JPS6222973B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing ethylene glycol from synthesis gas, a mixed gas of carbon monoxide and hydrogen.

According to the method of the present invention, oxygen-containing compounds can be efficiently produced under relatively mild conditions.

Ethylene glycol is an important basic chemical with a wide range of applications, and there is always hope for an inexpensive industrial production method.

Conventionally, many methods using rhodium-based catalysts have been proposed as methods for directly producing ethylene glycol in one step using carbon monoxide and hydrogen as raw materials. However, these methods, such as those exemplified in Japanese Patent Publication No. 53-31122, use expensive rhodium, and are difficult to put into practical use on an industrial scale, such as recovering and reusing the rhodium catalyst. The fact is that the catalyst performance is not always sufficient, so it has not been completed as a practical process.

On the other hand, as one way to avoid the drawbacks of these rhodium catalysts, several methods have been proposed that use ruthenium catalysts, which are cheaper than rhodium. For example, U.S. Pat.
No. 4170605 discloses a method for producing ethylene glycol using a catalyst consisting of ruthenium and pyridine ligands. In this case, 2-hydroxypyridine is used as the pyridine ligand and ruthenium 1
Using 5.74 moles per g atom, 15000 psi (1057.8
Kg/cm ² ) is shown. In addition, other pyridine ligands include 2-aminopyridine,
An example of 2-(dimethylamino)pyridine is also described, but there is no example of it actually being used, and there is no description of what kind of effects can be obtained.

Furthermore, JP-A-56-100728 discloses a system in which a ruthenium compound is dispersed in a low-melting point phosphonium salt or ammonium salt, and JP-A-56-123925 discloses a catalyst system consisting of ruthenium and rhodium compounds. 〓〓
Publication No. 57-109735 discloses a catalyst system consisting of ruthenium and polyvalent phenols, JP-A-57-130939 discloses a catalyst system consisting of ruthenium and a rhenium compound, and JP-A 58-121226 discloses a catalyst system consisting of ruthenium and a manganese compound. A catalyst system has been proposed as a method for producing free ethylene glycol from carbon monoxide and hydrogen. However, the activity of the ruthenium-based catalysts disclosed in these publications cannot be said to be at a high level in any case.
Under relatively low pressure conditions of 600 Kg/cm ² or less, the production rate of ethylene glycol is about 1 mol ethylene glycol/gram atom/hour, and it is difficult to say that it still exhibits sufficient activity.

Furthermore, several methods have been proposed for synthesizing ethylene glycol ester from carbon monoxide and hydrogen using a system in which carboxylic acid is used as a reaction solvent and a ruthenium compound is dispersed as a catalyst. Japanese Unexamined Patent Publication 1973-
Publication No. 9088 proposes a method for simultaneously producing an alkanol ester and a vicinal glycol ester using a carboxylic acid as a solvent and a catalyst system containing ruthenium and osmium. In this specification, aliphatic carboxylic acids, aromatic carboxylic acids, and substituted products thereof are exemplified as carboxylic acids, but among these, acetic acid, trifluoroacetic acid, and propionic acid as shown in the examples are used. It is stated that such aliphatic carboxylic acids are preferred. Also, JP-A-56-
No. 51426 discloses a system using a ruthenium compound and a phosphonium salt in an aliphatic carboxylic acid solvent, and JP-A-56-123925 discloses a system using a mixture of ruthenium and rhodium compounds mainly in an acetic acid solvent. In US Pat. No. 4,323,513,
It has been proposed to maintain the concentrations of methyl ester, ethylene glycol ester, and water below 30% when producing ethylene glycol ester using a homogeneous liquid phase consisting of a ruthenium compound and a carboxylic acid.

However, even in systems using these carboxylic acids as reaction solvents, the production rate of ethylene glycol ester is low, and it is judged that the catalyst activity level for practical use has not been reached (under the reaction conditions of 600 kg/cm ² or less, the above-mentioned In any of the examples of the known technology, the production rate of ethylene glycol ester is about 1.0 mol/gram atom Ru·hr or less), and a hydrolysis step of ethylene glycol ester is required to produce ethylene glycol. It is difficult to say that it is necessarily advantageous as an industrial process.

The present inventors have arrived at the present invention as a result of extensive studies to increase the activity of ruthenium catalysts.

That is, the present invention provides a method for producing ethylene glycol by reacting carbon monoxide and hydrogen in the presence of a catalyst, in which the catalyst contains a ruthenium-containing compound and a total carbon number of 6 to 200 moles per gram atom of ruthenium. The present invention provides a method for producing ethylene glycol, characterized in that it contains the following monovalent or divalent aliphatic carboxylic acid or its halogen-substituted product, and an onium salt.

The ruthenium-containing compound used in the method of the present invention is not particularly limited, but examples thereof include ruthenium metal, ruthenium oxides, hydroxides, inorganic acid salts, organic acid salts, and complex compounds.

More specifically, for example, ruthenium dioxide,
Ruthenium tetroxide, ruthenium chloride, ruthenium bromide, tris(acetylacetone)ruthenium,
Dipotassium tetracarbonylruthenate, sodium hexachlororuthenate, pentacarbonylruthenium, dichlorotricarbonylruthenium, diiodotricarbonylruthenium, chlorotris(triphenylphosphine)hydridoruthenium, bis(tri-n-butylphosphine)tricarbonylruthenium , bis(tri-i)
-propylphosphine)tricarbonylruthenium, dodecacarbonyltriruthenium, tetrahydridododecacarbonyltetraruthenium, undecarbonylhydridotriruthenate tetraphenylphosphonium, tetracarbonylhydridoruthenate bis(triphenylphosphine)iminium, octadecacarbonylhexa Examples include dipotassium ruthenate.

The amount of ruthenium used is 1 x 10 ^-6 to 100 gram atoms, preferably 1 x 10 ^-5 to 10 gram atoms of ruthenium per liter of reaction solution, as a ruthenium concentration in the reaction solution.

In the method of the present invention, it is essential to use an aliphatic carboxylic acid as a reaction promoter together with the above-mentioned ruthenium-containing compound.

〓〓〓〓
The aliphatic carboxylic acids used as reaction accelerators include aliphatic monocarboxylic acids or dicarboxylic acids having a total carbon number of 6 or less and having a halogen substituent in the hydrocarbon chain.

Specific examples of such compounds include formic acid, acetic acid, propionic acid, butyric acid, chloroacetic acid, trifluoroacetic acid, maleic acid, succinic acid, malonic acid, and adipic acid.

The amount of these aliphatic carboxylic acids used is in the range of 0.1 to 200 mol per gram atom of ruthenium. If the amount of aliphatic carboxylic acid used is too small, its effect as a promoter is often small; if the amount used is too large, the promoting effect may not be maximized, or it may be mixed with the target product ethylene glycol. Since the carboxylic acid forms an ester, which causes problems such as complicating product separation and recycling systems, it is more preferable to use the ester in an amount of 0.5 to 100 mol per gram atom of ruthenium.

Additionally, onium salts are used as promoters as a third component for the catalyst components used in the process of the invention.

Examples of these onium salts include alkali metal salts, quaternary ammonium salts, quaternary phosphonium salts, and iminium salts.

More specific examples include tetramethylammonium chloride, tetraethylammonium iodide, tetra(n-butyl)ammonium chloride, tributyl ethylammonium iodide, trimethylbenzylammonium bromide, N-methylpyridinium chloride, ethyl-4-dimethylamino Pyridinium iodide, ethyl-1-methylimidazolium chloride, ethyl-1-methylbenzimidazolium iodide, bis(triphenylphosphine)iminium chloride, bis(triphenylphosphine)iminium bromide, bis(triphenyl) Examples include phosphine) iminium iodide, bis(triphenylphosphine) iminium benzoate, tetraethylphosphonium chloride, tetra(n-butyl)phosphonium iodide, triphenylmethylphosphonium chloride, and the like.

By adding the onium salt as the third component, a remarkable combined effect with the aliphatic carboxylic acid is observed.

These onium salts usually range from 0.05 to 500 moles per gram atom of ruthenium, preferably from 0.1 to 500 moles per gram atom of ruthenium.
Used in the range of 300 mol.

In the method of the present invention, a reaction solvent is used, and as the reaction solvent, those described below can be used. For example, ethers such as diethyl ether, tetrahydrofuran, dioxane, diethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether, ketones such as acetone, diethyl ketone, and acetophenone, alcohols such as methanol, ethanol, n-butanol, and ethylene glycol, formic acid, and acetic acid. , carboxylic acids such as propionic acid, phenols such as phenol and methoxyphenol, esters such as methyl acetate, ethyl acetate, ethylene glycol diacetate, and γ-butyrolactone, sulfones such as sulfolane and dimethyl sulfone, dimethyl sulfoxide, and diethyl sulfoxide. sulfoxides such as N・N-dimethylformamide, N・N-dimethylacetamide,
Amides such as N-methylpyrrolidinone, N-isopropylpyrrolidinone, N-methyl-2-pyridone, N・N・N′・N′-tetramethylurea, N・
Substituted ureas such as N'-dimethylimidazolidinone, phosphoric acid triamides such as hexamethylphosphoric acid triamide and tripiperidinophosphine oxide, aromatic hydrocarbons such as benzene, toluene, xylene, and tetralin, n-hexane , aliphatic or alicyclic hydrocarbons such as n-octane, cyclohexane, and decalin, nitro compounds such as nitromethane and nitrobenzene, triethylamine, tri-n-butylamine, pyridine, N-methyl-piperidine, N-methylmorpholine, α- These include tertiary amines such as picoline, 2,6-lutidine, and 1-methylimidazole, nitriles such as acetonitrile and benzonitrile, and carbonic acid esters such as dimethyl carbonate and ethylene carbonate.

In the method of the present invention, the reaction is carried out under heated and pressurized conditions. The reaction pressure is usually 1 to 2000
Kg/ ^cm2G , preferably 30-1000Kg/ ^cm2G , more preferably 50-600Kg/ ^cm2G . At this time〓〓〓〓
The ratio of carbon monoxide and hydrogen supplied to the reaction system as raw material gas for ethylene glycol production is
Usually as a molar ratio of carbon monoxide to hydrogen gas
It ranges from 0.05 to 20, preferably from 0.1 to 10. The reaction temperature is usually 50 to 350℃, preferably
It is in the range of 100-300℃. Further, the reaction time is usually 0.1 to 20 hours, preferably 0.3 to 10 hours. The process can be carried out batchwise, semi-continuously or continuously.

In order to clarify the purpose of the present invention, N.N'-dimethylimidazolidinone was used as the reaction solvent and acetic acid was used as an example of the aliphatic carboxylic acid of the present invention, and Example 5 described below in a mixed solvent system of these was used. The reaction results are shown in Figure 1. FIG. 1 illustrates the production rate of ethylene glycol, ethylene glycol monoacetate and ethylene glycol diacetate from carbon monoxide and hydrogen, and the molar ratio of acetic acid per gram atom of ruthenium as parameters. The acetate to ruthenium ratio on the horizontal axis is
The point 1300 corresponds to the condition of acetic acid as a sole solvent. All of the above-mentioned known methods use reaction systems that use aliphatic carboxylic acids (mainly acetic acid) as the sole solvent, but as is clear from Figure 1, no ethylene glycol is produced and only trace amounts of ethylene glycol esters are produced. It was hot. On the other hand, when the molar ratio of acetic acid to ruthenium is in the range of 1 to 200, the amount of products having an ethylene glycol skeleton is extremely large, and it is clear that ethylene glycol, which is not a free ester, is the main product. . When the molar ratio of acetic acid to ruthenium exceeds 200, there is a region in which the amount of diester produced from monoester increases slightly. In other words, this means that the amount of aliphatic carboxylic acid specified in the present invention can be used as a reaction accelerator both for producing free ethylene glycol and for producing a product having an ethylene glycol skeleton. clearly shows the superiority of doing so.

By using the method of the present invention described above, the production rate of free ethylene glycol instead of ester form is dramatically increased under lower pressure, and by appropriately controlling various conditions, the production rate per unit ruthenium can be increased dramatically. We have discovered that it is possible to increase the activity of

The present invention will be explained in detail with reference to Examples below.
The present invention is not limited to the following examples.

Example 1 Ruthenium dodecacarbonyl 0.1 mg-atom, bis(triphenylphosphine)iminium chloride 1.2 mmol, adipic acid 0.6 mmol and N.
Add 7.5 ml of N′-dimethylimidazolidinone to the inner volume
It was sealed in a 35ml Hastelloy autoclave.
After installing this autoclave in a heating furnace, a mixed gas with a carbon monoxide to hydrogen molar ratio of 1:1 was introduced from the gas introduction pipe to replace the gas in the system, and the charging pressure was 360 Kg/cm ² G at room temperature. A mixed gas was charged. The reaction temperature was set at 240°C, and the reaction was carried out for 30 minutes from the time the set temperature was reached. During that time, the reaction pressure rose to 480Kg/cm ² G, and at the end of the reaction it was 380Kg/cm 2 G.
It decreased to Kg/cm ² G. After the reaction was completed, the autoclave was quickly cooled and the contents were analyzed by gas chromatography. The production rates of ethylene glycol and methanol are 18.5 and 18.5, respectively.
It was 239.8 mol/gram atom ruthenium/hour. Other reaction products include methane, carbon dioxide, methyl formate, and ethanol, as well as the production of some adipic acid esters.

Example 2 When the reaction was carried out under the same conditions as in Example 1 except that 0.6 mmol of acetic acid was used instead of adipic acid, the production rates of ethylene glycol and methanol were 20.8 and 193.9 mol/gram atom ruthenium-hour, respectively. It was hot.

Example 3 When the reaction was carried out under the same conditions as in Example 1 except that 0.6 mmol of trifluoroacetic acid was used instead of adipic acid, the production rates of ethylene glycol and methanol were 14.0 and 136.7 mol/gram atom ruthenium-hour, respectively. It was hot.

Example 4 When the reaction was carried out under the same conditions as in Example 1 except that 0.6 mmol of malonic acid was used instead of adipic acid, the production rates of ethylene glycol and methanol were 15.9 and 170.7 mol/gram atom ruthenium-hour, respectively. It was hot.

Example 5 Ruthenium dodecacarbonyl 0.1 mg - atom, bis(triphenylphosphine) iminium chlora〓〓〓〓
A reaction was carried out under the same reaction conditions as in Example 1. In this example, the reaction was carried out by varying the amount of acetic acid added as a reaction accelerator, but the amount of reaction solvent used was such that the total amount of N・N'-dimethylimidazolidinone and acetic acid was 7.5 ml. I considered it to be. Among the reaction products obtained, the relationship between the rate of the product having an ethylene glycol skeleton and the acetic acid to ruthenium ratio (mol/gram atom) is shown in FIG. From Figure 1, it can be seen that the amount of products with an ethylene glycol backbone (ethylene glycol, ethylene glycol monoacetate and ethylene glycol diacetate) is in the range of acetic acid to ruthenium ratios of 10 to 200 moles/gram atom, and in this region, free It was found that the main production was ethylene glycol. Furthermore, in the range where the acetic acid/ruthenium ratio exceeds 200 mol/gram atom, the production of products having an ethylene skeleton decreases significantly, and the production of ester products becomes the main product. The right end of Figure 1 corresponds to an acetic acid single solvent system with an acetic acid to ruthenium molar ratio of approximately 1300 moles/gram atom.
No products having an ethylene glycol skeleton were observed in this system.

[Brief explanation of the drawing]

FIG. 1 shows the experimental results conducted in Example 5 as a relationship between the rate of production of a product having an ethylene glycol skeleton and the ratio of added acetic acid and ruthenium compound. 1...Ethylene glycol, 2...Ethylene glycol monoacetate, 3...Ethylene glycol diacetate. 〓〓〓〓

Claims (1)

[Claims] 1. A method for producing ethylene glycol by reacting carbon monoxide and hydrogen in the presence of a catalyst, in which the catalyst contains a ruthenium-containing compound and a total carbon number of 6 to 200 moles per gram atom of ruthenium.
A method for producing ethylene glycol, which comprises the following monovalent or divalent aliphatic carboxylic acid or its halogen-substituted product, and an onium salt.