KR20020019602A - Method of Producing Carboxylic Acids by Carbonylation of Olefins - Google Patents

Abstract

The present invention relates to a process for preparing carboxylic acids based on olefins and carbon monoxide in the presence of water. The process of the present invention is a catalyst system that does not contain halogens: a) rhodium or rhodium compounds, b) at least one nitrogen-containing heterocyclic compound, c) at least one alkali metal of aliphatic C ₂ -C ₂₀ -carboxylic acid Salts or alkaline earth metal salts and d) mixtures of at least one glycol ether of the formula (I).

<Formula I>

Wherein R ¹ and R ² are independently C ₁ -C ₂₀ -alkyl or R ³ CO, wherein R ³ is hydrogen or C ₁ -C ₂₀ -alkyl, or R ¹ and R ² together are C ₁ -C Forms a ₂₀ -alkylene chain, n is 1 to 30;

Description

Method for Producing Carboxylic Acid by Carbonylation of Olefin {Method of Producing Carboxylic Acids by Carbonylation of Olefins}

The present invention relates to 30 to 30 in the presence of a catalyst system containing no olefin and carbon monoxide in the presence of water and a halogen comprising a rhodium or rhodium compound, a nitrogen containing compound, an alkali metal carboxylate or a mixture of alkaline earth metal carboxylates and glycol ethers. A method for producing a carboxylic acid or ester thereof by reacting at 150 ° C. and a pressure of 30 to 150 bar.

(Industrielle Organische Chemie, 1994, 4th edition, Verlag Chemie, pp. 153-154, Weissermel et al.) Describe the carbonylation of olefins by the Reppe process, for example from ethylene, carbon monoxide and water in the presence of a catalyst. It describes the preparation of propionic acid. The catalyst used is nickel propionate which is converted to nickel carbonyl under the reaction conditions. High ethylene conversion is only achieved at high pressures (200-240 bar). These reaction conditions require the manufacture of expensive and suitable reactors and require special and expensive structural materials because of the corrosiveness of the product under the reaction conditions.

Carbonylation of olefins can be carried out using a noble metal catalyst at a pressure of about 100 bar. Accordingly, EP-A 495 547 teaches the use of a catalyst comprising a palladium source and a bidentate phosphine ligand. However, such catalysts are frequently inactivated by precipitation of metallic palladium after a short reaction time, in particular the phosphine ligands used are not stable under the desired reaction conditions.

DE-A 2 263 442 describes the carbonylation of olefins in the presence of phenol derivatives or thiophenol derivatives or fluorinated carboxylic acids, thiocarboxylic acids or sulfonic acids on rhodium or iridium containing catalysts containing no halogens have. However, the catalytic activity is unsatisfactory.

WO 98/37049 further contains additional metals at 30 to 100 bar and 100 to 270 ° C. and further contains halogen-free nickel comprising tertiary or quaternary nitrogen, arsenic or phosphorus compounds or nitrogen containing heterocyclic compounds. Carbonylation of olefins on a containing catalyst system is described. The catalyst system is active even at low water concentrations, making it possible to produce carboxylic acids with a water content of less than 1% even in reactor effluents. Disadvantages are the instability of the quaternary ammonium compounds at the required high temperatures and also the high volatility and toxicity of the nickel tetracarbonyl formed during the reaction, which necessitates high cost purification of the waste gas.

EP-A 759 420 can be used to carry out olefins on a halogen-free catalyst system comprising a rhodium compound and at least one heterocyclic compound at 30 to 200 ° C. and 30 to 200 bar, which can be carried out in a glycol ether solvent. It describes a method of producing carbonyl by carbonylation. However, catalyst systems have low activity at low water concentrations and provide low selectivity carboxylic acids under these conditions.

It is an object of the present invention to provide a process for the carbonylation of olefins which avoids the above mentioned disadvantages and provides carboxylic acids with good selectivity and activity even at low water concentrations.

The inventors have found that the object is that water and olefin and carbon monoxide from

a) rhodium or rhodium compound,

b) at least one nitrogen-containing heterocyclic compound,

c) at least one alkali metal salt or alkaline earth metal salt of aliphatic C ₂ -C ₂₀ -carboxylic acid, and

d) at least one glycol ether of formula (I)

It has finally been found that this is achieved by a new and improved process for preparing carboxylic acids in the presence of a halogen-free catalyst system comprising a mixture of

Wherein R ¹ and R ² are independently C ₁ -C ₂₀ -alkyl or R ³ CO, wherein R ³ is hydrogen or C ₁ -C ₂₀ -alkyl, or R ¹ and R ² together are C _1- Forms a C ₂₀ -alkylene chain, n is 1 to 30;

The process of the invention allows the activity and selectivity to be significantly improved compared to the catalyst system described in EP 759 420, especially at low pressures and low water concentrations of up to 100 bar. In addition, the catalyst system used according to the invention is stable under the reaction conditions. There is no deposition or decomposition of the catalyst components which is particularly disadvantageous for industrial processes. Even at low water concentrations of 0.5 to 2 mol of water per mol of olefin, the catalyst system used in the process of the present invention is active so that the carboxylic acid has a water content of 0 to 5%, preferably less than 1% even in the reactor discharge. Making it possible to prepare the reaction product greatly simplifies the finishing of the reaction product.

This is particularly surprising because US-A 3 917 677 and EP-A 55 875 report the adverse effects of alkali metal salts of aliphatic carboxylic acids such as sodium acetate on halogen-free carbonylation catalysts. Thus, Example 7 of US Pat. No. 3,917,677 describes that the activity of halogen-free rhodium / phosphine catalysts in the alkoxycarbonylation of olefins is greatly reduced in the presence of sodium acetate. Example 9 of EP-A 55 875 reports the loss of all activity of a halogen-free palladium catalyst system in the presence of sodium acetate.

Using the conversion of ethylene to propionic acid, for example, the following scheme represents the process of the present invention.

Suitable starting materials for the process of the invention are aliphatic and cycloaliphatic alkenes having preferably 2 to 20, particularly preferably 2 to 7 carbon atoms. Examples thereof are isomers of ethylene, propylene, iso-butene, 1-butene, 2-butene and pentene and hexene as well as cyclohexene, of which ethylene is preferred.

The above-mentioned starting materials are reacted with water and carbon monoxide (CO), and the carbon monoxide can be used in pure form or diluted with an inert gas such as nitrogen or argon. The molar ratio of the starting compound olefin and water can vary within wide ranges but at least equimolar amounts of water are generally used. However, 0.5 to 2 mol, preferably 0.9 to 1.5 mol of water per mol of the olefin is preferably used to obtain a carboxylic acid having a water content of 0 to 5%, particularly preferably 0 to 1%, in the reactor effluent. use.

In addition, the molar ratio of olefins to carbon monoxide can vary widely from 5: 1 to 1: 5, with a molar ratio of olefins to carbon monoxide (moles of olefins per mol of carbon monoxide) of 0.5: 1 to 1.5: 1 being preferred.

In the process of the invention, the catalyst system containing no halogen is

a) rhodium or rhodium compound,

b) at least one nitrogen-containing heterocyclic compound,

c) at least one alkali metal salt or alkaline earth metal salt of aliphatic C ₂ -C ₂₀ -carboxylic acid, and

d) at least one glycol ether of formula (I)

It contains a mixture of.

<Formula I>

Wherein R ¹ and R ² are independently C ₁ -C ₂₀ -alkyl or R ³ CO, wherein R ³ is hydrogen or C ₁ -C ₂₀ -alkyl, or R ¹ and R ² together are C _1- Forms a C ₂₀ -alkylene chain, n is 1 to 30;

The catalyst system of the present invention preferably contains no nickel and nickel compounds and preferably no phosphine.

