JPS6347694B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for directly synthesizing ethanol from carbon monoxide and hydrogen (hereinafter referred to as synthesis gas). More specifically, the present invention relates to an improved method for directly synthesizing ethanol from synthesis gas by a liquid phase homogeneous catalytic reaction using ruthenium compounds and halogen compounds as catalysts.

Ethanol is a compound that has a wide range of uses as an intermediate raw material or solvent for various chemicals.

Problems to be Solved by the Prior Art and the Invention Synthesis gas containing carbon monoxide and hydrogen is continuously fed into a catalyst-containing liquid medium mainly composed of ruthenium compounds and halogen compounds held in a reactor. The present inventors have already filed an application for a method of producing ethanol by supplying ethanol to produce ethanol and taking out the produced ethanol along with unreacted synthesis gas (Japanese Patent Application Laid-open No. 218540/1983).
According to this method, a catalyst-containing liquid medium is held in a reactor, and ethanol is synthesized with this liquid medium. A part of the reaction heat generated in this synthesis reaction is offset by the heat of vaporization of the methanol or ethanol produced when the generated methanol or ethanol is accompanied by unreacted synthesis gas and exits the reactor system. This remaining reaction heat is dissipated through the walls of the reactor.

However, inside the reactor, a temperature gradient occurs between the center of reaction and the wall of the reactor, or between the bottom and top of the reactor. This temperature gradient changes with slight fluctuations in the amount of continuously supplied synthesis gas, making it difficult to control the reaction temperature. Additionally, when the reaction temperature is high or the catalyst concentration in the liquid medium is high, the reaction heat is greater than the heat dissipated through the walls of the reactor, causing the reaction to run out of control and making it difficult to produce stable ethanol. be.

An object of the present invention is to provide a method for continuously and stably producing ethanol from synthesis gas by solving the problems associated with the heat of reaction as described above.

Means for Solving the Problems The present inventors have made extensive studies to solve these problems. As a result, in the method of producing ethanol by supplying synthesis gas to the catalyst liquid held in the reactor, the boiling point at normal pressure is 20 to 150℃.
The inventors have discovered that ethanol can be stably produced by continuously supplying hydrocarbons to a reactor, leading to the present invention.

That is, the present invention continuously supplies synthesis gas containing carbon monoxide and hydrogen to a catalyst-containing liquid medium mainly composed of a ruthenium compound and a halogen compound held in a reactor to produce ethanol. In the method of producing ethanol by entraining the produced ethanol with unreacted synthesis gas and taking it out, the boiling point at normal pressure is 20 to 150.
This is a method for producing ethanol, characterized by continuously supplying hydrocarbons at a temperature of °C to a reactor.

Any ruthenium compound used in the present invention can be used as long as it forms a ruthenium complex having a carbon monoxide ligand under the reaction conditions. Examples of these include, in addition to ruthenium metal, ruthenium oxides such as ruthenium dioxide and ruthenium tetroxide, their hydrates, mineral salts of ruthenium such as ruthenium chloride, ruthenium iodide, and ruthenium nitrate, and ruthenium acetate. , organic acid salts of ruthenium such as ruthenium propionate.

Ruthenium compounds can also be used directly in the form of coordination compounds, examples of which include ruthenium carbonyl such as triruthenium dodecacarbonyl, ruthenium combined with oxygen,
Examples include ruthenium complexes and their salts coordinated with ligands containing sulfur, halogen, nitrogen, phosphorus, arsenic, antimony, bismuth, etc.

Among these ruthenium compounds, ruthenium oxide, ruthenium halide, ruthenium carbonyl, and ruthenium complexes in which at least some of the carbon monoxide ligands of ruthenium carbonyl are replaced with other ligands are preferred.

Further, in the method of the present invention, it is necessary to use a halogen compound as a promoter for the ruthenium compound. In the absence of these halogen compounds, ethanol activity and selectivity are significantly lower.

