JPS6055048B2 - Ethanol manufacturing method - Google Patents

Description

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

Conventionally, a method for producing ethanol from methanol, carbon monoxide, and hydrogen uses a cobalt compound as a catalyst, and if necessary, iodine or an iodide, ruthenium, or an osmium compound is also used in combination. .
In addition to ethanol, this method uses dimethyl ether,
Many by-products such as methyl ethyl ether, diethyl ether, acetaldehyde, dimethoxyethane, acetic acid, methyl acetate, ethyl acetate, methyl formate, and other compounds of Cs or higher are produced simultaneously, and the selectivity to free ethanol is low, and This method had drawbacks such as requiring a complicated process to separate ethanol from the reaction product. In recent years, catalyst systems have been proposed in which, in addition to the above catalyst systems, various ligands such as tertiary phosphine, tertiary arsine, and tertiary antimony are combined as promoters.

For example, British Patent No. 1,546,428 describes a method in which methanol, carbon monoxide, and hydrogen are reacted using a hydrocarbon as a solvent in the presence of a cobalt-iodide or bromide-tertiary phosphine catalyst.

UK patent 2036739 covers cobalt and other Group 8 metals (
Fe, Ru, Os, Rh, Ir, Ni, Pd and pt
) in the presence of iodine or bromine as a promoter and a tertiary phosphine.

However, the method of combining ligands such as the tertiary phosphine represented above tends to suppress the by-product of ethers and esters, but the addition of the ligand reduces the catalytic activity. As a result, in addition to the above-mentioned by-products, there are many high-boiling products that cannot be detected by gas chromatography, and the selectivity to free ethanol is not necessarily sufficient. It was difficult to say.

The inventors of the present invention have conducted intensive studies to resolve various drawbacks in conventional methods, and have found that methanol, carbon monoxide, and hydrogen are combined into 1, cobalt carbonyl, 2, tertiary phosphine,
By using cobalt sulfate as a cocatalyst when producing ethanol in the presence of a catalyst containing as an active ingredient, the by-product is essentially methyl formate, and ethanol can be produced with high selectivity. They discovered that it can be synthesized and completed the present invention.

That is, according to the present invention, dimethyl ether, methyl ethyl ether,
Since methyl acetate and the like are not substantially produced, the separation and purification process of ethanol can be extremely simplified, thereby providing an industrially advantageous method for producing ethanol.

In addition to cobalt carbonyls such as dicobalt octacarbonyl and cobalt hydride tetracarbonyl, the cobalt carbonyl catalysts used in the present invention include inorganic cobalt compounds such as cobalt hydroxide, cobalt carbonate, and basic cobalt carbonate, cobalt organic acid salts, cobaltocene, and cobalt. Various cobalt compounds that produce cobalt carbonyl within the reaction system may be used, including organic cobalt compounds such as acetylacetate.

The amount of cobalt carbonyl used is 1 to 300 m9 atoms in terms of cobalt atoms, preferably 5
~100 mg atoms.

Even if the amount is less than this, the reaction will proceed, but the reaction rate will be slow. If the amount exceeds this range, there will be no adverse effect, but it will not be economical. The amount of cobalt sulfate used in the present invention is 0.01 to 0.7 atoms of sulfur per 1 atom of total cobalt,
Preferably, the amount of cobalt is in the range of 0.05 to 0.5 atoms, but the total amount of cobalt relative to methanol must be within the above range.

Examples of the tertiary phosphine in the present invention include tri-n-butylphosphine, triphenylniphosphine,
Tri-valatrilylphosphine, tricyclohexylphosphine, 1,4-bisdiphenylphosphinobutane,
1,6-bisdiphenylphosphinohexane and the like can be used.

The amount of tertiary phosphine used is 1 mole of methanol! Hit,
2 to 600 m9 atoms as phosphorus atoms, preferably 10 to
200m9 atoms.

When the amount is less than this range, the effect of suppressing by-products of ethers and esters is small, and when it is more than this range, the methanol reaction rate and ethanol selectivity decrease, which is not preferable. Sulfur to methanol reaction rate (%) =…Excellence? The atomic ratio of the phosphorus charged in Menono 74V is 1:0.01 to 0.7:0.1 to 2, preferably 1
:0.05-0.5:0.5-1.8.

Outside this range, ethers, esters, and high-boiling products will increase, which is not preferable. Although the method of the present invention can be carried out without the use of a solvent, its effectiveness is further enhanced when carried out in the presence of an inert solvent that does not adversely affect the reaction.

Particularly preferred as the inert solvent are hydrocarbons, ethers, and esters.

