DE2643971C3 - Process for the preparation of alkane polyols - Google Patents

Description

The invention relates to the production of alkane polyols, in particular of ethylene glycol, in a further development of the process according to US-PS 38 33 634.

These older methods relate to the reaction of hydrogen with carbon oxides in the presence of Rhodium carbonyl complexes as catalysts for the production of the alkane polyols mentioned. In a Another older application is the production of alkane polyols with the aid of rhodium carbonyl complexes in a homogeneous liquid phase using tetramethylene sulfone as the main solvent. Of the The main advantage of using a solvent in this older process is the reduction of Catalyst losses. According to an older suggestion, one already has tetraglyme as a solvent Process used in a homogeneous liquid phase (tetraglyme is the dimethyl ether of tetraethylene glycol).

It was surprisingly frame: that through Use of a mixture of tetraglyme and sulfolane gives higher degrees of conversion to alkane polyol can be obtained and optionally under more favorable process conditions and higher temperatures can work than is the case when using only tetraglyme or sulfolane as solvents.

The use of this solvent mixture in the reaction in a homogeneous liquid phase any working conditions gives higher yields of ethylene glycol than under the same working conditions using only one of these solvents while using all other ingredients including promoters are the same. It is also advantageous in the method according to the invention, that with increasing reaction temperature the rate constant the formation of alkane polyols increases. Another advantage is that this mixture is possible the adverse effect that can occur when only sulfolane is used on these is reduced Temperatures as the only solvent in terms of instability, which is detrimental to the catalyst activity influenced.

The process according to the invention is carried out at temperatures and pressures in the sense of those mentioned above Palente and registrations, namely at about 100 to 375 ° C and pressures from 35 to 3515 ata. That The ratio of tetraglyme to sulfolane is determined by the reaction conditions. Basically can it is said that the solvent ratio sought is such that the formation of alkane polyol is greater than with the individual solvents under the same conditions.

This ratio of tetraglyme to sulfolane ("solvent ratio") can be between 1:20 and 20: 1, based on the volumes. Factors such as the ratio of CO to H ₂ , temperature, pressure and the type of promoter play a certain role in determining the most effective solvent ratio. In one system the volume ratio of tetraglyme to sulfolane can be optimally 1, while in another system it is 2. When establishing a suitable solvent ratio, several ratios must be checked on the basis of a number of tests in a given reaction system in order to be able to determine optimal solvent ratios.

The term "sulfolane" here includes tetramethylene sulfone and substituted tetramethylene sulfone, which are the bring the same benefits. The substituted sulfolanes which can be used according to the invention correspond to general formula

R ₈ SR ₆
OO

wherein Ri to Re a hydrogen atom, a hydroxyl group, a straight or branched alkyl group, preferably with 1 to 12, in particular 1 to 6 carbon atoms (methyl, ethyl, isopropyl, butyl, dodecyl, octyl), a cycloaliphatic group (including monocyclic and bicyclic groups such as cyclopentyl, cyclohexyl, bicyclo- [2,2, l] heplyl) or an aryl, alkaryl or aralkyl group (phenyl, naphthyl, XyIyI, ToIyI, benzyl, O-phenylethyl) or an ether (-O —R ⁰ ), where R ^{0 is an} aryl or lower alkyl group with 1 to 12, preferably 1 to 4, carbon atoms in the alkyl chain, an alkyl or polyalkylene ether of the formula - (OC _n H ₂ ")" - OR ° where // on average is 1 to 4, A on average is 2 to 10, preferably 1 to 20, especially 1 to 4 and R ^{00 is a} hydrogen atom or an alkyl group with 1 to 6 carbon atoms (polyoxyethylene, polyoxypropylene, polyoxyethyleneoxypropylene, alkylene and polyalkylene glycols and lower alkyl ethers thereof, a carboxylate group of the formula

(CH ₂ ) ,. (()) ", C (C))" _llT R """

where y can be from 0 to 12 and m or nfi is 0 or 1 with bo with the proviso that when / 77 or nfi is 1, the other index is 0 and R ^{00 is} a lower alkyl group of 1 to 12, preferably 1 to 4 C atoms or an aryl group, with the proviso that not all of the substituents Ri to Re are hydrogen atoms).

Tetramethylene sulfone or tetrahydrothiophene U-dioxide are preferred for the process according to the invention. In the case of the substituted sulfolanes, the positions 3 or 3, 4 are preferred.

Rhodium carbonyl complexes for the process according to the invention are complex compounds, at least one of which is complexed with 1) rhodium with CO; 2) rhodium complexed with CO and H ₂ ; 3) Rhodium complexed with CO and at least one Lewis base and / or rhodium complexed with CO, Ht and at least one Lewis base.

