JPS6121930B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for directly producing oxygen-containing compounds such as acetic acid, ethanol, methanol, and their esters from a mixed gas of carbon monoxide and hydrogen (hereinafter referred to as synthesis gas), and in particular to a method for producing oxygen-containing compounds such as acetic acid, ethanol, methanol, and their esters. The present invention relates to a selective manufacturing method. Acetic acid, ethyl acetate, methyl acetate, etc. are substances that are industrially useful as industrial chemicals and solvents, and this is an attempt to develop a method to directly produce these oxygenated compounds using synthesis gas as a raw material (so-called direct method). is being done. Recently, a method for producing oxygen-containing compounds by a liquid phase direct method using ruthenium has been disclosed. The target products of these known techniques are often carbon-2 oxygenated compounds such as ethylene glycol, ethanol, and acetaldehyde, but a method for selectively producing any of these target products has not yet been perfected. Furthermore, it is known that significant amounts of other by-products such as methanol are produced. As methods for producing such oxygen-containing compounds, there are, for example, methods disclosed in JP-A-55-9088 and JP-A-55-104217. That is, it is a method for producing alcohols as esters with a carboxylic acid solvent by using a catalyst made of ruthenium and/or osmium in a liquid medium containing a carboxylic acid, and further, by thermal decomposition of the produced ethyl ester. Discloses a method for producing ethylene by. Also, JP-A No. 57-123128, No. 58-921,
No. 58-922 and No. 58-8026 disclose a method for producing alcohol using a ruthenium-based binary catalyst containing ruthenium and other transition metals. In these methods, low melting point quaternary phosphonium salts are effectively used as cocatalysts and liquid media. Among these, the method disclosed in JP-A-58-8026 is a method for producing alcohol, especially ethanol, using a ruthenium-cobalt catalyst system, but it is known that a small amount of acetate ester is produced. However, problems with this method for producing acetic acid include low acetic acid synthesis activity and low selectivity, and a large amount of methane produced, which is an undesirable by-product. Also, JP-A-55-115834 and JP-A No. 56-
The method disclosed in Publication No. 166133 is a method for producing alcohol and acetaldehyde using a ruthenium catalyst, and preferably uses a halogen salt as a co-catalyst and an ether or an aprotic organic amide as a solvent. Further, in JP-A-57-82327, organic phosphine oxide is used as an effective liquid medium, but this is a method for producing alcohol, especially ethanol, and there is no description regarding the production of acetic acid. As described above, even with these methods, both synthetic activity and selectivity are still insufficient as industrial methods for producing acetic acid and acetic esters. There is a strong desire to develop acetic acid and acetate esters that improve the shortcomings of known techniques, and the present inventors have already developed a method for selectively producing acetic acid (including esters) by a direct liquid phase method. ,
He applied for his life (Special Application No. 163447, 1982). Among them, he disclosed that the presence of a base is necessary for acetic acid synthesis using a ruthenium-cobalt catalyst system, and that a wide variety of basic substances are effective. Furthermore, as a result of intensive research into improving the ruthenium-cobalt catalyst system, the present inventors found that organic phosphine oxide is particularly effective as a base and a liquid medium.
