JP6264947B2 - Process for producing a mixture of diphenylmethanediamine and polyphenylenepolymethylenepolyamine - Google Patents

Description

  The present invention relates to a method for producing a mixture of bicyclic diphenylmethanediamine and highly condensed polyphenylenepolymethylenepolyamine by reacting aniline with formaldehyde using hydrochloric acid as a catalyst. In addition, the mixture of diphenylmethanediamine and polyphenylene polymethylene polyamine may be collectively referred to as “MDA” hereinafter.

  MDA is an important organic compound that is used as a curing agent for epoxy resins and polyurethane resins, or is used as a raw material for polyurethane resins by reacting with phosgene to form isocyanates.

  This MDA is generally produced by a condensation reaction of aniline and formaldehyde using an acid as a catalyst, followed by a rearrangement reaction. In particular, hydrochloric acid is widely used as the acid (see, for example, Patent Document 1).

  Hydrochloric acid after the rearrangement reaction is neutralized with sodium hydroxide, sodium chloride is by-produced into an aqueous solution (hereinafter referred to as salt water), and separated into an organic phase mainly composed of MDA.

  Since this organic phase contains impurities such as aniline derived from the raw material in addition to MDA, it is commercialized as purified MDA after removing these by distillation or the like.

  On the other hand, since organic substances such as MDA and aniline are contained in salt water at high concentrations, organic substances are separated from the need to reduce the COD (Chemical Oxygen Requirement Substance) load on the environment when discharging into public waters. Or a removal method is taken. However, the conventional method is not always sufficient as a method for separating and removing organic substances effectively and efficiently.

  For example, a method of extracting and removing organic substances contained in salt water with toluene has been proposed (see, for example, Patent Document 2). Certainly, a part of the organic matter can be removed by this method, but most of it remains in the salt water, so that there is a problem that the COD load on the environment cannot be sufficiently reduced.

  Further, a method has been proposed in which salt water is extracted with an organic solvent, organic substances having a relatively low boiling point are removed by distillation, and the remaining organic substances are subsequently adsorbed and removed with an adsorbent such as activated carbon (for example, Patent Document 3). reference). Certainly, many organic substances in salt water can be removed by this method, but extraction, distillation, and adsorption by activated carbon or the like are greatly affected by the pH of the salt water.

  For this reason, a method of reusing treated salt water as a salt electrolysis raw material by carrying out purification such as extraction or distillation at a pH of less than 8 has been proposed (Patent Document 4). Certainly, salt water can be purified to some extent by this method, but depending on the type of organic matter, it cannot be sufficiently removed at a pH of less than 8, and when the salt water is recycled as a raw material for salt electrolysis, the organic matter becomes an ion exchange membrane. The film deposited and deposited on the surface and inside of the film increased the resistance of the film, increasing the electrolysis voltage, and shortening the life of the ion exchange film. Furthermore, depending on the type and concentration of the organic matter remaining in the salt water, it may be mixed as impurities in the caustic soda and chlorine gas as products, leading to a reduction in quality.

Japanese Patent Laid-Open No. 4-154744 JP 2004-26753 A Special table 2011-523648 gazette JP 2009-209144 A

  The present invention has been made in view of the above-mentioned background art, and its purpose is to effectively purify organic matter in salt water and use it as a raw material for ion-exchange membrane method salt electrolysis, which is effective and efficient MDA. It is in providing the manufacturing method of.

  As a result of intensive investigations on a method for highly purifying salt water produced as a by-product when producing MDA, the present inventors have refined salt water under a specific treatment method and specific treatment conditions, and thereby, It has been found that organic substances can be removed to such a low concentration that it can be used as a raw material for salt exchange electrolysis by ion exchange membrane method, and the present invention has been completed.

  That is, this invention is a manufacturing method of the mixture of diphenylmethane diamine and polyphenylene polymethylene polyamine as shown below.