The rhodium carbonyl complexes for the process according to the invention can be cluster compounds (P. C h i π i, "The Closed Metal Carbonyl Clusters", [1968], Inorganica Chimica Acta, pages 30-50), after which a Metal cluster compound is a limited group of metal atoms that are completely, principally, or held together at least to a substantial extent by direct metal-to-metal bonding, though some non-metal atoms can also be assigned as closely as possible to the cluster. The rhodium carbonyl cluster compounds, which are to be used in the process according to the invention contain Rh / Rh or Rh / other metal bonds such as cobalt and / or iridium. The preferred compounds are those with Rh / Rh bonds. They preferably contain Carbon and oxygen in the form of a carbonyl group (—CO-), these being terminal, at the edge or can lie in the area. You can use hydrogen (oxygen) and carbon, but also in other than Contain carbonyl form. These cluster connections can be assigned to the following formulas.

[Rh ₁₂ (CO) ₃₀ ]

2-

The structures of these cluster compounds can be determined with the aid of X-ray crystal analysis, magnetic resonance spectrum or infrared spectrum ("Synthesis and Properties of the Derivatives of the [RhI ₂ (CO) ₃₀ ] ² Anion", P. C hi η i and S. Martineng o, Inorganica Chimica Ada, 3: 2, ropes 299-302, June 1969). Particularly suitable for the analysis is the infrared spectral analysis, which characterizes the complexes present during the conversion according to the method according to the invention.

In the complex, CO is present in complex-bound form on rhodium. To form the complex can but also additionally hydrogen atoms and / or organic or inorganic Lewis base promoters to serve. In the latter case it is a question of coordination compounds by combining one or more electron-rich molecules or atoms, which are also able to exist independently, with one or more low-electrolyte molecules or atoms, which are also viable independently. The role that the Lewis bases play in the implementation according to the play method according to the invention has not yet been fully elucidated. They can act as a ligand and / or form counterions under reaction conditions or they can only act as Lewis bases and Neutralize or capture a special type of molecule that, if left free or not bound to the base could adversely affect the formation of alkane polyols according to the invention.

Organic Lewis bases for the purpose according to the invention contain at least one Lewis base -02 and / or -N ⁽ 2, which have an electron pair which is capable of a coordinate bond. Thus, the Lewis bases 1 to 4 Lewis- Contain base atoms, preferably 1 to 3, in particular 1 or 2. Such Lewis bases are plural (2-, 3- or 4-toughened, depending on whether 2, 3 or 4 Lcwis base atoms

^r > o are included).

Lewis bases with both a nitrogen and at least one oxygen stream are referred to as aza-oxa Lewis bases.
Aza Lewis bases generally contain C, H and N atoms, oxa Lewis bases C, H and O atoms, and the aza-oxa Lewis bases C, H, O and N atoms. The carbon atoms can be acyclic and / or cyclic, such as aliphatic, cycloaliphatic or aromatic, including condensed and bridged systems. the

bo preferred Lewis bases contain 2 to 60, in particular 2 to 40 carbon atoms. The nitrogen atoms can be present in the form of the imino, amino or nitrile group be. However, the imino and / or amino nitrogen group is preferred. The oxygen atoms can be in

b5 form of an alcoholic phenolic hydroxyl group, a carboxyl group, a carbonyloxy, an oxy or carbonyl group. All these Groups contain Lewis base oxygen atoms.

The hydroxyl oxygen in the carbonyl group and they are the oxy-oxygen in the carbonyloxy groups Lewis base atom. The organic Lewis bases can also contain further atoms and / or groups as substituents such as alkyl, cycloalkyl, aryl, chlorine or trialkylsilyl.

Examples of oxa Lewis bases are glycolic acid, methoxyacetic acid, Ethoxyacetic acid, diglycolic acid, ethyl ether, tetrahydrofuran, dioxane, tetrahydropyran, pyrocatechol, Citric acid, 2-methoxyethanoI, 2-ethoxyäiiianol, 2-n-propoxyethanol, 2-n-butylethanol, 1,2,3-trihydroxybenzene,

1,2,4-trihydroxybenzene, i-:

2,3-dihydroxynaphthalene,

Cyclohexane-l ^ -diol,

Oxetane, 1,2-dimethoxybenzene,

1,2-diethoxybenzene, methyl acetate, ethanol, i, 2-dimethoxyethane, 1,2-diethoxyethane, 1,2-di-n-propoxyethane, 1,2-di-n-butoxyethane, pentane-2,4-dione, hexane-2,4-diGn, heptane-3,5-dione, Octane-2,4-dione, 1-phenylbutane-1,3-dione, 3-methylpentane-2,4-dione; Mono- and dialkyl ethers of propylene glycol,

Diethylene glycol, dipropylene glycol. Examples of aza-qxa bases are

Alkanolamines (ethanolamine,

Diethanolamine, isoproanolamine, di-n-propanolamine): N, N-dimethylglycine, N, N-diethylglycine, iminodiacetic acid, N-methyldiiminodiacetic acid,

N-methyl diethanolamine,

2-hydroxypyridine, 2,4-dihydroxypyridine, 2-methoxypyridine, 2,6-dimethoxypyridine, 2-ethoxypyridine,

lower alkyl-substituted hydroxypyridines (such as 4-methyl-2-hydroxypyridine, 4-methyl-2,6-dihydroxypyridine), morpholine, substituted morpholines (such as 4-methylmorpholine,

4-phenylmorpholine).

