JP2004026998A - Method for catalyst recovery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for catalyst recovery, with which a used platinum family element-containing catalyst is efficiently separated/recovered from a reaction mixture in the production of a hydride widely carried out in various fields of the chemical industry, especially aftertreatment of a hydrogenation reaction using a supported catalyst obtained by supporting the platinum family element-containing catalyst on a carrier. <P>SOLUTION: The method for catalyst recovery comprises subjecting the platinum family element-containing catalyst, which is fed as the catalyst supported on the carrier to the hydrogenation reaction, is eliminated from the carrier during the hydrogenation reaction and is present in the reaction mixture, to complexing treatment by adding a complexing agent to the reaction mixture so as to resupport the catalyst on the carrier, separating and recovering the catalyst from the reaction mixture. The method for recovering the catalyst is especially preferably applied to the production of a hydrogenated conjugated diene-based polymer so that the polymer is industrially advantageously produced. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for recovering a catalyst containing a platinum group element contained in a hydrogenation reaction mixture and a method for producing a hydrogenated conjugated diene-based polymer.
[0002]
[Prior art]
In the chemical industry that manufactures pharmaceuticals, agrochemicals, petrochemicals, and polymers, a hydrogenation reaction that hydrogenates carbon-carbon unsaturated bonds or carbon-nitrogen unsaturated bonds contained in various compounds and converts them into the corresponding saturated bonds is performed. Widely used.
[0003]
For example, in the field of polymers, a method for selectively or partially hydrogenating a carbon-carbon double bond of a conjugated diene-based polymer is known as a useful means for modifying the polymer, and hydrogenated acrylonitrile-butadiene is known. Hydrogenated conjugated diene-based polymers such as copolymers are produced on an industrial scale.
[0004]
As a typical process for producing such a hydrogenated conjugated diene-based polymer, (1) a step of emulsion-polymerizing a monomer containing a conjugated diene and coagulating and drying the obtained latex to prepare a raw material polymer (2) a step of dissolving the raw material polymer in an organic solvent (hydrogenation reaction solvent), and hydrogenating using a supported catalyst in which a platinum group element-containing catalyst is supported on a carrier insoluble in the organic solvent; 3) a step of separating the carrier supporting the catalyst from the hydrogenation reaction mixture and recovering the target hydrogenated polymer from an organic solvent.
[0005]
The supported catalyst used in the above process is a catalyst in which a platinum group element-containing catalyst is supported on a carrier insoluble in an organic solvent to be used for the purpose of recovering an expensive platinum group element catalyst after the hydrogenation reaction. However, in spite of the fact that the catalyst containing the platinum group element was added in the form of being supported on the carrier, a considerable amount of the catalyst containing the platinum group element was desorbed from the carrier in the reaction mixture after the hydrogenation reaction. It is present in solution, especially near the polymer. Therefore, it is not possible to recover a considerable amount of the platinum group element-containing catalyst only by separating the carrier supporting the catalyst, and after separating and recovering the carrier supporting the catalyst, a large amount of adsorbent is added to the carrier to separate the catalyst. At present, the operation of recovering the remaining catalyst is performed.
[0006]
Also, a process of directly hydrogenating a conjugated diene-based polymer in a latex state obtained by emulsion polymerization without going through a process such as latex coagulation → redissolution has been studied (for example, US Pat. No. 3,898). , 208, JP-A-2-178305, etc.). In this case, the same problem as described above occurs when a supported catalyst is used. When a supported catalyst is used in a hydrogenation reaction in a latex state containing an aqueous medium, the catalytic activity is not sufficiently satisfactory, and a large amount of a platinum group element-containing catalyst is required.
[0007]
Thus, after the hydrogenation reaction, after separating and recovering the supported catalyst, in order to recover the platinum group element-containing catalyst remaining in the polymer solution or the latex by desorbing from the carrier, a further large amount is used. Performing a recovery operation by adding an adsorbent is not preferable in terms of equipment and processing cost, and improvement has been desired.
[0008]
[Problems to be solved by the invention]
In view of the above circumstances, an object of the present invention is to produce a hydride widely used in various fields of the chemical industry, particularly, in the post-treatment stage of the hydrogenation reaction, a platinum group element used in the form of a supported catalyst. It is an object of the present invention to provide a method for efficiently separating and recovering a catalyst from a reaction mixture.