[1] Step 1 of reacting aniline and formaldehyde in the presence of hydrochloric acid as a catalyst,
Step 2, in which sodium hydroxide is added to the reaction solution containing the mixture of diphenylmethanediamine and polyphenylene polymethylene polyamine obtained in Step 1 to bring the pH to a range of 10-14,
Step 3, in which the reaction solution obtained in Step 2 is phase-separated into an organic phase containing a mixture of diphenylmethanediamine and polyphenylenepolymethylenepolyamine and an aqueous phase mainly composed of sodium chloride.
Step 4, in which an organic solvent is added to the aqueous phase obtained in Step 3 and the organic matter in the aqueous phase is extracted within a pH range of 10 to 14 and phase-separated into an aqueous phase and an organic phase,
Step 5 of stripping the aqueous phase obtained in Step 4 in the range of pH 10 to 14 to remove organic substances in the aqueous phase,
The aqueous phase obtained in step 5 is subjected to adsorption treatment with activated carbon in the range of pH 10 to 14, and the organic phase in the aqueous phase is separated, and the aqueous phase obtained in step 6 is adjusted to pH 8 to 10 In the range of the step 7, adsorption treatment with activated carbon to remove organic matter in the aqueous phase,
Of a mixture of diphenylmethanediamine and polyphenylenepolymethylenepolyamine containing

  [2] The production method according to [1] above, wherein the activated carbon adsorption treatment of Step 6 and Step 7 is performed on a fixed bed.

  [3] The production method according to the above [1] or [2], wherein the activated carbon used in Step 6 or Step 7 is regenerated by passing a regenerating solution and reused.

  [4] The method according to any one of [1] to [3], wherein the pH of the aqueous phase in step 7 is in the range of 9 to 10.

  [5] The method according to any one of [1] to [4], wherein the TOC (total organic carbon) concentration in the aqueous phase obtained in step 7 is 8 ppm by weight or less. .

  [6] The production method according to any one of the above [1] to [5], wherein the aqueous phase obtained in step 7 is used as a raw material for salt electrolysis by ion exchange membrane method.

  According to the method of the present invention, salt water produced as a by-product during MDA production can be highly purified, and not only reducing the environmental load, but also using it as an ion exchange membrane salt electrolysis raw material for effective use of resources. Connected.

  Hereinafter, the present invention will be described in detail.

  In the present invention, Step 1 is a step of reacting aniline and formaldehyde in the presence of hydrochloric acid as a catalyst, and a widely known method can be used. Specifically, the molar ratio of aniline to formaldehyde is preferably 1 to 5, and the molar ratio of hydrochloric acid to aniline is preferably 0.05 to 1. MDA can be synthesized by a condensation reaction between aniline and formaldehyde, followed by a rearrangement reaction. The condensation reaction temperature is preferably 70 ° C. or lower, and the rearrangement reaction temperature is preferably 90 ° C. or higher. The reaction mode can be preferably carried out continuously or batchwise.

  In the present invention, Step 2 is a step in which sodium hydroxide is added to the reaction solution containing MDA obtained in Step 1 so that the pH is in the range of 10-14. Here, if the pH is less than 10, the phase separation between the aqueous phase and the organic phase is lowered, and if it is more than 14, sodium hydroxide is required in a large excess, which is not preferable because the drug cost increases.

  In the present invention, Step 3 is a step of separating the reaction solution obtained in Step 2 into an organic phase containing MDA and an aqueous phase (brine) containing sodium chloride as a main component. Since the organic phase contains impurities such as aniline derived from the raw material in addition to MDA, purified MDA can be obtained by removing these by distillation or the like.

  On the other hand, in addition to sodium chloride, organic substances such as MDA, aniline, formaldehyde, methanol, and phenol are mixed in the aqueous phase.

  In the present invention, in step 4, an organic solvent is added to the aqueous phase obtained in step 3, and organic substances in the aqueous phase are extracted in the range of pH 10 to 14, and the phases are separated into an aqueous phase and an organic phase. It is a process.

