JPS621960B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for obtaining a Group 8 noble metal solid complex. Specifically, the present invention relates to a method for economically and efficiently obtaining a group 8 noble metal solid complex from an organic compound-containing solution containing a group 8 noble metal complex having a tertiary organophosphorus compound as a ligand. .

Group 8 noble metal-tertiary organophosphorus compound complexes are useful in various reactions such as the hydrogenation of olefins, carbonyl compounds, aromatic compounds, etc. by homogeneous catalytic reactions, and the hydroformylation and hydrocarboxylation of olefins. In particular, rhodium-triarylphosphine complexes are industrially advantageously used as catalysts for the hydroformylation of olefins.

These Group 8 noble metal complexes are chemically extremely stable, so the reaction product and catalyst liquid can be separated by distillation, and the catalyst liquid can be recycled to the reaction zone for reuse, or the reaction product can be recycled. It has the advantage that it can be distilled and separated from the reaction zone by gas stripping, and the reaction can be carried out continuously while the catalyst liquid remains in the reaction zone.

However, various high-boiling by-products are produced in these reactions. Therefore, when these reactions are carried out continuously, high-boiling by-products accumulate in the catalyst liquid, so it is necessary to withdraw a portion of the catalyst liquid from the reaction system either continuously or intermittently. Since the extracted catalyst liquid contains expensive Group 8 noble metals, it is extremely important to efficiently recover this from both economical and environmental standpoints.

Conventionally, methods for separating and recovering Group 8 noble metal complexes from extracted catalyst liquid include an extraction method using a strong acid (Japanese Patent Publication No. 46-43219) and a decomposition method using a peroxide (US Patent No. 3547964, JP-A No. 1983-1989). 63388) etc. are known.

Among these methods, the strong acid extraction method involves adding a strong acid (for example, 60% or more sulfuric acid) to the waste catalyst solution, extracting the rhodium complex with the strong acid, and adding water to the acid solution containing the rhodium complex obtained by phase separation. When the acid is added and diluted, the rhodium complex precipitates, so this precipitate is extracted with a solvent and the rhodium complex is recovered from the acid aqueous solution. This method requires complicated operations such as extraction with a strong acid and then adding water to a strong acid solution containing the resulting rhodium complex.

In addition, in the peroxide decomposition method, the waste catalyst liquid is treated with an acid aqueous solution such as nitric acid and a peroxide, the aqueous phase containing the rhodium salt is separated, and the excess peroxide is decomposed by heating. This method involves treating the aqueous phase with carbon monoxide under pressure in the presence of an organic solvent and a complex forming substance such as triphenylphosphine to obtain a rhodium complex in the organic solvent phase. This method also not only requires a complex operation of peroxide treatment followed by carbon monoxide treatment, but also the peroxide treatment produces dangerous by-products such as organic peroxides. There are concerns.

As a result of intensive study on a method for efficiently recovering Group 8 noble metal complexes in a solution containing an organic compound with simple operations, the present inventors discovered that the above solution was treated with an oxidizing agent in the presence of a polar organic solvent, water, and hydrogen chloride. The present invention was completed based on the discovery that a solid complex of Group 8 noble metal crystallizes when brought into contact with.

That is, an object of the present invention is to provide a method for industrially advantageously separating and obtaining a solid complex of a group 8 noble metal from an organic compound-containing solution containing a tertiary group 8 noble metal complex. A solid complex of a Group 8 noble metal is crystallized by contacting an organic compound solution containing a Group 8 noble metal complex having an organophosphorus compound as a ligand with an oxidizing agent in the presence of a polar organic solvent, water, and hydrogen chloride. Then, the 8th crystallized
This is easily achieved by separating the group noble metal solid complexes from the liquid.

Next, the present invention will be explained in detail.