The present invention was completed by discovering that by using this, acetic acid and acetic ester can be efficiently and selectively produced. That is, the present invention is characterized in that when reacting synthesis gas under heat and pressure in a liquid medium containing a ruthenium compound, a cobalt compound, and a halogen-containing promoter, the reaction is carried out in the presence of an organic phosphine oxide. The present invention relates to a method for selectively producing acetic acid and acetic ester. Esters such as methyl acetate and ethyl acetate obtained by the method of the present invention are themselves useful as industrial chemicals and solvents, but if necessary, they can be easily hydrolyzed and converted to carboxylic acids and alcohols. . Therefore, unless otherwise specified, each carboxylic acid, including the carboxylic acid and alcohol contained in the ester, such as acetic acid,
and alcohols such as ethanol. The organic phosphine oxide used in the method of the invention has the general formula R ₃ P=0, where R represents an unsubstituted or substituted alkyl group or aryl group having 1 to 20 carbon atoms. will be shown. The organic phosphine oxide has the role of liquid medium (reaction solvent) and base which advantageously allows the formation of acetic acid, among the products of the process according to the invention. That is, the characteristic effect of organic phosphine oxide is to increase the production rate of acetic acid and the production molar ratio of (acetic acid)/(ethanol). Examples of such organic phosphine oxides include:
Examples include: Namely, trimethylphosphine oxide, triethylphosphine oxide, tripropylphosphine oxide, tributylphosphine oxide, trihexylphosphine oxide, trioctylphosphine oxide, tricyclohexylphosphine oxide, triphenylphosphine oxide, ethyldiphenyl. phosphine oxide, i
-propyldiphenylphosphine oxide, tri(p-methoxyphenyl)phosphine oxide, tri(2-methoxyethyl)phosphine oxide, and the like. The amount of organic phosphine oxide used is 0.1 to 100% by weight based on the total weight of the liquid medium (i.e., organic phosphine oxide or a mixture of organic phosphine oxide and other solvents) used in the reaction;
Preferably it is 5 to 100% by weight. The ruthenium compound and cobalt compound used in the method of the present invention may be any compound that can produce soluble ruthenium complexes and cobalt complexes having carbon monoxide as a ligand under the reaction conditions, and are generally known in the art. Known compounds can be used. Examples of ruthenium compounds include, in addition to metal ruthenium, ruthenium oxides and their hydrates such as ruthenium dioxide and ruthenium tetroxide, ruthenium mineral acid salts such as ruthenium chloride, ruthenium iodide, ruthenium nitrate, and acetic acid. Ruthenium, organic acid salts of ruthenium such as ruthenium propionate, ruthenium pentacarbonyl, Ru ₃ (CO) ₁₂ , [Ru
Ruthenium carbonyl complexes such as (CO) ₃ Cl ₂ ] ₂ ,
Further examples include ruthenocene, ruthenium acetylacetonate, and ruthenium complexes in which ruthenium is coordinated with various ligands. Among these ruthenium compounds, ruthenium oxides and hydrates thereof, ruthenium halides, ruthenium carbonyl complexes, and ruthenium complexes having other ligands are preferred. Examples of cobalt compounds include metal cobalt, cobalt oxide, cobalt hydroxide, cobalt chloride, cobalt iodide, cobalt mineral salts such as cobalt nitrate, cobalt acetate, cobalt benzoate, and cobalt naphthenate. In addition to cobalt organic acid salts, cobalt carbonyl complexes such as dicobalt octacarbonyl, tetracobalt dodecacarbonyl, and cyclopentadienyl cobalt dicarbonyl, cobalt cene and cobalt acetylacetonate, various ligands are attached to cobalt. Examples include cobalt complexes. Among these cobalt compounds, cobalt oxides, cobalt halides, cobalt carbonyl complexes, and cobalt complexes having other ligands are preferred. Further, as the ruthenium compound and the cobalt compound, compounds containing ruthenium and cobalt can also be suitably used. An example of this is M[RuCo ₃
(CO) ₁₂ ], M [CoRu ₃ (CO) ₁₃ ] (where M is hydrogen or a cation).
Examples include cobalt heteronuclear complexes. The concentration of the ruthenium compound and cobalt compound used in the method of the present invention is expressed as the sum of the weights of ruthenium and cobalt in terms of metal.
0.01 relative to the total weight of liquid medium used in the reaction
-30% by weight, preferably 0.01-10% by weight.
The atomic ratio of ruthenium and cobalt compounds is 300:ruthenium:cobalt.