  The pH of the aqueous phase in the extraction treatment is essentially 10-14. By setting this pH range, organic substances can be extracted more efficiently. The organic solvent added to the aqueous phase obtained in step 3 is not particularly limited as long as it does not react with MDA or aniline dissolved in salt water and can dissolve MDA or aniline. An aromatic organic solvent is preferable in view of the solubility of MDA and aniline, and specific examples include toluene, benzene, aniline and the like. Among these, aniline can be preferably used because it is also a synthetic raw material for MDA.

  The extraction temperature is not particularly limited, and it may be heated or cooled with steam, a heat exchanger or the like as it is during the reaction. However, if the temperature is too low, the phase separation after extraction becomes poor, and if it is too high, a high-grade material is required to suppress corrosion of the apparatus. Preferably it is 10-100 degreeC, More preferably, it is the range of 20-95 degreeC.

  About the density | concentration of the salt water to extract, the density | concentration discharged | emitted at the time of normal MDA manufacture may be sufficient, and it does not specifically limit. Specifically, it is preferably 10 to 25% by weight, more preferably 12 to 24% by weight.

  In the present invention, step 5 is a step of stripping the aqueous phase obtained in step 4 in the range of pH 10 to 14 to remove organic substances in the aqueous phase.

  Here, among organic substances dissolved in the aqueous phase, those having a low boiling point and organic substances having a low solubility in water are removed by stripping. By setting the pH of the aqueous phase to 10 to 14, the efficiency of stripping is enhanced. For stripping, steam or an inert gas (for example, nitrogen gas) can be used. From the viewpoint of cost, water vapor is preferable. The processing format here may be a continuous type or a batch type.

  In the present invention, Step 6 is a step of subjecting the aqueous phase obtained in Step 5 to adsorption treatment with activated carbon in the range of pH 10 to 14, and separating organic substances in the aqueous phase.

  In step 6, in order to adsorb the organic matter in the aqueous phase obtained in step 5, the aqueous phase is treated with activated carbon in the range of pH 10-14. Examples of the shape of the activated carbon that can be used here include a granular shape, a crushed shape, a spherical shape, and a powder shape, and are not particularly limited. Of these, considering the ease of handling and the amount of organic matter adsorbed, granular and crushed activated carbon is preferred.

  The type of the reactor in which the aqueous phase and activated carbon are brought into contact with each other can be appropriately selected depending on the amount of treatment of the aqueous phase, the shape and usage of the activated carbon, and is not particularly limited. From the standpoints of adsorbability of organic matter and equipment cost, a fixed bed filled with granular or crushed activated carbon, or a stirring tank in which powdered activated carbon is suspended can be suitably used. More preferred is a fixed bed filled with granular or crushed activated carbon. In addition, when processing by suspending powdery activated carbon, it is necessary to isolate | separate activated carbon from an aqueous phase after that.

  Examples of the activated carbon include, but are not limited to, coconut shell, coal, activated carbon obtained by regenerating activated carbon once used, and the like. Among these, in view of the adsorptivity of organic matter and price, coconut shell system and activated charcoal are preferable, and coconut shell system is more preferable.

  The adsorption treatment temperature of the aqueous phase with activated carbon is not particularly limited. Even if the water phase temperature remains at the time of stripping, it may be heated or cooled with steam, a heat exchanger or the like. Increasing the treatment temperature can increase the adsorption rate of organic matter to activated carbon, but the amount of adsorption is slightly reduced, and if the temperature is too low, the adsorption rate of organic matter is reduced. A preferred temperature is in the range of 10 to 90 ° C, more preferably 15 to 80 ° C.

  In the present invention, Step 7 is a step of removing the organic matter in the aqueous phase by subjecting the aqueous phase obtained in Step 6 to adsorption treatment with activated carbon in the range of pH 8-10.

  Here, organic substances such as phenol contained in the aqueous phase are removed by adsorption. The pH can be adjusted by adding a mineral acid to the aqueous phase. If the pH is less than 8, the amount of mineral acid used increases, so the cost increases. If it is greater than 10, the amount of organic matter adsorbed decreases. Preferably it is the range of pH 9-10.

  The mineral acid added to the aqueous phase is not particularly limited. For example, from the viewpoint of drug cost, hydrochloric acid, sulfuric acid, and nitric acid are preferable, and hydrochloric acid is more preferable.

