JPH0549346B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to the oxidative coupling of o-phthalic acid diesters in the presence of a catalyst comprising a divalent palladium salt and a copper salt and a basic bidentate ligand; This invention relates to an improvement in the method of recovering palladium-copper catalyst from the reaction solution. [Background of the Invention] Catalysts containing divalent palladium salts are useful as catalysts for organic synthesis, such as when oxidatively coupling o-phthalic acid diesters. ) are collected and reused. For example, it is synthesized by oxidative coupling of dimethyl o-phthalate using a catalyst containing tetramethyl biphenyltetracarboxylate, a divalent palladium salt, a copper salt, and a basic bidentate ligand. Tetramethyl biphenyltetracarboxylate is an intermediate product when synthesizing biphenyltetracarboxylic dianhydride, and biphenyltetracarboxylic dianhydride is important as one of the raw material monomers for aromatic polyimide. . Conventionally, catalysts consisting only of divalent palladium salts used in the above-mentioned synthesis reactions have been developed, for example, by
It was collected by filtration from the reaction solution by the method described in No. 53-20009. The recovery method described in Japanese Patent Publication No. 53-20009 involves reducing the divalent palladium salt or its organic complex uniformly dispersed in the reaction solution to zero valence after the completion of the above-mentioned reaction to form palladium black, which is precipitated. The precipitate is filtered out. However, the palladium black precipitate reduced by the recovery method described in Japanese Patent Publication No. 53-20009 has a very fine particle size of 0.1 to 5 μm, and is uniformly dispersed in the reaction solution to form a slurry.
For this reason, there was a problem in that it did not easily settle even if it was allowed to stand for a long time, and it was very difficult to separate it from the reaction solution. When the fine particles of palladium black as described above are entrained in the reaction solution, when the tetramethyl biphenyltetracarboxylate, which is the product of the oxidative coupling reaction, is separated and purified, the product is decomposed and Not only does this have adverse effects such as deterioration, but it also becomes impossible to recover fine palladium black in a reusable state in the separation and purification steps described above. In addition, as mentioned above, in recent years, in order to increase the reaction yield, the oxidative coupling reaction of o-phthalic acid esters has been carried out using not only palladium salts but also copper salts and basic compounds such as 1,10-phenanthroline. There is a tendency to use a catalyst system in which bidentate ligands are present, and it is a big problem how to effectively recover the palladium and copper used as a catalyst in such a complex system. Therefore, it is desired to develop a method for efficiently separating and recovering the catalytic metal component consisting of palladium black and metallic copper from the reaction solution after the completion of the oxidative coupling reaction. [Object of the invention] The present invention is directed to reducing palladium and metal from a reaction solution obtained by subjecting an o-phthalic acid diester to an oxidative coupling reaction in the presence of a catalyst containing a divalent palladium salt and a copper salt. It is an object of the present invention to provide an improved method for recovering a catalytic metal component consisting of copper. [Summary of the Invention] The present invention provides 10 ~500 mesh of carrier was introduced and subjected to reduction treatment with hydrogen gas in an atmosphere of hydrogen pressure of 5 to 60 atmospheres, thereby depositing metallic palladium and metallic copper on the surface of the carrier and supporting it on the carrier. The present invention provides a method for recovering palladium/copper catalyst, which is characterized by recovering palladium and copper in a state in which palladium and copper are recovered. [Detailed description of the invention] In the present invention, the reaction solution refers to a reaction solution obtained by subjecting an o-phthalic acid diester to an oxidative coupling reaction in the presence of a catalyst containing a divalent palladium salt, a copper salt, and a basic bidentate ligand. The subsequent reaction solution may have any composition, but for example,
