JPS61204146A - Production of ethanol - Google Patents

Abstract

PURPOSE:To producing ethanol form methanol, carbon monoxide, and hydrogen, to obtain the aimed compound selectively, by adding a specific amount of tertiary phosphine oxide to a specific amount of a cobalt-ruthemium-iodine catalyst to suppress side reactions. CONSTITUTION:Methanol is reacted with carbon monoxide and hydrogen in the presence of a catalyst comprising (a) 0.1-100mg atom, especially 0.5-50mg atom based on 1mol methanol of Co, (b) 0.01-2 atom ratio, preferably 0.05-1 atom ratio based on Co of Ru, (c) 0.1-10 atom ratio, especially 0.5-4 atom ratio based on Co of I, and (d) 0.5-50 atom ratio, especially 1-20 atom ratio calculated at P atom based on Co of tertiary phosphine oxide as active ingredients preferably at 150-250 deg.C at 100-500kg/cm<2>G pressure, to give free ethanol in high space time yield in high selectivity under a relatively mild condition while suppressing extremely formation of by-products, especially ethyl methyl ether.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for selectively producing ethanol from methanol, carbon monoxide, and hydrogen.

(Prior art) Conventionally, as a method for producing ethanol from methanol, carbon oxide, and hydrogen, cobalt is used as a main catalyst, iodine or bromine is added as a promoter, and compounds such as ruthenium, osmium, iron, etc. Alternatively, methods are known in which various ligands and the like are used in combination.

For example, Japanese Patent Publication No. 38-24863 and Japanese Patent Publication No. 56-1
No. 56224 is a method in which methanol is reacted with carbon monoxide and hydrogen in the presence of a cobalt-iodine catalyst, either without a solvent or using a solvent.

U.S. Patent No. 3,285.948 and Japanese Unexamined Patent Publication No. 56-251
231; t, a method using a cobalt-ruthenium-iodine catalyst.

In recent years, catalyst systems have been proposed in which, in addition to the above catalyst systems, ligands such as tertiary phosphine, tertiary antimony, and tertiary arsine are combined as promoters. For example, UK patent 2,0
No. 36,739 is a method in which methanol is reacted with carbon monoxide and hydrogen in the presence of a cobalt-iodine or bromine-f$3 phosphine catalyst. Japanese Patent Publication No. 55-92330 is
cobalt, ruthenium, iodine and tertiary phosphine,
This is a method of reacting in the presence of a catalyst containing tertiary arsine or tertiary antimony as an active ingredient. Japanese Patent Publication No. 57-1080
No. 27 is a method in which a biproduct grade organic phosphine or phosphite is used as a ligand in a cobalt-ruthenium-iodine catalyst. JP-A-58-26830 discloses a method of reacting a cobalt-ruthenium-iodine catalyst using a polydentate ligand containing phosphorus or arsenic in one molecule as a ligand.

In addition, cobalt-based catalysts have also been proposed. For example, US Pat. No. 4,168,391 discloses a method in which methanol is reacted with carbon monoxide and hydrogen in the presence of cobalt carbonyl using a nonpolar, inert oxygen-containing compound as a solvent. U.S. Pat. No. 4,190,729 is the third patent from the viewpoint of stabilizing the catalyst and using it as a medium for catalyst recycling.
This method involves adding phosphine oxide.

(Problem to be Solved by the Invention) However, according to the results of the inventor's study on methods using the catalyst systems typified above, in addition to the target ethanol, dimethyl ether, ethyl methyl ether, acetaldehyde, dimethoxy Ethane, acetic acid, methyl acetate.

It was found that by-products such as ethyl acetate, methyl acetate, and other C3 or higher compounds were simultaneously produced, and the selectivity to free ethanol was insufficient.

