hafnium, zirconium, and scandium.
[6] The method for producing butadiene according to any one of [1] to [5], wherein the supports contained in the solid catalyst A and the solid catalyst B are both silica.
[7] The content of the metal (A) is 0.1 to 50 mass% based on the mass of the support contained in the solid catalyst A,
The method for producing butadiene according to any one of [1] to [6], wherein the content of the metal (B) is 0.1 to 50 mass% relative to the mass of the support contained in the solid catalyst B.
[8] An apparatus for producing butadiene from ethanol or a mixture of ethanol and acetaldehyde, comprising:
The reactor A includes a reactor B connected to the reactor A,
The reactor A is a reactor packed with a solid catalyst A comprising at least one metal (A) selected from the group consisting of metals belonging to Groups 11, 12, and 13 supported on a support,
The reactor B is a reactor packed with a solid catalyst B in which at least one metal (B) selected from the group consisting of metals belonging to Groups 3, 4, and 5 is supported on a support,
An apparatus for producing butadiene, wherein ethanol or a mixture of ethanol and acetaldehyde is passed through the reactor A and then the reactor B.

The present invention provides a butadiene production method and butadiene production apparatus that can improve the butadiene yield.

FIG. 1 is a schematic diagram showing an example of an embodiment of the butadiene production apparatus of the present invention.

The present invention will be described in detail below.
The following description of the components may be based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.
In this specification, a numerical range expressed using "to" means a range that includes the numerical values before and after "to" as the lower and upper limits.
In this specification, "butadiene" refers to "1,3-butadiene".
In the present specification, each component may be used alone or in combination of two or more substances corresponding to each component. When two or more substances are used in combination for each component, the content of the component refers to the total content of the substances used in combination, unless otherwise specified.

[Production method of butadiene]
The butadiene production method of the present invention (hereinafter also abbreviated as "the production method of the present invention") is a butadiene production method in which butadiene is obtained from ethanol or a mixture of ethanol and acetaldehyde (hereinafter also abbreviated as "raw material").
The production method of the present invention is a method for obtaining butadiene by contacting a raw material with a solid catalyst A comprising at least one metal (A) selected from the group consisting of metals belonging to Groups 11, 12, and 13 supported on a carrier (hereinafter also abbreviated as "carrier A") and a solid catalyst B comprising at least one metal (B) selected from the group consisting of metals belonging to Groups 3, 4, and 5 supported on a carrier (hereinafter also abbreviated as "carrier B") in this order.
In the present invention, the metal (A) and the metal (B) may be present on the carrier A and the carrier B, respectively, as a metal or as a compound such as a metal oxide.

In the present invention, as described above, the yield of butadiene is improved by contacting the raw material with the solid catalyst A and then the solid catalyst B in this order.
Although the details of this are not clear, the present inventors speculate as follows.
That is, as shown in Comparative Examples 1-1 to 1-4 described later, when a metal not belonging to Groups 3 to 5 is supported on a carrier as the solid catalyst B, or when the order of the solid catalysts with which the raw materials are contacted is reversed as shown in Comparative Example 1-5 described later, a dehydration reaction, which is a side reaction, occurs, and it is considered that the yield of butadiene is low.
Therefore, in the present invention, it is considered that by contacting the raw material with the predetermined solid catalyst A and then the solid catalyst B in this order, the progress of the dehydration reaction, which is a side reaction, is suppressed and the selectivity of butadiene is improved, thereby improving the yield of butadiene.

[Solid catalyst A]
The solid catalyst A used in the production method of the present invention is a solid catalyst comprising at least one metal (A) selected from the group consisting of metals belonging to Groups 11, 12 and 13 supported on a support A.

<Carrier A>
The carrier A used in the solid catalyst A is not particularly limited as long as it can support the metal (A) described below, and specific examples thereof include silica, alumina, magnesia, and the like.

In the present invention, it is preferable that carrier A is silica, because this increases the ethanol conversion rate and the butadiene selectivity, thereby improving the butadiene yield.

In the present invention, because the selectivity of butadiene is further increased and the yield of butadiene is further improved, it is preferable to use silica having an average pore diameter in the range of 3 to 15 nm as the carrier A, and it is more preferable to use silica having an average pore diameter in the range of more than 3 nm and not more than 10 nm.
The term "average pore diameter" as used herein refers to the pore diameter showing the peak value of the pore diameter distribution curve obtained from the nitrogen adsorption isotherm by the BJH method or the DFT method.

<Metal (A)>
The metal (A) contained in the solid catalyst A is at least one metal selected from the group consisting of metals belonging to Groups 11, 12 and 13.
Specific examples of metals belonging to Group 11 include copper (Cu), silver (Ag), and Au (gold).
Specific examples of metals belonging to Group 12 include zinc (Zn), cadmium (Cd), and mercury (Hg).
Specific examples of metals belonging to Group 13 include aluminum (Al), gallium (Ga), and indium (In).

Here, the raw material of the metal belonging to Group 11 is not particularly limited, but examples thereof include nitrates and acetates of metals selected from Group 11. Specific examples thereof include Ag(NO ₃ ), CH ₃ COOAg, etc.
The raw material of the metal belonging to Group 12 is not particularly limited, but examples thereof include nitrates, acetates, and hydrates thereof of metals selected from Group _12. Specific examples include Zn( _NO3 ) ₂ , Zn( _NO3 ) _2.6H2O , and Zn( _OCOCH3 ) ₂ .
The raw material of the metal belonging to Group 13 is not particularly limited, but examples thereof include nitrates, oxynitrates, acetates, oxyacetates, and hydrates thereof of metals selected from Group 13. Specific examples thereof include aluminum nitrate nonahydrate, gallium nitrate hydrate, and indium nitrate trihydrate.

In the present invention, the metal (A) is preferably a metal belonging to Group 11, and more preferably silver, because this increases the ethanol conversion rate and the butadiene selectivity, thereby improving the butadiene yield.

In the present invention, the content of the metal (A) is preferably 0.1 to 50 mass%, more preferably 0.1 to 40 mass%, and even more preferably 0.2 to 30 mass%, relative to the mass of the carrier A.
Here, the "content" of the metal (A) and the metal (B) described later can be measured, for example, by ICP or fluorescent X-ray.

[Solid catalyst B]
The solid catalyst B used in the production method of the present invention is a solid catalyst comprising at least one metal (B) selected from the group consisting of metals belonging to groups 3, 4 and 5 supported on a support B.

<Carrier B>
The carrier B used in the solid catalyst B is not particularly limited as long as it can support the metal (B) described later. Specific examples thereof include those similar to the carrier A described above, and preferred embodiments thereof are also similar.

<Metal (B)>
The metal oxide (B) contained in the solid catalyst of the present invention is an oxide of at least one metal selected from the group consisting of metals belonging to Groups 3, 4 and 5.
Specific examples of metals belonging to Group 3 include scandium (Sc) and yttrium (Y).
Specific examples of metals belonging to Group 4 include titanium (Ti), zirconium (Zr), and hafnium (Hf).
Specific examples of metals belonging to Group 5 include vanadium (V), niobium (Nb), and tantalum (Ta).

Here, the raw material of the metal belonging to Group 3 is not particularly limited, but examples thereof include nitrates, oxynitrates, acetates, oxyacetates, and hydrates thereof of metals selected from Group 3. Specific examples include Sc(NO ₃ ) ₂ and scandium nitrate pentahydrate.
The raw material of the metal belonging to Group 4 is not particularly limited, but examples thereof include nitrates, hydrochlorides, oxynitrates, acetates, oxyacetates, and hydrates thereof of metals selected from Group 4. Specific examples include ZrO( _NO3 ) ₂ , _ZrO ( _NO3 ) _2.2H2O , ZrO( _OCOCH3 ) ₂ , and _HfCl4 .
The raw material of the metal belonging to Group 5 is not particularly limited, but examples thereof include sulfates, oxysulfates, acetates, oxyacetates, hydrochlorides, and hydrates thereof of metals selected from Group 5. Specific examples include _VOSO4 , _VOSO4.nH2O , ( _CH3COO ) _2Ta , _{VCl3 , NbCl5} , and _TaCl5 .

In the present invention, because the ethanol conversion rate and butadiene selectivity are higher and the butadiene yield is improved, the metal (B) is preferably at least one metal selected from the group consisting of metals belonging to Groups 3 and 4, more preferably at least one metal selected from the group consisting of hafnium, zirconium, and scandium, and even more preferably at least one metal selected from the group consisting of hafnium oxide, zirconium oxide, and scandium oxide.

