JPS6361293B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for directly producing ethanol from carbon monoxide and hydrogen (hereinafter referred to as synthesis gas). More specifically, the present invention relates to a selective production method for directly synthesizing ethanol from synthesis gas by a liquid phase catalytic reaction using ruthenium compounds, cobalt compounds and halogen compounds as catalysts. Ethanol is a compound that has a wide range of uses as an intermediate raw material or solvent for various chemicals. (Prior Art) A method for producing methanol and/or ethanol using carbon monoxide and hydrogen as raw materials in the presence of a ruthenium-containing catalyst is known. for example,
A method for directly producing methanol, ethylene glycol and ethanol or their carboxylate derivatives by reacting hydrogen and carbon monoxide in a suitable solvent containing a solubilized ruthenium carbonyl complex (Japanese Patent Application Laid-Open No. 115834/1983); In addition, a method for producing acetaldehyde and/or ethanol by reacting carbon monoxide with a ruthenium source and a halide source in the presence of a catalyst system (Japanese Patent Application Laid-open No.
56-166133), and a method for selectively producing methanol and ethanol by contacting a homogeneous ruthenium catalyst, a halogen or halide promoter, and an organic oxidized phosphine compound with carbon monoxide and hydrogen (Japanese Patent Application Laid-open No. 57-82327). ), etc. In a catalytic reaction using such a ruthenium compound, methane is produced as a byproduct in addition to ethanol. Many patent applications relating to the reaction of carbon monoxide and hydrogen catalyzed by ruthenium compounds have no mention of methane production. However, as long as the present inventors carried out known techniques, a large amount of methane was detected compared to the amount of ethanol produced. Generally, the amount of methane produced tends to increase when the reaction temperature is high or when a large amount of hydrogen halide or alkyl halide is used as a promoter. Furthermore, when the activity of ethanol was high, the yield of methane increased accordingly. This by-product methane is discarded in the industrial process along with a portion of the unreacted synthesis gas.
This process reduces the utilization rate of synthesis gas and greatly impairs the economics of the process. Therefore, in order to industrialize the method of producing ethanol from synthesis gas, it is necessary to suppress the by-product of methane as much as possible. On the other hand, catalytic reactions using ruthenium compounds and cobalt compounds are characterized by very little methane by-product, but the main product is acetic acid, and the selectivity for ethanol is low (Japanese Patent Application Laid-open No.
67641). As described above, the known techniques are not sufficient in terms of ethanol selectivity for industrialization. (Problems to be Solved by the Invention) An object of the present invention is to solve the problem of methane by-product production in the conventional technology of producing ethanol from synthesis gas, and to provide an economical method for selectively producing ethanol. be. (Means for Solving the Problems) The present inventors have made extensive studies to solve these problems. As a result, acetic acid and We have discovered a method for selectively producing ethanol while keeping the amount of methane as a by-product small by supplying an ester of acetic acid to the reaction system, thereby reducing the net production amount of acetic acid, and the present invention It came to this. That is, the present invention provides a method for selectively producing ethanol by contacting a catalyst containing a ruthenium compound, a cobalt compound, and a halogen compound as main components with carbon monoxide and hydrogen under high temperature and high pressure. So 1:
The ratio should be in the range of 0.3 to 1:10. The reaction should be carried out in a phosphine oxide solvent. This is a selective ethanol production method characterized by supplying acetic acid and/or esters of acetic acid to the reaction system. The ruthenium compound and cobalt compound used in the method of the present invention may be any compound that produces a ruthenium complex having a carbon monoxide ligand under the reaction conditions. Examples of ruthenium compounds include metal ruthenium, ruthenium oxides such as ruthenium dioxide and ruthenium tetroxide, their hydrates, and mineral acid salts of ruthenium such as ruthenium chloride, ruthenium iodide, and ruthenium nitrate. , organic acid salts of ruthenium such as ruthenium acetate and ruthenium propionate. Ruthenium compounds can also be used directly in the form of coordination compounds, examples of which include ruthenium carbonyl, such as triruthenium dodecacarbonyl, and ruthenium combined with oxygen, sulfur, halogens, nitrogen, phosphorous, arsenic, etc. , antimony,
Examples include ruthenium complexes coordinated with ligands such as bismuth, and their salts. Among these ruthenium compounds, ruthenium oxide, ruthenium halide, ruthenium carbonyl, ruthenium acetylacetonate,
Alternatively, a ruthenium complex in which at least some of the carbon monoxide ligands of ruthenium carbol are replaced with other ligands is preferable. In addition to metal cobalt, cobalt compounds include cobalt oxide, cobalt hydroxide, cobalt mineral salts such as cobalt chloride, cobalt iodide, and cobalt nitrate, cobalt acetate, cobalt benzoate, and cobalt naphthenate. There are organic acid salts of cobalt. In addition, coordination compounds can also be used, such as cobalt carbonyl, such as dicobalt octacarbonyl, tetracobalt dodecacarbonyl, cyclopentanedienyl cobalt dicarbonyl, and cobalt with oxygen. Examples include cobalt complexes coordinated with ligands containing sulfur, halogen, nitrogen, phosphorus, arsenic, antimony, bismuth, etc., and their salts. Among these cobalt compounds, at least some of the carbon monoxide ligands of cobalt oxide, cobalt halide, cobalt carbonyl, cobalt organic acid salt, cobalt acetylacetonate, or cobalt carbonyl are replaced with other ligands. Cobalt complexes and the like are preferred. The amount of the ruthenium compound used in the method of the present invention in the liquid medium is 0.1 to 300 parts by weight of the liquid medium in terms of ruthenium metal.
Parts by weight range. The amount of the cobalt compound to be used is in the range of 1:0.1 to 1:100, preferably 1:0.3 to 1:10, as an atomic ratio of ruthenium to cobalt. Further, in the method of the present invention, it is necessary to use a halogen compound as a promoter for the ruthenium compound and the cobalt compound. In the absence of these halogen compounds, ethanol activity and selectivity are significantly lower. These halogen compounds include metal salts such as alkali metal salts and alkaline earth metal salts having halogen ions such as chloride ions, bromide ions, and iodine ions as anions constituting the salts;
Examples include salts such as ammonium salts, quaternary phosphonium salts, and iminium salts, and hydrocarbon halides such as alkyl halides and aryl halides. Further, hydrogen halides, acid halides, transition metal halides, and the like can also be used. More specifically, examples of metal salts include lithium chloride, lithium bromide, lithium iodide, sodium chloride, potassium bromide, cesium iodide, magnesium chloride, lanthanum iodide, etc.
Examples of ammonium salts include trimethylammonium chloride, trimethylammonium bromide, trimethylammonium iodide,
Examples of quaternary phosphonium salts include dimethylethylammonium chloride, methyldiethylammonium iodide, tetramethylammonium chloride, tetramethylammonium iodide, tetraphenyl ammonium chloride, and cetyltriethylammonium bromide. n-butylphosphonium bromide, n-heptyltriphenylphosphonium bromide, benzyltriphenylphosphonium iodide,
Examples of iminium salts such as methyltriphenylphosphonium chloride include bis(triphenylphosphine)iminium chloride, bis(triphenylphosphine)iminium bromide, bis(triphenylphosphine)iminium iodide, and these iminium salts. Examples of alkyl halides include iminium salts in which at least a portion of the phenyl group of the compound is substituted with a methyl group or ethyl group, and examples of alkyl halides include methyl chloride, methylene chloride, chloroform, carbon tetrachloride, methyl iodide, ethyl iodide, benzyl chloride, benzyl iodide, etc.
Examples of hydrogen halides are hydrogen chloride, hydrogen bromide,
Examples of acid halides include acetyl chloride and acetyl bromide. Examples of transition metal halides include nickel chloride, ruthenium chloride, and copper iodide. Moreover, iodine, chlorine gas, and bromine gas can also be used. These halogen compounds can be used alone or in combination of two or more. In the method of the present invention, the amount of these halogen compounds used per gram atom of ruthenium is:
The halogen atoms range from 0.1 to 200 gram atoms, more preferably from 1 to 20 gram atoms. The method of the invention can be carried out in a liquid medium. The liquid medium used is preferably an aprotic liquid solvent. For example, saturated and aromatic hydrocarbons such as heptane, octane, cyclohexane, decalin, tetralin, kerosene, benzene, toluene, xylene, diylene, hexamethylbenzene,
Halogenated hydrocarbons such as chloropentane, o-dichlorobenzene, p-chlorotoluene, fluorobenzene, dioxane, tetrahydrofuran,
Ethers such as ethyl ether, anisole, phenyl ether, diglyme, tetraglyme, and 18-crown-6, esters such as methyl acetate, ethyl butyrate, methyl benzoate, and γ-butyrolactone, and ketones such as acetone, acetophenone, and benzophenone. N-methylpyrrolidin-2-one, N-ethylpyrrolidin-2-one,
N-substituted amides such as N,N-dimethylacetamide, N-methylpiperidone, and hexamethylphosphoric triamide, tertiary amines such as N,N-diethylaniline, N-methylmorpholine, pyridine, and quinoline, and sulfolane. Examples include sulfones, sulfoxides such as dimethylsulfoxide, urea derivatives such as 1,3-dimethyl-2-imidazolidinone, phosphine oxides such as tributylphosphine oxide, and silicone oil. . Among these, phosphine oxides are particularly preferred liquid solvents. These liquid solvents can be used alone or in combination of two or more. Further, if the liquid solvent used in the method of the present invention is liquid at least under the reaction conditions,