Suitable examples include the oxidative coupling reaction solution used in producing biphenyltetracarboxylic acid tetraester by the method described in Japanese Patent No. 33379. The o-phthalic acid diester, which is a raw material for the above reaction, is a diester of o-phthalic acid and a compound having a hydroxyl group at the end (e.g., lower aliphatic alcohol, aromatic alcohol, etc.). , o-phthalic acid di-lower alkyl esters such as o-dimethyl phthalate, o-diethyl phthalate, o-dipropyl phthalate, and dibutyl o-phthalate can be preferably mentioned. The divalent palladium salt constituting the catalyst is preferably a palladium salt of an aliphatic carboxylic acid or an inorganic acid. Palladium salts of aliphatic carboxylic acids include palladium formate, palladium acetate, palladium propionate, palladium butyrate,
Examples include palladium valerate,
Palladium acetate is preferred. Examples of palladium salts of inorganic acids include palladium chloride, palladium sulfate, palladium sulfite, palladium nitrate, palladium nitrite, palladium phosphate, and the like, with palladium nitrate being preferred. The above palladium salt may form an organic complex (chelate salt) with a basic bidentate ligand described below. The copper salt constituting the catalyst is preferably a copper salt of an organic or inorganic acid, or a copper chelate salt of β-diketones. Examples of copper salts of organic acids include copper salts of aliphatic mono- or dicarboxylic acids having 1 to 5 carbon atoms, such as copper formate, copper acetate, copper propionate, copper butyrate, copper valerate, copper oxalate, etc. copper acetate is preferred. Examples of copper salts of inorganic acids include copper sulfate, copper sulfite, copper nitrate, copper nitrite, and copper phosphate, with copper nitrate being preferred. Examples of copper chelate salts of β-diketones include copper chelate salts such as acetylacetone, benzoylacetone, and trifluoroacetone. Examples of the basic bidentate ligand constituting the above catalyst include 1,10-phenanthroline and 2,2'-bipyridine. The oxidative coupling reaction of the o-phthalic acid diester is carried out by heating the o-phthalic acid diester in the presence of the above catalyst and air in an oxidative coupling reaction tank. Although a solvent is not particularly required in the above oxidative coupling reaction, a nonpolar solvent may be used if desired. As the above-mentioned nonpolar solvent, organic acid esters such as ethylene glycol diacetate and methyl adipate; ketone compounds such as n-butyl methyl ketone, ethyl methyl ketone, and isopropylethyl ketone can be used. After the above-mentioned oxidation coupling reaction is completed, the reaction solution is sent to a catalyst recovery reactor. In the reaction solution, a catalyst consisting of the above-mentioned components, biphenyltetracarboxylic acid diester which is a product of the oxidative coupling reaction, unreacted o-phthalic acid diester, by-products of the oxidative coupling reaction, etc. are uniformly dispersed. are doing. Next, a carrier is added to the reaction solution to reduce the catalyst components palladium and copper. The carrier that can be used in the present invention is not particularly limited as long as it can be used for ordinary catalysts, but silica, activated carbon, or alumina is preferable. The particle size of the above carrier is 10 to 500 mesh (Tyler sieve), preferably 50 to 300 mesh. The amount of the carrier to be used is 1 to 1000 g, preferably 2 to 200 g, per 1 g of palladium and copper, which are catalyst components contained in the reaction solution. Palladium and copper can be reduced by conventionally known methods, for example, by pressurizing the reaction solution with a reducing gas such as hydrogen or by adding a reducing agent. It is preferable to pressurize with hydrogen. The amount of hydrogen used in the reduction treatment was as follows: reaction solution 1 containing 1000 ppm of palladium and copper as catalyst components.
per hit, 2 to 50 under standard conditions, preferably 5 to 25
The pressure of hydrogen in the reaction system is from normal pressure to 300 atmospheres,
Preferably it is 5 to 60 atmospheres. Pressurize the reaction solution with hydrogen within the above range, and
A reduction treatment is performed by stirring for 10 hours, preferably 1 to 5 hours, and metallic palladium and metallic copper are deposited on the surface of the above-mentioned carrier. Since the metallic palladium and metallic copper deposited by the above-mentioned reduction treatment are supported by the carrier,
It does not form a slurry with the reaction solution, and settles just by standing for a short time, and is easily filtered from the reaction solution.
