JP2013067564A - Method for producing carboxylate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably remove noble metal-supporting activated carbon contained in a reaction liquid in a short time, in a method for producing a polyoxyalkylene alkyl ether carboxylate.SOLUTION: An oxygen-containing gas is brought into contact with slurry containing a polyoxyalkylene alkyl ether, a noble metal-supporting catalyst whose carrier is activated carbon, and water, whereby the polyoxyalkylene alkyl ether is oxidized to generate a polyoxyalkylene alkyl ether carboxylate. The resulting reaction liquid containing the generated polyoxyalkylene alkyl ether carboxylate is filtered using a filter medium made of a sulfonic polymer to thereby separate the noble metal-supporting catalyst contained in the reaction liquid.

Description

  The present invention relates to a method for producing a polyoxyalkylene alkyl ether carboxylic acid and a salt thereof.

  Polyoxyalkylene alkyl ether carboxylic acids and salts thereof are compounds having a carboxyl group at the end of polyoxyalkylene alkyl ether, and are excellent in foaming power and emulsifying power, and are cosmetics, emulsifiers, solubilizers, dispersants, gels. It is known as a surfactant that can be used in an agent, a cleaning base and the like. The properties of polyoxyalkylene alkyl ether carboxylic acids and salts thereof can be adjusted by changing the pH, are excellent in hard water resistance, and the aqueous solution is stable against various polyvalent metal ions such as aluminum. In addition, since the action on the skin is mild and the enzyme inhibitory property is low, it is expected to be applied in various other applications.

  Various methods for producing polyoxyalkylene alkyl ether carboxylic acids or salts thereof are known, and one of them is a method in which polyoxyalkylene alkyl ether is oxidized with oxygen in the presence of a noble metal-supported catalyst having a noble metal supported on a carrier. Known (for example, Patent Documents 1 to 3).

  Patent Document 4 discloses that the powder derived from the activated carbon filter can be removed from the water after the PCB removal treatment with a polysulfone membrane filter.

JP 58-46036 A JP 60-172942 A Japanese Unexamined Patent Publication No. Sho 62-198641 JP 2008-29995 A

  In general, a noble metal-supported catalyst is expensive, and thus it is recovered after being recovered after the reaction. Moreover, in order to be able to use the polyoxyalkylene alkyl ether carboxylic acid or salt thereof produced in the production process as a product, it is necessary to remove the noble metal-supported catalyst and the fine particles of the substance derived therefrom in a single time and reliably. . It is because it becomes possible to use it as a product by removing the fine powder, and the delay of the manufacturing process can be prevented by performing it in a short time.

  However, conventionally, it has not been known what means can be used to reliably remove fine powder in a short time.

  An object of the present invention is to remove a noble metal-supported catalyst contained in a reaction solution in a short time with certainty in a method for producing a polyoxyalkylene alkyl ether carboxylic acid or a salt thereof excellent in foaming power and emulsifying power. .

  The present invention relates to a polyoxyalkylene alkyl ether excellent in foaming power and emulsifying power, a noble metal supported catalyst using activated carbon as a carrier, and a polyoxyalkylene alkyl ether by contacting a gas containing oxygen with a slurry containing water. Is oxidized to produce a polyoxyalkylene alkyl ether carboxylate, and then the reaction solution containing the produced polyoxyalkylene alkyl ether carboxylic acid or salt thereof is filtered using a sulfone polymer filter medium. By this, the process for isolate | separating the noble metal carrying | support catalyst contained in a reaction liquid is provided, The manufacturing method of polyoxyalkylene alkyl ether carboxylic acid or its salt is provided.

  According to the present invention, the reaction solution containing the produced polyoxyalkylene alkyl ether carboxylic acid or salt thereof is filtered using a filter medium composed of a sulfone polymer, so that it is contained in the reaction solution in a short time and reliably. The noble metal supported catalyst can be separated and removed.

  Hereinafter, embodiments will be described in detail. In addition, this embodiment includes both the case where a polyoxyalkylene alkyl ether carboxylic acid is produced under acidic conditions and the case where a polyoxyalkylene alkyl ether carboxylate is produced under alkaline conditions.

  In the method for producing a polyoxyalkylene alkyl ether carboxylic acid or salt thereof according to this embodiment, a gas containing oxygen in a slurry containing polyoxyalkylene alkyl ether, a noble metal-supported catalyst using activated carbon as a carrier, and water (hereinafter “ The oxygen-containing gas is contacted with oxygen to oxidize the polyoxyalkylene alkyl ether to produce a polyoxyalkylene alkyl ether carboxylic acid or a salt thereof, and then the produced polyoxyalkylene alkyl ether carboxylic acid or a salt thereof. The reaction solution containing a salt is subjected to microfiltration using a filter medium made of a sulfone polymer to separate and remove the noble metal-supported catalyst contained in the reaction solution.

  According to the above method, the reaction solution containing the produced polyoxyalkylene alkyl ether carboxylic acid or salt thereof is precisely filtered using a filter medium made of a sulfone polymer, so that the reaction solution is contained in a short time and surely. The noble metal supported catalyst can be separated and removed.

[Reaction process]
In the method for producing a polyoxyalkylene alkyl ether carboxylic acid or salt thereof according to the present embodiment, first, an oxygen-containing gas is brought into contact with a slurry containing polyoxyalkylene alkyl ether, a noble metal-supported catalyst, and water as reaction raw materials. The polyoxyalkylene alkyl ether is oxidized with oxygen to produce a polyoxyalkylene alkyl ether carboxylic acid or a salt thereof.

