JP7316801B2 - Method for producing 1,3-butadiene - Google Patents

Description

The present invention is a novel 1,3-butadiene produced by using ethanol and crotonaldehyde as raw materials, which is an important raw material for synthetic rubber in many industrial fields including the automobile industry and electronic materials. related to the manufacturing method of

Conventionally, 1,3-butadiene has been produced mainly by refining the C4 fraction produced as a by-product in synthesizing ethylene from petroleum (= naphtha cracking). However, in recent years, instead of chemical industrial raw materials obtained from petroleum, chemical industrial raw materials derived from biomass-derived raw materials have attracted attention. For example, bioethanol derived from biomass such as sugar cane and corn is converted to 1,3-butadiene. There is a strong need for a technology that converts.

Methods for obtaining 1,3-butadiene using ethanol as a raw material include a method using MgO as a catalyst (Patent Document 1) and a method using a mixture of Al ₂ O ₃ and ZnO (mixture ratio: 60/40) as a catalyst (non Patent Document 1), a method using a catalyst having a magnesium silicate structure obtained by a hydrothermal synthesis method (Patent Document 2), and using a catalyst comprising a combination of a compound having a magnesium silicate structure and an oxygen-containing inorganic compound containing tin. A method (Patent Document 3) and the like are known.

On the other hand, as a method of obtaining 1,3-butadiene from ethanol and crotonaldehyde as raw materials, there is known a method of using a catalyst in which Cr and Ni or Co are supported on SiO ₂ as a carrier (Patent Document 4). However, the production technology is more delicate than naphtha cracking and has not been established, the catalyst is easily degraded by heat and recycling is difficult, so the cost increases, the ethanol conversion efficiency is low, and the yield of 1,3-butadiene is low. However, due to the low molecular weight, it is not possible to find an advantage that can compete with the production method using chemical industrial raw materials obtained from petroleum, and the current situation is that the practical application is not progressing.

U.S. Pat. No. 2,423,681 JP 2015-34151 A JP 2017-75107 A JP 2014-156408 A

Journal of Catalyst, Vol. 5, p. 152 (1967)

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing 1,3-butadiene by which 1,3-butadiene can be obtained in a simple and industrially advantageous manner from ethanol and crotonaldehyde.

As a result of intensive studies by the present inventors to solve the above problems, 1,3-butadiene can be obtained with good selectivity when ethanol and crotonaldehyde are brought into contact with a specific catalyst containing magnesium in a heated environment. It was also found that the selectivity can be relatively stably maintained for a long period of time. The present invention has been completed based on these findings.

That is, the present invention provides a method for producing 1,3-butadiene to obtain 1,3-butadiene by bringing a raw material containing ethanol and crotonaldehyde into contact with a catalyst under heating, wherein the catalyst has (i) a surface Provided is a method for producing 1,3-butadiene, which is a composite oxide catalyst in which an octahedral magnesium layer is exposed to the surface, or (ii) a supported catalyst in which silica is supported on magnesium oxide.

The (i) composite oxide catalyst having an octahedral magnesium layer exposed on the surface is obtained by (i-1) hydrothermally synthesized silica-magnesia or a Si—Mg composite oxide having a talc structure and alkali treatment. or (i-2) serpentine.

The hydrothermally synthesized silica-magnesia is preferably prepared by heating an acidic aqueous solution containing a magnesium compound and a silicon compound together with urea under pressure.

The hydrothermally synthesized silica-magnesia may contain a metal or metalloid element other than magnesium and silicon. In that case, the metal or metalloid element other than magnesium and silicon is preferably at least one selected from the group consisting of cobalt, nickel, copper, zinc, gallium, silver and indium. Also, the total content of metals or metalloid elements other than magnesium and silicon is, for example, 0.1 to 5% by weight of the entire catalyst.

The Si—Mg composite oxide having a talc structure is preferably talc or natural sepiolite.

The alkali treatment is preferably treatment with an aqueous potassium hydroxide solution.

In the (i) composite oxide catalyst having an octahedral magnesium layer exposed on the surface, the elemental ratio of magnesium to silicon (molar ratio: Mg/Si) is preferably 0.7 to 2.0.

In the supported catalyst (ii) in which silica is supported on magnesium oxide, the supported catalyst preferably has a structure in which magnesium oxide is covered with a monolayer of silica.

In the (ii) supported catalyst in which silica is supported on magnesium oxide, the method for supporting silica is preferably a CVD method.

The (ii) supported catalyst in which silica is supported on magnesium oxide may contain a metal or metalloid element other than magnesium and silicon. In that case, the metal or metalloid element other than magnesium and silicon is preferably at least one selected from the group consisting of cobalt, nickel, copper, zinc, gallium, silver and indium. Also, the total content of metals or metalloid elements other than magnesium and silicon is, for example, 0.1 to 5% by weight of the entire catalyst.

According to the method for producing 1,3-butadiene according to the present invention, 1,3-butadiene can be selectively produced from ethanol and crotonaldehyde by a simple method. In addition, the catalyst used in the present invention is resistant to heat deterioration and can be used repeatedly. Therefore, the method for producing 1,3-butadiene according to the present invention is suitable as a method for industrially producing 1,3-butadiene, which is an important raw material for synthetic rubber in many industrial fields, from ethanol and crotonaldehyde. can be used.

