JPS63145243A - 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 methane is supplied to a reactor in a manner to keep partial pressure of methane 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 cooled below the reaction temperature with a cooler and a gas-liquid separator to separate noncondensed gas from a liquid phase containing condensed liquid. In the above ethanol-production process, methane is supplied to the reactor in a manner to keep the partial methane pressure to >=A/B/C atm at the outlet of the reactor, wherein A (l/hr) is volume of by-produced methane, B (l/kg/atm) is amount of soluble methane 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 loss of unreacted synthesis gas can be decreased.

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.

(Prior Art and Problems to be Solved by 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), and a method for selectively producing methanol and ethanol by contacting synthesis gas with a homogeneous ruthenium catalyst, a halogen or a halogenation promoter, and an organic oxidized phosphine compound (Japanese Patent Laid-Open No. 57-8232).
No. 7).

In these methods, the one-pass addition rate of synthesis gas in the reactor is more than ten percent, and therefore unreacted synthesis gas is recycled to the reactor and used repeatedly. Since by-product methane and carbon dioxide accumulate in this unreacted synthesis gas recycling system, a portion of the unreacted synthesis gas recycling system is constantly purged and new synthesis gas is replenished to match the purge amount. It is necessary to keep the synthesis gas concentration constant. However, the loss of synthesis gas associated with this purge directly leads to a decrease in the utilization rate of synthesis gas, and therefore has a large impact on the economic efficiency of the process.

Thus, in order to industrially produce ethanol, a technology is required to further reduce the loss of unreacted synthesis gas that accompanies methane purging.

An object of the present invention is to provide a method for economically producing ethanol by solving the economic problems associated with separating accumulated methane and unreacted synthesis gas, and minimizing loss of unreacted synthesis gas. It is something to do.

(Means for Solving the Problems) The present inventors have conducted intensive studies on economical methane purging methods. 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 methane and synthesis gas in the liquid phase in a gas-liquid separator. Furthermore, by applying this, methane is supplied to the reactor, the methane partial pressure at the reactor outlet is increased, and the entire amount of methane produced as a by-product in the reactor is dissolved in the liquid phase in the gas-liquid separator and removed from the reaction system. This method eliminates additional accumulation of unreacted synthesis gas in the recycling system. As a result, there is no need to purge recycled gas,
The present invention was completed based on the discovery that the loss of synthesis gas can be significantly reduced.

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 non-condensable gas and condensed liquid, the amount of by-produced methane per hour is The amount of methane produced is A (1,/hr), and the amount of methane dissolved in 1 kg of liquid phase at the operating temperature of the gas-liquid separator is B (l/kg/atm).
, the amount of liquid phase taken out from the gas-liquid separator per hour is C(
This method of producing ethanol is characterized in that methane is supplied to the reactor so that the partial pressure of methane at the outlet of the reactor is maintained equal to or higher than the formula A/B/C (atmospheric pressure).

Any ruthenium compound that can be used in the method of the present invention can be used as long as it forms a complex having carbon monoxide coordination 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. ,
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, ruthenium with acids 16M yellow, 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 the ruthenium compound used in the method of the invention in the liquid medium ranges from 0.1 to 300 parts by weight, expressed as ruthenium metal, per 1000 parts by weight of the liquid medium.

In addition to metal cobalt, cobalt compounds include cobalt mineral salts such as cobalt oxide, cobalt hydroxide, cobalt chloride, cobalt iodide, and cobalt nitrate.
These include organic acid salts of cobalt such as cobalt acetate, cobalt benzoate, and cobalt naphthenate. In addition, coordination compounds can also be used, such as cobalt carbonyl, such as dicobalt octacarbonyl, tetracobalt dodeca, 'J luponyl, cyclobencungenyl cobalt dicarbonyl, Examples include cobalt complexes in which cobalt is coordinated with ligands containing oxygen, sulfur, halogen, nitrogen, phosphorus, arsenic, antimony, bismuth, etc., and their salts. Among these cobalt compounds are cobalt oxides, cobalt halides, cobalt carbonyls, cobalt organic acid salts, cobalt acetylacetonates, or cobalt carbonyls.

Also preferred are cobalt complexes in which some of the carbon monoxide ligands are replaced with other ligands.

The amount of cobalt compound used in the method of the invention in the liquid medium ranges from 0.100 gram atoms of cobalt per gram atom of ruthenium, preferably from O to 10 gram atoms.

Further, 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, as an example of ('1) metal salt,
(2) Examples of ammonium salts include trimethylammonium chloride, trimethylammonium bromide, trimethylammonium iodide, etc. Dydo, 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 Examples of salts include bis(triphenylphosphine)iminium chloride, bis(triphenylphosphine)iminium bromide, bis(triphenylphosphine)iminium iodide, and at least a portion of the phenyl group of these iminium compounds is methyl. iminium salts substituted with groups, 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.
) Examples of hydrogen halides include hydrogen chloride, hydrogen bromide, and hydrogen iodide; (7) Examples of acid halides include acetyl chloride and acetyl bromide; and (8) transition metal halides. Examples include benzyl 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. Use "" Saturated and aromatic hydrocarbons such as decalin, tetralin, kerosene, benzene, toluene, xylene, durene, hexamethylbenzene, halokenes such as chloropentane, 0-dichlorobenzene, p-chlorotoluene, fluorobenzene Hydrocarbons, dioxane, tetrahydrofuran, ethyl ether, anisole, phenyl ether, diglyme, tetraglyme, ethers such as 18-crown-6, esters such as methyl acetate, ethyl butyrate, methyl benzoate, T-butyrolactone, acetone , ketones such as acetophenone and benzophenone, N
-N-substituted amides such as methylpyrrolidin-2-one, N-ethylpyrrolidin-2-one, N,N-dimethylacetamide, N-methylpiperidone, hexamethylphosphoric triamide, N,N-diethylaniline, N - 3 such as methylmorpholine, pyridine, quinoline, etc.
amines, sulfones such as sulfolane, sulfoxides such as dimethyl sulfoxide, urea derivatives such as 1,3-dimethyl-2-imidazolidinone, and
triethylphosphine oxide, tri-lowpropylphosphine oxide, tri-n-butylphosphine oxide, tri-n-butylphosphine oxide,
Examples include oxides of trivalent organic phosphorus compounds such as tri-octylphosphine oxide, triphenylphosphine oxide, tri-P-)lylphosphine oxide, tri-p-chlorophenylphosphine oxide, and 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.

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

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. When the reaction temperature is less than 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.

In addition, the reaction pressure is in the range of 150 to 800 kg/d, preferably in the range of 300 to 600 kg/c+fl.The higher the reaction pressure is, the more preferable it is for the reaction of carbon oxide and hydrogen, but the practical pressure As for 800 kg/ct
A or less is preferable.

The molar ratio of carbon monoxide and hydrogen used as raw materials is 1:
A range of lO to 10:1 is preferred, but as an extreme example, the reaction conditions may be selected to use pure carbon oxide in the presence of water or even pure hydrogen in the presence of carbon dioxide. It is possible to carry out the method of the invention by: Further, other components inert to the present invention, such as nitrogen and carbon dioxide, may be present in the raw material synthesis gas.

In the method of the present invention, the method of cooling the reactor 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 non-condensable gas and condensed liquid is known to those skilled in the art. method. At this time, when the cooling temperature is lower, the amount of methane dissolved in the condensate increases, while the amount of water) and carbon oxide dissolved in the liquid phase decreases. Therefore, the lower the cooling temperature is, the more preferable it is, but the cooling cost and production i1A per hour (1/hr) are the same when the reaction is carried out using the catalyst used in the method of the present invention and without supplying methane to the reactor. The amount of methane produced when
This is the amount converted to atmospheric pressure.

In the method of the present invention, the amount B (1/kg/atm) of methane dissolved in 1 kg of the liquid phase at the operating temperature of the gas-liquid separator is the amount B (1/kg/atmosphere) of methane obtained in the reaction using the catalyst used in the method of the present invention. The solubility of methane in the liquid phase of the gas-liquid separator is measured at the operating temperature of the gas-liquid separator, and is a value converted to 0°C11 atmosphere. 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, methane is injected under pressure, and after stirring for a predetermined period of time, a part of the liquid phase is extracted and its weight and the amount of gas generated from it are measured. .

In the method of the present invention, the liquid phase itc (kg/hr) taken out from the gas-liquid separator per hour refers to the amount of liquid phase itc (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 without supplying methane to the reactor. per hour of the liquid phase containing the condensate separated in a gas-liquid separator, f In Figure 1, reactor (1) is charged with ruthenium compounds and halogen compounds or with ruthenium compounds, cobalt compounds and halogen compounds. The liquid solvent contained therein is retained. 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 conduits (10). Typical reaction temperature of reactor (1) is 180-260
'C range, typical reaction pressure is 300-600
The range is kg/C.

Synthesis gas continuously fed into such a reactor 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 led through conduit (7) to the cooler (2), where the ethanol and by-products are is cooled and passed through a high-pressure gas-liquid separator (
In step 3), it is separated 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 L! The liquid introduced through the one-section valve (4) and into the conduit (9) is removed through the skin control valve (5).

(Function) In the present invention, when producing ethanol by bringing the raw material synthesis gas into contact with a liquid-phase homogeneous catalyst having a ruthenium compound as the main catalyst, methane is supplied to the reactor so that the methane partial pressure becomes a predetermined pressure or higher. According to this method, by-produced methane is dissolved in the liquid phase in a gas-liquid separator and taken out of the reaction system together with the liquid phase, there is no new accumulation of by-produced methane, and unreacted synthesis gas is recycled. The methane concentration in the reactor is maintained within a certain range that is acceptable for the process, making it unnecessary to purge unreacted synthesis gas in the recycling system. As a result, the loss of synthesis gas is reduced and the utilization rate for ethanol is improved. 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 12g (56n+g atoms as Ru) of triruthenium dodecacarbonyl (RII3(Co)l!), 2
8.8 g (168 a g atoms as Co) of dicobalt octacarbonyl (Cot(Co)s), 47.6
g (1120 mg atoms as CI) of lithium chloride (LiCl) and 560 g of tributylphosphine oxide (BusPO) as solvent in a volume of 11.5
ffi was placed in the front-type reactor, and after closing the reactor, synthesis gas with a molar ratio of carbon monoxide and hydrogen of about 1:2 was supplied little by little from the bottom of the reactor.The pressure in the reactor was 360 kg/
The temperature of the 6 reactors that started heating up when d reached 225
When the temperature reached °C, the synthesis gas was supplied and the reaction pressure was increased to 450 °C.
kg/aa, only the syngas was heated to 1850 f.
fi 7 hours. At the same time, in order to keep the concentrations of ruthenium, halogen, and the solvent in the reactor constant, these 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, and passes through the liquid level control 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 put into a 500 ml autoclave, methane was introduced under pressure, and the solubility of methane was measured.

The amount of methane dissolved is proportional to the pressure, and the solubility converted to 1 atm was 0.65 (j!/kg/atm) (=B).

On the other hand, as a result of gas chromatography analysis of the gas phase from the pressure ill 2ff valve (4), it was found that this gas phase contains O2.
'C, converted to 1 atmosphere 6. It contained methane of I N (=A). From this result, it was found that A/B/C was 43 atm.

Next, put the same catalyst into the reactor and increase the reaction pressure to 490 atm so that the methane partial pressure at the reactor outlet is 43 atm or higher.
Synthesis gas containing 8.1% methane was fed at approximately 2000 f/h while maintaining the methane at kg/cJ. At the same time, ruthenium, halogen, and liquid solvent in the reactor were dissolved in methyl acetate so that the four components were kept constant.
It was supplied 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 condensed and passed through the liquid level control valve (5) of the low-pressure gas-liquid separator (3) to produce an average of 0.214 ml per 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 methane is not 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, an amount of methane approximately equal to the amount supplied is recovered from the non-condensable gas in the gas-liquid separator, and most of the methane newly produced as a by-product in the reactor is dissolved in the liquid phase and released from the system. I know it will be taken out.

With the purging of 6.02 kg of methane in the liquid phase, 7.02 kg of -carbon oxide and 5.72 kg of hydrogen are lost.

On the other hand, when purging methane without dissolving it in the liquid phase, -carbon oxide 556
．． 81 and hydrogen 1118ffi must be purged, i.e. new by-product methane 6, Of! .

To avoid the accumulation of carbon monoxide 19.91 and hydrogen 40
．． 0 ffi needs to be purged.

Table 3 Unit = 2/hour (effect) If the method of the present invention is used, along with the purging of methane, -
7.01 carbon oxides and 5.72 hydrogen oxides are lost. On the other hand, when the newly produced by-products methane 6 and OIl are purged in the recycling system, carbon monoxide 19.91 and hydrogen 40.0
ffi is lost. In this way, by supplying methane such that the methane partial pressure is equal to or higher than a predetermined pressure, and dissolving the methane in the liquid phase and taking it out, the loss of synthesis gas is reduced compared to when the method of the present invention is not used. , -65 in carbon oxide
%, which is an 86% decrease in hydrogen.

[Brief explanation of the drawing]

FIG. 1 shows an example of a manufacturing flow sheet for carrying out 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. Production of methane as a by-product per hour in a 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 is A (l/hr)
, the amount of methane 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 methane partial pressure at the reactor outlet is expressed by the formula A/B/C (atmospheric pressure).
A method for producing ethanol, characterized by supplying methane to a reactor so as to maintain the above level.