Hydrocarbon solvents include aromatic hydrocarbons such as benzene, toluene, xylene, aliphatic hydrocarbons such as hexane, octane, and alicyclic hydrocarbons such as cyclohexane. As the ether solvent, diethyl ether, diisopropyl ether, dioxane, tetrahydrofuran, etc. can be used. As the ester solvent, methyl acetate, ethyl acetate, etc. can be used. The amount of solvent used is methanol 1
Per mole, it is 0 to 5 mol, preferably 0 to 2 mol.
If the amount is more than this, there will be no problem with the reaction, but the space-time yield will be small, making it impractical. The reaction temperature varies depending on the catalyst system used and other reaction conditions, but is generally 150'
C to 300'C1, preferably 200°C to 260°C.

Even if the amount is lower than this, the reaction will proceed, but the reaction rate will be slow.
If it exceeds this range, the amount of by-products will increase, which is not preferable.
The reaction pressure only needs to be 50 kg/d or more, and although there is no particular upper limit, a range of 150 to 450 k9/Crl is practically suitable.

The molar ratio of carbon monoxide to hydrogen ranges from 4:1 to 1:4, preferably from 2:1 to 1:3. Carbon monoxide and hydrogen used in the reaction include, for example, argon, nitrogen, carbon dioxide,
Inert gases such as methane and ethane 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. The method of the present invention can be carried out either batchwise or continuously.

Methanol reaction rate in the following examples and comparative examples,
The ethanol selectivity, the actual methanol conversion rate, and the realizable ethanol selectivity are defined as follows.

- Bed reaction methanol mol XlOO Tanol, mol Example 1 In a shaking autoclave manufactured by Hasteroe C with an internal volume of 100 m1, methanol 10y (0.3121 mol), dicobalt octacarbonyl 2y (0.0058 mol), cobalt sulfate 7 hydrate 0.56y (0.002 mol),
tri-n-butylphosphine 3f (0.0148 mol)
, 10y (0.1086 mol) of toluene was charged, and then a mixed gas of hydrogen and carbon monoxide (H2/CO molar ratio = 1) was added.
200k9/(4) was injected and reacted at 230°C for 3 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 methanol conversion rate was 25.
5%, and the free ethanol selectivity was 84.2%. In addition to methyl formate, which was produced with a selectivity of 8.6%, dimethyl ether, methyl ethyl ether, methyl acetate,
The production of ethyl acetate was in trace amounts. This is a realizable ethanol selectivity of 92.2% at an actual methanol conversion rate of 23.3%. Example 2 A reaction was carried out in the same manner as in Example 1 except that 0.28 fI (0.001 mol) of cobalt sulfate heptahydrate was used.

As a result, the methanol conversion rate was 26.5% and the free ethanol was 81.3%. Additionally, 6.7% methyl formate
Dimethyl ether, methyl ethyl ether, methyl acetate, and ethyl acetate were produced in trace amounts. This is a realizable ethanol selectivity of 87.1% at an actual methanol conversion rate of 24.7%.
Example 3 Cobalt sulfate heptahydrate 1.68V (0.00
The reaction was carried out in the same manner as in Example 1 except that 6 mol) was used.

As a result, the methanol conversion rate was 23.9% and the free ethanol selectivity was 78.9%. In addition, methyl formate is 9
．． Except for the production with a selectivity of 5%, trace amounts of dimethyl ether, methyl ethyl ether, methyl acetate, and ethyl acetate were produced. This is the actual methanol conversion rate of 21.6
%, the achievable ethanol selectivity is 87.2%. Comparative Example 1 Methanol 10f (0.3121 mol), dicobalt octacarbonyl 2g (0.0058 mol), trin-
The reaction was carried out in the same manner as in Example 1 except that butylphosphine 3y (0.0148 mol) and toluene 10y (0.1086 mol) were used.

As a result, the methanol conversion rate was 2% and 7%, the ethanol selectivity was 56.3%, and the selectivity to other components was 7.0% for methyl formate, 0.6% for methyl acetate, and 2.7% for methyl ethyl ether. Ta. This is an ethanol selectivity of 63% that can be achieved at an actual methanol conversion rate of 26.3%.
It is 3%. Comparative Example 2 A reaction was carried out in the same manner as in Comparative Example 1, except that 3.3 fI (0.0117 mol) of cobalt sulfate was used in place of dicobalt octacarbonyl.

Claims (1)

[Claims] 1. Using cobalt sulfate as a promoter when producing ethanol by reacting methanol, carbon monoxide, and hydrogen in the presence of a catalyst containing (1) cobalt carbonyl and (2) tertiary phosphine as active ingredients. A method for producing ethanol, characterized by: