JPS6348236A - Production of ethanol - Google Patents

Abstract

PURPOSE:To obtain the aimed substance and to recycle a liquid containing Ru and an organic phosphorus compound, by feeding a synthesis gas to a liquid medium containing an Ru compound, etc., at a high temperature under high pressure, adding an oxide of a trivalent organic phosphorus compound to a condensate of a reaction product and distilling. CONSTITUTION:A synthesis gas is continuously fed to a liquid medium containing an Ru compound, preferably oxide, halide or complex as a catalyst and a halogen compound, e.g. metal salt or ammonium salt, as a cocatalyst at a high temperature of 180-260 deg.C under a high pressure of 300-500kg/cm<2> in a reactor and the reaction product, together with the unreacted synthesis gas, is cooled to recover a condensate containing the reaction product and part of the Ru compound. An oxide of a trivalent organic phosphorus compound, e.g. triphenylphosphine oxide, is added to the condensate and distillation is carried out to afford the aimed substance. A liquid containing the Ru and trivalent organic phosphorus compound is recycled to the reactor. Thereby recovery loss of expensive Ru can be minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for directly synthesizing ethanol from carbon oxide 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 a ruthenium compound as a catalyst and a halogen compound as a cocatalyst.

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

Synthesis gas containing -carbon oxide and hydrogen is continuously introduced into a catalyst-containing liquid medium containing a ruthenium compound and a halogen compound held in one reactor where the ``t'' and U are decomposed. The present inventors have already filed an application (Japanese Patent Application No. 60-57544) for a method of producing ethanol by supplying the gas to a gas, producing ethanol, and taking out the generated ethanol along with unreacted synthesis gas. , filing date: March 23, 1985).According to this method,
A reactor holds a catalyst-containing liquid medium in which ethanol is synthesized. According to this method, alcohols or esters are entrained in unreacted synthesis gas, and highly concentrated ethanol can be produced.

However, among the catalyst components, a part of the ruthenium compound evaporates out of the reaction system along with unreacted synthesis gas or gaseous reaction products, and the amount of ruthenium in the reaction ice decreases with time. As a result, as the amount of ruthenium in the reactor decreases, the production activity of child tanol decreases, resulting in a drawback that ethanol cannot be produced at a constant rate. Therefore, a technique is needed to recover the volatilized ruthenium and recycle it to the reactor.

As a result of studies conducted by the present inventors, it was found that ruthenium is a low-boiling substance, ruthenium pentacarbonyl form M (Ru(Co)).
volatilizes with s). But is this compound difficult? soluble triruthenium carbonyl (Ru 3 ((:O
') + g, ), adhering to the container or some precipitation not only makes the method of recycling ruthenium into the reactor extremely difficult, but also causes loss of expensive luteum and is economically unsatisfactory. Significantly reduces sexual performance.

A method for recovering volatilized ruthenium with methanol or ethanol in a homogeneous catalytic reaction using a ruthenium compound has already been disclosed (US 412.033).

According to this method, ruthenium compounds are recovered with a large amount of methanol or ethanol.

This means that the ruthenium compound (triruthenium dodecacarponyl) is soluble in methanol or ethanol! This is because a large amount of methanol or ethanol is required to homogenize the ruthenium compound.

However, when the ruthenium homogenized in this manner is recycled to the reactor, a large amount of solvent must be simultaneously supplied to the reaction system along with the ruthenium. and force ζ,
Supplying a large amount of solvent to the reactor not only significantly reduces the ruthenium concentration in the reaction system, but also changes the solvent system of the reaction system, which has an extremely negative effect on the reaction.

Thus, in order to stably produce ethanol, a technology is required to collect and homogenize the volatilized rutenyl filtrate, and to recycle it to the reactor without affecting the reaction.

The object of the present invention is to solve the above-mentioned problems associated with recovering volatilized ruthenium and recycling it into a reactor again, and to provide a method for continuously and stably producing ethanol from synthesis gas. It is to provide.

