JPS641452B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for efficiently producing alcohols such as ethylene glycol and ethanol from carbon monoxide and hydrogen by a liquid phase reaction.

Ethylene glycol is a raw material for polyester,
Ethanol is used as an antifreeze agent, etc. Ethanol is used as a solvent, fuel, antifreeze agent, and various chemical raw materials, and may also be used as a raw material for ethylene, all of which are industrially important basic chemicals.

[Conventional technology]

Traditionally, these two-carbon alcohols ( _C2 alcohols) have been produced primarily from petroleum, but in recent years, with the aim of diversifying chemical raw materials, they have been produced from carbon sources such as coal, natural gas, and heavy oil. This kind of gas is produced from easily obtained carbon monoxide and hydrogen.
The development of technology to produce _C2 alcohol has become an important issue.

A method for producing _C2 alcohols such as ethylene glycol and ethanol from carbon monoxide and hydrogen through a liquid phase reaction is a method using a cobalt catalyst (US Pat. No. 2,534,018, US Pat. No. 2,636,046, etc.). ), method using ruthenium catalyst (U.S. Pat. No. 4,170,605, JP-A-Sho
55-115834, JP 57-109735, etc.)
Also, methods using rhodium catalysts have been proposed.

Many proposals have already been made regarding methods using rhodium catalysts, including quaternary ammonium salts (Japanese Unexamined Patent Publication No. 51-32506), alkali metal salts (Japanese Unexamined Patent Publication No. 51-36403), and bis-catalysts. (Tertiary phosphine) iminium salt (JP-A-51-63110
There is a method of adding such as Also,
A method of adding organic nitrogen ligands was published in 1972.
This method has been proposed in JP-A No. 42809, Japanese Patent Laid-Open No. 52-42810, etc. In this case, it has also been proposed to use imidazoles as organic nitrogen ligands (Japanese Unexamined Patent Publication No. 170022/1983). Furthermore, JP-A-55-9065
The publication describes a method of coexisting phosphine oxide. Further, JP-A-60-136524 and JP-A-60-149537 describe methods using trialkylphosphines.

[Problem that the invention seeks to solve]

However, the above method has a problem in that the production activity of C ₂ alcohol per catalyst metal [turnover number: number of moles of product/(g-atom catalyst metal/reaction time)] is low.

In addition, in the direct synthesis of ethylene glycol, methanol, methyl formate, ethanol, etc. are produced as by-products in addition to ethylene glycol, but in the conventional method,
As shown in Japanese Unexamined Patent Publication No. 59-170022, etc., there is a problem that a large amount of methanol with low added value is produced. There is a practical need to improve the selectivity of _two alcohols. In addition, when using a rhodium catalyst, it is important to use a ligand with good stability, and in the case of the imidazoles mentioned above, since they have unsaturated bonds in their molecules, they are still unstable in terms of stability. It's not something I can be satisfied with.

[Means for solving problems]

As a result of extensive research to overcome the above problems, the present inventors discovered that by allowing pyrrolidines to exist in the reaction system when reacting carbon monoxide and hydrogen using a catalyst containing rhodium, The present inventors have discovered that specific high catalytic activity and selectivity that could not be expected from the results of conventional methods have been achieved.

That is, the present invention provides a method for producing ethylene glycol and ethanol, which is characterized by using a rhodium-containing catalyst and allowing pyrrolidines to be present in the reaction system when carbon monoxide and hydrogen are reacted.

According to the present invention, C ₂ alcohols such as ethylene glycol and ethanol can be produced with high selectivity from synthesis gas by liquid phase reaction, so the present invention has great significance.

The present invention will be explained in detail below.

The pyrrolidines used in the present invention are represented by formula (1).

Here, R is an alkyl group such as methyl, ethyl, butyl, octyl, dodecyl, 2-hydroxyethyl, or a hydroxyalkyl group in which a part of the alkyl group is substituted with an OH group. Also, R′ is H,
It is an alkyl group or a hydroxyalkyl group.