It can be used even if it is solid at room temperature and pressure. In the method of the present invention, acetic acid and/or
Or supply acetate ester. Forms of acetic acid include, in addition to acetic acid, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, and the like. It is also possible to use acetates such as ammonium acetate, calcium acetate, cobalt acetate, and the like. Among these compounds, acetic acid and methyl acetate are particularly preferred. These compounds can be used alone or in combination of two or more. The supply of acetic acid, acetate ester, and/or acetate to the reaction system is such that the net production amount of acetic acid is 0.
It is preferable to do so. Such a supply is advantageous in industrial processes where the recovered acetic acid and acetate are recycled back to the reactor. As the amount supplied to the reaction system increases, the net amount of acetic acid produced decreases, and the amount supplied is adjusted so that it becomes zero. However, if too large a quantity is supplied, the activity of the catalyst will decrease, which is not preferable. Here, the net amount of acetic acid produced is calculated from the total amount of acetic acid after the reaction and the amount of acetic acid esters converted to acetic acid, the amount of acetic acid supplied, and when using acetate esters or acetates, , excluding the total amount converted into acetic acid. The range of molar ratios of carbon monoxide and hydrogen used as synthetic raw materials in the method of the present invention is usually
The ratio is 1:10 to 10:1, preferably 1:3 to 2:1. It is also possible to use other inert components such as methane and nitrogen in the synthesis gas. In the method of the present invention, the reaction temperature is in the range of 160 to 300°C, preferably in the range of 180 to 260°C. At reaction temperatures below 160°C, the reaction between carbon monoxide and hydrogen is extremely slow. Also, if the reaction temperature exceeds 300℃,
Methane by-product increases significantly and ethanol selectivity decreases. Further, the reaction pressure is in the range of 150 to 800 Kg/cm ² , preferably in the range of 300 to 500 Kg/cm ² . The higher the reaction pressure is, the more preferable it is for the reaction of carbon monoxide and hydrogen, but the practical pressure is preferably 800 Kg/cm ² or less. The method of the present invention can be carried out in a batch, semi-continuous or continuous manner. In the method of the invention, acetic acid and/or
Alternatively, the esters of acetic acid may be initially added to the reactor in batch mode or may be fed semi-continuously or continuously. (Function) In the present invention, in a method for producing ethanol by bringing a raw material synthesis gas into contact with a catalyst containing a ruthenium compound and a cobalt compound, a binary system of ruthenium and cobalt in which the atomic ratio of ruthenium and cobalt is within a specific range is used. By using phosphine oxides as a solvent and supplying acetic acid and/or esters of acetic acid to the reaction system in the presence of a catalyst, the net amount of acetic acid produced is reduced, and the The proportion of ethanol can be relatively increased. According to this method, the selectivity of ethanol is improved while suppressing the amount of methane by-product, which is an advantage of ruthenium and cobalt catalysts. Industrially, the amount of waste material synthesis gas can be reduced compared to conventional methods. That is, the method of the present invention improves C ₁ chemistry technology to an industrial level compared to conventional methods. (Example) Hereinafter, the method of the present invention will be explained in more detail with reference to Examples and Comparative Examples. Example 1 In a stainless steel autoclave with a capacity of 50ml
0.28 mg atoms of triruthenium dodecacarbonyl [Ru ₃ (CO) ₁₂ ], 0.84 mg atoms of dicobalt octacarbonyl [CO ₂ (CO) ₈ ], 3.5 mmoles of bis(triphenylphosphine)iminium chloride [(φ ₃ p) ₂ NCl], 0.84 mmole of phosphoric acid, 2 g of acetic acid, and 10 g of tri-n-butylphosphine oxide (Bu ₃ po), and the synthesis gas (CO:H ₂ molar ratio 1:1) was heated to room temperature. It was press-fitted to 340Kg/ ^cm2 . The autoclave was heated with stirring to maintain the internal temperature at 240°C to carry out the reaction. During this time, the internal pressure of the autoclave changed from 460 to 350 Kg/ ^cm2 . Next, the heating of the autoclave was stopped, and after cooling to room temperature, the pressure was released, and the contents were taken out and analyzed by gas chromatography. The results are shown in Table 1. Examples 2 to 7 In the method of Example 1, the amount of acetic acid added and
The molar ratio of CO and _H2 was changed. The results are shown in Example 1.
They are shown in Table 1. Comparative Examples 1 to 4 Table 1 shows the results obtained by not adding acetic acid or a cobalt compound and acetic acid in the method of Example 1.

[Table] Examples 8-10, 12-18, 22-23 and Comparative Examples 5-
6, 9-12, 15-16 The ruthenium compound concentration, cobalt compound concentration, amount of acetic acid or methyl acetate supplied, type of halogen compound, type of additive, type of solvent, and reaction temperature were determined in the same manner as in Example 1. The reaction was carried out with changes as shown in Tables 2 to 4. These results are shown in Tables 2 to 4.
Shown below.

【table】

【table】

【table】

[Table] In Tables 1 to 4, each symbol represents the following compound. 1) Each symbol represents the following compound. Ru: Triruthenium dodecacarbonyl Co: Dicobalt octacarbonyl PPNCl: Bis(triphenylphosphine)iminium chloride PPNBr: Bis(triphenylphosphine)iminium bromide LiCl: Lithium chloride LiBr: Lithium bromide H ₃ PO ₄ : Phosphorus Acid Bu ₃ PO: Tri-n-butylphosphine oxide Pr ₃ PO: Tri-n-propylphosphine oxide 2) MeOH shown in the product (mmol) column,
EtOH and AcOH are values obtained by converting the generated ester into the corresponding methanol, ethanol, and acetic acid and adding them. 3) AcOH is the net production amount. (Effect) Comparative Example 2 in Table 1 is a result in which no cobalt compound was used, but the proportion of methane was as high as 29.8%. As a result, the percentage of ethanol was 20.9%. Comparative Example 1 is the result of using a catalyst containing a ruthenium compound and a cobalt compound. The proportion of methane is small at 9.5%, but the proportion of acetic acid is large at 45.9%.
As a result, the percentage of ethanol remains at 24.1%. On the other hand, Examples 1 to 3 are the results of adding acetic acid. It is shown that as the amount of acetic acid added increased, both the proportions of acetic acid and methane decreased. In Example 3, the net amount of acetic acid produced was zero. The percentage of methane at this time was 2.4%,
This was suppressed to 1/10 or less compared to Comparative Example 2, which did not use a cobalt compound. As a result, the proportion of ethanol is
This improved to 35.7%. Examples 4 and 5 are CO:H ₂ (molar ratio) 1:1.3
Even under these conditions, a decrease in the net amount of acetic acid produced was observed by supplying acetic acid, and in Example 5 it was almost zero. The proportion of methane at this time is
It has been suppressed to 5.9%. Examples 6 and 7 were CO:H ₂ (molar ratio) 1:2.5
These are the results under the following conditions. The net production of acetic acid is also reduced in these examples. Although the proportion of methane at this time is increased compared to Comparative Example 4, the amount of methane by-product is greatly suppressed compared to when no cobalt compound is used (for example, Comparative Example 2). In Examples 8-10, 12-18, and 22-23, the same effects as described above were confirmed compared to the corresponding Comparative Examples 5-6, 9-12, and 15-16. As described above, by using the method of the present invention, the proportion of ethanol can be increased while suppressing the amount of methane by-product.

Claims (1)

[Claims] 1. A method for selectively producing ethanol by contacting a catalyst containing a ruthenium compound, a cobalt compound, and a halogen compound as main components with carbon monoxide and hydrogen at high temperature and high pressure, The ratio of atomic ratio is 1:
A method for selectively producing ethanol, characterized in that the ratio is in the range of 0.3 to 1:10; the reaction is carried out in a phosphine oxide solvent; and acetic acid and/or esters of acetic acid are supplied to the reaction system.