Picolinic acid,

methyl-substituted picolinic acid, nitrilotriacetic acid,

2,5-dicarboxypiperazine,

N- (2-Hydroxyälhyl) -iminodjacetic acid, ethylenediaminetetraacetic acid,

2,6-dicarboxypyridine, 8-hydroxyquinoline, 2-carboxyquinoline, Cyclohexane-i ^ -diamine-

Ν, Ν, Ν ', Ν'-tetraacetic acid,

Tetramethyl ester of

Ethylenediaminetetraacetic acid.

Examples of aza Lewis bases are ammonia and amines.

Primary, secondary and tertiary organic amines including mono- and polyamines (mono-, di-, Tri- and polyamines) and Lewis bases, the nitrogen atoms of which are part of a ring structure as in pyridine, Quinoline, pyrimidine, morpholine and hexamethylenetetramine. Generally speaking, any connection is suitable, which is able to form an amino nitrogen like an amide under the reaction conditions (Formamide, cyanamide), urea or an oxime. Other Lewis bases with nitrogen atoms are aliphatic Amines

(such as methylamine, ethylamine, n-propylamine, isopropylamine, octylamine, dimethylamine, Diethylamine, diisoamylamine,

Methylethylamine, diisobutylamine, trimethylamine, methyl diethylamine, Triisobutylamine, tridecylamine), aliphatic and aromatic di- and Polyamines (such as 1,2-ethanediamine, 1,3-propanediamine,

Ν, Ν, Ν ', Ν'-tetramethylenediamine, Ν, Ν, Ν', Ν'-tetraethylethylenediamine, Ν, Ν, Ν ', Ν'-tetra-n-propylethylenediamine, Ν, Ν, Ν ', Ν'-tetrabutylethylenediamine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, p-tolylenediamine, o-toliden, N, N, N ', N'-tetramethyll-phenylenediamine,

N, N, N \ N'-Tetraethyl-4,4'-biphenyldiamine), aromatic amines

(such as aniline, 1-naphthylamine,

2-naphthylamine, p-toluidine,

o-3-xylidine, p-2-xylidine,

Benzylamine, diphenylamine,

Dimethylaniline, diethylaniline,

N-phenyl-1-naphthylamine,

bis- (l, 8) dimethylaminonaphthalene), alicyclic amines (such as cyclohexylamine, Dicyclohexylamine),

heterocyclic amines (such as piperidine) and substituted piperidines

(such as 2-methylpiperidine, 3-methylpiperidine,

4-Ethylpiperidine and 3-Phenylpiperidine, Pyridines and substituted pyridines (such as 2-methylpyridine,

2-phenylpyridine, 2-methyl-4-ethylpyridine, 2,4,6-trimethylpyridine, 2-dodecylpyridine, 2-chloropyridine and

2- (dimethylamino) pyridine),

Quinolines and substituted quinolines (such as 2- (dimethylamino) -6-methoxyquinoline, 4,5-phenanthroline, 1,8-phenanthroline, 1,5-phenanthroline), piperazines

and substituted piperazines

(such as N-methylpiperazine,

N-ethylpiperazine,

2-methyl-N-methylpiperazine,

2,2'-dipyridyl, methyl or

ethyl-substituted 2,2'-dipyridyl, 4-triethylsilyl-2,2'-dipyridyl>,

1,4-diazabicyclo [2.2.2] octane

and methyl substituted

1,4-diazabicyclo [2.2.2] octane and purine. Examples of inorganic Lewis bases are ammonia, Hydroxides and halides, such as the chlorides, bromides, iodides and / or fluorides.

Any of the above Lewis bases can be complexed as a compound or as ligands to the Rhodium carbonyl compound, which is the catalyst in the reactor at the beginning, be present.

The special role of rhodium carbonyl complexes such as rhodium carbonyl cluster compounds in the The reaction of hydrogen with carbon oxides with the formation of polyhydric alcohols has not yet occurred completely cleared up. Under the reaction conditions, the carbonyl complex may be in its anionic form. It is known that rhodium carbonyl anions are formed according to the following reaction system formed (S. Martinengo and P. Chiηi, in Gazz.

Chim.ltal., 102,344,1972).

Vi it ft t?

[Rh, ₂ (CO) _J4 _ _3f ,] ² - ^ [Rh ₁₂ (CO) ₃₁ J] ² - [Rh ₆ (CO) ₁₅ ] ² - + [Rh ₆ (CO) ₁₄ ] ⁴
I [Rh (CO) ₄ ] - \

(V)

CO ^v

[Rh ₆ (CO) ₁₅ ] ² - [Rh (CO) ₄ ] - -f CO [Rh ₇ (CO) ₁₆ ] ³ - <- [Rh ₄ (CO) ₁₁ ] ² "+ [Rh (CO) ₄ ]

* electron ^

The infrared spectrum under reaction conditions shows the anions Rh (COJi and [Rh ₁₂ (CO) ₃₄ -Sb] ² "and other rhodium cluster compounds at different concentrations at different times of the reaction. Therefore, the reactions and equilibria shown in (V) show the active form of rhodium carbonyl, which is responsible for the formation of polyhydric alcohols or which is only symptomatic of intermediate and transition structures that occur during the conversion of carbon monoxide and hydrogen to polyhydric alcohols.