In other words, a cobasite-iodine catalyst or a catalyst system in which it is combined with a ruthenium compound is easy to handle because it does not use a ligand, but it is difficult to produce ethers and methyl acetate among the above-mentioned by-products. Many have the disadvantage of low ethanol selectivity. In particular, ruthenium-added catalyst systems exhibit high hydrogenation activity at low temperatures, but a large amount of ethyl methyl ether is generated as a by-product at the same time as ethanol, and the suppression of ethyl methyl ether is a major issue in order to increase the selectivity to free ethanol. It is.

On the other hand, a catalyst system in which various ligands are combined with the above catalyst system tends to suppress the by-product of ethers, but the addition of the ligand reduces the catalytic activity, so the reaction temperature has to be raised. As a result, gaseous by-products such as methane from methanol, the liquid by-products mentioned above, and high-boiling products that cannot be detected by conventional gas chromatographic analysis are still produced (and the selectivity to free ethanol is low). It is difficult to say that it is necessarily high.

In addition, a cobalt-based catalyst system is preferable because it does not contain highly corrosive halogens or halides and the catalyst is a simple system. A low downside.

In these known methods, the activity and selectivity of the catalyst, especially the selectivity to free ethanol, are insufficient, and as a result, the separation and recovery of ethanol from the reaction product solution requires a complicated process. This is by no means a satisfactory method.

(Means for solving the problems) In order to solve the above-mentioned drawbacks of the conventional method, the present inventors
As a result of extensive research, we have found that by adding an appropriate amount of tertiary phosphine oxide to a Kobal)-ruthenium-iodine catalyst, by-products, especially ethyl methyl ether, can be greatly suppressed, and free ethanol can be reduced to a high level. The present invention was completed based on the discovery that it can be synthesized with high selectivity.

That is, in the present invention, when producing ethanol by reacting methanol, carbon monoxide, and hydrogen in the presence of a catalyst containing cobalt, ruthenium, iodine, and tertiary phosphine oxide as active ingredients, cobalt is added in an amount of 0.11% per mole of methanol. ~100~ atoms, ruthenium to cobalt in a range of 0.01 to 2 atomic ratios, iodine to cobalt in a range of 0.1 to 10 atomic ratios, tertiary phosphine oxide to cobalt in terms of phosphorus atoms 0.5-5 against
This is a method for producing ethanol by reacting in a range of 0 atomic ratios.

Examples of the cobalt catalyst in the present invention include cobalt carbonyl such as dicobalt octacarbonyl and cobalt hydride tetracarbonyl, as well as cobalt hydroxide, cobalt carbonate, basic cobalt carbonate, cobalt iodide, and cobalt bromide.

Various cobalt compounds that produce cobalt carbonyl in the reaction system can be used, including inorganic cobalt compounds such as cobalt chloride, organic cobalt salts, cobaltocene, and organic cobalt compounds such as cobalt acetylacetonate. The amount of the cobalt compound used is in the range of 0.1 to 10011 kg atoms, preferably in the range of 0.5 to 50 iy atoms, in terms of cobalt atoms per mole of methanol. When the amount is less than this, the reaction rate becomes low, and when it is more than this, there is no adverse effect, but it is not economical, and the above range is practical.

As a ruthenium source, ruthenium compounds.

For example, ruthenium chloride, ruthenium iodide, ruthenium oxide, ruthenium organic acid salts, ruthenocene, ruthenium acetylacetonate, ruthenium carbonyl, etc. Supported ruthenium catalysts, such as carbon, silica, alumina, silica/alumina, zilphnia, titania, etc. etc. can also be used. The amount of ruthenium used is in the range of 0.01 to 2 atomic ratio, preferably 0.05 to cobalt.
~1 atomic ratio. When the amount is less than this, the amount of by-products such as acetaldehyde and dimethoxyethane increases, and when it is more than this, the reaction rate becomes low.

Iodine sources include iodine and iodides, and those containing iodine can be used. for example.