(slurry)
<Reaction raw materials and reaction products>
The slurry contains polyoxyalkylene alkyl ether as a reaction raw material.

  The polyoxyalkylene alkyl ether is preferably a compound represented by the following general formula (I).

RO- (AO) _n -H (I)
[Wherein, R is a hydrocarbon group having 4 to 30 carbon atoms, AO is an alkyleneoxy group having 2 to 4 carbon atoms, and n is an average added mole number of AO, which is a number of 1 to 100. ]
The structure in the formula can be appropriately selected according to the performance, use, etc. of the target carboxylic acid or salt thereof.

  R has 4 to 30 carbon atoms, but is preferably 8 to 22 and more preferably 10 to 18 from the viewpoint of separating the noble metal-supported catalyst contained in the reaction solution of the carboxylic acid or its salt. Preferably, it is 12-14. Examples of the hydrocarbon group for R include an alkyl group and an alkenyl group. R may be linear or branched, and may be primary or secondary.

  R is preferably a linear or branched primary or secondary alkyl group or alkenyl group from the viewpoint of separating the noble metal-supported catalyst contained in the reaction solution, and a linear primary or secondary alkyl group. Alternatively, an alkenyl group is more preferable, a linear primary alkyl group or alkenyl group is further preferable, and a linear primary alkyl group is particularly preferable.

  AO is an alkyleneoxy group having 2 to 4 carbon atoms, but from the viewpoint of versatility and economy as a material, it is preferably an ethyleneoxy group having 2 carbon atoms, and 80 mol% or more of all AOs. More preferably, it is an ethyleneoxy group.

  Although n is a number from 1 to 100, it is preferably 1 to 20 and more preferably 2 to 10 from the viewpoint of separating the noble metal-supported catalyst contained in the reaction solution.

  The slurry may contain only a single kind of polyoxyalkylene alkyl ether or may contain a plurality of kinds of polyoxyalkylene alkyl ether.

  The concentration of the polyoxyalkylene alkyl ether in the slurry is preferably 1% by mass or more, more preferably 5% by mass or more, and more preferably 10% by mass or more from the viewpoint of improving production efficiency. On the other hand, it is preferably 40% by mass or less, more preferably 35% by mass or less, and still more preferably 30% by mass or less from the viewpoint that the handleability is good.

  Specifically, the concentration of the polyoxyalkylene alkyl ether in the slurry is preferably 1 to 40% by mass, more preferably 5 to 35% by mass, and still more preferably 10 to 30% by mass.

  The polyoxyalkylene alkyl ether carboxylic acid, which is a reaction product produced using the compound represented by the general formula (I) as the polyoxyalkylene alkyl ether, can have a structure represented by the following general formula (II).

RO- (AO) _n-1 -A'-COOH (II)
[Wherein R, AO and n represent the same meaning as in general formula (I), and A ′ represents an alkylene group having 1 to 3 carbon atoms]
In addition, a polyoxyalkylene alkyl ether carboxylate, which is a reaction product produced using a compound represented by the general formula (I) as a polyoxyalkylene alkyl ether, may have a structure represented by the following general formula (III). it can.

{RO- (AO) _n-1 -A'-COO} _m M (III)
[Wherein, R, AO and n represent the same meaning as in formula (I), A ′ represents an alkylene group having 1 to 3 carbon atoms, M represents a cation, and m represents a valence of M. ]
Preferred embodiments of R, AO and n in the general formulas (II) and (III) are the same as those in the general formula (I).

  A ′ is an alkylene group having 1 to 3 carbon atoms, but the terminal —AO— in formula (I) is oxidized to form a structure of —A′—COO—. It is one less than the carbon number of the terminal -AO- in (I).

  Examples of M that is a cation include alkali metal ions, alkaline earth metal ions, and ammonium ions. Examples of alkali metal ions include lithium ions, sodium ions, potassium ions, and the like. Examples of alkaline earth metal ions include magnesium ions and calcium ions. M, which is a cation, is more preferably an alkali metal ion from the viewpoint that the slurry exhibits an appropriate viscosity during production and from the viewpoint of simplicity of the production process. Among the alkali metal ions, sodium ions and potassium ions are preferable, and sodium ions are more preferable from the viewpoint of reducing the manufacturing cost.

<Precious metal supported catalyst>
The slurry contains activated carbon supporting a noble metal that is a catalyst as a noble metal-supported catalyst.

  From the viewpoint of obtaining a high yield of polyoxyalkylene alkyl ether carboxylic acid or a salt thereof, the noble metal as a catalyst is one or more elements selected from platinum group elements, specifically ruthenium, rhodium, It is preferable to contain one or more elements selected from palladium, osmium, iridium, and platinum, and it is particularly preferable to contain one or more elements selected from palladium and platinum.

  When the noble metal contains one or more elements selected from platinum group elements (hereinafter referred to as “catalyst first component”), the noble metal-supported catalyst is further composed of tin, bismuth, selenium, tellurium, and antimony as catalyst components. It is preferable to contain one or more selected elements (hereinafter referred to as “catalyst second component”).

  When the noble metal-supported catalyst contains the catalyst first component and the second component, the noble metal-supported catalyst further contains one or more elements selected from rare earth elements (hereinafter referred to as “catalyst third component”) as the catalyst component. It is preferable.

