JPS63145244A - Production of ethanol - Google Patents

Abstract

PURPOSE:To produce ethanol by using an Ru compound or an Ru compound and a Co compound as a main catalyst and contacting synthesis gas with the catalyst under high temperature and pressure condition, wherein CO2 is supplied to a reactor in a manner to keep partial pressure of CO2 at the outlet of the reactor to a level higher than a specific level. CONSTITUTION:A liquid medium containing an Ru compound or an Ru compound and a Co compound as main catalyst and a halogen compound as a cocatalyst is made to contact with synthesis gas at 180-260 deg.C under 300-600kg/cm<2> pressure to produce an oxygen-containing compound and the reaction product is separated into noncondensed gas and a liquid phase containing condensed liquid with a cooler and a gas-liquid separator. In the above ethanol-production process, CO2 is supplied to the reactor in a manner to keep the partial CO2 pressure to >=A/B/C atm at the outlet of the reactor, wherein A (l/hr) is volume of by-produced CO2, B (l/kg/atm) is amount of soluble CO2 in 1kg of the liquid phase at the operation temperature of the gas-liquid separator and C (kg/hr) is amount of the liquid phase to be taken out of the gas-liquid separator. The decarbonation apparatus can be eliminated in the process.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for synthesizing ethanol directly from synthesis gas, i.e. carbon oxide and hydrogen. 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 a ruthenium compound or a ruthenium compound and a cobalt compound as the main catalyst.

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

(Counting Points to be Solved by the Prior Art and the Invention) Many methods have been proposed for directly synthesizing ethanol from synthesis gas using a liquid phase homogeneous catalyst of a ruthenium compound. For example, a method for directly producing methanol, ethylene glycol, and ethanol or their carboxylate derivatives by reacting synthesis gas in an appropriate solvent containing a solubilized ruthenium carbonyl complex (JP-A-55
-115834). Furthermore, a method for selectively producing methanol and ethanol by contacting a homogeneous ruthenium catalyst, a halogen or a halogenation promoter, and an organic oxidized phosphine compound with synthesis gas (Japanese Patent Laid-Open No. 57-8232
No. 7).

In these methods, the addition rate of synthesis gas in one bath in the reactor is more than 10%, and therefore unreacted synthesis gas is recycled to the reactor and used repeatedly. Since by-product carbon dioxide accumulates in this unreacted synthesis gas recycling system, the carbon dioxide in the unreacted synthesis gas that is constantly recycled is replaced with a potassium carbonate aqueous solution or ethanolamine. It is necessary to decarboxylate by treating with an alkaline solution such as 8 liquid. However, the impact on the economics of the decarboxylation device or process liquid is significant.

Thus, in order to industrially produce ethanol, an economical method for processing carbon dioxide is required.

An object of the present invention is to solve the economic problems associated with the method of treating accumulated carbon dioxide and to provide a method for economically producing ethanol.

(Means for Solving the Problems) The present inventors have conducted intensive studies on an economical method for removing carbon dioxide from the reaction system. As a result, it was found that in a liquid phase homogeneous catalytic reaction using a ruthenium compound or a ruthenium compound and a cobalt compound as the main catalyst, there is a significant difference in the solubility of carbon dioxide and synthesis gas in the liquid phase in a gas-liquid separator. Furthermore, by applying this, carbon dioxide is supplied to the reactor, the partial pressure of carbon dioxide at the reactor outlet is increased, and most of the carbon dioxide by-produced in the reactor is dissolved in the liquid phase in the gas-liquid separator, resulting in a reaction. The present inventors have discovered that the method of removing carbon dioxide from the system eliminates new accumulation of carbon dioxide in the recycled gas and eliminates the need for a decarboxylation device, leading to the completion of the present invention.