The present invention is applied to recovery of a Group 8 noble metal complex from an organic compound-containing solution containing a Group 8 noble metal complex having at least one tertiary organophosphorus compound as a ligand. In particular, the present invention is advantageously applied to the case where Group 8 noble metals in a catalyst solution separated from reaction products by distillation or the like in olefin hydroformylation or hydrocarboxylation reactions are recovered as a complex. Group 8 noble metal complexes having a tertiary organophosphorus compound as a ligand are compounds of group 8 noble metals, such as hydrides,
It can be easily prepared from a halide, carboxylate, nitrate, sulfate, etc. and a tertiary organophosphorus compound such as tertiary phosphine or trisubstituted phosphite by a known complex formation method.
In some cases, a group 8 noble metal compound and a tertiary organophosphorus compound may be supplied to the reaction system to form a complex there.

Compounds of Group 8 noble metals used to prepare the complexes include, for example, ruthenium compounds such as ruthenium trichloride, tetraamminehydroxochlororuthenium chloride; rhodium dicarbonyl chloride, rhodium nitrate, rhodium trichloride, rhodium acetate, sulfuric acid. Rhodium compounds such as rhodium: palladium compounds such as hydrogen palladium, palladium chloride, palladium cyanide, palladium iodide, palladium nitrate, palladium acetate, palladium sulfate; osmium compounds such as osmium trichloride and chloroosmic acid; iridium tribromide, Iridium compounds such as iridium tetrabromide, iridium trifluoride, iridium trichloride, and iridium carbonyl; platinum compounds such as platinum acid, platinum iodide, sodium hexachloroplatinate, potassium trichloro(ethylene) diplatinate, etc. It will be done. Examples of tertiary organophosphorus compounds used for complex preparation include trimethylphosphine, tris(aminoamyl)phosphine, tricyclohexylphosphine, triphenylphosphine, and tris(N,N-
dimethylanilyl)phosphine, tri-P-tolylphosphine, tri-m-tolylphosphine, phenyldiisopropylphosphine, phenyldiamylphosphine, ethyldiphenylphosphine,
Tris(N,N-diethylaminomethyl)phosphine, ethylenebis(diphenylphosphine),
Trianylylphosphine, diphenyl (N,N-
dimethylanilyl)phosphine, triphenylanilylethylenediphosphine, tris(3,5-
diaminophenyl) phosphine, tertiary phosphines such as aminoethyltriisopropylhexamethylene diphosphine, trimethylphosphine,
Examples include trisubstituted phosphites such as triphenyl phosphite, tricyclohexyl phosphite, and tetraphenylethylene diphosphite.

Hereinafter, from a catalyst solution for a hydroformylation reaction using a Group 8 noble metal complex formed from a Group 8 noble metal compound and a tertiary organophosphorus compound, especially a rhodium-triarylphosphine complex as a catalyst, The present invention will be explained by taking as an example a case where a noble metal solid complex is separated and obtained. In this case, the hydroformylation reaction converts linear α-olefins such as ethylene, propylene, 1-butene, 1-hexene, and 1-octene, and vinylidene structures such as isobutene in the presence of a rhodium-triarylphosphine complex. Olefins having 2 to 20 carbon atoms, such as olefins with
The reaction is carried out by reacting with oxo gas consisting of carbon monoxide and hydrogen (H ₂ /CO (molar ratio) = 1/3 to 20) in the presence or absence of a reaction solvent. The concentration of the rhodium complex in the reaction medium is usually several mg/ to several hundred mg/ in terms of rhodium atoms,
In addition, triarylphosphine used as a ligand is used in the reaction medium in an excess amount of several times to several thousand times in molar ratio relative to the rhodium complex catalyst in order to increase the stability of the catalyst. . The aldehyde produced by the hydroformylation reaction is separated from the catalyst liquid and recovered by stripping with unreacted gas or distillation. The catalyst liquid is left in the reaction zone or is recycled to the reaction zone and used for the reaction. A portion of the catalyst liquid is continuously or intermittently drawn out of the reaction zone as a waste catalyst liquid in order to avoid accumulation of high-boiling by-products, and a corresponding amount of catalyst and Triarylphosphine is freshly fed to the reaction zone.

The method of the present invention is applied to the waste catalyst liquid extracted from the reaction system. However, if the waste catalyst liquid contains a large amount of reaction solvent other than high-boiling byproducts, the reaction solvent is further removed from the waste catalyst liquid by a known method such as distillation, and the concentration of the complex catalyst in the liquid is reduced. Usually 10mg/or more when converted to rhodium atoms,
Preferably 100 mg/or more, most preferably 500
It is advantageous to apply the method according to the invention after increasing the amount to more than mg/mg/ml.

In the method of the present invention, an organic compound-containing solution containing a Group 8 noble metal complex having at least one tertiary organophosphorus compound as a ligand is mixed with an oxidizing agent in the presence of a polar organic solvent, water, and hydrogen chloride. The solid complex of Group 8 noble metal is crystallized and separated and recovered.

As the polar organic solvent to be present in the organic compound-containing solution, alcohols or a mixture of alcohols and an organic solvent that serves as a poor solvent for the solid complex to crystallize are preferably employed. As for alcohol,
For example, monohydric alcohols or dihydric alcohols having 1 to 12 carbon atoms such as ethyl alcohol, propyl alcohol, t-butyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol are used. These alcohols can be used alone or as a mixture thereof. In addition, as a poor solvent for the solid complex to be crystallized, solvents in which these group 8 noble metal-tertiary organophosphorus compound complexes are poorly soluble, such as ethers having 2 to 12 carbon atoms such as dimethyl ether and diethyl ether, can be used. , n-pentane, n-hexane, n-
Examples include paraffins having 5 to 10 carbon atoms such as heptane. Particularly preferred polar organic solvents are ethyl alcohol and propyl alcohol.
The amount of these polar organic solvents added depends on the amount of water present, but is sufficient to make the treatment solution system a poor solvent system for the solid complex to be crystallized. In the case of the number of alcohols, it is desirable that the alcohol be present in a molar ratio of 1 or more to the Group 8 noble metal. The suitable amount to be added varies depending on the type and amount of the reaction solvent and high-boiling byproduct contained in the organic compound-containing solution. If the amount of polar organic solvent added is too small, the recovery rate of the Group 8 noble metal solid complex will decrease.

The amount of water present in the organic compound-containing solution is preferably 1 or more in molar ratio to the Group 8 noble metal.
10 or more, and may be added either in the form of water itself or in the form of an aqueous solution of hydrogen chloride.

The amount of hydrogen chloride is at least 1, preferably at least 10, in molar ratio to the Group 8 noble metal. Hydrogen chloride may be added as hydrogen chloride, or may be added as an aqueous solution, that is, hydrochloric acid, which also serves as the addition of water.

As the oxidizing agent brought into contact with the organic compound-containing solution, oxygen gas or an oxygen-containing gas such as air is preferably used. The amount of the oxidizing agent is required to be 1 or more in molar ratio to the Group 8 noble metal. When air is used as the oxidizing agent, it is sufficient to maintain the solution system to be treated in an air atmosphere, but it may also be blown into the solution or used under pressure. The conditions for the contact treatment with an oxidizing agent may be relatively mild conditions, and specifically, usually, a mixture of an organic compound-containing solution, a polar organic solvent, water, and hydrogen chloride is brought into contact with an oxidizing agent, The tertiary organophosphorus compound is treated as a ligand by treatment at a temperature of -20 to 200°C for a contact time of several minutes to several days, preferably at 0°C or the boiling point of the solution system for several minutes to several hours. 8th having as
Group noble metal solid complexes can be crystallized. Further, by further lowering the temperature of the treatment solution containing the crystallized Group 8 noble metal solid complex, the amount of the Group 8 noble metal solid complex crystallized can be increased.

The chemical structure of the Group 8 noble metal solid complex that crystallizes is:
It depends on the type of Group 8 noble metal, the type of tertiary organophosphorus compound, the composition of the treatment solution, for example, the presence of a coordination compound other than the tertiary organophosphorus compound. For example, when a catalyst solution for a hydroformylation reaction using a rhodium-triarylphosphine complex as a catalyst is brought into contact with an oxidizing agent in the presence of alcohols, water, and hydrogen chloride, RhClCO
A rhodium complex mainly consisting of (PR ₃ ) ₂ (in the formula, PR ₃ represents triarylphosphine) is crystallized.