  The carrier on which the catalyst component containing the noble metal of the first catalyst component is supported is activated carbon having high durability against acidic substances or alkaline substances. As the activated carbon, one produced by a known method using sawdust, wood chips, charcoal, coconut shell charcoal, coal, peat charcoal, or the like as a raw material can be used.

  From the viewpoint that a high yield of polyoxyalkylene alkyl ether carboxylic acid or a salt thereof can be obtained, the amount of the noble metal supported as the first component of the catalyst in the noble metal supported catalyst is 0.1 to 20 of the total noble metal supported catalyst. The content is preferably mass%, more preferably 0.5 to 15 mass%, still more preferably 1 to 10 mass%.

  The noble metal-supported catalyst can be produced by a known method disclosed in JP-A-62-269746. For example, an aqueous solution of a compound containing a catalyst first component (palladium chloride, chloroplatinic acid, etc.), an aqueous solution of a compound containing a catalyst second component (bismuth chloride, antimony pentachloride, etc.) as needed, and a catalyst as needed It can be produced by a method in which each catalyst component is adsorbed on activated carbon as a carrier in each solution of an aqueous solution of a compound containing the third component (cerium chloride, lanthanum chloride, etc.), and then the catalyst component is subjected to reduction treatment.

  The content of the noble metal of the first catalyst component in the slurry is preferably 0.001 to 2.0% by mass with respect to the content of the polyoxyalkylene alkyl ether that is the reaction raw material, and 0.01 to 1.5%. It is more preferable to set it as the mass%, and it is still more preferable to set it as 0.02-1.3 mass%. In addition, when a some element is included as a catalyst 1st component, content of the said noble metal is those total amounts.

  The content of the noble metal-supported catalyst in the slurry is preferably 0.1% by mass or more, more preferably 0.5% by mass or more from the viewpoint of increasing the reactivity with respect to the polyoxyalkylene alkyl ether. From the viewpoint of property, it is preferably 20% by mass or less, and more preferably 10% by mass or less.

  Specifically, the content of the noble metal-supported catalyst in the slurry is preferably 0.1 to 20% by mass, and more preferably 0.5 to 10% by mass.

<Water>
The slurry contains water as a liquid.

  The content of water in the slurry is preferably 0.1 to 100 times by mass with respect to the content of the polyoxyalkylene alkyl ether, from the viewpoint that high reactivity is obtained and handleability is good. It is more preferable to set it as 5-50 mass times, and it is still more preferable to set it as 1-20 mass times.

  Note that the slurry does not reduce the reactivity, and liquid organic solvents such as lower alcohols such as ethanol as long as it does not hinder foaming after blending with a cleaning agent and the removal of the noble metal supported catalyst contained in the reaction solution. You may contain as a liquid used as a phase.

<Alkaline substances>
When producing a polyoxyalkylene alkyl ether carboxylate under alkaline conditions, the slurry preferably contains an alkaline substance. The oxygen oxidation of the polyoxyalkylene alkyl ether is preferably performed in the presence of an alkaline substance.

  Examples of the alkaline substance include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; alkali metal carbonates such as sodium carbonate and potassium carbonate. Of these, alkali metal hydroxides are preferable from the viewpoint that high reactivity can be obtained. Among them, sodium hydroxide and potassium hydroxide are preferable, and sodium hydroxide is more preferable.

  The slurry may contain only a single type of alkaline substance or a plurality of types of alkaline substance.

  The content of the alkaline substance in the slurry is preferably an amount such that the pH of the slurry is 7 to 14, more preferably 9 to 14, and still more preferably 11 to 14.

<Optional component>
The slurry may previously contain polyoxyalkylene alkyl ether carboxylic acid and / or a salt thereof, which is an oxidation reaction product of polyoxyalkylene alkyl ether, and does not decrease the reactivity and is contained in the reaction solution. In addition, an organic solvent, an inorganic salt, a polymer, and the like may be contained as long as the separation and removal of the noble metal-supported catalyst is not inhibited.

<Liquid properties>
The slurry preferably has a dissolved oxygen concentration of less than 3.0 mg / L, more preferably 1.0 mg / L or less, before the oxidation reaction, that is, at the start of supplying the oxygen-containing gas. The dissolved oxygen concentration of the slurry is measured by immersing the measuring unit sensor in the slurry using various measuring devices based on the measurement principle of the diaphragm electrode type (polarographic type, galvanic cell type) and fluorescent type (the same applies hereinafter).

Slurry is a non-Newtonian pseudoplastic fluid whose viscosity varies with reaction rate and temperature and whose apparent viscosity decreases as the applied shear rate increases. For this reason, the viscosity of the slurry before starting the reaction (before supplying oxygen) affects the reactivity, that is, the reaction end time. Therefore, from the viewpoint of productivity and also from the viewpoint of quality such as hue, the viscosity of the slurry is preferably 1 to 10000 mPa · s at the time before starting the reaction (time before supplying oxygen), It is more preferably 10 to 5000 mPa · s, and further preferably 100 to 1000 mPa · s. The viscosity of the slurry is measured as a static viscosity using a rheometer (for example, ARES-100TNI manufactured by TAinstrument) with a Couette of 34 mm and a condition of 70 ° C. and a shear rate of 1 s ⁻¹ .