[0009]
Another object of the present invention is to produce a hydrogenated conjugated diene-based polymer by efficiently converting the platinum group element-containing catalyst used in the hydrogenation reaction of the raw material polymer from a reaction mixture containing an organic solvent or an aqueous medium. An object of the present invention is to provide a process for producing a hydrogenated conjugated diene-based polymer which can be separated and recovered well and is industrially advantageous.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventors have proposed a reaction system for producing a hydrogenated conjugated diene-based polymer by using a platinum group element-containing catalyst supported on a carrier in the form of an organic solvent solution. With a focus on the post-treatment method after the completion of the reaction, the present inventors have conducted intensive studies. As a result, they have found that when a complexing agent is added to the reaction mixture to perform a complexing treatment, the platinum group element-containing catalyst that has been desorbed from the support is re-supported on the support and the platinum group element-containing catalyst can be efficiently recovered.
[0011]
In addition, the improvement in the post-treatment method of the hydrogenation reaction as described above is applicable not only to (1) production of a hydrogenated polymer but also to hydrogenation reactions in various fields; Since the used platinum group element-containing catalyst can be easily recovered and reused, even if a large amount of catalyst is used, there is no problem in economy, and the production of various hydrides, especially the production of hydrogenated conjugated diene-based polymers, is industrial. (3) the amount of residual catalyst in the obtained hydride is small, so that there is little adverse effect on the quality of products containing the hydride; The present invention has been completed.
[0012]
Thus, according to the present invention, a complexing agent is added to a reaction mixture of a hydrogenation reaction performed in the presence of a platinum group element-containing catalyst supported on a carrier, and a complexing agent is contained in the reaction mixture. A catalyst recovery method is provided, which comprises complexing the desorbed platinum group element-containing catalyst, re-supporting the resulting complex on a carrier, and recovering the carrier from the reaction mixture. In the catalyst recovery method of the present invention, the reaction mixture is preferably oxidized before adding the complexing agent, and the platinum group element is preferably palladium.
[0013]
Also, according to the present invention, a hydrogenation reaction step (A) of hydrogenating a conjugated diene polymer in the presence of a platinum group element-containing catalyst supported on a support; a platinum group element-containing catalyst desorbed from the support Complexation step (B) in which a complex is added to the reaction mixture by adding a complexing agent to the reaction mixture; a catalyst in which a complex of a platinum group element-containing catalyst is re-supported on the carrier, and the carrier is recovered from the reaction mixture A method for producing a hydrogenated conjugated diene-based polymer comprising a recovery step (C);
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the catalyst recovery method and the method for producing a hydrogenated conjugated diene-based polymer of the present invention will be described in detail.
[0015]
The catalyst recovery method of the present invention, the pharmaceutical, agricultural chemicals, industrial chemicals, petroleum, petrochemicals, polymer products, oils and fats products, edible oils, lubricants, in the field of manufacturing such as fragrance, supported platinum group element containing catalyst on a carrier The present invention can be widely applied to the case where a hydrogenation reaction is carried out in a form, and the catalyst used in the reaction can be efficiently recovered from the reaction mixture.
[0016]
The hydrogenation reaction mixture to which the present method can be applied is not particularly limited as long as it is a reaction mixture obtained by performing a hydrogenation reaction in the presence of a platinum group element-containing catalyst supported on a carrier. Such hydrogenation reactions include, for example, hydrogenation of acetylene to ethylene, hydrogenation of 3-hexyn-1-ol to cis-3-hexen-1-ol, and the like. Hydrogenation reaction to carbon double bond; hydrogenation of gasoline (improvement of gasoline quality), production of isooctane from diisobutylene, production of saturated glyceride from unsaturated glyceride, hydrogenation of conjugated diene polymer to conjugated diene polymer Reaction of a carbon-carbon double bond to a saturated bond typified by the production of phenol; hydrogenation reaction of a carbonyl group for producing a corresponding alcohol from cyclopentanone or cyclohexanone; nitrile group or azomethine group (Schiff base) A hydrogenation reaction of converting to an amino group.
[0017]
The catalyst recovery method of the present invention performs the above various hydrogenation reactions in the presence of a platinum group element-containing catalyst supported on a carrier, adds a complexing agent to the obtained reaction mixture, The catalyst is characterized in that the contained platinum group element-containing catalyst desorbed from the carrier is complexed, the resulting complex is re-supported on the carrier, and the carrier is recovered from the reaction mixture.
In the hydrogenation reaction, a part of the platinum group element-containing catalyst supported on the carrier is detached from the carrier and is present in the reaction mixture. When a complexing agent is added to the reaction mixture, a complex of the platinum group element-containing catalyst desorbed from the carrier is generated. Since the complex is easily supported on the carrier again, the complex is re-supported on the carrier supporting the platinum group element-containing catalyst which has not been desorbed.
The carrier on which the complex is re-supported can be easily recovered from the reaction mixture.Therefore, the complex of the platinum group element catalyst, the complex remaining on the carrier without being desorbed, and the catalyst from the reaction mixture are also collected. It can be recovered together with the carrier.