  Regarding the shape and type of the activated carbon, the type and temperature of the reactor, the treatment conditions with activated carbon in Step 6 described above can be applied.

  When the activated carbon used in Step 6 or Step 7 reaches the saturated adsorption amount, it becomes impossible to adsorb organic matter any more. Therefore, it is preferable to replace the activated carbon before or after reaching the saturated adsorption amount. Here, a preferable method is to perform a regeneration treatment such as desorption of organic substances from the activated carbon to be exchanged. As the regeneration solution used for the regeneration treatment, for example, an alcohol solution such as ethanol or methanol or an aqueous alkali hydroxide solution can be applied. A preferred regenerating solution is an aqueous sodium hydroxide solution having a low drug cost. For example, the concentration in the case of using sodium hydroxide as the regenerating solution is not particularly limited, but if it is too low, it takes time for regeneration, and if it is too high, the cost increases. % By weight, more preferably 0.2 to 10% by weight, still more preferably 0.5 to 5% by weight.

  In addition, when using activated carbon in a fixed bed, the regeneration solution may be passed through any of the continuous, semi-continuous, or batch systems, but it must be continuous or semi-continuous. Is preferable because the time for the regeneration treatment can be shortened and the amount of the regeneration solution used can be reduced.

  The TOC (total organic carbon) concentration in the water phase purified by the above steps can be reduced to 10 ppm by weight or less, and can be used as a raw material for ion exchange membrane salt electrolysis. It is preferably 8 ppm by weight or less, more preferably 7 ppm by weight or less, as a raw material for ion exchange membrane method salt electrolysis.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is limited to these Examples and is not interpreted.

  In addition, the quantitative analysis of the TOC concentration in the present invention was performed by an absolute calibration curve method using a TOC analyzer (manufactured by Shimadzu Corporation, TOC-V).

Example 1.
A 500 L jacketed reaction vessel was charged with 125.0 kg of aniline, 50.6 kg of 37% by weight formalin and 130.0 kg of 35% by weight hydrochloric acid, and reacted at a stirring speed of 40 rpm and a temperature of 50 ° C. for 2 hours. Thereafter, the stirring speed was increased to 120 rpm, steam was fed to the jacket of the reaction vessel, the reaction temperature was raised to 90 ° C., and the reaction was carried out for 3 hours. After completion of the reaction, the pH was adjusted to 13.5 with a 40 wt% aqueous sodium hydroxide solution, and then the mixture was settled and separated into two layers. The upper organic phase is mainly composed of MDA, from which impurities are removed to obtain purified MDA as a product.

  The lower aqueous phase was salt water, and 286.3 kg could be recovered. Of this brine, 250.3 kg was extracted with toluene at pH 13.5. Subsequently, the treated salt water was stripped with steam to remove the dissolved organic substances such as toluene and purified. The amount of salt water obtained was 245.8 kg, the NaCl concentration was 25.3% by weight, and the TOC concentration was 10.3 ppm by weight.

  After cooling the treated salt water to 90 ° C., the salt water was continuously passed through a fixed bed column having an inner diameter of 5 cm and a packing height of 1 m filled with activated carbon at pH 13.5 at a flow rate of 10.2 kg / hr for 10 hours. It processed and adsorb | sucked organic substances, such as aniline.

  Hydrochloric acid was added to the treated salt water obtained here to adjust the pH to 9.0, a temperature of 60 ° C., and a fixed bed column packed with activated carbon separately prepared and having an inner diameter of 5 cm and a packing height of 1 m to a flow rate of 10.2 kg / hr. For 10 hours. The TOC concentration of the obtained brine was 4.1 ppm by weight.

This treated salt water was continuously supplied at a flow rate of 602 g / hr to the anode chamber of an ion exchange membrane salt solution electrolytic cell having a membrane area of 30 cm ² and electrolyzed. As a result of continuous operation for 100 hours at 6 kA / m ² , the initial cell voltage was 3.01 V, the current efficiency was 96.8%, the cell voltage after 100 hours was 3.02 V, and the current efficiency was 96.9%. No change over time was observed, and it was found that the treated salt water can be used as a raw material for salt electrolysis with ion exchange membrane method.