FIG. 2 is a diagram showing the structure of Si—Mg composite oxides [talc and sepiolite] having a talc structure. 1 is a diagram showing the structure of Serpentin; FIG. Serpentine includes lizardite (six-plate-like), chrysotile (fibrous), and antigorite (strip-like). FIG. 4 is a diagram showing an infrared absorption spectrum (νOH) of sepiolite; 4 is a diagram showing the structure of Mg ₃ —OH shown in FIG. 3; FIG. It is a figure showing the X-ray diffraction spectrum of talc and antigorite (a kind of Serpentin). The upper spectrum is antigorite, and the lower spectrum is talc. FIG. 2 shows X-ray diffraction spectra of catalysts obtained in Preparation Examples A3 to A6. FIG. 2 is a diagram showing X-ray diffraction spectra of supported catalysts in which silica is supported on magnesium oxide obtained in Preparation Examples B1 to B4 and B7. FIG. 2 is a diagram showing X-ray diffraction spectra of supported catalysts in which silica is supported on magnesium oxide, obtained in Preparation Examples B11 to B13. FIG. 2 shows X-ray diffraction spectra of supported catalysts in which silica is supported on magnesium oxide obtained in Preparation Examples B1, B17, B18, and B21. FIG. 3 is a diagram showing infrared absorption spectra in the skeleton vibration region of supported catalysts in which silica is supported on magnesium oxide, obtained in Preparation Examples B11 to B13. FIG. 2 is a diagram showing infrared absorption spectra of supported catalysts in which silica is supported on magnesium oxide obtained in Preparation Examples B1, B17, and B18. FIG. 2 is a diagram showing infrared absorption spectra in the skeleton vibration region of supported catalysts in which silica is supported on magnesium oxide obtained in Preparation Examples B1, B19, B20, and B21.

A method for producing 1,3-butadiene according to the present invention is a method for producing 1,3-butadiene in which 1,3-butadiene is obtained by bringing raw materials containing ethanol and crotonaldehyde into contact with a catalyst under heating, The catalyst is (i) a composite oxide catalyst having an octahedral magnesium layer exposed on the surface, or (ii) a supported catalyst in which silica is supported on magnesium oxide.

It is believed that the method for producing 1,3-butadiene of the present invention involves the following reaction steps. In addition to the steps described below, there is also a possible reaction route in which 1,3-butadiene is produced directly from ethanol.

_CH3CH2OH + _{CH3CH =} CHCHO
→ _CH3CHO + _CH3CH = _CHCH2OH (a)
_CH3CH = _CHCH2OH- > _CH2 =CHCH= _CH2 + _H2O (b)

[material]
The raw material of the present invention contains at least ethanol and crotonaldehyde. Using ethanol and crotonaldehyde as raw materials means supplying ethanol and crotonaldehyde from the outside into the reaction system.

Raw material ethanol is not particularly limited, and examples thereof include ethanol derived from biomass such as sugarcane and corn, and ethanol derived from petroleum or natural gas. In the present invention, it is particularly preferable to use biomass-derived ethanol because it can greatly contribute to the reduction of greenhouse gases. The raw material crotonaldehyde is not particularly limited, and may be obtained by any production method.

Moreover, the raw material of the present invention may contain acetaldehyde together with ethanol and crotonaldehyde. By containing acetaldehyde, the selectivity and yield of 1,3-butadiene can be improved.

The total content of ethanol and crotonaldehyde in the raw material (100% by weight) of the present invention is, for example, 50% by weight or more, preferably 70 to 100% by weight. In addition, the above-mentioned "raw material" does not include an inert gas (in the case of a liquid phase reaction, a solvent inert to the reaction).

The ratio of ethanol and crotonaldehyde to be used is, for example, 0.5 to 10, preferably 1 to 5, more preferably 1.2 to 3 as the former/latter (molar ratio).

[catalyst]
The catalyst used in the production method of the present invention (hereinafter sometimes referred to as “the catalyst of the present invention”) is (i) a composite oxide catalyst having an exposed octahedral magnesium layer on the surface, or (ii) magnesium oxide It is a supported catalyst in which silica is supported.

<(i) Composite oxide catalyst with octahedral magnesium layer exposed on the surface>
For the (i) composite oxide catalyst having an octahedral magnesium layer exposed on the surface, for example, (i-1) Si—Mg composite oxide having a hydrothermal synthesis silica-magnesia or talc structure is treated with an alkali. Catalysts with an exposed Mg-based octahedral sheet on the surface and (i-2) serpentine are included.

The hydrothermally synthesized silica-magnesia is produced, for example, by heating an aqueous solution (eg, acidic aqueous solution) containing a magnesium compound and a silicon compound in the presence of a homogeneous precipitant in a pressure vessel.

Examples of the magnesium compound include magnesium hydroxide, magnesium nitrate, and magnesium oxalate. These can be used individually by 1 type or in combination of 2 or more types.

Examples of the silicon compound include silicic acid (eg, colloidal silica, fumed silica, etc.), tetraethyl orthosilicate, and the like. These can be used individually by 1 type or in combination of 2 or more types.

Examples of the homogeneous precipitant include urea and hexamine. These can be used individually by 1 type or in combination of 2 or more types.

The amount of the uniform precipitant used is, for example, 1.2 mol or more, preferably 1.5 mol or more, per 1 mol of the magnesium compound. By using the uniform precipitant within the above range, the pH can be swung in a uniform state, and crystal nuclei can be uniformly generated.

The hydrothermal synthesis of the magnesium compound and the silicon compound is preferably carried out in the presence of an acidic aqueous solution (e.g., nitric acid aqueous solution, sulfuric acid aqueous solution, etc.), and the amount of the acidic aqueous solution used is, for example, the total weight of the magnesium compound and the silicon compound. It is about 0.5 to 5 times the weight, preferably 0.8 to 1.5 times the weight.

The reaction temperature during hydrothermal synthesis of the magnesium compound and silicon compound is, for example, 80° C. or higher (eg, 80 to 150° C.), preferably 90° C. or higher (eg, 90 to 130° C.). The pressure during the reaction is, for example, 0.1 MPa or higher, preferably 0.3 MPa or higher, and more preferably 0.5 MPa or higher. The reaction time is, for example, 24 hours or longer, preferably 48 hours or longer.

After hydrothermal synthesis is completed, for example, drying, firing (for example, heating at 120 to 200° C. for about 0.5 to 3.0 hours and further heating at 450 to 600° C. for about 1 to 5 hours), pulverization, etc. are performed. Thus, the hydrothermally synthesized silica-magnesia can be produced.

The hydrothermally synthesized silica-magnesia may contain metals or metalloid elements other than magnesium and silicon as constituent elements.

Examples of metal or metalloid elements other than magnesium and silicon (hereinafter sometimes referred to as "other elements") include cobalt, nickel, copper, zinc, gallium, silver, and indium. One of these may be used, or two or more of them may be used.