That is, the present invention involves bringing synthesis gas into contact with a ruthenium compound and a halogen compound, or a liquid medium containing a ruthenium compound, a cobalt compound, and a halogen compound under high temperature and pressure to generate oxygen-containing compounds such as methanol and ethanol, and reacting. In a method for producing ethanol by cooling it to below the reaction temperature using a cooler and a gas-liquid separator installed at the outlet of the reactor and separating it into a liquid phase containing a non-pseudocondensable gas and a condensate, one of the by-produced carbon dioxide The amount of carbon dioxide produced per hour is A (1/hr), and the amount of carbon dioxide dissolved in 1 kg of liquid phase at the operating temperature of the gas-liquid separator is BC1/kg/
If the amount of liquid phase taken out from the gas-liquid separator per hour is C (kg/hr), then maintain the partial pressure of carbon dioxide at the reactor outlet above the formula A/B/C (atmospheric pressure). The ruthenium compound used in the method of the present invention is one that forms a complex having carbon monoxide coordination under the reaction conditions. If so, you can use either one. Examples of these include, in addition to metal ruthenium, ruthenium oxides such as ruthenium dioxide and ruthenium tetroxide, their hydrates, mineral acid salts of ruthenium such as ruthenium chloride, ruthenium iodide, and ruthenium nitrate, ruthenium acetate,
Examples include 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, and ruthenium combined with oxygen, sulfur, halogen, nitrogen, phosphorus,
Examples include ruthenium complexes coordinated with ligands containing arsenic, antimony, bismuth, etc., and their salts.

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

The amount of ruthenium compound used in the method of the invention in the liquid medium, expressed as weight in terms of ruthenium metal, is
Liquid medium 1000! It ranges from 0.1 to 300 parts by weight per i part.

In addition to metal cobalt, cobalt compounds include cobalt oxide, cobalt hydroxide, cobalt chloride, cobalt iodide, cobalt mineral salts such as cobalt nitrate, cobalt acetate, cobalt benzoate, and cobalt naphthenate. These include organic acid salts of cobalt. Additionally, coordination compounds can also be used, such as cobalt carbonyls such as dicobalt octacarbonyl, tetracobalt dodecacarbonyl, cyclopenkungenyl cobalt dicarbonyl; Examples include cobalt complexes and their salts coordinated with ligands containing oxygen, sulfur, halogen, nitrogen, phosphorus, arsenic, antimony, bismuth, etc. Among these cobalt compounds, cobalt oxides, cobalt halides,
Preferable examples include cobalt carbonyl, cobalt organic acid salts, cobalt acetylacetonate, and cobalt complexes in which at least some of the carbon monoxide ligands of cobalt carbonyl are replaced with other ligands.

The amount of cobalt compound used in the process of the invention in the liquid medium ranges from 0 to 100 gram atoms, preferably from 0 to 10 gram atoms of cobalt per gram atom of ruthenium. Furthermore, in the method of the present invention,
It is necessary to use a halogen compound as a promoter for the ruthenium compound and the cobalt 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, alkaline earth metal salts, ammonium salts, quaternary Examples include salts such as 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, (1) examples of metal salts include lithium chloride, lithium bromide, lithium iodide, sodium chloride, potassium bromide, cesium iodide, magnesium chloride, lanthanum iodide, etc.; (2) ammonium salts; Examples include trimethylammonium chloride, trimethylammonium bromide, trimethylammonium iodide, dimethylethylammonium chloride,
Methyldiethylammonium iodide, tetramethylammonium chloride, tetramethylammonium iodide, tetraphenylammonium chloride, cetyltriethylammonium bromide, etc. (3
) Examples of quaternary phosphonium salts include tetraphenylphosphonium chloride, tetra-n-butylphosphonium bromide, n-hebutyltriphenylphosphonium bromide, benzyltriphenylphosphonium iodide, methyltriphenylphosphonium chloride, etc. (4) iminium salts Examples include bis(triphenylphosphine)iminium chloride, bis(triphenylphosphine)iminium bromide, bis(triphenylphosphine)iminium ioguide, and at least a portion of the phenyl groups of these iminium compounds are methyl groups. and iminium salts substituted with ethyl groups, etc. (5)
Examples of alkyl halides include methyl chloride, methylene chloride, chloroform, carbon tetrachloride, methyl iodide, ethyl iodide, benzyl chloride, benzyl iodide, etc. (6)
Examples of hydrogen halides include hydrogen chloride, hydrogen bromide, hydrogen iodide, and (7) examples of acid halides.
Examples of the (8) transition metal halides include acetyl chloride and acetyl bromide, as well as nickel chloride, ruthenium chloride, and copper iodide.

Moreover, iodine, chlorine gas, and bromine gas can also be used.

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 in the range of 0.1 to 200 gram atoms of halogen per 1 gram atom of ruthenium, more preferably 1 to 200 gram atoms.
In the 50 gram atom range.

The method of the invention is carried out in a liquid medium. The liquid medium used is preferably an aprotic liquid solvent.

For example, saturated and aromatic hydrocarbons such as heptane, octane, cyclohexane, decalin, tetralin, kerosene, benzene, toluene, xylene, durene, hexamethylbenzene, chlorobencune, 0-dichlorobenzene, p-chlorotoluene, fluorocarbons, etc. Halogenated hydrocarbons such as benzene, dioxane, tetrahydrofuran, ethyl ether, anisole, phenyl ether,
Ethers such as diglyme, tetraglyme, 18-crown-6, ester necks such as methyl acetate, ethyl butyrate, methyl benzoate, T-butyrolactone, acetone,
Ketones such as acetophenone and benzophenone, N-
Methylpyrrolidin-2-one, N-ethylpyrrolidine-
N-substituted amides such as 2-one, N, N-dimethylacetamide, N-methylpiperidone, hexamethylphosphoric triamide, N, N-diethylaniline,
Tertiary amines such as N-methylmorpholine, pyridine, and quinoline, sulfones such as sulfolane, sulfoxides such as dimethylsulfoxide, urea derivatives such as 1,3-dimethyl-2-imidazolidinone, and triethylphosphine. oxide, tri-n-propylphosphine oxide, tri-n-butylphosphine oxide, tri-n-hebutylphosphine oxide, tri-n-octylphosphine oxide, triphenylphosphine oxide, tri-p-)lylphosphine oxide, tri-p-chlorophenylphosphine oxide , oxides of trivalent organic phosphorus compounds such as tributylphosphine oxide, and silicone oil.

Among these, particularly preferred liquid solvents include saturated hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, ethers, and oxides of trivalent organic phosphorus compounds.

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

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

In the method of the present invention, the reaction temperature is in the range of 160 to 300°C, preferably in the range of 180 to 260''C. If the reaction temperature is less than 160°C, the reaction between carbon monoxide and hydrogen is extremely slow. When the reaction temperature exceeds 300°C, the by-product of carbon dioxide increases significantly and the selectivity of ethanol decreases.

In addition, the reaction pressure is in the range of 150 to 800 kg/c+l, preferably in the range of 300 to 600 kg/d.
Although the higher the reaction pressure is, the more preferable it is for the reaction of carbon oxide and hydrogen, the practical pressure is preferably 800 kg/c+a or less.

By selecting the reaction conditions, it is possible to carry out the method of the present invention even when using pure hydrogen in the presence of carbon dioxide. Further, other components inert to the present invention, such as nitrogen and methane, may be present in the raw material synthesis gas.

In the method of the present invention, a method for cooling the reactor to a temperature below the reaction temperature using a cooler and a gas-liquid separator installed at the outlet of the reactor and separating it into a liquid phase containing a non-condensable gas and a condensed liquid is known to those skilled in the art. This is done by a known method.

At this time, when the cooling temperature is lower, the amount of carbon dioxide dissolved in the condensate increases, while the amount of hydrogen and carbon monoxide dissolved in the liquid phase decreases. Therefore, the lower the cooling temperature is, the more preferable it is, but when cooling costs are considered, a range of 15 to 100°C is practically preferable.

In the method of the present invention, the amount of by-product carbon dioxide produced per hour A (42/hr) is when the reaction is carried out using the catalyst used in the method of the present invention without supplying carbon dioxide to the reactor. The amount of carbon dioxide produced in O″C11C
The pressure was 11 atm.

In the method of the present invention, the amount of carbon dioxide dissolved in 1 kg of liquid phase at the operating temperature of the gas-liquid separator (Bl/kg/atmosphere)
is the solubility of carbon dioxide in the liquid phase of the gas-liquid separator obtained in the reaction using the catalyst used in the method of the present invention, measured at the operating temperature of the gas-liquid separator and converted to 0 ° C and 11 atm. It is a value.

This solubility is measured in a conventional manner. For example, there is a method in which the liquid phase obtained by the reaction is placed in an autoclave, carbon dioxide is injected under pressure, and after stirring for a predetermined period of time, a portion of the liquid phase is extracted and its weight and amount of gas generated are measured. .

In the method of the present invention, the amount of liquid phase taken out from the gas-liquid separator per hour C (kg/hr) refers to the amount of liquid phase C (kg/hr) taken out from the gas-liquid separator when the reaction is carried out using the catalyst used in the method of the present invention and without supplying carbon dioxide to the reactor. It is the weight per hour of the liquid phase containing the condensate that is separated in the gas-liquid separator when carried out.

In the method of the present invention, the partial pressure of carbon dioxide at the reactor outlet is expressed by the formula A
Carbon dioxide is supplied to the reactor so that the pressure is equal to or higher than /B/C (atmospheric pressure).

The method of the present invention will be specifically explained with reference to the drawings.

In FIG. 1, a reactor (1) holds a ruthenium compound and a halogen compound, or a liquid solvent containing a ruthenium compound, a cobalt compound, and a halogen compound. The raw synthesis gas is fed to the reactor (1) through the conduit (6). Also, so that the concentration of catalyst components such as ruthenium, halogen and solvent in the reactor is kept constant, these are fed through the conduit (10).The typical reaction temperature in the reactor (1) is 180 °C. ~260°
C range, and typical reaction pressures are 300-600
kg/C value range.

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

The ethanol produced and the co-produced by-products are entrained by the synthesis gas flowing unreacted in the liquid medium and led through conduit (7) to the cooler (2). Here, the ethanol and by-products are cooled and transferred to a high-pressure gas-liquid separator (3
) into a liquid phase containing non-condensable gas and condensate. Industrially, this non-condensable gas is recycled back to the reactor.

The gas phase led into the conduit (8) is accompanied by a small amount of products such as methanol. On the other hand, the liquid phase is led to the conduit (9).

The gas phase led into the conduit (8) has a pressure of 11j! ff valve (4
) and into the conduit (9) is removed through the level control valve (5).

(Function) In the present invention, raw material synthesis gas is brought into contact with a liquid-phase homogeneous catalyst containing a ruthenium compound as a main catalyst, dissolved in the liquid phase using ethanol, and taken out of the reaction system together with the liquid phase. According to this method, there is no new accumulation of by-product carbon dioxide in the recycled gas, and a decarbonation device for the recycled gas system is not required, resulting in a significant improvement in economic efficiency. That is, the method of the present invention improves C1 chemistry technology to an industrial level compared to conventional methods.

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

Example 1 12 g (56 mg atoms as Ru) of triruthenium dodecacarbonyl (Put(Go)tz), 28.
8 g (168 mg atoms as Co) dicobalt octacarbonyl (Cot(Co)s), 47.6 g
Lithium chloride (LiCI) (11,201 wg atoms as CI) and 560 g of tributylphosphine oxide (BuzPO) as a solvent were placed in a back-type reactor with a capacity of 1.5°C, and after closing the reactor, monoxide was added from the bottom of the reactor. Synthesis gas having a molar ratio of carbon to hydrogen of about 1:2 was fed in small portions. The temperature of the reactor started to increase when the pressure of the reactor reached 360 kg/aa. The temperature of the reactor was 225°C.
When the reaction pressure is 450 kg, feed the synthesis gas and increase the reaction pressure to 450 kg.
/aa, only syngas at 1850 f 7
Supplied on time. At the same time, ruthenium in the reactor,
In order to keep the concentrations of the halogen and liquid solvent constant, they were dissolved in methyl acetate and fed from the bottom of the reactor. Methyl acetate was supplied in an amount of 160 g per hour.

The gas at the reactor outlet is cooled to 20°C and condensed, passing through the liquid level 141 regulating valve (5) of the low-pressure gas-liquid separator (3) to produce an average of 0.217 kg (= C) of liquid per hour. was collected and analyzed by gas chromatography.

The results are shown in Table 1.

Table 1 300 g of this product liquid was placed in a 500 ml autoclave, carbon dioxide was introduced under pressure, and the solubility of carbon dioxide was measured. The amount of dissolved carbon dioxide increases with pressure, and this tendency increases as the pressure increases.When the solubility measured under a carbon dioxide partial pressure of 20°Cl2O atmosphere is converted to 1 atmosphere, the solubility is 7.42 (1/kg/ atmospheric pressure) (=B).

On the other hand, the gas phase recovered from the pressure control valve (4) and the liquid phase recovered from the liquid level control valve (5) have a temperature of 0°C.
, 1 atm, a total of 27.21 (-A) of carbon dioxide was contained. From this result, A/B/C is 17
It turned out to be atmospheric pressure.

Next, put the same catalyst into the reactor and increase the reaction pressure to 4 atm so that the carbon dioxide partial pressure at the reactor outlet is 17 atm or higher.
Synthesis gas containing 3.2% carbon dioxide was fed at approximately 1910 ffi for 7 hours while maintaining the flow rate at 65 kg/cd. At the same time, ruthenium, halogen, and liquid solvent in the reactor were dissolved in methyl acetate and fed from the bottom of the reactor so that their concentrations were kept constant. Methyl acetate was supplied in an amount of 160 g per hour.

The gas at the outlet of the reactor is condensed and passed through the liquid level control valve (5) of the low pressure gas-liquid separator (3) to produce an average of 0.221 g/hour.
kg of liquid was collected and analyzed by gas chromatography. The results are shown in Table 2.

It can be seen that the amount of ethanol produced in Table 2 does not change much compared to when no carbon dioxide is supplied.

The gas compositions of the non-condensable gas phase and the liquid phase containing condensate at the outlet of the gas-liquid separator are shown in Table 3 together with the feed rates at the inlet of the reactor.

From Table 3, most of the supplied carbon dioxide is recovered from the non-condensable gas in the gas-liquid separator, and most of the carbon dioxide newly produced as a by-product in the reactor is dissolved in the condensate and taken out of the system. , it can be seen that there is no new accumulation of carbon dioxide into the gas phase.

Table 3 Unit: 2/hour (Effect) When using the method of the invention, there is no new accumulation in the recycle gas system. As a result, a decarboxylation device for recycled gas becomes unnecessary.

[Brief explanation of the drawing]

FIG. 1 shows an example of a manufacturing flow sheet for implementing the present invention. In FIG. 1, each reference numeral is as follows. 1 Reactor, 2 Cooler, 3 High pressure gas-liquid separator, 4 Pressure reducing valve, 5 Liquid level control valve

Claims (1)

[Claims] (1) Synthesis gas is brought into contact with a ruthenium compound and a halogen compound, or a liquid medium containing a ruthenium compound, a cobalt compound, and a halogen compound under high temperature and pressure to generate oxygen-containing compounds such as methanol and ethanol, which are then delivered to the outlet of the reactor. In the method of producing ethanol by cooling it to below the reaction temperature using an installed cooler and gas-liquid separator and separating it into a liquid phase containing non-condensable gas and condensed liquid, the amount of carbon dioxide produced as a by-product per hour is The production amount is A (l/hr
), the amount of carbon dioxide dissolved in 1 kg of liquid phase at the operating temperature of the gas-liquid separator is B (l/kg/atmosphere), and the amount of liquid phase taken out from the gas-liquid separator per hour is C (kg/hr). In this case, the carbon dioxide partial pressure at the reactor outlet is expressed by the formula A/B/
A method for producing ethanol, which comprises supplying carbon dioxide to a reactor so as to maintain the pressure above C (atmospheric pressure).