JPH0748299A - Production of ethanol - Google Patents

Abstract

PURPOSE:To produce ethanol by hydrogenating carbon dioxide in a liquid phase in the presence of a catalyst. CONSTITUTION:This method for producing ethanol is characterized by hydrogenating carbon dioxide in a solvent in the presence of a ruthenium carbonyl complex, a cobalt carbonyl complex and iodine or an iodine compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing ethanol by hydrogenation of carbon dioxide gas, and more particularly to the production of carbon dioxide gas in a solvent in the presence of a ruthenium carbonyl complex, a cobalt carbonyl complex and iodine or an iodine compound. The present invention relates to a method for producing ethanol by hydrogenating.

[0002]

2. Description of the Related Art It is known that it is effective to use various metals and metal oxides as catalysts in a method for producing methanol, methane, carbon monoxide or the like by hydrogenating carbon dioxide gas (for example, for example, , Arakawa Hironori, Catalyst, 31 , 558,
1989). Also, regarding the production of ethanol and higher alcohols by hydrogenation of carbon dioxide, it is reported that it is effective to use a catalyst for methanol production modified with various metals or metal oxides as a catalyst ( For example, T. Tatsumi et al., Chem. Lett., 593, 1985). The hydrogenation reaction of carbon dioxide gas using these metal catalysts or metal oxide catalysts is a heterogeneous reaction in which the reactant (gas) and the catalyst (solid) have different phases and is accompanied by a large amount of heat generation. It is an exothermic reaction. In the case of a gas-solid heterogeneous reaction involving a large amount of heat generation, it is difficult to control the temperature of the reactor, and this method should be used especially when a large amount of the target substance is to be produced using a large reactor. Are considered difficult.

In order to solve such a problem, it is considered that in the hydrogenation reaction of carbon dioxide gas, a solution of a transition metal complex dissolved in a solvent is used as a catalyst to carry out a homogeneous reaction in a liquid phase. In fact, such reactions allow formic acid, formic acid amides, formic acid esters (eg, Darensbourg, Chemt.
ech, 636, 1985), methanol, methane and carbon monoxide (Japanese Patent Application No. 5-52272), but ethanol has not yet been obtained.

[0004]

The present invention has been made in view of the above situation, and an object thereof is to provide a method for efficiently producing ethanol by a homogeneous reaction.

[0005]

The method for producing ethanol of the present invention is characterized in that carbon dioxide gas is hydrogenated in a solvent in the presence of a ruthenium carbonyl complex, a cobalt carbonyl complex, and iodine or an iodine compound.

[0006]

In the present invention, a transition metal complex such as a ruthenium carbonyl complex and a cobalt carbonyl complex, and iodine or an iodine compound is used as a substance having a catalytic action.

The ruthenium carbonyl complex is not particularly limited, and as the ligand, halide ion, hydride ion, phosphine and the like are used other than carbon monoxide. Examples of such complexes include, for example, Ru (CO) ₅ ,
Complexes containing only carbon monoxide such as Ru ₃ (CO) ₁₂ ; complexes containing iodine such as Ru ₂ I ₄ (CO) ₁₂ ; such as Ru ₄ H ₄ (CO) ₁₂ A complex containing hydrogen; a complex containing a phosphine such as Ru (CO) ₂ (PPh ₃ ) _{3 and} the like can be mentioned, and Ru ₃ (CO) ₁₂ is preferable.

The cobalt carbonyl complex is also not particularly limited, and as the ligand, halide ions, hydride ions, phosphines and the like can be used in addition to carbon monoxide. Examples of such a complex include Co ₂ (C
O) ₈ , Co ₄ (CO) _12, etc. containing only carbon monoxide; for example HCo (CO) ₅ etc. containing hydrogen; for example Co ₂ (CO) ₆ (PPh ₃ ) Examples thereof include complexes containing phosphines such as ₂ , and Co ₂ (CO) ₈ is preferable. As the ruthenium complex and the cobalt complex, different ones may be used as described above, but the present invention also includes the case where a mixed complex of ruthenium and cobalt is used. Examples of such a complex include a complex containing carbon monoxide and hydrogen, such as Co ₃ RuH (CO) ₁₂ .

In order to increase the amount of ethanol produced, the atomic ratio of cobalt / ruthenium is preferably 0.1-10, more preferably 0.5-3, most preferably 0.9-1.1. is there. When the atomic ratio of cobalt / ruthenium is less than 0.1, the yield of ethanol becomes poor,
On the other hand, when it exceeds 10, the hydrogenation reaction of carbon dioxide does not proceed.

[0010] The iodine compound is not particularly limited, for example KI, NaI, alkali metal iodides such as LiI, e.g. CaI _2, MgI ₂ such as alkaline earth metal iodides, for example ZnI _2, CdI ₂ such as a transition metal Metal iodides such as iodides; oxides such as HIO, HIO ₃ ;
For example, interhalogen compounds such as ICl and IBr are used, preferably KI, NaI and LiI are used, and more preferably NaI is used. These iodine and iodine compounds may be used alone or in combination of two or more.

