JPS6257169B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION The present invention relates to a process for producing ethylene glycol from synthesis gas, ie a mixture of carbon monoxide and hydrogen. Ethylene glycol is an extremely important chemical product industrially as a raw material for polyester fibers, a raw material for organic chemicals, or a non-volatile antifreeze solution. [Prior Art] Conventionally, ethylene glycol has been produced by an oxidation reaction of ethylene. In recent years, as a method for producing ethylene glycol, a technology has been developed that uses synthesis gas, which is a cheaper and more abundant raw material than ethylene, as a raw material. For example, Special Publication No. 53-31122, Special Publication No. 55-43821
No., Special Publication No. 53-15047, Special Publication No. 50-32118, Special Publication No. 56-40131, Special Publication No. 55-5497, Special Publication No. 55
−33694, Special Publication No. 55-33697, Japanese Patent Publication No. 1973-
No. 125203, Special Publication No. 10894, Special Publication No. 1983-40698
No., JP-A-52-42809, JP-A-52-42810, JP-A-56-40132, JP-A-53-121714, JP-A-Sho.
No. 54-71098, JP-A-54-48703, JP-A-54-
No. 92903, JP-A-54-16415, JP-A-54-122211
No., JP-A-55-9065, JP-A-53-108889, JP-A-56-75498, JP-A-57-128654, JP-A-Sho
57-130941 and Japanese Patent Application Laid-open No. 57-130942, and U.S. Patent No. 4013700, 4199520, 4133776
No. 4151192, 4153623, 4225530, 4199521
As described in the specifications of No., No. 4190598, No. 4211719, and No. 4302547, a method of reacting carbon monoxide and hydrogen using a rhodium catalyst under high temperature and high pressure conditions is well known. It is being [Problems to be solved by the invention] However, the methods of the prior art exemplified above have not yet achieved sufficient catalytic activity to justify the use of expensive rhodium, and therefore cannot be implemented on an industrial scale. As a method, it had problems such as being difficult to adopt. [Means for Solving the Problems] The present inventors have arrived at the present invention as a result of taking the above facts into consideration and making intensive studies to increase the activity of rhodium catalysts. That is, the present invention provides a method for producing ethylene glycol by reacting carbon monoxide and hydrogen in a liquid phase in the presence of a rhodium catalyst, in which trialkylphosphine and amine-N-oxide or phosphine oxide are added to the reaction system. The gist of the present invention is a method for producing ethylene glycol, which is characterized by the presence of ethylene glycol. Hereinafter, the present invention will be explained in detail. The source of the raw material gases used in the present invention, ie, carbon monoxide and hydrogen, is not particularly limited, and may contain a small amount of inert gas such as nitrogen gas or carbon dioxide. The volume ratio of hydrogen to carbon monoxide is usually in the range of 1/10 to 10/1, and it is preferable to use a composition in the range of 1/5 to 5/1. In the present invention, rhodium is present as a catalyst component. As for the supply form of the rhodium component, any rhodium metal or rhodium compound capable of forming a rhodium carbonyl compound in the reaction zone can be used. Specific examples of the rhodium compound include zero-valent compounds such as dirhodium octacarbonyl; rhodium acetylacetonatodicarbonyl;
Monovalent complex compounds such as bromotris (pyridine) rhodium; salts such as rhodium trichloride, rhodium nitrate, rhodium acetate; oxides such as rhodium trihydroxide; trivalent complex compounds such as tris (acetylacetonato) rhodium; tetrarhodium Examples include clusters such as dodecacarbonyl and hexalodium hexadecacarbonyl; anion complexes such as rhodium tetracarbonyl anion and carbidehexarhodium pentadecacarbonyl anion. Further, as the rhodium component, it is also possible to use a rhodium compound to which trialkylphosphine, which will be described later, is coordinated in advance to be used as a reaction accelerator. Specific examples include RhH[P(i-Pr) ₃ ] ₃ ,
RhH( _PEt3 ) ₄ , RhH( _PEt3 ) ₃ , [trans−Rh
(CO) (Py) {P(i-Pr) ₃ } ₂ ] BPh ₄ , trans-
RhH(CO) [P(c- _{C6H11 ) 3} ] ₂ , trans-RhH
(CO) [P(i-Pr) ₃ ] ₂ , Rh(CO)[P(n-
Bu) ₃ ] ₂ , RhH[P(t-Bu) ₃ ] ₂ , RhH[P(c-
C ₆ H ₁₁ ) ₃ 〕 ₂ , [Rh(CO) ₃ P(i-Pr) ₃ 〕 ₂ , Rh ₂
(CO) ₃ [P(i-Pr) ₃ ] ₃ , Rh ₂ (CO) ₄ [P(t-
Bu) ₃ ] ₂ , Rh ₂ (CO) ₄ [P(c-C ₆ H ₁₁ ) ₃ ] ₂ , and the like. (However, i-Pr is an isopropyl group,
Et is ethyl group, Py is pyridine, Ph is phenyl group, c-C ₆ H ₁₁ is cyclohexyl group, n-
Bu represents an n-butyl group, and t-Bu represents a t-butyl group. ) The amount of rhodium used is expressed as the concentration in the reaction solution.
It is usually in the range of 0.0001 to 100 gram atoms, preferably 0.001 to 10 gram atoms per reaction solution. In the present invention, trialkylphosphine and amine-N-oxide or phosphine oxide, which act as a reaction accelerator, are further present as catalyst components. Trialkylphosphine is thought to have the function of coordinating with rhodium, the main catalyst, and controlling its electronic state. Although the details of the control mechanism are not necessarily clear, it is assumed that, for example, the electron donating ability of trialkylphosphine plays an important role. In fact, the hydrogenation activity and selectivity to ethylene glycol of rhodium-phosphine catalyst systems vary widely depending on the type of phosphine. Therefore, in order to achieve a high level of ethylene glycol yield, it is necessary to use the general formula of phosphine.
PR ₁ R ₂ R ₃ (wherein R ₁ , R ₂ and R ₃ represent a primary alkyl group, a secondary alkyl group, a tertiary alkyl group or a cycloalkyl group, even if they are different from each other) It is particularly effective to use trialkylphosphines of the formula Specific examples of trialkylphosphines used in the present invention include trimethylphosphine, triethylphosphine, tri-n-propylphosphine, tri-n-butylphosphine, tri-n-octylphosphine, tri- iso-butylphosphine, tris(2-ethylhexyl)phosphine,
3 such as di-n-butyl-iso-butylphosphine
trialkylphosphine with primary alkyl groups; tri-iso-propylphosphine, tri-sec-butylphosphine, tri-tert-butylphosphine, tricyclopentylphosphine, tricyclohexylphosphine, di- iso-propyl-cyclopentylphosphine, di-iso-propyl-t-butylphosphine, di-t-butyl-
iso-propylphosphine, di-t-butyl-sec
-butylphosphine, di-sec-butyl-iso-propylphosphine, di-iso-propyl-cyclohexylphosphine, di-t-butyl-cyclopentylphosphine, di-t-butyl-cyclohexylphosphine, di-sec -butyl-cyclohexylphosphine, dicyclopentyl-iso-propylphosphine, dicyclopentyl-t-butylphosphine, dicyclohexyl-iso-propylphosphine, diadamantyl-iso-propylphosphine, cyclopentyl-cyclohexyl-t
- Three secondary alkyl groups, tertiary alkyl groups, or cycloalkyl groups such as butylphosphine (hereinafter these are collectively referred to as "α-branched alkyl groups")
trialkylphosphine with; di-n-butyl-iso-propylphosphine, di-n-butyl-t-butylphosphine, di-n-butyl-cyclopentylphosphine, diethyl-iso-propylphosphine, diethyl - trialkylphosphine having two primary alkyl groups and one α-branched alkyl group, such as cyclopentylphosphine;
Di-iso-propyl-ethylphosphine, di-iso
-propyl-n-butylphosphine, di-t-butyl-methylphosphine, di-t-butyl-n-
Propylphosphine, di-t-butyl-n-butylphosphine, dicyclopentyl-ethylphosphine, dicyclopentyl-n-propylphosphine, dicyclopentyl-n-butylphosphine,
Dicyclohexyl-n-butylphosphine, dicyclohexyl-n-propylphosphine, diadamantyl-ethylphosphine, diadamantyl-
n-butylphosphine, dinorbornyl-ethylphosphine, dinorbonyl-n-butylphosphine, iso-propyl-t-butyl-n-butylphosphine, t-butyl-cyclohexyl-ethylphosphine, iso-propyl-cyclopentyl-
Examples include trialkylphosphines having one primary alkyl group and two α-branched alkyl groups, such as n-octylphosphine. The amount of the trialkylphosphine used is in the range of 0.2 to 1000 mol, preferably 0.5 to 100 mol, more preferably 0.8 to 10 mol, per gram atom of rhodium. Furthermore, the activity of the rhodium catalyst is significantly improved by adding amine-N-oxide or phosphine oxide together with the trialkylphosphine. Specific examples of the amine-N-oxide include trimethylamine-N-oxide, triethylamine-N-oxide, tri-n-propylamine-
N-oxide, aliphatic amine-N-oxides such as tri-n-octylamine oxide; tricyclohexylamine oxide, dicyclohexyl-
Alicyclic amine-N-oxides such as methylamine oxide; pyridine-N-oxide, 2-picoline-N-oxide, 3-picoline-N-oxide, 4-picoline-N-oxide, 4-methoxypyridine- N-oxide, 2,4,6-trimethylpyridine-N-oxide, nicotinamide-1
-oxide, quinoline oxide, isoquinoline oxide, 4-methylquinoline oxide 1,1'-dipyridyl monooxide, 1,1'-dipyridyl dioxide, 2,2'-dipyridyl monooxide, 2,