The total content of the other elements (eg, at least one element selected from the group consisting of cobalt, nickel, copper, zinc, gallium, silver, and indium) is, for example, 0.1 to 0.1 based on the weight of the entire catalyst. 5% by weight, preferably 0.2 to 2.5% by weight, more preferably 0.5 to 1% by weight. If the total content of the other elements exceeds the above range, only a specific stage of the reaction process described above is promoted excessively, or side reactions are promoted, and the selectivity of 1,3-butadiene tends to decrease. There is The other element can be introduced by adding a compound containing the other element in addition to the magnesium compound and the silicon compound during hydrothermal synthesis.

In the Si—Mg composite oxide having the talc structure, the talc structure includes an octahedral magnesium layer (brucite [Mg(OH) ₂ ] layer) and a tetrahedral silicon layer (silica (SiO ₂ ) layer). ), and is a structure in which electrically neutral layers are piled up by weak van der Waals forces. Si—Mg composite oxides having such a talc structure include talc [Mg ₃ Si ₄ O ₁₀ .(OH) ₂ ] (see FIG. 1), sepiolite (for example, natural sepiolite) (Sepiolite) [Mg _{8 Si12O30} .(OH) ₄ ( _H2O ) _4.6H2O ] (see FIG _. 1) _.

The catalyst (i-1) is prepared by subjecting the hydrothermally synthesized silica-magnesia or Si—Mg composite oxide having a talc structure to alkali treatment, and has an octahedral magnesium layer ( Mg-based octahedral sheet) is exposed.

Examples of the alkali used for the alkali treatment include ammonia water, lithium hydroxide aqueous solution, potassium hydroxide aqueous solution, sodium hydroxide aqueous solution and the like. Among these, potassium hydroxide aqueous solution is particularly preferable. The concentration of the alkaline aqueous solution is not particularly limited, but is, for example, 0.1 to 30% by weight, preferably 1 to 20% by weight, more preferably 5 to 10% by weight. The amount of the alkaline aqueous solution used is, for example, 25 to 300 times by weight, preferably 50 to 200 times by weight, that of hydrothermally synthesized silica-magnesia or Si--Mg composite oxide having a talc structure. The alkali treatment temperature is, for example, 100 to 200°C, preferably 120 to 180°C. The alkali treatment time is, for example, 10 to 100 hours, preferably 15 to 30 hours. After the alkali treatment is completed, the alkali-treated hydrothermally synthesized silica-magnesia can be produced by, for example, drying and pulverizing.

The exposure of the magnesium layer on the surface of the catalyst (i-1) can be confirmed by the infrared absorption spectrum of the alkali-treated sepiolite (see FIG. 3). That is, in the infrared absorption spectrum, the ratio of the absorbance of the peak around the wavelength 3684 cm ⁻¹ derived from Mg—OH to the absorbance of the peak around the wavelength 3716 cm ⁻¹ derived from Si—OH (former/latter) is 2.7. If it is above (preferably above 2.8), it can be said that the magnesium layer is exposed on the surface. The ratio in sepiolite (natural sepiolite) is 1.63. In addition, it was confirmed by X-ray diffraction that the magnesium layer was exposed on the surface of alkali-treated hydrothermally synthesized silica-magnesia and alkali-treated Si-Mg composite oxide having a talc structure other than sepiolite. (See FIGS. 5 and 6). That is, after the alkali treatment, the peaks of the planes perpendicular to the c-axis of the talc crystal, such as the (002) plane near 9 deg and the (006) plane near 28 deg, are slightly attenuated, the peak derived from serpentine near 24 deg, and the peak derived from serpentine near 38 deg. brucite-derived pattern is confirmed.

The catalyst (i-2) is serpentine [Mg ₃ (Si ₂ O ₅ )(OH) ₄ ] (see FIG. 2). Serpentine can be synthesized by a known method. For example, magnesium oxide is heated with water to form magnesium hydroxide, this magnesium hydroxide and silicon oxide are mixed in water to prepare a homogeneous solution, and this homogeneous solution is heated to 200° C. or higher, preferably 210 to 300° C. (for example, 230° C.) for a predetermined time (for example, 50 to 200 hours), serpentine can be obtained.

In the (i) composite oxide catalyst having an octahedral magnesium layer exposed on the surface, the elemental ratio of magnesium and silicon (molar ratio: Mg/Si) is, for example, 0.7 to 2.0, preferably 0.8. to 1.8, more preferably 0.9 to 1.5. By setting the Mg/Si element ratio to 2.0 or less, the specific surface area of the catalyst can be increased, and the conversion rate of ethanol and crotonaldehyde can be increased. Further, by setting the Mg/Si element ratio to 0.7 or more, the amount of acid sites on the catalyst can be reduced, and the dehydration reaction (side reaction) from ethanol to ethylene can be suppressed.

<(ii) Supported catalyst in which silica is supported on magnesium oxide>
In (ii) a supported catalyst in which silica is supported on magnesium oxide, magnesium oxide used as a support is not particularly limited, but one having a large specific surface area is preferable. The specific surface area of magnesium oxide is, for example, 50 m ² /g or more, preferably 100 m ² /g or more, more preferably 200 m ² /g or more.

The magnesium oxide can be produced, for example, by heating an aqueous solution (eg, acidic aqueous solution) containing a magnesium compound in the presence of a uniform precipitant in a pressure vessel (hydrothermal synthesis).

Examples of the magnesium compound include magnesium hydroxide, magnesium nitrate, and magnesium oxalate. These can be used individually by 1 type or in combination of 2 or more types.

Examples of the homogeneous precipitant include urea and hexamine. These can be used individually by 1 type or in combination of 2 or more types.

The amount of the uniform precipitant used is, for example, 1.2 mol or more, preferably 1.5 mol or more, per 1 mol of the magnesium compound. By using the uniform precipitant within the above range, the pH can be swung in a uniform state, and crystal nuclei can be uniformly generated.