It can be recovered. The recovered palladium supported on the carrier and the copper supported on the carrier can be separated from the carrier as an aqueous solution of palladium nitrate and copper nitrate by dissolving it in nitric acid. −By the method described in Publication No. 20009,
It can be easily regenerated as a catalyst for the above-mentioned oxidative coupling reaction. [Effects of the Invention] According to the method of the present invention, the catalyst components palladium and copper can be efficiently and easily recovered from the oxidative coupling reaction solution of o-phthalic acid diester, and the loss of palladium that accompanies the recovery process can be avoided. can be reduced. Next, examples of the present invention will be shown. [Example 1] Reaction of oxidative coupling of dimethyl o-phthalate using a catalyst consisting of palladium acetate, 1,10-phenanthroline, and copper acetate according to the method described in Japanese Patent Publication No. 60-33379. Palladium and copper were reduced in the presence of a carrier in the solution. The above reaction solution contained palladium 670ppm,
It also contained 123ppm of copper. The concentrations of palladium and copper were measured by atomic absorption spectrometry. Take 300ml of the above reaction solution into a 500ml autoclave made of SUS316, and add silica powder (200 mesh).
Add 1g, pressurize to 15 atmospheres with hydrogen, and heat at 220℃.
Reduction treatment was performed for 3 hours while stirring at 300 rpm.
After the reduction treatment, take out the reaction solution and filter it to remove the precipitate.
1.235g was obtained. The concentration of palladium in the filtrate was 7 ppm, which was 1.0% relative to the palladium in the initial reaction solution. The concentration of copper was 0 ppm, 0% of the copper in the initial reaction solution. Table 1 shows the recovery rate of palladium. [Comparative Example 1] Example 1 except that silica powder was not used.
It was treated in the same manner as above to obtain 0.229 g of precipitate. The concentration of palladium in the filtrate was 25 ppm, which was 3.7% relative to the palladium in the initial reaction solution. The concentration of copper was 0 ppm, 0% of the copper in the initial reaction solution. Table 1 shows the recovery rate of palladium. [Example 2] Activated carbon powder (300 mesh) instead of silica powder
2.236 g of precipitate was obtained by processing in the same manner as in Example 1, except that 2 g was used. The concentration of palladium in the filtrate was 4 ppm, which was 0.6% relative to the palladium in the initial reaction solution. The concentration of copper was 0 ppm, 0% relative to the copper in the initial reaction solution. The recovery rate of palladium is shown in Table 1. [Example 3] 2.236 g of precipitate was obtained in the same manner as in Example 1, except that 2 g of alumina powder (80 mesh) was used instead of silica powder. The concentration of palladium in the filtrate was 11 ppm, 1.6% relative to the palladium in the initial reaction solution. The concentration of copper was 0 ppm, 0% relative to the copper in the initial reaction solution. The recovery rate of palladium is shown in Table 1. It should be noted that all of the copper was adsorbed onto the carrier as described above, and the recovery rate was 100%. 【table】

Claims (1)

[Claims] 1. A reaction solution obtained by subjecting an o-phthalic acid diester to an oxidative coupling reaction in the presence of a catalyst containing a divalent palladium salt, a copper salt, and a basic bidentate ligand.
Introduce a carrier of 10 to 500 mesh, and increase the hydrogen pressure to 5 to 500.
Metallic palladium and metallic copper are deposited on the surface of the carrier by reduction treatment with hydrogen gas in an atmosphere of 60 atmospheres, and the palladium and copper are recovered while supported by the carrier. A method for recovering palladium and copper catalysts. 2. The method for recovering palladium/copper catalyst according to claim 1, wherein the carrier is silica, activated carbon, or alumina.