  When the polyoxyalkylene alkyl ether carboxylate is produced, the pH of the slurry is preferably 7 to 14 and more preferably 9 to 14 as described above from the viewpoint of quality such as reactivity and hue. More preferably, it is 11-14.

(Oxidation reaction)
<Oxygen-containing gas>
From the viewpoint of increasing the reaction rate, the oxygen concentration in the oxygen-containing gas is preferably 20% by volume or more, more preferably 80% by volume or more, still more preferably 90% by volume or more, and 95% by volume. % Or more is more preferable, and 100% by volume is particularly preferable.

  Examples of gases other than oxygen in the oxygen-containing gas include noble gases such as nitrogen and argon which are inert to the oxidation reaction of polyoxyalkylene alkyl ether. Moreover, the atmosphere typically includes the oxygen-containing gas.

<Means for contacting oxygen-containing gas with slurry>
The contact of the oxygen-containing gas with the slurry is performed in, for example, a stirred tank reactor. Specific examples of the means include blowing oxygen-containing gas (air, etc.) into the slurry, and oxygen content into the slurry by stirring. Examples include entrainment of gas and contact at the free interface between the slurry and the oxygen-containing gas. As the means for contacting the oxygen-containing gas with the slurry, only one of the above may be employed, or a plurality may be employed in combination.

  The means for contacting the oxygen-containing gas with the slurry is preferably continuous or intermittent blowing of the oxygen-containing gas into the slurry from the viewpoint of suppressing a decrease in the reaction pressure.

  The oxygen-containing gas is blown into the slurry from an outlet of a gas blowing pipe installed in the slurry. Examples of the outlet of the gas blowing tube include a single hole nozzle, a porous nozzle, and a ring nozzle.

  From the viewpoint of productivity, the blowing rate of the oxygen-containing gas into the slurry is preferably set so that the oxygen supply rate is 1 mol% / h or more with respect to the number of moles of the charged polyoxyalkylene alkyl ether, From the viewpoint of maintaining the reaction rate by suppressing the deactivation of the catalyst by oxygen, it is more preferable to set it to be 5 mol% / h or more, and even more preferable to set it to be 10 mol% / h or more. The oxygen supply rate is preferably set to 50 mol% / h or less, more preferably 30 mol% / h or less, relative to the number of moles of the charged polyoxyalkylene alkyl ether, More preferably, it is set to 20 mol% / h or less.

  Specifically, the blowing rate of the oxygen-containing gas into the slurry is preferably set so that the oxygen supply rate is 1 to 50 mol% / h with respect to the number of moles of the charged polyoxyalkylene alkyl ether, It is more preferable to set it to be 5 to 30 mol% / h, and it is even more preferable to set it to be 10 to 20 mol% / h.

In the case of entraining the oxygen-containing gas into the slurry by stirring, the oxygen supply rate can be set by the PV value. From the viewpoint of improving the stirring efficiency and increasing the reaction rate, the PV value is preferably set to 0.1 or higher, more preferably set to 0.2 or higher, and set to 0.5 or higher. Is more preferable. Here, the PV value means the power required for stirring per unit volume of the slurry, and the stirring power of the stirrer is subtracted from the friction loss due to stirring, that is, the power of stirring (kW) that is truly transmitted to the slurry / volume of the slurry. Defined by (m ³ ).

  Examples of the stirring blade used for stirring include a paddle blade, a turbine blade, and a propeller blade. Examples of the paddle wing include a wing configured to include a flat plate member and an anchor wing. In the paddle blade configured to include a flat plate member, the vertical cross section (S1) of the vertical plane of the region occupied by the liquid phase in the stirred tank reactor and the direction perpendicular to the rotation axis of the shaft of the stirred blade The ratio (S2 / S1) to the maximum projected area (S2) viewed from the viewpoint of efficiently producing a polyoxyalkylene alkyl ether carboxylate or a salt thereof is preferably 0.10 to 0.90, More preferably, it is 0.20 to 0.70. Examples of commercially available stirring blades having such a configuration include, for example, trade name manufactured by Sumitomo Heavy Industries, Ltd .: Max Blend, product name manufactured by Shinko Environmental Solution Co., Ltd .: full zone, product name manufactured by Satake Chemical Machinery Co., Ltd .: Supermix MR203 etc. are mentioned.

  From the viewpoint of maintaining the reaction rate by suppressing the deactivation of the catalyst due to oxygen, the rate of increase of the reaction rate represented by the following formula (A) per hour is the rate at which the oxygen-containing gas is blown into the slurry and the PV value. Is preferably set to be 50% or less, more preferably 40% or less, and still more preferably 30% or less.

Reaction rate (%) = total molar concentration of polyoxyalkylene alkyl ether carboxylic acid and its salt (mol / L) / (molar concentration of polyoxyalkylene alkyl ether (mol / L) + polyoxyalkylene alkyl ether carboxylic acid and its Total molar concentration of salt (mol / L)) (A)
The dissolved oxygen concentration in the slurry during the oxygen oxidation of the polyoxyalkylene alkyl ether is preferably maintained at 0 mg / L or more from the viewpoint of increasing the reactivity with respect to the polyoxyalkylene alkyl ether, and is preferably 0.1 mg / L or more. More preferably, it is more preferably maintained at 0.2 mg / L or more, and particularly preferably maintained at 0.3 mg / L or more. On the other hand, 1.0 mg / L from the viewpoint of suppressing slurry foaming. It is preferable to maintain below, it is more preferable to maintain below 0.9 mg / L, It is still more preferable to maintain below 0.8 mg / L, It is especially preferable to maintain below 0.7 mg / L. The management control of the dissolved oxygen concentration in the slurry is performed by measuring the dissolved oxygen concentration of the slurry over time using a measuring device and increasing or decreasing the supply amount of the oxygen-containing gas to the slurry based on the measurement result. be able to.