The hydrothermal synthesis of magnesium oxide is preferably carried out in the presence of an acidic aqueous solution (e.g., aqueous nitric acid solution, aqueous sulfuric acid solution, etc.). About twice the weight, preferably 0.8 to 1.5 times the weight.

The reaction temperature during hydrothermal synthesis of magnesium oxide is, for example, 80° C. or higher (eg, 80 to 150° C.), preferably 90° C. or higher (eg, 90 to 130° C.). The pressure during the reaction is, for example, 0.1 MPa or higher, preferably 0.3 MPa or higher, and more preferably 0.5 MPa or higher. The reaction time is, for example, 24 hours or longer, preferably 48 hours or longer.

After hydrothermal synthesis is completed, for example, by firing (for example, heating at 120 to 200° C. for about 0.5 to 3.0 hours and further heating at 450 to 600° C. for about 1 to 5 hours), crushing, etc. , magnesium oxide can be produced.

Examples of the method for supporting silica (SiO ₂ ) on the magnesium oxide include, for example, a method of impregnating magnesium oxide with an organic silicon compound such as tetraethylorthosilicate, drying, calcining, pulverizing, etc. (IMP, imprenation); A method of tableting a powder obtained by grinding and mixing magnesium oxide and fumed silica and subjecting it to pulverization (MM, mechanical mixture), wet kneading magnesium oxide and fumed silica, then firing A method of pulverizing (WK, wet kneading), in which an organosilicon compound having a vapor pressure is allowed to stand together with magnesium oxide in a desiccator at a predetermined temperature, thereby exposing the magnesium oxide to the organosilicon compound vapor corresponding to the vapor pressure. A method (CVD, chemical vapor deposition) of firing and pulverizing afterward may be used. Among these, CVD is particularly preferred.

In the above CVD, when the magnesium oxide is exposed to the vapor of the organosilicon compound at room temperature (eg, 25° C.), the exposure time is preferably 10 minutes to 1200 minutes, more preferably 20 minutes to 600 minutes. Note that the higher the CVD temperature, the more silica deposits on the magnesium oxide surface in a shorter CVD time. After exposure to steam, for example, by firing (for example, heating at 450 to 600° C. for about 1 to 5 hours), pulverization, etc., the above-mentioned (ii) supported catalyst in which silica is supported on magnesium oxide can be produced. can.

Examples of the organosilicon compound include tetramethylsilane, tetramethoxysilane, tetraethylorthosilicate, and the like. These can be used individually by 1 type or in combination of 2 or more types.

The magnesium oxide having SiO ₂ supported on the surface may contain metals or metalloid elements other than magnesium and silicon as constituent elements.

Examples of metal or metalloid elements other than magnesium and silicon (hereinafter sometimes referred to as "other elements") include cobalt, nickel, copper, zinc, gallium, silver, and indium. One of these may be used, or two or more of them may be used.

The total content of the other elements (eg, at least one element selected from the group consisting of cobalt, nickel, copper, zinc, gallium, silver, and indium) is, for example, 0.1 to 0.1 based on the weight of the entire catalyst. 5% by weight, preferably 0.2 to 2.5% by weight, more preferably 0.5 to 1% by weight. If the total content of the other elements exceeds the above range, only a specific stage of the reaction process described above is promoted excessively, or side reactions are promoted, and the selectivity of 1,3-butadiene tends to decrease. There is

In the (ii) supported catalyst in which silica is supported on magnesium oxide, the supported catalyst preferably has a structure in which magnesium oxide is covered with a monolayer (single layer) of silica. The reason why the silica layer covers the magnesium oxide is that a band derived from CO ₃ ^2- adsorbed on the magnesium oxide surface is not observed at 865 cm ⁻¹ in the infrared absorption spectrum, and at 1029 cm ⁻¹ . It can be confirmed by the presence of a band derived from Si—O—Si in-plane vibration at the position. The fact that the silica layer is a monolayer means that in the infrared absorption spectrum, bands derived from the three-dimensional structure of amorphous silica are not seen at positions of 1100 cm ^-1 and 805 cm ^-1 , and in the X-ray diffraction pattern, It can be confirmed by not seeing a halo peak derived from amorphous silica at the position of 30 deg.

In the (ii) supported catalyst in which silica is supported on magnesium oxide, the elemental ratio of silicon and magnesium (molar ratio: Si/Mg) varies depending on the specific surface area of magnesium oxide, but is for example 0.01 to 0.5. , preferably 0.03 to 0.3, more preferably 0.05 to 0.25. By setting the Si/Mg element ratio to 0.5 or less, excessive adsorption of Si to the basic sites of the catalyst can be suppressed, and dehydration reaction (side reaction) from ethanol to ethylene can be suppressed. Further, by setting the Si/Mg element ratio to 0.01 or more, the conversion rate of ethanol and crotonaldehyde can be increased.

The catalyst of the present invention is usually used in the form of granules (including molded articles). The particle size of the catalyst of the present invention is not particularly limited, but the average particle size is, for example, 0.05 to 10 mm, preferably 0.5 to 5 mm, more preferably 0.85 to 2 mm. In addition, the particle size of the catalyst of the present invention is preferably 20 mesh (opening: 0.85 mm) or more and 10 mesh (opening: 2.0 mm) or less (i.e., passing through a 10 mesh sieve, the size of the particles remaining on the sieve).

[Method for producing 1,3-butadiene]
In the method for producing 1,3-butadiene of the present invention, 1,3-butadiene is obtained by bringing a raw material containing ethanol and crotonaldehyde into contact with the above catalyst.

The production method of the present invention can be carried out by a conventional method such as a batch system, a semi-batch system, or a continuous system. When a batch system or a semi-batch system is adopted, the usage rate of raw materials can be made extremely high. In addition, since the production method of the present invention uses the above catalyst, even if a continuous system is adopted, the raw materials ethanol and crotonaldehyde can be converted more efficiently than conventional methods, and unreacted raw materials are added to the reaction system. By recycling, the usage rate of raw materials ethanol and crotonaldehyde can be improved to an extremely high level. Therefore, it is preferable to employ a continuous system capable of separating and recovering 1,3-butadiene simply and efficiently.

