JP2004141694A - Recovery method of hydrogenation catalyst - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently separate and recover a platinum group element in a used hydrogenation catalyst from a reaction mixture after the carbon-carbon unsaturated bond of a polymer is subjected to hydrogenation reaction. <P>SOLUTION: This recovery method of hydrogenation catalyst includes a process (1) for bringing the hydrogenation reaction mixture, which is obtained by the hydrogenation reaction of the carbon-carbon unsaturated bond of the polymer in the presence of the platinum group element-containing hydrogenation catalyst, into contact with water, a process (2) for separating a hydride and water and a process (3) for precipitating or flocculating the platinum group element-containing hydrogenation catalyst present in water by adding a flocculant to the water separated in the process (2) to recover the same. <P>COPYRIGHT: (C)2004,JPO

Description

【００４６】
表１より、セラム水に、それぞれ、硫酸アルミニウム、含鉄硫酸アルミニウム及び硫酸第一鉄を添加して凝集処理を行なった場合に、セラム水中のＰｄ濃度は当初の１ｐｐｍから０．０１ｐｐｍ（検出限界）以下にまで低減されていることがわかる。また、セラム水中のＰｄ回収率は、いずれも８５％以上であり、特に硫酸第一鉄を用いたものが回収率が９６％と最も優れていた。
【００４７】
実施例４
実施例１〜３でＰｄ回収率の最も高かった硫酸第一鉄を凝集剤として用い、以下の操作でテストを行った（テストに用いた装置は図１参照）。
１．実施例１と同様にして得られたＰｄ濃度１ｐｐｍのセラム水を、容積約１．５ｍ^３の凝集反応槽１（無機凝集剤用）に導入した。攪拌翼を用い、翼先端速度４．１９ｍ／ｓにて反応槽内のセラム水を急速攪拌しながら、硫酸第一鉄の水溶液を、セラム水中の濃度が０．０６％となるよう添加した。さらにセラム水に硫酸水溶液及び水酸化ナトリウム水溶液を添加してセラム水のｐＨを６〜８に調整し、１５分間撹拌した。
２．凝集反応槽１の後工程に容積約１．５ｍ^３の凝集反応槽２（高分子凝集剤用）を設け、反応槽１内のスラム水と凝集物を全て移送し、高分子凝集剤（アクリル酸ナトリウム塩とアクリルアミドとの共重合体（陰イオン性ポリマー）及びポリアクリルアミド（非イオン性ポリマー）を１：１の重量比で混合したものの０．２％水溶液）をセラム水に対して１．２×１０^−６％となるように添加し、翼先端速度：２．３ｍ／ｓにて１５分間緩速攪拌を行った。
３．凝集反応終了後、沈降分離機（シックナー）により固液分離を行った。この際、沈降時間を３０分以上確保し、沈殿物を十分に沈降させた。
４．沈殿物として得られた固形分を、脱水機により含水率が３０％程度になるまで脱水し、ドライヤーにより乾燥させ、固形分を得た。
５．得られた固形分からＰｄを精製・回収した。
６．分離されたセラム水のＰｄ濃度は０．０１ｐｐｍ以下、沈殿物中のＰｄ濃度は５５００μｇ／ｇであり、回収率は９０％であった。
【００４８】
【発明の効果】
本発明により、有機化合物、特に重合体の炭素−炭素不飽和結合の水素化反応を行った後、使用した白金族元素含有水素化触媒を反応混合物から効率よく分離回収する方法を提供することができる。
【図面の簡単な説明】
【図１】図１は本発明方法工程（３）の一実施態様である凝集反応設備の概略図である。
【符号の説明】
１…　セラム水
２…　凝集剤（硫酸第一鉄）
３…　凝集反応槽１
４…　水酸化ナトリウム水溶液
５…　硫酸水溶液
６…　凝集反応槽２
７…　高分子凝集剤
８…　固液分離槽
９…　脱水・乾燥機
１０…固形分
１１…回収パラジウム[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for recovering a hydrogenation catalyst used in a hydrogenation reaction of an organic compound, and more particularly to a method for recovering a hydrogenation catalyst used in a hydrogenation reaction of an organic compound in the presence of a platinum group element-containing hydrogenation catalyst. About.
[0002]
[Prior art]
As a useful means for modifying a polymer, for example, a conjugated diene-based polymer, a method for selectively or partially hydrogenating a carbon-carbon double bond of the polymer is known, and hydrogenated acrylonitrile-butadiene is commonly used. Hydrogenated conjugated diene-based polymers such as polymers are produced on an industrial scale.
In the above-mentioned hydrogenation process, as the hydrogenation catalyst, any of a heterogeneous catalyst insoluble in a solution in which the raw material polymer is dissolved (for example, a supported catalyst) and a homogeneous catalyst soluble in the solution can be used. In the case of the former hydrogenation catalyst, it can be recovered from the reaction mixture by filtration or centrifugation, and in the case of the latter hydrogenation catalyst, by adsorption or the like or by insolubilization and filtration or centrifugation.
[0003]
After the operation for recovering the hydrogenation catalyst, the reaction mixture is brought into contact with water containing a coagulant to coagulate and recover the hydrogenated conjugated diene-based polymer. However, a small amount of the unrecovered hydrogenation catalyst remains in the reaction mixture, and most of them are transferred to the water containing the coagulant. Conventionally, these hydrogenation catalysts have been disposed of together with the wastewater. However, if these hydrogenation catalysts can be recovered and reused, the amount of the hydrogenation catalyst newly used when the hydrogenation reaction is repeatedly performed can be reduced, and the metal concentration of the wastewater can be reduced. Therefore, a technique for efficiently recovering the hydrogenation catalyst in the wastewater has been desired.
[0004]
[Problems to be solved by the invention]
In view of the above circumstances, an object of the present invention is to efficiently separate and recover the used platinum group element-containing hydrogenation catalyst from the reaction mixture after performing a hydrogenation reaction of carbon-carbon unsaturated bonds of an organic compound, particularly a polymer. Is to provide a way to
[0005]
[Means for Solving the Problems]
The present inventors have conducted intensive studies on the hydrogenation reaction of an organic solvent solution of a conjugated diene polymer in order to solve the above-mentioned problems.As a result, the hydrogenation reaction mixture was brought into contact with water containing a coagulant. When a flocculant such as ferrous sulfate is added to waste water (serum water) containing a trace amount of a platinum group element-containing hydrogenation catalyst at a few ppm level, the catalyst precipitates or flocculates and precipitates, and sedimentation and separation They have found that they can be easily recovered by centrifugation, and have completed the present invention based on this finding.
[0006]
Thus, according to the present invention, the following (1) to (7) are provided.
1. A step (1) of bringing a hydrogenation reaction mixture obtained by a hydrogenation reaction in the presence of a platinum group element-containing hydrogenation catalyst into contact with water, a step (2) of separating a hydride and water, and the step (2). A method for recovering a hydrogenation catalyst, comprising a step (3) of adding a flocculant to the separated water to precipitate or aggregate and recover the hydrogenation catalyst containing a platinum group element present in the water.
2. 2. The hydrogenation catalyst recovery method according to the above item 1, wherein the content of the platinum group element-containing hydrogenation catalyst in the water separated in the step (2) is 10 ppm or less in terms of the concentration of the platinum group element.
3. 3. The method for recovering a hydrogenation catalyst according to the above 1 or 2, wherein the object of the hydrogenation reaction is a conjugated diene polymer.
4. 4. The method for recovering a hydrogenation catalyst according to any one of the above items 1 to 3, wherein the coagulant is a metal sulfate.
5. 5. The method for recovering a hydrogenation catalyst according to any one of the above 1 to 4, wherein the coagulant is at least one selected from the group consisting of aluminum sulfate, iron-containing aluminum sulfate, and iron sulfate.
6. 6. The method for recovering a hydrogenation catalyst according to the above 4 or 5, wherein after adding the metal sulfate, a polymer flocculant is further added to precipitate or aggregate the hydrogenation catalyst containing a platinum group element.
7. The method for recovering a hydrogenation catalyst according to any one of the above 1 to 6, wherein the pH of the water containing the coagulant is adjusted to 5 to 9 to precipitate or coagulate the hydrogenation catalyst containing a platinum group element.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
The method for recovering a hydrogenation catalyst according to the present invention is characterized by including the following steps, and preferably includes the following steps in the following order.
Step (1): a step of bringing a hydrogenation reaction mixture obtained by a hydrogenation reaction in the presence of a platinum group element-containing hydrogenation catalyst into contact with water.
Step (2): Step of separating hydride and water
Step (3): A step of adding a flocculant to the water separated in the step (2), thereby precipitating or aggregating the platinum group element-containing catalyst present in the water and recovering the same.
[0008]
In the step (1), a reaction mixture containing a hydride obtained by hydrogenating an object of a hydrogenation reaction (an object of a hydrogenation reaction) in the presence of a platinum group element-containing hydrogenation catalyst is brought into contact with water. It is a process.
[0009]
The target of the hydrogenation reaction to which the method of the present invention can be applied is not limited as long as it is an organic compound that can be hydrogenated in the presence of a platinum group element-containing catalyst, and the hydrogenation reaction using the target of such a hydrogenation reaction is not limited. For example, hydrogenation of acetylene to ethylene, hydrogenation of 3-hexyn-1-ol to cis-3-hexen-1-ol, and the like to the conversion of an acetylene bond to a carbon-carbon double bond. Hydrogenation reaction: represented by hydrogenation of gasoline (improvement of gasoline quality), production of isooctane from diisobutylene, production of saturated glyceride from unsaturated glyceride, production of hydrogenated conjugated diene polymer from conjugated diene polymer, etc. Hydrogenation of a carbon-carbon double bond to a saturated bond; hydrogenation of a carbonyl group producing the corresponding alcohol from cyclopentanone or cyclohexanone; Hydrogenation reaction to convert tolyl or azomethine group (the Schiff base) to an amino group; and the like.
The method of the present invention can be most suitably applied to a hydrogenation reaction of a carbon-carbon double bond to a saturated bond, in particular, a hydrogenation reaction of a conjugated diene polymer.
[0010]
The conjugated diene-based polymer is obtained by combining at least one conjugated diene monomer or at least one monomer copolymerizable with the conjugated diene monomer with the conjugated diene monomer to obtain a conventionally known emulsion. It can be produced by a polymerization method or a solution polymerization method.
[0011]
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.
[0012]
Examples of the monomer copolymerizable with the conjugated diene monomer include α, β-ethylenically unsaturated nitrile monomers such as acrylonitrile, methacrylonitrile, and crotononitrile; acrylic acid, methacrylic acid, crotonic acid Α, β-ethylenically unsaturated carboxylic acids such as fumaric acid, maleic acid, and itaconic acid; methyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth) Α, β-ethylenically unsaturated carboxylic acid esters such as trifluoroethyl acrylate; α, β-ethylenically unsaturated carboxylic acid amides such as acrylamide and methacrylamide; styrene, α-methylstyrene, p-methylstyrene, divinylbenzene Vinyl aromatic compounds such as vinyl acetate; vinyl esters such as vinyl acetate and vinyl propionate Le; vinyl ether compounds such as fluoroethyl vinyl ether; and the like.
[0013]
The method of the present invention is suitably applied to a conjugated diene-based polymer having an α, β-ethylenically unsaturated nitrile monomer as a copolymer component among monomers copolymerizable with these conjugated diene monomers. It is most suitably applied to a conjugated diene polymer having an acrylonitrile monomer as a copolymer component.
[0014]
Although the monomer composition ratio in the conjugated diene polymer is not particularly limited, the method of the present invention comprises 5 to 100% by weight of a conjugated diene monomer and 95 to 0% by weight of a monomer copolymerizable therewith, It is most preferably applied to a conjugated diene-based polymer having preferably 10 to 90% by weight of a conjugated diene monomer and 90 to 10% by weight of a monomer copolymerizable therewith.
[0015]
When producing a conjugated diene polymer, known polymerization initiators and molecular weight regulators may be used. 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. In the case of emulsion polymerization, the emulsifier used is not particularly limited, and an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, and the like can be used, but 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.
[0016]
The hydrogenation reaction is performed on the raw material mixture containing the target of the hydrogenation reaction in the presence of a platinum group element-containing hydrogenation catalyst. As the raw material mixture, one in which an object of the hydrogenation reaction is dissolved or dispersed in water or an organic solvent is used. When the object of the hydrogenation reaction is the conjugated diene-based polymer, the raw material mixture is preferably an aqueous dispersion or an organic solvent solution of the polymer. The conjugated diene-based polymer is obtained by polymerizing a conjugated diene monomer alone or a monomer mixture containing these monomers by the above-mentioned known method. When an aqueous dispersion of the polymer is used as the raw material mixture, the aqueous dispersion obtained by emulsion polymerization can be used as the aqueous dispersion. When an organic solvent solution of the polymer is used as the raw material mixture, the solution is prepared by collecting the polymer from the latex and dissolving the polymer in an organic solvent such as acetone.
[0017]
The hydrogenation reaction can be performed by a method known as a method for hydrogenating the target of each hydrogenation reaction. The platinum group element-containing hydrogenation catalyst used for the hydrogenation reaction is a simple substance of the platinum group element (ruthenium, rhodium, palladium, osmium, iridium or platinum) or a compound thereof. Examples of the form of the platinum group element compound include salts and complexes.
In the present invention, a palladium compound and a rhodium compound are preferably used from the viewpoints of catalytic activity and availability, and more preferably a palladium compound is used. 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.
[0018]
As the palladium compound, a salt or complex of II-valent or IV-valent palladium is usually used.
Examples of palladium salts include palladium acetate, palladium cyanide, palladium fluoride, palladium chloride, palladium bromide, palladium iodide, palladium nitrate, palladium sulfate, palladium oxide, and palladium hydroxide.
Examples of the palladium complex include dichloro (cyclooctadiene) palladium, dichloro (norbornadiene) palladium, dichlorobis (triphenylphosphine) palladium, sodium tetrachloropalladate, ammonium hexachloropalladate, and potassium tetracyanopalladate.
Among these palladium compounds, salts such as palladium acetate, palladium nitrate, palladium sulfate and palladium chloride; complexes such as sodium tetrachloropalladate and ammonium hexachloropalladate; are preferable, and palladium acetate, palladium nitrate and palladium chloride and the like are preferable. Are more preferred.
[0019]
As the rhodium compound, usually, a rhodium salt is used. Specifically, rhodium chloride, rhodium bromide, rhodium iodide, rhodium nitrate, rhodium sulfate, rhodium acetate, rhodium formate, rhodium propionate, rhodium butyrate, rhodium valerate, rhodium naphthenate, rhodium acetylacetonate, rhodium oxide And rhodium trihydroxide.
[0020]
The hydrogenation catalyst may be used by dissolving or dispersing the compound containing the platinum group element in the reaction system as it is, or may be used by being supported on a carrier and dispersed in the reaction system.
The 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.
[0021]
The hydrogenation reaction mixture contains the hydride of the object of the above-mentioned hydrogenation reaction. Specifically, the hydride is dissolved or dispersed in water or an organic solvent. In the case where the hydride is a conjugated diene polymer hydride, usually, when the raw material mixture is a polymer organic solvent solution, the hydrogenation reaction mixture is also obtained in a hydrogenated polymer organic solvent solution state, When the raw material mixture is a polymer latex, the hydrogenation reaction mixture is also obtained in a hydrogenated polymer latex state.
[0022]
The platinum group element-containing hydrogenation catalyst used for the hydrogenation reaction is usually dissolved or dispersed in the reaction mixture. Therefore, it is preferable to recover most of the reaction mixture before contact with water, which will be described later. Specifically, when the hydrogenation catalyst is dispersed in the reaction mixture, the hydrogenation catalyst can be separated and recovered from the reaction mixture by a method such as filtration, centrifugation, and pressure sedimentation. When the hydrogenation catalyst is dissolved in the reaction mixture, the reaction is performed by a method such as adsorption or extraction, or after insolubilizing the catalyst, by a method such as filtration, centrifugation, and pressure sedimentation. Most of the hydrogenation catalyst can be separated and recovered from the mixture. These methods may be based on known methods such as a catalyst removal method and a catalyst demineralization method generally used in the field of chemical reactions. In these methods, in order to facilitate the recovery of the catalyst, a compound that promotes precipitation, aggregation, and the like can be present in the reaction mixture.
[0023]
When the hydride is a conjugated diene-based polymer hydride, the recovery of the hydrogenation catalyst is facilitated by the presence of an oxidizing agent or a complexing agent in the reaction mixture.
The oxidizing agent is not particularly limited as long as it has catalytic oxidizing ability, and iodine; ferric chloride (FeCl 2) ₃ )); Peroxides such as hydrogen peroxide, peracetic acid, and perbenzoic acid; and the like, but are preferably ferric chloride, iodine, and more preferably ferric chloride.
[0024]
Examples of the complexing agent include ammonia; ammonium salts of organic or inorganic acids such as ammonium acetate, ammonium benzoate, and ammonium sulfate; allylating agents such as allyl Grignard reagent; and the like, with ammonia and ammonium acetate being preferred. , Ammonia is more preferred.
Any one of these oxidizing agents and complexing agents may be used alone, or two or more thereof may be used in combination. It is preferable to use them in combination.
[0025]
In this step (1), the hydrogenation reaction mixture is brought into contact with water. Thereby, the hydride is precipitated or aggregated. The contact between the hydrogenation reaction mixture and water is preferably performed by stirring and mixing in order to promote hydride precipitation and aggregation. When the hydride is a polymer hydride such as a conjugated diene-based polymer, the contact with water is typified by an operation generally known as a coagulation operation.
When the hydrogenation reaction mixture is an emulsion of the above-mentioned hydride of a conjugated diene polymer, specifically, the emulsion is mixed with water containing a coagulant.
[0026]
The water to be brought into contact with the hydrogenation reaction mixture is appropriately temperature, depending on the type of the hydride, the presence or absence of components other than water, and the content thereof, so that the precipitation or aggregation of the hydride proceeds sufficiently. It is preferable to set the conditions.
When the hydride is a hydride of a conjugated diene polymer, it is preferable to add a coagulant to water. As the coagulant, a compound generally known as a coagulant for rubber can be used.
[0027]
By bringing the hydrogenation reaction mixture into contact with water, a mixture in which the hydride is dispersed in water (a water dispersion of a hydride) is obtained. Water, which is a hydride dispersion medium, may contain components such as an organic solvent contained in the hydrogenation reaction mixture. When the hydride is a conjugated diene polymer, the dispersion medium usually contains an emulsifier used for polymerization, a coagulant used for coagulation, and an organic solvent when an organic solvent is used. I have. The hydride of the conjugated diene-based polymer is usually dispersed in the water as an aggregate (so-called polymer crumb) having a particle size of about 0.2 to several tens mm.
[0028]
Step (2) of the method of the present invention is a step of separating the hydride and water in the aqueous dispersion of the hydride obtained in step (1). Specific methods of separation include methods such as filtration, centrifugation, and sedimentation. When the hydride is a conjugated diene-based polymer, the polymer crumb and water can be separated using a metal mesh or the like.
[0029]
Step (3) of the method of the present invention is a step in which a coagulant is added to the water separated in step (2) to precipitate or coagulate the platinum group element-containing hydrogenation catalyst present in the water and collect it. .
It is preferable that most of the hydrogenation reaction catalyst is recovered in the step (1), but it is practically difficult to recover 100% of the hydrogenation catalyst. It remains at a level of 10 ppm or less. The hydrogenation catalyst is usually dissolved or dispersed in water, and may be in the form of a platinum group element alone (including ions), or a metal organic compound such as an oxide, a halide and a complex, or an ion thereof. Exists.
This step (3) comprises adding a coagulant to water containing a platinum group element-containing hydrogenation catalyst at a level of several tens of ppm or less. Thereby, the catalyst can be precipitated or aggregated and recovered efficiently.
[0030]
In the present invention, the content of the platinum group element-containing hydrogenation catalyst in the water separated in step (2) is a value converted to the concentration of the platinum group element, preferably 10 ppm or less, more preferably 5 ppm or less, More preferably, it is 2 ppm or less.
[0031]
The flocculant used in step (3) is not particularly limited, and a compound generally known as a flocculant for water treatment, such as an inorganic flocculant and an organic flocculant, can be used.
As the inorganic coagulant, a metal salt is usually used. Examples of the type of metal include aluminum and iron. Examples of the type of the salt include a sulfate and a halide.
Specifically, aluminum salts such as aluminum sulfate, iron-containing aluminum sulfate, sodium aluminate, and aluminum chloride; iron such as ferrous sulfate, iron chloride, ferric sulfate, and a complex salt of ferric sulfate and iron chloride; Salts; and the like.
[0032]
As the organic flocculant, a polymer flocculant is usually used. Examples of the polymer flocculant include an anionic polymer, a cationic polymer, and a nonionic polymer. Examples of the anionic polymer include sodium alginate, sodium polyacrylate, a partially hydrolyzed salt of polyacrylamide, and a maleic acid copolymer of polyacrylic acid. Examples of the cationic polymer include a water-soluble aniline resin, polythiourea, polyethyleneimine, polyvinylpyridine and the like. Non-ionic polymers include polyacrylamide, polyoxyethylene, and the like.
[0033]
In the present invention, among these coagulants, metal sulfates such as aluminum sulfate, iron-containing aluminum sulfate and ferrous sulfate are preferred, and ferrous sulfate is most preferred.
The amount of the coagulant to be added is usually 100 to 1500 times, preferably 300 to 1000 times, more preferably 400 to 800 times, based on the weight of the platinum group element. If the addition amount of the flocculant is too small, the precipitation or agglomeration of the platinum group element-containing hydrogenation catalyst is insufficient, and the catalyst recovery rate is lowered. There is a possibility that the recovery of the waste may become difficult or a complicated operation may be required.
[0034]
When the above metal salt is used as the coagulant, it is preferable to use a polymer coagulant in combination. By using a polymer flocculant in combination, the flocculent easily grows to an appropriate size, and the recovery becomes easier. As the polymer coagulant to be used in combination, an anionic polymer such as sodium polyacrylate and sodium alginate; a nonionic polymer such as polyacrylamide and polyoxyethylene are preferable, and a combination of these is more preferable. When combined, the ratio is 1/10 to 10/1 in terms of anionic polymer / nonionic polymer (by weight). The amount of the polymer coagulant to be added is 0.001 to 0.1 part by weight, preferably 0.01 to 0.1 part by weight, based on 100 parts by weight of the metal salt.
[0035]
In the step (3), it is preferable to adjust the pH of the water to which the coagulant is added to 5 to 9 to precipitate or coagulate the platinum group element-containing hydrogenation catalyst, and to adjust the pH to 6 to 8. More preferred. The pH can be adjusted by adding an acidic solution and / or an alkaline solution. In the present invention, it is preferable to adjust the amount by adding an aqueous solution of sulfuric acid and / or an aqueous solution of sodium hydroxide.
The pH is most preferably adjusted after the addition of the metal salt and before the addition of the polymer flocculant. The reason is that if the pH at the time of adding the metal salt is too low, poor precipitation or poor aggregation may occur.
[0036]
After adding the coagulant, the conditions for depositing or coagulating the platinum group element-containing hydrogenation catalyst include a temperature of 10 ° C. or more, preferably 20 ° C. or more. If the temperature is too low, aggregation may not proceed sufficiently. As for the stirring conditions, for example, when stirring is performed with a stirring blade, the blade tip speed is preferably 0.5 to 20 m / sec, more preferably 0.8 to 10 m / sec, and still more preferably 1 to 10 m / sec. 5 m / sec. If the stirring speed is too slow, aggregation may not proceed sufficiently, while if too fast, flocs of aggregates may collapse and be crushed.
Furthermore, in the present invention, when a metal salt and a polymer flocculant are used in combination, the blade tip speed is relatively high after the addition of the metal salt and relatively slow after the addition of the polymer flocculant in the above range. Is preferred. The reason is that after the addition of the metal salt, it is necessary to increase the stirring speed to increase the contact efficiency between the platinum group element-containing hydrogenation catalyst and the metal salt in order to form a coagulation nucleus. This is because it is necessary to keep the stirring speed at an optimum speed in order to grow the once formed aggregate to such a degree that the floc is not crushed and to a sufficient size.
[0037]
According to the above method, it is preferable to grow the precipitates and aggregates of the platinum group element-containing hydrogenation catalyst to an average particle diameter of 50 to 500 μm, and more preferably to 100 to 300 μm.
For the recovery of the platinum group element-containing hydrogenation catalyst, a method known as a solid-liquid separation method can be adopted. preferable.
[0038]
【Example】
Hereinafter, the method of the present invention will be described in more detail with reference to Examples and Comparative Examples, taking the hydrogenation reaction of a conjugated diene polymer as an example, but the present invention is not limited to these Examples. Absent. Parts and% in these examples are by weight unless otherwise specified.
[0039]
In the following Examples, the platinum group element (palladium) concentration in water and the recovery of palladium (Pd) are measured by the following methods.
(1) Pd concentration in water
To about 50 g of the sample (water containing Pd), 0.5 mL each of sulfuric acid and nitric acid is added and boiled on a heater. After concentrating to about 2.7 mL, pure water was added to adjust to 10 mL, and measurement was performed by inductively coupled high-frequency plasma emission spectroscopy (ICP-AES). Specifically, it is measured by the internal calibration method using SPS-5000 manufactured by Seiko Instruments Inc.
[0040]
(2) Pd recovery rate
The amount of Pd recovered was determined from the concentration of the solid content in water formed by adding the flocculant and the Pd concentration in the solid content measured by the following method, and calculated from the Pd concentration in the water before the flocculant addition determined by the above method. The ratio with respect to the Pd amount thus obtained is defined as a Pd recovery rate.
(Analysis of Pd concentration of solid content)
20 mL of pure water, 1.5 mL of sulfuric acid and 0.5 mL of nitric acid are added to about 0.2 g of the sample (Pd-containing solid content), and the mixture is heated and decomposed by a heater. When white sulfuric acid smoke is generated, pure water is added and heated to dissolve Pd. Further, it is adjusted to 30 mL with pure water and measured by ICP-AES.
[0041]
(Reference example) Production of conjugated diene polymer
In an autoclave, 2 parts by weight of potassium oleate, 180 parts by weight of ion-exchanged water, 37 parts by weight of acrylonitrile, and 0.5 part by weight of t-dodecylmercaptan (molecular weight modifier) were sequentially charged. After replacing the inside of the reactor with nitrogen, 63 parts by weight of butadiene were sealed. The reactor was cooled to 10 ° C., and 0.01 part by weight of cumene hydroperoxide (polymerization catalyst) and 0.01 part by weight of ferrous sulfate were added. Next, the contents were mixed well by rotating the reactor for 16 hours while maintaining the reactor at 10 ° C. Thereafter, a 10% by weight aqueous solution of hydroquinone was added to the reactor to terminate the polymerization. The polymerization conversion was 90%. The polymerization reaction solution was stirred at 30 ° C. for 3 hours to remove unreacted butadiene. Next, the mixture was heated to 50 ° C., and unreacted acrylonitrile was removed under reduced pressure.
[0042]
300 parts of coagulated water in which 3 parts of calcium chloride were dissolved as a coagulant was kept at 50 ° C., and the polymerization reaction solution was dropped therein, and the copolymer rubber was coagulated into crumbs. Dry under reduced pressure.
[0043]
Comparative Example 1
The polymer obtained in Reference Example 1 was dissolved in acetone to prepare a 15% by weight raw material polymer solution for a hydrogenation reaction. An autoclave was charged with 60 parts of the solution, and 0.09 parts of palladium acetate was added. After the inside of the system was replaced with nitrogen and further twice with hydrogen, the reaction was performed at a hydrogen pressure of 5 MPa and 50 ° C. for 6 hours.
After completion of the reaction, the reaction mixture was cooled to room temperature, and hydrogen in the system was replaced with nitrogen. Hydrogen peroxide (oxidizing agent) and ammonia (complexing agent) were added to this solution, the temperature was raised to 80 ° C. with stirring, and the state was maintained for 5 hours. The solution after the treatment was passed through activated carbon for treatment. The water was heated to 100 ° C. 100 times the amount of the polymer, the reaction mixture was added dropwise to the hot water, and the mixture was stirred to obtain an aqueous dispersion (slurry) of polymer crumb while evaporating and removing acetone. . The slurry was passed through a wire mesh to separate polymer crumb and water (serum water). The Pd concentration in the separated serum water was 1 ppm.
[0044]
Examples 1-3
Using the conjugated diene polymer obtained in Reference Example 1, a serum water containing 1 ppm of Pd was obtained in the same manner as in Comparative Example 1. Using the obtained serum water and three kinds of metal sulfates shown in Table 1 below as an inorganic flocculant, Pd flocculation treatment corresponding to step (3) was performed according to the following procedure.
1. Add an aqueous solution of metal sulfate to serum water
2. Further, the pH of the aqueous solution is adjusted to around 6.5 by adding a sodium hydroxide solution.
3. Using a stirring blade, the mixture is stirred at 150 rpm for 30 minutes.
4. A 0.25% aqueous solution of a mixture of a polymer coagulant (a copolymer (anionic polymer) of sodium acrylate and acrylamide (anionic polymer) and polyacrylamide (nonionic polymer) in a weight ratio of 1: 1 to an aqueous solution. .003 mL), reduce the number of revolutions to 50 rpm, and stir for an additional 30 minutes.
5. The solution was allowed to stand for 1 hour, the precipitate was separated from the supernatant, the respective Pd concentrations were measured, and the Pd recovery was calculated. The results are shown in Table 1.
[0045]
[Table 1]

[0046]
According to Table 1, when aluminum sulfate, iron-containing aluminum sulfate, and ferrous sulfate were added to serum water to perform coagulation treatment, the Pd concentration in the serum water was initially 1 ppm to 0.01 ppm (detection limit). It can be seen that it has been reduced to the following. Further, the recovery rate of Pd in the serum water was 85% or more in each case, and the recovery rate using ferrous sulfate was particularly excellent at 96%.
[0047]
Example 4
Using ferrous sulfate having the highest Pd recovery rate in Examples 1 to 3 as a coagulant, a test was performed by the following operation (see FIG. 1 for the apparatus used for the test).
1. Serum water having a Pd concentration of 1 ppm obtained in the same manner as in Example 1 was used for a volume of about 1.5 m. ³ (Inorganic flocculant). While rapidly stirring the serum water in the reaction tank at a blade tip speed of 4.19 m / s using a stirring blade, an aqueous solution of ferrous sulfate was added so that the concentration in the serum water became 0.06%. Further, an aqueous solution of sulfuric acid and an aqueous solution of sodium hydroxide were added to the serum water to adjust the pH of the serum water to 6 to 8, and the mixture was stirred for 15 minutes.
2. Approximately 1.5 m ³ A coagulation reaction tank 2 (for a polymer flocculant) is provided, and all of the slum water and coagulates in the reaction tank 1 are transferred, and a polymer coagulant (a copolymer of sodium acrylate and acrylamide (anionic Polymer) and polyacrylamide (non-ionic polymer) in a 1: 1 weight ratio of a 0.2% aqueous solution) in a ratio of 1.2 × 10 ^-6 %, And slowly stirred for 15 minutes at a blade tip speed of 2.3 m / s.
3. After completion of the agglutination reaction, solid-liquid separation was performed using a sedimentation separator (thickener). At this time, the sedimentation time was secured for 30 minutes or more, and the sediment was sufficiently settled.
4. The solid content obtained as a precipitate was dehydrated by a dehydrator until the water content became about 30%, and dried by a drier to obtain a solid content.
5. Pd was purified and recovered from the obtained solid content.
6. The Pd concentration of the separated serum water was 0.01 ppm or less, the Pd concentration in the precipitate was 5,500 μg / g, and the recovery was 90%.
[0048]
【The invention's effect】
According to the present invention, it is possible to provide a method for efficiently separating and recovering a used platinum group element-containing hydrogenation catalyst from a reaction mixture after performing a hydrogenation reaction of carbon-carbon unsaturated bonds of an organic compound, particularly a polymer. it can.
[Brief description of the drawings]
FIG. 1 is a schematic view of an agglutination reaction facility which is an embodiment of the method step (3) of the present invention.
[Explanation of symbols]
1. Serum water
2. Coagulant (ferrous sulfate)
3. Coagulation reaction tank 1
4: Sodium hydroxide aqueous solution
5 ... sulfuric acid aqueous solution
6 ... Coagulation reaction tank 2
7 ... Polymer flocculant
8 Solid-liquid separation tank
9 ... Dehydration / drying machine
10: Solid content
11… Recovered palladium

Claims (7)

A step (1) of bringing a hydrogenation reaction mixture obtained by a hydrogenation reaction in the presence of a platinum group element-containing hydrogenation catalyst into contact with water, a step (2) of separating a hydride and water, and the step (2) (3) a step of adding a flocculant to the water separated in step (1), thereby precipitating or aggregating the platinum group element-containing hydrogenation catalyst present in the water to recover the hydrogenated catalyst. The hydrogenation catalyst recovery method according to claim 1, wherein the content of the platinum group element-containing hydrogenation catalyst in the water separated in the step (2) is 10 ppm or less in terms of a concentration of the platinum group element. The method for recovering a hydrogenation catalyst according to claim 1 or 2, wherein the object of the hydrogenation reaction is a conjugated diene polymer. The method for recovering a hydrogenation catalyst according to any one of claims 1 to 3, wherein the coagulant is a metal sulfate. The method for recovering a hydrogenation catalyst according to any one of claims 1 to 4, wherein the coagulant is at least one selected from the group consisting of aluminum sulfate, iron-containing aluminum sulfate, and iron sulfate. The method for recovering a hydrogenation catalyst according to claim 4 or 5, wherein after addition of the metal sulfate, a polymer flocculant is further added to precipitate or aggregate the hydrogenation catalyst containing a platinum group element. The method for recovering a hydrogenation catalyst according to any one of claims 1 to 6, wherein the pH of the water containing the coagulant is adjusted to 5 to 9 to precipitate or coagulate the hydrogenation catalyst containing a platinum group element.

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