The molar ratio of carbon monoxide and hydrogen used in the present invention is usually CO: _H2 = 1:10 to 5:1, preferably in the range of 1:4 to 2:1. The pressure of this mixed gas (synthesis gas) is 250Kg/cm ² to 3000Kg/cm ²
Preferably it is in the range of 300Kg/cm ² to 2000Kg/cm ² .
The pyrrolidines of the present invention can be used as reaction solvents. It can also be used after being diluted with a suitable diluent. As the diluent, those commonly used in this type of reaction can be used, but preferred diluents include benzene, toluene, xylene,
Hydrocarbons such as decalin, hexane, heptane and N
- pyrrolidones such as methylpyrrolidone, N-ethylpyrrolidone, alkyl ureas such as NN'-dimethylimidazolidinone, or tetrahydrofuran, crown ether, dioxane,
Examples include ethers such as dibutyl ether, ethyl phenyl ether, and tetraglyme.
These diluents can be used alone or as a mixture.

Although any ratio of the pyrrolidines to the diluent can be used, the ratio of the pyrrolidines in the total solvent is usually 1 wt% or more, preferably 3 wt% or more.

In the present invention, any rhodium compound or rhodium metal can be used as a catalyst as long as it can produce soluble active species under the reaction conditions.
Examples of rhodium compounds include tetrarhodium dodecacarbonyl, tris(acetylacetone)
Examples include rhodium, acetylacetonatodicarbonyl rhodium, rhodium oxide, and the like.

The catalyst concentration in the reaction solvent is usually 0.01×10 ^-3 g-atom to 5 g per reaction solution in terms of metallic rhodium.
−atom range, preferably 0.1×10 ⁻³ g−
It ranges from atom to 1 g-atom. The reaction temperature is carried out in the range of 150 to 350°C, but the more preferable temperature range is 180 to 300°C.

The method of the present invention can be carried out in either batch or continuous reaction mode, and separation of the product and catalyst from the reaction solution can be easily carried out by known methods such as distillation and extraction. sell.

Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1 7 ml of N-methylpyrrolidine and tetrarhodium dodecacarbonyl were placed in a nitrogen-purged autoclave with an internal volume of 20 ml (made of Inconel steel).
After charging 0.00625 mmol and replacing the inside of the reactor with a mixed gas of CO:H ₂ = 1:1, a mixed gas of the same composition was pressurized and the reaction was carried out at 270°C for 1 hour under a constant pressure of 1800 kg/cm ² . . After the reaction, the autoclave was cooled and the products were analyzed by gas chromatography, which revealed that 22.05 mmol of ethylene glycol, 10.02 mmol of ethanol, 1.13 mmol of methanol,
0.18 mmol of methyl formate was obtained. The turnover numbers of ethylene glycol and ethanol are 882 mol/(g-atomRh)h and 400 mol/h, respectively.
(g-atomRh)h. In addition, the selectivity for C ₂ alcohol, which is a combination of ethylene glycol and ethanol, was 98%.

Here, the selectivity is expressed as carbon efficiency as shown in the following formula.

Ethylene glycol selectivity = 2 x EG x 100 / MeOH + MF + 2 x EtOH + 2EG Ethanol selectivity = 2 x EtOH x 100 / MeOH + MF + 2 x EtOH + 2EG MeOH: number of moles of ethanol produced, MF: number of moles of methyl formate produced, EtOH: number of moles of ethanol produced Number of moles produced, EG: Number of moles produced of ethylene glycol Comparative Example 1 When the reaction was carried out under the same conditions as in Example 1 except that 1-(3-methylbutyryl)pyrrolidine was used instead of N-methylpyrrolidine, ethylene glycol was 0.45%. Only 0.20 mmol of ethanol and 0.14 mmol of methanol were obtained.

Comparative Example 2 A reaction was carried out under the same conditions as in Example 1 except that pyrrolidine was used instead of N-methylpyrrolidine, but no production of ethylene glycol and ethanol was observed.

Example 2 A reaction was carried out under the same conditions as in Example 1 except that the reaction temperature was 230°C.
4.96 mmol of ethanol, 0.27 mmol of ethanol, 2.12 mmol of methanol and 0.09 mmol of methyl formate were obtained. The turnover numbers of ethylene glycol and ethanol are each 198 mol/(g-
atomRh)h and 10.8 mol/(g-atomRh)h. The selectivity for _C2 alcohol was 82.6%.

Comparative Example 3 A reaction was carried out under the same conditions as in Example 2 except that 7 ml of N-methylpyrrolidone was used instead of 7 ml of N-methylpyrrolidine.
0.69 mmol and 0.14 mmol of methanol were obtained. The turnover number of ethylene glycol is
It was 27.6 mol/(g-atomRh)h.

Example 3 2 ml of 1-(2-hydroxyethyl)pyrrolidine,
5ml of toluene and tetrarhodium dodecacarbonyl
The reaction was carried out under the same conditions as in Example 1 except that 0.025 mmol was used and the reaction temperature was 230°C.
Ethylene glycol 5.80 mmol, ethanol
0.43 mmol, methanol 11.46 mmol and methyl formate 1.51 mmol were obtained. The turnover number of ethylene glycol is 58.0mol/(g-
atomRh)h.

Comparative example 4 1-(2-hydroxyethyl)pyrrolidine 2 ml
The same conditions as in Example 3 were used except that 7 ml of toluene was used instead of 5 ml of toluene. Ethylene glycol 0.14 mmol, methanol 7.55
3.15 mmol of methyl formate were obtained.
No production of ethanol was observed. The turnover number of ethylene glycol is 1.4mol/(g
-atomRh)h.

Example 4 A reaction was carried out under the same conditions as in Example 1 except that the reaction temperature was 250°C. In this case, the amount of ethylene glycol produced was 12.25 mmol, and the amount of ethanol produced was 2.06 mmol. The turnover number of ethylene glycol is 490mol/(g-
atomRh)h. Additionally, 1.47 mmol of methanol and 0.24 mmol of methyl formate were obtained.

Example 5 A reaction was carried out under the same conditions as in Example 4, except that 7 ml of 1-methyl-2-pyrrolidine ethanol was used as the solvent. In this case, the amount of ethylene glycol produced was 8.69 mmol, and the amount of ethanol produced was 1.78 mmol. Additionally, 2.94 mmol of methanol and 0.14 mmol of methyl formate were obtained. The turnover number of ethylene glycol was 348.

Comparative Example 5 A reaction was carried out under the same conditions as in Example 1, except that 2 ml of N-methylpyrrolidine and 5 ml of tributylphosphine oxide were used instead of 7 ml of N-methylpyrrolidine, and 0.30 mmol of ethylene glycol, 0.04 mmol of ethanol, and 0.36 mmol of methanol were used. Obtained. The turnover number of ethylene glycol is
It was 12 mol/(g-atomRh)h.

Example 6 2 ml of 1-(2-hydroxyethyl)pyrrolidine
The reaction was carried out under the same conditions as in Comparative Example 5 except that 5 ml of N-ethylpyrrolidone and ethylene glycol were used.
6.00 mmol of ethanol, 3.8 mmol of ethanol, 1.71 mmol of methanol, and 0.11 mmol of methyl formate were obtained.

Example 7 7 ml of N-methylpyrrolidine and 0.025 mmol of tetrarhodium dodecacarbonyl were charged into an autoclave, and 1800 kg/cm ² was prepared in the same manner as in Example 1.
When the reaction was carried out at 230°C for 1 hour, 6.69 mmol of ethylene glycol, 0.46 mmol of ethanol, 6.06 mmol of methanol, and 0.35 mmol of methyl formate were obtained. The turnover number of ethylene glycol was 66.9 mol/(g-atomRh)h.

Example 8 The reaction was carried out in the same manner as in Example 7 except that 6 ml of N-methylpyrrolidine was coexisting with 1 ml of N-methylpyrrolidone. 9.27 mmol of ethylene glycol, 1.23 mmol of ethanol, 10.53 mmol of methanol,
0.57 mmol of methyl formate was obtained. The turnover number of ethylene glycol was 92.7. Compared to Example 7, the amount of C ₂ alcohol produced increased.