Examples of methods for bringing the raw material into contact with the catalyst include a suspended bed method, a fluidized bed method, and a fixed bed method. Further, the present invention may be either a vapor phase method or a liquid phase method. In the present invention, in particular, the above catalyst is packed in a reaction tube to form a catalyst layer, and a raw material is prepared because it is possible to synthesize a large amount, the operation workload is light, and the recovery and regeneration of the catalyst are simple. It is preferable to use a fixed-bed gas-phase continuous flow reactor in which a gas is passed through and reacted in the gas phase.

When the reaction is carried out in the gas phase, the raw material gas may be supplied to the reactor without being diluted, or may be appropriately diluted with an inert gas such as nitrogen, helium, argon, or carbon dioxide before being supplied to the reactor. good.

The reaction temperature is, for example, about 300 to 450°C, preferably 350 to 430°C. By setting the reaction temperature to 300° C. or higher, high catalytic activity can be obtained, the reaction rate can be increased, and the production efficiency can be improved. On the other hand, by setting the reaction temperature to 450° C. or less, deterioration of the catalyst can be suppressed.

The reaction pressure can be appropriately set within a wide range from normal pressure to high pressure. From the viewpoint of production efficiency, apparatus configuration, etc., it is preferable to set the pressure to 1 MPa or less.

When a continuous system is employed, the feed rate of the raw material to the catalyst (W / F [g min / mL] = (catalyst weight) / (raw material feed rate)) is, for example, 0.001 to 0.1 g min / mL, preferably 0.005 to 0.05 g.min/mL, particularly preferably 0.008 to 0.04 g.min/mL.

After completion of the reaction, the reaction product can be separated and purified by separation means such as filtration, concentration, distillation, extraction, etc., or a combination of these separation means.

In the catalyst of the present invention, the catalytically active component is less likely to elute into the reaction solution, and even when the catalyst and the raw material are brought into contact with the suspension bed method or the fluidized bed method, physical separation such as filtration and centrifugation from the reaction solution can be performed. It can be easily recovered by a simple separation technique. In addition, unreacted raw materials may be recovered and reused.

In addition, the catalyst of the present invention is subjected to a regeneration treatment in a reactor, for example, at about 350 to 500° C., preferably at 450 to 500° C., with air circulating under heating for, for example, 1 to 24 hours, preferably 3 to 6 hours. By performing, the catalytic activity can be recovered to 90% or more of the unused catalyst and can be reused. Therefore, 1,3-butadiene can be efficiently produced for a long period of time by carrying out the regeneration treatment when the catalytic activity has decreased to some extent.

In the method for producing 1,3-butadiene of the present invention, since a raw material containing ethanol and crotonaldehyde is brought into contact with the catalyst, the conversion rate of ethanol and crotonaldehyde is excellent, and 1,3-butadiene is produced with excellent selectivity. can be manufactured. In addition, even if it is operated continuously for a long time, the catalyst is less likely to deteriorate and the selectivity of 1,3-butadiene is less likely to decrease.

The production method of the present invention can selectively produce 1,3-butadiene. The selectivity of 1,3-butadiene after 10 minutes (based on all raw materials) is, for example, 40% or more, preferably 60% or more, and more preferably 75% or more when the catalyst (i) is used. When catalyst (ii) is used, it is, for example, 8% or more, preferably 15% or more, more preferably 20% or more, and particularly preferably 40% or more. In addition, the production method of the present invention is excellent in the conversion rate of ethanol, for example, when the reaction is performed under the conditions of a reaction temperature of 400 ° C. and W / F = 0.01 g min / mL, conversion of ethanol 10 minutes after the start of the reaction When the catalyst (i) is used, the ratio is, for example, 60% or more, preferably 70% or more, more preferably 80% or more, and particularly preferably 93% or more, and when the catalyst (ii) is used, For example, it is 15% or more, preferably 30% or more, more preferably 60% or more, particularly preferably 80% or more.

Since the method for producing 1,3-butadiene of the present invention has a high selectivity for 1,3-butadiene as described above, by recycling unreacted ethanol and crotonaldehyde in the reaction system, it is possible to use ethanol and crotonaldehyde. The rate can be improved, and 1,3-butadiene can be produced industrially efficiently.

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

Preparation A1
Sepiolite from Aldrich (see FIG. 1) was used as catalyst (A1).

Preparation A2
1.0 g of sepiolite (manufactured by Aldrich) and 50 mL of a 5% by weight potassium hydroxide aqueous solution were placed in a pressure vessel having an internal volume of 100 mL, sealed, and then heated at 70° C. for 24 hours. The gel formed in the pressure vessel was washed with deionized water, collected by filtration, and dried at 60°C for 2 days to obtain a white solid. This solid was pulverized to obtain alkali-treated sepiolite crystals. This powder was tableted and solidified, pulverized, and classified by 10-20 mesh to obtain a catalyst (A2).

Preparation A3
5.49 g of magnesium nitrate hexahydrate (manufactured by Kanto Kagaku Co., Ltd.) and 2.00 g of urea were added to 10 mL of a 0.1 M nitric acid aqueous solution and stirred until dissolved. 5 mL of tetraethyl orthosilicate (manufactured by Aldrich) was added to the resulting solution and stirred until the solution became homogeneous. The homogenized solution was transferred to a 100 mL pressure vessel, sealed, and then heated at 100° C. for 48 hours. The gel that formed in the pressure vessel was recovered by filtration and dried at 60°C for 2 days to give a white solid. This solid was pulverized and calcined at 170° C. for 1 hour and at 500° C. for 2 hours to obtain magnesium silicate crystals. This powder was tableted, solidified, crushed, and classified by 10-20 mesh to obtain a catalyst (A3) [SiO ₂ --MgO; hydrothermal synthesis silica-magnesia; Mg/Si=1].

Preparation A4
0.5 g of the catalyst (A3) [SiO ₂ —MgO; hydrothermal silica-magnesia; was added, and after sealing, the mixture was stirred at 145° C. for 24 hours. The gel formed in the pressure vessel was washed with deionized water, collected by filtration, and dried at 110° C. overnight to obtain a white solid. This solid was pulverized to obtain alkali-treated hydrothermally synthesized silica-magnesia. This powder was tableted, solidified, pulverized, and classified by 10-20 mesh to obtain a catalyst (A4) [NaOH-treated SiO ₂ -MgO].