Assuming that the active catalyst is the rhodium carbonyl complex anion or that the formation of the active catalyst under the reaction conditions depends directly on the existence of these Anions, so can with regard to the reaction rates, production and catalyst stability the role of sulfone solvents. especially the Tetramethylene sulfones, explain the reaction. It can be assumed that the sulfones the Improve the reactivity of these complex rhodium carbonyl anions, as they are a "naked" reactive anion is formed. The naked rhodium carbonyl anions are possibly under the reaction conditions formed because the sulfone solvent has any tendency for the rhodium carbonyl anion to form a Ion pair decreases. The rhodium carbonyl anions are not strongly solvated. also becomes rhodium not strongly complexed by the solvent. This results in an anion with a higher one Reactivity under reaction conditions.

The process according to the invention can be carried out within a wide upper pressure range, such as from about 56 to 3515 ata. Pressures over 3515 ata can be used, but are of no use; preferred the pressure does not go higher than about 3515 ata.

In one embodiment of the invention Procedure, the upper pressure limit is 1125 ata. If the method is carried out at a pressure below about 1125 ata, in particular below about 914 ata, in particular below about 562 ata, you only need low-pressure systems, but the conversion speed is at pressures below about 843 ata relatively slow and to speed up the implementation and / or for higher degrees of conversion a promoter is required which is a salt and / or a Lewis nitrogen base can be. In cases where the Lewis nitrogen compound is used as the Lingand in the catalyst abandoned rhodium carbonyl complex is present or where the anion of the promoter, which in the reactor is given, a rhodium carbonyl complex, such as cesium triacontacarbonyl rhodate, it is not necessary still apply further parts of this promoter. A useful working pressure for a procedure using these promoters is 70 to 1125 ata, preferably 281 to 1125 ata.

In the preferred method of the present invention, the above pressures are total pressures of carbon oxides and hydrogen in the reactor.

For the process of the invention at pressures below about 1125 ata one can use any organic or inorganic salts, as long as they do not adversely affect the formation of polyhydric alcohols, use.

In a preferred embodiment of the process according to the invention, the above pressure specifications apply understand the total pressure of hydrogen and carbon oxides in the reactor.

The process according to the invention is optionally carried out in a homogeneous liquid reaction mass which contains salts. Organic and inorganic salts which do not impair the formation of polyhydric alcohols are suitable as salts. The test results suggest that any salt can be advantageous as a co-promoter and / or to keep the rhodium in solution during the reaction. Examples are ammonium salts and the alkali and alkaline earth salts (salts of metals I. and II. Group of the periodic table) such as the halides, hydroxides, alkoxides, phenoxides and carboxylates, in particular sodium, cesium fluoride, cesium pyridinolate, cesium formate, acetate or benzoate, Cesium p-methylsulfonylbenzoate (CH ₃ SO ₂ C ₆ H ₄ -COO) Cs, rubidium, magnesium or strontium acetate, ammonium formate or benzoate. Preference is given to cesium or ammonium carboxylates, in particular formate and benzoate and para-lower alkyl-substituted sulfonyl benzoates.

Organic salts of the formulas can also be used:

R,

R ₄ -NR ₂

R ₃

(Π)

quaternary ammonium salts

R ₅ -P = N = PR ₂

(1Π)

R ₄ R ₃

bis (triorganophosphine) iminium salts
wherein R ₁ to R _{6 are} organic groups such as straight-chain

or branched alkyl groups with 1 to 20 carbon atoms (methyl, ethyl, propyl, butyl, octyl, 2-ethylhexyl, dodecyl) or cycloaliphatic groups including monocyclic and bicyclic groups (cyclopentyl, cyclohexyl, bicyclo [2,2, l] heptyl groups) or aryl, alkaryl or aralkyl groups (phenyl, naphthyl, xyIyI, ToIyI, t-butylphenyl, benzyl, / 3-phenylethyl, 3-phenylpropyl) or functionally substituted alkyl groups (/ 3-hydroxyethyl, ethoxymethyl, ethoxyethyl, phenoxyethyl) or polyalkylene groups of the formula in (—C _n Hj _n O) ₁ -OR, in which π is on average 1 to 4, λ 'is on average 2 to about 150 and R is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, such as poly (oxyethylene ), Poly (oxypropylene), poly (oxyäthylenoxypropylen), poly (oxyathy! Enoxybuty! En). Y can be any anion such as in hydroxide, halide (fluoride, chloride, bromide, iodide), a carboxyl group (formate, acetate, propionate, benzoate), an alkoxy group (methoxy, ethoxy, phenoxy), a functionally substituted alkoxy or phenoxy group (Methoxyethoxy, methoxyethoxy, phenoxyethoxy) or a pyridinolate or quinoate group. Y is preferably a carboxylate group, in particular formate, acetate or benzoate.

The production of bis (triorganophosphine) iminium salts is known (A ρ ρ e 1, R. and H a η a s, A. in Z. Anorg. and AIIg. Chem., 311,290,1961).

Other useful organic salts are quaternized heterocyclic amine salts (pyridinium, piperidinium, Morpholinium or quinolium salts such as N-ethylpyridinium fluoride,

N-methylmorpholinium benzoate,

N-phenylpiperidinium hydroxide,

N, N'-dimethyl-2,2-bipyridinium acetate).
In addition to the anion of the above salts, Ά the anions of the rhodium carbonyl complex can also serve as

[Rh ₅ (CO) ₁₅ ? , [Rh ₆ (CO) ₁₅ Y],
wherein Y is a halogen atom (chlorine, bromine, iodine), or
[Rh ₆ (CO) ₁₅ (COOR "] -, where R" is a lower alkyl or aryl group (methyl, ethyl, phenyl),
[Rh ₆ (CO) ₁₄ ] ² -, [Rh ₇ (CO) ₁₆ ? - [Rh ₁₂ (CO) ₃ O? -.

If the salt is added to the initial batch of the reactants, then one reckons with about 0.5 to 2 mol, preferably 0.8 to 1.6 mol, in particular 0.9 to 1.4 mol of salt per 5 atoms of Rh in the reaction mixture.

The above aza- or aza-oxa-Lewis bases can be used as promoters in the form of Lewis nitrogen bases use. Amines are preferred. The nitrogen atom can be part of a heterocycle, such as of pyridine, Pyrimidine, piperidine, morpholine or quinoline. To be favoured

Pyridine, 2,4,6-trimethylpyridine,

4-dimethylaminopyridine, 4-tridecylpyridine, isobutylamine,

Triethylamine, N-methylpiperidine,

N-methylmorpholine,

bis- (l, 8) -dimethylaminonaphthalene,

1,4-diazabicyclo (2 ^ 2) octane t> o

and quinuclidine.

Lewis nitrogen bases as a promoter are preferably used in an amount of about 0.02 to 2 Equivalent, in particular 0.1 to 1 equivalent, per mole Rhodium in the reaction mass. The number of equivalents of promoter is equal to the number of moles Promoter multiplied by the number of nitrogen atoms in each molecule.

Mixtures of the above salts and amines as promoters for low working pressures can be used according to the invention can be applied. The promoters are used in the reaction in the form of the compounds or es substances are introduced into the reactor which are in situ either before or during the implementation of the Process according to the invention capable of forming salt and / or amine as a catalyst, such as an amide ζ. B. formamide or urea or an oxime which can be used as a promoter instead of an amine. Preferred promoters for lower working pressures are trialkanolamine borates, in particular those of the formula

wherein R ₁₁ , Rf, and R, - can be a hydrogen atom or a lower alkyl group with 1 to 12 carbon atoms in the chain. Triethanolamine borate and triisopropanolamine borate are particularly preferred.

The amount of the analyzer is not critical and can vary over a wide range. One can levels as low as about 1 wt .-% χ 10- ⁶ or less, given as rhodium metal, applied in the total weight of the reaction mass. The upper limit of the concentration can be quite high, e.g. B. 30 wt .-% Rh and above. The actual upper limit to be applied depends primarily on the cost of rhodium metal and rhodium compounds from an economic point of view. Depending on various factors, such as the choice of promoter, partial pressures of hydrogen and carbon oxides, working pressure, working temperature, choice of the second solvent and other conditions, a catalyst concentration of about 1 χ 10 ⁵ to 5% by weight of Rh contained in the complex is based on the total weight of the reaction mass, proved to be appropriate.

The reaction temperature can fluctuate within wide limits of elevated temperatures. In general one works at about 100 to 375 ° C or above. At lower temperatures, the reaction rate becomes or implementation noticeably slower; at higher temperatures and above the specified Temperature can lead to catalyst instability, but the reaction continues and Alkane polyols and / or their derivatives are formed The equilibrium reaction is also with the formation of Consider ethylene glycol

2CO + 3H ₂

^ HIGH ₂ CI-UOH

At relatively high temperatures, the equilibrium is shifted more and more to the left. In order to shift the reaction to increasing amounts of ethylene glycol, higher partial pressures of carbon monoxide and hydrogen are required. Processes with correspondingly higher pressures are not preferred because of the high investment costs for the system. Suitable temperatures are about 150 to 320 ° C, in particular 210 to 300 ⁰ C.

As a dwell time for the process according to the invention

you can count on a few minutes to several hours, e.g. B. a few minutes to about 24 hours. the Residence time is influenced to a marked extent by the reaction temperature, the concentration and the selection of the catalyst, the total gas pressure and the partial pressures, the concentration and the Choice of diluent, etc. The synthesis of the desired products by converting hydrogen with carbon oxide is expediently carried out under working conditions that allow appropriate reaction rates and / or receive conversions.

The relative amounts of carbon oxide and hydrogen in the reaction mixture at the start of the process can vary widely. In general, a CCVH ₂ molar ratio of about 20:! until ! : 20 on, 10: 1 to 1:10 is preferred. in particular 5: 1 to 1: 5.

In principle, other molar ratios can also be used. Substances and reaction mixtures which form carbon monoxide or hydrogen under the reaction conditions can also be used instead of the initial gas mixture CO + H ₂ . In this way, polyhydric alcohols are also obtained from mixtures containing CO2 and H ₂ . Mixtures of CO2, CO and H ₂ can also be used; finally also a mixture of steam with CO.

The process according to the invention can be carried out batchwise, semicontinuously or continuously. The reaction can take place in a single or in several reaction zones or in a tubular reactor. The reaction zone can be provided with internal and / or external heat exchangers in order to avoid undue temperature fluctuations or even a runaway of the exothermic reaction avoid. It is also preferred to stir. The catalyst can be introduced into the reaction zone batchwise at the beginning or continuously or intermittently.

In the continuous process z. B. if preferred will work at relatively low levels of conversion, it is generally desirable not to to recirculate converted synthesis gas, if necessary with fresh carbon oxide and hydrogen. The extraction the desired products can be done in the usual way such as by distillation, fractionation, Extraction or the like. One the rhodium catalyst in by-products and / or the normally liquid The fraction containing diluents can be recycled or completely or partially for work-up the rhodium content or to regenerate the active catalyst and from time to time in give up the reflux stream or directly into the reaction zone.

The active forms of the catalyst can be obtained in a number of ways. So you can Prepare the catalyst and then introduce it into the reaction zone. But you can also use rhodium-containing Introduce substances as well as promoters for low working pressures into the reaction zone and below Operating conditions including the presence of hydrogen and carbon monoxide the active Form rhodium carbonyl cluster compounds in situ. Examples of useful rhodium-containing starting substances are

Rhodium oxide (Rh ₂ Oa),
Tetrarhodium dodecarbonyl,
Dirhodiumoclacarbonyl,
HexarhodiumhexadecacarbonylfRh ^ CO) ^),

Rhodium (II) format, acetate, propionate.
-bulyrate, -valerate, -naphthenate,
Rhodium dicarbonylacetylacetonate,
Rhodium tr ^ acetylacetonate),
Rhodium trihydroxide,

indenyl rhodium dicarbonyl,
Rhodium dicarbonyl- (1-phenylbutane-1,3-dione),
tris (hexane-2,4-dionato) rhodium (IIi),
tris (heptane-2,4-dionato) rhodium (III),
tris (3-methylpentane-2,4-dionato) rhodium (III),

tris (1-cyclohexylbutane-1,3-dionato) rhodium (III),

Triacontacarbonylrhodium salts

and rhodium-containing compounds on porous supports, form the rhodium carbonyls in solution.

The rhodium carbonyl complex compounds are expediently prepared in the solvent mixture. Because of its limited solubility, finely divided tetrarhodium dodecacarbonyl can be added to the solvent. The above rhodium compounds can be used instead of tetrarhodium dodecacarbonyl. Organic Lewis bases such as pyridine and other promoters such as the above salts can be added. The complex-forming reaction can take place under carbon monoxide pressure (optionally with hydrogen) of about 1 to 15 atmospheres or above and at temperatures between about JO and 100 ^° C. in a few minutes to a few days, generally from about 30 minutes to 24 hours. The complex in the solvent mixture is catalytically active for the process according to the invention. In the preparation of the above complexes, about 0.01 to 25 mol of salt or Lewis nitrogen base can be used as promoters per mol of rhodium j5. Other ratios are useful, particularly when dilution amounts of the low pressure promoters are used.

A device and the measure for determining the presence of anionic rhodium carbonyl complexes or clusters with a well-defined infrared spectrum during the reaction according to the invention Procedures are described in the earlier application above. It is particularly suitable as an infrared cell such according to US-PS 38 86 364.

In addition to carbon monoxide, “carbon oxide” is also understood here to mean a mixture of carbon dioxide and carbon monoxide, either as it is introduced directly into the reaction or as it is formed in the reaction. However, preference is given to using carbon monoxide.
The invention is further illustrated by the following examples.

To analyze the reactor contents for the rhodium content, the reactor was ^{rinsed with 100 cm J} solvent, the contents brought to 160 ° C and a pressure of 984 to 1054 and left there for 30 min, then cooled, unreacted gas vented and the rhodium content determined again . The rhodium values are in the following tables in%, based on the total rhodium used, given as dissolved or suspended rhodium used and proportion in the washing liquid

The substances used in the examples had the following characteristics:

Cesium benzoate, recrystallized from water,
Analysis:

Found:

32.62% C and
1.9% H,

calculated on
C ₇ H ₅ O ₂ Cs:

33.1% C and

1.98% H;

Triisopropanolamine borate m.p. 155-157 ° C; P-MeSO ₂ C ₆ H ₄ CO ₂ Cs
Cesium p-methylsulfonyl benzoate recrystallized from H ₂ O.
Analysis:

Found: 28.26% C, 2.05% H; calculated on

C ₈ H ₇ O ₄ SCs: 28.9% C, 2.13% H.

In a 150 cm ³ reactor made of corrosion-resistant steel for a maximum pressure of 7000 atü, a yor mixture of 75 cm ³ solvent mixture, a certain amount of rhodium dicarbonylaeetylacetonate and certain proportions of amine, borate and salt as promoters were introduced, the reactor was closed and an equimolar gas mixture of CO and H ₂ pressed in. As soon as the temperature had reached 190 ^° C., the working pressure was set to 562 atmospheres and the temperature and pressures were maintained in accordance with the table below.