The inventors of the present invention have conducted intensive studies to solve these problems. As a result, using a ruthenium compound as a catalyst:
In a liquid-phase homogeneous catalytic reaction using a halogen compound as a cocatalyst, the reaction product is condensed, the volatilized ruthenium compound is recovered together with the reaction product, and trivalent organic phosphorus compound oxide is added to it and heated. They discovered that a mixture of ruthenium compounds and trivalent organic phosphorus compound oxides obtained by distilling off the product is easily soluble in a wide variety of solvents and can form a homogeneous liquid, thus completing the present invention. did.

That is, the present invention continuously supplies synthesis gas to a liquid medium containing a ruthenium compound and a halogen compound held in a reactor at a high temperature and under high pressure, thereby producing an oxygen-containing compound containing ethanol as a main component. In a method of producing ethanol by synthesizing a reaction product, and removing the reaction product from the reactor along with unreacted synthesis gas, i) ii) adding an oxide of a trivalent organic phosphorus compound to the condensate; iii) Then, the reaction product is distilled off from the condensate by fumigation, and i
v) A method for producing ethanol, characterized in that the thus obtained liquid containing ruthenium and a trivalent organic phosphorus compound is recycled to a reactor.

As the ruthenium compound used in the method of the present invention, any ruthenium compound that forms a complex having carbon monoxide coordination under the reaction conditions can be used. Examples of these include ruthenium metal, 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, and acetic acid. Examples include ruthenium and 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 carbonyl in which at least part of the carbon monoxide ligand is replaced with another ligand. Ruthenium complexes 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.

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

These halogen compounds include alkali metal salts having halogen ions such as chloride ions, bromide ions, and iodine ions as anions constituting the salts, metal salts such as alkaline earth metal salts, ammonium salts, 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. Eid etc.
(3) Examples of quaternary phosphonium salts include tetraphenylphosphonium chloride, tetra-n-butylphosphonium bromide, n-hebutyltriphenylphosphonium bromide, benzyltriphenylphosphonium iodide, methyltriphenylphosphonium chloride, etc. Examples of iminium 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. Iminium salts substituted with methyl or 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, hydrogen iodide, and (7) examples of acid halides.
Examples of the transition metal halide (8) 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.

In the method of the present invention, when phosphoric acid or a phosphoric acid ester such as methyl phosphate or ethyl phosphate is used in addition to a halide as a cocatalyst for ruthenium compounds and cobalt compounds, the ethanol production activity and selectivity are further improved. do. This phosphoric acid or phosphoric acid ester not only improves methanol synthesis activity from raw material synthesis gas but also has the effect of accelerating the homologation rate from methanol to ethanol. As a result, the ethanol production activity and selectivity are significantly improved.

The amount of phosphoric acid or phosphoric ester used in the method of the present invention is 0 phosphorus atom per 1 gram atom of ruthenium.
．． In the range of 1 to 20 gram atoms, more preferably 1 to 1
It is in the range of 0 gram atom.

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, chloropencune, 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, esters such as methyl acetate, ethyl butyrate, methyl benzoate, γ-butyrolactone, acetone,
Ketones such as acetophenone and hensifhenone, N-
Methylpyrrolidin-2-one, N-ethylpyrrolidine-
N-substituted amides such as 2-one, N,N-dimethylacetamide, N-methylpiperidone, hexamethylphosphoric triamide, N,N-diethylaniline, N-
Tertiary amines such as methylmorpholine, pyridine, and quinoline, sulfones such as sulfolane, sulfoxides such as dimethyl sulfoxide, 1,3-dimethyl-
Urea derivatives such as 2-imidazolidinone, further triethylphosphine oxide, tri-n-propylphosphine oxide, tri-n-butylphosphine oxide, tri-n-hebutylphosphine oxide, tri-n-octylphosphine oxide, triphenylphosphine oxide, Examples include oxides of trivalent organic phosphorus compounds such as tri-p-+-dylphosphine 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 phosphine oxides.

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.