Preparation A5
0.5 g of the catalyst (A4) [NaOH-treated SiO ₂ —MgO] obtained in Preparation Example A4 and 50 mL of a 5.2 M sodium hydroxide aqueous solution were placed in a pressure vessel with an internal volume of 100 mL, sealed, and then heated at 145° C. for 24 hours. Stirred. The gel formed in the pressure vessel was washed with deionized water, collected by filtration, and dried at 110° C. overnight to obtain a white solid. This solid was pulverized to obtain alkali-treated hydrothermally synthesized silica-magnesia. This powder was tableted, solidified, pulverized, and classified by 10-20 mesh to obtain a catalyst (A5) [SiO ₂ -MgO treated twice with NaOH].

Preparation A6
0.5 g of the catalyst (A3) [SiO ₂ —MgO; hydrothermal silica-magnesia; was added, and after sealing, the mixture was stirred at 145° C. for 24 hours. The gel formed in the pressure vessel was washed with deionized water, collected by filtration, and dried at 110° C. overnight to obtain a white solid. This solid was pulverized to obtain alkali-treated hydrothermally synthesized silica-magnesia. This powder was tableted, solidified, pulverized, and classified by 10-20 mesh to obtain a catalyst (A6') [KOH-treated SiO ₂ -MgO].
0.5 g of the catalyst (A6′) [KOH-treated SiO ₂ —MgO] obtained by steam and 50 mL of a 5.2 M potassium hydroxide aqueous solution were placed in a pressure vessel with an internal volume of 100 mL, sealed, and then stirred at 145° C. for 24 hours. bottom. The gel formed in the pressure vessel was washed with deionized water, collected by filtration, and dried at 110° C. overnight to obtain a white solid. This solid was pulverized to obtain alkali-treated hydrothermally synthesized silica-magnesia. This powder was tableted, solidified, pulverized, and classified by 10-20 mesh to obtain a catalyst (A6) [SiO ₂ -MgO treated twice with KOH].

Preparation A7
50 mL of ion-exchanged water was added to 1.49 g of magnesium oxide (manufactured by Merck), and the mixture was heat-treated at 80° C. for 1 hour to obtain magnesium hydroxide. 20 mL of ion-exchanged water was added to 1.48 g of the obtained magnesium hydroxide and silicon oxide (manufactured by Cabosil), and the mixture was stirred until the solution became uniform. The homogenized solution was transferred to a 100 mL pressure vessel, sealed, and then heated at 230° C. for 120 hours. The gel that formed in the pressure vessel was collected by filtration and dried at 110° C. overnight to yield serpentine crystals as shown in FIG. This powder was tableted, solidified, pulverized, and classified by 10-20 mesh to obtain catalyst (A7) [Serpentin; Mg/Si=1.5].

Reference Examples 1-1 to 1-2, Examples 1-1 to 1-5
0.05 g of the catalyst shown in Table 1 was packed in a 6 mmφ SUS reaction tube connected to a fixed bed gas phase continuous flow reactor (reactor), and was heated in an electric furnace under N ₂ flow at 100 mL / min. Heated to 500°C.
After pretreatment for 1 hour, the electric furnace temperature was kept at 400 ° C., and 3.6% ethanol + 1.8% crotonaldehyde / N ₂ gas was added at a rate of W / F = 0.01 g · min · mL ^-1 was allowed to flow through the reactor and reacted. After gas-liquid separation was performed on the gas at the outlet of the reactor, the gas was cooled in a cooler and the condensed liquid was recovered.
After a predetermined period of time from the start of the reaction, the gas composition at the outlet of each reactor was analyzed using a gas chromatograph and a Karl Fischer moisture meter.
As the catalyst, Reference Example 1-1 is Preparation Example A1, Example 1-1 is Preparation Example A2, Reference Example 1-2 is Preparation Example A3, and Examples 1-2 to 1-5 are Preparation Examples A4 to The catalysts obtained respectively in A7 were used.
Table 1 shows the conversion rate (%) (ethanol conversion rate, crotonaldehyde conversion rate, total raw material conversion rate), yield (%) based on all raw materials (butadiene yield, butadiene + acetaldehyde yield), and conversion rate based on all raw materials. Selectivity (%) (butadiene selectivity, butadiene + acetaldehyde selectivity), crotonaldehyde-based yield (%) (butadiene yield), and crotonaldehyde-based selectivity (butadiene selectivity) are shown. In the table, "butadiene" indicates 1,3-butadiene.

In some cases, the yield and selectivity based on crotonaldehyde exceed 100%. This is considered to be due to the presence of 1,3-butadiene produced directly from the raw material ethal.

As shown in Table 1, the catalyst (Example 1-1) in which sepiolite (Si—Mg composite oxide having a talc structure) was treated with alkali to expose the magnesium layer on the surface was not subjected to alkali treatment. It showed high yield and selectivity compared to sepiolite (Reference Example 1-1).
In addition, the catalysts (Examples 1-2 and 1-3) in which the hydrothermally synthesized silica-magnesia was treated with alkali to expose the magnesium layer on the surface were the hydrothermally synthesized silica-magnesia ( Higher yield and selectivity than in Reference Example 1-2) were exhibited.
Furthermore, serpentine, which originally has a magnesium layer on its surface, exhibits high yields and selectivities without being subjected to alkali treatment, and there is a tendency that the decrease in catalytic activity (butadiene yield, butadiene selectivity) is suppressed. rice field.
In the catalyst used in Example 1-1, the exposure of the magnesium layer on the surface was confirmed by measuring the infrared absorption spectrum, and measuring the absorbance of the peak near the wavelength 3684 cm ^-1 derived from Mg-OH and the Si- It was confirmed by calculating the absorbance ratio of the peak around the wavelength of 3716 cm ^-1 derived from OH. The ratio (former/latter) was 1.63 in Reference Example 1-1 and 3.28 in Example 1-1. In the catalysts used in Examples 1-2 to 1-5, the exposure of the magnesium layer on the surface was confirmed by measuring the X-ray diffraction spectrum and detecting a peak around 24 deg derived from serpentine or 38 deg derived from brucite. This was confirmed by the presence of nearby peaks. In Reference Example 1-2, the presence of peaks near 24deg and 38deg cannot be confirmed, whereas in Examples 1-2, 1-3, 1-4, and 1-5, the presence of peaks near 24deg and 38deg is confirmed. did it.