In addition, in the present invention, the content of the metal (B) is preferably 0.1 to 50 mass%, more preferably 0.1 to 40 mass%, and even more preferably 0.2 to 30 mass%, relative to the mass of the carrier B described above.

[Method for preparing solid catalyst]
The method for preparing the above-mentioned solid catalysts A and B is not particularly limited, and for example, known methods such as an impregnation method, a sol-gel method, etc. can be adopted. Among these, the impregnation method is preferred because the activity and selectivity of the resulting solid catalyst are high and the method is simple.
As the impregnation method, for example, a known method such as a spraying method, a coating method, a pore filling method, a selective adsorption method, etc. can be adopted. Specifically, a method can be mentioned in which a nitrate, an acetate, etc. of the metal that is the raw material of the above-mentioned metal (A) or metal (B) is dissolved in water, the obtained aqueous solution is impregnated into the above-mentioned carrier, and then the carrier is dried. The drying method and drying time are not particularly limited, but it is preferable to dry under reduced pressure at 60 to 80 ° C. In addition, after drying, it is preferable to calcine at a temperature of 200 to 600 ° C.
In addition to the above-mentioned preparation methods, there may be mentioned a method in which, for example, nitrates, acetates, etc. of metals serving as raw materials for the above-mentioned metal (A) or metal (B) are mixed, followed by treatment such as heating, concentration, hydrothermal synthesis, and drying/calcination.
The prepared catalyst may be subjected to molding, granulation, etc., if necessary, before use.

[Raw materials]
In the production method of the present invention, ethanol or a mixture of ethanol and acetaldehyde is used as the raw material for the target product, butadiene.
The raw material may be appropriately diluted and then contacted with the above-mentioned solid catalysts A and B.
Specific examples of the medium for diluting the raw material (hereinafter also referred to as the "dilution medium") include inert gases such as nitrogen, argon, and helium.
The raw material may also contain impurities other than ethanol, acetaldehyde, and the dilution medium.

When a mixture of ethanol and acetaldehyde is used as a raw material in the production method of the present invention, the mass ratio of ethanol to acetaldehyde (ethanol:acetaldehyde) is not particularly limited, but is preferably in the range of 19:1 to 1:9, and more preferably in the range of 16:4 to 2:8.

[Reaction conditions, etc.]
The production method of the present invention can be carried out by a known reaction system, which may be a flow system, a batch system, or the like, but is preferably carried out in a flow system from the viewpoint of productivity.
The production method of the present invention may be carried out in either a gas phase or a liquid phase, but is preferably carried out under gas phase conditions, from the viewpoints of being able to apply a high reaction temperature and improving the conversion rate of the raw materials.
If desired, the catalyst may be reduced before the start of the reaction. For example, the catalyst may be reduced in a hydrogen stream at 200 to 500° C., and then the butadiene production step may be carried out by contacting the catalyst with the raw material.

Methods for contacting the raw material with the solid catalyst include, for example, a suspension bed method, a fluidized bed method, a fixed bed method, etc. In addition, the present invention may be either a gas phase method or a liquid phase method, but it is preferable to use a gas phase method.

When the reaction is carried out in the gas phase, the raw material gas (e.g., ethanol gas, preferably a mixture of ethanol gas and acetaldehyde gas) may be supplied to the reactor without dilution, or may be appropriately diluted with an inert gas such as nitrogen, helium, argon, or water vapor before being supplied to the reactor.

Regarding the reaction temperature, the temperature when the raw material is brought into contact with the solid catalyst A is preferably 250 to 400° C., and the temperature when the raw material is brought into contact with the solid catalyst B is preferably 350 to 500° C., because the ethanol conversion rate and the butadiene selectivity are higher and the butadiene yield is further improved. In particular, the temperature when the raw material is brought into contact with the solid catalyst B is preferably more than 400° C. and not more than 500° C., because the ethanol conversion rate and the butadiene selectivity are higher and the butadiene yield is further improved.
The reaction pressure can be appropriately set within a wide range from normal pressure to high pressure, but is preferably set to 1.0 MPa or less from the viewpoints of production efficiency and apparatus configuration.

The contact time between the raw material and the solid catalyst can be controlled by adjusting the feed rate of the raw material, and the weight hourly space velocity (WHSV) per unit catalyst is preferably 1.0 to 40 g raw material/g-cat·h, and more preferably 2.0 to 20 g raw material/g-cat·h.