  Specifically, the dissolved oxygen concentration in the slurry during the oxygen oxidation of the polyoxyalkylene alkyl ether is preferably maintained at 0 to 1.0 mg / L, and is preferably maintained at 0.1 to 0.9 mg / L. More preferably, it is more preferable to maintain at 0.2-0.8 mg / L, and it is especially preferable to maintain at 0.3-0.7 mg / L.

  The reaction temperature for the oxygen oxidation of the polyoxyalkylene alkyl ether is preferably 20 to 100 ° C, more preferably 30 to 90 ° C, still more preferably 40 to 80 ° C.

  The reaction pressure is preferably 0 (normal pressure) to 1.0 MPa as the gauge pressure from the viewpoint of increasing the solubility of oxygen in the slurry and considering the pressure resistance of the apparatus, and 0 (normal pressure) to 0. The pressure is more preferably 5 MPa, and further preferably 0 (normal pressure) to 0.3 MPa.

  In addition, for example, the charging of the polyoxyalkylene alkyl ether, the noble metal-supported catalyst and the water into the stirred tank reactor may be performed continuously or intermittently. When the alkaline substance is charged, it is preferably charged as an aqueous solution, and it is preferable to charge continuously or intermittently so that the pH of the slurry maintains a predetermined value.

  In the method for producing a polyoxyalkylene alkyl ether carboxylic acid or a salt thereof according to the present embodiment, the polyoxyalkylene alkyl ether carboxylic acid or a salt thereof is represented by the general formula (A) from the viewpoint of excellent performance as a cleaning substrate for the polyoxyalkylene alkyl ether carboxylic acid or a salt thereof. The reaction is preferably carried out until the reaction rate exceeds 95%, more preferably more than 96%.

  In the method for producing a polyoxyalkylene alkyl ether carboxylic acid or a salt thereof according to this embodiment, it is preferable to stop the supply of the oxygen-containing gas into the slurry when the dissolved oxygen concentration in the slurry rises sharply.

  When oxygen is supplied into the liquid phase containing the polyoxyalkylene alkyl ether, oxygen is consumed by the oxygen oxidation reaction of the polyoxyalkylene alkyl ether. When the oxidation reaction is completed, the consumption of oxygen supplied to the liquid phase stops, so that the oxygen supplied to the liquid phase remains, and significant foaming occurs in the liquid phase due to oxygen that can no longer be dissolved in the liquid phase. It is difficult to extract the generated bubbles from the reactor, and the filtration accuracy and filtration speed are further reduced. Therefore, it is necessary to take measures such as leaving the foam until it disappears or adding an antifoaming agent to the liquid phase in advance, but standing still significantly reduces the production efficiency, and the antifoaming agent reacts. Affects foaming performance when using the product as a cleaning agent. Therefore, in producing a surfactant for use as a cleaning agent, it is generally not performed to blow a gas into a liquid phase such as an aqueous solution containing a product.

  It is preferable to maintain the dissolved oxygen concentration in the slurry in the range of 0 to 1.0 mg / L. However, even if the dissolved oxygen concentration is managed, when the oxidation reaction is completed, the dissolved oxygen concentration is removed from the management. A steep rise of In this case, from the viewpoint of avoiding foaming of the slurry, it is preferable to stop supplying the oxygen-containing gas in the slurry when the dissolved oxygen concentration in the slurry exceeds 3.0 mg / L. It is more preferable to stop when exceeding, and it is further preferable to stop when exceeding 1.0 mg / L.

[Filtering process]
In the method for producing a polyoxyalkylene alkyl ether carboxylic acid or a salt thereof according to the present embodiment, after the reaction step, the produced reaction solution containing the polyoxyalkylene alkyl ether carboxylic acid or a salt thereof is filtered with a sulfone polymer. Is used to separate and remove the precious metal-supported catalyst and the fine particles of the substance derived from the catalyst contained in the reaction solution.

<Filter media>
The filter medium is made of a sulfone polymer in the form of a membrane. Examples of the sulfone polymer forming the filter medium include polysulfone and polyethersulfone. Of these, polysulfone and polyethersulfone are preferred, and polysulfone is more preferred from the viewpoint of achieving both reliable removal of fine powder and filtration speed.

  The cause of the above effect is not clear, but it is considered that the sulfone polymer makes some interaction with the polyoxyalkylene alkyl ether carboxylic acid or a salt thereof to facilitate separation of the noble metal-supported catalyst.

The rated filtration accuracy of the filter medium is preferably 1 μm or less, more preferably 0.8 μm or less, and still more preferably 0.5 μm or less from the viewpoint of preventing filtration leakage. On the other hand, the rated filtration accuracy of the filter medium is preferably 0.05 μm or more, more preferably 0.1 μm or more, and more preferably 0.2 μm or more from the viewpoint of increasing the filtration speed and performing microfiltration in a short time. Is more preferable. The rated filtration accuracy of the filter medium is a particle diameter with a β value of 5000. Β value is β = (number of primary side particles) / (number of secondary side particles)
Is calculated by

  The filter medium has an asymmetric structure in which the pore size gradually decreases along the flow direction, that is, from the upstream side to the downstream side in the thickness direction, from the viewpoint of increasing the filtration speed and performing microfiltration in a short time. It is preferable. The filter medium having such a structure can be manufactured by a method of laminating filter media having different pore sizes in a multilayer manner, or a known method disclosed in, for example, JP-T-2001-509431.