[0018]
The catalyst count method of the present invention can be particularly preferably applied to a method for producing a hydrogenated conjugated diene-based polymer among the various hydrogenation reactions described above. The hydrogenated conjugated diene-based polymer to which the catalyst recovery method of the present invention can be preferably applied is a conjugated diene monomer typified by butadiene or isoprene, and a monomer copolymerizable therewith. It is a polymer obtained by hydrogenating a carbon-carbon double bond of the obtained polymer. Examples of the monomer copolymerizable with the conjugated diene monomer include α, β-ethylenically unsaturated monomers such as acrylonitrile and acrylate.
[0019]
Hereinafter, specific embodiments of the method for producing a hydrogenated conjugated diene-based polymer to which the catalyst recovery method of the present invention is applied will be described, in which a complexing method, a re-supporting method, and a recovery method of the catalyst recovery method of the present invention are described. Will be described in detail.
[0020]
The method for producing a hydrogenated conjugated diene polymer to which the catalyst recovery method of the present invention is applied (the second invention) is a method for producing a hydrogenated conjugated diene polymer in the presence of a platinum group element-containing catalyst supported on a carrier. Hydrogenation reaction step (A); complexing treatment step (B) of complexing the platinum group element-containing catalyst desorbed from the carrier by adding a complexing agent to the reaction mixture (B); platinum group element-containing catalyst A catalyst recovery step (C) of re-supporting the complex on the carrier and recovering the carrier from the reaction mixture.
[0021]
The hydrogenation reaction step (A), the complexation treatment step (B), and the catalyst recovery step (C) are usually performed in this order, but the formation of the complex in the step (B) and the step (B) The reloading of the complex on the carrier in the step C) means that the generation → reloading may occur in a short time. Other processing steps can be added between the steps as desired. Further, the catalyst recovered in the step (C) can be subjected to purification or regeneration treatment as required, and then can be supplied to the step (A) again.
[0022]
The hydrogenation in the hydrogenation reaction step (A) means that at least a part of the carbon-carbon double bond contained in the conjugated diene polymer is hydrogenated to be converted into a saturated bond. The conjugated diene-based polymer to which this step (A) is applied is obtained by adding at least one kind of conjugated diene monomer or at least one kind of monomer copolymerizable with the conjugated diene monomer. It is produced by a conventionally known emulsion polymerization method or solution polymerization method, preferably by an emulsion polymerization method.
[0023]
The conjugated diene monomer is not particularly limited as long as it is a polymerizable monomer having a conjugated diene structure. For example, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,2 Examples include 3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, and 1,3-pentadiene. Among these, 1,3-butadiene and 2-methyl-1,3-butadiene are preferred, and 1,3-butadiene is more preferred.
[0024]
Examples of monomers copolymerizable with the conjugated diene monomer include α, β-ethylenically unsaturated nitrile monomers such as acrylonitrile, methacrylonitrile, and crotonitrile; acrylic acid, methacrylic acid, crotonic acid Α, β-ethylenically unsaturated carboxylic acids, such as, fumaric acid, maleic acid, and itaconic acid; α, β-ethylenic acids, such as methyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, trifluoroethyl acrylate, and methyl methacrylate Unsaturated carboxylic acid esters; α, β-ethylenically unsaturated carboxylic acid amides such as acrylamide and methacrylamide; vinyl aromatic compounds such as styrene, α-methylstyrene, p-methylstyrene and divinylbenzene; vinyl acetate and vinyl propionate Vinyl esthetic ; Vinylether compounds such as fluoroethyl vinyl ether; and the like.
[0025]
Among these monomers copolymerizable with the conjugated diene monomer, monomers having an electron-withdrawing functional group are preferable from the viewpoint that the hydrogenation reaction in step (A) easily proceeds, and α, β -Ethylenically unsaturated nitrile monomers, especially acrylonitrile, are preferably used.
[0026]
Specific examples of the conjugated diene polymer applied to the hydrogenation in the step (A) include a butadiene polymer, an isoprene polymer, a butadiene-styrene copolymer, an acrylonitrile-butadiene copolymer, and an acrylonitrile-isoprene copolymer. , Acrylonitrile-butadiene-isoprene copolymer, methacrylonitrile-butadiene copolymer, methacrylonitrile-isoprene copolymer, methacrylonitrile-butadiene-isoprene copolymer, acrylonitrile-methacrylonitrile-butadiene copolymer, acrylonitrile- Examples thereof include a methyl acrylate copolymer and an acrylonitrile-butadiene-acrylic acid copolymer.
[0027]
Among the conjugated diene polymers, from the viewpoint of practicality and versatility as a raw material for producing a hydrogenated copolymer, an acrylonitrile-butadiene copolymer and a methacrylonitrile-butadiene copolymer are preferable, and a butadiene-acrylonitrile copolymer is preferable. Polymers are more preferred.
[0028]
The monomer composition ratio in the conjugated diene polymer is not particularly limited, but is 5 to 100% by weight of a conjugated diene monomer and 95 to 0% by weight of a monomer copolymerizable therewith, and is preferably a conjugated diene monomer. 10 to 90% by weight of a monomer and 90 to 10% by weight of a monomer copolymerizable therewith. The weight average molecular weight (gel permeation chromatography, standard polystyrene conversion) is not particularly limited, but is usually 5,000 to 500,000.
[0029]
An emulsion polymerization method suitable as a method for preparing a conjugated diene polymer (raw material) is generally carried out in an aqueous medium using a radical polymerization initiator, and any known polymerization initiator or molecular weight regulator may be used. Just fine. The polymerization reaction may be any of a batch system, a semi-batch system, and a continuous system, and the polymerization temperature and pressure are not particularly limited. The emulsifier to be used is not particularly limited, and an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant and the like can be used, and an anionic surfactant is preferable. These emulsifiers may be used alone or in combination of two or more. The amount used is not particularly limited.
[0030]
The solid content concentration of the conjugated diene polymer latex obtained by emulsion polymerization is not particularly limited, but is usually 2 to 70% by weight, preferably 5 to 60% by weight. The solid content concentration can be appropriately adjusted by a known method such as a blending method, a dilution method, and a concentration method.
[0031]
When the hydrogenation reaction in the step (A) is performed in a latex state (hereinafter, also referred to as “latex-based hydrogenation”), the solid content of the latex is adjusted to a range of 10 to 50% by weight from the viewpoint of reaction efficiency. Is more preferable.
[0032]
In the hydrogenation reaction of the step (A), conventionally, from the viewpoint of catalytic activity and the like, a conjugated diene polymer rubber obtained by coagulating and drying a latex obtained by emulsion polymerization is mainly dissolved in an appropriate organic solvent. It has been performed in the state of a polymer solution (hereinafter, also referred to as “solution-based hydrogenation”).
[0033]
In this case, the coagulation and drying of the latex may be performed by a known method, but by providing a treatment step of bringing the crumb obtained by coagulation into contact with a basic aqueous solution, the obtained conjugated diene-based polymer rubber can be treated with tetrahydrofuran ( It is preferable that the pH of the polymer solution measured by dissolving in THF) is modified so as to exceed 7. The pH of the polymer solution measured in THF is preferably in the range of 7.2 to 12, more preferably 7.5 to 11.5, and most preferably 8 to 11. By the contact treatment between the crumb and the basic aqueous solution, solution-based hydrogenation can be promptly advanced.
[0034]
The solution concentration of the conjugated diene polymer in the solution hydrogenation is 1 to 70% by weight, preferably 2 to 40% by weight. Examples of the organic solvent used for the solution hydrogenation include aliphatic hydrocarbons such as n-hexane, cyclohexane, and n-heptane; aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; acetone, methyl ethyl ketone, and diethyl. Ketones such as ketone, methyl isopropyl ketone, 2-pentanone, 3-pentanone, cyclopentanone and cyclohexanone; ethers such as diethyl ether, tetrahydrofuran, dioxane and anisole; esters such as ethyl acetate; Among these organic solvents, ketones are preferably used.
[0035]
The catalyst used for the hydrogenation reaction in the step (A) is a hydrogenation catalyst containing a platinum group element (ruthenium, rhodium, palladium, osmium, iridium or platinum). As the hydrogenation catalyst, a palladium compound and a rhodium compound are preferable from the viewpoint of catalytic activity and availability, and a palladium compound is more preferable. Further, two or more platinum group element compounds may be used in combination, but also in this case, it is preferable to use a palladium compound as a main catalyst component.
[0036]
As the palladium compound, usually, a palladium compound having a valency of II or IV is used, and its form is a salt or a complex salt.
[0037]
Examples of the palladium compound include palladium acetate, palladium cyanide, palladium fluoride, palladium chloride, palladium bromide, palladium iodide, palladium nitrate, palladium sulfate, palladium oxide, palladium hydroxide, dichloro (cyclooctadiene) palladium, Examples thereof include dichloro (norbornadiene) palladium, dichlorobis (triphenylphosphine) palladium, sodium tetrachloropalladate, ammonium hexachloropalladate, and potassium tetracyanopalladate.
[0038]
Among these palladium compounds, palladium acetate, palladium nitrate, palladium sulfate, palladium chloride, sodium tetrachloropalladate and ammonium hexachloropalladate are preferred, and palladium acetate, palladium nitrate and palladium chloride are more preferred.
[0039]
Examples of rhodium compounds include, for example, rhodium chloride, rhodium bromide, rhodium iodide, rhodium nitrate, rhodium sulfate, rhodium acetate, rhodium formate, rhodium propionate, rhodium butyrate, rhodium valerate, rhodium naphthenate, rhodium acetylacetonate, and oxidation. Rhodium, rhodium trihydroxide and the like can be mentioned.
[0040]
In the present invention, both the solution-based hydrogenation and the latex-based hydrogenation catalyst are used as a supported catalyst in which a catalyst component is supported on a carrier and charged into a reaction system.
[0041]
The carrier of the supported catalyst may be any carrier that is generally used as a carrier of the metal catalyst, but in the catalyst recovery step described below, the carrier must be capable of adsorbing the complex of the platinum group element-containing catalyst. There is. Specifically, activated carbon generally used as an adsorbent; inorganic compounds containing silicon, aluminum, magnesium and the like are preferable. Among them, in order to increase the adsorption efficiency of the catalyst, the average of the properties of the carrier is preferably It is preferable to use one having a particle diameter of 10 nm to 100 nm and a specific surface area of 200 to 2000 m ² / g.
Such a carrier is appropriately selected from known catalyst carriers such as activated carbon, activated clay, talc, clay, alumina gel, silica gel, diatomaceous earth, and synthetic zeolite. Examples of the method for supporting the catalyst component on the carrier include an impregnation method, a coating method, a spray method, and a precipitation method. The supported amount of the catalyst component is usually 0.5 to 80% by weight, preferably 1 to 50% by weight, more preferably 2 to 30% by weight in terms of the ratio of the catalyst component to the total amount of the catalyst and the carrier. The carrier supporting the catalyst component can be formed into, for example, a spherical shape, a columnar shape, a polygonal columnar shape, a honeycomb shape, or the like, depending on the type of the reactor and the reaction type. The supported catalyst may be added as it is to a solution-based hydrogenation or latex-based reaction system.
[0042]
The temperature of the hydrogenation reaction is usually 0 to 200C, preferably 5 to 150C, more preferably 10 to 100C. An excessively high reaction temperature is not desirable because side reactions such as hydrogenation of a nitrile group may occur. On the other hand, if the reaction temperature is excessively low, the reaction rate decreases, which is not practical.
[0043]
The pressure of hydrogen is usually 0.1 to 20 MPa, preferably 0.1 to 15 MPa, and more preferably 0.1 to 10 MPa. The reaction time is not particularly limited, but is usually 30 minutes to 50 hours. Note that it is preferable to first pressurize the hydrogen gas after substituting the reaction system with an inert gas such as nitrogen and further substituting with hydrogen.
[0044]
The hydrogenation reaction of the solution system and the latex system in step (A) can be performed under basic conditions to improve the reaction efficiency and reduce the amount of the hydrogenation catalyst used. The method for carrying out the reaction under basic conditions is not particularly limited, and can be appropriately selected depending on the reaction system of the solution-based hydrogenation and the reaction system of the latex-based hydrogenation.
[0045]
For example, in solution-based hydrogenation, a method of keeping the polymer in contact with a basic aqueous solution at the stage of preparing a conjugated diene-based polymer rubber (raw material) to be subjected to a hydrogenation reaction; A method of adding a basic compound to the reaction system; The pH of the hydrogenation reaction solution is preferably 7.2 to 13, more preferably 7.5 to 12.5, and further preferably 8.0 to 12.
[0046]
In the latex-based hydrogenation, a basic compound is directly added to the reaction system so that the pH of the hydrogenation reaction solution (latex) measured by a pH meter becomes more than 7. Examples of the method and timing include a method of adding a basic compound to the latex before adding the catalyst to the hydrogenation reaction solution; a method of adding a basic compound after the start of the hydrogenation reaction; and the like.
[0047]
The basic compound for making the hydrogenation reaction solution or the catalyst solution basic is not particularly limited, and examples thereof include an alkali metal compound, an alkaline earth metal compound, ammonia, an ammonium salt compound, and an organic amine compound. Preferred are alkali metal compounds and alkaline earth metal compounds.
[0048]
Examples of the alkali metal compound include hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; carbonate compounds such as lithium carbonate, sodium carbonate, and potassium carbonate; lithium hydrogen carbonate, sodium hydrogen carbonate, and potassium hydrogen carbonate Oxides such as lithium oxide, potassium oxide and sodium oxide; organic acid salt compounds such as potassium acetate and sodium acetate; lithium methoxide, lithium ethoxide, sodium methoxide, sodium ethoxide and potassium alkoxides such as t-butoxide; phenoxides such as sodium phenoxide and potassium phenoxide; and the like. Preferred are hydroxides, carbonate compounds and bicarbonate compounds of alkali metals, more preferably hydroxides.
[0049]
Examples of the alkaline earth metal compound include, for example, hydroxides, carbonate compounds, bicarbonate compounds, oxides, organic acid salt compounds, alkoxides, and phenoxides of alkaline earth metals such as magnesium, calcium, strontium, and barium. Is mentioned. Preferred are hydroxides, carbonate compounds and bicarbonate compounds, and more preferred are hydroxides.
[0050]
Examples of the ammonium salt compound include ammonium carbonate and ammonium hydrogen carbonate. Examples of the organic amine compound include aliphatic, alicyclic, and aromatic mono- and polyamino compounds, such as triethylamine, ethanolamine, morpholine, N-methylmorpholine, pyridine, hexamethylenediamine, dodecamethylenediamine, and xylylenediamine. Examples include amines.
[0051]
These basic compounds can be used as they are, or can be used after being diluted or dissolved with water or an organic solvent such as alcohol or ketone. The basic compounds may be used alone or in combination of two or more, and the amount used may be appropriately selected so that the hydrogenation reaction solution or the catalyst solution exhibits basicity.
[0052]
A major feature of the production method according to the present invention is that, as a post-treatment method of the above-mentioned reaction step (A), a complexation treatment step (B) of treating a catalyst (catalyst residue) contained in a reaction mixture with a complexing agent. Is provided.
[0053]
The complexing agent used in the step (B) is not particularly limited as long as it has a complexing ability of the platinum group element-containing catalyst, and is appropriately selected depending on the reaction system of the solution hydrogenation and the latex hydrogenation. can do. The complexing method is also not particularly limited, and the complexing can be carried out by adding a predetermined amount of a complexing agent as it is or as a solution of an organic solvent or water to the reaction mixture and stirring.
[0054]
Examples of the complexing agent include ammonia; ammonium salts of organic or inorganic acids such as ammonium acetate, ammonium benzoate, and ammonium sulfate; Preferred are ammonia and ammonium acetate, and more preferred is ammonia.
[0055]
The amount of the complexing agent to be used is generally 1 to 50 times, preferably 2 to 30 times, the mole of the platinum group element contained in the catalyst used in the hydrogenation reaction in step (A). The complexing time is usually 10 minutes to 20 hours, preferably 30 minutes to 10 hours, and the complexing temperature is usually 0 to 100 ° C.
[0056]
In the production method of the present invention, a catalyst recovery step (C) is provided subsequent to the above-described complexation step (B). That is, a complex of the platinum group element-containing catalyst which has been complexed in the step (B) and is present in the reaction mixture and desorbed from the carrier is re-supported on the carrier, and is recovered from the reaction mixture. The reloading is performed by bringing the complex into contact with the carrier by, for example, stirring and mixing the reaction mixture. Specifically, the contact temperature is preferably 40 to 90 ° C., and the contact time is 10 minutes to 10 hours.
In the complexing treatment step (B), after the catalyst has been complexed by the complexing agent, the complexed product is re-supported by stirring and mixing the reaction mixture without changing the temperature of the reaction mixture. It can also be carried.
[0057]
The catalyst recovery step (C) is a step of re-supporting the complex of the desorption catalyst and separating and recovering the carrier from the reaction mixture. Since the unremoved catalyst is also supported on the carrier on which the complex is re-supported, by recovering the carrier, both the desorbed catalyst and the catalyst remaining on the carrier without being removed are combined. Can be collected.
[0058]
The method of recovering the carrier on which the complex is re-supported is not particularly limited, and a known solid-liquid separation method can be employed depending on each of the reaction systems of the solution hydrogenation and the latex hydrogenation. That is, by directly applying a separation operation such as filtration or centrifugation, the carrier can be easily separated and recovered from the reaction mixture.
[0059]
In the production method of the present invention, by employing the steps (B) and (C) as described above, it is not necessary to add an adsorbent or the like again for the recovery of the catalyst desorbed from the support and perform the recovery operation. Almost all, almost all of the platinum group element-containing catalyst used in the step (A) can be efficiently separated and recovered by a single operation.
[0060]
In the catalyst recovery method of the present invention, it is preferable to perform an oxidation treatment on the reaction mixture before performing the complexation treatment in the step (B). After completion of the hydrogenation reaction, the catalyst containing the platinum group element that is desorbed from the carrier and is present in the system is present in a reduced state, such as in a hydrogenated polymer. , Easily separated from the hydrogenated polymer. By complexing the reaction mixture thus oxidized, the platinum group element-containing catalyst is more easily re-adsorbed to the carrier.
[0061]
The oxidizing agent is not particularly limited as long as it has catalytic oxidizing ability, and can be appropriately selected depending on the reaction system of solution-based hydrogenation and latex-based hydrogenation.
[0062]
Examples of the oxidizing agent in the case of the solution hydrogenation include iodine; iron halides such as ferric chloride (FeCl ₃ ); and peroxides such as hydrogen peroxide, peracetic acid, and perbenzoic acid; and the like. Is ferric chloride, iodine, more preferably ferric chloride. Examples of the oxidizing agent in the case of latex hydrogenation include air (oxygen); peroxides such as hydrogen peroxide, peracetic acid, and perbenzoic acid; and the like. More preferred is hydrogen peroxide.
[0063]
The use amount of these oxidizing agents is not particularly limited, and is 1 to 100 moles, preferably 3 to 50 moles, based on the platinum group element contained in the catalyst used for the hydrogenation reaction. The contact temperature is usually 0 to 100 ° C, preferably 50 to 95 ° C, more preferably 70 to 90 ° C. The contact time is usually 10 minutes to 20 hours, preferably 30 minutes to 10 hours.
[0064]
The method of contacting the catalyst with the oxidizing agent is not uniform depending on the type of the oxidizing agent, but can be appropriately selected depending on the reaction system of the solution-based hydrogenation and the latex-based hydrogenation. For example, when applying an oxidizing agent such as ferric chloride, iodine, hydrogen peroxide or the like to the solution-based hydrogenation step, a predetermined amount thereof may be added to the reaction mixture and stirred. When air is used as the oxidizing agent in the latex-based hydrogenation step, a method of continuously blowing air into the reaction mixture in an open state; converting the gaseous atmosphere of the reaction mixture container in an open or closed state to air. And a method of stirring the reaction mixture. When hydrogen peroxide is used, it may be added to the reaction mixture and stirred.
[0065]
In the solution-based hydrogenation, after separating the carrier supporting the catalyst in the step (C), the organic solvent is distilled off by a known method to obtain a hydrogenated conjugated diene-based polymer.
[0066]
In the latex-based hydrogenation, a hydrogenated conjugated diene-based polymer latex from which the hydrogenation catalyst has been almost completely removed is obtained, so that it can be directly used as a latex product. The content of the platinum group element in the latex (per polymer) is usually 300 ppm or less, preferably 100 ppm or less. Further, by coagulating and drying the polymer latex by a known method, a hydrogenated conjugated diene-based polymer rubber from which a hydrogenation catalyst has been almost removed can be obtained.
[0067]
Hydrogenation rate of hydrogenated conjugated diene-based polymer obtained by the production method of the present invention (ratio of hydrogenated carbon-carbon double bond to total carbon-carbon double bond present in polymer before reaction) ) Can be arbitrarily controlled in the range of 1 to 100%. The hydrogenation rate represented by the iodine value is preferably 120 or less. Such a hydrogenated conjugated diene-based polymer has a small amount of a hydrogenation catalyst, and thus does not deteriorate the contacting material, is excellent in transparency, and can be easily obtained as a colored product. Can be used in applications.
[0068]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Parts and% in these examples are by weight unless otherwise specified.
[0069]
After recovery of the hydrogenation catalyst, the amount of palladium in the separated hydrogenated conjugated diene polymer rubber was determined by carbonizing / ashing a part of the hydrogenated polymer rubber at 600 ° C., dissolving it in sulfuric acid, and performing atomic absorption analysis. It was measured by the method.
[0070]
Example 1
An autoclave was charged sequentially with 2 parts of potassium oleate, 180 parts of ion-exchanged water, 37 parts of acrylonitrile, and 0.5 part of t-dodecyl mercaptan. After the inside of the reactor was replaced with nitrogen, 63 parts of butadiene were sealed. The reactor was cooled to 10 ° C., and 0.01 part of cumene hydroperoxide and 0.01 part of ferrous sulfate were added. The contents were then stirred for 16 hours while maintaining the reactor at 10 ° C. Thereafter, a 10% aqueous solution of hydroquinone was added to the reactor to terminate the polymerization, thereby obtaining an acrylonitrile-butadiene copolymer (NBR). Unreacted monomers were removed from the polymerization reaction solution to obtain a latex. The polymerization conversion was 90%.
[0071]
The latex was dropped into the coagulated water while stirring at 50 ° C. 300 parts of coagulated water in which 3 parts of calcium chloride (coagulant) had been dissolved. An aqueous solution of potassium hydroxide was added thereto to precipitate a polymer crumb while maintaining the pH at 11.5. The crumb was separated from the coagulated water, washed with water, and dried at 50 ° C. under reduced pressure. This crumb was dissolved in acetone to prepare a 15% polymer solution. A carbon-supported palladium (Pd) catalyst (Pd loading rate: 2%, Pd content: 500 ppm by Pd metal / NBR ratio, average particle diameter: 10 nm, specific surface area of carbon: 800 m) ² / g), and the mixture was charged into an autoclave equipped with a stirrer, and nitrogen gas was flowed for 10 minutes to remove dissolved oxygen. After purging the system twice with hydrogen gas, 5 MPa of hydrogen was pressurized. The contents were heated to 50 ° C. and stirred for 6 hours to carry out a hydrogenation reaction.