These halogen compounds include metal salts such as alkali metal salts and alkaline earth metal salts having halogen ions such as chloride ions, bromide ions, and iodine ions as anions constituting the salts;
Examples include salts such as ammonium salts, quaternary phosphonium salts, and iminium salts, and hydrocarbon halides such as alkyl halides and aryl halides. Further, hydrogen halides, acid halides, transition metal halides, and the like can also be used. More specifically, examples of metal salts include lithium chloride, lithium bromide, lithium iodide, sodium chloride, potassium bromide, cesium iodide, magnesium chloride, and lanthanum iodide; examples of ammonium salts include trimethylammonium Quaternary phosphonium salts such as chloride, trimethylammonium bromide, trimethylammonium iodide, dimethylethylammonium chloride, methyldiethylammonium iodide, tetramethylammonium chloride, tetramethylammonium iodide, tetraphenylammonium chloride, cetyltriethylammonium bromide, etc. Examples include tetraphenylphosphonium chloride, tetra n-butylphosphonium bromide,
Examples of iminium salts include bis(triphenylphosphine)iminium chloride, bis(triphenylphosphine)iminium bromide, such as n-hebutyltriphenylphosphonium bromide, benzyltriphenylphosphonium iodide, and methyltriphenylphosphonium chloride. Examples of alkyl halides include methyl chloride, bis(triphenylphosphine)iminium iodide, and iminium salts in which at least a portion of the phenyl group of these iminium compounds is substituted with a methyl group, ethyl group, etc. methylene chloride, chloroform, carbon tetrachloride, methyl iodide,
Examples of hydrogen halides include hydrogen chloride, hydrogen bromide, and hydrogen iodide; examples of acid halides include acetyl chloride and acetyl bromide; and transition metals such as acetyl chloride and acetyl bromide. Examples of halides include nickel chloride, ruthenium chloride, and copper iodide.

These halogen compounds can be used alone or in combination of two or more.

In the method of the present invention, the amount of these halogen compounds used per gram atom of ruthenium is:
The halogen atoms range from 0.1 to 200 gram atoms, more preferably from 1 to 20 gram atoms.

The method of the invention is carried out in a liquid medium. The liquid medium used is preferably an aprotic liquid solvent. In protic liquid media such as water and alcohol, the ethanol production activity is low and the selectivity is also poor.

In the method of the present invention, examples of the aprotic liquid solvent preferably used include decalin,
Saturated hydrocarbons and aromatic hydrocarbons such as tetralin and diurene, halogenated hydrocarbons such as chloropentane, o-dichlorobenzene, p-chlorotoluene, and fluorobenzene, dioxane, tetrahydrofuran, ethyl ether, anisole,
Ethers such as phenyl ether, diglyme, tetraglyme, 18-crown-6, esters such as methyl acetate, ethyl butyrate, methyl benzoate, γ-butyrolactone, ketones such as acetone, acetophenone, benzophenone, N-methyl Pyrrolidin-2-one, N-ethylpyrrolidin-2-one, N,N-dimethylacetamide,
N-substituted amides such as N-methylpiperidone and hexamethylphosphoric triamide, N,N-
Tertiary amines such as diethylaniline, N-methylmorpholine, pyridine, and quinoline, sulfones such as sulfolane, sulfoxides such as dimethylsulfoxide, urea derivatives such as 1,3-dimethyl-2-imidazolidinone, and , phosphine oxides such as tributylphosphine oxide, and silicone oil.

Among these, particularly preferred liquid solvents include saturated hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, ethers, and phosphine oxides.

The liquid solvent used in the method of the present invention is more preferably a liquid solvent having a boiling point of 200° C. or higher under normal pressure in order to minimize volatilization from the reactor. However, even if the boiling point is below 200°C, it can be separated from the product and recycled to the reactor for use.

These liquid solvents can be used alone or in combination of two or more.

Further, if the liquid solvent used in the method of the present invention is liquid at least under the reaction conditions,
It can be used even if it is solid at room temperature and pressure.

Hydrocarbons with a boiling point of 20 to 150°C at normal pressure used in the method of the present invention include, for example, saturated hydrocarbons such as pentane, 2-methylbutane, hexane, 2-methylpentane, 2,3-dimethylbutane, heptane, and octane. Examples include hydrocarbons, cyclic saturated hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, and ethylcyclohexane, and aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene.