When the reaction had ended, the mixture was cooled to room temperature, excess pressure was released and the reaction product discharged. The analysis of the reaction products was carried out by gas chromatography. the The yield of ethylene glycol and methanol as well as the recovery of the rhodium are shown in the table summarized.

Table

Examples

The following examples show that a mixture of sulfolane and tetraglyme leads to higher conversion, as a pure solvent (Examples 1 to 27, 32 and 33). It can also be seen that the implementation of the invention is better in many cases than with any of them pure solvent (examples 1-15). Finally, they show the increase in the amount of sulfolane required for good recovery of rhodium with increasing temperature (Examples 12 to 15 compared to 1 to 11, 26 and 27 compared to 28, 29 and 30, 31 as well as examples 32, 33 compared to 34, 35 and 36 to 38). Even This list shows the need for higher pressures for good rhodium recovery

! 5 with increasing temperature with constant solvent ratio (Examples 1 to 15 and 18 to 20 versus up to 40 and 28 to 31).

The rhodium recovery and thus the conversion to glycol is determined by the 3-fold effect the solvent ratio, pressure and temperature. So that the rhodium stays in solution with increasing Temperature and glycol is formed at a higher rate, it is necessary that the solvent ratio increases or decreases. This is a more imperative for lower pressures. With increasing Temperature or falling pressure one reaches a point at which only by changing the solvent ratio no high recovery of rhodium can be achieved.

example

Relation

Sulfolane /

Tetraglyme

pressure

(psi)

kg / cm ²

Temp. Mole Rh mole promoter

100/0
76/24
54/46
36/64
17/83
0/100

100/0
76/24
54/46
36/64
17/83

(8000) 562

(8000) 562

(8000) 562

(8000) 562

(8000) 562

(8000) 562

(8000) 562

(8000) 562

(8000.) 562

(8000) 562

(8000) 562

240 240 240 240 240 240

240 240 240 240 240

12th 100/0 (8000) 562 260 3 13th 76/24 (8,000) 562 260 3 14th 50/50 (8000) 562 260 3 15th 24/76 (8000) 562 260 3 16 100/0 (8000) 562 240 3 17th 76/24 (8000) 562 240 3 18th 100/0 (8000) 562 260 3 19th 76/24 (8000) 562 260 3 20th 50/50 (8000) 562 260 3 21 50/50 (15000) 1054 240 .3 22nd 13/87 (15000) 1054 240 3 23 0/100 (15000) 1054 240 3

Cs-benzoal 0.65
Cs benzoate 0.65
Cs-benzoal 0.65
Cs benzoate 0.65
Cs-benzoal 0.65
Cs benzoate 0.65

Pyridine 0.63
Pyridine 0.63
Pyridine 0.63
Pyridine 0.63
Pyridine 0.63

Ethylene dimorpholine 7.0
Ethylenedimofpholine 7.0
Ethylene dimorpholine 7.0
Ethylene dimorpholine 7.0

N-methylmorphoHn 5.0
N-methylmorphoHn 5.0

Cs formate 0.65 triisoproparolamine borate 2.5 Cs formate 0.65 triisoproparolamine borate 2.5 Cs formate 0.65 triisoproparolamine borate 2.5

Cs benzoate 0.65 triisoproparolamine borate 2.5 Cs benzoate 0.65 triisoproparolamine borate 2.5 Cs benzoate 0.65 triisoproparolamine borate 2.5

15th

continuation

At- Relative pressure

game Sulfolane /

Tetraglyme (psi)

kg / cm ² temp.
C.

Mole Rh mole promoter

24 100/0 (15000) 1054 25th 50/50 (1500) 1054 26th 24/76 (15000) 1054 27 0/100 (15000) 1054 28 50/50 (15000) 1054 29 24/76 (15000) 1054 30th 50/50 (15000) 1054 31 24/76 (15000) 1054 32 0/100 (12500) 879 33 24/76 (12500) 879 34 24/76 (12500) 879 35 50/50 (12500) 379 36 24/76 (12500) 879 37 50/50 (12500) 879 38 60/40 (12500) 879 39 24/76 (12500) 879 40 50/50 (12500) 879

Tabel example

3 ethylene dimorpholine 7.0

3 ethylene dimorpholine 7.0

3 Cs benzoate 0.75 pyridine 1.25

1.5 Cs benzoate 0.375 pyridine 1.25

1.5 Cs benzoate 0.375 pyridine 1.25

■ 1.5 Cs benzoate 0.375 pyridine 1.25

1.5 Cs benzoate 0.375 pyridine 1.25

1.5 Cs benzoate 0.375 pyridine 1.25

6 Cs benzoate 1.5 pyridine 2.5

6 Cs benzoate 1.5 pyridine 2.5

3 Cs-Benzcat 0.75, pyridine 1.25

3 Cs benzoate 0.75 pyridine 1.25

1.5 Cs benzoate 0.375 pyridine 1.25

1.5 Cs benzoate 0.375 pyridine 1.25

1.5 Cs benzoate 0.375 pyridine 1.25

3 Cs-p-methylsulfonyl benzoate 0.75 Triisoproparolamine borate 2.5

3 Cs-p-methylsulfonyl benzoate 0.75 Triisoproparolamine borate 2.5

Methanol moles / h

(G)