Example 9 1 ml of N,N'-dimethylimidazolidinone was coexisted with 6 ml of N-methylpyrrolidine, and the rest was Example 7.
Carry out the reaction in the same manner as ethylene glycol 9.69 mmol, ethanol 2.10 mmol, methanol
12.45 mmol and 0.69 mmol of methyl formate were obtained.
Compared to Example 7, the amount of C ₂ alcohol produced increased.

Example 10 A reaction was carried out under the same conditions as in Example 3 except that 2 ml of N-methylpyrrolidine and 5 ml of tetrahydrofuran were used, resulting in 9.90 mmol of ethylene glycol, 0.92 mmol of ethanol, and 15.07 mmol of methanol.
0.95 mmol of methyl formate was obtained.
The turnover number of ethylene glycol is
It was 99.0 mol/(g-atomRh)h.

Comparative Example 6 A reaction was carried out under the same conditions as in Example 10 except that 2 ml of N-methylpyrrolidine and 7 ml of tetrahydrofuran were used instead of 5 ml of tetrahydrofuran. 1.54 mmol of ethylene glycol, 10.33 mmol of methanol, and 2.36 mmol of methyl formate were obtained. Ta. The turnover number of ethylene glycol was 15.4 mol/(g-atomRh)h.

Example 11 An autoclave (manufactured by Hastelloy C) equipped with a magnetic induction stirring device with an internal volume of 40 ml was purged with nitrogen gas, and 0.1 mmol of rhodium acetylacetonate (biscarbonyl), 0.5 mmol of triisopropylphosphine, and 2 ml of N-methylpyrrolidine were added. , 3 ml of tetraglyme was charged, and the gas was replaced with a mixed gas of CO:H ₂ =1:1. Next, the autoclave was filled with a mixed gas of the same composition at 360 kg/cm ² at room temperature, and the reaction was carried out for 1 hour from the time when the temperature of the reaction system reached 230°C. The maximum pressure when the reaction temperature was reached was about 500 Kg/cm ² .

At the end of the reaction, cool the autoclave to room temperature,
Analysis of the reaction products by gas chromatography revealed 3.46 mmol of ethylene glycol, 0.16 mmol of ethanol, 4.62 mmol of methanol, 0.14 mmol of methyl formate, trace amounts of 1,2-propanediol, glycerin, and trace amounts of methane and CO as gas products. ₂ were detected.

The turnover number of ethylene glycol is
It was 34.5 mol/(g-atomRh)h.

Example 12 Under the conditions of Example 11, the pressure of the mixed gas was set to 490 at room temperature.
The reaction was carried out under the same conditions except that the amount was changed to Kg/cm ² . The maximum pressure when the reaction temperature was reached was approximately 685 Kg/cm ² .

Gas chromatographic analysis of the reaction products revealed that 5.1 mmol of ethylene glycol, 0.20 mmol of ethanol, 3.88 mmol of methanol, 0.15 mmol of methyl formate, and trace amounts of 1,2-propanediol, glycerin, methane, and CO ₂ were produced.

The turnover number of ethylene glycol is
It was 51.0 mol/(g-atomRh)h.

Example 13 A reaction was carried out for 2 hours under the conditions of Example 11, except that N-n-octylpyrrolidine was used instead of N-methylpyrrolidine.

Gas chromatographic analysis of the reaction products revealed 5.67 mmol of ethylene glycol, 0.13 mmol of ethanol, 4.31 mmol of methanol, 0.25 mmol of methyl formate, and trace amounts of 1,2-propanediol, glycerin, methane,
CO ₂ etc. were detected. In addition, the turnover number of ethylene glycol is 28.3 mol/(g-atomRh)
h was obtained.

Example 14 N-n-octylpyrrolidine under the conditions of Example 13
The reaction was carried out using 0.5 ml of tetraglyme and 4.5 ml of tetraglyme.

Gas chromatographic analysis of the reaction products revealed 4.75 mmol of ethylene glycol, 0.05 mmol of ethanol, 4.12 mmol of methanol, 0.34 mmol of methyl formate, and trace amounts of other products such as 1,2-propanediol, glycerin, methane, and _CO2 . was detected.

The turnover number of ethylene glycol is
It was 2.37 mol/(g-atomRh)h.

