JPS62158229A - Production of ethanol - Google Patents

Abstract

PURPOSE:In directly synthesizing ethanol from a synthesis gas by a liquid-phase, homogeneous catalytic reaction using a ruthenium compound and a halogen compound as a catalyst, to carry out the reaction stably and continuously, by successively feeding a hydrocarbon having a specific boiling point. CONSTITUTION:In producing ethanol by continuously feeding a synthesis gas containing carbon monoxide and hydrogen to a liquid medium containing a catalyst comprising a ruthenium compound and a halogen compound as main components put in a reactor, a hydrocarbon having 20-150 deg.C boiling point at normal pressure, such as pentane, 2-methylbutane, cyclopentane, benzene, toluene, etc., is continuously fed to the reactor, temperature gradient in the reactor is lessened and temperature is readily controlled to produce ethanol stably. The hydrocarbon used is recovered at the outlet of the reactor and can be reused.

Description

DETAILED DESCRIPTION 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 one 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.

into a catalyst-containing liquid medium mainly composed of ruthenium compounds and nitrogen compounds held in the reactor.

The present inventor has developed a method for producing ethanol by continuously supplying synthesis gas containing carbon monoxide and hydrogen to produce ethanol, and extracting the produced ethanol along with unreacted synthesis gas. have already filed an application (Japanese Patent Application No. 1988-57544. Application date: March 23, 1985).

According to this method.

A reactor holds a catalyst-containing liquid medium in which ethanol is synthesized. A part of the reaction heat generated in this synthesis reaction is entrained by the generated methanol or ethanol and unreacted synthesis gas.

They are offset by the heat of vaporization of methanol or ethanol as they exit 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 has the disadvantage that a small change in the amount of continuously supplied synthesis gas causes the ratio to change, making it difficult to control the temperature within one reactor degree. Also, if the degree of 1 reactor is high,
Furthermore, if the catalyst concentration in the liquid medium is high, the heat of reaction is greater than the heat dissipated through the wall of the reactor, and one reaction is on the verge of going out of control, making it difficult to produce stable ethanol.

The object of the present invention is to solve the problems associated with the heat of reaction as described above, and to continuously produce ethanol from one synthesis gas.

Moreover, it provides a stable manufacturing method.

Means for Solving the Problems The present inventors have conducted extensive studies to solve these problems. As a result, in a method for producing ethanol by supplying synthesis gas to a catalyst liquid held in a reactor, stable The present invention was based on the discovery that ethanol can be produced using the following method.

That is, the present invention continuously supplies a 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 co-producing the produced ethanol with unreacted synthesis gas and extracting it, the boiling point at normal pressure is 2.
This is a method for producing ethanol, characterized by continuously supplying hydrocarbons at a temperature of 0 to 150°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 one reaction condition. Examples of these include, in addition to ruthenium metal, ruthenium oxides such as ruthenium dioxide and ruthenium tetroxide;
These aqueous phase substances, ruthenium chloride, ruthenium iodide,
Examples include ruthenium mineral salts such as ruthenium nitrate, and organic ruthenium salts such as ruthenium acetate and 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, sulfur, halogen, nitrogen,
Phosphorus, arsenic, antimony.

Examples include ruthenium complexes coordinated with ligands such as bismuth, and their salts.

Among these ruthenium compounds, ruthenium? lJ
Preferred are ruthenium compound, ruthenium carbonyl, or a ruthenium complex in which at least some of the carbon monoxide ligands of ruthenium carbonyl are replaced with other ligands.

In addition, in the method of the present invention, it is necessary to use a rogen compound as a cocatalyst in addition to the ruthenium compound. In the absence of these 710 gene compounds, ethanol activity and selectivity are significantly lower.

Examples of these halogen compounds include metal salts such as alkali metal salts and alkaline earth metal salts having halogen ions such as chloride ions, odor 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 iodine, sodium chloride, potassium bromide, cesium iodide, magnesium chloride, and lanthanum iodide.

Diethylammonium iodide, tetramethylammonium chloride, tetramethylammonium iodide, tetraphenylammonium chloride 1. Cetyltriethylammonium bromide etc. 1, ■ 4th
Examples of class phosphonium salts include tetraphenylphosphonium chloride, tetra-n-fluorphosphonium bromide, n-hebutyltriphenylphosphonium bromide, and benzyltriphenylphosphonium iodide.

Methyltrinoenylphosphonium chloride, etc.