After the reaction is complete, the reaction products can be separated and purified into light gases, C4 fractions, heavy fractions, water, ethanol, acetaldehyde, etc., using separation methods such as distillation, extraction, membrane separation, or a combination of these.

[Butadiene production equipment]
The butadiene production apparatus of the present invention (hereinafter also referred to as "the production apparatus of the present invention") is an apparatus for producing butadiene from ethanol or a mixture of ethanol and acetaldehyde, and has a reactor A and a reactor B connected to the reactor A.
In the production apparatus of the present invention, the reactor A is a reactor packed with a solid catalyst A comprising at least one metal (A) selected from the group consisting of metals belonging to groups 11, 12 and 13 supported on a carrier, and the reactor B is a reactor packed with a solid catalyst B comprising at least one metal (B) selected from the group consisting of metals belonging to groups 3, 4 and 5 supported on a carrier.
Moreover, the production apparatus of the present invention is a production apparatus in which ethanol or a mixture of ethanol and acetaldehyde is passed through the above-mentioned reactor A and then the above-mentioned reactor B.
The solid catalyst A packed in the reactor A and the solid catalyst B packed in the reactor B are the same as the solid catalyst A and the solid catalyst B explained in the production method of the present invention, respectively.

FIG. 1 is a schematic diagram showing an example of an embodiment of the butadiene production apparatus of the present invention.
The butadiene production apparatus 10 shown in FIG. 1 has a reactor A1 and a reactor B2 connected to the reactor A1.
1 has a liquid feed pump P, and the liquid feed pump P can be used to pass the raw material ethanol or a mixture of ethanol and acetaldehyde through the reactor A1 and the reactor B2 in this order. The position and function of the liquid feed pump P are not particularly limited as long as the raw material can be passed through the reactor A1 and the reactor B2 in this order.
The butadiene production apparatus 10 shown in FIG. 1 also has a gas cylinder 3 for adjusting the reaction atmosphere in the reactor A1 and the reactor B2.
Moreover, the butadiene production apparatus 10 shown in FIG. 1 has a heater 4 for adjusting the temperature inside the reactor, in each of the reactor A1 and the reactor B2.
The butadiene production apparatus 10 shown in FIG. 1 further includes a gas chromatography analyzer 5 for analyzing the product downstream of the reactor B2.

The present invention will be described in more detail below with reference to examples. The materials, amounts used, ratios, processing contents, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the examples shown below.

Example 1-1
Aqueous solution A1 was prepared by dissolving 0.211 g of AgNO ₃ (Ag salt) in 5 ml of water.
The prepared aqueous solution A1 was impregnated into mesoporous silica (manufactured by Fuji Silysia Chemical Ltd., product name: CARiACT G-6, average pore size: 6 nm), which was then dried at 110°C for 4 hours and further calcined at 500°C for 4 hours, thereby preparing a solid catalyst A1 in which Ag was supported on silica.
Also, 0.204 g of HfCl ₄ (Hf salt) was dissolved in 5 ml of water to prepare an aqueous solution B1.
The prepared aqueous solution B1 was impregnated into mesoporous silica (manufactured by Fuji Silysia Chemical Ltd., product name: CARiACT G-6, average pore size: 6 nm), which was then dried at 110°C for 4 hours and calcined at 500°C for 4 hours to prepare a solid catalyst B1 in which Hf was supported on silica.
Table 1 below shows the types and amounts of metals supported.

A fixed-bed flow reactor was filled with 0.3 g of the prepared solid catalyst A1 to prepare a reactor A.
Similarly, a reactor B was prepared by packing 0.3 g of the solid catalyst B1 into a fixed-bed flow reactor.
These reactors were connected, and _N2 gas was flowed at 5 to 15 ml/min from the upstream side of reactor A, and ethanol (EtOH) was added to the _N2 gas flow at a rate of 0.03 ml/min. The reaction temperatures in reactor A were 350°C, the reaction temperatures in reactor B were 425°C, and the gas was passed under atmospheric pressure at a weight hourly space velocity (WHSV) of 5.0 g-raw material/g-cat h. Table 1 below shows the raw materials, reaction temperatures, and weight hourly space velocities (WHSV).
The reaction was carried out for 2 hours, and the resulting product was analyzed using a gas chromatograph (manufactured by Shimadzu Corporation).
The conversion rate of the raw material, butadiene (BD) selectivity, BD yield, and BD productivity were calculated according to the following formulas. These results are shown in Table 1 below.
Conversion rate of raw material=(amount of raw material input−amount of unreacted raw material distilled)/(amount of raw material input)×100(%)
BD selectivity=(amount of butadiene produced)/(amount of raw material input−amount of unreacted raw material distilled)×100(C-mol%)
BD yield = (conversion rate of raw material) x (BD selectivity) ÷ 100 (C-mol%)
BD productivity=(mass of butadiene produced per hour)/(mass of catalyst used)(g-BD/g-cat·h)