These hydrocarbons can be used alone or in combination of two or more.

"In the process of the present invention, the feed rate of these hydrocarbons ranges from 1 to 1000 grams, more preferably from 10 to 1000 grams per hour per liter of reaction volume.
It is in the range of 300 grams. In the method of the present invention, the reaction temperature is in the range of 160°C to 300°C, preferably in the range of 180 to 260°C.

At reaction temperatures below 160°C, the reaction between carbon monoxide and hydrogen is extremely slow. Furthermore, when the reaction temperature exceeds 300°C, the amount of methane by-product increases significantly, and the selectivity of ethanol decreases.

Moreover, the reaction pressure is in the range of 150 to 800 Kg/cm ² , preferably in the range of 300 to 500 Kg/cm ² . The higher the reaction pressure, the better the reaction between carbon monoxide and hydrogen.
Practical pressure is preferably 800 Kg/cm ² or less.

The raw materials used in the method of the present invention are carbon monoxide and hydrogen. Synthesis gas is usually used. The unreacted synthesis gas that is taken out along with the produced ethanol is the remaining gas that was supplied to the reactor and was mainly consumed in the production of ethanol, and of course contains small amounts of by-product carbon dioxide and methane. This gas strips the ethanol produced at the same time.

The supplied gas may be a mixture of gases that are inert to the reaction. By mixing an inert gas in this manner, the stripping effect of ethanol can be improved.

As such a gas, an inert gas such as nitrogen, argon, helium, etc. is used.

The range of gas space velocity of the gas supplied to the reactor is not particularly limited. The optimum gas hourly space velocity is determined by the reactor configuration, reaction temperature, reaction pressure, catalyst performance, etc.

It is not preferable if the space velocity is too large or too small. If the space velocity is too large, the flow state of the synthesis gas relative to the catalyst liquid becomes a circular flow, which adversely affects the reaction. Furthermore, this has the undesirable effect of causing the catalyst liquid to scatter outside the reactor as mist. Also, if the space velocity is too low, the amount of product entrained in the gas will be reduced, reducing stripping efficiency.

The method of the present invention will be specifically explained with reference to the drawings.
FIG. 1 is a manufacturing process diagram for carrying out the method of the present invention.

In FIG. 1, a reactor 1 holds a liquid medium containing a ruthenium compound and a halogen compound. Synthesis gas is fed to reactor 1 through conduit 6 and hydrocarbons through conduit 10.
In the reactor 1, the reaction temperature is in the range of 180°C and 260°C, and the reaction pressure is in the range of 300 to 600 kg/cm ² . Synthesis gas continuously supplied to such a reactor 1 contacts a catalyst in a liquid medium to produce ethanol.

The produced ethanol and the co-produced by-products are entrained by the synthesis gas flowing unreacted in the liquid medium and are led through conduit 7 to cooler 2 .

Here the ethanol and by-products are cooled and
The high-pressure gas-liquid separator 3 separates the gas into non-condensable gas and condensed liquid. The gas phase led to conduit 8 is accompanied by a small amount of products such as methanol. On the other hand, the liquid phase is led to conduit 9. The gas introduced into conduit 8 and the liquid introduced into conduit 9 are taken out through pressure reducing valves 4 and 5, respectively.

Function The present invention further provides a method for flowing raw material synthesis gas through a liquid medium containing a catalyst held in a reactor;
Continuously supplies hydrocarbons with a boiling point of 20 to 150℃,
The heat of evaporation reduces the reaction heat and maintains the reaction temperature stably.

According to this method, temperature gradients within the reactor are reduced. It also has the advantage that temperature control becomes easy. Furthermore, the used hydrocarbons can be recovered at the reactor outlet and used again.

That is, the present invention is a more stable method for producing ethanol than conventional methods.