■ Examples of iminium salts include bis(triphenylphosphine)iminium chloride, bis(triphenylphosphine)iminium bromide, bis(triphenylphosphine)iminium iodide, and these iminium f-hybrid compounds with less phenyl groups. Examples of alkyl rogenides include iminium salts partially substituted with methyl or ethyl groups, such as methyl chloride, methylene chloride,
Chloroform, carbon tetrachloride, methyl iodide, ethyl iodide, salts (B benzyl, benzyl iodide, ■ Examples of hydrogen halides, such as hydrogen chloride, hydrogen bromide, hydrogen iodide, etc., and ■ acids), rogens Examples of such compounds include acetyl chloride and acetyl bromide. Examples of transition metal 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 is per gram atom of ruthenium.

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, an example of the aprotic liquid solvent preferably used is decalin.

Saturated and aromatic hydrocarbons such as tetralin, durene, chloropentane, 0-dichlorobenzene, p
-Halogenated hydrocarbons such as chlorotoluene, fluorobenzene, dioxane, tetrahydrofuran, ethyl ether, anisole.

Phenyl ether, diglyme, tetraglyme.

Ethers such as 18-crown-6, methydiacetate,
Esters such as ethyl butyrate, methyl benzoate, r-butyrolactone, ketones such as acetone, acetophenone, benzophenone, N-methylpyrrolidin-2-one, N-ethylpyrrolidin-2-one, N,N-dimethylacetamide, N-substituted amides such as N-methylpiperidone, hexamethylphosphoric triamide, N,N
- Tertiary amines such as diethylaniline, N-methylmorpholine, pyridine, and quinoline; sulfones such as sulfolane; sulfoxides such as dimethyl sulfoxide; and urea derivatives such as 3-dimethyl-2-imidazolidinone; , phosphine oxides such as tributylphosphine oxide, and silicone oil.

Among these, particularly preferred liquid solvents are saturated hydrocarbons, aromatic hydrocarbons, and halogenated hydrocarbons.

Examples include ethers and phosphine oxytos.

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 less than 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.

In addition, the amount of liquid solvent used in the method of the present invention is small (
If both are liquid under the reaction conditions.

It can be used even if it is solid at room temperature and pressure.

The boiling point at normal pressure used in the method of the present invention is 2
Examples of hydrocarbons having a temperature of 0 to 150°C include:

Saturated hydrocarbons such as pentane, 2-methylbutane, hexane, 2-methylpentane, 2.3-dimethylbutane, heptane, octane, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, xane, ethylcyclohexane, etc.) cyclic saturated carbonization Examples include hydrogen, aromatic hydrocarbons such as henzene, toluene, ethylbenzene, and xylene.

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

“In the process of the invention, the feed rate of these hydrocarbons is 1 to 100 per liter of reaction volume per hour.
0 grams, more preferably 10-300 grams. In the method of the present invention, the degree of one reaction is in the range of 160°C to 300°C, preferably in the range of 180 to 260°C.

When the reaction temperature is below 160°C, the reaction between carbon monoxide and hydrogen is extremely slow. Also, if the degree of one reaction exceeds 300℃,
Methane by-product increases significantly and ethanol selectivity decreases.

Moreover, one reaction pressure is in the range of 150 to 800 ke/c+1.

Preferably it is in the range of 300 to 500 ks/d.

Although a higher reaction pressure is preferable for the reaction of carbon monoxide and hydrogen, a practical pressure of 800 k+I/d or less is preferable.

The raw materials used in the method of the present invention are carbon monoxide and hydrogen. Usually 1 synthesis gas is used. Unreacted synthesis gas, which is taken out along with the produced ethanol, is supplied to one reactor, and is mainly the remaining gas consumed in the production of ethanol, and of course contains a small amount of by-product carbon dioxide and methane. This gas strips out the ethanol produced at the same time.

The supplied gas may be mixed with a gas inert to the reaction.

By mixing an inert gas in this way, 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 the 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 type, reaction source degree, reaction pressure, catalyst and performance, etc.

Space velocity is not preferable if it 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. Also,
Furthermore, the catalyst liquid scatters outside the reactor as a mist, which is an undesirable effect. 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, one reactor (1) holds a liquid medium containing a ruthenium compound and a rogen compound. Synthesis gas is fed through line (6) and hydrocarbons through line (lO) to one reactor (1). Reactor (
In 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/-.

Synthesis gas continuously fed into such a reactor (1) contacts a catalyst in a liquid medium to produce ethanol.