The method of the present invention has a reaction temperature in the range of 160 to 300°C,
Preferably it is 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/cm",
Preferably, it is in the range of 300 to 500 Kg/cn+2. The higher the reaction pressure is, the more preferable it is for the reaction between carbon oxide and hydrogen, but for practical purposes, it is preferably 800 kg/cm'' or less.

The molar ratio of carbon monoxide and hydrogen used as raw materials is 1:l
The range of O to 10:1 is preferable. However, as extreme examples, it is possible to carry out the method of the present invention by selecting reaction conditions, such as using pure carbon oxide in the presence of water, using pure hydrogen in the presence of carbon dioxide, etc. It is.

Further, other components inert to the present invention, such as methane, nitrogen, etc., may be present in the raw material synthesis gas. In the method of the present invention, the oxide of the trivalent organic phosphorus compound used is a trialkylphosphine oxide whose alkyl group has a carbon number in the range of 2 to 20, and examples of such trialkylphosphine oxide include: Examples include triethylphosphine oxide, tri-n-propylphosphine oxide, tri-butylphosphine oxide, tri-〇-hebutylphosphine oxide, tri-n-octylphosphine oxide, and the like.

Further, in the method of the present invention, the oxide of the trivalent organic phosphorus compound used is a triarylphosphine oxide in which the aryl group is a phenyl group or a phenyl group in which a part of the phenyl group is substituted with an alkyl group or a halogen. , Examples of such doarylphosphine oxides include triphenylphosphine oxide,
Examples include tri-p-)lylphosphine oxide and tri-p-chlorophenylphosphine oxide.

Among these phosphine oxides, in a reaction using a trivalent organic phosphorus compound oxide as a reaction solvent, it is preferable to use the same trivalent organic phosphorus compound oxide as used in the reaction.

The amount of the oxide of the trivalent organic phosphorus compound used in the method of the present invention is 1 gram atom or more per ruthenium Durham atom of the amount of ruthenium to be volatilized. It becomes uniform. However, if the amount of trivalent organic phosphorus compound used is too large, the ruthenium concentration in the reactor will decrease. Therefore, the preferred amount used is in the range of 3 to 20 gram atoms of phosphorus per atom of ruthenium volatilized.

The temperature at which the oxide of a trivalent organic phosphorus compound is added to the ruthenium-containing reaction product recovered in the method of the present invention and heated is preferably in the range of 70°C or higher and 300°C or lower. When this heating temperature is 70° C. or lower, a reaction time of 10 hours or more is required to homogenize the ruthenium. On the other hand, if the heating temperature is 300° C. or higher, ruthenium becomes metal, and the ruthenium compound cannot be made uniform. Therefore, the preferred heating temperature is 120°C to 200°C.
℃ range.

In the method of the present invention, as a method of adding a trivalent organic phosphorus compound oxide to the recovered condensate and heating it, the recovered condensate containing Ruthenium and the trivalent organic phosphorus compound oxide are heated to a predetermined temperature. It can be carried out in a continuous manner by heating and passing through a reaction zone. Also,
It can also be carried out by a batch method in which the collected ruthenium-containing condensate is placed in an autoclave and heated.

In the method of the present invention, the reaction product is removed by distillation from the condensate heated as described above, and the liquid containing ruthenium and trivalent organic phosphorus compound oxide thus obtained is the reaction product or the above-mentioned liquid. It is a reaction solvent. Among the reaction products, those that can be converted into ethanol or raw material synthesis gas in the reactor are preferred. Such examples include methanol, methyl formate, propyl formate, methyl acetate, acetate, propyl acetate, methyl ethyl ether, diethyl ether.

However, the method of the present invention is not limited to liquids other than reaction products or reaction solvents as long as they can dissolve the thus obtained ruthenium and trivalent organic phosphorus compound oxide.

Furthermore, the oxide of ruthenium and trivalent organic phosphorus compound thus obtained is a homogeneous liquid above the melting point of the oxide used. That is, for example, when tri-n-propylphosphine oxide is used as the oxide of the trivalent organic phosphorus compound, the temperature is 36°C or higher, and when tri-n-butylphosphine oxide is used, the temperature is 6°C.
It becomes a homogeneous liquid at a temperature of 7°C or higher, or 54°C or higher when tri-n-octylphosphine oxide is used. Therefore, the method of the present invention can be carried out even if the oxides of ruthenium and trivalent organic phosphorus compounds thus obtained are recycled to the reactor at a temperature higher than the melting point of the oxides used, without melting them into the above-mentioned liquids. can do.

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

In FIG. 1, a reactor (1) holds a liquid medium containing a ruthenium compound and a halogen compound. Synthesis gas is fed to the reactor (1) through conduit (2). Typical reaction temperature in reactor (1) is 180~
260°C and typical reaction pressure is 300-5'0
0 Kg/am”.
Synthesis gas continuously fed into ) contacts a catalyst in a liquid medium to produce ethanol.

The produced ethanol, the by-products produced at the same time, and the easily volatilized ruthenium complex (Ru
(Co) 5) is entrained by the synthesis gas flowing unreacted in the liquid medium and led through the conduit (3) to the cooler (4). Here, the ethanol, by-products and volatile ruthenium are cooled and separated into non-condensable gas and condensate in a high-pressure gas-liquid separator (5). The liquid level of this high-pressure gas-liquid separator (5) is kept constant by a liquid level control valve (10).

The gas phase introduced into the conduit (6) is reduced in pressure to usually 10 to 30 Kg/cm'' through a pressure reducing valve (8).The gas phase is further introduced to a low pressure gas-liquid separator (11) through a cooler (9).

On the other hand, the liquid phase led to the conduit (7) is transferred to the liquid level control valve (10).
and is led to a low-pressure gas-liquid separator (11). This low-pressure gas-liquid separator (11) separates the gas into non-condensable gas and condensate again. The liquid level of this low-pressure gas-liquid separator (1) is maintained at a constant degree by a liquid level control valve (15).

The gas phase passes through the conduit (12) and is reduced to atmospheric pressure by the pressure reducing valve (13). This gas phase is accompanied by unreacted synthesis gas, small amounts of carbon dioxide and products such as methane and small amounts of methanol.

On the other hand, in addition to the condensed products, most of the volatilized ruthenium is condensed and entrained in the liquid phase, and is recovered together with the products. The liquid phase led to the conduit (14) is passed through the liquid level control valve (1
5) and is led to the conduit (19), and this conduit (19)
It is mixed with the oxide of the trivalent organic phosphorus compound introduced from the oxide tank (16) of the trivalent organic phosphorus compound into the conduit (1 day) by the pump (17). This mixture is heated to usually 120 to 200°C in a heater (20), and then cooled to below room temperature in a cooler (21). This mixture consists of volatilized ruthenium, products and oxides of trivalent organophosphorus compounds. This mixture is separated into a product and an oxide of a trivalent organic phosphorus compound containing ruthenium in a thin film evaporator (22), and the product is passed through a conduit (22).
3).

On the other hand, the oxide of the trivalent organic phosphorus compound containing ruthenium is introduced into the conduit (24), pressurized to the reaction pressure by the pump (25), and recycled to the reactor through the conduit (26).

In the method of the present invention, oxide of a trivalent organic phosphorus compound is added to a product solution containing volatilized ruthenium, heated, the product is removed, and the resulting ruthenium complex is used as a homogeneous solution in a reactor. It is recycled.

According to this method, the process of recovering the volatilized ruthenium compound and recycling it to the reactor can be treated as a homogeneous liquid throughout the process. As a result, the complex process that would be possible if the solid was recycled back to the reactor is avoided, compared to the case where the ruthenium compound precipitates out and has to be handled as a solid. Furthermore, it has the economical advantage that the loss of ruthenium in the process of recovering and recycling ruthenium is extremely small.

That is, the method of the present invention improves C1 chemistry technology to an industrial level compared to conventional methods.

Shuang Shige The method of the present invention will now be described in more detail with reference to Examples.