The atomic ratio of iodine or iodine compound / ruthenium is preferably 1 to 50, more preferably 5 to 10. On the other hand, the atomic ratio of iodine or iodine compound / cobalt is preferably 1 to 50, and more preferably 5 to 10. If these ratios are less than the above range, the reaction rate decreases because ruthenium or cobalt precipitates as a metal, while if it exceeds the above range, the amount of by-products such as methane instead of ethanol increases, which is not preferable. .

These catalysts may be dissolved in a solvent in advance in a ratio within the above range outside the reaction system and then added to the reaction system, but the catalyst and the solvent may be directly supplied to the reaction vessel to obtain a uniform mixture. The liquid phase reaction catalyst is more convenient in operation.

Examples of the solvent used in the present invention include N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP) and 1,3-dimethylimidazolidinone (D
Examples thereof include polar aprotic solvents such as MI) and tetramethylurea (TMU), and preferably DMI.

The concentration of the ruthenium carbonyl complex and the cobalt carbonyl complex is preferably 1 to 1 L of the solvent.
100 mmol, more preferably 5 to 25 mmo
It is l. If it is less than 1 mmol / L, the reaction is difficult to proceed, while if it exceeds 100 mmol / L, it is difficult to dissolve in the solvent, which is not preferable.

The concentration of iodine and iodine compound is preferably 100 to 2000 mmol per 1 L of the solvent.
These have an action of preventing the above transition metal complex from decomposing and depositing ruthenium and cobalt as metal.
When these metals are deposited, the reaction proceeds as a heterogeneous catalytic reaction, a large amount of methane is produced as a by-product, and an exothermic reaction proceeds to make temperature control of the reactor difficult. This is not preferable because it causes problems.

According to the method of the present invention, the ruthenium carbonyl complex, the cobalt carbonyl complex and the catalyst of iodine or an iodine compound are dissolved in a polar aprotic solvent such as N-methylpyrrolidone and the mixture is pressurized with carbon dioxide gas and hydrogen. Ethanol is produced by heating at.

Volume ratio of carbon dioxide and hydrogen (CO ₂ / H ₂ )
Is preferably 0.1 to 1. When the volume ratio is less than 0.1, the ruthenium carbonyl complex and the cobalt carbonyl complex are easily decomposed to precipitate metal ruthenium and metal cobalt, while the volume ratio is 1 or less. If it exceeds the limit, the reaction rate will decrease and it is not recommended. The total pressure of carbon dioxide gas and hydrogen during the reaction is preferably 1 to 1000 atm,
The pressure is more preferably 50 to 300 atm. Reaction temperature is 1
The temperature is preferably 50 to 300 ° C, more preferably 170 to 210 ° C. If the temperature is lower than 150 ° C., the reaction is difficult to proceed, whereas if the temperature exceeds 300 ° C., the ruthenium carbonyl complex and the cobalt carbonyl complex are decomposed to deposit metal ruthenium and metal cobalt, which is not preferable.

In a preferred embodiment, the above reaction is carried out in the presence of methanol. In the present invention, methanol acts as a reaction intermediate and is used in the conversion reaction into ethanol, and as a result, it is expected that the amount of ethanol produced will increase. The concentration of methanol used in the present invention is 1 mol /
It is preferably L. Hereinafter, the present invention will be described in more detail with reference to Examples, but this is for the purpose of showing representative exemplification, and is not intended to limit the present invention.

[0019]

【Example】

(Examples 1 to 7) In Examples 1 to 6, in a 100 mL autoclave, a solvent (20 mL), a predetermined amount of Ru ₃ (CO) ₁₂ , and Co ₂ (CO) ₈ shown in Table 1 (these are either Is also expressed as mmol number of Ru and Co), iodine (5 mmol) or iodine compound (10 mmol)
After charging carbon dioxide gas at 20 atm and hydrogen gas at 100 atm at room temperature, the reaction was carried out at 30 ° C. for 15 hours. NMP or DMI was used as a solvent. In Example 7, after adding methanol (20 mmol) in advance, the same reaction as in Example 2 was performed. In addition, in Examples 1 to 7,
The total amount of ruthenium and cobalt in the complex is 0.12
It was kept constant at mmol. The products obtained by these reactions were quantitatively analyzed by gas chromatography.
The results are shown in Table 1.

[0020]

[Table 1]

In each of the examples, it was confirmed that the ruthenium complex and cobalt complex were not decomposed into metal, and the reaction proceeded in a uniform liquid phase. Further, it has been found that the following conditions are preferable to increase the production amount of ethanol.

1) Regarding the atomic ratio of cobalt / ruthenium: When Examples 1, 2 and 3 are compared, the amount of ethanol produced increases as the atomic ratio of cobalt / ruthenium increases from 0.5 to 1 (Examples). However, when the atomic ratio of cobalt / ruthenium is increased from 1 to 2, the amount of ethanol produced is decreased (Examples 2 to 3). From this, it is understood that when the cobalt / ruthenium atomic ratio is close to 1, the amount of ethanol produced is the largest.

2) Regarding the type of iodine or iodine compound: The effect of iodine or iodine compound when the atomic ratio of cobalt / ruthenium is set to 1 is shown in Example 2,
As is clear from comparison between 4 and 5, the amount of ethanol produced is increased when sodium iodide is used rather than potassium iodide or iodine.

3) Solvent: The effect of the solvent used when the atomic ratio of cobalt / ruthenium was set to 1 becomes clear by comparing Examples 2 and 6. That is,
It can be seen that the amount of ethanol produced increases when DMI is used as the solvent rather than NMP.

4) Coexistence of methanol: Example 2
Comparing Example 7 with Example 7, it can be seen that in the presence of methanol, the production amount of ethanol is approximately doubled, and the production amount of ethanol is increased.

[0026]

INDUSTRIAL APPLICABILITY In the present invention, since the ruthenium carbonyl complex, the cobalt carbonyl complex and iodine or an iodine compound are used by dissolving them in a solvent, the hydrogenation reaction of carbon dioxide gas is uniformly carried out in the liquid phase. Therefore, the temperature of the reactor can be controlled more easily than in the case of the conventional heterogeneous catalytic reaction using a metal catalyst or a metal oxide catalyst, and ethanol can be efficiently produced. Further, it is possible to further increase the production amount of ethanol by selecting a solvent, iodine or an iodine compound used in the reaction and coexisting with methanol.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 000000284 Osaka Gas Co., Ltd. 4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka (71) Applicant 000000974 Kawasaki Heavy Industries, Ltd. 3 Higashi-Kawasaki-cho, Chuo-ku, Kobe-shi, Hyogo 1-1-1 (71) Applicant 000156961 Kansai Thermochemical Co., Ltd. 2-23 Ohama-cho, Amagasaki-shi, Hyogo (71) Applicant 000003126 Mitsui Toatsu Chemical Co., Ltd. 3-5-2 Kasumigaseki, Chiyoda-ku, Tokyo ( 71) Applicant 000183303 Sumitomo Metal Mining Co., Ltd. 5-11-3 Shimbashi, Minato-ku, Tokyo (74) Attorney-at-law attorney Kuichi Ueki (72) Inventor Kenichi Tominaga 16-3 Onogawa, Tsukuba, Ibaraki Resource and Environmental Technology Research Laboratory (72) Inventor Masahiro Saito 16-3 Onogawa, Tsukuba, Ibaraki Prefecture Resource and Environmental Technology Research Laboratory (72) Inventor Sasaki Yoshiyuki 16-3 Onogawa, Tsukuba-shi, Ibaraki (72) Inventor Daiki Watanabe 2-8-11 Nishishimbashi, Nishishinbashi, Minato-ku, Tokyo 7th Toyo Kaiji Building 8F Research Institute for Global Environmental Technology Organization CO2 Immobilization Project Room (72) Inventor Masami Takeuchi 2-8-11 Nishi-Shimbashi, Minato-ku, Tokyo 7th Toyo Kaijuku Building 8F Research Institute for Global Environmental Technology CO2 Immobilization Project Room (72) Inventor Terumitsu Kakumoto 2-8-11 Nishi-Shimbashi, Minato-ku, Tokyo 7th Toyo Kaiji Building 8F Research Institute for Global Environmental Science and Technology, CO2 immobilization project room (72) Inventor Yuki Kanai Nishi, Minato-ku, Tokyo 2-8-11 Shimbashi 7th Tokai Kaijuku Building 8F Research Institute for Global Environment and Industrial Technology CO2 fixation project room (72) Inventor Keiko Moriya 2-8-11 Nishishinbashi, Minato-ku, Tokyo 7th Tokai Building 8F Global Environmental Industrial Technology Research Institute CO2 Immobilization Project Room (72) Inventor Konosuke Hagiwara 2-8-11 Nishi-Shimbashi, Minato-ku, Tokyo 7th Toyo Kaiji Building 8F Institute for Global Environmental Technology Research CO2 Immobilization Project Room

Claims (4)

[Claims] 1. A method for producing ethanol, which comprises hydrogenating carbon dioxide in a solvent in the presence of a ruthenium carbonyl complex, a cobalt carbonyl complex, and iodine or an iodine compound. 2. The method according to claim 1, which is carried out in the presence of methanol.
The method described in. 3. The iodine compound is at least one selected from the group consisting of alkali metal iodides, alkaline earth metal iodides, and transition metal iodides.
Or the method described in 2. 4. The solvent is N-methylpyrrolidone, N-
The method according to claim 1, which is ethylpyrrolidone or 1,3-dimethylimidazolidinone.