Method for producing (poly)alkylene glycol monoalkyl ethers

Abstract

[Problem] To provide a method for producing a (poly)alkylene glycol monoalkyl ether, the method being capable of stably producing a (poly)alkylene glycol monoalkyl ether continuously from a starting material olefin without causing a decrease in the yield of the (poly)alkylene glycol monoalkyl ether or a decrease in the catalytic activity. [Solution] A method for producing a (poly)alkylene glycol monoalkyl ether, the method comprising a step for reacting an olefin and a (poly)alkylene glycol in the presence of a catalyst within a reactor, wherein: at least some of the starting materials used for the production is recovered and used again as the starting materials; at least one of the recovered starting materials contains an olefin; and the mass of branched olefins relative to the total mass of branched olefins and linear olefins contained in the recovered starting materials is controlled not to exceed 20% by mass.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a (poly)alkylene glycol monoalkyl ether. [Background technology]

[0002] BACKGROUND ART Methods for efficiently producing (poly)alkylene glycol monoalkyl ethers by reacting an olefin with a (poly)alkylene glycol in the presence of a catalyst have been known for some time.

[0003] For example, Patent Document 1 (JP-A-10-218819) discloses a production method in which, when (poly)alkylene glycol monoalkyl ethers are continuously produced by recycling unreacted raw materials, the catalytic activity decreases as the operating time increases, resulting in a decrease in the product yield. Therefore, in order to produce the product with high selectivity and high yield, a part of the catalyst is regenerated and reused as a catalyst.

[0004] Patent Document 2 (JP-A-10-168016) discloses a method for producing a (poly)alkylene glycol monoalkyl ether with high selectivity and high yield, by recovering a (poly)alkylene glycol dialkyl ether and / or alcohol produced as a by-product in the reaction of a (poly)alkylene glycol monoalkyl ether and supplying it to a reaction system, and reacting an olefin with the (poly)alkylene glycol in the presence of the recovered (poly)alkylene glycol dialkyl ether and / or alcohol. Summary of the Invention

[0005] Although conventional production methods can continuously produce (poly)alkylene glycol monoalkyl ethers, there remains a problem of a decrease in the hourly yield of (poly)alkylene glycol monoalkyl ether due to a long reaction time.

[0006] Therefore, an object of the present invention is to suppress a decrease in the hourly yield of a (poly)alkylene glycol monoalkyl ether when an olefin and a (poly)alkylene glycol are reacted in the presence of a catalyst to produce the (poly)alkylene glycol monoalkyl ether over a long period of time.

[0007] As a result of extensive research to solve the above problems, the present inventors have focused on branched olefins that are contained in trace amounts in the olefin raw material used and are also produced as by-products during the reaction. Since the equilibrium yield of the (poly)alkylene glycol monoalkyl ether obtained by the reaction using branched olefins contained in the reaction raw material is lower than that of linear olefins, when the unreacted raw material is recycled, the unreacted branched olefins accumulate in the reaction system over time.

[0008] A high concentration of this branched olefin causes a decrease in the yield of (poly)alkylene glycol monoalkyl ether, a decrease in productivity, and a decrease in catalytic activity. Therefore, the present inventors have discovered a method for stably producing (poly)alkylene glycol monoalkyl ether over a long period of time by removing at least a portion of the branched olefins in the recovered and used raw materials by a method such as distillation, and by keeping the amount of branched olefins in the reaction system at a specific amount or less, thereby completing the present invention.

[0009] That is, the present invention includes the following.

[0010] 1. A method for producing a (poly)alkylene glycol monoalkyl ether, which comprises reacting an olefin with a (poly)alkylene glycol in the presence of a catalyst in a reactor, recovering at least a portion of the raw materials used in the production and reusing them as raw materials, wherein at least one of the recovered raw materials contains an olefin, and controlling the mass of the branched olefin to the sum of the masses of the branched olefin and linear olefin contained in the recovered raw materials so as not to exceed 20 mass%.

[0011] 2. The method according to 1., wherein the olefin has 6 to 20 carbon atoms.

[0012] 3. The method according to 1. or 2., wherein the recovered raw material contains olefins from which branched olefins have been separated by distillation.

[0013] 4. The method according to any one of 1. to 3., wherein at least one of the recovered raw materials contains a (poly)alkylene glycol.

[0014] 5. The method according to any one of 1. to 4., wherein a solid acid catalyst is used as the catalyst.

[0015] 6. The method according to 5., wherein a crystalline metallosilicate is used as the solid acid catalyst.

[0016] 7. The method according to any one of 1. to 6., further comprising controlling the mass of branched olefins relative to the total mass of branched olefins and linear olefins contained in the recovered raw material so as not to be equal to or less than 1.5 mass%.

[0017] The present invention also includes the following. (1) A method for producing a (poly)alkylene glycol monoalkyl ether by reacting an olefin with a (poly)alkylene glycol in the presence of a catalyst, characterized in that the reaction is carried out by synthesizing a (poly)alkylene glycol monoalkyl ether, and when at least a portion of the raw material is recovered after the synthesis and reused as the raw material, the mass of the branched olefin in the reaction raw material is set to 1% by mass or more and 20% by mass or less relative to the sum of the masses of the branched olefin and linear olefin contained in the reaction raw material. (2) The method according to (1), wherein the olefin has 6 to 20 carbon atoms. (3) The method according to (1) or (2), wherein at least one of the recovered raw materials is an olefin. (4) The method according to (3), wherein the recovered raw material is an olefin from which branched olefins have been separated by distillation. (5) The method according to any one of (1) to (4), wherein at least one of the recovered raw materials is a (poly)alkylene glycol. (6) The method according to any one of (1) to (5), wherein a solid acid catalyst is used as the catalyst. (7) The method according to (6), wherein a crystalline metallosilicate is used as the solid acid catalyst. [Brief explanation of the drawings]

[0018] [Figure 1] 1 shows an example of a reaction apparatus having a batch reactor. [Figure 2] 1 shows an example of a flow diagram of a reactor having a continuous tank reactor. [Figure 3] 1 shows an example of a flow diagram of a reactor having a continuous tank reactor. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described. Note that the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the claims. Furthermore, the embodiments described in this specification can be arbitrarily combined to form other embodiments.

[0020] Throughout this specification, unless otherwise specified, singular expressions should be understood to include the plural concept. Therefore, singular articles (e.g., "a," "an," "the," etc. in English) should be understood to include the plural concept, unless otherwise specified. Furthermore, terms used in this specification should be understood to have the meaning commonly used in the art, unless otherwise specified. Therefore, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification (including definitions) will control.

[0021] In this specification, the range "X to Y" includes X and Y and means "X or more and Y or less." Unless otherwise specified, operations and measurements of physical properties are performed at room temperature (20°C or more and 25°C or less) and at a relative humidity of 40% RH or more and 50% RH or less.

[0022] One aspect of the present invention is a method for producing a (poly)alkylene glycol monoalkyl ether by reacting an olefin and a (poly)alkylene glycol in the presence of a catalyst in a reactor, recovering at least a portion of the raw materials used in the production and reusing them as raw materials, wherein at least one of the recovered raw materials contains an olefin, and controlling the mass of the branched olefin relative to the sum of the masses of the branched olefin and linear olefin contained in the recovered raw materials so as not to exceed 20 mass%. With this configuration, the olefin and the (poly)alkylene glycol can be reacted in the presence of a catalyst to produce a (poly)alkylene glycol monoalkyl ether in high yield over a long period of time.

[0023] According to one embodiment of the present invention, a (poly)alkylene glycol monoalkyl ether is continuously produced by reacting an olefin with a (poly)alkylene glycol in the presence of a catalyst in a reactor. According to one embodiment of the present invention, the continuous operation time is 20 to 20,000 hours, 100 to 15,000 hours, or 200 to 10,000 hours. The continuous operation time is preferably the time from when recovered olefins, which have been treated to remove at least a portion of the branched olefins, are discharged from the treatment equipment (e.g., a distillation column) toward the reactor (in FIG. 2, when the recovered unreacted olefins are introduced into conduit 26) to when the supply of raw materials to the reactor is stopped (in FIG. 2, when no raw materials are supplied to reactor 11).

[0024] The olefin used in the present invention is preferably a hydrocarbon having 6 to 30 carbon atoms and an ethylenically unsaturated bond, more preferably a hydrocarbon having 6 to 20 carbon atoms and an ethylenically unsaturated bond, and even more preferably a hydrocarbon having 8 to 20 carbon atoms and an ethylenically unsaturated bond. The olefin used in the present invention is more preferably a hydrocarbon having 9 to 18 carbon atoms and an ethylenically unsaturated bond, or a hydrocarbon having 12 to 16 carbon atoms and an ethylenically unsaturated bond. Considering that the target (poly)alkylene glycol monoalkyl ether will be used as a surfactant, such an olefin is preferably composed primarily of an acyclic olefin, and more preferably of a linear olefin. "Composed primarily of an acyclic (linear) olefin" means that the olefin contains 80% by mass or more, 85% by mass or more, or 90% by mass or more of acyclic (linear) olefins. While industrially readily available linear olefins usually contain branched olefins, it is preferable to use such linear olefins as raw materials due to their low cost. These linear olefins that are easily available industrially contain branched olefins in an amount ranging from a few ppm to a few percent at most, although the concentration varies depending on the raw material manufacturer. The raw olefin (fresh olefin) used in the production of the present invention is a linear olefin containing preferably 0.01 to 10 mass%, more preferably 0.1 to 10 mass%, and even more preferably 1 to 8 mass% of branched olefins. The raw olefin (fresh olefin) used in the present invention is a linear olefin containing 1.2 to 7 mass%, 1.4 to 6 mass%, or 1.6 to 5.5 mass% of branched olefins.

[0025] Thus, acyclic (linear) olefins (fresh olefins) that can be used as raw materials for producing (poly)alkylene glycol monoalkyl ethers can be in the form of a mixture containing branched olefins. However, since such olefins are not produced so as to intentionally contain branched olefins, they are also simply referred to as linear olefins (fresh olefins, or simply olefins) even if they contain branched olefins. According to one embodiment of the present invention, the olefins do not contain cyclic olefins, or if they do contain cyclic olefins, the amount of cyclic olefins in the olefins is 1% by mass or less, 0.5% by mass or less, or 0.1% by mass or less.

[0026] Examples of linear olefins include octene, nonene, decene, undecene, dodecene, tridecene, tetradecene, pentadecene, hexadecene, heptadecene, octadecene, nonadecene, eicosene, docosene, tricosene, and tetracosene. The number of carbon atoms in the linear olefin may be 6 to 30, 6 to 20, 8 to 20, 9 to 18, 10 to 17, or 12 to 16. These olefins can be used without particular limitation, regardless of whether the position of the unsaturated bond is the α-position, the inner position, or a mixture of the α-position and the inner position.

[0027] In one embodiment of the present invention, the olefin has an unsaturated bond at the α-position (e.g., 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene). In one embodiment of the present invention, the olefin has an unsaturated bond at the inner position (e.g., inner dodecene, inner tridecene, inner tetradecene, inner pentadecene, inner hexadecene). Furthermore, two or more olefins having different carbon numbers may be mixed and used as the raw material. In one embodiment of the present invention, the olefin is a mixture of an olefin having an unsaturated bond at the α-position and an olefin having an unsaturated bond at the inner position (e.g., a mixture of 1-dodecene and inner dodecene, a mixture of 1-tridecene and inner tridecene, a mixture of 1-tetradecene and inner tetradecene, a mixture of 1-pentadecene and inner pentadecene, a mixture of 1-hexadecene and inner hexadecene). In the reaction process of the present invention, a reaction of isomerizing the position of the unsaturated bond of the olefin simultaneously occurs. In general, for linear olefins, inner olefins are thermodynamically more stable than α-olefins. Therefore, when α-olefins are used as raw materials, the olefins gradually isomerize to inner olefins during the reaction. The rate of isomerization varies depending on the reaction temperature, the type and amount of catalyst. In addition, for branched olefins, structures with multiple olefin moieties are generally thermodynamically stable. Therefore, when branched α-olefins are used, the olefins gradually isomerize to inner olefins with more and more substituents during the reaction. For example, 2-methyl-1-alkenes, which are methyl-substituted at the 2-position and are relatively abundant in industrially available linear α-olefins, gradually isomerize to 2-methyl-2-alkenes during the reaction. The rate of isomerization varies depending on the reaction temperature, the type and amount of catalyst.

[0028] In the present invention, examples of the (poly)alkylene glycol used in the production of the (poly)alkylene glycol monoalkyl ether include monoethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, monopropylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,3-propanediol, 1,2-butanediol, 2,3-butanediol, 1,4-butanediol, 1,6-hexanediol, and 1,4-cyclohexanemethanediol. These may be used alone or in a mixture of two or more. Among these, monoethylene glycol, diethylene glycol, and triethylene glycol are preferred, and monoethylene glycol is more preferred. According to one embodiment of the present invention, the number of carbon atoms in the alkylene group in the (poly)alkylene glycol is 1 to 8, 1 to 6, 1 to 4, or 1 to 3, and most preferably 2.

[0029] Acidic catalysts are suitable for use in the present invention. Examples include homogeneous catalysts such as sulfuric acid, benzenesulfonic acid, dodecylbenzenesulfonic acid, and heteropolyacids (phosphotungstic acid, phosphomolybdic acid, silicotungstic acid, and silicomolybdic acid), as well as solid acid catalysts such as acidic ion exchange resins, composite metal oxides such as silica alumina and titania silica, and zeolites. These catalysts may be used alone or in combination of two or more. Among these, solid acid catalysts are preferred. Compared to homogeneous catalysts, solid acid catalysts can be used repeatedly and continuously, making them particularly effective when used in long-term reactions such as those of the present invention.

[0030] Among these, crystalline metallosilicates are particularly preferred. Crystalline metallosilicates are ordered porous substances with a fixed crystal structure. That is, they are solid substances with a large specific surface area and numerous ordered voids or holes within their structure. The crystalline metallosilicates used in the present invention include crystalline aluminosilicates (commonly known as zeolites) and compounds in which other metal elements are introduced into the crystal lattice in place of the Al atoms of crystalline aluminosilicates. Specific examples of other metal elements include B, Ga, In, Ge, Sn, P, As, Sb, Sc, Y, La, Ti, Zr, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn, which may be used alone or in combination. In view of catalytic activity and ease of synthesis and availability, crystalline aluminosilicate, crystalline ferrosilicate, crystalline borosilicate, and crystalline gallosilicate are preferred, with crystalline aluminosilicate being particularly preferred.

[0031] According to one embodiment of the present invention, the specific surface area of ​​the catalyst is 150 to 1500 m 2 / g or 300-1000m 2 / g.

[0032] Specific examples of crystalline metallosilicates used in the present invention include those having structures such as MFI (ZSM-5, etc.), MEL (ZSM-11, etc.), BEA (β-type zeolite, etc.), FAU (Y-type zeolite, etc.), MOR (mordenite, etc.), MTW (ZSM-12, etc.), and LTL (L-type zeolite, etc.) using the IUPAC code named by the International Zeolite Society Structure Committee. Other examples include those having structures described in "ZEOLITES, Vol. 12, No. 5, 1992" and "HANDBOOK OF MOLECULAR SIEVES," by R. Szostak, published by VAN NOSTRAND REINHOLD. These may be used alone or in combination of two or more. Among these, those having the BEA structure are particularly preferred due to their excellent catalytic activity.

[0033] The crystalline metallosilicates used in the present invention preferably have an atomic ratio of silicon atoms to metal atoms constituting the metal silicates of 5 to 1500, particularly 10 to 500. If the atomic ratio of silicon atoms to metal atoms is too small or too large, the catalytic activity is low, which is undesirable. These crystalline metallosilicates have ion-exchangeable cations outside the crystal lattice, and specific examples of these cations include H + , Li + , Na + , Rb + , Cs + , Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ ,Sc. 3+ , Y 3+ , La 3+ , R4N + , R4P + (R is H or alkyl group). Among them, all or part of the cation is converted to hydrogen ions (H + ) are preferred as catalysts of the present invention.

[0034] The crystalline metallosilicates used in the present invention can be synthesized by a commonly used synthesis method, such as hydrothermal synthesis. These crystalline metallosilicates can be synthesized, for example, by heating a composition consisting of a silica source, a metal source, and a quaternary ammonium salt such as tetraethylammonium salt or tetrapropylammonium salt at a temperature of about 100 to 175°C until crystals are formed, filtering the solid product, washing with water, drying, and then calcining at 350 to 600°C. Metallosilicates with different crystal systems can be obtained by appropriately adjusting the raw materials and synthesis conditions.

[0035] Examples of silica sources that can be used include water glass, silica sol, silica gel, and alkoxysilane. Examples of metal sources that can be used include various inorganic or organic metal compounds. Suitable examples of metal compounds include metal salts such as metal sulfates [e.g., Al2(SO4)3], metal nitrates [e.g., Fe(NO3)3], and alkali metal salts of metal oxides [e.g., NaAlO2]; metal halides such as metal chlorides [e.g., TiCl4] and metal bromides [e.g., MgBr2]; and metal alkoxides [e.g., Ti(OC2H5)4]. The resulting crystalline metallosilicate can be ion-exchanged to the desired cation, if necessary. For example, H + The cationic form is prepared by mixing and stirring the crystalline metallosilicate in an aqueous solution of HCl, NH4Cl, NH3, etc., and converting the cationic species into H + type or NH4 + The solid product is then filtered, washed with water, dried, and calcined at 350 to 600°C. + Cationic forms other than those mentioned above can be prepared by carrying out the same procedure using an aqueous solution containing the desired cation.

[0036] These crystalline metallosilicates may be crystalline metallosilicates of a single crystal system, or crystalline metallosilicates of various crystal systems may be used in combination. In the present invention, the catalyst may be used in any form, such as powder, granules, or a molded body having a specific shape. When a molded body is used, alumina, silica, titania, or the like may be used as a carrier or binder. When a homogeneous catalyst is used as the catalyst, it may be dissolved in the reaction raw materials and used.

[0037] The reaction of the olefin with the (poly)alkylene glycol in the present invention can be carried out either in the presence or absence of a solvent, such as nitromethane, nitroethane, nitrobenzene, dioxane, ethylene glycol dimethyl ether, diglyme, sulfolane, benzene, toluene, xylene, hexane, cyclohexane, decane, or paraffin.

[0038] The reaction of the olefin with the (poly)alkylene glycol in the present invention can be carried out by a commonly used method such as a batch reaction or a flow reaction, and is not particularly limited. The molar ratio of the olefin and (poly)alkylene glycol, which are the raw materials for the reaction, is not particularly limited, but the molar ratio of the (poly)alkylene glycol to the olefin is preferably 0.05 to 20, more preferably 0.1 to 10, and even more preferably 1 to 5. The reaction temperature is preferably 50 to 250°C, more preferably 100 to 200°C, and the reaction pressure may be reduced pressure, normal pressure, or increased pressure, but is preferably in the range of normal pressure to 2 MPa.

[0039] According to one embodiment of the present invention, the mass of the catalyst relative to the mass of the (poly)alkylene glycol is preferably 0.1 to 100 mass %, 0.5 to 50 mass %, or 1 to 20 mass %.

[0040] According to one embodiment of the present invention, there is provided a method for producing a (poly)alkylene glycol monoalkyl ether, which comprises reacting an olefin with a (poly)alkylene glycol in the presence of a catalyst in a reactor, and recovering at least a portion of the raw materials used in the production and reusing them as raw materials, wherein at least one of the recovered raw materials contains an olefin, and the molar ratio of the (poly)alkylene glycol to the olefins (branched olefin and linear olefin) supplied to the reactor is controlled to be preferably 0.05 to 20, more preferably 0.1 to 10, and even more preferably 1 to 5.

[0041] According to one embodiment of the present invention, there is provided a method for producing a (poly)alkylene glycol monoalkyl ether, which comprises reacting an olefin with a (poly)alkylene glycol in the presence of a catalyst in a reactor, and recovering at least a portion of the raw materials used in the production and reusing them as raw materials, wherein at least one of the recovered raw materials contains an olefin, and the mass of the catalyst relative to the mass of the (poly)alkylene glycol supplied to the reactor is controlled to be 0.1 to 100 mass%, 0.5 to 50 mass%, or 1 to 20 mass%.

[0042] In the reaction of olefins with (poly)alkylene glycols, branched olefins, (poly)alkylene glycol dialkyl ethers, and alcohols are produced as side reactions. Branched olefins are produced during the reaction by the isomerization of linear olefins in the presence of an acid catalyst. They are also produced by the reverse reaction of the product or (poly)alkylene glycol dialkyl ethers with an acid. While branched olefins are produced by these side reactions, the yield of the side reaction from linear olefins to branched olefins is not high, and is not particularly problematic in short-term reactions. Accumulation of branched olefins in the reaction system is particularly noticeable when a process of recovering and recycling unreacted raw materials is carried out over a long period of time.

[0043] Since the (poly)alkylene glycol dialkyl ether and / or alcohol can selectively produce the (poly)alkylene glycol alkyl ether, they may be supplied to the reaction system of the olefin and (poly)alkylene glycol, with no particular limitation on the amount supplied. The by-product (poly)alkylene glycol dialkyl ether or alcohol may be recovered and stored and supplied to the reaction system all at once, or the by-product (poly)alkylene glycol dialkyl ether or alcohol from the previous reaction may be continuously supplied to the next reaction. When a flow reaction is performed to continuously produce a (poly)alkylene glycol monoalkyl ether, it is preferable to continuously recover the by-product (poly)alkylene glycol dialkyl ether or alcohol and constantly recycle and supply it to the reaction system. The amount of by-product (poly)alkylene glycol dialkyl ether or alcohol produced by the reaction of an olefin and a (poly)alkylene glycol varies depending on the type and molar ratio of the olefin and the (poly)alkylene glycol, the type of catalyst used, the reaction temperature, the reaction time, etc., but is typically in the range of 0.0001 to 30 mol% relative to the olefin used as the raw material. Furthermore, depending on the type of catalyst used, the type of raw material, the reaction conditions, etc., there are cases where either the (poly)alkylene glycol dialkyl ether or the alcohol is not substantially produced as a by-product. Furthermore, there are also cases where either the (poly)alkylene glycol dialkyl ether or the alcohol produced as a by-product is recovered as a product. In such cases, it is sufficient to supply only either the (poly)alkylene glycol dialkyl ether or the alcohol to the reaction system of the olefin and the (poly)alkylene glycol.

[0044] When a batch reactor is used, the reactor is filled with a catalyst, the raw materials olefin and (poly)alkylene glycol, and optionally a (poly)alkylene glycol dialkyl ether and / or alcohol, and the mixture is stirred at a predetermined temperature and pressure to obtain a mixture containing the target (poly)alkylene glycol monoalkyl ether. The amount of catalyst used is not particularly limited, but is preferably 0.1 to 100% by mass, more preferably 0.5 to 50% by mass, and even more preferably 1 to 20% by mass, relative to the raw material olefin. The reaction time varies depending on the reaction temperature, catalyst amount, raw material composition, etc., but is generally in the range of 0.1 to 100 hours, preferably 0.5 to 30 hours.

[0045] When a flow reactor is used, any of the following types can be used: fluidized bed, moving bed, fixed bed, and stirred tank. The reaction conditions vary depending on the raw material composition, catalyst concentration, reaction temperature, etc., but the liquid hourly space velocity (LHSV), i.e., the volumetric flow rate of the flowing raw material divided by the volume of the reactor, should be 0.01 to 50 h -1 , especially 0.1~20hr -1 Since the present invention is based on a long-term reaction, it is preferable to use a flow reactor.

[0046] When using a fluidized bed, moving bed, or stirred tank reactor, it is preferable not to add a solvent. The raw materials, (poly)alkylene glycol and olefin, have only slight solubility in each other, and only dissolve to that extent. Therefore, the reaction solution usually separates into two phases. The catalyst (a solid catalyst such as a crystalline metallosilicate) is dispersed in the (poly)alkylene glycol phase, while the product (poly)alkylene glycol monoalkyl ether and the branched olefins, (poly)alkylene glycol dialkyl ethers, and alcohols produced by side reactions are primarily contained in the olefin phase. Therefore, after the reaction is complete, the (poly)alkylene glycol phase and the olefin phase are separated, and the desired (poly)alkylene glycol monoalkyl ether can be obtained from the olefin phase by methods such as distillation or extraction.

[0047] On the other hand, when a fixed-bed reactor is used, it is preferable to add a solvent during the reaction to make the raw materials (poly)alkylene glycol and olefin mutually compatible under the reaction conditions. In this case, the cost required for separation after the reaction can be reduced, so the (poly)alkylene glycol phase and the product (poly)alkylene glycol monoalkyl ether and the olefin are separated by side reactions. Generate It is preferable to be able to separate the resulting (poly)alkylene glycol monoalkyl ether from the olefin phase containing the branched olefin, (poly)alkylene glycol dialkyl ether, and alcohol. Specifically, by appropriately controlling the amount of solvent added, the type of solvent, and the temperature, or by removing the solvent by a method such as distillation after the reaction, the phase separation can be achieved, and the (poly)alkylene glycol phase and the olefin phase can be separated after the reaction is completed, and the target (poly)alkylene glycol monoalkyl ether can be obtained from the olefin phase by a method such as distillation or extraction.

[0048] Furthermore, olefins that have been used as raw materials but have not reacted can be recovered and reused as raw materials for the reaction with (poly)alkylene glycol, and it is preferable to add olefins that are insufficient for the reaction. In this case, at least a portion of the branched olefins contained in the unreacted olefins can be removed by distillation, and the remaining olefins after removing at least a portion of the branched olefins can be supplied to the reaction system of the olefin and (poly)alkylene glycol as described above and reused as raw materials.

[0049] Among the unreacted olefins, the target (poly)alkylene glycol monoalkyl ether product, and the by-product branched olefins, alcohols, and (poly)alkylene glycol dialkyl ethers contained in the olefin phase, the branched olefins generally have the lowest boiling point, followed by the linear olefins, alcohols, (poly)alkylene glycol monoalkyl ethers, and (poly)alkylene glycol dialkyl ethers. Therefore, by distillation, the branched olefins are first removed as a fraction, followed by the unreacted olefins and alcohols as fractions. The (poly)alkylene glycol monoalkyl ethers are then recovered as a product, and the (poly)alkylene glycol dialkyl ethers are recovered as distillation bottoms. The (poly)alkylene glycol monoalkyl ethers recovered as a product can also be further purified by distillation or washing. The unreacted olefins from which at least a portion of the branched olefins have been removed and the by-product alcohols and / or (poly)alkylene glycol dialkyl ethers can be recycled and used in the reaction system between the olefin and the (poly)alkylene glycol. In addition, for the purpose of purging impurities such as heavy components, a part of the distillation bottoms can be discarded and the remainder can be recycled by supplying it to the reaction system of olefin and (poly)alkylene glycol.

[0050] Since linear olefins and branched olefins have similar boiling points, when branched olefins are distilled off from unreacted olefins, linear olefins are also distilled off. Therefore, if all of the branched olefins are distilled off, the recovery rate of unreacted olefins decreases, and in long-term reactions, the olefin utilization efficiency decreases (i.e., the amount of olefin removed is greater than the amount of olefin charged). Here, the olefin utilization efficiency can be calculated using the following formula:

[0051] Olefin utilization efficiency (mol%) = { (Total number of moles of (poly)alkylene glycol monoalkyl ether finally produced) / (Total number of moles of fresh olefins charged as raw material)}×100 .

[0052] For these reasons, when recycling and reusing unreacted olefins, it is preferable not to distill off all of the branched olefins from the unreacted olefins. Specifically, it is preferable to control the concentration of branched olefins in the olefins recovered and reused as raw materials (branched olefins and linear olefins flowing through conduit 26 in FIG. 2, and branched olefins and linear olefins flowing through conduit 58 in FIG. 3) to be at a certain value or higher. Specifically, the mass of branched olefins relative to the sum of the masses of the olefins recovered and reused as raw materials (including branched olefins and linear olefins) is controlled so as not to be less than 1% by mass. In this specification, the mass of branched olefins relative to the sum of the masses of branched olefins and linear olefins is also referred to as the branched olefin ratio.

[0053] Furthermore, as described above, a high branched olefin ratio leads to a decrease in the yield of (poly)alkylene glycol monoalkyl ether and a decrease in catalytic activity. Therefore, the branched olefin ratio in the olefins recovered and reused as raw materials (the branched olefins and linear olefins flowing through conduit 26 in FIG. 2, and the branched olefins and linear olefins flowing through conduit 58 in FIG. 3) is controlled so as not to exceed 20 mass%.

[0054] By controlling the ratio within such a range, a decrease in the yield of (poly)alkylene glycol monoalkyl ether due to branched olefins can be suppressed, and the utilization efficiency of olefins can be maintained at a high level (i.e., the amount of olefins removed relative to the amount of olefins charged can be reduced). According to one embodiment of the present invention, the mass of branched olefins relative to the sum of the masses of branched olefins and linear olefins present in the reaction raw material (olefin) recovered and reused as a raw material (branched olefin ratio) is controlled to not more than 1.5 mass%, 1.7 mass%, 2 mass%, 2.2 mass%, 2.4 mass%, 2.6 mass%, or 2.8 mass%. According to one embodiment of the present invention, the mass of branched olefins relative to the sum of the masses of branched olefins and linear olefins present in the reaction raw material (olefin) recovered and reused as a raw material (branched olefin ratio) is controlled to not more than 20 mass%, 15 mass% or more, 10 mass% or more, 9 mass% or more, 8 mass% or more, 7 mass% or more, or 6 mass% or more. The branched olefin ratio is measured as follows. That is, it is calculated from the area of ​​the linear olefin and the area of ​​the branched olefin measured using gas chromatography (GC) according to the following formula.

[0055] Branched olefin ratio (mass%) = { ( Branch Area obtained from GC analysis of olefins) / {(area obtained from GC analysis of linear olefins)+(area obtained from GC analysis of branched olefins)} }×100 .

[0056] The analytical conditions for gas chromatography (GC) are as follows: ≪GC conditions≫ Gas chromatography equipment: Shimadzu Corporation, product name: Nexis TM GC-2030 Column: Agilent Technologies, product name: DB-1 (column length: 60 m, inner diameter: 0.25 mm, film thickness: 0.25 μm) Detector: FID detection method Injection volume: 1μl Linear speed: 14cm / sec Carrier gas: N2 Temperature increase conditions: the temperature was increased from 60°C to 100°C at 3°C / min, then increased to 320°C at 10°C / min, and maintained at 320°C for 30 minutes.

[0057] In the present invention, the mass of branched olefins relative to the total mass of branched olefins and linear olefins contained in the raw material supplied to the reactor (branched olefin ratio) is also preferably controlled so as not to exceed 20% by mass, more preferably 15% by mass or more, 10% by mass or more, 9% by mass or more, 8% by mass or more, 7% by mass or more, or 6% by mass or more. The mass of branched olefins relative to the total mass of branched olefins and linear olefins contained in the raw material supplied to the reactor is also preferably controlled so as not to be less than 1% by mass, more preferably 1.5% by mass or less, 1.7% by mass or less, 1.9% by mass or less, 2% by mass or less, 2.2% by mass or less, 2.4% by mass or less, 2.6% by mass or less, or 2.8% by mass or less.

[0058] When using a fluidized bed, moving bed, or stirred tank reactor, the catalyst can be separated from the catalyst-containing (poly)alkylene glycol phase by methods such as centrifugation, filtration, or drying, and recycled for use in the next reaction. Alternatively, the (poly)alkylene glycol can be recovered from the (poly)alkylene glycol phase by methods such as distillation and recycled for use in the next reaction with an olefin. The catalyst-containing (poly)alkylene glycol phase is recycled for the next reaction and used in the reaction with an olefin. However, it is preferable to perform this step after (or while) replenishing the (poly)alkylene glycol consumed in the reaction, as this simplifies the process. Since the activity of the catalyst may gradually decrease during the reaction, if a decrease in catalyst activity is detected, at least a portion of the catalyst can be extracted and regenerated, or a new catalyst can be replenished and supplied to the next reaction. Furthermore, if impurities such as heavy components accumulate in the (poly)alkylene glycol phase, a portion of the (poly)alkylene glycol phase can be extracted to purge these impurities, and the remainder can be recycled to the next reaction. On the other hand, when a fixed-bed reactor is used and the activity of the catalyst decreases due to the reaction, the activity may be improved by regenerating the catalyst in the fixed bed or by replacing the catalyst. When a fixed-bed reactor is used, it is not necessary to stop the reaction when regenerating the catalyst, so it is preferable to prepare at least two or more reactors and alternately carry out the reaction and catalyst regeneration.

[0059] The distillation temperature varies depending on the material to be separated by distillation, but for example, the temperature at the top of the distillation column is usually 15 to 300°C, or 50 to 300°C, preferably 60 to 300°C, and more preferably 70 to 280°C.

[0060] The distillation residence time is usually 24 hours or less, preferably 12 hours or less, and more preferably 6 hours or less. The distillation residence time is preferably 5 minutes or more, more preferably 10 minutes or more, and even more preferably 15 minutes or more. Distillation may be performed under either atmospheric pressure or reduced pressure, but is preferably performed under reduced pressure, with a preferred reduced pressure of 15 kPa or less, more preferably 10 kPa or less. A preferred reduced pressure is 50 Pa or more, more preferably 100 Pa or more. The number of theoretical plates in the distillation column depends on the substance to be separated by distillation, but is preferably 2 or more, more preferably 3 or more, and even more preferably 5 or more. If the number of plates is too small, separation by distillation may not be possible. Furthermore, the number of theoretical plates is preferably 150 or less, more preferably 100 or less, and even more preferably 50 or less. A large number of theoretical plates requires a large distillation column, which increases fixed costs and is therefore undesirable from an industrial standpoint.

[0061] Next, an embodiment of the present invention will be described with reference to the drawings. First, an example of a method for producing a (poly)alkylene glycol monoalkyl ether using a reaction apparatus having a batch reactor as a reactor will be described with reference to FIG. 1. As shown in FIG. 1, the reaction apparatus comprises a batch reactor 1 and a distillation column 2. The batch reactor 1 is pressure-resistant and equipped with a stirrer 1a and a heater 1b. A raw material supply pipe 4 and an extraction pipe 5 are connected to the batch reactor 1. The top of the batch reactor 1 and the bottom of the distillation column 2 are connected by a conduit 3, so that gas generated from the batch reactor 1 can be introduced into the distillation column 2 and the bottom liquid of the distillation column 2 can be returned to the batch reactor 1. An extraction pipe 6 for extracting a distillate is connected to the top of the distillation column 2.

[0062] First, the first reaction is carried out in the absence of (poly)alkylene glycol dialkyl ether and / or alcohol. The reaction raw materials, namely, olefin, (poly)alkylene glycol, catalyst, and, if necessary, solvent, are charged into batch reactor 1 via raw material supply pipe 4. The reaction mixture is then heated with stirring to react at a predetermined temperature and pressure to synthesize (poly)alkylene glycol monoalkyl ether. During this reaction, branched olefin, (poly)alkylene glycol dialkyl ether, and / or alcohol are produced as by-products. After the reaction is complete, the stirrer is stopped and the mixture is allowed to stand, allowing the mixture to separate into a catalyst / (poly)alkylene glycol phase (lower layer) and an olefin phase (upper layer) containing (poly)alkylene glycol monoalkyl ether and the by-product branched olefin. Depending on the shape and size of the catalyst, the catalyst may be dispersed in the (poly)alkylene glycol phase.

[0063] If the reaction solution does not separate after the reaction because a solvent was used during the reaction, the phase separation temperature may be changed to a temperature at which the reaction solution separates into two phases, or the solvent may be first removed by distillation or the like to cause phase separation, but it is preferable to separate the catalyst first. If the catalyst can be recovered by filtration or the like, it is recovered. If the catalyst cannot be separated due to its shape, size, or the like, it is preferable to separate the (poly)alkylene glycol phase (lower layer) containing the catalyst from the olefin phase (upper layer) containing the (poly)alkylene glycol monoalkyl ether and the by-product branched olefin.

[0064] The separated catalyst and the (poly)alkylene glycol phase containing the catalyst are then withdrawn from the batch reactor 1 via withdrawal pipe 5. The olefin phase remaining in the batch reactor 1 is separated into its components by batch distillation. While controlling the pressure in the batch reactor 1 and distillation column 2, the temperature of the olefin phase remaining in the batch reactor 1, and the reflux ratio of the distillation column 2, the components present in the olefin phase are withdrawn as a distillate from the top of the distillation column via withdrawal pipe 6, in order of lowest boiling point. First, at least a portion of the branched olefins, which are by-products, are removed. Next, the unreacted olefins and by-product alcohol, which remain after at least a portion of the branched olefins have been removed, are recovered. Finally, the target product, (poly)alkylene glycol monoalkyl ether, is recovered. Alternatively, the branched olefins, unreacted olefins, and by-product alcohol may be recovered simultaneously first, and this liquid may be used in a separate distillation column to remove the branched olefins, which are by-products. The by-product (poly)alkylene glycol dialkyl ether may be subsequently recovered by distillation, or may be left as distillation bottoms in the batch reactor 1 and supplied to the next batch reaction. The distillation of the olefin phase may also be carried out using a distillation apparatus (not shown) other than the distillation column 2.

[0065] Next, the second and subsequent reactions will be described. From the second reaction onward, the by-product (poly)alkylene glycol dialkyl ether and / or alcohol are supplied to the reaction system to carry out the reaction. The unreacted olefins from which at least a portion of the branched olefins have been removed and the (poly)alkylene glycol phase are also reused for the reaction. The unreacted olefins from which at least a portion of the branched olefins have been removed, the catalyst-containing (poly)alkylene glycol phase, and the by-product (poly)alkylene glycol dialkyl ether and / or alcohol recovered from the previous batch reaction are used as reaction raw materials. Furthermore, the olefins and (poly)alkylene glycol consumed in the previous reaction are replenished and charged into the batch reactor 1 via the raw material supply pipe 4. If the (poly)alkylene glycol dialkyl ether is left as the distillation bottoms in the batch reactor 1, there is no need to supply the (poly)alkylene glycol dialkyl ether via the raw material supply pipe 4. After the raw materials are supplied, the reaction is carried out under the same conditions as in the previous reaction, and the components are separated and recovered under the same conditions as in the previous reaction. By repeating the batchwise reaction while removing the branched olefin, which is the lightest-boiling component, during such distillation, the branched olefin by-product does not accumulate in the system, and the by-product (poly)alkylene glycol dialkyl ether and / or alcohol is converted to a (poly)alkylene glycol monoalkyl ether, allowing a (poly)alkylene glycol monoalkyl ether to be obtained highly selectively and efficiently from the olefin and (poly)alkylene glycol. Furthermore, if impurities such as heavy components accumulate in the (poly)alkylene glycol phase or the olefin phase as a result of repeating the batchwise reaction, the heavy components can be removed by purging a portion of the (poly)alkylene glycol phase or by purging a portion of the bottoms obtained by distilling the olefin phase.

[0066] Next, an example of a method for producing a (poly)alkylene glycol monoalkyl ether using a reaction apparatus having a flow reactor as a reactor will be described with reference to FIGS.

[0067] The reaction can be carried out using any of the fluidized bed, moving bed, fixed bed, and stirred tank types. Here, we will use a continuous tank reactor as an example, as shown in Figures 2 and 3.

[0068] In Figure 2, the reaction system having a flow reactor is composed of continuous tank reactors 11 and 12, and distillation columns 14, 15, and 16. Continuous tank reactors 11 and 12 are equipped with agitators 11a and 12a, and heaters 11b and 12b, respectively. A raw material supply pipe 20 is connected to continuous tank reactor 11, and an overflow conduit 21 is connected to the top of continuous tank reactor 11. Conduit 21 also serves as the raw material supply pipe for continuous tank reactor 12. An overflow conduit 22 is connected to the top of continuous tank reactor 12, and the raw material is introduced into liquid-liquid separator (settler) 13. Liquid-liquid separator 13 and distillation column 14 are connected by conduit 23, and the upper liquid separated by liquid-liquid separator 13 is introduced into distillation column 14. Furthermore, liquid-liquid separator 13 and raw material supply pipe 20 are connected by conduit 24, so that the lower layer liquid separated by liquid-liquid separator 13 can be returned to continuous tank reactor 11. Conduit 25 is connected to the middle of conduit 24. The bottom of distillation column 14 and distillation column 15 are connected by conduit 27, so that the bottom liquid of distillation column 14 is introduced into distillation column 15. The top of distillation column 14 is connected to conduit 31. The bottom of distillation column 15 and distillation column 16 are connected by conduit 28, so that the bottom liquid of distillation column 15 is introduced into distillation column 16. The top of distillation column 15 and raw material supply pipe 20 are connected by conduit 26, so that the distillate from the top of distillation column 15 can be returned to continuous tank reactor 11. The bottom of distillation column 16 and raw material supply pipe 20 are connected by conduit 29, so that the bottom liquid of distillation column 16 can be returned to continuous tank reactor 11. Conduit 30 is connected to the middle of conduit 29. Conduit 32 is connected to the top of distillation column 16.

[0069] First, the reaction raw materials, i.e., linear olefin, (poly)alkylene glycol, catalyst, and, if necessary, solvent, are continuously charged into continuous-tank reactor 11 via raw material supply pipe 20. Next, this reaction liquid is heated with stirring to react under predetermined temperature and pressure conditions to synthesize a (poly)alkylene glycol monoalkyl ether. During this reaction, branched olefins and (poly)alkylene glycol dialkyl ethers and / or alcohols are produced as by-products. The overflow of the reaction liquid is introduced into continuous-tank reactor 12, where the reaction continues, and the overflow is introduced into liquid-liquid separator 13. In liquid-liquid separator 13, the reaction liquid is separated into a (poly)alkylene glycol phase (lower layer) containing the catalyst and an olefin phase (upper layer) containing the (poly)alkylene glycol monoalkyl ether, branched olefin, (poly)alkylene glycol dialkyl ether, and alcohol. The (poly)alkylene glycol phase is then withdrawn via conduit 24 and charged into continuous-tank reactor 11 via raw material supply pipe 20, with the (poly)alkylene glycol consumed in the reaction being replenished as necessary. A portion of the (poly)alkylene glycol phase is withdrawn from conduit 25, connected midway through conduit 24, to partially regenerate the catalyst. The catalyst and (poly)alkylene glycol are recovered from the (poly)alkylene glycol phase withdrawn via conduit 25, and the catalyst is regenerated. The regenerated catalyst and recovered (poly)alkylene glycol are then fed back into continuous-tank reactor 11 via raw material supply pipe 20. If impurities such as heavy materials resulting from side reactions such as dehydration condensation or water accumulate in the (poly)alkylene glycol phase, they can be removed from the system by withdrawing a portion of the (poly)alkylene glycol phase for catalyst regeneration. The upper olefin phase in liquid-liquid separation device 13 is introduced into distillation column 14 via conduit 23. While controlling the pressure in the distillation column 14, the temperature of the olefin phase, and the reflux ratio of the distillation column 14, low-boiling point components present in the olefin phase, i.e., branched olefins, are at least partially removed via conduit 31. This makes it possible to reduce the concentration of branched olefins that accumulate in the reaction system.

[0070] According to one embodiment of the present invention, the proportion of (poly)alkylene glycol monoalkyl ethers and (poly)alkylene glycol dialkyl ethers in the liquid introduced into distillation column 14 (the liquid flowing through conduit 23) is typically greater than 1.0 mass%.

[0071] According to one embodiment of the present invention, the distillation column (distillation column 14 in FIG. 2) for removing at least a portion of the branched olefins has a top pressure of preferably 0.01 to 50 kPa, 0.05 to 20 kPa, or 0.1 to 10 kPa. According to one embodiment of the present invention, the distillation column (distillation column 14 in FIG. 2) for removing at least a portion of the branched olefins has a bottom temperature of preferably 50 to 250°C, 70 to 220°C, or 80 to 200°C. According to one embodiment of the present invention, the distillation column (distillation column 14 in FIG. 2) for removing at least a portion of the branched olefins has a top temperature of preferably 30 to 200°C, 50 to 180°C, or 60 to 150°C. According to one embodiment of the present invention, the distillation column (distillation column 14 in FIG. 2) for removing at least a portion of the branched olefins has a reflux ratio of preferably 0.01 to 300, 0.1 to 200, or 1 to 100.

[0072] The (unreacted) olefin from which the branched olefins have at least partially been removed, the (poly)alkylene glycol monoalkyl ether, the (poly)alkylene glycol dialkyl ether, and the alcohol are introduced into distillation column 15 from the bottom of distillation column 14 via conduit 27.

[0073] According to one embodiment of the present invention, the branched olefin ratio in the liquid (flowing through conduit 27) that has been treated to remove at least a portion of the branched olefins (to be introduced into the next distillation column) is controlled to be not less than 1 mass%, not more than 1.5 mass%, not more than 1.7 mass%, not more than 1.9 mass%, not more than 2 mass%, not more than 2.2 mass%, not more than 2.4 mass%, not more than 2.6 mass%, or not more than 2.8 mass%. According to one embodiment of the present invention, the branched olefin ratio in the liquid (flowing through conduit 27) that has been treated to remove at least a portion of the branched olefins (to be introduced into the next distillation column) is controlled to be not more than 20 mass%, not more than 15 mass%, not more than 10 mass%, not more than 9 mass%, not more than 8 mass%, not more than 7 mass%, or not more than 6 mass%.

[0074] While controlling the pressure of distillation column 15, the temperature of the olefin phase, and the reflux ratio of distillation column 15, the components with the next lowest boiling points present in the olefin phase, i.e., unreacted olefins and by-product alcohols, are withdrawn as a distillate from the top of distillation column 15 via conduit 26.

[0075] According to one embodiment of the present invention, the branched olefin ratio in conduit 26 is controlled to be less than 1.0 mass%, preferably not more than 1.5 mass%, not more than 1.7 mass%, not more than 1.9 mass%, not more than 2 mass%, not more than 2.2 mass%, not more than 2.4 mass%, not more than 2.6 mass%, or not more than 2.8 mass%. According to one embodiment of the present invention, the branched olefin ratio in conduit 26 is controlled to be not more than 20 mass%, not more than 15 mass%, not more than 10 mass%, not more than 9 mass%, not more than 8 mass%, not more than 7 mass%, or not more than 6 mass%.

[0076] According to one embodiment of the present invention, the pressure at the top of the distillation column (distillation column 15 in FIG. 2) for recovering unreacted olefins is preferably 0.01 to 50 kPa, 0.05 to 20 kPa, or 0.1 to 10 kPa.

[0077] According to one embodiment of the present invention, the bottom temperature of the distillation column (distillation column 15 in FIG. 2) for recovering unreacted olefins is preferably 100 to 300°C, 120 to 280°C, or 140 to 250°C. According to one embodiment of the present invention, the top temperature of the distillation column (distillation column 15 in FIG. 2) for recovering unreacted olefins is preferably 30 to 200°C, 50 to 180°C, or 70 to 150°C. According to one embodiment of the present invention, the reflux ratio of the distillation column (distillation column 15 in FIG. 2) for recovering unreacted olefins is preferably 0.01 to 300, 0.05 to 100, or 0.1 to 50.

[0078] The olefin and alcohol extracted from the top of the distillation column 15 are extracted via a conduit 26 and fed to the continuous tank reactor 11 via a raw material supply pipe 20, and at this time, the linear olefin consumed in the reaction is replenished as necessary.

[0079] The (poly)alkylene glycol monoalkyl ether and by-product (poly)alkylene glycol dialkyl ether withdrawn from the bottom of distillation column 15 are introduced into distillation column 16 via conduit 28. While controlling the pressure of distillation column 16, the temperature of the (poly)alkylene glycol monoalkyl ether phase, and the reflux ratio of distillation column 16, the (poly)alkylene glycol monoalkyl ether, which is the target reactant and is a component with a low boiling point, is withdrawn as a distillate from the top of distillation column 16 via conduit 32.

[0080] According to one embodiment of the present invention, the top pressure of the distillation column (distillation column 16 in FIG. 2) for obtaining the target (poly)alkylene glycol monoalkyl ether is preferably 10 to 3,000 Pa, 20 to 1,000 Pa, or 30 to 500 Pa. According to one embodiment of the present invention, the bottom temperature of the distillation column (distillation column 16 in FIG. 2) for obtaining the target (poly)alkylene glycol monoalkyl ether is preferably 100 to 350°C, 130 to 320°C, or 150 to 280°C. According to one embodiment of the present invention, the top temperature of the distillation column (distillation column 16 in FIG. 2) for obtaining the target (poly)alkylene glycol monoalkyl ether is preferably 50 to 300°C, 80 to 280°C, or 100 to 250°C. According to one embodiment of the present invention, the reflux ratio of the distillation column (distillation column 16 in FIG. 2) for obtaining the target (poly)alkylene glycol monoalkyl ether is preferably 0.01 to 300, 0.05 to 100, or 0.1 to 50.

[0081] The (poly)alkylene glycol dialkyl ether withdrawn from the bottom of distillation column 16 is fed via conduit 29 and further via raw material supply pipe 20 to continuous tank reactor 11. When impurities such as heavy components accumulate in the (poly)alkylene glycol dialkyl ether phase, the heavy components can be removed by purging a portion of the (poly)alkylene glycol dialkyl ether phase via conduit 30. By repeating this flow reaction, the by-product (poly)alkylene glycol dialkyl ether and / or alcohol are converted into (poly)alkylene glycol monoalkyl ether, and (poly)alkylene glycol monoalkyl ether can be obtained highly selectively and efficiently from olefin and (poly)alkylene glycol.

[0082] In Figure 3, the reaction system having a flow reactor is composed of continuous tank reactors 41 and 42, and distillation columns 44, 45, and 46. Continuous tank reactors 41 and 42 are equipped with agitators 41a and 42a, and heaters 41b and 42b, respectively. A raw material supply pipe 50 is connected to continuous tank reactor 41, and an overflow conduit 51 is connected to the top of continuous tank reactor 41. Conduit 51 also serves as the raw material supply pipe for continuous tank reactor 42. An overflow conduit 52 is connected to the top of continuous tank reactor 42, and the raw material is introduced into liquid-liquid separator (settler) 43. Liquid-liquid separator 43 and distillation column 44 are connected by conduit 53, and the upper liquid separated by liquid-liquid separator 43 is introduced into distillation column 44. Furthermore, the liquid-liquid separator 43 and the raw material supply pipe 50 are connected by a conduit 54, so that the lower layer liquid separated by the liquid-liquid separator 43 can be returned to the continuous tank reactor 41. A conduit 55 is connected to the middle of the conduit 54. The top of the distillation column 44 and the distillation column 45 are connected by a conduit 56, so that the distillate from the distillation column 44 is introduced into the distillation column 45 by the conduit 56. The bottom of the distillation column 44 and the distillation column 46 are connected by a conduit 57, so that the bottom liquid from the distillation column 44 is introduced into the distillation column 46. Furthermore, the top of the distillation column 45 is connected to a conduit 61. The bottom of the distillation column 45 and the raw material supply pipe 50 are connected by a conduit 58, so that the bottom liquid from the distillation column 45 is introduced into the continuous tank reactor 41. 41 The bottom of distillation column 46 and raw material supply pipe 50 are connected by conduit 59, so that the bottom liquid of distillation column 46 can be returned to continuous tank reactor 41. Conduit 60 is connected to the middle of conduit 59. Conduit 62 is connected to the top of distillation column 46.

[0083] First, the reaction raw materials, i.e., linear olefin, (poly)alkylene glycol, catalyst, and, if necessary, solvent, are continuously charged into a continuous-tank reactor 41 via a raw material supply pipe 50. Next, the reaction liquid is heated with stirring to react under predetermined temperature and pressure conditions to synthesize a (poly)alkylene glycol monoalkyl ether. During this reaction, branched olefins and (poly)alkylene glycol dialkyl ethers and / or alcohols are produced as by-products. The overflow of the reaction liquid is introduced into a continuous-tank reactor 42, where the reaction continues, and the overflow is introduced into a liquid-liquid separator 43. In the liquid-liquid separator 43, the reaction liquid is separated into a (poly)alkylene glycol phase (lower layer) containing the catalyst and an olefin phase (upper layer) containing the branched olefin, (poly)alkylene glycol monoalkyl ether, (poly)alkylene glycol dialkyl ether, and alcohol. Thereafter, the (poly)alkylene glycol phase is extracted via conduit 54 and charged into continuous tank reactor 41 via raw material supply pipe 50, and at this time, the (poly)alkylene glycol consumed by the reaction is replenished as necessary.

[0084] Furthermore, a portion of the (poly)alkylene glycol phase is withdrawn from conduit 55 connected midway through conduit 54 in order to partially regenerate the catalyst. The catalyst and (poly)alkylene glycol are recovered from the (poly)alkylene glycol phase withdrawn from conduit 55, and the catalyst is regenerated. The regenerated catalyst and recovered (poly)alkylene glycol are again supplied to continuous tank reactor 41 via raw material supply pipe 50. Note that, if impurities such as heavy materials generated by side reactions such as dehydration condensation or water accumulate in the (poly)alkylene glycol phase, they can be removed from the system by withdrawing a portion of the (poly)alkylene glycol phase for catalyst regeneration. The upper layer olefin phase in liquid-liquid separation device 43 is introduced into distillation column 44 via conduit 53. While controlling the pressure of distillation column 44, the temperature of the olefin phase, and the reflux ratio of distillation column 44, the low-boiling components present in the olefin phase, i.e., unreacted olefins including branched olefins, and alcohols, are introduced into distillation column 45 from the top of the column via conduit 56.

[0085] According to one embodiment of the present invention, the pressure at the top of the distillation column (distillation column 44 in FIG. 3) into which the liquid-liquid separated olefin phase is introduced is preferably 0.01 to 50 kPa, 0.05 to 20 kPa, or 0.1 to 10 kPa. According to one embodiment of the present invention, the temperature at the bottom of the distillation column (distillation column 44 in FIG. 3) into which the liquid-liquid separated olefin phase is introduced is preferably 30 to 250°C, 50 to 230°C, or 70 to 200°C. According to one embodiment of the present invention, the temperature at the top of the distillation column (distillation column 44 in FIG. 3) into which the liquid-liquid separated olefin phase is introduced is preferably 30 to 230°C, 40 to 210°C, or 50 to 200°C. According to one embodiment of the present invention, the reflux ratio of the distillation column (distillation column 44 in FIG. 3) into which the liquid-liquid separated olefin phase is introduced is preferably 0.01 to 300, 0.05 to 100, or 0.1 to 50. Under these conditions, the (poly)alkylene glycol monoalkyl ether and (poly)alkylene glycol dialkyl ether can be efficiently separated from other components in the liquid-liquid separator.

[0086] Furthermore, while controlling the pressure of distillation column 45, the temperature of the olefin phase, and the reflux ratio of distillation column 45, at least a portion of the branched olefins, which are the components with the lowest boiling points among the components introduced into distillation column 45, are removed via conduit 61. This makes it possible to reduce the concentration of branched olefins that accumulate in the reaction system.

[0087] According to one embodiment of the present invention, the top pressure of the distillation column (distillation column 45 in FIG. 3) for removing at least a portion of the branched olefins is preferably 0.01 to 50 kPa, 0.05 to 20 kPa, or 0.1 to 10 kPa. According to one embodiment of the present invention, the bottom temperature of the distillation column (distillation column 45 in FIG. 3) for removing at least a portion of the branched olefins is preferably 30 to 230°C, 40 to 210°C, or 50 to 200°C. According to one embodiment of the present invention, the top temperature of the distillation column (distillation column 45 in FIG. 3) for removing at least a portion of the branched olefins is preferably 30 to 200°C, 40 to 180°C, or 50 to 150°C. According to one embodiment of the present invention, the top temperature of the distillation column (distillation column 45 in FIG. 3) for removing at least a portion of the branched olefins is preferably less than 80°C if the top pressure is set to 0.9 to 1.0 kPa.

[0088] In this embodiment, the proportion of (poly)alkylene glycol monoalkyl ethers and (poly)alkylene glycol dialkyl ethers in the liquid introduced into the distillation column (the liquid flowing through conduit 56) is typically 1.0 mass% or less, or 0.5 mass% or less. According to one embodiment of the present invention, the reflux ratio of the distillation column for removing at least a portion of the branched olefins (distillation column 45 in FIG. 3) is preferably 0.01 to 300, 0.05 to 200, or 0.1 to 100.

[0089] The unreacted olefins and alcohol from which at least a portion of the branched olefins have been removed are fed from the bottom of distillation column 45 via conduit 58 and further via raw material supply pipe 50 into continuous tank reactor 41, and at this time, linear olefins consumed by the reaction are replenished as necessary.

[0090] According to one embodiment of the present invention, the branched olefin ratio in conduit 58 is controlled to be not less than 1.0 mass%, and preferably not more than 1.5 mass%, 1.7 mass%, 1.9 mass%, 2 mass%, 2.2 mass%, 2.4 mass%, 2.6 mass%, or 2.8 mass%. According to one embodiment of the present invention, the branched olefin ratio in conduit 58 is controlled to be not more than 20 mass%, 15 mass% or more, 10 mass% or more, 9 mass% or more, 8 mass% or more, 7 mass% or more, or 6 mass% or more.

[0091] Meanwhile, the (poly)alkylene glycol monoalkyl ether and the by-product (poly)alkylene glycol dialkyl ether are withdrawn from the bottom of distillation column 44 via conduit 57 and introduced into distillation column 46. While controlling the pressure of distillation column 46, the temperature of the (poly)alkylene glycol monoalkyl ether phase, and the reflux ratio of distillation column 46, the (poly)alkylene glycol monoalkyl ether, which is a component with a low boiling point, is withdrawn as a distillate from the top of distillation column 46 via conduit 62.

[0092] According to one embodiment of the present invention, the top pressure of the distillation column (distillation column 46 in FIG. 3) for obtaining the target (poly)alkylene glycol monoalkyl ether is preferably 10 to 3,000 Pa, 20 to 1,000 Pa, or 30 to 500 Pa. According to one embodiment of the present invention, the bottom temperature of the distillation column (distillation column 46 in FIG. 3) for obtaining the target (poly)alkylene glycol monoalkyl ether is preferably 50 to 350°C, 100 to 300°C, or 150 to 280°C. According to one embodiment of the present invention, the top temperature of the distillation column (distillation column 46 in FIG. 3) for obtaining the target (poly)alkylene glycol monoalkyl ether is preferably 30 to 300°C, 50 to 280°C, or 100 to 250°C. According to one embodiment of the present invention, the reflux ratio of the distillation column (distillation column 46 in FIG. 3) for obtaining the target (poly)alkylene glycol monoalkyl ether is preferably 0.01 to 300, 0.05 to 200, or 0.1 to 100.

[0093] The (poly)alkylene glycol dialkyl ether withdrawn from the bottom of distillation column 46 is fed via conduit 59 and further via raw material supply pipe 50 to continuous tank reactor 41. When impurities such as heavy components accumulate in the (poly)alkylene glycol dialkyl ether phase, the heavy components can be removed by purging a portion of the (poly)alkylene glycol dialkyl ether phase via conduit 60. By repeating this type of flow reaction, the by-product (poly)alkylene glycol dialkyl ether and / or alcohol are converted into (poly)alkylene glycol monoalkyl ether, and (poly)alkylene glycol monoalkyl ether can be obtained highly selectively and efficiently from linear olefins and (poly)alkylene glycol.

[0094] As described above, in order to reduce the concentration of branched olefins in the reactor, it is preferable to install equipment capable of at least partially removing the branched olefins. Specifically, because branched olefins have lower boiling points than linear olefins, installing a distillation column makes it possible to at least partially remove the branched olefins from the olefins. In the process described in Figure 2, the distillation column for removing branched olefins removes the branched olefins as light-boiling components by distillation from the olefin phase separated in the liquid-liquid separator. In the process described in Figure 3, light-boiling components such as olefins and by-product alcohols are first separated from the olefin phase separated in the liquid-liquid separator, and then the branched olefins are removed from the unreacted olefins and by-product alcohols. [Example]

[0095] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto. Experimental examples in which continuous operation was not performed will be explained as reference examples. In the examples, the yield of the product per reaction (per pass through the reactor once) was calculated according to the following formula.

[0096] Yield of (poly)alkylene glycol monoalkyl ether per reaction (per one pass through the reactor) (abbreviated as YE (mol %)) = (number of moles of (poly)alkylene glycol monoalkyl ether produced / number of moles of olefin fed) × 100.

[0097] Reference example 1 The catalyst was a BEA-type zeolite manufactured by Zeolyst (product name: CP 811E, the atomic ratio of Si to Al of the catalyst was 13.0, and the specific surface area was 656 m 2 33.18g of olefins (1.60 mol / g), 270g (1.60 mol) of 1-dodecene, and 298.69g (4.81 mol) of monoethylene glycol were charged into a 1000ml glass reactor equipped with a stirring blade and a reflux condenser. The gas phase was replaced with nitrogen, and then the nitrogen atmosphere was maintained at atmospheric pressure. The raw materials, 1-dodecene and monoethylene glycol, were fully dehydrated, and the catalyst was dried at 300°C for 3 hours before use. The reactor was separated into two phases: an olefin phase and a monoethylene glycol phase, and the catalyst was dispersed in the monoethylene glycol phase.

[0098] The mixture was then heated to 150°C while stirring at 500 rpm, and reacted at that temperature for 1 hour. The reaction mixture was then cooled to room temperature, and the products in the olefin and monoethylene glycol phases were analyzed by gas chromatography. The olefin phase contained primarily unreacted dodecene and monoethylene glycol monododecyl ether, while the monoethylene glycol phase contained primarily unreacted monoethylene glycol, diethylene glycol, and water. The analytical results are shown in Table 1.

[0099] Reference example 2 In Reference Example 1, C 12 The reaction and analysis were carried out in the same manner as in Reference Example 1, except that the branched olefin 2-methyl-1-undecene was used. The results are shown in Table 1.

[0100] Reference example 3 In Reference Example 1, C 12The reaction and analysis were carried out in the same manner as in Reference Example 1, except that dodecene, a mixture of linear olefins (containing 16% by mass of 1-dodecene, with the remaining 84% by mass being a mixture of inner olefins, namely, 2-dodecene, 3-dodecene, 4-dodecene, 5-dodecene, and 6-dodecene), was used. The results are shown in Table 1.

[0101] Reference example 4 reference The reaction and analysis were carried out in the same manner as in Reference Example 1, except that a mixture of C12 branched olefins (a mixture of 2-methyl-1-undecene, 2-methyl-2-undecene, etc.) was used instead of 1-dodecene in Example 1. The results are shown in Table 1.

[0102] [Table 1]

[0103] The above results reveal that the yield of monoethylene glycol monoalkyl ether was lower when a branched olefin was used as the raw material (Reference Examples 2 and 4) than when a linear olefin was used (Reference Examples 1 and 3).

[0104] Example 1 Ethylene glycol monododecyl ether was continuously produced using a continuous reaction apparatus as shown in Figure 2. Continuous tank reactors 11 and 12 were 1000 mL stainless steel continuous tank reactors equipped with agitators (agitation devices 11a and 12a) and band heaters (heating devices 11b and 12b). Continuous tank reactors 11 and 12 were equipped with overflow lines indicated by conduits 21 and 22. The overflow lines were positioned so that the reaction liquid flowed from continuous tank reactor 11 to 12 and then to liquid-liquid separator 13 according to the feed rate of the raw materials supplied via raw material supply pipe 20. A 20-plate Oldershaw distillation column with an inner diameter of 32 mm was used as distillation column 14, and conduit 23 was connected to the seventh plate from the top. A reflux device (not shown) was installed at the top of distillation column 14. A preheater (not shown) was installed near the junction of conduit 23 and distillation column 14, and the reaction liquid supplied from conduit 23 to distillation column 14 was heated. Distillation column 15 was an Oldershaw-type distillation column with 15 plates and an inner diameter of 32 mm, and conduit 27 was connected to the fifth plate from the top of the column. A reflux unit (not shown) was installed at the top of distillation column 15. A preheater (not shown) was installed near the junction of conduit 27 and distillation column 15, and the reaction liquid supplied from conduit 27 to distillation column 15 was heated. Distillation column 16 was a stainless steel packed column with an inner diameter of 20 mm and a height of 500 mm, and was filled with 1.5 mm diameter stainless steel Dixon packing as packing. A reflux unit (not shown) was installed at the top of the column. Conduit 28 was connected to the center of distillation column 16, and a preheater (not shown) was installed near the junction, and the reaction liquid supplied from conduit 28 to distillation column 16 was heated. Further, a pressure reducing device was installed in the distillation columns 14, 15 and 16, and distillation was carried out under reduced pressure.

[0105] Into continuous tank reactors 11 and 12, 268 g (approximately 1.6 mol) of 1-dodecene (branched olefin content: 3 to 5% by mass), 298 g (approximately 4.8 mol) of monoethylene glycol, and a catalyst containing BEA-type zeolite (trade name: VALFOR CP 811BL-25, manufactured by PQ Corporation; the atomic ratio of Si to Al is 12.5, and the specific surface area is 750 m) were placed. 2Each reactor was charged with 32.7 g of 1-dodecene (branched olefin content: 3-5% by mass), and the agitator was operated at 600 rpm. The temperature inside the reactor was then raised to 150°C and maintained at that temperature. The raw materials and catalyst were supplied to the continuous-tank reactor 11 through the raw material supply pipe 20 at a feed rate of 268 g / hr of 1-dodecene (branched olefin content: 3-5% by mass), 298 g / hr of monoethylene glycol, and 32.7 g / hr of catalyst, and the reaction was initiated. The catalyst was supplied as a suspension in monoethylene glycol. The reaction liquid flowing out of the reactor 11 was transferred to the reactor 12 via the conduit 21 to continue the reaction. The reaction liquid flowing out of the reactor 12 was transferred to the liquid-liquid separator 13 via the conduit 22 and separated into a monoethylene glycol phase containing the catalyst and an olefin phase containing monoethylene glycol monododecyl ether. The monoethylene glycol phase was recycled to the continuous-tank reactor 11 via the conduit 24. At this time, 5% by mass of the flow rate was purged from the conduit 25 to the outside of the system.

[0106] On the other hand, the olefin phase was supplied to the distillation column 14 via the conduit 23. The operation conditions of the distillation column 14 were a column top pressure of 1.3 kPa, a column bottom temperature of 100°C, a column top temperature of 80°C, and a reflux ratio of 50. The distillate from the distillation column 14 mainly consisted of branched C 12 The bottoms of the distillation column 14 were fed to the distillation column 15 via a conduit 27. The branched olefin content (dodecenes (C)) of the bottoms of the distillation column 14 fed to the distillation column 15 was 12 linear olefins and C 12 C relative to the mass of the branched olefin 12 The mass of the branched olefin was controlled to 2 to 5 mass %.

[0107] The operating conditions of the distillation column 15 were a column top pressure of 1.3 kPa, a column bottom temperature of 170°C, a column top temperature of 88°C, and a reflux ratio of 0.5. The distillate from the distillation column 15 was mainly unreacted isomerized linear dodecene, which was recycled to the reactor 11 via a conduit 26. The dodecenes (C 12 linear olefins and C 12 C for the sum of the masses of the branched olefins 12It was confirmed that the mass of the branched olefins (branched olefin ratio) was controlled within the range of 3 to 5 mass % 1000 to 3000 hours after the start of operation.

[0108] The bottoms of distillation column 15 were supplied to distillation column 16 via conduit 28. The operating conditions for distillation column 16 were a column top pressure of 270 Pa, a column bottom temperature of 220°C, a column top temperature of 150°C, and a reflux ratio of 0.5. The distillate from distillation column 16 was mainly the target product, monoethylene glycol monododecyl ether, and was recovered as a product via conduit 32. The bottoms of distillation column 16 was mainly monoethylene glycol didodecyl ether, and was recycled to continuous tank reactor 11 via conduit 29. In this example, partial purging of the bottoms of distillation column 16 via conduit 30 was not performed.

[0109] After the reaction starts, the amounts of new (fresh) raw materials (1-dodecene, monoethylene glycol) and new or regenerated catalyst fed from raw material feed pipe 20 are adjusted in accordance with the flow rates of the recovered raw materials and catalyst recycled through conduits 24, 26, and 29, so that the raw material composition fed to continuous tank reactor 11 is such that the molar ratio of monoethylene glycol to dodecenes is 3 / 1, the catalyst amount is 10 mass% in the monoethylene glycol phase, and the feed liquid flow rate is such that the liquid hourly space time (LHSV) in continuous tank reactor 11 is 1 hr -1 It was controlled so that

[0110] From 1000 to 3000 hours after the start of operation of the continuous reactor under the above operating conditions, the branched olefin ratio of the dodecenes supplied to reactor 11 was controlled to 3 to 5 mass% throughout the operation. The yield (YE (mol%)) of monoethylene glycol monododecyl ether recovered from conduit 32 via reactor 12 relative to the dodecenes supplied to reactor 11 was 10.2% at 1000 hours and 10.0% at 3000 hours, remaining within a range of 10% ± 1.2% from 1000 to 3000 hours. During this period, the overall process yield of the target monoethylene glycol monododecyl ether relative to 1-dodecene fed from raw material supply pipe 20 (olefin utilization efficiency) was 88 ± 2 mol%. The yield of monoethylene glycol monododecyl ether per unit time was 323 g / hr.

[0111] Comparative Example 1 In Example 1, distillation column 14 was operated under the conditions of Example 1 for 1000 hours, and then the operation of distillation column 14 was stopped (using distillation column 14 simply as a bypass to distillation column 15), and a similar experiment was performed.

[0112] Dodecenes (C 12 linear olefins and C 12 C for the sum of the masses of the branched olefins 12 The mass of branched olefins (branched olefin ratio) increased over time from 4.5% by mass to 30% by mass between 1000 and 2000 hours after the start of operation, and could not be controlled so as not to exceed 20% by mass.

[0113] Furthermore, from 1,000 to 2,000 hours after the start of operation of the continuous reactor under the above operating conditions, the branched olefin ratio of the dodecenes supplied to reactor 11 increased over time from 4.5% by mass to 30% by mass. Furthermore, the yield (YE (mol%)) of monoethylene glycol monododecyl ether recovered from conduit 32 via reactor 12 relative to the dodecenes supplied to reactor 11 was 10.0% at 1,000 hours and 6.4% at 2,000 hours, clearly decreasing between 1,000 and 2,000 hours. Because the reactor was operated to maintain the residence time of the reaction liquid and the liquid level of the reaction liquid in the reactor, the amount of raw material introduced from raw material supply pipe 20 decreased compared to the initial amount, and the hourly feed rate at 2,000 hours decreased to approximately two-thirds of the initial amount (180 g / hr of 1-dodecene). The yield of the target monoethylene glycol monododecyl ether throughout the process (olefin utilization efficiency) relative to 1-dodecene fed from the raw material supply pipe 20 was 89 mol% at the time point of 2000 hours. In addition, the yield of monoethylene glycol monododecyl ether per unit time at the time point of 2000 hours was 220 g / hr.

[0114] Example 2 Ethylene glycol monododecyl ether was continuously produced using a continuous reaction apparatus as shown in FIG. 3. Continuous tank reactors 41 and 42 were 1000 mL stainless steel continuous tank reactors equipped with agitators (agitation devices 41a and 42a) and band heaters (heating devices 41b and 42b). Overflow lines indicated by conduits 51 and 52 were installed in the continuous tank reactors 41 and 42. The overflow lines were positioned so that the reaction liquid flowed from the continuous tank reactor 41 to the continuous tank reactor 42 and then to the liquid-liquid separator 43 according to the feed rate of the raw materials supplied via the raw material supply pipe 50. A 20-plate Oldershaw distillation column with an inner diameter of 32 mm was used as the distillation column 44, and conduit 53 was connected to the seventh plate from the top. A reflux unit (not shown) was installed at the top of the distillation column 44. A preheater (not shown) was installed near the junction between conduit 53 and distillation column 44, and the reaction liquid supplied from conduit 53 to distillation column 44 was heated. Distillation column 45 was an Oldershaw-type distillation column with 15 plates and an inner diameter of 32 mm, and conduit 56 was connected to the fifth plate from the top of the column. A reflux unit (not shown) was installed at the top of distillation column 45. A preheater (not shown) was installed near the junction between conduit 56 and distillation column 45, and the reaction liquid supplied from conduit 56 to distillation column 45 was heated. Distillation column 46 was a stainless steel packed column with an inner diameter of 20 mm and a height of 500 mm, and was filled with 1.5 mm diameter stainless steel Dixon packing as packing. A reflux unit (not shown) was installed at the top of the column. Conduit 57 was connected to the center of distillation column 46, and a preheater (not shown) was installed near the junction, and the reaction liquid supplied from conduit 57 to distillation column 46 was heated. Further, pressure reducing devices were installed in the distillation columns 44, 45 and 46, and distillation was carried out under reduced pressure.

[0115] Into continuous tank reactors 41 and 42, 268 g of 1-dodecene (branched olefin content: 3% by mass to 5% by mass), 298 g of monoethylene glycol, and a catalyst, BEA-type zeolite (trade name: VALFOR CP 811BL-25, manufactured by PQ Corporation; the atomic ratio of Si to Al is 12.5, and the specific surface area is 750 m) were placed. 2Each reactor was charged with 32.7 g of 1-dodecene (branched olefin content: 3% to 5% by mass), and the agitator was operated at 600 rpm. The temperature inside the reactor was then raised to 150°C and maintained at that temperature. The raw materials and catalyst were supplied to continuous-tank reactor 41 through raw material supply pipe 50 at a feed rate of 268 g / hr of 1-dodecene (branched olefin content: 3% to 5% by mass), 298 g / hr of monoethylene glycol, and 32.7 g / hr of catalyst, and the reaction was initiated. The catalyst was supplied as a suspension in monoethylene glycol. The reaction liquid was transferred to liquid-liquid separator 43 via conduit 52 and separated into a monoethylene glycol phase containing the catalyst and an olefin phase containing monoethylene glycol monododecyl ether. The monoethylene glycol phase was recycled to continuous-tank reactor 41 via conduit 54. 5% by mass of the flow rate was purged from conduit 55 to the system.

[0116] On the other hand, the olefin phase was supplied to the distillation column 44 via the conduit 53. The operation conditions of the distillation column 44 were a column top pressure of 1.5 kPa, a column bottom temperature of 100°C, a column top temperature of 90°C, and a reflux ratio of 0.5. The distillate from the distillation column 44 mainly consisted of branched C 12 The distillate from distillation column 44 consisted mainly of branched C olefins and linear dodecene, and was supplied to distillation column 45 via conduit 56. The bottoms from distillation column 44 were supplied to distillation column 46 via conduit 57. The operating conditions for distillation column 45 were a column top pressure of 1.0 kPa, a column bottom temperature of 80°C, a column top temperature of 70°C, and a reflux ratio of 50. The distillate from distillation column 45 consisted mainly of branched C olefins and linear dodecene. 12 The distillate from the distillation column 45 was recycled to the reactor 41 through the conduit 58. The dodecenes (C 12 linear olefins and C 12 C for the sum of the masses of the branched olefins 12 It was confirmed that the mass of the branched olefins (branched olefin ratio) was controlled within the range of 2 to 5 mass % 1000 to 2000 hours after the start of operation.

[0117] The operating conditions for distillation column 46 were a column top pressure of 400 Pa, a column bottom temperature of 240°C, a column top temperature of 140°C, and a reflux ratio of 0.5. The distillate from distillation column 46 was mainly the target product, monoethylene glycol monododecyl ether, and was recovered as a product via conduit 62. The bottoms from distillation column 46 was mainly monoethylene glycol didodecyl ether, and was recycled to continuous tank reactor 41 via conduit 59. In this example, partial purging of the bottoms from distillation column 46 via conduit 60 was not performed.

[0118] After the reaction starts, the amounts of new raw materials (1-dodecene, monoethylene glycol) and new or regenerated catalyst supplied from raw material supply pipe 50 are adjusted in accordance with the flow rates of the recovered raw materials and catalyst recycled through conduits 54, 58, and 59, so that the raw material composition supplied to continuous tank reactor 41 is such that the molar ratio of monoethylene glycol / dodecenes is 3 / 1, the catalyst amount is 10 mass% in the monoethylene glycol phase, and the liquid supply flow rate is such that the liquid hourly space time (LHSV) in continuous tank reactor 41 is 1 hr -1 It was controlled so that

[0119] Furthermore, from 1000 to 2000 hours after the start of operation of the continuous reactor under the above operating conditions, the branched olefin ratio in the dodecenes supplied to reactor 41 was controlled to 2 to 5 mass% throughout the operation. The yield (YE (mol%)) of monoethylene glycol monododecyl ether recovered from conduit 62 via reactor 42 relative to the dodecenes supplied to reactor 41 was 9.9% at 1000 hours and 10.0% at 2000 hours, remaining within a range of 10% ± 1.1% from 1000 to 3000 hours. The overall process yield of the target monoethylene glycol monododecyl ether relative to 1-dodecene fed from raw material supply pipe 50 (olefin utilization efficiency) was 87 ± 2 mol%. The yield of monoethylene glycol monododecyl ether per unit time was 320 g / hr.

[0120] Example 3 In Example 2, the distillation column 45 was operated under the conditions of Example 2 for up to 1000 hours, and then the top temperature of the distillation column 45 was set to 80°C in order to further reduce the branched olefin ratio, thereby reducing the branched olefin ratio in the dodecenes supplied to the reactor 41 to a level lower than that in Example 2. The experiment was carried out in the same manner as in Example 2. 12 linear olefins and C 12 C for the sum of the masses of the branched olefins 12 The mass of the branched olefins (branched olefin ratio) decreased over time from 4.0 mass % to 1.5 mass % between 1000 and 1500 hours after the start of operation.

[0121] Furthermore, from 1000 hours to 1500 hours after the start of operation of the continuous reactor under the above operating conditions, the branched olefin ratio in the dodecenes supplied to reactor 41 decreased over time from 4.0 mass% to 1.7 mass%. Furthermore, the yield (YE (mol%)) of monoethylene glycol monododecyl ether recovered from conduit 62 via reactor 42 relative to the dodecenes supplied to reactor 41 was 9.9% at 1000 hours and 10.6% at 1500 hours, showing a slight improvement between 1000 hours and 1500 hours.

[0122] However, since the raw material olefins were also removed together with the branched olefins, the olefin utilization efficiency decreased, and the yield of the target monoethylene glycol monododecyl ether (olefin utilization efficiency) in the entire process relative to the total 1-dodecene fed from the raw material supply pipe 50 was 81 mol% at the time point of 1500 hours. In addition, the yield of monoethylene glycol monododecyl ether per unit time was 290 g / hr.

[0123] As described above, it is clear that it is preferable to control the branched olefin ratio in the recovered raw material so that it does not become 1.5 mass % or less.

[0124] From the above examples and comparative examples, it is clear that increasing the branched olefin concentration reduces the yield of monoethylene glycol monododecyl ether before and after the reactor, and although the yield of the entire process (olefin utilization efficiency) remains almost unchanged, the yield per hour drops significantly. On the other hand, decreasing the branched olefin concentration increases the yield of monoethylene glycol monododecyl ether before and after the reactor, but the loss of raw materials in distillation is large, reducing the yield of the entire process (olefin utilization efficiency), and so the yield per hour also drops.

[0125] Reference example 5 The catalyst used was the same as in Example 1, which had been reacted for 3,000 hours and then deteriorated. Except for this, the reaction and analysis were carried out in the same manner as in Reference Example 3. The results are shown in Table 2.

[0126] Reference example 6 The catalyst used was the same as in Example 1, which had been reacted for 3,000 hours and then deteriorated. Except for this, the reaction and analysis were carried out in the same manner as in Reference Example 4. The results are shown in Table 2.

[0127] [Table 2]

[0128] From the above results, when the reaction was carried out using a deteriorated catalyst and a branched olefin as the raw material (Reference Example 6), the yield of monoethylene glycol monoalkyl ether per reaction was clearly lower than when the reaction was carried out using a deteriorated catalyst and a linear olefin as the raw material (Reference Example 5). In particular, when Reference Example 4 and Reference Example 6 are compared, the decrease in yield per reaction due to catalyst deterioration is very severe when a branched olefin is used as the raw material, and it has become clear that the decrease in yield per reaction of monoethylene glycol monododecyl ether (per pass through the reactor once) in Comparative Example 1 is almost entirely due to the branched olefin. [Industrial Applicability]

[0129] The (poly)alkylene glycol monoalkyl ether obtained by the present invention is useful as a raw material for surfactants, and the present invention can provide a method for producing a (poly)alkylene glycol monoalkyl ether that is useful for reducing resource and energy consumption from the perspectives of reducing the burden on the global environment, protecting resources, achieving carbon neutrality, and achieving the SDGs (Sustainable Development Goals), etc. [Explanation of symbols]

[0130] 1: Batch reactor 1a: Stirring device 1b: Heating device 2: Distillation tower 3: Conduit 4: Raw material supply pipe 5, 6: Extraction pipe 11, 12, 41, 42: Continuous tank reactor 11a, 12a, 41a, 42a: Stirring device 11b, 12b, 41b, 42b: Heating device 13, 43: Liquid-liquid separation device 14, 15, 16, 44, 45, 46: Distillation tower 20, 50: Raw material supply pipe 21~32, 51~62: Conduit.

[0131] This application is based on Japanese Patent Application No. 2022-169504, filed on October 21, 2022, the disclosure of which is incorporated by reference in its entirety.

Claims

1. A method for producing a (poly)alkylene glycol monoalkyl ether, comprising reacting an olefin with a (poly)alkylene glycol in the presence of a catalyst in a reactor, the method comprising: and recovering at least a portion of the raw materials used in the production and reusing them as raw materials; At least one of the recovered feedstocks comprises olefins; and controlling the mass of the branched olefins relative to the sum of the masses of the branched olefins and linear olefins contained in the recovered raw material so that it is not more than 10 mass% and not more than 1.5 mass%.

2. The method according to claim 1, wherein the olefin has 6 to 20 carbon atoms.

3. 3. The method of claim 2, wherein the recovered feedstock comprises olefins from which branched olefins have been separated by distillation.

4. 3. The method according to claim 1 or 2, wherein at least one of the recovered raw materials comprises a (poly)alkylene glycol.

5. The method according to claim 2 , wherein the catalyst is a solid acid catalyst.

6. 6. The method according to claim 5, wherein a crystalline metallosilicate is used as the solid acid catalyst.

7. The method according to claim 2 or 5, wherein the (poly)alkylene glycol is monoethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, monopropylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,3-propanediol, 1,2-butanediol, 2,3-butanediol, 1,4-butanediol, 1,6-hexanediol, or 1,4-cyclohexanemethanediol.

8. The method according to claim 2 or 6, wherein the (poly)alkylene glycol is monoethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, monopropylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,3-propanediol, 1,2-butanediol, 2,3-butanediol, 1,4-butanediol, 1,6-hexanediol, or 1,4-cyclohexanemethanediol.

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