Example 1 Triruthenium dodecacarbonyl, 561 g atoms (12 g) as ruthenium atoms, 280 mmo+ (173
g) of bis(triphenylphosphine)iminium bromide, 168 o1 (16°5 g) of phosphoric acid and 560 g of tri-n-butylphosphine oxide as liquid solvent in a tubular reactor (diameter 4 cm % length 120
cm) After entering from the bottom and closing the reactor, 4-warming was started when the pressure of the reactor reached 360 h/cm2.

When the temperature of the reactor reached 210'C, synthesis gas was continuously supplied from the bottom of the reactor, and the synthesis gas was heated to 200012/
The reaction was carried out while maintaining the reaction pressure at 450 kg/cm2. Meanwhile, tri-n-butylphosphine oxide was supplied to the conduit (19) at a rate of 11 g per hour by the pump (17), mixed with the condensate, and heated by contact with the condensate at 160° C. for 1 minute using the heater (20). After that, the cooler (21
) and cooled to 5°C. The product was separated from trivalent organic phosphorus compounds containing ruthenium using a thin film generator, and 172 g of product and 13.5 g of ruthenium-containing tri-n-butylphosphine oxide were recovered per hour. . This ruthenium-containing tri-n-butylphosphine oxide was heated to 70 DEG C. to form a homogeneous liquid, which was then pressurized to 450 kg/cm@2 using a 2-tube (25) and recycled to the reactor.

On the other hand, the product distilled from the thin film evaporator was analyzed by gas chromatography, and the following results were obtained.

Methanol 38.7g Ethanol 75.8g Propertool 12.5g Methyl formate 8.6g Ethyl formate 10.5g Methyl acetate 7.9g Acetaldehyde 9.2g Others 8.8g In the comparative examples, low pressure gas-liquid separator (11) outlet conduit (
14) was sampled. As a result of analyzing this sample liquid by infrared absorption method, the presence of ruthenium in the form of Ru(Co)s and Ru3(Co)'+□ was confirmed. This sampling liquid was heated at 80°C for 200 m
mHgT: When concentrated, Ru (Co
) s was distilled out and ruthenium could not be separated. Furthermore, the concentrate contains ruthenium containing Ru 3 (Co
) + 2 solid, and it was not possible to dump the ruthenium into the reactor.

The ruthenium that evaporates is condensed and recovered together with the products, but if left as is, it will precipitate as a poorly soluble ruthenium complex.

However, as shown in the example, if the oxide of a trivalent organic phosphorus compound is added to the condensate containing ruthenium, heated, and the product is distilled off, the oxide of a trivalent organic phosphorus compound containing ruthenium can be removed. A homogeneous liquid is obtained, and the ruthenium can be recycled to the reactor as a homogeneous liquid.

As described above, by using the method of the present invention, the process of recovering ruthenium and recycling it to a reactor can be treated as a homogenized liquid, and the recovery loss of expensive ruthenium can be extremely reduced.

[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 code is 1,
Reactor, 4.9.21, Cooler, 5, High pressure gas-liquid separator, 8.13, Pressure reducing valve, 10.15, Liquid level control valve, 11, Low pressure gas-liquid separator, 16, Organic phosphorus compound Oxide, 17.2
5. Pump; 20. Heater; 22. Thin film evaporator.

Claims (1)

[Claims] (1) Synthesis gas is continuously supplied to a liquid medium containing a ruthenium compound and a halogen compound held in a reactor under high temperature and high pressure to produce a reaction product consisting of an oxygen-containing compound whose main component is ethanol. In a method of producing ethanol by combining the reaction product with unreacted synthesis gas and removing it from the reactor, i) the unreacted synthesis gas containing the reaction product removed from the reactor is ii) adding an oxide of a trivalent organic phosphorus compound to the condensate and heating it; iii) then condensing. A method for producing ethanol, comprising: removing a reaction product from the liquid by distillation, and iv) recycling the thus obtained liquid containing ruthenium and a trivalent organic phosphorus compound to a reactor.