Example 15 In Example 13, 2 ml of N-n-dodecylpyrrolidine was used instead of N-n-octylpyrrolidine, and the reaction was carried out at a reaction temperature of 220°C for 2 hours.

Gas chromatographic analysis of the reaction products revealed that 3.12 mmol of ethylene glycol, 0.03 mmol of ethanol, 2.70 mmol of methanol, 0.33 mmol of methyl formate, and trace amounts of other components such as 1,2 propanediol, glycerin, methane, and CO ₂ were produced. .

The turnover number of ethylene glycol is
It was 23.7 mol/(g-atomRh)h.

Example 16 Using the same autoclave as Example 11,
Acetylacetonate (biscarbonyl) rhodium 1.0 mmol, triisopropylphosphine 2.0
mmol, N-methylpyrrolidine 0.5ml, N,
Add 5 ml of N'-dimethylimidazolidinone,
The reaction was carried out at 220°C for 15 minutes.

Gas chromatographic analysis of the reaction products revealed that 7.08 mmol of ethylene glycol, 0.09 mmol of ethanol, 3.48 mmol of methanol, 0.21 mmol of methyl formate, and trace amounts of 1,2-propanediol, glycerin, methane, and CO ₂ were produced. At this time, the turnover number of ethylene glycol was 28.3 mol/(g-atomRh)h.

Example 17 The inside of a 200 ml autoclave (manufactured by Hastelloy C) equipped with a magnetic induction stirring device was thoroughly replaced with nitrogen gas, and 1.4 mmol of rhodium acetylacetonate (biscarbonyl), 7.0 mmol of triisopropylphosphine, and N- After charging 15 ml of methylpyrrolidine and 45 ml of tetraglyme and replacing the inside of the autoclave with a mixed gas of CO:H ₂ = 1:1, a mixed gas of the same composition was introduced under pressure and the mixture was heated at 240°C under a constant pressure of 520 kg/cm ² . time to react.

After the reaction was completed, the autoclave was cooled, and the reaction products were taken out and analyzed by gas chromatography. As a result, ethylene glycol 54.50 mmol, ethanol 4.55 mmol, methanol 64.30 mmol, methanol 64.30 mmol,
Methyl formate 0.78 mmol, plus trace amounts of 1,2
Propanediol, glycerin, methane, CO2 _, etc. were obtained. At this time, the turnover number of ethylene glycol is 38.92 mol/(g-atomRh)
It was h.

Example 18 N-n-octylpyrrolidine under the conditions of Example 13
The reaction was carried out using 0.048 ml and 5.0 ml of tetraglyme.

Gas chromatographic analysis of the reaction products revealed 2.41 mmol of ethylene glycol, 0.01 mmol of ethanol, 6.21 mmol of methanol, 0.45 mmol of methyl formate, and trace amounts of other products such as 1,2-propanediol, glycerin, methane, and _CO2 . was detected.

The turnover number of ethylene glycol is
It was 12.1 mol/(g-atomRh)h.

Example 19 N-n-octylpyrrolidine under the conditions of Example 13
The reaction was carried out using 0.12 ml and 5.0 ml of tetraglyme.

Gas chromatography analysis of the reaction products revealed 3.13 mmol of ethylene glycol, 0.01 mmol of ethanol, 5.82 mmol of methanol, 0.39 mmol of methyl formate, and trace amounts of other products such as 1,2-propanediol, glycerin, methane, and _CO2 . was detected.

The turnover number of ethylene glycol is
It was 15.7 mol/(g-atomRh)h.

〔effect〕

According to the method of the present invention, it is possible to produce _C2 alcohols such as ethylene glycol and ethanol in high yields that were not possible with conventional catalyst systems.

Claims (1)

[Claims] 1. When carbon monoxide and hydrogen are reacted using a rhodium-containing catalyst, the following formula (1) is added to the reaction system:
(In the formula, R is an alkyl group or a part of the alkyl group is
The presence of a pyrrolidine represented by a hydroxyalkyl group substituted with an OH group, where R' is H, an alkyl group, or a hydroxyalkyl group (unless trialkylphosphine oxide is used in combination) A method for producing ethylene glycol and ethanol, characterized by: