JPS621932B2 - - 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, as a method for producing ethanol from methanol, carbon monoxide and hydrogen, a method has been known in which a cobalt compound is used as a catalyst, and if necessary, iodine or an iodide, ruthenium, osmium, a rhenium compound, etc. are also used in combination. It is being For example, US Pat. No. 3,285,948 is a method of reacting methanol, carbon monoxide and hydrogen in the presence of a soluble cobalt compound, iodine or iodide, and a ruthenium compound. However, in addition to ethanol, these methods simultaneously generate numerous byproducts such as dimethyl ether, methyl ethyl ether, diethyl ether, acetaldehyde, dimethoxyethane, acetic acid, methyl acetate, ethyl acetate, methyl formate, and other compounds with C3 _or higher. , the selectivity of free ethanol was low, and the separation of ethanol from the reaction product solution required a complicated process. In recent years, in addition to the above catalyst system, a tertiary catalyst has been used as a promoter.
Catalyst systems combining ligands such as phosphine, tertiary arsine, and tertiary antimony have been proposed. For example, JP-A-54-73708 discloses that tertiary phosphine or tertiary amine is used alone as a ligand in a cobalt-iodine or bromine-based catalyst, and methanol and This is a method of reacting carbon monoxide and hydrogen. or,
JP-A-55-92330 discloses a method in which the reaction is carried out in the presence of a catalyst containing cobalt, ruthenium, iodine, and tertiary phosphine, tertiary arsine, or tertiary antimony as active ingredients. However, according to the studies of the present inventors, in the method of combining the above-mentioned ligands with cobalt-iodine or bromine-based catalysts and cobalt-ruthenium-iodine or bromine-based catalysts, methane from methanol, etc. Many gaseous by-products, the various liquid by-products mentioned above, and even high-boiling products that cannot be detected by gas chromatography analysis are still produced.
Selectivity to free ethanol is not always sufficient. As a result of extensive research in order to eliminate various drawbacks of conventional methods, the present inventors have discovered that a third
The present invention has been completed by discovering that by combining appropriate amounts of phosphine and tertiary amine different ligands, various by-products can be significantly reduced and ethanol can be produced with high selectivity. That is, the present invention, when producing ethanol by reacting methanol, carbon monoxide, and hydrogen,
As a catalyst, per mole of methanol, (1) a cobalt compound with an amount of 0.1 to 100 mg in terms of a cobalt atom, (2) a ruthenium compound with an amount of 0.05 to 50 mg in terms of a ruthenium atom, (3) a tertiary phosphine with an amount of 0.2 to 200 mg in terms of a phosphorus atom, and (4) Using 0.1 to 100 mg of tertiary amine in terms of nitrogen atoms, and setting the atomic ratio of cobalt:ruthenium:phosphorus:nitrogen to 1:0.05 to 1:0.2 to 10:0.1.
This is a method in which the reaction temperature is maintained at ~5 and the reaction is performed in the absence of iodine. Cobalt compounds in the present invention include, in addition to cobalt carbonyl such as dicobalt octacarbonyl and cobalt hydride tetracarbonyl,
Various cobalt compounds that produce cobalt carbonyl in the reaction system include inorganic cobalt compounds such as cobalt hydroxide, cobalt carbonate, and basic cobalt carbonate, organic cobalt salts, cobaltcene, and organic cobalt compounds such as cobalt acetylacetonate. Can be used. The amount of cobalt compound used is 0.1 to 100 in terms of cobalt atoms per mole of methanol.
mg atoms, preferably 0.5 to 50 mg atoms. From this point on, the reaction at least proceeds, but the reaction rate becomes slower. As the ruthenium compound in the present invention, for example, organic acid salts such as ruthenium chloride, ruthenium oxide, and ruthenium acetate, ruthenocene, ruthenium acetylacetonate, and ruthenium carbonyl can be used. The amount of ruthenium compound used is 0.05 to 0.05 ruthenium atoms per mole of methanol.
50 mg atoms, preferably 0.1-25 mg atoms. Examples of the tertiary phosphine in the present invention include tri-n-butylphosphine, triphenylphosphine, tricyclohexylphosphine, 1,
6-bisdiphenylphosphinohexane and the like can be used. The amount of the tertiary phosphine used is 0.2 to 200 mg atoms, preferably 1 to 100 mg atoms, in terms of phosphorus atoms per mole of methanol. Examples of the tertiary amine in the present invention include trimethylamine, triethylamine, pyridine,
These include 2,6-lutidine, piperidine, and N-methylpiperidine. The amount of tertiary amine used is 0.1 to 100 mg atoms per mole of methanol, preferably
0.5-50 mg atoms. To suitably carry out the present invention, the atomic ratio of cobalt:ruthenium:phosphorus:nitrogen is 1:0.05 to 1:0.2.
~10:0.1~5, preferably 1:0.1~0.5:0.5~
5: Maintain within the range of 0.2 to 2. Although the present invention can be carried out without using a solvent,
The effect is further enhanced when carried out in the presence of an inert solvent. As the inert solvent, hydrocarbons, cyclic ethers, etc. are particularly preferred. As the hydrocarbon solvent, aromatic hydrocarbons such as benzene, toluene, and xylene, aliphatic hydrocarbons such as hexane and octane, and alicyclic hydrocarbons such as cyclohexane can be used.As the cyclic ether solvent, 1,4- Dioxane, tetrahydrofuran, etc. can be used. The amount of solvent used is 0 to 5 mol, preferably 0 to 2 mol, per mol of methanol. If the amount is more than this, the space-time yield becomes small and it is not practical. The reaction temperature in the present invention is 120-300°C, preferably 150-250°C. If the temperature is lower than this, the reaction rate will be low, and if it exceeds this range, by-products will increase, which is not preferable. The reaction pressure is 50 Kg/cm ² G or more, and although there is no particular upper limit, a range of 100 to 500 Kg/cm ² G is practically preferred. The molar ratio of carbon monoxide:hydrogen is 4:1
-1:4, preferably 2:1-1:3. These mixed gases may contain gases that are inert to the reaction, such as argon, nitrogen, carbon dioxide, methane, etc., but in this case, the partial pressures of carbon monoxide and hydrogen should be kept within the above pressure range. It is necessary to correspond to The method of the present invention can be carried out either batchwise or continuously. The methanol conversion rate, ethanol selectivity, actual methanol conversion rate, and achievable ethanol selectivity in the following Examples and Comparative Examples are defined as follows.