It is in the range of 1 to 1:100. The halogen-containing cocatalyst used in the method of the present invention includes ionic compounds containing halogen ions (hereinafter referred to as halogen salts), halogen-containing compounds capable of producing hydrogen halide under the reaction conditions (hereinafter referred to as halogen salts), Those known in the art can be used, such as hydrogen halide sources (referred to as hydrogen halide sources), and combinations of halogen salts and hydrogen halide sources. Examples of halogen salts include onium salts such as quaternary ammonium salts, quaternary phosphonium salts, and iminium salts, and metal salts such as alkali metal salts and alkaline earth metal salts. As the halogen ions constituting these salts, chloride ions, bromide ions, and iodine ions are preferred. Specific examples include ammonium salts such as tetramethylammonium chloride, tetrabutylammonium bromide, N-methylpyridium iodide, trimethylammonium chloride, triethylammonium bromide, and ammonium iodide, tetramethylphosphonium chloride, and tetrabutylphosphonium bromide. , n-heptyltriphenylphosphonium bromide, benzyltriphenylphosphonium iodide, quaternary phosphonium salts such as tetraphenylphosphonium chloride, bis(triphenylphosphine)iminium chloride, bis(triphenylphosphine)iminium iodide Iminium salts such as dide, lithium chloride, lithium bromide, lithium iodide, sodium chloride, potassium iodide, rubidium chloride, cesium iodide, magnesium chloride, calcium bromide,
Mention may be made of alkali and alkaline earth metal salts such as barium iodide, and the corresponding other halogen (Cl, Br and I) salts. Hydrogen halide sources include hydrogen halides (HCl, HBr,
Any material that can generate HI) may be used. Examples of this include halogens such as Cl ₂ , Br ₂ , I ₂ ,
Hydrogen halides such as HCl, HBr, HI, HClO,
Oxyacids such as HClO ₂ , HIO ₃ , organic halogen compounds such as methyl chloride, methyl bromide, methyl iodide, chloroform, dibromoethane, acetyl bromide, acetyl iodide, benzyl chloride, benzenesulfonyl chloride etc., CuBr ₂ , ZnI ₂ , _AlCl2 ,
ZrOCl ₂ , VOBr ₃ , CrCl ₃ , ReCl ₃ , RuCl ₃ , CoI ₂ ,
Examples include halides of metals from groups 1 to 10 of the periodic table, such as NiBr ₂ , and halides of nonmetallic elements, such as COCl ₂ , PBr ₃ , SOCl ₂ , and SiCl ₄ . Among these, halogen, hydrogen halide,
Methyl halides, acetyl halides, metal halides, and the like are preferably used. Further, these halogen-containing promoters can be used in combination with other promoters, if necessary. Such promoters include Lewis bases and Bronsted acids. Examples of the Lewis base include compounds containing Group 1 and Group 3 elements of the periodic table as donor atoms, such as amines, organic phosphines, ethers, esters, and thioethers. Examples of Brønsted acid and its precursors include phosphoric acid, phosphoric esters, phosphates, phosphorous acid, sulfuric acid, organic sulfonic acids, and carboxylic acids. The amount of cocatalyst used in the process of the invention is regulated relative to the amount of ruthenium compound used as catalyst. The amount of halogen salt used is from 0.01 to the number of gram atoms of ruthenium.
500 times the number of moles, preferably 0.1 to 250 times,
The amount of the hydrogen halide source used is 0.01 to 15 times, preferably 0.1 to 10 times the number of moles. The method of the invention is carried out in a liquid medium. As such a liquid medium, the above-mentioned organic phosphine oxide itself can be used, but the following solvents used in the present technical field can also be used in combination with the organic phosphine oxide. For example, heptane, octane, cyclohexane, decalin, tetralin, kerosene, benzene, toluene, xylene, diyulene,
Saturated and aromatic hydrocarbons such as hexamethylbenzene, halogenated hydrocarbons such as chloropentane, O-dichlorobenzene, p-chlorotoluene, fluorobenzene, dioxane, tetrahydrofuran, ethyl ether, anisole,
Ethers such as phenyl ether, diglyme, tetraglyme, 18-crown-6, esters such as methyl acetate, ethyl butyrate, methyl benzoate, r-butyrolactone, ketones such as acetone, acetophenone, benzophenone, N-methyl Pyrrolidin-2-one, N-ethylpyrrolidin-2-one, N・N-dimethylacetamide,
N-substituted amides such as N-methylpiperidone and hexamethylphosphoric triamide, N・N-