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

Example 1 28 mg atoms of triruthenium dodecacarbonyl (Ru3(CO)12) as Ru, 140 mmol of bis(triphenylphosphine)iminium bromide (Ph3P)2NBr), 84 mmol of phosphoric acid, and 560 g as liquid solvent of tri-n-butylphosphine oxide in a tubular reactor (diameter 4 cm, length
120 cm) from the bottom, and after closing the reactor, temperature increase was started when the pressure of the reactor reached 345 Kg/cm ² . When the reactor temperature reached 240℃ (the reactor pressure at this time was 450Kg/ ^cm2 ), xylene was
The reaction was carried out by continuously supplying synthesis gas from the bottom of the reactor at a rate of 30 g/hour, while maintaining the gas hourly space velocity of synthesis gas at 2500/hour and the reaction pressure at 450 Kg/cm ² .

Average of 105 per hour from the gas at the reactor outlet
g of liquid was collected.

As a result of analyzing the liquid with a gas chromatograph, the following results were obtained.

Methanol 29.9g Ethanol 33.2g Propanol 2.4g Formic acid 1.3g Acetic acid 2.3g Acetaldehyde 4.9g Xylene 29.6g During this reaction, the temperature fluctuation at 50 cm from the bottom of the reactor was 240±3°C.

Furthermore, the temperature difference between 25 cm and 50 cm from the bottom of the reactor was 8°C.

Comparative Example 1 A reaction was carried out in the same manner as in Example 1, but xylene was not supplied.

An average of 75g per hour from the gas at the reactor outlet
The liquid was collected.

The results of the analysis were as follows.

Methanol 30.1g Ethanol 31.7g Propanol 1.8g Formic acid 1.5g Acetic acid 2.7g Acetaldehyde 5.7g During this reaction, the temperature fluctuation at 50 cm from the bottom of the reactor was 240±15°C. Furthermore, the temperature difference between 25 cm and 50 cm from the bottom of the reactor was 25°C.

Example 2 In Example 1, benzene was supplied at a rate of 40 g/hour instead of xylene, and the reaction temperature was changed.
The reaction was carried out in the same manner except that the temperature was changed to 250°C.

Average of 130 per hour from the gas at the reactor outlet
g of liquid was collected. The analysis results were as follows.

Methanol 36.5g Ethanol 42.3g Propanol 3.8g Formic acid 1.5g Acetic acid 2.9g Acetaldehyde 2.3g Benzene 40.2g During this reaction, the temperature fluctuation at 50 cm from the bottom of the reactor was 240±8°C.

Furthermore, the temperature difference between 25 cm and 50 cm from the bottom of the reactor was 15°C.

Comparative Example 2 As a result of carrying out the reaction in the same manner as in Example 1 without supplying benzene, the reaction ran out of control and temperature control became impossible.

Effects In Comparative Example 1, the temperature fluctuation at 50 cm from the bottom of the reactor was 15°C, whereas in the example it was 3°C. Further, the temperature difference within the reactor was 2°C in Comparative Example 1, whereas it was 8°C in Example 1.

Further, in Comparative Example 2, the reaction ran out of control and temperature control was impossible, whereas in Example, it was possible to suppress temperature fluctuations to 8° C. by supplying benzene.

As described above, by using the method of the present invention, it is possible to reduce the temperature difference inside the reactor, and it is also possible to easily control the temperature of the reaction and to stably produce ethanol.

[Brief explanation of the drawing]

FIG. 1 shows an example of a manufacturing flow sheet for carrying out the method of the present invention. In the figure, each symbol is as follows. 1... Reactor, 2... Cooler, 3... High pressure gas-liquid separator, 4, 5... Pressure reducing valve.

Claims (1)

[Claims] 1. Synthesis gas containing carbon monoxide and hydrogen is continuously supplied to a catalyst-containing liquid medium mainly composed of a ruthenium compound and a halogen compound held in a reactor to produce ethanol. In the method of producing ethanol by extracting ethanol along with unreacted synthesis gas,
Hydrocarbons with a boiling point of 20 to 150°C at normal pressure are added at a rate of 10 to 150°C per liter of reactor volume per hour.
A method for producing ethanol, characterized by continuously feeding it into a 300 gram reactor.