Example 1-2
The raw material conversion rate, butadiene (BD) selectivity, BD yield, and BD productivity were calculated in the same manner as in Example 1-1, except that the reaction temperature in reactor B was changed to the temperature (400° C.) shown in Table 1 below. These results are shown in Table 1 below.

[Examples 1 to 3]
A solid catalyst B3 in which _ZrO2 was supported on silica was prepared in the same manner as in Example 1-1, except that an aqueous solution B3 in which 0.147 _g of ZrO( _NO3 ) _2.2H2O (Zr salt) was dissolved in 5 ml of water was used instead of the aqueous solution B1.
In addition, the raw material conversion rate, butadiene (BD) selectivity, BD yield, and BD productivity were calculated in the same manner as in Example 1-1, except that the solid catalyst B3 was used instead of the solid catalyst B1. These results are shown in Table 1 below.

[Examples 1 to 4]
The raw material conversion rate, butadiene (BD) selectivity, BD yield, and BD productivity were calculated in the same manner as in Example 1-3, except that the reaction temperature in reactor B was changed to the temperature (400° C.) shown in Table 1 below. These results are shown in Table 1 below.

[Examples 1 to 5]
A solid catalyst B5 in which Sc ₂ O ₃ was supported on silica was prepared in the same manner as in Example 1-1, except that an aqueous solution B5 in which 0.108 g of Sc(NO ₃ ) ₂ (Sc raw material) was dissolved in 5 ml of water was used instead of the aqueous solution B1.
In addition, the raw material conversion rate, butadiene (BD) selectivity, BD yield, and BD productivity were calculated in the same manner as in Example 1-1, except that the prepared solid catalyst B5 was used instead of the solid catalyst B1. These results are shown in Table 1 below.

Comparative Example 1-1
A solid catalyst C1 in which MgO was supported on silica was prepared in the same manner as in Example 1-1, except that an aqueous solution C1 in which 0.125 g of Mg(NO ₃ ) _{2.6H 2} O (Mg salt) was dissolved in 5 ml of water was used instead of the aqueous solution B1.
In addition, the raw material conversion rate, butadiene (BD) selectivity, BD yield, and BD productivity were calculated in the same manner as in Example 1-1, except that the prepared solid catalyst C1 was used instead of the solid catalyst B1. These results are shown in Table 1 below.

Comparative Example 1-2
A solid catalyst C2 in which ZnO was supported on silica was prepared in the same manner as in Example 1-1, except that an aqueous solution C2 in which 0.183 g of Zn(NO ₃ ) _{2.6H 2} O (Zn salt) was dissolved in 5 ml of water was used instead of the aqueous solution B1.
In addition, the raw material conversion rate, butadiene (BD) selectivity, BD yield, and BD productivity were calculated in the same manner as in Example 1-1, except that the solid catalyst C2 was used instead of the solid catalyst B1. These results are shown in Table 1 below.

Comparative Examples 1-3
A solid catalyst C3 in which Fe ₂ O ₃ was supported on silica was prepared in the same manner as in Example 1-1, except that an aqueous solution C2 in which 0.2485 g of Fe(NO ₃ ) _{3.9H 2} O (Fe salt) was dissolved in 5 ml of water was used instead of the aqueous solution B1.
In addition, the raw material conversion rate, butadiene (BD) selectivity, BD yield, and BD productivity were calculated in the same manner as in Example 1-1, except that the solid catalyst B1 was replaced with the prepared solid catalyst C3. These results are shown in Table 1 below.

Comparative Examples 1-4
A solid catalyst C4 in which Cr ₂ O ₃ was supported on silica was prepared in the same manner as in Example 1-1, except that an aqueous solution C2 in which 0.2462 g of Cr(NO ₃ ) _{3.9H 2} O (Cr salt) was dissolved in 5 ml of water was used instead of the aqueous solution B1.
In addition, the raw material conversion rate, butadiene (BD) selectivity, BD yield, and BD productivity were calculated in the same manner as in Example 1-1, except that the solid catalyst B1 was replaced with the prepared solid catalyst C4. These results are shown in Table 1 below.

Comparative Examples 1 to 5
The raw material conversion rate, butadiene (BD) selectivity, BD yield, and BD productivity were calculated in the same manner as in Example 1-1, except that the solid catalyst A1 prepared in Example 1-1 was used in reactor B and the solid catalyst B1 prepared in Example 1-1 was used in reactor A. These results are shown in Table 1 below.

From the results shown in Table 1, it was found that when at least one metal not corresponding to the metal (B) selected from the group consisting of metals belonging to Groups 3, 4, and 5 was supported on a carrier as the solid catalyst B, the yield of butadiene was 20% or less (Comparative Examples 1-1 to 1-4).
In addition, it was found that when at least one metal (B) selected from the group consisting of metals belonging to Groups 3, 4, and 5 was supported on a carrier as the solid catalyst A, and at least one metal (A) selected from the group consisting of metals belonging to Groups 11, 12, and 13 was supported on a carrier as the solid catalyst B, the yield of butadiene was significantly reduced (Comparative Example 1-5).
In contrast, it was found that the yield of butadiene was improved when at least one metal (A) selected from the group consisting of metals belonging to Groups 11, 12, and 13 was supported on a carrier as the solid catalyst A, at least one metal (B) selected from the group consisting of metals belonging to Groups 3, 4, and 5 was supported on a carrier as the solid catalyst B, and the raw material was contacted with the solid catalyst A and then the solid catalyst B (Examples 1-1 to 1-5).
In particular, a comparison between Example 1-1 and Example 1-2 revealed that the yield of butadiene was further improved when the temperature at the time of contacting the raw material with the solid catalyst B was more than 400° C. and not more than 500° C.

[Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-4]
In Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-4, the raw material conversion, butadiene (BD) selectivity, BD yield, and BD productivity were calculated in the same manner as in Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-4, except that the reaction temperature in Reactor A was changed to the temperature (400° C.) shown in Table 2 below. These results are shown in Table 2 below.

The results shown in Table 2 indicate that even if the reaction temperature in reactor A is changed to 400°C, results similar to those shown in Table 1 can be obtained.

1. Reactor A
2 Reactor B
3 Gas cylinder 4 Heater 5 Gas chromatography analyzer P Liquid delivery pump

Claims (6)

A method for producing butadiene by obtaining butadiene from ethanol or a mixture of ethanol and acetaldehyde, comprising the steps of:
A method for producing butadiene, comprising contacting ethanol or a mixture of ethanol and acetaldehyde with a solid catalyst A comprising a carrier carrying silver as the metal (A) and a solid catalyst B comprising a carrier carrying hafnium as the metal (B) in that order to obtain butadiene. The method for producing butadiene according to claim 1, wherein the temperature when ethanol or a mixture of ethanol and acetaldehyde is brought into contact with the solid catalyst A is 250 to 400°C, and the temperature when it is brought into contact with the solid catalyst B is 350 to 500°C. The method for producing butadiene according to claim 1 or 2, wherein the temperature when ethanol or a mixture of ethanol and acetaldehyde is brought into contact with the solid catalyst B is greater than 400°C and less than or equal to 500°C. The method for producing butadiene according to any one of claims 1 to 3 , wherein the supports contained in the solid catalyst A and the solid catalyst B are both silica. the content of the metal (A) is 0.1 to 50 mass% based on the mass of the support contained in the solid catalyst A,
The method for producing butadiene according to any one of claims 1 to 4 , wherein the content of the metal (B) is 0.1 to 50 mass% based on the mass of the support contained in the solid catalyst B. An apparatus for producing butadiene from ethanol or a mixture of ethanol and acetaldehyde, comprising:
The reactor A includes a reactor B connected to the reactor A,
The reactor A is a reactor packed with a solid catalyst A in which silver as the metal (A) is supported on a carrier,
The reactor B is a reactor packed with a solid catalyst B in which hafnium as the metal (B) is supported on a carrier,
An apparatus for producing butadiene, wherein ethanol or a mixture of ethanol and acetaldehyde is passed through the reactor A and then the reactor B.