Tertiary amines such as diethylaniline, N-methylmorpholine, pyridine, and quinoline, sulfones such as sulfolane, sulfoxides such as dimethyl sulfoxide, urea derivatives such as 1,3-dimethyl-2-imidazolidinone, and , silicone oil, and special examples include molten salts such as quaternary ammonium salts, quaternary phosphonium salts, and iminium salts. Among these, preferably a low polar solvent (for example, a solvent with a dielectric constant ε of 30 or less, more preferably ε of 20 or less) is used. The reaction temperature in the method of the present invention is not particularly limited, but the lower limit is the temperature that provides a practical reaction rate, and the upper limit is the carbon monoxide necessary to solubilize the ruthenium compound and cobalt compound as catalysts. To prevent the partial pressure from becoming extremely high, to suppress the decomposition and reaction of the co-catalyst, to prevent the mechanical strength of the materials that make up the device from decreasing significantly, to prevent the corrosion of the materials from accelerating significantly, and to prevent methane, etc. It may be determined to suppress undesirable side reactions that produce . Usually, the reaction temperature range is 150-350°C, preferably 170-300°C. In addition, in the method of the present invention, the reaction pressure is set to the minimum carbon monoxide partial pressure necessary to solubilize the ruthenium compound and cobalt compound acting as the main catalyst at the reaction temperature, and to maintain a practical reaction rate. The lower limit is determined by the sum of the minimum hydrogen partial pressures required, and the upper limit is determined by economic limitations such as the pressure resistance of the reactor and the power required to compress carbon monoxide and hydrogen as raw materials for synthesis. limited. Usually the reaction pressure range is 30-1000 Kg/cm ² gauge, preferably 80-600 Kg/cm ² gauge. The molar ratio of carbon monoxide and hydrogen used as raw materials is preferably in the range of 1:10 to 10:1. Furthermore, gases such as carbon dioxide, methane, and nitrogen may be present in the synthesis gas. The method of the present invention can be carried out in batch mode, semi-continuous mode or continuous mode. The ruthenium compound, cobalt compound, cocatalyst, organic phosphine oxide, solvent, etc. can be fed to the reactor in a batch, semi-continuous or continuous manner. The product can be recovered by known methods such as distillation, stripping, etc. In some cases, the acetate produced can be decomposed into acetic acid and alcohol by hydrolysis, and each can be recovered. Also,
The liquid medium containing the catalyst, cocatalyst, organic phosphine oxide, solvent, etc. can be recycled back to the reactor for use. Hereinafter, the method of the present invention will be explained in more detail with reference to Examples. In the following examples, unless otherwise specified, the amounts of ruthenium used are expressed in milligram-atoms, and the amounts of cobalt, cocatalysts, promoters, and organic phosphine oxides are expressed in molar ratios (or atomic percentages) to the amount of ruthenium used. ratio)
The amount of solvent used is 15 ml. Further, the product yield is expressed as the number of millimoles of the product, and the production rate of the product is expressed as the turnover number (expressed as TON) [mol/Ru (g-atoms)/hr]. Furthermore, in Tables 1 to 3, the products are designated as methanol, ethanol and acetic acid, respectively, including those produced as their esters and ethers (dimethyl ether). In addition, unless otherwise specified, the ruthenium compound and cobalt compound used as catalysts are ruthenium carbonyl Ru ₃ (Co) ₁₂ and cobalt carbonyl Co ₂
(CO) ₈ , and each symbol represents the following compound. PPNCl and PPNI: bis(triphenylphosphine ₎ iminium chloride and iodide, HTBr: n-heptyltriphenylphosphonium bromide, _Et4NBr : tetraethylammonium bromide, _Me3PO4 : trimethyl phosphate, _Et3PO : triethylphosph in oxide,
Bu ₃ PO: tri-n-butylphosphine oxide, Hx ₃ PO: tri-n-hexylphosphine oxide, i-PrPh ₂ PO: i-propyl diphenylphosphine oxide, Ph ₃ PO: triphenylphosphine oxide , NMP: N-methylpyrrolidin-2-one, TL: toluene, B: benzene. Example 1 0.12 g of ruthenium carbonyl Ru ₃ (CO) ₁₂ (0.56 as Ru) was placed in a stainless steel autoclave with an internal volume of 50 ml (using a Pyrex glass liner).