Such as 2'-dipyridyl dioxide, 1,8-phenanthroline monoxide, 1,8-phenanthroline dioxide, 4,5-phenanthroline monoxide, 4,5-phenanthroline dioxide, etc. Examples include cyclic amine-N-oxides. Further, specific examples of the phosphine oxide include three primary alkyl groups such as trimethylphosphine oxide, triethylphosphine oxide, tri-n-propylphosphine oxide, and tri-n-octylphosphine oxide. tri-iso-propylphosphine oxide, tri-sec-butylphosphine oxide, tri-t-butylphosphine oxide, tricyclopentylphosphine oxide, tricyclohexylphosphine oxide, etc. Trialkylphosphine oxides having α-branched alkyl groups; di-n-butyl-iso
-Propylphosphine oxide, di-n-butyl-t-butylphosphine oxide, diethyl-
Trialkylphosphine oxides having two primary alkyl groups and one α-branched alkyl group, such as iso-propylphosphine oxide; one primary alkyl group, such as dicyclopentyl-n-butylphosphine oxide; trialkylphosphine oxides having a class alkyl group and two α-branched alkyl groups; triarylphosphine oxides such as triphenylphosphine oxide; tris(dimethylamino)phosphine oxide, tris(n-butylamino) ) phosphine oxide, tris(n-hexylamino)phosphine oxide, tripyrrolidinophosphine oxide, tripiperidinophosphine oxide, and other aminophosphine oxides. If amine-N-oxide is used, the amount used is usually 1 gram atom of rhodium.
The amount ranges from 0.001 to 1000 mol, preferably from 0.1 to 500 mol, and more preferably from 1 to 100 mol. When phosphine oxide is used, the amount used is generally 0.001 to 1000 mol, preferably 0.1 to 500 mol, and more preferably 1 to 100 mol per gram atom of rhodium. Although the present invention can be carried out in the absence of a solvent, ie, the reaction raw materials and catalyst components themselves serve as reaction catalysts, a solvent can also be used. Examples of such solvents include ethers such as diethyl ether, anisole, tetrahydrofuran, ethylene glycol dimethyl ether, and dioxane; ketones such as acetone, methyl ethyl ketone, and acetophenone; methanol, ethanol, n
-Alcohols such as butanol, benzyl alcohol, phenol, ethylene glycol, diethylene glycol; formic acid, acetic acid, propionic acid,
Carboxylic acids such as toluic acid; esters such as methyl acetate, n-butyl acetate, benzyl benzoate;
Aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and tetralin; Aliphatic hydrocarbons such as n-hexane, n-octane, and cyclohexane; Halogenated hydrocarbons such as dichloromethane, trichloroethane, and chlorobenzene; Nitro compounds such as nitromethane and nitrobenzene; triethylamine,
Tertiary amines such as tri-n-butylamine, benzyldimethylamine, pyridine, α-picoline, 2-hydroxypyridine; N,N-dimethylformamide, N,N-dimethylacetamide, N-
Carboxylic acid amides such as methylpyrrolidone; inorganic acid amides such as hexamethylphosphoric acid triamide, N,N,N',N'-tetraethylsulfamide; N,
N'-dimethylimidazolidone, N, N, N',
Ureas such as N′-tetramethylurea; Sulfones such as dimethylsulfone and tetramethylenesulfone; Sulfoxides such as dimethylsulfoxide and diphenylsulfoxide; γ-butyrolactone,
Lactones such as ε-caprolactone; polyethers such as tetraglyme and 18-crown-6; nitriles such as acetonitrile and benzonitrile;
Examples include carbonate esters such as dimethyl carbonate and ethylene carbonate. Among the above catalysts, it is preferable to use aprotic polar solvents, ie, amines, amides, ureas, sulfones, sulfoxides, lactones, polyethers, nitriles, and carbonic esters. Particularly preferred are aprotic polar solvents with a dielectric constant of 20 or more. The reaction of the present invention can be carried out in either a homogeneous system or a heterogeneous suspension system. The reaction temperature is
Usually, conditions of 100 to 300°C are employed, but a more preferable temperature range is about 100 to 250°C. The reaction pressure used is 50Kg/ ^cm2 or higher, but usually
It is more common to carry out at about 150 to 600 Kg/ ^cm2 . This method can be carried out in any batch, semi-continuous or continuous reaction mode. Oxygen-containing compounds produced by the reaction, such as ethylene glycol and methanol, can be separated using normal separation methods.