To enable the formation of catalytically active rhodium containing components, soluble rhodium compounds such as acetates, propionates, acetylacetonates, oxides, hydroxides or carbonates are advantageously added to the reaction mixture. More suitable rhodium compounds are carbonyl compounds, in particular dicarbonylodium acetylacetonate, bis (dicarbonylodium propionate), bis (dicarbonylodium acetate), Rh ₄ (CO) ₁₂ , Rh ₆ (CO) ₁₆ , salts of anions [Rh ₁₂ (CO) ₃₀ ] ^2- , or metal compounds stabilized by donor ligands or olefins such as nitrogen bases. Depending on the solubility, rhodium is present in dissolved form or in suspension in the reaction mixture. The formation of the active catalyst component a) can be promoted by the introduction of hydrogen into the reaction mixture. In addition, activation of this catalyst component (precarbonylation) can be carried out by reaction with CO and water or with CO and hydrogen at pressures of 50 to 150 ° C. and 50 to 150 bar in separate reaction spaces. In addition, the rhodium or rhodium compounds of the catalyst component a) can be used on organic or inorganic inert supports such as activated carbon, graphite, aluminum oxide, zirconium oxide and silicon oxide. The rhodium content (calculated as metal) of the reaction solution is generally 0.001 to 1% by weight, preferably 0.01 to 0.5% by weight.

Suitable nitrogen-containing heterocyclic compounds b) are pyridine, pyridine, quinoline and isoquinoline containing 1 to 3 C ₁ -C ₃₀ -alkyl, aryl or arylalkyl groups as substituents, pyrimidine, pyridazine, pyrazine, pyrazole , Imidazole, thiazole and oxazole. Preferred are unsubstituted pyridine or pyridine monosubstituted with C ₁ -C ₃₀ -alkyl, aryl or arylalkyl, for example 4-ethylpyridine, 4-tridecylpyridine, 4-tert-butylpyridine, 4- ( Phenylpropyl) pyridine, 4-phenylpyridine or 4-benzylpyridine and 4,4'-trimethylenedipyridine. The amount of nitrogen-containing heterocyclic compound present in the reaction solution is generally 1 to 50% by weight, preferably 5 to 30% by weight.

Preferred as alkali metal salts or alkaline earth metal salts c) are lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium or barium, particularly preferably sodium or potassium, aliphatic C ₂ -C ₂₀ -carboxylic acid, preferably Preferably a salt of an aliphatic C ₂ -C ₁₀ -carboxylic acid such as acetic acid, propionic acid or butyric acid. Very particular preference is given to using alkali metal or alkaline earth salts of the carboxylic acids to be prepared. The preparation of propionic acid is therefore preferably carried out using propionate, particularly preferably sodium or potassium propionate. The amount of alkali metal or alkaline earth metal salt of C ₂ -C ₂₀ -carboxylic acid present in the reaction solution is generally 1 to 50% by weight, preferably 5 to 30% by weight. It is also possible to prepare alkali metal salts or alkaline earth metal salts c) in situ by reaction with the corresponding carboxylic acids from suitable precursors, for example alkali metal or alkaline earth metal hydroxides, hydrocarbons, carbonates or oxides.

The further catalyst component d) used is at least one glycol ether of the formula (I).

<Formula I>

Wherein R ¹ and R ² are independently C ₁ -C ₂₀ -alkyl or R ³ CO, wherein R ³ is hydrogen or C ₁ -C ₂₀ -alkyl, or R ¹ and R ² together are C ₁ -C Forms a ₂₀ -alkylene chain, n is 1 to 30; R ¹ and R ² are independently C ₁ -C ₁₀ -alkyl, in particular ethyl, propyl, pentyl or butyl and n is 2, 3 or 4, for example diethylene glycol diethyl ether, diethylene glycol dimethyl ether , Diethylene glycol dibutyl ether and triethylene glycol diethyl ether are preferred. The amount of glycol ether of formula I present in the reaction solution is generally 1 to 70% by weight, preferably 5 to 50% by weight.

The molar ratio of rhodium (calculated as metal) present in the second catalyst component b) to the first component a) of the catalyst system is 10: 1 to 10,000: 1, preferably 50: 1 to 1500: 1. The molar ratio of the third catalyst component c), ie, the alkali or alkaline earth metal salt of C _x -C _y -carboxylic acid to rhodium (calculated as metal), is generally from 10: 1 to 10,000: 1, preferably 50 : 1 to 1500: 1. The molar ratio of catalyst component d) of the catalyst system to rhodium (calculated as a metal) present in the first component a) is 20: 1 to 10,000: 1, preferably 100: 1 to 3000: 1.

Preferred solvents for use in the process of the invention are the starting materials and products and liquid catalyst components which are liquid under the reaction conditions. However, additional solvents may be used. Depending on the composition, the reaction mixture may form a single phase or form two phases. The reaction is generally carried out at a pressure of 30 to 150 ° C, preferably 90 to 120 ° C and 30 to 150 bar, preferably 40 to 100 bar.

The starting compounds olefins, water and catalyst system can be mixed in the reactor prior to the reaction and, if desired, in a solvent. They can then be heated to the reaction temperature and the reaction pressure is set by injection of carbon monoxide or by injection of a mixture of this olefin and carbon monoxide when short chain olefins are used.

The reaction is generally completed after 0.5 to 3 hours. The reaction can be carried out continuously or batchwise in a reactor such as a tank, bubble column, tube reactor or loop reactor.

In order to isolate the process product, the reactor effluent is reduced in a preferred embodiment. The liquid phase of the reactor effluent, including the process product together with the soluble or suspended catalyst, is finished by distillation to isolate the process product and, if appropriate, by subsequent fine distillation finishing. The catalyst-containing distillation column bottoms are returned to the reaction section. Likewise, any catalyst components separated before distillation and also volatile catalyst components separated as low boilers or as side streams during distillation can be returned after appropriate finishing operations.

The process of the present invention allows the production of process products with high selectivity and high space time yields at low water concentrations, low temperatures and moderate pressures while avoiding volatile toxic transition metal compounds as catalyst components. There is no deposition or decomposition of catalyst components, which is particularly disadvantageous for industrial process performance. The process of the present invention can even produce carboxylic acids with a water content of <1% in the reactor effluent and thus obtain significant cost savings in manufacturing and finishing operations.

<Examples 1 to 6>

Batch Experiments on Preparation of Propionic Acid

A 270 ml autoclave provided with a magnetic stir bar was charged with the propionic acid, water and novel catalyst system in the amounts shown in Table 1 below. Subsequently, the initial pressure set forth in Table 1 was set and a gas mixture of 50% by volume CO and 50% by volume ethylene was used unless otherwise indicated in Table 1 below, and the reaction mixture was heated to the temperature described in Table 1 below. . After the reaction temperature was reached, the reaction pressure specified in Table 1 below was set by the CO / ethylene gas mixture and maintained by injecting additional amounts of the CO / ethylene gas mixture. After 1 hour, the autoclave was cooled to room temperature and vented and the reaction product was analyzed by gas chromatography.

The experimental results of Examples 1 to 6 according to the present invention are summarized in Table 1 below. The space time yield (STY _PA ) was calculated by dividing the amount of propionic acid produced by the volume of the reaction solution used (100 ml). Propionic acid selectivity (S _PA ) was based on ethylene as starting compound. The conversion of water is shown as C _{H 2 O} in Table 1 below. Catalyst activity was recorded as conversion water (TOF). The rhodium compound (catalyst component a) used was, in all examples, dicarbonylodium acetylacetonate (Rh (acac) (CO) ₂ ). In the table below, diglyme is diethylene glycol dimethyl ether, PA is propionic acid and DEGBDE is diethylene glycol di-n-butyl ether. The catalyst component c) used in Table 1 below is potassium propionate, abbreviated as KO ₂ CEt.

<Comparative Examples A to E>

Comparative experiments A to E were performed as described above for Examples 1 to 6, but catalyst components c) and d) were not used in Experiments A and B. Experiment C was carried out without catalyst component d) and experiments D and E were carried out without catalyst component c). The results of the comparative experiments are summarized in Table 1 below. Comparative experiments show that the space time yield and selectivity obtained in the absence of one or both of the catalyst components c) and d) are lower than those achieved in Examples 1 to 6 according to the invention.