milligram atom), cobalt carbonyl Co ₂
(CO) ₈ 0.144g (0.84 milligram atom as Co),
Bis(triphenylphosphine)iminium chloride (PPNCl) 2.01g, bis(triphenylphosphine)iminium iodide (PPNI)
0.558g, trimethyl phosphate 0.039g, tri-n-
Butylphosphine oxide, 2.94 g (14 mmol) and toluene 15 ml were charged, and synthesis gas (CO: _H2 molar ratio 1:1) was introduced to replace the air in the autoclave, and the synthesis gas was brought to room temperature. hand
Loaded up to 340Kg/cm ² gauge. Next, the autoclave is heated, and when the internal temperature reaches 80°C, stirring is started. When the internal temperature reaches 260°C, the temperature is maintained at a constant temperature, and synthesis gas is introduced through the pressure control valve to adjust the internal pressure of the autoclave. The reaction was carried out for 30 minutes while maintaining the gauge at 450Kg/ ^cm2 . After 30 minutes of reaction, the pressure control valve was closed, the autoclave was stopped from heating, and the autoclave was cooled to room temperature. Next, the contents were taken out and analyzed by gas chromatography. In the liquid phase, 2.20 mmol of methanol, ethanol
5.12 mmol, propanol 0.06 mmol, acetic acid
17.62 mmol of propionic acid, 0.72 mmol of propionic acid, 3.87 mmol of methyl acetate, 4.45 mmol of ethyl acetate, 1.00 mmol of propionate, 0.08 mmol of methyl formate, 0.09 mmol of dimethyl ether were detected, and carbon dioxide and 5.3 mmol of methane were detected in the gas phase. It was done. The reaction conditions and results are summarized in Table 1. Comparative Example a The same procedure as in Example 1 was carried out except that tri-n-butylphosphine oxide was not used. The reaction conditions and results are shown in Table 1. Comparative Example b In the autoclave used in Example 1, 0.06 g of ruthenium carbonyl (0.28 milligram atoms as Ru), 0.144 g of cobalt carbonyl, and 2.01 g of PPNCl were added.
g, PPNI 0.558 g, trimethyl phosphate 0.039 g, and toluene 15 ml were charged, and synthesis gas (CO:H ₂ =1:
1) was introduced to replace the air in the autoclave, and the autoclave was further pressurized to 340 Kg/cm ² gauge (room temperature). Next, heat the autoclave until the internal temperature reaches 260
When the temperature reached ℃, the temperature was kept constant and the reaction was carried out under stirring. When the internal pressure of the autoclave dropped to 350 Kg/cm ² gauge, heating was stopped and the autoclave was cooled to room temperature. The contents of the autoclave were then analyzed by gas chromatography. The reaction conditions and results are shown in Table 1. Example 2 The same procedure as Comparative Example b was carried out except that 0.938 g of triethylphosphine oxide was added. The reaction conditions and results are shown in Table 1. Additionally, 3 mmol of methane was detected in the gas phase. Example 3 The same procedure as Comparative Example b was carried out except that 10 g of triethylphosphine oxide was used instead of 15 ml of toluene. The reaction conditions and results are shown in Table 1. Additionally, 3.5 mmol of methane was detected in the gas phase. The results of the above examples and comparative examples show that the use of organic phosphine oxide improves the acetic acid synthesis activity (TON) and the acetic acid/ethanol production molar ratio. Example 4 Ruthenium acetylacetonate Ru (acac) ₃ and cobalt acetylacetonate Co (acac) ₃ as ruthenium and cobalt compounds
and 10 g of tri-n-hexylphosphine oxide instead of triethylphosphine oxide.
The same procedure as in Example 3 was carried out except that . The reaction conditions and results are shown in Table 1. Example 5 i-propyldiphenylphosphine oxide
The same procedure as Comparative Example b was carried out except that 3.42 g was added. The reaction conditions and results are shown in Table 1. Example 6 Except that the amount of triethylphosphine oxide used and the reaction temperature were changed as shown in Table 1,
It was carried out in the same manner as in Example 2. The reaction conditions and results are shown in Table 1. Additionally, 1.1 mmol of methane was detected in the gas phase. From this example, it can be seen that the lower the reaction temperature, the greater the molar ratio of acetic acid/ethanol produced. Example 7 and Comparative Example c The reaction conditions were changed as shown in Table 1, and the charging pressure of synthesis gas (CO:H ₂ = 1:1) was adjusted to 290 kg/
cm ² gauge (room temperature), the internal pressure of the autoclave when the heating of the autoclave is stopped and the reaction is terminated.
The same procedure as in Example 2 was carried out except that the gauge was 310 Kg/cm ² . The reaction conditions and results are shown in Table 1. Examples 8 to 11 and Comparative Example d Comparative Example b was carried out in the same manner as in Comparative Example b, except that the reaction conditions were changed as shown in Table 2. However, the synthesis gas charging pressure in Examples 8 and 10 was 320 and 360, respectively.
Kg/ ^cm2 . The results are shown in Table 2.

【table】

[Table] Example 12 The reaction was carried out in the same manner as in Example 1 except that the reaction conditions were changed as shown in Table 2. As a result of the analysis, the liquid phase contained 0.58 mmol of methanol, 1.69 mmol of ethanol, 0.17 mmol of propanol, and 11.33 mmol of acetic acid.
mmol, propionic acid 0.35 mmol, methyl acetate 2.10 mmol, ethyl acetate 1.35 mmol, propionate ester 0.28 mmol, methyl formate 0.07
0.10 mmol of dimethyl ether were detected, and carbon dioxide and 1.7 mmol of methane were detected in the gas phase. The results are summarized in Table 2. Example 13 and Comparative Example e Using [Ru(CO) ₃ Cl ₂ ] as the ruthenium compound, the charging pressure of synthesis gas (CO:H ₂ = 1:15) was 320 Kg/cm ² gauge (room temperature), and the autoclave was heated. Except that the internal pressure of the autoclave at the time of stopping the reaction and terminating the reaction was set to 300 Kg/ ^cm2 gauge, and other reaction conditions were changed as shown in Table 3.
It was carried out in the same manner as Comparative Example b. The results are shown in Table 3.

【table】

【table】

【table】

[Table] Example 14 The reaction conditions were changed as shown in Table 3, except that the synthesis gas charging pressure was 330 Kg/cm ² gauge.
It was carried out in the same manner as in Example 3. As a result of the analysis, the liquid phase contained 2.53 mmol of methanol, 2.80 mmol of ethanol, 0.50 mmol of propanol, and 15.17 mmol of acetic acid.
mmol, propionic acid 1.39 mmol, methyl acetate 1.07 mmol, ethyl acetate 1.72 mmol, propionate ester 0.73 mmol, ethyl formate 0.02
mmol was detected, and carbon dioxide and carbon dioxide were present in the gas phase.
3.8 mmol of methane was detected. The results are summarized in Table 3. Example 15 and Comparative Example f Using tetraethylammonium bromide as a cocatalyst, the reaction conditions were changed as shown in Table 3, and the synthesis gas charging pressure was 340 Kg/cm ² gauge (room temperature),
The same procedure as Comparative Example b was carried out except that the internal pressure of the autoclave at the end of the reaction was set to 330 Kg/cm ² gauge. The reaction conditions and results are shown in Table 3.

Claims (1)

[Claims] 1 When carbon monoxide and hydrogen are reacted under heat and pressure in a liquid medium containing a ruthenium compound, a cobalt compound, and a halogen-containing promoter, the general formula R ₃ P=0 (wherein R is 1 to 20 A method for selectively producing acetic acid and acetic acid ester, characterized in that the reaction is carried out in the presence of an organic phosphine oxide represented by an unsubstituted or substituted alkyl group or aryl group having 5 carbon atoms.