For example, it can be separated by distillation. Furthermore, the distillation residue can be recycled and reused as a reaction catalyst liquid. [Examples] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. The amount of product produced is determined by the unit amount of rhodium atoms and the turnover number (mol/g-), which indicates the number of moles of product produced per unit reaction time.
atom7Rh・hr). Example 1 In a Hastelloy C autoclave with an internal volume of 35 c.c.
Tetrarhodium dotecacarbonyl [Rh ₄ (CO) ₁₂ ] containing 0.5 mg-atom of rhodium, 0.5 mmol of tri-iso-propylphosphine, trimethylamine-
0.5 mmol of N-oxide and 10 ml of N,N'-dimethylimidazolidone were charged, and a glass mixture of equal volumes of carbon monoxide and hydrogen was charged at room temperature to 300 kg/cm ² . The initial reaction pressure was 480 Kg/cm ² when the temperature of the autoclave was raised to 220°C. The reaction pressure is maintained in the range of 460 to 480 kg/cm ² by intermittently supplying an equal volume mixed gas of carbon monoxide and hydrogen.
The reaction was carried out at 220°C for 2 hours. After the reaction was completed, the autoclave was cooled and the contents were taken out and analyzed by gas chromatography.
It was confirmed that 17.9 mol/g-atom Rh/hr of ethylene glycol and 11.9 mol/g-atom Rh/hr of methanol were produced. Example 2 The amount of trimethylamine-N-oxide charged
The reaction was carried out in the same manner as in Example-1 except that the amount was changed to 5.0 mmol. As a result, 10.8mol/g-
atom Rh・hr ethylene glycol and 4.6mol/g
It was confirmed that -atom Rh・hr methanol was generated. Examples 3 to 8 and Comparative Example 1 The reaction was carried out in the same manner as in Example 1, except that the following amine-N-oxide was used instead of trimethylamine-N-oxide. The results are shown in Table-1.

[Table] Example 9 A reaction was carried out in the same manner as in Example 1, except that 0.5 mmol of phenanthroline-1-oxide was used instead of trimethylamine-N-oxide. As a result, ethylene glycol 11.6mol/g
-atom Rh・hr, methanol 17.3mol/g-atom
It was confirmed that Rh/hr was generated. Example 10 A reaction was carried out in the same manner as in Example 1, except that 0.5 mmol of dipyridyl dioxide was used instead of trimethylamine-N-oxide. As a result, ethylene glycol 16.1mol/g-atom
Rh・hr, methanol 13.0mol/g-atom Rh・hr
was confirmed to be generated. Examples 11-12 Table- instead of triiso-propylphosphine
The reaction was carried out in the same manner as in Example 1, except that the trialkylphosphine shown in Example 2 was used. The results are shown in Table-2.

[Table] Example 13 In a Hastelloy C autoclave with an internal volume of 35 c.c.
Tetrarhodium dodecacarbonyl [Rh ₄ (CO) ₁₂ ] containing 0.5 mg/atom of rhodium, 0.5 mmol of tri-iso-propylphosphine, 0.5 mmol of tripiperidinophosphine oxide, and N as a solvent.
After charging 10 ml of N′-dimethylimidazolidone, add a mixed gas of equal volumes of carbon monoxide and hydrogen at room temperature.
It was press-fitted up to 300Kg/cm ² . The initial value of the reaction pressure when the autoclave temperature is raised to 220℃ is 480
It was Kg/ ^cm2 . The reaction pressure is increased to 480 to 460 kg/kg by intermittently supplying an equal volume mixed gas of carbon monoxide and hydrogen.
The reaction was carried out at 220° C. for 2 hours while maintaining the temperature within the range of cm ² . After the reaction, the autoclave was cooled and the contents were taken out and analyzed by gas chromatography. As a result, 14.9 mol/g-atom Rh・hr of ethylene glycol and 21.88 mol/g-atom Rh・hr of methanol were produced. It was confirmed that Examples 14 to 17 The reaction was carried out in the same manner as in Example 13, except that phosphine oxide shown in Table 3 was used instead of tripiperidinophosphine oxide. The results are shown in Table-3.

[Table] Examples 18-20 Table 4 Using tri-n-octylphosphine oxide instead of tripiperidinophosphine oxide
The reaction was carried out in the same manner as in Example 13 except that the amount used was as shown in . The results are shown in Table 4.

[Table] [Effects of the Invention] According to the method of the present invention, it is possible to produce ethylene glycol at a high level of yield that could not be achieved using conventional catalyst systems.

Claims (1)

[Claims] 1. A method for producing ethylene glycol by reacting carbon monoxide and hydrogen in a liquid phase in the presence of a rhodium catalyst, characterized by the presence of trialkylphosphine and amine-N-oxide or phosphine oxide in the reaction system. A method for producing ethylene glycol.