Method for producing aldehyde, method for producing alcohol, and catalyst composition

Abstract

A method for producing an aldehyde includes: subjecting an olefin to a hydroformylation reaction with a gas containing hydrogen and carbon monoxide in the presence of a catalyst; withdrawing part or all of a reaction solution having accumulated therein a high-boiling-point byproduct from a reaction zone; mixing the withdrawn reaction solution with a poor solvent for the catalyst in a mixing tank to precipitate an aggregate containing the catalyst and the high-boiling-point byproduct; and adhering the precipitated aggregate to an inner surface of the mixing tank to recover the aggregate.

Description

Method for producing aldehyde, method for producing alcohol, and catalyst composition

[0001] The present invention relates to a method for producing an aldehyde, a method for producing an alcohol, and a catalyst composition.

[0002] The method of producing aldehydes by hydroformylating an olefinically unsaturated organic compound with carbon monoxide and hydrogen in the presence of a long-form Group 8 to 10 metal-phosphine complex catalyst is well known as a method of producing aldehydes. This hydroformylation reaction is also called the "oxo reaction." The hydrogen (H ２ A mixture of argon (CO) and carbon monoxide (CO) is called "oxo gas."

[0003] Since the catalyst used in the hydroformylation reaction of olefins contains an expensive metal of Groups 8 to 10 of the long-form periodic table, such as rhodium, it is ideal to use the catalyst semi-permanently. Therefore, the following methods are usually used: a method in which the reaction product is separated from the reaction solution, and the reaction solution containing the catalyst, which is a distillation residue, is circulated to the reaction zone for reuse; or a method in which the reaction product is distilled away from the reaction zone by gas stripping and separated, and the reaction solution containing the catalyst is left in the reaction zone and the reaction is continued continuously.

[0004] In the hydroformylation reaction, high-boiling by-products such as aldehyde condensation by-products are generated and accumulate, so it is necessary to continuously or intermittently withdraw a portion of the reaction liquid outside the reaction zone (the reaction zone may be referred to as the reaction system). Since the withdrawn reaction liquid contains the catalyst, particularly the expensive metals of Groups 8 to 10 of the long periodic table, in addition to the high-boiling by-products, it is extremely important to efficiently recover this catalyst from both an economical and environmental pollution prevention perspective.

[0005] Patent Document 1 discloses a method in which a hydroformylation reaction liquid in which high-boiling by-products have accumulated and been extracted from a reaction zone is mixed with alcohol and water, contacted with hydrogen gas at 30°C, and then cooled to 0°C, whereby a rhodium-phosphine complex catalyst in which hydrogen atoms are coordinated is crystallized and recovered.

[0006] Patent Document 2 discloses a method in which an alcohol, water, and hydrogen are mixed with a hydroformylation reaction liquid in which high-boiling by-products have accumulated and been extracted from a reaction zone, and the mixture is maintained at 10 to 30°C, thereby precipitating and recovering a rhodium-phosphine complex catalyst in which hydrogen is coordinated.

[0007] Patent Document 3 discloses a method for reactivating a deactivated catalyst by treating an alkylphosphine produced by partially substituting a ligand such as triarylphosphine with an alkyl group of an α-olefin with a sufficient amount of oxygen or an oxygen-containing gas at about 20 to 80°C to convert it into the corresponding phosphine oxide.

[0008] Patent Document 4 discloses a method in which a hydroformylation reaction liquid in which high-boiling by-products have accumulated and been extracted from a reaction zone is mixed with alcohol and water, brought into contact with hydrogen gas at 30°C, and then cooled to 0°C, whereby a rhodium-phosphine complex catalyst in which hydrogen atoms are coordinated is crystallized and recovered.

[0009] International Publication No. 2019-098242 JP 2006-151826 A JP 57-87845 A JP 57-122948 A

[0010] In the methods disclosed in Patent Documents 1 to 4, it is necessary to first crystallize the rhodium-phosphine complex catalyst in a state where high-boiling by-products have been removed as much as possible, recover non-sticky crystals, and then filter the recovered crystals to separate the rhodium-phosphine complex catalyst crystals from the crystallization mother liquor. In Patent Documents 1 to 4, a large amount of the rhodium-phosphine complex catalyst is lost in this filtration process, making it impossible to recover a sufficient amount of the rhodium-phosphine complex catalyst.

[0011] An object of the present invention is to solve these problems. An object of the present invention is to provide a method for producing an aldehyde that can recover, in high yield, an expensive complex catalyst, particularly an expensive metal of Groups 8 to 10 of the long form of the periodic table, contained in the complex catalyst, from a hydroformylation reaction solution. Another object of the present invention is to provide a method for producing an alcohol by producing an aldehyde by the above-mentioned method for producing an aldehyde and then producing an alcohol from the aldehyde. A further object of the present invention is to provide a catalyst composition that can recover, in high yield, an expensive complex catalyst, particularly an expensive metal of Groups 8 to 10 of the long form of the periodic table, used in reactions such as hydroformylation.

[0012] The present inventors have found that by mixing a poor solvent for the catalyst with the reaction mixture after the hydroformylation reaction, and subjecting the mixture to an agglomeration treatment in a state containing the catalyst and high-boiling by-products, and recovering the agglomerates as sticky aggregates, the complex catalyst can be recovered in a higher yield than by conventional methods.

[0013] The invention was achieved based on these findings and is summarized as follows.

[0014] [1] A method for producing an aldehyde, comprising subjecting an olefin to a hydroformylation reaction with a gas containing hydrogen and carbon monoxide in the presence of a catalyst, and mixing a poor solvent for the catalyst with a part or all of a reaction liquid extracted from a reaction zone to precipitate a sticky aggregate containing the catalyst.

[0015] [2] The method for producing an aldehyde according to [1], wherein a distribution ratio of high-boiling by-products contained in the aggregate is 4.0 mass% or more when the total mass of high-boiling by-products contained in the reaction liquid is 100 mass%.

[0016] [3] The method for producing an aldehyde according to [1] or [2], comprising mixing a poor solvent for the catalyst with a part or all of the reaction solution in a mixing tank, and allowing the precipitated aggregate to adhere to the inner surface of the mixing tank, or allowing the aggregate to precipitate in an aggregated state in the mixing tank.

[0017] [4] A method for producing an aldehyde, comprising subjecting an olefin to a hydroformylation reaction with a gas containing hydrogen and carbon monoxide in the presence of a catalyst, and mixing a poor solvent for the catalyst with a part or all of a reaction liquid extracted from a reaction zone to precipitate an aggregate containing the catalyst, wherein the distribution rate of high-boiling by-products in the aggregate is 4.0 mass% or more when the total mass of the high-boiling by-products contained in the reaction liquid is taken as 100 mass%.

[0018] [5] The method for producing an aldehyde according to [4], comprising mixing a poor solvent for the catalyst with a part or all of the reaction solution in a mixing tank, and allowing the precipitated aggregate to adhere to the inner surface of the mixing tank, or allowing the aggregate to precipitate in an aggregated state in the mixing tank.

[0019] [6] A method for producing an aldehyde, comprising subjecting an olefin to a hydroformylation reaction with a gas containing hydrogen and carbon monoxide in the presence of a catalyst, the method comprising: withdrawing a part or all of a reaction liquid in which high-boiling by-products have accumulated from a reaction zone; mixing the withdrawn reaction liquid with a poor solvent for the catalyst in a mixing vessel to precipitate an aggregate containing the catalyst and the high-boiling by-products; and adhering the precipitated aggregate to the inner surface of the mixing vessel and recovering it.

[0020] [7] The method for producing an aldehyde according to [6], wherein the aggregate has adhesiveness under the precipitation conditions.

[0021] [8] The method for producing an aldehyde according to [6] or [7], wherein a distribution ratio of the high-boiling by-products in the aggregate is 4.0 mass% or more when the total mass of the high-boiling by-products contained in the withdrawn reaction liquid is 100 mass%.

[0022] [9] The method for producing an aldehyde according to any one of [1] to [8], wherein the precipitated coagulate is supplied to a hydroformylation reaction zone.

[0023]

[10] The method for producing an aldehyde according to [9], wherein the precipitated aggregate is dissolved in a good solvent for the catalyst and supplied to a hydroformylation reaction zone.

[0024]

[11] The method for producing an aldehyde according to any one of [1] to

[10] , wherein the precipitation is carried out under neutral to acidic conditions.

[0025]

[12] The method for producing an aldehyde according to any one of [1] to

[11] , wherein the catalyst is a long-form metal-organophosphorus complex catalyst selected from Groups 8 to 10 of the periodic table.

[0026]

[13] The method for producing an aldehyde according to

[12] , wherein the catalyst is a long-form metal-phosphite complex catalyst selected from metals of Groups 8 to 10 of the periodic table.

[0027]

[14] The method for producing an aldehyde according to

[12] or

[13] , wherein the metal of Groups 8 to 10 of the long form periodic table is rhodium.

[0028]

[15] The method for producing an aldehyde according to any one of [1] to

[14] , wherein the poor solvent contains water and an alcohol.

[0029]

[16] The method for producing an aldehyde according to

[15] , wherein the poor solvent is a mixture of water and an alcohol, and the content of the water is 12 to 40 mass% with respect to 100 mass% of the total mass of the mixture.

[0030]

[17] The method for producing an aldehyde according to any one of [1] to

[16] , wherein the aggregate is precipitated under a temperature condition of 0°C or higher and 70°C or lower.

[0031]

[18] A method for producing an alcohol, comprising producing an aldehyde by the method according to any one of [1] to

[17] , and producing an alcohol from the aldehyde.

[0032]

[19] A catalyst composition comprising a catalyst and high-boiling by-products, wherein the catalyst is a long-form Group 8 to 10 metal-organophosphorus complex catalyst of the periodic table, and the content of the high-boiling by-products is 30 mass% or more, based on 100% by total mass of the catalyst composition.

[0033]

[20] The catalyst composition according to

[19] , wherein the catalyst composition has adhesiveness.

[0034]

[21] The catalyst composition according to

[19] or

[20] , wherein the catalyst is a catalyst for producing an aldehyde by hydroformylation of an olefin.

[0035]

[22] The catalyst composition according to any one of

[19] to

[21] , wherein the catalyst is a long-form metal-phosphite complex catalyst selected from metals of Groups 8 to 10 of the Periodic Table.

[0036]

[23] The catalyst composition according to any one of

[19] to

[22] , wherein the metal of Groups 8 to 10 of the long form periodic table is rhodium.

[0037]

[24] A method for producing an aldehyde, comprising: dissolving the catalyst composition according to any one of

[19] to

[23] in a good solvent for the catalyst to obtain a catalyst solution; and carrying out a hydroformylation reaction of an olefin in the presence of the catalyst solution.

[0038] According to the present invention, there is provided a method for producing an aldehyde, which enables the recovery of a complex catalyst, particularly an expensive Group 8 to 10 metal in the long form of the Periodic Table, from a hydroformylation reaction solution in high yield.The present invention also provides a method for producing an alcohol using an aldehyde produced by this method for producing an aldehyde.Furthermore, according to the present invention, there is provided a catalyst composition recovered in the above-mentioned method for producing an aldehyde.

[0039] Figure 1 is a graph showing the relationship between the distribution rate of high-boiling by-products in the agglomerates or crystallized products and the rhodium recovery rate in Examples 1 to 10 and Comparative Example 1. Figure 2(a) is a photograph of the appearance of the mixing tank after agglomeration obtained in Example 2, showing an example of a state in which agglomerates adhere to the inner surface of the mixing tank and the reaction liquid after the reaction has undergone solid-liquid separation. Figure 2(b) is a photograph of the appearance of the mixing tank after crystallization obtained in Comparative Example 1, showing an example of a state in which crystallized products do not adhere to the inner surface of the mixing tank and the reaction liquid after the reaction has formed a uniform slurry without undergoing solid-liquid separation.

[0040] The present invention will be described in detail below. The present invention is not limited to the following description, and can be practiced in any modified form without departing from the gist of the present invention.

[0041] Unless otherwise specified, in this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. For example, "A to B" means A or more and B or less.

[0042] 1. Method for Producing Aldehyde A first embodiment of the method for producing an aldehyde of the present invention is a method for producing an aldehyde, comprising subjecting an olefin to a hydroformylation reaction with a gas containing hydrogen and carbon monoxide in the presence of a catalyst (hereinafter, this step may be referred to as a "hydroformylation reaction step"), and further comprising mixing a poor solvent for the catalyst with part or all of the reaction liquid withdrawn from a reaction zone (hereinafter, this step may be referred to as a "reaction liquid withdrawal step") to precipitate a sticky aggregate containing the catalyst (hereinafter, this step may be referred to as an "aggregation step").

[0043] Furthermore, in the method for producing an aldehyde according to the first embodiment of the present invention, it is preferable that the distribution ratio of the high-boiling by-products contained in the aggregate is 4.0 mass% or more when the total mass of the high-boiling by-products contained in the reaction liquid is 100 mass%. Furthermore, in the method for producing an aldehyde according to the first embodiment of the present invention, a poor solvent for the catalyst is mixed with part or all of the reaction liquid in a mixing tank, and the precipitated aggregate can be attached to the inner surface of the mixing tank or precipitated in an aggregated state within the mixing tank.

[0044] A second embodiment of the method for producing an aldehyde of the present invention is a method for producing an aldehyde, comprising: subjecting an olefin to a hydroformylation reaction with a gas containing hydrogen and carbon monoxide in the presence of a catalyst (hereinafter, this step may be referred to as a "hydroformylation reaction step"); and further comprising mixing a poor solvent for the catalyst with a part or all of the reaction liquid withdrawn from the reaction zone (hereinafter, this step may be referred to as a "reaction liquid withdrawal step") to precipitate an aggregate containing the catalyst (hereinafter, this step may be referred to as an "aggregation step"). When the total mass of the high-boiling by-products contained in the reaction liquid is taken as 100 mass%, the distribution ratio of the high-boiling by-products in the aggregate is 4.0 mass% or more.

[0045] Furthermore, in the method for producing an aldehyde according to the second embodiment of the present invention, a poor solvent for the catalyst is mixed with a part or all of the reaction solution in a mixing tank, and the precipitated aggregates can be attached to the inner surface of the mixing tank, or can be precipitated in an aggregated state within the mixing tank.

[0046] A third embodiment of the method for producing an aldehyde of the present invention is a method for producing an aldehyde, comprising: subjecting an olefin to a hydroformylation reaction with a gas containing hydrogen and carbon monoxide in the presence of a catalyst (hereinafter, this step may be referred to as a "hydroformylation reaction step"); withdrawing a part or all of a reaction liquid in which high-boiling-point by-products have accumulated from a reaction zone (hereinafter, this step may be referred to as a "reaction liquid withdrawal step"); mixing the withdrawn reaction liquid with a poor solvent for the catalyst in a mixing tank to precipitate an aggregate containing the catalyst and the high-boiling-point by-products (hereinafter, this step may be referred to as an "aggregation step"); and adhering the precipitated aggregate to an inner surface of the mixing tank and recovering it (hereinafter, this step may be referred to as a "recovery step").

[0047] In the present invention, when a poor solvent for the catalyst is mixed with the reaction solution extracted from the hydroformylation reaction zone, a sticky precipitate containing the catalyst and high-boiling by-products is formed, as shown in the examples described below. Because this precipitate is sticky and not in a crystalline state, the term "crystallized product" does not adequately describe it. Therefore, in the present invention, this precipitate is referred to as an "aggregate" to distinguish it from the non-adhesive precipitates formed in the conventional method and the comparative examples described below. On the other hand, the non-adhesive precipitates formed in the conventional method and the comparative examples described below are also referred to as "crystallized product." Furthermore, as described above, the tank in which the reaction solution and the poor solvent for the catalyst are mixed is referred to as a "mixing tank," and the "precipitation" of the "aggregate" in this "mixing tank" is referred to as an "aggregation treatment," and this process is referred to as an "aggregation step." In contrast, the "precipitation" of the "crystallized product" as in the conventional method and the comparative examples described below is referred to as a "crystallization treatment."

[0048] As used herein, the term "internal surface of a mixing vessel" refers to a portion in the mixing vessel where the flow of the reaction liquid is slow, a portion against which aggregates of the reaction liquid are pressed during stirring, or a portion in the mixing vessel having the shape of a protrusion, and specifically includes the bottom surface and inner wall of the mixing vessel, baffles, stirring blades and shaft, the surface of a side tube, etc. Furthermore, as used herein, the terms "reaction zone" and "hydroformylation reaction zone" refer to a zone including a reactor for carrying out a hydroformylation reaction and peripheral equipment for the reactor, such as a gas-liquid separator, associated with the reactor.

[0049] The catalyst composition of the present invention is a catalyst composition comprising a catalyst and high-boiling by-products, wherein the catalyst is a long-form Group 8 to 10 metal-organophosphorus complex catalyst, and the content of the high-boiling by-products is 30 mass% or more, relative to 100% by total mass of the catalyst composition.

[0050] First, the hydroformylation reaction according to the first, second, and third embodiments of the process for producing an aldehyde of the present invention (hereinafter, these may be collectively referred to as "the present invention") will be described, and then the reaction liquid withdrawing step, the flocculation step, and the recovery step will be described for each step.

[0051] [Hydroformylation Reaction] [Catalyst] In the present invention, the catalyst used in the hydroformylation reaction is not particularly limited as long as it has catalytic activity in the hydroformylation reaction of an olefin. Because of its excellent reaction activity, it is preferable to use an organophosphorus complex catalyst of a metal of Groups 8 to 10 of the long form periodic table (hereinafter referred to as "Groups 8 to 10 metal") as the catalyst used in the hydroformylation reaction.

[0052] In the present invention, the Group 8 to 10 metals are metals belonging to Groups 8 to 10 of the long-form periodic table. Among these, ruthenium, cobalt, rhodium, palladium, and platinum are preferred because of their high activity when used as catalysts, and rhodium is particularly preferred because of its high activity.

[0053] As the organophosphorus ligand compound for forming a Group 8 to 10 metal-organophosphorus complex catalyst, any trivalent organophosphorus compound commonly used to function as a monodentate or polydentate ligand for a Group 8 to 10 metal can be used. Among these, organophosphorus compounds that serve as monodentate ligands include tertiary triorganophosphines represented by the following formula (I):

[0054]

[0055] (In formula (I), each R independently represents a substituted or unsubstituted monovalent hydrocarbon group.)

[0056] Examples of the monovalent hydrocarbon group represented by R include an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an aryl group having 3 to 12 carbon atoms, an alkylaryl group having 6 to 24 carbon atoms, and an arylalkyl group having 6 to 24 carbon atoms. That is, examples of the triorganophosphine include a trialkylphosphine, a triarylphosphine, a tricycloalkylphosphine, an alkylarylphosphine, a cycloalkylarylphosphine, and an alkylcycloalkylphosphine.

[0057] Substituents that the monovalent hydrocarbon group may have include, but are not limited to, alkyl groups, alkoxy groups, and the like.

[0058] Specific examples of triorganophosphines include tributylphosphine, trioctylphosphine, triphenylphosphine, tritolylphosphine, tricycloalkylphosphine, monobutyldiphenylphosphine, dipropylphenylphosphine, cyclohexyldiphenylphosphine, etc. Among these, triphenylphosphine is preferred because it is chemically stable due to its low activity and is easily available.

[0059] Other examples of the trivalent organic phosphorus compound that can be used include trivalent phosphite compounds represented by the following formulas (1) to (10).

[0060] <Trivalent phosphite compound represented by formula (1)>

[0061] (In formula (1), R １ ~R ３ each independently represents a monovalent hydrocarbon group which may have a substituent.

[0062] R １ ~R ３ Examples of the monovalent hydrocarbon group represented by the formula (I) which may have a substituent include an alkyl group, an aryl group, and a cycloalkyl group.

[0063] Specific examples of the compound represented by formula (1) include trialkyl phosphites such as trimethyl phosphite, triethyl phosphite, n-butyldiethyl phosphite, tri-n-butyl phosphite, tri-n-propyl phosphite, tri-n-octyl phosphite, and tri-n-dodecyl phosphite; triaryl phosphites such as triphenyl phosphite and trinaphthyl phosphite; and alkylaryl phosphites such as dimethylphenyl phosphite, diethylphenyl phosphite, and ethyldiphenyl phosphite. Furthermore, for example, bis(3,6,8-tri-t-butyl-2-naphthyl)phenyl phosphite and bis(3,6,8-tri-t-butyl-2-naphthyl)(4-biphenyl)phenyl phosphite, as described in JP-A-6-122642, may also be used. Among these, triphenyl phosphite is the most preferred.

[0064] <Trivalent phosphite compound represented by formula (2)>

[0065] (In formula (2), R ４ represents a divalent hydrocarbon group which may have a substituent. ５ represents a monovalent hydrocarbon group which may have a substituent.

[0066] R ４Examples of the divalent hydrocarbon group which may have a substituent include an alkylene group which may contain an oxygen, nitrogen, sulfur atom, etc. in the middle of the carbon chain; a cycloalkylene group which may contain an oxygen, nitrogen, sulfur atom, etc. in the middle of the carbon chain; a divalent aromatic group such as phenylene or naphthylene; a divalent aromatic group in which a divalent aromatic ring is bonded directly or via an alkylene group or an atom such as oxygen, nitrogen or sulfur; and a divalent aromatic group and an alkylene group which are bonded directly or via an atom such as oxygen, nitrogen or sulfur.

[0067] R ５ Examples of the monovalent hydrocarbon group include an alkyl group, an aryl group, and a cycloalkyl group.

[0068] Examples of the compound represented by formula (2) include compounds described in U.S. Pat. No. 3,415,906, such as neopentyl(2,4,6-t-butyl-phenyl)phosphite and ethylene(2,4,6-t-butyl-phenyl)phosphite.

[0069] <Trivalent phosphite compound represented by formula (3)>

[0070] (In formula (3), R １０ is R in the above formula (2) ５ Ar is synonymous with １ and Ar ２ each independently represents an aryl group which may have a substituent; x and y each independently represent 0 or 1; Q is -CR １１ R １２ -, -O-, -S-, -NR １３ -, -SiR １４ R １５ and —CO—. １１ and R １２ R each independently represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a phenyl group, a tolyl group, or an anisyl group. １３ , R １４ and R １５ each independently represents a hydrogen atom or a methyl group; and n represents 0 or 1.

[0071] Specific examples of the trivalent phosphite compound represented by formula (3) include compounds described in U.S. Pat. No. 4,599,206 such as 1,1'-biphenyl-2,2'-diyl-(2,6-di-t-butyl-4-methylphenyl)phosphite, and compounds described in U.S. Pat. No. 4,717,775 such as 3,3'-di-t-butyl-5,5'-dimethoxy-1,1'-biphenyl-2,2'-diyl(2-t-butyl-4-methoxyphenyl)phosphite.

[0072] <Trivalent phosphite compound represented by formula (4)>

[0073] (In formula (4), R ６ represents a trivalent hydrocarbon group which may have a cyclic or acyclic substituent.

[0074] Examples of the compound represented by formula (4) include compounds described in US Pat. No. 4,567,306, such as 4-ethyl-2,6,7-trioxa-1-phosphabicyclo-[2,2,2]-octane.

[0075] <Trivalent phosphite compounds represented by formulas (5) and (6)>

[0076] (In formula (5), R ７ is R in the above formula (3) ４ It is synonymous with R ８ and R ９ each independently represents a hydrocarbon group which may have a substituent; a and b each represent an integer of 0 to 6; the sum of a and b is 2 to 6; and X represents a hydrocarbon group having a valence of (a+b).

[0077] Of the compounds represented by formula (5), preferred examples include compounds represented by the following formula (6), including compounds described in JP-A Nos. 62-116535 and 62-116587:

[0078]

[0079] (In formula (6), X is alkylene, arylene, or -Ar １ - (CH ２ )x-Qn-(CH２ ) y-Ar ２ represents a divalent group selected from the group consisting of Ar １ , Ar ２ , Q, x, y, and n are Ar in the above formula (3). １ , Ar ２ , Q, x, y, n.)

[0080] <Trivalent phosphite compound represented by formula (7)>

[0081] (In formula (7), X, Ar １ , Ar ２ , Q, x, y, and n are X and Ar in the above formula (3). １ , Ar ２ , Q, x, y, n. １８ is R in the above formula (2) ４ is synonymous with

[0082] <Trivalent phosphite compound represented by formula (8)>

[0083] (In formula (8), R １９ and R ２０ each independently represents an aromatic hydrocarbon group, and at least one of the aromatic hydrocarbon groups has a hydrocarbon group on the carbon atom adjacent to the carbon atom to which the oxygen atom is bonded. m represents an integer of 2 to 4. Each -O-P(OR １９ ) (OR ２０ ) groups may be different from each other. X represents an m-valent hydrocarbon group which may have a substituent.

[0084] Among the compounds represented by formula (8), for example, the compounds described in JP-A No. 5-178779 are preferred.

[0085] <Trivalent phosphite compound represented by formula (9)>

[0086] (In formula (9), R ２１ ~R ２４ R each independently represents a hydrocarbon group which may have a substituent. ２１ and R ２２ , R ２３ and R ２４may be bonded to each other to form a ring. W represents a divalent aromatic hydrocarbon group which may have a substituent. L represents a saturated or unsaturated divalent aliphatic hydrocarbon group which may have a substituent.

[0087] As the compound represented by formula (9), for example, the compound described in JP-A-8-259578 can be used.

[0088] <Trivalent phosphite compound represented by formula (10)>

[0089] (In formula (10), R ２５ ~R ２８ represents a monovalent hydrocarbon group which may have a substituent. ２５ and R ２６ , R ２７ and R ２８ may be bonded to each other to form a ring. A and B each independently represent a divalent hydrocarbon group which may have a substituent. n represents an integer of 0 or 1.

[0090] R ２５ ~R ２８ Examples of the optionally substituted monovalent hydrocarbon group represented by the formula (I) include an alkyl group, an aryl group, a cycloalkyl group, etc. The optionally substituted divalent hydrocarbon group represented by A and B may be any of aromatic, aliphatic, and alicyclic.

[0091] <Bisphosphite compound represented by formula (11)>

[0092] In formula (11), R ３１ and R ４１ are each independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and a cycloalkyl group having 3 to 20 carbon atoms.

[0093] Examples of alkyl groups having 1 to 20 carbon atoms include straight-chain or branched-chain alkyl groups such as methyl, ethyl, n-propyl, i-propyl, s-butyl, t-butyl, isopentyl, neopentyl, t-pentyl, t-hexyl, and 1,1,2-trimethylpropyl. Among these, alkyl groups having 3 to 20 carbon atoms are preferred, those having 4 to 20 carbon atoms are more preferred, and those having 4 to 10 carbon atoms are particularly preferred. Furthermore, alkyl groups in which the carbon atom bonded to the aromatic ring is tertiary are preferred, and examples thereof include t-butyl, t-pentyl, and t-hexyl.

[0094] Examples of cycloalkyl groups having 3 to 20 carbon atoms include a cyclohexyl group, a cyclooctyl group, an adamantyl group, etc. Among these, a cycloalkyl group having 6 to 14 carbon atoms is preferred, and a cycloalkyl group having 6 to 10 carbon atoms is more preferred.

[0095] R ３１ and R ４１ As R, a tertiary alkyl group having 4 to 20 carbon atoms is preferred, a tertiary alkyl group having 4 to 7 carbon atoms is more preferred, and a t-butyl group is particularly preferred. ３１ and R ４１ may be the same or different.

[0096] R ３１ and R ４１ If R is a t-butyl group, the bulkiness of the t-butyl group will provide a sufficient stabilizing effect against hydrolysis of the compound represented by formula (11). ３１ and R ４１ is particularly preferably a t-butyl group.

[0097] R ３２ and R ４２each independently represents a group selected from the group consisting of a hydrogen atom, an alkyl group and an alkoxy group having 1 to 20 carbon atoms, a cycloalkyl group and a cycloalkoxy group having 3 to 20 carbon atoms, a dialkylamino group having 2 to 20 carbon atoms, an aryl group and an aryloxy group having 6 to 20 carbon atoms, an alkylaryl group, an alkylaryloxy group, an arylalkyl group and an arylalkoxy group having 7 to 20 carbon atoms, a cyano group, a hydroxy group, and a halogen atom.

[0098] Examples of alkyl groups having 1 to 20 carbon atoms include straight-chain or branched-chain alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, t-butyl, n-pentyl, isopentyl, neopentyl, t-pentyl, t-hexyl, etc. Examples of cycloalkyl groups having 3 to 20 carbon atoms include cyclohexyl, cyclooctyl, adamantyl, etc.

[0099] Examples of alkoxy groups having 1 to 20 carbon atoms include methoxy, ethoxy, isopropoxy, and t-butoxy groups. Among these, alkoxy groups having 1 to 12 carbon atoms are preferred. Examples of cycloalkoxy groups having 3 to 20 carbon atoms include cyclopentyloxy groups.

[0100] Examples of dialkylamino groups having 2 to 20 carbon atoms include dimethylamino and diethylamino groups. Examples of aryl groups having 6 to 20 carbon atoms include phenyl and naphthyl groups. Examples of aryloxy groups having 6 to 20 carbon atoms include phenoxy and naphthoxy groups. Examples of alkylaryl groups having 7 to 20 carbon atoms include p-tolyl and o-tolyl groups.

[0101] Examples of alkylaryloxy groups having 7 to 20 carbon atoms include 2,3-xylenoxy. Examples of arylalkyl groups having 7 to 20 carbon atoms include benzyl. Examples of arylalkoxy groups having 7 to 20 carbon atoms include 2-(2-naphthyl)ethoxy. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine.

[0102] R ３２ and R ４２ is preferably a hydrogen atom. A substituent at this position has little effect on improving the reactivity in the hydroformylation reaction or on stabilizing the compound represented by formula (11) itself. Therefore, from the viewpoint of reducing the production cost of the compound, a hydrogen atom, which is the simplest substituent, is preferred.

[0103] R ３３ and R ４３ are each independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an alkylaryl group and arylalkyl group having 7 to 20 carbon atoms.

[0104] Examples of alkyl groups having 1 to 20 carbon atoms include straight-chain or branched-chain alkyl groups such as methyl, ethyl, n-propyl, i-propyl, s-butyl, t-butyl, isopentyl, neopentyl, t-pentyl, and t-hexyl. Of these, alkyl groups having 4 to 20 carbon atoms are preferred, and alkyl groups having 4 to 10 carbon atoms are particularly preferred. Furthermore, alkyl groups in which the carbon atom bonded to the aromatic ring is tertiary are preferred, and examples thereof include t-butyl, t-pentyl, and t-hexyl.

[0105] Examples of cycloalkyl groups having 3 to 20 carbon atoms include a cyclohexyl group, a cyclooctyl group, and an adamantyl group. Among these, a cycloalkyl group having 6 to 14 carbon atoms is preferred, and a cycloalkyl group having 6 to 10 carbon atoms is more preferred. Examples of aryl groups having 6 to 20 carbon atoms include a phenyl group and a naphthyl group. Examples of alkylaryl groups having 7 to 20 carbon atoms include a p-tolyl group and an o-tolyl group. Examples of arylalkyl groups having 7 to 20 carbon atoms include a benzyl group.

[0106] R ３３ and R ４３ are each independently preferably a tertiary alkyl group having 4 to 20 carbon atoms, more preferably a tertiary alkyl group having 4 to 7 carbon atoms, and particularly preferably a t-butyl group.

[0107] R ３４ and R ４４ each independently represents a group selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, a silyl group, a siloxy group, and a halogen atom.

[0108] Examples of alkyl groups having 1 to 12 carbon atoms include straight-chain or branched-chain alkyl groups such as methyl, ethyl, n-propyl, isopropyl, t-butyl, and decyl. Examples of cycloalkyl groups having 3 to 12 carbon atoms include cyclopropyl and cyclohexyl. Examples of alkoxy groups having 1 to 12 carbon atoms include methoxy, ethoxy, and t-butoxy.

[0109] Examples of the silyl group include a trimethylsilyl group, etc. Examples of the siloxy group include a silyl group and a trimethylsiloxy group, etc. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, etc.

[0110] Of these, R ３４ and R ４４ are each independently preferably an alkyl group having 1 to 3 carbon atoms such as a methyl group or an ethyl group, an alkoxy group having 1 to 3 carbon atoms such as a methoxy group or an ethoxy group, or a halogen atom, more preferably an alkyl group having 1 to 3 carbon atoms, and R ３４ and R ４４ is particularly preferably a methyl group.

[0111] R ３４ and R ４４ As the alkyl group, a small group such as an alkyl group having 1 to 3 carbon atoms, particularly a methyl group, is preferred, because it allows the hydroformylation reaction to proceed smoothly and improves the stability of the compound represented by formula (11).

[0112] Z １ ~Z ４ are each independently an aryl group having 6 to 20 carbon atoms. The aryl group may have a substituent. １ and Z ２ and Z ３ and Z ４ None of them are bonded to each other.

[0113] In particular, Z １ ~Z ４ is preferably one that does not have a substituent on the aromatic ring carbon atom adjacent to the carbon atom bonded to the oxygen atom, or one that has a substituent on the aromatic ring carbon atom but has 0 to 2 carbon atoms.

[0114] Z １ ~Z ４ has a substituent on an aromatic ring carbon atom adjacent to the carbon atom bonded to the oxygen atom, the substituent is preferably selected from the group consisting of groups having 1 to 2 carbon atoms, such as a methyl group and an ethyl group, a trifluoromethyl group, a cyano group, a nitro group, and a halogen atom, such as a chlorine atom and a fluorine atom.

[0115] Z １ ~Z ４When Z has a substituent at a position other than the aromatic ring carbon atom, the substituent includes a linear or branched alkyl group having 1 to 12, preferably 1 to 8, carbon atoms, such as a methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, s-butyl group, t-butyl group, n-pentyl group, isopentyl group, neopentyl group, or t-pentyl group; an alkoxy group having 1 to 12, preferably 1 to 8, carbon atoms, such as a methoxy group or ethoxy group; and an aryl group having 6 to 18, preferably 6 to 10, carbon atoms, such as a phenyl group or naphthyl group. Other examples of the substituent include a halogen atom, a cyano group, a nitro group, a trifluoromethyl group, a hydroxyl group, an amino group, an acyl group, a carbonyloxy group, an oxycarbonyl group, an amido group, a sulfonyl group, a sulfinyl group, a silyl group, and a thionyl group. １ ~Z ４ may each have 1 to 5 of these substituents.

[0116] Z １ ~Z ４ Preferable examples of the alkyl group include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a p-trifluoromethylphenyl group, a 2-ethylphenyl group, a 2-methylphenyl group, a 3-methylphenyl group, a 4-methylphenyl group, a 2,3-dimethylphenyl group, a 2,4-dimethylphenyl group, a 2,5-dimethylphenyl group, a 3,4-dimethylphenyl group, a 3,5-dimethylphenyl group, a 2-chlorophenyl group, a 3-chlorophenyl group, a 4-chlorophenyl group, a 2,3-dichlorophenyl group, a 2,4-dichlorophenyl group, a 2,5-dichlorophenyl group, a 3,4-dichlorophenyl group, a Examples thereof include a chlorophenyl group, a 3,5-dichlorophenyl group, a 2-methoxyphenyl group, a 3-methoxyphenyl group, a 4-methoxyphenyl group, a 2,3-dimethoxyphenyl group, a 3,4-dimethoxyphenyl group, a 3,5-dimethoxyphenyl group, a 4-cyanophenyl group, a 4-nitrophenyl group, a 4-phenylphenyl group, a 5,6,7,8-tetrahydro-1-naphthyl group, a 5,6,7,8-tetrahydro-2-naphthyl group, a 2-methyl-1-naphthyl group, a 4-chloro-1-naphthyl group, a 2-nitro-1-naphthyl group, and a 7-methoxy-2-naphthyl group.

[0117] Of these, a 1-naphthyl group or a 2-naphthyl group is preferred from the viewpoints of improving the thermal stability of the ligand and improving the selectivity for the production of straight-chain aldehydes when producing aldehydes by hydroformylation reaction.

[0118] The bisphosphite compound represented by formula (11) includes R ３１ and R ４１ are each independently a tertiary alkyl group having 4 to 20 carbon atoms; R ３２ and R ４２ is a hydrogen atom, and R ３３ and R ４３ are each independently a tertiary alkyl group having 4 to 20 carbon atoms, and R ３４ and R ４４ are each independently selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, and a halogen atom. １ ~Z ４ each independently has no substituent on the aromatic ring carbon atom adjacent to the carbon atom bonded to the oxygen atom, or has a substituent having 1 to 2 carbon atoms on the aromatic ring carbon atom; and Z １ ~Z ４ Preferred are bisphosphite compounds in which none of the groups are bonded to each other.

[0119] Further, the bisphosphite compound represented by formula (11) is ３１ , R ４１ , R ３３ and R ４３ are each independently a tertiary alkyl group having 4 to 7 carbon atoms; R ３２ and R ４２ is a hydrogen atom, and R ３４ and R ４４ However, bisphosphite compounds in which each independently represents an alkyl group having 1 to 3 carbon atoms are more preferred. １ ~Z ４ are each independently a 1-naphthyl group or a 2-naphthyl group, and R ３１ , R４１ , R ３３ and R ４３ is a t-butyl group, and R ３４ and R ４４ Particularly preferred are bisphosphite compounds in which is a methyl group.

[0120] Examples of the bisphosphite compound represented by the above formula (11) are shown below. The symbols in the following formulas have the following meanings.

[0121]

[0122]

[0123]

[0124]

[0125]

[0126]

[0127]

[0128]

[0129]

[0130]

[0131]

[0132]

[0133]

[0134]

[0135]

[0136] The bisphosphite compound represented by formula (11) can be produced by the method described in WO 2019 / 039565.

[0137] These organic phosphorus ligand compounds may be used alone or in combination of two or more, but usually only one is used.

[0138] The organophosphorus ligand compound is not particularly limited, but from the viewpoint of providing a catalyst with excellent reaction activity and thermal decomposition resistance in a hydroformylation reaction, a phosphite compound represented by the formula (10) or a bisphosphite compound represented by the formula (11) is preferred, and a bisphosphite compound represented by the formula (11) is particularly preferred. That is, the Group 8 to 10 metal-organophosphorus complex catalyst used in the present invention is preferably a Group 8 to 10 metal-phosphite complex catalyst.

[0139] The Group 8 to 10 metal-organic phosphorus complex catalyst can be easily prepared from a long-form Group 8 to 10 metal compound of the periodic table (hereinafter referred to as "Group 8 to 10 metal compound") and an organophosphorus ligand compound by a known complex formation method. The Group 8 to 10 metal compound and the organophosphorus ligand compound may be supplied to a reaction zone to form a complex within the reaction zone. In this case, the organophosphorus ligand compound may be introduced into the reaction zone as is, but considering ease of handling, it is preferable to introduce it after dissolving it in the reaction medium.

[0140] Examples of Group 8 to 10 metal compounds include water-soluble inorganic salts or inorganic complex compounds such as rhodium chloride, palladium chloride, ruthenium chloride, platinum chloride, rhodium bromide, rhodium iodide, rhodium sulfate, rhodium nitrate, palladium nitrate, ammonium rhodium chloride, and sodium rhodium chloride; and water-soluble organic acid salts such as rhodium formate, rhodium acetate, palladium acetate, rhodium propionate, palladium propionate, and rhodium octanoate. Complex species of the respective metals may also be used. Among these, rhodium acetate is preferred from the viewpoints of excellent reaction activity and catalyst cost.

[0141] [Hydroformylation Reaction Step] The hydroformylation reaction is carried out by reacting an olefin with hydrogen and carbon monoxide in the presence of a catalyst such as a Group 8 to 10 metal-organic phosphorus complex catalyst. The olefin is not particularly limited, but examples thereof include olefins having 2 to 20 carbon atoms. Examples of olefins having 2 to 20 carbon atoms include α-olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, and 1-octene, and internal olefins such as 2-butene, 2-pentene, 3-hexene, and 4-octene.

[0142] The reaction medium for the hydroformylation reaction is preferably a solvent that dissolves the raw material olefin and the catalyst, such as a Group 8 to 10 metal-organic phosphorus complex catalyst, and has a boiling point higher than that of the aldehyde produced and does not inhibit the reaction. Examples of solvents that can be used in the hydroformylation reaction include aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as hexane and octane; esters such as butyl acetate and butyl butyrate; and ketones.

[0143] The concentration of the catalyst in the reaction medium is usually 1 ppm by mass to 10% by mass in terms of metal atoms of Groups 8 to 10 metals, etc., and an excess amount of an organophosphorus ligand compound such as a phosphite compound used as a ligand is usually present in the reaction medium in order to increase the stability of the complex catalyst, etc.

[0144] The hydroformylation reaction can be carried out under known conditions. For example, when using a Group 8 to 10 metal-organic phosphorus complex catalyst, particularly a rhodium-phosphite complex catalyst, the reaction conditions are generally selected appropriately within the following ranges: Hydrogen partial pressure: 0.01 to 20 MPaG Carbon monoxide partial pressure: 0.01 to 20 MPaG Total pressure: 0.02 MPaG to 30 MPaG Hydrogen partial pressure / carbon monoxide partial pressure: 0.1 to 10 Reaction temperature: 60 to 200°C Rh (rhodium) concentration: several ppm by mass to several % by mass P (free organophosphorus ligand) / Rh: 2 to 10,000 (molar ratio) Reaction time: several minutes to several tens of hours

[0145] In the hydroformylation reaction, an aldehyde having a carbon number of n+1 can be obtained from a raw material olefin having a carbon number of n (n is an integer of, for example, 2 to 20). Examples of such aldehydes include propionaldehyde, butylaldehyde, pentylaldehyde, hexylaldehyde, heptylaldehyde, octylaldehyde, nonylaldehyde, and decylaldehyde. Usually, the aldehyde is obtained as a mixture of linear and branched aldehydes.

[0146] The hydroformylation reaction is usually carried out under the above reaction conditions using a flow reactor, but a batch reactor can also be used.

[0147] The main types of flow reaction (reaction using the above-mentioned flow reactor) are the stripping method and the liquid circulation method.

[0148] The stripping method is a method in which a reaction liquid containing a catalyst is held in a reactor, an olefin and an oxo gas are continuously fed, and the aldehyde produced by the reaction is vaporized in the reactor and removed from the system.

[0149] The liquid circulation system is a method in which a reaction medium containing an olefin, an oxo gas, and a catalyst is continuously supplied to a reactor, and a reaction liquid containing the produced aldehyde, the catalyst, the reaction medium, etc. is continuously withdrawn from the reactor. The reaction liquid withdrawn from the reactor is separated into the produced aldehyde and the reaction liquid containing the catalyst by a separation operation such as stripping with unreacted gas or distillation. The resulting produced aldehyde is withdrawn from the system, and the reaction liquid containing the catalyst (in the present invention, this reaction liquid corresponds to the reaction liquid withdrawn in the reaction liquid withdrawal step) is returned to the reactor and recycled, usually after high-boiling by-products in the reaction liquid are removed using a known separation operation such as distillation. In the present invention, the stickiness of the resulting aggregate can be controlled by adjusting the content of high-boiling by-products in the reaction liquid in the aggregation step described below.

[0150] In the stripping method, high-boiling by-products, which are by-products of the hydroformylation reaction, accumulate in the catalyst-containing reaction liquid retained in the reactor. Therefore, typically, a portion of the reaction liquid containing the high-boiling by-products and the catalyst (in the present invention, this reaction liquid corresponds to the reaction liquid withdrawn in the reaction liquid withdrawal step) is intermittently withdrawn outside the reaction zone. In the liquid circulation method, if the catalyst-containing reaction liquid is continuously recycled, high-boiling by-products, which are by-products, accumulate in the reaction zone. Therefore, a portion of the reaction liquid containing the high-boiling by-products and the catalyst (in the present invention, this reaction liquid corresponds to the reaction liquid withdrawn in the reaction liquid withdrawal step) is withdrawn continuously or intermittently outside the reaction zone. The amount of the reaction zone, i.e., the amount of the reaction liquid withdrawn from the reactor, may be appropriately determined depending on the amount of high-boiling by-products produced.

[0151] Usually, when a reaction solution is withdrawn from the reaction zone, a new catalyst is supplied to the reaction zone in an amount corresponding to the amount of catalyst contained in the withdrawn reaction solution. In the present invention, the withdrawn reaction solution is subjected to a coagulation step and then returned to the reaction zone, thereby reducing the amount of catalyst to be newly supplied. In particular, for Group 8 to 10 metals, the reaction can be maintained with almost no replenishment.

[0152] The high-boiling by-products are composed of a wide variety of complex components, but are primarily aldehyde condensates formed by condensation of the aldehyde, the target product of the hydroformylation reaction, and have a higher boiling point than the aldehyde produced, making them high-boiling substances that cannot be removed simply by distilling the aldehyde. Specific examples of such high-boiling by-products include aldols, which are dimers of the aldehyde produced, ester compounds, which are dimers of the aldehyde produced by the Tishchenko reaction of the aldehyde produced, unsaturated aldehydes, which are dehydration products of the aldols, saturated aldehydes and saturated alcohols, which are hydrogenation products of the unsaturated aldehydes, unsaturated ethers, which are dehydration products of hemiacetals obtained by reacting the aldehyde produced with its hydrogenated alcohol, acetals obtained by reacting the hemiacetals with the aldehyde produced, and trimers of the aldehyde produced.

[0153] When a Group 8 to 10 metal-phosphite complex catalyst is used as the catalyst, the reaction liquid in which the high-boiling by-products have accumulated contains phosphite, phosphonate produced by decomposition of the phosphite, phosphorous acid, and the like.

[0154] For example, when rhodium is used as the Group 8 to 10 metal, the reaction solution in which the high-boiling by-products have accumulated contains the following rhodium complexes (a) and (b): (a) A complex in which carbon monoxide and a bisphosphite represented by the formula (11) are coordinated with rhodium (Rh): for example, RhH(CO) ２ (b) Rhodium cluster complexes in which multiple rhodium atoms are bonded to each other and carbon monoxide and a bisphosphite represented by the formula (11) are coordinated to the rhodium atoms: for example, [Rh(CO)(bisphosphite)] ２ and [Rh(CO) ２ (bisphosphite)] ２ Although the above description has been given using rhodium as an example, the same applies to other metals in Groups 8 to 10.

[0155] [Reaction Liquid Withdrawal Step] The reaction liquid withdrawal step is a step of withdrawing part or all of the reaction liquid in which high-boiling by-products have accumulated from the hydroformylation reaction zone. Specifically, this is a step of withdrawing the reaction liquid containing the aldehyde produced by the hydroformylation reaction, the catalyst, the reaction medium, etc., from the reactor while the hydroformylation reaction as described above is being carried out.

[0156] The reaction liquid in the hydroformylation reaction zone contains about 40 to 80 mass% of high-boiling by-products. A poor solvent for the catalyst is added to and mixed with the reaction liquid containing the high-boiling by-products in an agglomeration step to crystallize an agglomerate containing the catalyst and the high-boiling by-products. This eliminates catalyst loss during filtration and allows the catalyst to be recovered at a high recovery rate, compared to the methods disclosed in Patent Documents 1 to 4, in which crystallization is performed in a state where high-boiling by-products are removed as much as possible, and the precipitated crystals are then filtered to separate the catalyst crystals from the crystallization mother liquor.

[0157] In the reaction liquid withdrawing step, the hydroformylation reaction liquid withdrawn from the hydroformylation reaction zone may be fed to the coagulation step after removing light boiling components therefrom, as required. To remove the light boiling components from the reaction liquid, known separation procedures such as distillation can be used.

[0158] When a rhodium-phosphite complex catalyst is used as the catalyst, the reaction liquid extracted in the reaction liquid extraction step, i.e., the reaction liquid before the aggregation treatment, usually has the following composition, and this reaction liquid is subjected to the next aggregation step.

[0159] (Composition of the reaction solution withdrawn in the reaction solution withdrawal step) Rhodium atoms in the complex catalyst: 50 to 2000 ppm by mass Phosphite compound: 1000 ppm by mass to 3% by mass n-aldehyde: 1 to 30% by mass Other components (various complexes, high-boiling by-products, etc.): 40 to 80% by mass

[0160] The "various complexes" contained in the "other components" refer to the various rhodium complexes contained in the reaction liquid in which high-boiling by-products have accumulated, as described above in the section [Hydroformylation Reaction Step].

[0161] [Aggregation Step] In the aggregation step, a poor solvent for the catalyst (hereinafter, sometimes simply referred to as "poor solvent") is added to and mixed with the reaction liquid extracted in the reaction liquid extraction step to precipitate aggregates containing the catalyst and high-boiling by-products.

[0162] Specifically, the extracted reaction liquid and poor solvent are charged into a mixing tank to precipitate the aggregates.

[0163] The poor solvent is one in which the solubility of the Group 8 to 10 metal compound is lower than that of the reaction liquid. The poor solvent is preferably one that maintains a homogeneous phase with the reaction liquid and does not participate in the reaction in the reaction zone.

[0164] Specific examples of poor solvents include methanol, ethanol, propanol (n-, i-), butanol (n-, i-, t-), acetone, and mixtures thereof with water. From the viewpoint of the recovery rate of the Group 8 to 10 metal-phosphite complex catalyst, a mixture of water and an alcohol is preferred, and a mixture of water and an alcohol having 1 to 3 carbon atoms is particularly preferred. The water content in this mixture is preferably 12 to 40 mass%, more preferably 13 to 25 mass%, and even more preferably 15 to 22 mass%, relative to 100 mass% of the mixture. If the water content is equal to or greater than the lower limit, the recovery rate of the complex catalyst increases due to the solubility of the complex. If the water content is equal to or less than the upper limit, the reaction solution is likely to become a homogeneous phase, and the recovery rate of the complex catalyst can be maintained at a good level.

[0165] The mixing ratio (mass ratio) of the poor solvent to the reaction solution varies depending on the type of poor solvent and the composition of the reaction solution, but is preferably 5:1 to 15:1, more preferably 6:1 to 10:1, and even more preferably 7:1 to 9:1. If the ratio of the poor solvent is below the upper limit, the amount of complex catalyst dissolved in the poor solvent decreases, increasing the catalyst recovery rate and allowing the size of the aggregate recovery device to be reduced. If the ratio of the poor solvent is above the lower limit, the reaction solution is likely to become a homogeneous phase, allowing the complex catalyst recovery rate to be maintained at a good level.

[0166] The withdrawn reaction liquid may be mixed with a poor solvent as it is, or may be mixed with a poor solvent after at least a part of the reaction medium is removed by distillation or the like.

[0167] The reaction mixture and the poor solvent are preferably mixed under stirring.

[0168] The temperature in the aggregation step is preferably 0 to 70°C, more preferably 0 to 40°C, and even more preferably 5 to 20°C. If the temperature during aggregation is equal to or lower than the upper limit, the catalyst recovery rate is excellent. If the temperature during aggregation is equal to or higher than the lower limit, the poor solvent can be kept in a liquid state, and cooling energy can be reduced.

[0169] The aggregation time is not particularly limited, but is usually 10 minutes to 10 hours, and more preferably 30 minutes to 5 hours.

[0170] The aggregation step is preferably carried out in an inert gas atmosphere such as nitrogen gas or argon gas, from the viewpoint of preventing the complex catalyst contained in the reaction solution and the aggregate from being oxidized and deactivated.

[0171] The aggregation step is preferably carried out by stirring the reaction solution and poor solvent under neutral to acidic conditions, since this eliminates the need for operations such as washing and neutralization when the liquid containing the aggregates after aggregation is supplied to the hydroformylation reaction zone. Usually, the reaction solution withdrawn from the hydroformylation reaction zone is weakly acidic, and a liquid obtained by mixing this reaction solution with a poor solvent consisting of a mixture of water and alcohol has a pH of about 4 to 7. Therefore, the aggregation operation can be carried out directly without any particular pH adjustment.

[0172] In this manner, the reaction solution and the poor solvent are stirred in an inert gas atmosphere at the above-mentioned suitable temperature range for a predetermined time, thereby precipitating an aggregate. For this reason, it is preferable to use a sealable glass container, a stainless steel container, an SUS container, or the like equipped with a stirrer as the mixing tank used in the aggregation step.

[0173] The aggregates that precipitate when the poor solvent is mixed with the reaction liquid withdrawn from the hydroformylation reaction zone are sticky under the aggregation conditions. Here, "sticky" means that the precipitated aggregates have sufficient adhesive strength to adhere to the inner surface of the mixing vessel in the aggregation step of the present invention. Because the aggregates are sticky, the precipitated aggregates are separated from the liquid in the mixing vessel and, due to their adhesiveness, adhere to the inner surfaces of the mixing vessel, i.e., the bottom and inner walls of the mixing vessel, the stirring blades, etc.

[0174] In other words, in the present invention, the reaction solution containing high-boiling by-products is extracted from the hydroformylation reaction zone and subjected to coagulation, and the coagulates precipitated by the coagulation contain the high-boiling by-products as well as the complex catalyst, and the presence of the high-boiling by-products makes the coagulates sticky. Furthermore, by incorporating the complex catalyst into such sticky coagulates, the complex catalyst can be recovered at a high recovery rate.

[0175] In the production method of the present invention, in order to increase the recovery rate of the complex catalyst by precipitating such sticky aggregates and adhering the precipitated aggregates to the inner surface of the mixing vessel and recovering them, it is preferable to carry out the aggregation under conditions such that high-boiling by-products are distributed in a certain proportion in the aggregates. Specifically, when the total mass of high-boiling by-products contained in the reaction liquid withdrawn from the hydroformylation reaction zone is taken as 100 mass%, the lower limit of the distribution proportion of high-boiling by-products in the aggregates is preferably 4.0 mass% or more, more preferably 5.0 mass% or more, and even more preferably 6.0 mass% or more. On the other hand, if the distribution proportion of high-boiling by-products in the aggregates is excessively high, the yield of the aggregates will decrease. Therefore, it is preferable to carry out the aggregation so that the upper limit of the distribution proportion of high-boiling by-products in the aggregates is usually 30 mass% or less, more preferably 20 mass% or less, and even more preferably 10 mass% or less. The above upper and lower limits can be combined in any manner. That is, the distribution ratio of high-boiling by-products in the coagulate is preferably 4.0% by mass or more and 30% by mass or less, more preferably 5.0% by mass or more and 20% by mass or less, and even more preferably 6.0% by mass or more and 10% by mass or less, when the total mass of high-boiling by-products contained in the reaction liquid extracted from the hydroformylation reaction zone is taken as 100% by mass.

[0176] This distribution ratio can be controlled by adjusting aggregation conditions such as the composition of the poor solvent, the ratio of the poor solvent to the reaction solution, the aggregation temperature, etc. Details of the method for measuring the "distribution ratio" will be described later in the Examples section.

[0177] [Recovery Step] In the recovery step, the aggregates that have precipitated in the aggregation step and adhered to the inner surface of the mixing vessel are recovered. The recovered aggregates are preferably supplied to the hydroformylation reaction zone.

[0178] Although there are no particular limitations on the method for recovering the aggregates, it is preferable to recover the aggregates by dissolving them in a good solvent for the complex catalyst in the aggregates, as this is an easy operation and can increase the recovery rate of the complex catalyst. Specifically, the liquid in the mixing tank is removed to leave only the aggregates, and a good solvent for the complex catalyst is added to dissolve the aggregates.

[0179] The good solvent for the complex catalyst used in this case is not particularly limited. As the good solvent, those previously described as the reaction medium for the hydroformylation reaction or the aldehyde product obtained by the hydroformylation reaction are preferred, since the aggregate solution can be fed as is to the hydroformylation reaction zone.

[0180] Specific examples of good solvents include, when the raw material olefin is propylene, aldehydes such as n-butylaldehyde and i-butylaldehyde, and aromatic hydrocarbons such as benzene, toluene, and xylene.

[0181] The amount of the good solvent used to dissolve the agglomerates is not particularly limited, and a smaller amount that dissolves the agglomerates is preferred from the viewpoint of being able to reduce the volume of the mixing vessel. The amount of the good solvent varies depending on the solubility of the catalyst in the good solvent used and the content of high-boiling-point compounds in the agglomerates, but is usually preferably about 5 to 100 times by mass the amount of the agglomerates.

[0182] The temperature condition when dissolving the aggregates in the good solvent is preferably about 5 to 60°C.

[0183] The solution of the coagulates can be supplied to the hydroformylation reaction zone as it is, but if necessary, unnecessary components may be removed by a known separation procedure such as distillation, or a solvent or a complex catalyst having high catalytic activity may be added, and then the solution may be supplied to the hydroformylation reaction zone.

[0184] In the present invention, the reaction solution containing the complex catalyst and high-boiling by-products is withdrawn from the hydroformylation reaction zone, and a poor solvent is added and mixed in a mixing vessel to precipitate sticky aggregates containing the complex catalyst and high-boiling by-products. The precipitated aggregates adhere to the inner surface of the mixing vessel and are recovered. By using this method, compared to conventional crystallization methods in which the complex catalyst is precipitated as non-sticky crystals while removing as much high-boiling by-products as possible, and a slurry in which the crystallized product is uniformly dispersed in the mother liquor is obtained, the production method of the present invention eliminates loss of the complex catalyst due to operations such as filtration of the slurry, and allows the complex catalyst to be recovered and reused at a high recovery rate. Therefore, the production method of the present invention can avoid waste of expensive Group 8 to 10 metals, such as rhodium, in the complex catalyst, thereby improving productivity.

[0185] 2. Alcohol Production Method The alcohol production method of the present invention uses an aldehyde produced by the aldehyde production method of the present invention. Alcohol can be produced by reacting the aldehyde with hydrogen directly, i.e., by subjecting it to a hydrogenation reaction, or by subjecting it to a hydrogenation reaction after dimerization. For the hydrogenation reaction, a known solid catalyst in which a metal such as nickel, chromium, or copper is supported on a carrier can be used. The reaction conditions are typically a temperature of 60 to 200°C and a hydrogen pressure of about 0.1 to 20 MPaG.

[0186] 3. Catalyst Composition The catalyst composition of the present invention is a catalyst composition comprising a catalyst and high-boiling by-products, wherein the catalyst is a long-form metal-organophosphorus complex catalyst selected from Groups 8 to 10 of the Periodic Table, and the content of the high-boiling by-products is 30 mass% or more relative to 100% of the total mass of the catalyst composition.

[0187] The catalyst composition of the present invention, which satisfies the above-mentioned constitution, becomes sticky, and by adhering the catalyst composition to the inner surface of a reaction apparatus such as a mixing tank and recovering the catalyst, the recovery rate of the catalyst can be improved.

[0188] The method for obtaining the catalyst composition of the present invention is not particularly limited, and examples thereof include a method for obtaining the catalyst composition as an aggregate in any one of the first, second, and third embodiments of the aldehyde production method of the present invention described above.

[0189] In the catalyst composition of the present invention, the catalyst can be the same as the catalyst used in the first, second, and third embodiments of the method for producing an aldehyde of the present invention. In the catalyst composition of the present invention, the high-boiling by-product can be the same as the high-boiling by-product listed in the first, second, and third embodiments of the method for producing an aldehyde of the present invention.

[0190] In the catalyst composition of the present invention, the long-form metal-organophosphorus complex catalyst selected from Groups 8 to 10 of the Periodic Table can be the same as the long-form metal-organophosphorus complex catalyst selected from Groups 8 to 10 of the Periodic Table listed in the first, second, and third embodiments of the method for producing an aldehyde of the present invention.

[0191] In the catalyst composition of the present invention, the lower limit of the content of the high-boiling by-products is 30% by mass or more, preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and particularly preferably 70% by mass or more, relative to the total mass of the catalyst composition (100%), from the viewpoint that the catalyst composition becomes sticky and can be recovered by adhering the catalyst composition to the inner surface of a reaction apparatus such as a mixing tank, thereby increasing the recovery rate of the catalyst such as the complex catalyst. On the other hand, the upper limit of the content of the high-boiling by-products is not particularly limited, and can also be set to preferably 97% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less, relative to the total mass of the catalyst composition (100%), from the viewpoint that the catalyst composition is likely to precipitate as aggregates.

[0192] In the catalyst composition of the present invention, the lower limit of the catalyst content is not particularly limited, and from the viewpoint of the catalyst composition easily precipitating as aggregates, it can be preferably 3% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, relative to the total mass (100%) of the catalyst composition. On the other hand, from the viewpoint of the catalyst composition becoming sticky and being able to adhere the catalyst composition to the inner surface of a reaction apparatus such as a mixing tank and recover it, thereby increasing the recovery rate of the catalyst such as the complex catalyst, the upper limit of the catalyst content is preferably 70% by mass or less, more preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, and particularly preferably 30% by mass or less, relative to the total mass (100%) of the catalyst composition.

[0193] In addition to the high-boiling by-products and catalyst, the catalyst composition of the present invention may contain other components such as a reaction solvent and an aldehyde which is the target product of the hydroformylation reaction in an amount of 10% by mass or less, preferably 5% by mass or less, relative to 100% by mass of the total mass of the catalyst composition.

[0194] 4. Method for Producing Aldehyde The method for producing an aldehyde of the present invention comprises dissolving the above-described catalyst composition of the present invention in a good solvent for the catalyst to obtain a catalyst solution, and subjecting an olefin to a hydroformylation reaction in the presence of the catalyst solution to obtain an aldehyde corresponding to the olefin.

[0195] The method for dissolving the catalyst composition of the present invention in a good solvent for the catalyst to obtain a catalyst solution is not particularly limited, and for example, the same method and conditions as those for obtaining an aggregate solution using the catalyst composition of the present invention instead of an aggregate in the recovery step of any of the first, second, and third embodiments of the aldehyde production method of the present invention described above can be adopted.

[0196] Furthermore, the method for hydroformylating an olefin in the presence of the catalyst solution to obtain an aldehyde corresponding to the olefin is not particularly limited, and for example, the same conditions as those exemplified in the hydroformylation reaction step in any one of the first, second, and third embodiments of the above-mentioned method for producing an aldehyde of the present invention can be employed.

[0197] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention.

[0198] The compounds used in the examples and comparative examples are as follows: Aqueous rhodium acetate solution (rhodium acetate concentration 28% by mass) (trade name: Rhodium Acetate L, manufactured by N.E. Chemcat Corporation) n-Butyl aldehyde (purity 99% or higher, manufactured by Mitsubishi Chemical Corporation) Methanol (trade name: Reagent Grade Methanol, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) Demineralized water (manufactured by Mitsubishi Chemical Corporation)

[0199] Phosphite Ligand A (bisphosphite ligand compound shown below, synthesized by the method described in WO 2019 / 039565)

[0200] (1,5-cyclooctadiene)acetate rhodium dimer (trade name: Rh ２ (cod) ２ (OAc) ２ , manufactured by N.E. Chemcat Corporation)

[0201] Example 1 A hydroformylation reaction of propylene was carried out using rhodium acetate as the long-form Group 8 to 10 metal compound of the periodic table and phosphite ligand A as the organophosphorus ligand. The reaction solution was then extracted from the hydroformylation reaction zone, and low-boiling components were removed by distillation. The composition of the reaction solution after distillation and before being subjected to a coagulation treatment was as follows. The amount of rhodium atoms in the complex catalyst in the reaction solution was quantified by X-ray fluorescence analysis. The amount of n-butylaldehyde was quantified by gas chromatography-internal standard method. The amount of phosphite ligand A was quantified by high-performance liquid chromatography-external standard method.

[0202] (Composition of reaction solution before aggregation treatment) Rhodium atoms in complex catalyst: 373 ppm by mass Phosphite ligand A: 12,006 ppm by mass n-butylaldehyde: 10.6% by mass Other components (various complexes, high-boiling by-products, etc.): 88.2% by mass

[0203] A 0.5 L glass vessel equipped with an electromagnetic induction stirrer was used as the mixing vessel. The extracted reaction solution and a mixed solvent of methanol and water (methanol:water = 80:20 (mass ratio)) as a poor solvent were added to the mixing vessel in an inert gas (nitrogen gas) atmosphere so that the mass ratio of poor solvent to reaction solution was 9.00. After sealing the mixing vessel, the mixture was stirred at 500 rpm and maintained at 10°C for 2 hours to carry out an aggregation treatment, resulting in the precipitation of a rhodium complex together with high-boiling by-products.

[0204] (Mold of flocculation treatment liquid and properties of flocculants) When the flocculation treatment liquid was visually observed, it was found that the precipitated flocculants adhered to the inner wall of the mixing tank, the stirring blades, etc., and the flocculants and the mother liquor were separated into solid and liquid. Furthermore, the adhered flocculants had the properties of a sticky substance.

[0205] (Distribution ratio of high-boiling by-products in the aggregates) Thereafter, the mother liquor was removed from the mixing vessel, and 400 mL of n-butylaldehyde was added to the mixing vessel to dissolve the aggregates adhering to the inside of the mixing vessel at room temperature, and an aggregate-dissolved liquid was recovered. The content M1 (unit: mg) of high-boiling by-products contained in the aggregate-dissolved liquid and the content M2 (unit: mg) of high-boiling by-products contained in the mother liquor removed from the mixing vessel were measured by gas chromatography-internal standard method, and the distribution ratio of high-boiling by-products in the aggregates was calculated using the following formula. As a result, the distribution ratio was 9.2% by mass. Distribution ratio of high-boiling by-products (mass%) = M1 / (M1 + M2) × 100

[0206] (Rhodium Recovery Rate) The rhodium recovery rate was measured as the recovery rate of the complex catalyst according to the following procedure. The amount R1 (in terms of rhodium atoms, unit: mg) of the rhodium complex catalyst contained in the aggregate solution and the amount R2 (in terms of rhodium atoms, unit: mg) of the rhodium complex catalyst contained in the mother liquor extracted from the mixing tank were measured by X-ray fluorescence analysis, and the rhodium recovery rate (in terms of rhodium atoms, mass %) was calculated using the following formula. As a result, the recovery rate was 96.6 mass %. Rhodium recovery rate (mass %) = R1 / (R1 + R2) × 100

[0207] (Production of Aldehyde) The aggregate solution and toluene as a solvent were mixed, and 54 ml of the resulting mixture was placed in a 0.2 L up-and-down stirring autoclave under a nitrogen atmosphere, and the autoclave was sealed. The composition of the reaction solution before the hydroformylation reaction was as follows:

[0208] (Composition of reaction solution before hydroformylation reaction) Rhodium atoms in complex catalyst 152 ppm by mass Phosphite ligand A 5929 ppm by mass Toluene 45.0% by mass Other components (various complexes, high-boiling by-products, etc.) 54.4% by mass

[0209] Next, 3.6 g of propylene was fed into the autoclave, and the temperature was raised to 70°C. A mixed gas of hydrogen and carbon monoxide (hydrogen:carbon monoxide = 1:1 (volume ratio)) was then injected into the autoclave so that the total pressure in the autoclave was 1.0 MPaA. While maintaining this pressure and temperature, the hydroformylation reaction was carried out for 2 hours. During the propylene hydroformylation reaction, the propylene conversion, propane selectivity, aldehyde selectivity, N / I ratio of the target product butyraldehyde (ratio of n-butyraldehyde to i-butyraldehyde), propylene half-life, and the apparent reaction rate (rate constant) of the hydroformylation reaction calculated from the rate of decrease in carbon monoxide during the hydroformylation reaction were determined. The evaluation results are shown in Table 2.

[0210] Reference Example 1 In order to compare with the aldehyde production experiment of Example 1, an aldehyde production experiment was carried out using a commercially available rhodium catalyst according to the following procedure. The commercially available rhodium catalyst was (1,5-cyclooctadiene) acetate rhodium dimer (trade name: Rh ２ (cod) ２ (OAc) ２ , manufactured by N.E. Chemcat Corporation) was used. ２ (cod) ２ (OAc) ２ , bisphosphite ligand A, and toluene as a solvent were mixed, and 54 mL of the resulting mixture was placed in a 0.2 L up-and-down stirring autoclave under a nitrogen atmosphere, and the autoclave was sealed. The composition of the reaction mixture before the hydroformylation reaction is shown in Table 2.

[0211] Next, aldehyde was produced under the same conditions as in Example 1, except that the reaction conditions were as shown in Table 2. The evaluation results are shown in Table 2.

[0212] Examples 2 to 10 Aggregates containing a rhodium complex catalyst were obtained by carrying out the aggregation treatment under the same conditions as in Example 1, except that the composition of the reaction solution before the aggregation treatment or the composition of the poor solvent (water / methanol) was changed as shown in Table 1. Furthermore, aldehydes were produced using the obtained aggregates under the same conditions as in Example 1. The evaluation results are shown in Table 1.

[0213] 2(a) shows a photograph of the appearance of the mixing tank after aggregation obtained in Example 2. Visual observation revealed that aggregates had adhered to the inside of the mixing tank, and the reaction liquid after the reaction was in a state of solid-liquid separation.

[0214] Comparative Example 1 Crystallization was carried out under the same conditions as those of the aggregation treatment in Example 1, except that the composition of the reaction solution before the crystallization treatment and the composition of the poor solvent (water / methanol) were changed as shown in Table 1, to obtain a crystallized product containing a rhodium complex catalyst.

[0215] (Mold of crystallization treatment solution and properties of crystallized product) Figure 2(b) shows a photograph of the appearance of the mixing tank after crystallization treatment obtained in Comparative Example 1. Visual observation revealed that the crystallization treatment solution did not undergo solid-liquid separation and formed a uniform slurry. Furthermore, adhesion of the crystallized product to the inside of the mixing tank was not confirmed.

[0216] (Distribution ratio of high-boiling by-products in the crystallized product) The resulting slurry was then subjected to solid-liquid separation using a commercially available polytetrafluoroethylene membrane filter with a pore size of 0.5 μm. As in Example 1, the amount R1 (equivalent to rhodium atoms, units: mg) of rhodium complex catalyst contained in the solution of the crystallized product and the amount R2 (equivalent to rhodium atoms, units: mg) of rhodium complex catalyst in the recovered crystallized product were measured by fluorescent X-ray analysis, and the rhodium recovery rate was calculated using the following formula, which was 9.3 mass%. Rhodium recovery rate (mass%) = R1 / (R1 + R2) × 100

[0217] The relationship between the distribution ratio of high-boiling by-products and the rhodium recovery rate for the agglomerates of Examples 1 to 10 and the crystallized product of Comparative Example 1 is shown in FIG.

[0218]

[0219]

[0220] The above results reveal the following. In Examples 1 to 10, the aggregation conditions were controlled so that the distribution ratio of high-boiling by-products in the aggregates was significantly increased and sticky aggregates were precipitated. As a result, solid-liquid separation proceeded after the aggregation treatment, and almost all of the precipitated aggregates adhered to the inside of the mixing tank, specifically to the stirring blades and introduction tube in the glass container. Furthermore, by dissolving and recovering the deposits from the mixing tank, the rhodium complex catalyst could be recovered in high yield. The results shown in Table 2 demonstrate that the rhodium complex catalyst recovered in Example 1 had catalytic performance in aldehyde production equivalent to that of a complex catalyst using a commercially available rhodium-based catalyst.

[0221] On the other hand, in Comparative Example 1, the distribution ratio of high-boiling by-products in the crystallized product was low, so the obtained crystallized product was crystallized as non-sticky crystals. The crystallization treatment liquid was in the form of a uniform slurry. When the crystallized product was recovered by filtration, the recovery rate of the rhodium complex catalyst was low.

[0222] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on Japanese Patent Application No. 2021-202681, filed on December 14, 2021, and is incorporated by reference in its entirety.

Claims

1. A method for producing an aldehyde, comprising subjecting an olefin to hydroformylation reaction with a gas containing hydrogen and carbon monoxide in the presence of a catalyst, and mixing a part or all of the reaction solution withdrawn from the reaction zone with a poor solvent for the catalyst to precipitate an aggregate containing the catalyst and having adhesiveness.

2. The method for producing an aldehyde according to claim 1, wherein when the total mass of the high-boiling by-products contained in the reaction solution is 100% by mass, the distribution ratio of the high-boiling by-products contained in the aggregate is 4.0% by mass or more.

3. The method for producing an aldehyde according to claim 1 or 2, comprising mixing the poor solvent for the catalyst with a part or all of the reaction solution in a mixing tank, and causing the precipitated aggregate to adhere to the inner surface of the mixing tank or precipitate in an aggregated state in the mixing tank.

4. A method for producing an aldehyde, comprising subjecting an olefin to hydroformylation reaction with a gas containing hydrogen and carbon monoxide in the presence of a catalyst, and mixing a part or all of the reaction solution withdrawn from the reaction zone with a poor solvent for the catalyst to precipitate an aggregate containing the catalyst, wherein when the total mass of the high-boiling by-products contained in the reaction solution is 100% by mass, the distribution ratio of the high-boiling by-products into the aggregate is 4.0% by mass or more.

5. The method for producing an aldehyde according to claim 4, comprising mixing the poor solvent for the catalyst with a part or all of the reaction solution in a mixing tank, and causing the precipitated aggregate to adhere to the inner surface of the mixing tank or precipitate in an aggregated state in the mixing tank.

6. In a method for producing an aldehyde, comprising subjecting an olefin to hydroformylation reaction with a gas containing hydrogen and carbon monoxide in the presence of a catalyst, withdrawing a part or all of the reaction solution in which high-boiling by-products have accumulated from the reaction zone, mixing the withdrawn reaction solution with the poor solvent for the catalyst in a mixing tank to precipitate an aggregate containing the catalyst and the high-boiling by-products, and adhering and recovering the precipitated aggregate to the inner surface of the mixing tank.

7. The method for producing an aldehyde according to claim 6, wherein the aggregate has adhesiveness under the precipitation conditions.

8. The method for producing an aldehyde according to claim 6 or 7, wherein when the total mass of the high-boiling by-products contained in the extracted reaction solution is 100% by mass, the distribution ratio of the high-boiling by-products into the aggregate is 4.0% by mass or more.

9. The method for producing an aldehyde according to any one of claims 1 to 8, wherein the precipitated aggregate is supplied to the hydroformylation reaction zone.

10. The method for producing an aldehyde according to claim 9, wherein the precipitated aggregate is dissolved in a good solvent for the catalyst and supplied to the hydroformylation reaction zone.

11. The method for producing an aldehyde according to any one of claims 1 to 10, wherein the precipitation is carried out under neutral to acidic conditions.

12. The method for producing an aldehyde according to any one of claims 1 to 11, wherein the catalyst is a late transition metal group 8-10 metal-organophosphorus complex catalyst.

13. The method for producing an aldehyde according to claim 12, wherein the catalyst is a late transition metal group 8-10 metal-phosphite complex catalyst.

14. The method for producing an aldehyde according to claim 12 or 13, wherein the late transition metal group 8-10 metal is rhodium.

15. The method for producing an aldehyde according to any one of claims 1 to 14, wherein the poor solvent contains water and alcohol.

16. The method for producing an aldehyde according to claim 15, wherein the poor solvent is a mixture of water and alcohol, and the content ratio of water is 12 to 40% by mass based on 100% by mass of the total mass of the mixture.

17. The method for producing an aldehyde according to any one of claims 1 to 16, wherein the aggregate is precipitated under the condition of a temperature of 0 °C or higher and 70 °C or lower.

18. A method for producing an alcohol, comprising producing an aldehyde by the method according to any one of claims 1 to 17 and producing an alcohol from the aldehyde.

19. A catalyst composition containing a catalyst and a high-boiling by-product, wherein the catalyst is a late transition metal group 8-10 metal-organophosphorus complex catalyst, and the content ratio of the high-boiling by-product is 30% by mass or more based on 100% of the total mass of the catalyst composition.

20. The catalyst composition according to claim 19, wherein the catalyst composition has adhesiveness.

21. The catalyst composition according to claim 19 or 20, wherein the catalyst is a catalyst for producing an aldehyde by subjecting an olefin to a hydroformylation reaction.

22. The catalyst composition according to any one of claims 19 to 21, wherein the catalyst is a Group 8-10 metal-phosphite complex catalyst of the long-period type periodic table.

23. The catalyst composition according to any one of claims 19 to 22, wherein the Group 8-10 metal of the long-period type periodic table is rhodium.

24. A method for producing an aldehyde, comprising dissolving the catalyst composition according to any one of claims 19 to 23 in a good solvent for the catalyst to obtain a catalyst solution, and subjecting an olefin to a hydroformylation reaction in the presence of the catalyst solution.

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