Ethylene glycol moles / h

(8) recovery
% Rh

reactor

To wash

Gas uptake (CO + H ₂ ) (psi)

kg / cm ²

Response time h

1 0.31 (3.0) 0.23 (4.2) 2 0.29 (2.8) 0.22 (4.0) 3 0.31 (3.0) 0.28 (5.2) 4th 0.34 (3.3) 0.26 (4.9) 5 0.36 (3.5) 0.26 (4.9) 6th 0.23 (2.2) 0.16 (2.9) 7th 0.29 (2.8) 0.24 (4.5) 8th 0.27 (2.6) 0.35 (6.5) 9 0.23 (2.7) 0.29 (5.3) 10 0.27 (2.6) 0.28 (5.2) 11th 0.27 (2.6) 0.13 (2.4) 12th 0.54 (5.2) 0.38 (7.1) 13th 0.57 (5.5) 0.38 (7.1) 14th 0.62 (6.0) 0.41 (7.7) 15th 0.25 (2.4) 0.06 (1.1) 16 0.37 (3.6) 0.29 (5.3) 17th 0.32 (3.1) 0.31 (5.7)

6th
10
11
20th
21
52

6th
6th
10
5
0

7th
8th

(230Ö)
(3250)
(2950)
(2850)
(3150)
(2100)

(3000)
(3750)
(3500)
(2850)
(1700)

(5600)
(6500)
(6000)
(2050)

(4300)
(4200)

197 228 207 200 221 148

211 264 246 200 119

394 457 422 144

302 295

4.0 4.0 4.0 4.0 4.0 4.0

4.0 4.0 4.0 4.0 4.0

4.0 4.0 4.0 4.0

4.0 4.0

030 207/352

Methanol 17th Ethylene glycol 26 43 971 To wash 18th (PSi) E. Moles / h Moles / h 10 (G) (E) 6th Gas intake 288 I. 0.47 (4.5) 0.32 (6.0) Recovery 12th (CO + H ₂ ) 323 Response time f continuation 0.57 (5.5) 0.35 (6.5) % Rh 6th kg / cm ³ 394 example 0.60 (5.8) 0.39 (7.2) reactor 5 (4100) 439 Hi 1.1 (1.7) 2.1 (6.3) 77 8th (4600) 576 4.0 1.6 (4.7) 2.0 (11.7) 77 6th (5600) 429 4.0 1 18th 1.6 (3.6) 1.4 (6.2) 53 6th (6250) 422 4.0 I. 19th 3.1 (4.1) 2.9 (7.4) 102 6th (8200) 513 0.65! 20th 2.7 (5.4) 3.7 (14.2) 82 14th (6100) 548 1.25 j 21 3.1 (3.7) 4.9 (11.4) 69 6th (6000) 422 0.96] 22nd 1.7 (3.7) 2.0 (8.4) 107 7th (7300) 422 0.55 23 2.7 (4.3) 3.2 (10.6) 91 16 (7800) 285 0.83 I. 24 2.9 (2.5) 4.1 (6.9) 83 25th (6000) 450 1.00 I. 25th 4.3 (5.9) 4.4 (11.8) 70 11th (6000) 422 0.45 I. 26th 3.2 (5.8) 2.7 (9.4) 80 6th (4050) 422 0.67 j 27 3.1 (6.5) 2.4 (9.8) 76 5 (6400) 432 0.36 \ 28 5.8 (8.0) 3.4 (9.2) 76 6th (6000) 422 0.58 j 29 3.0 (5.7) 2.6 (9.9) 39 36 (6000) 422 0.76 ι 30th 2.9 (5.5) 2.7 (9.8) 78 13th (6150) 281 0.88 1 31 0.35 (3.5) 0.25 (5.3) 85 17th (600) 281 0.58 S 32 1.7 (3.8) 1.7 (7, J) 92 41 (6000) 281 0.80 I. 33 2.0 (4.0) 1.7 (6.8) 98 16 (4000 422 0.77 i 34 2.4 (6.3) 1.9 (9.8) 19th (4000) 422 4.18 35 2.0 (5.5) 1.7 (8.9) 81 (4000) 0.95 I. 36 78 (6000) 0.85 y 37 29 (6000) 1.08 I. 38 44 1.16)
i 39 40

Claims (1)

Claim: Process for the preparation of alkane polyols, in particular ethylene glycol, by reaction of carbon oxides and hydrogen in the presence of a rhodium complex catalyst in a homogeneous liquid phase at about 100-375 ° C and a pressure of about 70-3515 ata, characterized in, that the reaction is carried out in a solvent mixture of tetraglyme and sulfolane, the solvent ratio is chosen so that the formation of alkane polyol is greater than under similar conditions using only one solvent.