[Table] Example 1 In a stainless steel shaking autoclave with an internal volume of 100 ml, methanol 10 g (0.3121 mol), dicobalt octacarbonyl 2 g (5.8 mmol), and ruthenium acetylacetate Ru (AA) ₃ 0.52 g (1.3
mmol), tri-n-butylphosphine 3g
(14.8 mmol), N-methylpiperidine 0.67 g
(6.8 mmol) and benzene 10g (0.128 mol)
was prepared and sealed. The catalyst composition at this time is cobalt: ruthenium: phosphorus: nitrogen = 1:0.11:
1.28:0.59 (atomic ratio). Next, a mixed gas of hydrogen and carbon monoxide (H ₂ /CO = 1 molar ratio) was injected under pressure, and the mixture was 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. As a result, the methanol conversion rate was 23.8%.
The ethanol selectivity was 82.8%, and the selectivities for other components were: dimethyl ether 0.16%, acetaldehyde 0.25%, methyl formate 3.67%, methyl ethyl ether 1.0%, methyl acetate 1.01%, n
-Propanol 1.56%, dimethoxyethane 1.62%
It was hot. The actual methanol reaction rate at this time is
22.4%, and the achievable ethanol selectivity is
It became 89.4%. Examples 2 to 6 The following factors were varied in the same manner as in Example 1, and the experimental results are listed in Table 1. Examples 2 to 3; Reactions were carried out using N-methylpiperidine or triethylamine as the tertiary amine and tri-n-butylphosphine as the tertiary phosphine, and varying the combination ratio of the ligands within a specified range. Ivy. Example 4: A reaction was carried out using tri-n-hexylphosphine instead of tri-n-butylphosphine in Example 1. Example 5; instead of Ru(AA) ₃ in Example 1
The reaction was carried out using RuCL _{3.3H 2} O. Example 6; Basic cobalt carbonate 2CoCO ₃ 3Co(OH) ₂ as the cobalt source, RuCL ₃ 3H ₂ O as the ruthenium compound, 2,6 as the tertiary amine
-A reaction was carried out in the same manner as in Example 1 using lutidine.

[Table] Comparative Example 1 Methanol 10 g (0.3121 mol), dicobalt octacarbonyl 2 g (5.8 mmol), ruthenium acetylacetate Ru (AA) ₃ 0.52 g (1.3 mmol), tri-n-butylphosphine 3 g (14.7 mmol) and 10 g (0.128 mol) of benzene were charged, and a reaction was carried out under the same conditions as in Example 1. The catalyst composition at this time is cobalt:ruthenium:phosphorus:nitrogen=1:0.11:1.28:0 (atomic ratio). As a result, when the methanol conversion rate was 24.25%, the ethanol selectivity was 68.6%, and the selectivity for other components was 0.15% dimethyl ether, 0.39% acetaldehyde, 2.31% methyl formate, 2.34% methyl ethyl ether, and 2.31% methyl acetate. , n-propanol 2.20%, and dimethoxyethane 4.50%. The actual methanol conversion rate at this time was 22.5%, and the achievable ethanol selectivity was 77.4%. This shows that the single combination of dicobalt octacarbonyl ruthenium acetylacetate and tertiary phosphine has low ethanol selectivity. Comparative Examples 2 to 5 Comparative Examples 2 to 5 corresponding to Example 1 are listed in Table 2. Comparative Example 2: It is shown that the ethanol selectivity is low when a tertiary amine is used alone in combination with a dicobalt octacarbonyl ruthenium acetylacetate system. Comparative Examples 3-4; Catalyst composition (Co:Ru:P:N)
is outside the specified range. It is shown that when the amount of tertiary amine added is small (Comparative Example 3), the effect is small, and when it is large (Comparative Example 4), the catalyst activity and selectivity to ethanol are reduced. Comparative Example 5: Iodine (I/
This corresponds to a five-component system catalyst consisting of cobalt, ruthenium, iodine, phosphorus, and nitrogen to which Co=1 atomic ratio) is added. Although the catalytic activity is improved by the addition of iodine, by-products such as methyl ethyl ether and methyl acetate are increased, indicating that the improvement in ethanol selectivity is small.

【table】

Claims (1)

[Claims] 1. When producing ethanol by reacting methanol, carbon monoxide and hydrogen, (1) 0.1 to 100 cobalt atoms per mole of methanol as a catalyst.
mg atoms of cobalt compounds, (2) Ruthenium atoms equivalent
A ruthenium compound having an amount of 0.05 to 50 mg, (3) a tertiary phosphine having an amount of 0.2 to 200 mg in terms of a phosphorus atom, and (4) a tertiary amine having an amount of 0.1 to 100 mg in terms of a nitrogen atom, and cobalt:ruthenium:phosphorus:nitrogen. A method for producing ethanol, which comprises maintaining the atomic ratio of 1:0.05 to 1:0.2 to 10:0.1 to 5 and carrying out the reaction in the absence of iodine.