Examples of iodides include hydrogen iodide, methyl iodide, sodium iodide, potassium iodide, and lithium iodide. The amount of iodine used is in the range of 0.1 to 10 atomic ratio, preferably 0.5 to 4 atomic ratio relative to cobalt. When the amount is less than this, the reaction rate is low, and when it is more than this, by-products such as dimethyl ether and acetaldehyde increase, and the selectivity to ethanol decreases.

Examples of the tertiary phosphine oxide used in the present invention include triethylphosphine oxide.

Tri-n-propylphosphine oxide, tri-n-butylphosphine oxide, tri-n-hexylphosphine oxide, triphenylphosphine oxide, tricyclohexylphosphine oxide, and the like can be used. The amount of tertiary phosphine oxide to be used is in the range of 0.5 to 50 atomic ratio in terms of phosphorus atom relative to cobalt, preferably 1
~20 atomic ratio. If it is less than this,
The by-product of ethyl methyl ether tends to increase, and when the amount is large, the by-product of methyl acetate tends to increase, and a high ethanol selectivity can be obtained within the above range.

An essential component of the catalyst in the present invention is cobalt.

It consists of ruthenium, iodine and tertiary phosphine oxide, but if necessary, elements 5 belonging to Group 8 of the periodic table, such as iron and nickel, can also be combined.

Although the catalyst system of the present invention can be carried out with or without the use of a solvent, its effectiveness is further enhanced when carried out in the presence of an inert solvent. Particularly preferred solvents include hydrocarbons and cyclic ethers.

Hydrocarbon solvents include aromatic hydrocarbons such as benzene, toluene, xylene, aliphatic hydrocarbons such as hexane, octane, and alicyclic hydrocarbons such as cyclohexane. As the cyclic ether, 1,4-dioxane,
Tetrahydrofuran etc. can be used. The amount of solvent used is
The weight ratio is in the range of 0 to 10, preferably 0 to 5, relative to methanol, and if it is more than this, the space-time yield becomes small and is not practical.

The reaction temperature in the present invention is in the range of 120 to 500°C, preferably 150 to 250°C.

If the temperature is lower than this, the reaction rate will be low, and if the temperature is higher than this, the amount of by-products will increase, which is not preferable.

The reaction pressure is 50%G or higher, and although there is no particular upper limit, a range of 100 to 500%G is suitable for practical use.

- The carbon oxide:hydrogen molar ratio is in the range 4:1 to 1:4, preferably in the range 2:1 to 1:3. In these gas mixtures.

An inert gas such as argon, nitrogen, carbon dioxide, methane, etc. may be mixed into the reaction, but in this case, the partial pressures of carbon monoxide and hydrogen must correspond to the above pressure range.

In the method of carrying out the present invention, compounds containing cobalt, ruthenium, iodine, and tertiary phosphine oxide, which are active components of the catalyst, and a solvent are usually charged all at once into a reactor, and methanol is reacted with carbon monoxide and hydrogen. Alternatively, each compound of the catalyst raw material can be heat-treated in a solvent under pressure with a mixed gas of carbon monoxide and hydrogen, and then this activated catalyst can be used to react methanol with carbon monoxide and hydrogen. .

(Effects of the Invention) According to the present invention, there is an advantage that free ethanol can be obtained with a high space-time yield and high selectivity under relatively mild conditions, and ethanol can be produced industrially advantageously. I can do it.

Note that the method of the present invention can be suitably carried out either by a batch method or a continuous method.

(Example) Next, the method of the present invention will be explained in more detail with reference to Examples.

The methanol conversion rate, ethanol selectivity, real methanol conversion rate, and convertible ethanol selectivity in Examples and Comparative Examples were defined as follows.

0 methanol reaction rate (%) O selectivity to each product (%) 0 actual methanol reaction rate (%) O convertible ethanol selectivity (%) Note 1) Hydrolysis of dimethoxyethane, methyl ester, etc. means the methanol fraction recovered by

Note 2) Free ethanol and acetaldehyde.

It refers to the ethanol content recovered by hydrogenation or hydrolysis of dimethoxyethane, ethyl methyl ether, etc.

Example 1 10 g (0,312 mol) of methanol, 10 g (0,128 mol) of benzene - Cobalt iodide IJ were placed in a shaking autoclave made of Hastelloy with an internal volume of 100 m7.
(3.2 mmol), ruthenium acetylacetonate o, 3y (o.

75 mmol) and tri-n-butylphosphine oxide 5,24.9 (24 mmol) were charged and the mixture was sealed.

A mixed gas of carbon oxide and hydrogen (H2/C0 = 2 molar ratio) was injected into this at 240 g, and at 175°C, 1.5
Allowed time to react.

After the reaction, the autoclave was cooled and residual gas was purged, and the reaction product liquid was analyzed using an internal standard method using gas chromatography.

As a result, the ethanol selectivity was 86.2% at a methanol conversion rate of 22.8%, and the selectivity for each other component was 0.70% for dimethyl ether and 0.5% for methyl formate.
4%, ethyl methyl ether 5.91%, methyl acetate 6.97%, n-propatol 0.77%, dimethoxyethane 0.81%, and ethyl acetate 0.92%. The actual methanol reaction rate at this time was 21.0%.
The selectivity of convertible ethanol was 94.5%.

Examples 2, 3 and 4 The amount of tri-n-butylphosphine oxide added was 1.7
5.9 (8 mmol), 3.49.9 (16 mmol)
, and 6,99.9 (32 mmol), and methanol was reacted with carbon monoxide and hydrogen in the same manner as in Example 1. The results of each experiment are shown in Table 1. from now)
'When the amount of J-n-butylphosphine oxide added was increased, the main by-product, ethyl methyl ether, decreased.

It can be seen that the free ethanol selectivity is correspondingly significantly improved.

, Example 5 Ru/Co (atomic ratio) was changed, and as in Example 1,
Methanol was reacted with carbon monoxide and hydrogen. The experimental results are shown in Table 1.

Examples 6 and 7 Methanol, carbon monoxide, and hydrogen were reacted in the same manner as in Example 1, using tri-n-propylphosphine oxide and tri-n-hexylphosphine oxide as the tertiary phosphine oxide. The results are shown in Table 2.

Examples 8 and 9 Same as Example 1 using ruthenium oxide and 5% ruthenium-carbon as ruthenium catalyst, benzene and n-octane as solvents.

Methanol was reacted with carbon monoxide and hydrogen.

The results of each experiment are shown in Table 2.

Example 10 Ferrous iodide was added as a promoter, and methanol, carbon monoxide, and hydrogen were reacted in the same manner as in Example 1. The experimental results are shown in Table 2.

Example 11 Examples 1 to 10 are a normal in+5 itu method in which methanol, a solvent, each compound as a catalyst source, -carbon oxide, and hydrogen are charged into a reactor all at once and reacted.

Next, a method is described in which each compound of the catalyst source is heat-treated in the presence of a solvent under pressure of a mixed gas of carbon monoxide and hydrogen, and then methanol is reacted with carbon monoxide and hydrogen in the presence of this catalyst liquid. .

10 g of benzene and basic cobalt carbonate (2Co
CO3・3Co(OH)2)O,,35,9(0,60
mmol), ruthenium chloride (RuCA!3/3
H20) 0, 1 1, li+ (
0.42 mmol), iodine 0.82.1 il (5
, 2 mmol).

and tri-n-butylphosphine oxide 5.241
! (24.0 mmol) was charged and the mixture was sealed. - Mixed gas of carbon oxide and hydrogen (H2/C0 = 2 molar ratio)
240 kg was press-fitted and heat-treated at 175° C. for 1 hour.

Next, after cooling the autoclave and purging residual gas, 10.9 (0,312 mol) of methanol was charged and the autoclave was sealed. Again, - mixed gas of carbon oxide and hydrogen (H2
/C0=2 molar ratio) 240kJgIG was press-fitted and 17
The reaction was carried out at 5°C for 1.5 hours.

After the reaction, the autoclave was cooled and residual gas was purged, and the reaction product liquid was analyzed using an internal standard method using gas chromatography.

As a result, the ethanol selectivity was 77.9% at a methanol conversion rate of 26.0%, and the selectivity for each other component was 0.62% for dimethyl ether and 0.62% for acetaldehyde.
0.16%, methyl formate 0.12%, ethyl methyl ether 5.08%, methyl acetate 6.62%, n-propatol 1.06%, dimethoxyethane 1.30
%, ethyl acetate 0.97%. The actual methanol conversion rate at this time was 24.0%, and the selectivity of convertible ethanol was 88.2%.

Comparative Example 1 Methanol 10. r (0,312 mol), benzene
10.9 (0,128 mol), cobalt iodide 1.9
(3.2 mmol) and 0.30 II (0.75 mmol) of ruthenium acetylacetonate were charged, and otherwise methanol, carbon monoxide, and hydrogen were reacted in the same manner as in Example 1. As a result, the ethanol selectivity was 51.2% at a methanol conversion rate of 41.4%.

Selectivity to other components is dimethyl ether 2.54%
, acetaldehyde 0.34%.

Methyl formate 0.06%, ethyl methyl ether 19
．． 7%, methyl acetate 2.50%, n-propertool
1.16%, dimethoxyethane 1.63%, and ethyl acetate 0.56%. The actual methanol conversion rate at this time was 55.3%, and the selectivity of convertible ethanol was 75.5%.

Comparative Example 1 corresponds to Examples 1.2, 5.4.6 and 7. A comparison of the experimental results shows that without the addition of tertiary phosphine oxide, ethyl methyl ether is produced as a significant by-product, and the selectivity of free ethanol is low.

Comparative Example 2 Methanol 10.9 (0,!112 mol), benzene 10II (0,128 mol), cobalt iodide 1!
! (3.2 mmol) and tri-n-butylphosphine oxide 5.24I (24.0 main 13 mol) were charged, and methanol, carbon monoxide, and hydrogen were reacted in the same manner as in Example 1. The experimental results are shown in Table 3.

Comparative Example 3 Methanol 10II (0,312 mol), benzene
10Ii (0,128 mol), dicobalt octacarbonyl 0.5579 (1,6 mmol) and trin
-Butylphosphine oxide 5.24 J (24.0 mmol) was charged, and methanol, carbon monoxide, and hydrogen were reacted in the same manner as in Example 1 except for the following. The experimental results are shown in Table 3.

Comparative Examples 2 and 3 correspond to Example 1. Comparative examples 1 and 2
Comparison of Example 3 and Example 1 shows that cobalt, ruthenium diiodine, and tertiary phosphine oxide are essential as active components of the catalyst in order to obtain a high free ethanol selectivity.

Comparative Examples 4 to 9 Tri-n-butylphosphine was used instead of tri-n-butylphosphine oxyto.

Ru/Co (ffl ratio) and (n-C4H9)
3 P/C.

(mol/9 atoms) was changed, and methanol, carbon monoxide, and hydrogen were reacted in the same manner as in Example 1 except for the following. The results of each experiment are shown in Tables 3 and 5, and these results correspond to Examples 1, 2, 3.4 and 5. From the notation comparison, T! A high free ethanol selectivity was not obtained with the addition of j-n-butylphosphine.

Claims (1)

[Claims] When producing ethanol by reacting methanol, carbon monoxide, and hydrogen in the presence of a catalyst containing cobalt, ruthenium, iodine, and tertiary phosphine oxide as active ingredients, cobalt is added in an amount of 0.1 to 100 m per mol of methanol.
g atom range, 0.01 to ruthenium to cobalt
2 atomic ratio range, 0.1 to 10 iodine to cobalt
A method for producing ethanol, characterized by reacting tertiary phosphine oxide in an atomic ratio of 0.5 to 50 with respect to cobalt in terms of phosphorus atoms.