<Filtration temperature>
The temperature of the reaction solution during microfiltration is preferably 20 ° C. or higher, more preferably 30 ° C. or higher, and still more preferably 40 ° C. or higher, from the viewpoint of lowering the viscosity and increasing the filtration speed. On the other hand, the temperature of the reaction solution during microfiltration is preferably 100 ° C. or less, and preferably 90 ° C. or less, from the viewpoint of preventing deterioration of the quality of the polyoxyalkylene alkyl ether carboxylic acid or its salt due to heat. More preferably, it is still more preferably 80 ° C. or less.

<Pressure>
The pressure during microfiltration is preferably 1.0 MPa or less, more preferably 0.5 MPa or less, and still more preferably 0.3 MPa or less, from the viewpoint of considering the pressure resistance of the apparatus and the filter medium. .

<Solid-liquid separation before microfiltration>
In the method for producing a polyoxyalkylene alkyl ether carboxylic acid or a salt thereof according to this embodiment, it is preferable to subject the reaction liquid, which is a slurry after the reaction, to solid-liquid separation before microfiltration. When the concentration of the noble metal catalyst in the reaction solution after the reaction is high, if it is subjected to microfiltration as it is, a catalyst cake layer is formed on the filter medium, and this catalyst cake layer becomes a resistance and the filtration speed decreases. In order to prevent this, the filtration area may be increased, but a large housing is required and a large number of filter media are required, resulting in an increase in cost. However, by performing the solid-liquid separation process before the microfiltration, coarse particles in the reaction liquid can be removed, and such inconvenience can be avoided.

  As the solid-liquid separation processing means, for example, a method of separating particles by generating a relative velocity between the particles and the liquid phase by gravity, centrifugal force, buoyancy, inertia force, etc., or collecting particles by obstacles or collectors. And a method of separating the liquid by passing it through. Specific examples of the former method include sedimentation separation, centrifugation, and flotation separation. Specific examples of the latter method include filtration and pressing. Of these, filtration is preferable from the viewpoint of good operability and excellent energy saving.

  The filtration as the solid-liquid separation treatment is preferably cake filtration in which the reaction solution is filtered with a filter medium, and the filter cake layer formed on the filter medium surface soon after the start of filtration acts as the filter medium in the subsequent filtration.

  In cake filtration, the permeability of the filtrate increases as the thickness of the cake layer increases. Therefore, the filtrate immediately after the start of cake filtration has a low permeability, and if it is microfiltered, the load on the filter medium increases. Therefore, the filtrate with low permeability immediately after the start of cake filtration (reaction solution after cake filtration) is returned to the reaction solution before cake filtration, whereby cake filtration is repeated, and the permeability of the reaction solution after cake filtration is somewhat high. After that, it is preferable to shift to microfiltration. From the viewpoint of increasing the filtration speed in microfiltration for a short time and the cost of reducing the cost by extending the life of the filter media, the transition of the reaction liquid after the cake filtration has reached 50% or more. The time is preferably set, more preferably 80% or more, and even more preferably 90% or more. The transmittance is measured as a relative value with respect to a standard sample having a transmittance of 100% using an ultraviolet-visible spectrophotometer (for example, model number: UVmini-1240 manufactured by Shimadzu Corporation).

  The standard sample is preferably one in which the precious metal-supported catalyst contained in the reaction solution and the fine powder of the substance derived therefrom are completely removed from the reaction solution.

  The temperature of the reaction solution during cake filtration is preferably 20 ° C. or higher, more preferably 30 ° C. or higher, and still more preferably 40 ° C. or higher, from the viewpoint of decreasing the viscosity and increasing the filtration speed. On the other hand, the temperature of the reaction solution at the time of cake filtration is preferably 100 ° C. or less, and preferably 90 ° C. or less, from the viewpoint of preventing deterioration of the quality of the polyoxyalkylene alkyl ether carboxylic acid or its salt due to heat. More preferably, it is still more preferable to set it as 80 degrees C or less.

  The pressure during cake filtration is preferably 1.0 MPa or less, more preferably 0.5 MPa or less, and still more preferably 0.3 MPa or less, from the viewpoint of considering the pressure resistance of the apparatus and the filter medium. .

  Examples of the cake filtration operation method include constant-rate filtration in which the filtrate flow rate is made constant using a constant-capacity pump, low-pressure filtration that keeps the pressure on the primary side of the filter medium constant, and pumps other than the constant-capacity pump For example, a variable speed filtration that performs filtration while changing both the filtration pressure and the filtration speed while keeping the pump output constant.

  The filter medium used in the cake filtration is not particularly limited as long as a cake layer is formed after the filtration starts and a filtrate having a desired permeability can be obtained. For example, woven cloth, non-woven filter medium, polymer membrane, porous filter medium Etc. In order to increase the filtration speed, it is advantageous that the filtration area is wide, and from the viewpoint of economy that it is inexpensive, a woven fabric is preferred.

  The solid-liquid separation treatment and microfiltration may be performed in a continuous operation, or the reaction liquid subjected to the solid-liquid separation treatment may be temporarily collected in an intermediate tank and separately subjected to microfiltration. From the viewpoint that an intermediate tank is unnecessary and the operation time can be shortened, continuous operation is preferable among these.

  In the solid-liquid separation treatment, solid-liquid separation is performed until the permeation rate of the reaction liquid reaches 50% or more from the viewpoint of increasing the filtration speed in microfiltration for a short time and from the viewpoint of extending the life of the filter medium to reduce costs. It is preferable to perform solid-liquid separation until 80% or more, and even more preferably solid-liquid separation until 90% or more.

[Production process]
In this embodiment, when manufacturing polyoxyalkylene alkyl ether carboxylic acid under acidic conditions, the carboxylic acid contained in the reaction liquid after a filtration process can be made into a product as it is.

  Moreover, when manufacturing polyoxyalkylene alkyl ether carboxylate under alkaline conditions, in the reaction liquid after a filtration process, some or all of polyoxyethylene alkyl ether carboxylic acid is melt | dissolving in the form of a salt. Therefore, after adjusting the pH, the product can be directly used as a surfactant solution. Furthermore, it can be converted into an acid form with a mineral acid such as hydrochloric acid, and a carboxylic acid liberated through an extraction step can be used as a product.

(Preparation of reaction solution)
In a stirred tank reactor, a polyoxyalkylene alkyl ether (hereinafter referred to as “AE”) in which R: lauryl group, AO: ethyleneoxy group, and n: 3 in the above general formula (I), and the above general formula (II) are used. ) And m: 1 and M: Na polyoxyalkylene alkyl ether carboxylate (hereinafter referred to as “EC”), sodium hydroxide, activated carbon (Peat charcoal) as platinum 1 mass%, palladium 4 mass% , And a noble metal-supported catalyst supporting 5% by mass of bismuth and water were charged, and 2409 kg of a slurry was prepared by stirring them. The content of each component in the slurry was 12% by mass for AE, 8.5% by mass for EC, 1.4% by mass for sodium hydroxide, 0.98% by mass for the noble metal supported catalyst, and the balance being water. It was. When the particle size of the noble metal-supported catalyst was measured using a laser diffraction / scattering type particle size distribution measuring apparatus (Horiba, Ltd., device model number: LA-920), the 10% diameter was 10 μm, and the 50% diameter (median diameter) was 32 μm. And the 90% diameter was 87 μm.

  By blowing oxygen into the slurry, AE was oxidized with oxygen to produce EC. The reaction temperature was 70 ° C. and the reaction pressure was 0.1 MPa. The reaction time was 8 hours, and no outflow of the reaction solution due to foaming occurred. The reaction rate of the EC aqueous solution slurry after the reaction was calculated based on the Epton method and found to be 98%.

  EC aqueous solution slurry was charged into a bag filter (Eaton Filtration Co., Ltd. housing: GAF filter (model: RTB-1BSLJ), filter medium: LOFCLEAR (model number LCR-123)) and cake filtered at a temperature of 70 ° C. and a pressure of 0.15 MPa ( (Solid-liquid separation process) was performed, and the filtrate was recovered as a reaction liquid for performing microfiltration.

  The above operation was performed in two batches to prepare a first batch of reaction solution 1 and a second batch of reaction solution 2.

(Microfiltration of reaction liquid)
The following examples were carried out using an experimental apparatus in which a nitrogen supply pipe was connected to the upper part of a 1 L container provided with a ribbon heater and a lab disk holder (model number: LDH-L1 filtration area 0.00038 m ² manufactured by Loki Techno Co.) was connected to the lower part. 1 to 3 and Comparative Examples 1 to 5 were subjected to microfiltration tests.

<Example 1>
The reaction solution 1 was put into a 1 L container, and a filter medium (Water Fine WFN 0.1, rated filtration accuracy 0.1 μm, manufactured by Nippon Pole Co., Ltd.) was set in a lab disk holder.

  The temperature of the reaction liquid 1 in the 1 L container is maintained at 70 ° C., nitrogen gas is supplied from the nitrogen supply pipe to the 1 L container, and the reaction liquid 1 is maintained at a pressure of 0.02 MPa. Microfiltration was performed through a holder.

  The mass of the collected filtrate was 20 g, and the filtration time was 599 seconds.

<Example 2>
Microfiltration was performed in the same manner as in Example 1 except that a filter medium made of a sulfone polymer (Water Fine WFN 0.2, rated filtration accuracy 0.2 μm manufactured by Nippon Pole Co., Ltd.) was used.

  The mass of the collected filtrate was 20 g, and the filtration time was 282 seconds.

<Example 3>
Microfiltration was performed in the same manner as in Example 1 except that the filter medium (Water Fine WFN 0.8, rated filtration accuracy 0.8 μm, manufactured by Nippon Pole Co., Ltd.) formed of the reaction solution 2 and the sulfone polymer was used. .

  The mass of the collected filtrate was 300 g and the filtration time was 1178 seconds.

<Comparative Example 1>
Microfiltration was performed in the same manner as in Example 1 except that a filter medium (CTX-001 manufactured by Loki Techno Co., filtration accuracy: 0.1 μm) formed of polytetrafluoroethylene was used.

  The mass of the collected filtrate was 3 g and the filtration time was 1241 seconds.

<Comparative example 2>
Microfiltration was performed in the same manner as in Example 1 except that a filter medium (CTX-002, manufactured by Loki Techno Co., filtration accuracy: 0.2 μm) formed of polytetrafluoroethylene was used.

  The mass of the collected filtrate was 15 g and the filtration time was 1251 seconds.

<Comparative Example 3>
Microfiltration was performed in the same manner as in Example 1, except that a filter medium (IMC020 manufactured by Cuno, filtration accuracy: 0.2 μm) formed of nylon was used.

  The mass of the collected filtrate was 25 g and the filtration time was 1200 seconds.

<Comparative example 4>
Microfiltration was performed in the same manner as in Example 1 except that a filter medium made of polypropylene (Polyfine II PFT 0.25, rated filtration accuracy 0.25 μm manufactured by Nippon Pole Co., Ltd.) was used.

  The mass of the collected filtrate was 20 g and the filtration time was 304 seconds.

<Comparative Example 5>
The same microfiltration as in Example 1 was performed except that a filter medium made of polypropylene (Polyfine II PFT 0.45, rated filtration accuracy 0.45 μm, manufactured by Nippon Pole Co., Ltd.) was used.

  The mass of the collected filtrate was 20 g and the filtration time was 152 seconds.

(Test evaluation method)
<Filter speed>
About each of Examples 1-3 and Comparative Examples 1-5, the mass of the collect | recovered filtrate was remove | divided by the filtration area and the filtration time, and it was set as the filtration speed (kg / m < ² > * h).

<Transparency>
About each of Examples 1-3 and Comparative Examples 1-5, the transmittance | permeability of the collect | recovered filtrate was 100% of the transmittance | permeability of a standard sample using the ultraviolet visible spectrophotometer (Shimadzu Corporation model number: UVmini-1240). As measured relative to it. A measurement cell made of polystyrene having an optical path length of 10 mm was used, and the wavelength of the measurement light was 550 nm. As the standard sample, a filtrate obtained by microfiltration of the filtrate to be measured with a PTFE membrane filter (Product name: DISMIC 25JP020AN, pore size 0.2 μm, manufactured by Advantech Toyo Co., Ltd.) was used.

  In addition, when the transmittance | permeability was measured by the same method about the reaction liquids 1 and 2 before microfiltration, the reaction liquid 1 was 96.5% and the reaction liquid 2 was 96.8%.

(Test evaluation results)
Table 1 shows the test results.

Filtration rate is Example 1 316 kg ^{/ m} 2 h, Example 2 672kg ^{/ m} 2 h, Example 3 2413kg ^{/ m} 2 h, Comparative Example 1 23 kg ^{/ m} 2 h, the Comparative Example 2 114 kg / m ² h, Comparative Example 3 was 197 kg / m ² h, Comparative Example 4 was 623 kg / m ² h, and Comparative Example 5 was 1247 kg / m ² h.

  The transmittance was 99.3% in Example 1, 99.6% in Example 2, 99.8% in Example 3, 100% in Comparative Example 1, 100% in Comparative Example 2, and 99 in Comparative Example 3. 0.7%, Comparative Example 4 was 98.3%, and Comparative Example 5 was 98.0%.

  From the results of Example 1 and Comparative Example 1 and Example 2 and Comparative Example 2, it is found that the filtration speed is remarkably high when the filter medium is polysulfone when compared using the same rated filtration accuracy. It was.

  From the results of Examples 2 and 3 and Comparative Example 3, it was found that when the filter medium is polysulfone, it is excellent in fine powder removability even when the filter speed is equal or higher.

  The present invention is useful for a method for producing a polyoxyalkylene alkyl ether carboxylic acid and a salt thereof.

Claims (5)

  Polyoxyalkylene alkyl ether, precious metal-supported catalyst using activated carbon as support, and oxygen-containing gas in contact with slurry containing water to oxidize polyoxyalkylene alkyl ether to polyoxyalkylene alkyl ether carboxylate And then filtering the reaction solution containing the produced polyoxyalkylene alkyl ether carboxylate salt with a filter medium comprising a sulfone polymer, thereby separating the noble metal-supported catalyst contained in the reaction solution. And a process for producing a polyoxyalkylene alkyl ether carboxylate. The method for producing a carboxylate according to claim 1, wherein the polyoxyalkylene alkyl ether carboxylate is represented by the following formula.
{RO- (AO) _n-1 -A'-COO} _m M
[Wherein, R represents a hydrocarbon group having 4 to 30 carbon atoms, AO represents an alkyleneoxy group having 2 to 4 carbon atoms, n represents an average added mole number of AO of 1 to 100, and A ′ represents 1 to 1 carbon atoms. 3 alkylene groups, M is a cation, and m is the valence of M. ]   The method for producing a carboxylate according to claim 1 or 2, wherein a solid-liquid separation treatment of the reaction solution is performed before filtration.   The said filter medium is a manufacturing method of the carboxylate of Claims 1 thru | or 3 which has a structure where the magnitude | size of a hole reduces along the direction of the flow of a reaction liquid.   A polyoxyalkylene alkyl ether is oxidized by contacting a gas containing oxygen with a slurry containing water and a noble metal-supported catalyst having activated carbon as a carrier, and a water-containing slurry. And a step of separating the noble metal-supported catalyst contained in the reaction solution by filtering the reaction solution containing the generated polyoxyalkylene alkyl ether carboxylic acid using a filter medium made of a sulfone polymer. A process for producing a polyoxyalkylene alkyl ether carboxylic acid.