[0072]
After the completion of the hydrogenation reaction, the system was cooled to room temperature and the hydrogen in the system was replaced with nitrogen. 1.84 parts of ferric chloride was added to the reaction mixture, and the mixture was stirred at 30 ° C. for 3 hours (oxidation treatment). Next, 16 parts of aqueous ammonia was added, and the mixture was stirred at 80 ° C. for 5 hours to perform a complexing treatment. Since the formed complex was immediately re-supported on the carrier, the carrier was recovered from the reaction mixture by filtration. The obtained filtrate was put into 10 times the volume of water, and the precipitated rubber was taken out. It was dried in a vacuum drier for 24 hours to obtain hydrogenated NBR. The amount of palladium in this hydrogenated NBR was 50 ppm, and the recovery rate with respect to the amount of palladium desorbed from the carrier and used in the hydrogenation reaction (200 ppm with respect to hydrogenated NBR) was 75%.
[0073]
Example 2
The procedure was performed except that a silica-supported Pd catalyst (Pd loading rate: 2%, Pd amount: 500 ppm by Pd metal / NBR ratio, average particle diameter: 17 nm, silica specific surface area: 260 m ² / g) was used instead of palladium carbon. The same operation as in Example 1 was performed to obtain hydrogenated NBR. The amount of palladium in this hydrogenated NBR was 60 ppm, and the recovery rate with respect to the amount of palladium desorbed from the carrier and used in the hydrogenation reaction (200 ppm with respect to hydrogenated NBR) was 70%.
[0074]
Comparative Example 2
In the same manner as in Example 1, preparation of NBR (polymerization conversion: 90%), preparation of an acetone solution thereof, and hydrogenation reaction were sequentially performed. The reaction mixture was stirred at 30 ° C. for 3 hours without adding the ferric chloride used in Example 1. Next, 16 parts of water was added without adding the aqueous ammonia used in Example 2, and the mixture was stirred at 80 ° C. for 5 hours. Thereafter, the same treatment as in Example 1 was performed to obtain hydrogenated NBR. The amount of palladium in this hydrogenated NBR was 190 ppm, and the recovery from the amount of palladium desorbed from the support and used in the hydrogenation reaction (200 ppm relative to hydrogenated NBR) was only 5%.
[0075]
As is clear from the above Examples and Comparative Examples, when the complexing treatment is not performed as a post-treatment method after completion of the hydrogenation reaction (Comparative Example 1), the palladium content in the obtained hydrogenated NBR is reduced. It turns out that it is very different. On the other hand, it was confirmed that by performing the complexing treatment, the catalyst used for the hydrogenation reaction was re-adsorbed to the support and could be efficiently separated from the reaction mixture (Examples 1 and 2).
[0076]
【The invention's effect】
According to the catalyst recovery method of the present invention, the platinum-group-element-containing catalyst detached from the support and present in the polymer solution is re-loaded on the support, and the platinum-group-element-containing catalyst can be efficiently recovered by a single separation treatment. . Also, since the platinum group element-containing catalyst can be easily recovered and reused, there is no problem in economical efficiency even if a large amount of catalyst is used, and various hydrides, particularly hydrogenated conjugated diene-based polymers, are industrially advantageous. This has the effect of being able to be manufactured at a high speed. Further, the hydrogenated polymer obtained by applying the method for producing a hydrogenated conjugated diene-based polymer of the present invention has a small amount of residual catalyst, and therefore has no adverse effect on the quality of latex products and rubber products.

Claims (4)

A platinum group element-containing catalyst desorbed from a support, which is contained in the reaction mixture by adding a complexing agent to a reaction mixture of a hydrogenation reaction carried out in the presence of a platinum group element-containing catalyst supported on a support. And recovering the complex from the reaction mixture by re-supporting the complex on the carrier. The catalyst recovery method according to claim 1, wherein the oxidation treatment of the reaction mixture is performed before adding the complexing agent. 3. The method according to claim 1, wherein the platinum group element is palladium. A hydrogenation reaction step (A) of hydrogenating the conjugated diene-based polymer in the presence of a platinum group element-containing catalyst supported on a support; a complexing agent for converting the platinum group element-containing catalyst desorbed from the support into a reaction mixture (B); a catalyst recovery step (C) in which a complex of a platinum group element-containing catalyst is re-supported on the carrier and the carrier is recovered from the reaction mixture. A method for producing a hydrogenated conjugated diene polymer.