The crystallized Group 8 noble metal solid complex can be subjected to solid-liquid separation by a conventional solid-liquid separation method, such as filtration, centrifugation, centrifugation, etc., and the Group 8 noble metal solid complex can be separated and recovered. If desired, HRhCO(PR ₃ ) ₃ (where PR ₃ is It can also be converted into a complex such as triarylphosphine.

As explained in detail above, according to the method of the present invention, a solid complex of a Group 8 noble metal having a tertiary organophosphorus compound as a ligand can be efficiently recovered from an organic compound-containing solution by a simple operation. Therefore, the industrial value of the present invention is extremely large.

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 it exceeds the gist thereof.

Example 1 A waste catalyst solution from the hydroformylation of propylene using a rhodium-triphenylphosphine complex catalyst was concentrated by distillation, and the concentration of the complex was 800 mg/concentration in terms of rhodium atoms, and the concentration of free triphenylphosphine was 100 c.c. of a high-boiling medium solution prepared at 570 mmol/into a four-necked flask with an internal volume of 1000 c.c. equipped with a reflux condenser, a thermometer, and a stirring device, and the temperature was raised to 40°C while stirring. , and 100 c.c. of 5N hydrochloric acid aqueous solution and ethyl alcohol.
Added 400c.c. and 40% under normal pressure air atmosphere.
When treated at ℃, the rhodium complex began to crystallize after about 20 minutes. After 5 hours of treatment, the crystallized product was filtered under pressure, further washed with water and ethyl alcohol, and then vacuum dried at room temperature to obtain a yellow solid complex. The solid complex obtained contains 15% by weight of rhodium, 5% by weight of chlorine, and 9% by weight of phosphorus and also contains nujol.
In the infrared absorption spectrum obtained by the method, Rh−
Absorption of 1980 ^-1 was observed, which appears to be caused by CO binding. From these results, it is estimated that the solid complex obtained mainly has the chemical formula RhClCO[P(C ₆ H ₅ ) ₃ ] ₂ .

The recovery rate of the rhodium complex was 90% in terms of rhodium atoms. In addition, the concentration of triphenylphosphine in the liquid after separation is 50 mmol/, and the concentration of triphenylphosphine before treatment.
Of the 95 mmol, 45 mmol was oxidized to triphenylphosphine oxide.

Example 2 n instead of ethyl alcohol in Example 1
- Treated under the same conditions except that propyl alcohol was used.

As a result, the recovery rate of the rhodium complex was 90%. The concentration of triphenylphosphine in the solution after separation is 60 mmol/, and the concentration of triphenylphosphine in the solution before treatment is 95 mmol/
Of this, 35 mmol was oxidized to triphenylphosphine oxide.

Claims (1)

[Claims] 1. An organic compound-containing solution containing a Group 8 noble metal complex having a tertiary organophosphorus compound as a ligand is mixed with an oxidizing agent in the presence of a polar organic solvent, water, and hydrogen chloride. 1. A method for obtaining a Group 8 noble metal solid complex, which comprises contacting to crystallize a Group 8 noble metal solid complex, and then separating the crystallized Group 8 noble metal solid complex from a liquid. 2. The method for obtaining a Group 8 noble metal solid complex according to claim 1, wherein the organic compound-containing solution is a solution containing a catalyst for a hydroformylation reaction. 3. A method for obtaining a group 8 noble metal solid complex according to claim 1 or 2, characterized in that the group 8 noble metal is rhodium. 4. The method for obtaining a Group 8 noble metal solid complex according to any one of claims 1 to 3, characterized in that the tertiary organophosphorus compound is triarylphosphine. Method. 5. The method for obtaining a Group 8 noble metal solid complex according to claim 4, wherein the tertiary organophosphorus compound is triphenylphosphine. 6. In the method for obtaining a Group 8 noble metal solid complex according to any one of claims 1 to 5, the polar organic solvent is a monohydric alcohol or a dihydric alcohol having 1 to 12 carbon atoms. A method characterized by: 7. A method for obtaining a group 8 noble metal solid complex according to claim 6, characterized in that the polar organic solvent is ethyl alcohol. 8. A method for obtaining a Group 8 noble metal solid complex according to claim 6, characterized in that the polar organic solvent is propyl alcohol.