The produced ethanol and co-produced by-products are entrained in the liquid medium by the unreacted syngas flowing through the conduit (
7) and then into the cooler (2).

Here, the ethanol and by-products are cooled and separated into non-condensable gas and condensate in a high-pressure gas-liquid separator (3). A small amount of products such as methanol is entrained in the gas phase led to the conduit (8). On the other hand, the liquid phase is led to the conduit (9). The gas introduced into the conduit (8) and the liquid introduced into the conduit (9) are taken out through the pressure reducing valve (4) and the pressure reducing valve (5), respectively.

Operation The present invention further comprises flowing raw synthesis gas through a liquid medium containing a catalyst held in a reactor.

A hydrocarbon having a boiling point of 20 to 150° C. is continuously supplied, and the reaction heat is reduced by its heat of vaporization to maintain a stable reaction temperature.

This method reduces the temperature gradient within one reactor. It also has the advantage that temperature control becomes easy. Also,
The used hydrocarbons can be recovered at the reactor outlet and used again.

That is, 1. The present invention is a method for producing ethanol that is more stable than the conventional method. 6 Examples The method of the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example I 28 ■ atoms of triruthenium dodecacarbonyl (Ru 3 (Co) 12) as Ru, 140 mmol of bis(triphenylphosphine)iminium bromide (P
h3P)2NBr), 84 mmol of phosphoric acid, and 5609 trilobylphosphine oxide as a liquid solvent in a tubular reactor (diameter 4 cr,
After closing one reactor (length 120 Cal) from the bottom, heating was started when the pressure of one reactor reached 345 kg/cd. When the temperature of the reactor reached 240°C (the pressure of the reactor at this time was 450 kg/d), xylene was continuously supplied from the bottom of the reactor at 30 g/hour, and one synthesis gas was added. Space velocity 2500/hour1
The reaction was carried out while maintaining the reaction pressure at 450/cJ.

An average of 105 Da of liquid was taken from the reactor outlet gas per hour.

The results of analyzing the liquid using a gas chromatograph.

The following results were obtained: Methanol 29.1 F Ethanol 33.21 Propertool 2.4 g Formic acid 1.3 g Acetic acid 2.3 g Acetaldehyde 4.91 Xylene 29.6 The temperature was 240±3°C.

Moreover, the temperature difference between 251 and 50 CIm from the bottom of one reactor was 8°C.

Comparative Example 1 A reaction was carried out in the same manner as in Example 1, but no xylene was supplied.

An average of 759 liquids were taken from the reactor outlet gas per hour.

The results of the analysis were as follows.

Methanol 30.1F Ethanol 31.7 Dapropanol 1.8F Formic acid 1.51 Acetic acid 2.71 Acetaldehyde 5.7F During this reaction, the temperature fluctuation from the bottom of the reactor to 50C11 was 240±15°C. Also.

The temperature difference between 25CII+ and 500 m from the bottom of the reactor was 25°C.

Example 2 In Example 1, 40g of benzene was used instead of xylene.
The reaction was carried out in the same manner except that the reaction temperature was changed by 250° C./hour.

An average of 130 Da of liquid was taken per hour from the gas at the reactor outlet. The results of one analysis were as follows.

Methanol 36.5F Ethanol 42.39 Propertool 3.8g Formic acid 1.51 Acetic acid 2.9g Acetaldehyde 2.39 Benzene 40.29 During this reaction, the temperature fluctuation from the bottom of the reactor to 50cI+ was 240±8°C.

Moreover, the temperature difference between 251 cm and 50 cm from the bottom of one reactor was 15°C.

Comparative Example 2 A reaction was carried out in the same manner as in Example 1 without supplying benzene. As a result, one reaction went out of control and temperature control became impossible.

In Comparative Effect Example 1, the temperature fluctuation at 50 c+m from the bottom of the reactor was 15°C, whereas in Example 1 it was 3°C. Further, the temperature difference within one reactor was 25°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 2, 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 one reactor, and it is also possible to easily control the temperature of the reaction and to stably produce ethanol.

[Brief explanation of drawings]

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. ■ Reactor, 2 Cooler,

Claims (1)

[Claims] 1) Continuously supplying 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. A method for producing ethanol by removing ethanol along with unreacted synthesis gas, the method comprising continuously supplying a hydrocarbon having a boiling point of 20 to 150°C at normal pressure to a reactor. .