Preparation B1
Magnesium oxide from MERCK was used as catalyst (B1). The specific surface area of this magnesium oxide (B1) is 65 m ² /g.

Preparation B2
1.0 g of catalyst (B1) and 0.35 g of tetraethyl orthosilicate were placed in an open container, heated at 80° C. for 1 hour and at 100° C. overnight with stirring, dried, and then calcined at 500° C. for 2 hours. to give a white solid. This solid was pulverized, solidified by tableting, pulverized, and classified by 10-20 mesh to obtain a catalyst (B2) (IMP, imprenation).

Preparation B3
1.0 g of the catalyst (B1) and 0.10 g of fumed silica were placed in a pulverizing mill and ground and mixed for 30 minutes to obtain a powder. This powder was tableted and solidified, pulverized, and classified by 10-20 mesh to obtain a catalyst (B3) (MM, mechanical mixture).

Preparation B4
1.0 g of the catalyst (B1), 0.10 g of fumed silica and 1 cc of distilled water were placed in a pulverizing mill, wet kneaded for 30 minutes, and then calcined at 500° C. for 2 hours to obtain a white solid. This solid was pulverized, solidified by tableting, pulverized, and classified by 10-20 mesh to obtain a catalyst (B4) (WK, wet kneading).

Preparation B5
1.0 g of the catalyst (B1) was placed in the sample holder, and after the closed system was evacuated, 5.00 g of tetraethyl orthosilicate was introduced into the system, and the system was allowed to stand at room temperature for 10 minutes under the vapor pressure of tetraethyl orthosilicate. . After evacuation, the crystals in the obtained sample holder were calcined at 500° C. for 2 hours to obtain powder. This powder was tableted and solidified, pulverized, and classified by 10-20 mesh to obtain a catalyst (B5).

Preparation B6
A catalyst (B6) (CVD, chemical vapor deposition) was obtained in the same manner as in Preparation Example B5, except that the standing time was changed to 30 minutes.

Preparation B7
A catalyst (B7) was obtained in the same manner as in Preparation Example B5, except that the standing time was changed to 60 minutes.

Preparation B8
A catalyst (B8) was obtained in the same manner as in Preparation Example B5, except that the standing time was set to 180 minutes.

Preparation B9
A catalyst (B9) was obtained in the same manner as in Preparation Example B5, except that the standing time was set to 360 minutes.

Preparation B10
A catalyst (B10) was obtained in the same manner as in Preparation Example 5, except that the standing time was set to 720 minutes.

Preparation B11
1.3 g of magnesium chloride hexahydrate and 0.08 g of benzoic acid were added to 40 mL of ion-exchanged water and stirred until dissolved. 13 mL of 2.0 M NaOH was added to the resulting solution and stirred until the solution became homogeneous. The homogenized solution was transferred to a 100 mL pressure vessel, sealed, and then heated at 175° C. for 24 hours. The gel that formed in the pressure vessel was collected by filtration and dried at 100° C. overnight to give a white solid. This solid was pulverized and fired at 500° C. for 2 hours to obtain magnesium oxide crystals. This powder was tableted and solidified, crushed, and classified by 10-20 mesh to obtain catalyst (B11) (BA, benzoic acid). The specific surface area of this magnesium oxide (B11) is 165 m ² /g.

Preparation B12
Catalyst (B12) was obtained in the same manner as in Preparation Example (B6) except that catalyst (B11) was used instead of catalyst (B1).

Preparation B13
Catalyst (B13) was obtained in the same manner as in Preparation Example (B8) except that catalyst (B11) was used instead of catalyst (B1).

Preparation B14
1.0 g of catalyst (1) and 10 cc of ion-exchanged water are placed in a 50-mL round-bottomed flask and heated under reflux for 1 hour, after which the formed gel is collected by filtration and dried at 100° C. overnight to obtain a white solid. Obtained. This solid was pulverized and fired at 500° C. for 2 hours to obtain magnesium oxide crystals. This powder was tableted, solidified, crushed, and classified by 10-20 mesh to obtain a catalyst (B14) (HYD, hydrolysis). The specific surface area of this magnesium oxide (B14) is 244 m ² /g.

Preparation B15
Catalyst (B15) was obtained in the same manner as in Preparation Example (B6) except that catalyst (B14) was used instead of catalyst (B1).

Preparation B16
Catalyst (B16) was obtained in the same manner as in Preparation Example (B8) except that catalyst (B14) was used instead of catalyst (B1).

Preparation B17
1.0 g of catalyst (B1) was placed in a sample holder, heated to 300° C. at 5° C./min ⁻¹ in an electric furnace, and then placed in nitrogen carrier gas at 100 mL/min ⁻¹ using a saturator to tetraethyl ortho. A gas saturated with the silicate at room temperature was passed through for 60 minutes. Thereafter, 100 mL/ ^min of nitrogen gas is passed through for 10 minutes to exhaust tetraethyl orthosilicate remaining in the gas phase, followed by heat treatment at 500°C for 2 hours in 40 mL/ ^min of nitrogen gas, followed by cooling. bottom. The obtained crystals in the sample holder were calcined at 500° C. for 2 hours to obtain powder. This powder was tableted and solidified, pulverized, and classified by 10-20 mesh to obtain a catalyst (B17).

Preparation B18
A catalyst (B18) was obtained in the same manner as in Preparation Example B17, except that the gas in which tetraethylorthosilicate was saturated at room temperature was introduced for 720 minutes.

Preparation B19
A catalyst (B19) was obtained in the same manner as in Preparation Example B17, except that the temperature at which the gas in which tetraethylorthosilicate was saturated at room temperature was introduced was 500°C.

Preparation B20
A catalyst (B20) was obtained in the same manner as in Preparation Example B19, except that the room temperature saturated steam gas containing tetraethylorthosilicate was introduced for 360 minutes.

Preparation B21
A catalyst (B21) was obtained in the same manner as in Preparation Example B19, except that the room temperature saturated steam gas containing tetraethyl orthosilicate was introduced for 2880 minutes.

Reference Examples 2-1 to 2-3, Examples 2-1 to 2-13
0.05 g of the catalyst described in Tables 2, 3, and 4 was packed in a 6 mmφ SUS reaction tube connected to a fixed-bed gas-phase continuous flow reactor (reactor), and under N ₂ flow at 100 mL / min. was heated to 500° C. in an electric furnace.
After pretreatment for 1 hour, the electric furnace temperature was kept at 400 ° C., and 2.6% ethanol + 2.6% crotonaldehyde / N ₂ gas was added at a rate of W / F = 0.01 g · min · mL ^-1 was allowed to flow through the reactor and reacted. After gas-liquid separation was performed on the gas at the outlet of the reactor, the gas was cooled in a cooler and the condensed liquid was recovered.
After a predetermined time (10 minutes) from the start of the reaction, the composition of the outlet gas from each reactor was analyzed using a gas chromatograph and a Karl Fischer moisture meter.
Tables 2, 3 and 4 show the conversion rate (%) (ethanol conversion rate, crotonaldehyde conversion rate, raw material total conversion rate), yield (%) based on all raw materials (butadiene yield, butadiene + acetaldehyde yield), Selectivity (%) based on all raw materials (butadiene selectivity, butadiene + acetaldehyde selectivity), yield (%) based on crotonaldehyde (butadiene yield), selectivity based on crotonaldehyde (butadiene selectivity) are shown. . In the table, "butadiene" indicates 1,3-butadiene.

Reference Example 2-4, Examples 2-14 to 2-17
0.05 g of the catalyst described in Table 5 was packed in a 6 mmφ SUS reaction tube connected to a fixed bed gas phase continuous flow reactor (reactor), and was heated in an electric furnace under N ₂ flow at 100 mL / min. Heated to 500°C.
After pretreatment for 1 hour, the electric furnace temperature was kept at 400 ° C., and 3.4% ethanol + 1.7% crotonaldehyde / N ₂ gas was added at a rate of W / F = 0.01 g · min · mL ^-1 was allowed to flow through the reactor and reacted. After gas-liquid separation was performed on the gas at the outlet of the reactor, the gas was cooled in a cooler and the condensed liquid was recovered.
After a predetermined time (10 minutes) from the start of the reaction, the composition of the outlet gas from each reactor was analyzed using a gas chromatograph and a Karl Fischer moisture meter.

In some cases, the yield and selectivity based on crotonaldehyde exceed 100%. This is considered to be due to the presence of 1,3-butadiene produced directly from the raw material ethal.

As shown in Table 2, the catalysts in which SiO ₂ was supported on magnesium oxide (Examples 2-1 to 2-3, 2-6) were the same as those in magnesium oxide not supporting SiO ₂ (Reference Example 2-1 ) showed high butadiene yield and butadiene selectivity.
In addition, as shown in Tables 3 and 5, the catalysts subjected to CVD treatment (Examples 2-4 to 2-9, 2-14 to 2-17) were not subjected to CVD treatment (Reference Example 2- 1, 2-4) showed high butadiene yield and butadiene selectivity.
Furthermore, as shown in Table 4, a catalyst having a larger specific surface area of magnesium oxide tended to exhibit a higher yield of butadiene.
Further, as shown in Table 5, the catalysts subjected to CVD treatment at high temperatures (Examples 2-16 and 2-17) were the catalysts subjected to CVD treatment at low temperatures (Examples 2-14 and 2-15). It showed high butadiene yield and butadiene selectivity with less treatment time.

Claims (9)

A method for producing 1,3-butadiene, wherein 1,3-butadiene is obtained by bringing a raw material containing ethanol and crotonaldehyde into contact with a catalyst under heating, wherein the catalyst has (i) an octahedral magnesium layer on the surface is exposed, or (ii ) magnesium oxide is exposed to organosilicon compound vapor at the vapor pressure, then calcined and pulverized , and magnesium oxide is a monolayer of silica. A method for producing 1,3-butadiene, which is a supported catalyst in which silica is supported on magnesium oxide and has a covered structure. The (i) composite oxide catalyst having an octahedral magnesium layer exposed on the surface is obtained by (i-1) hydrothermally synthesized silica-magnesia or a Si—Mg composite oxide having a talc structure treated with an alkali. or (i-2) serpentine. 3. The method for producing 1,3-butadiene according to claim 2, wherein the hydrothermal silica-magnesia is prepared by heating an acidic aqueous solution containing a magnesium compound and a silicon compound together with urea under pressure. 4. The method for producing 1,3-butadiene according to claim 2 or 3, wherein the hydrothermally synthesized silica-magnesia contains a metal or metalloid element other than magnesium and silicon. 5. The production of 1,3-butadiene according to claim 4, wherein said metal or metalloid element other than magnesium and silicon is at least one selected from the group consisting of cobalt, nickel, copper, zinc, gallium, silver and indium. Method. 6. The method for producing 1,3-butadiene according to claim 4 or 5, wherein the total content of the metals or metalloid elements other than magnesium and silicon is 0.1 to 5% by weight based on the total weight of the catalyst. 3. The method for producing 1,3-butadiene according to claim 2, wherein the Si--Mg composite oxide having a talc structure is talc or natural sepiolite. The method for producing 1,3-butadiene according to any one of claims 2 to 7, wherein the alkali treatment is treatment with an aqueous potassium hydroxide solution. In the (i) composite oxide catalyst having an octahedral magnesium layer exposed on the surface, the element ratio of magnesium and silicon (molar ratio: Mg/Si) is 0.7 to 2.0. 1. The method for producing 1,3-butadiene according to any one of the items.

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