number PA [g] H ₂ O [g] Pyridine [g] Rh [mmol] Catalyst c) [mmol] Catalyst d) [g] p [bar] T [℃] STY _PA [g / l / h] S _PA [%] [H ₂ O] _emissions [% m / m] C _H2O [%] TOF mol _PA / (mol _RHh ) A ¹⁾ 80 10 10 0.43 - - 100 100 89 86 6.0 34 280 B ²⁾ 85 5 10 0.43 - - 100 100 51 81 2.4 50 237 C ¹⁾ 77 5 10 0.43 250 EN ₂ CEt - 100 100 <5 Cannot be measured 5.1 <1% Cannot be measured D ²⁾ 45 5 10 0.43 - 50 diglyme 100 100 98 90 1.8 60 472 E ²⁾ 45 5 10 0.43 - 50DEGDBE 100 100 12 55 3 33 60 1 ¹⁾ 47 5 10 0.43 125EN ₂ CEt 34 diglyme 100 100 195 94 <0.1 > 99 994 2 ¹⁾ 55 5 10 0.43 105EN ₂ CEt 28 diglyme 100 100 131 95 0.6 80 640 3 ³⁾ 47 5 10 0.86 125EN ₂ CEt 34 diglyme 55 100 184 92 0.4 91 469 4 ²⁾ 45 5 10 0.43 125EN ₂ CEt 50DEGDBE 100 100 156 93 <0.1 > 99 905 5 ³⁾ 45 5 10 0.43 125EN ₂ CEt 50DEGDBE 55 100 189 96 0.7 82 1055 6 ³⁾ 46 10 10 0.43 125EN ₂ CEt 34 diglyme 55 110 300 95 1.84 77 1660 ¹⁾ Initial pressure 30 bar CO / ethylene gas mixture ²⁾ Initial pressure 9.5 bar CO ³⁾ Initial pressure 4.5 bar CO

Claims (11)

a) rhodium or rhodium compound, b) at least one nitrogen-containing heterocyclic compound, c) at least one alkali metal salt or alkaline earth metal salt of aliphatic C ₂ -C ₂₀ -carboxylic acid, and d) at least one glycol ether of formula (I) A process for the preparation of carboxylic acids from olefins and carbon monoxide in the presence of water, using a catalyst system free of halogen, comprising a mixture of <Formula I> Wherein R ¹ and R ² are independently C ₁ -C ₂₀ -alkyl or R ³ CO, wherein R ³ is hydrogen or C ₁ -C ₂₀ -alkyl, or R ¹ and R ² together are C _1- Forms a C ₂₀ -alkylene chain, n is 1 to 30; The process of claim 1, wherein the components of the catalyst system are present in a molar ratio of a): b): c): d) from 1: 10: 10: 20 to 1: 10,000: 10,000: 10,000. 3. Pyridine, quinoline and isoquinoline, pyrimidine, pyridazine according to claim 1 or 2, wherein the catalyst component b) contains pyridine, a substituent containing 1 to 3 C ₁ -C ₃₀ -alkyl, aryl or arylalkyl groups , Pyrazine, pyrazole, imidazole, thiazole and oxazole. The process for producing carboxylic acid according to claim 1, wherein the catalyst component c) is a sodium or potassium salt of aliphatic C ₂ -C ₂₀ -carboxylic acid. The process according to claim 1 or 2, wherein the catalyst component d) used is of formula I, wherein R ¹ and R ² are the same or different and are each C ₁ -C ₂₀ -alkyl and n is 2, 3 or 4 The manufacturing method of carboxylic acid which is a glycol ether of. 6. The process of claim 1, wherein the reaction solution comprises 0.5 to 2 mol of water per mol of olefin. 7. The process for producing a carboxylic acid according to claim 1, wherein the reaction is carried out at 30 to 150 ° C. and at a pressure of 30 to 150 bar. The process for producing a carboxylic acid according to any one of claims 1 to 7, wherein carbon monoxide and olefins are used in a molar ratio of 5: 1 to 1: 5. The process for producing a carboxylic acid or ester thereof according to any one of claims 1 to 7, wherein the olefin used is ethylene. 10. A catalyst system free of halogen according to claim 1, which is suitable for carrying out the process for the preparation of a carboxylic acid or ester thereof according to claim 1. Use of the catalyst system according to any one of claims 1 to 5 for the production of carboxylic acids from olefins and carbon monoxide in the presence of water.