Comparative Example 1
The temperature of the salt water obtained by steam stripping in Example 1 was cooled to 80 ° C., hydrochloric acid was added to pH 4.1, and then the salt water was applied to the fixed bed column packed with activated carbon used in Example 1. The solution was continuously passed for 10 hours at a flow rate of 10.1 kg / hr.

  Furthermore, hydrochloric acid was added to the treated salt water obtained here to adjust the pH to 3.3, the temperature was 60 ° C., and the salt water was fed to the fixed bed column packed with the activated carbon used in Example 1 at a flow rate of 10.1 kg / hr. The solution was continuously passed through for 10 hours. The TOC concentration of the obtained brine was 9.7 ppm by weight, and aniline remained 4.9 ppm by weight in terms of TOC.

  Electrolysis was started by continuously supplying this treated salt water at a flow rate of 600 g / hr as a raw material for the ion exchange membrane method salt electrolytic cell used in Example 1, but the explosion occurred in the chlorine gas generated from the anode of the electrolytic cell. The electrolysis experiment was immediately stopped because it was found that nitrogen trichloride was present.

Comparative Example 2.
After the temperature of the salt water obtained by steam stripping in Example 1 was cooled to 90 ° C., a flow rate of 10.1 kg / hr of salt water was applied to a fixed bed column packed with activated carbon used in Example 1 at pH 13.5. For 10 hours continuously.

  Further, the solution was continuously passed for 10 hours at a flow rate of 10.2 kg / hr through a fixed bed column having an inner diameter of 5 cm and a packing height of 1 m filled with activated carbon prepared separately at a temperature of 60 ° C. while maintaining pH 13.5. The TOC concentration of the obtained salt water was 10.2 ppm by weight.

  Electrolysis was started by continuously supplying this treated salt water at a flow rate of 603 g / hr as a raw material for the ion exchange membrane salt electrolyzer used in Example 1, but the yellow oil content was added to the treated salt water after electrolysis. Since formation was observed, the electrolysis experiment was stopped.

Example 2
The reaction vessel with a jacket of 500 L used in Example 1 was charged with 192.3 kg of aniline, 78.5 kg of 37% by weight formalin, and 40.5 kg of 35% by weight hydrochloric acid, and the stirring speed was 40 rpm and the temperature was 40 ° C. For 3 hours. Thereafter, the stirring speed was increased to 120 rpm, steam was fed to the jacket of the reaction vessel, and the reaction temperature was raised to 95 ° C. for 4 hours. After completion of the reaction, the pH was adjusted to 13.2 with solid sodium hydroxide, and then settled to separate two layers. The upper organic phase is mainly composed of MDA, from which impurities are removed to obtain purified MDA as a product.

  The lower aqueous phase was salt water, and 115.3 kg could be recovered. Of this brine, 100.6 kg was extracted with benzene at pH 13.5. Subsequently, the treated brine was stripped with steam to remove the dissolved organic matter such as benzene and purified. The amount of salt water obtained was 98.7 kg, the NaCl concentration was 18.8 wt%, and the TOC concentration was 22.5 wt ppm.

  After cooling the temperature of the treated salt water to 90 ° C., the salt water was continuously passed through the fixed bed column filled with the activated carbon used in Example 1 at pH 13.2 at a flow rate of 9.5 kg / hr for 10 hours. It processed and adsorb | sucked organic substances, such as aniline.

  Hydrochloric acid was added to the treated salt water obtained here to adjust the pH to 9.2, and the fixed bed column used in Example 1 was continuously passed through the fixed bed column used in Example 1 at a flow rate of 9.3 kg / hr for 10 hours. The TOC concentration of the obtained brine was 6.2 ppm by weight.

This treated salt water was continuously supplied to the anode chamber of an ion exchange membrane method salt electrolytic cell having a membrane area of 30 cm ² at a flow rate of 601 g / hr for electrolysis. As a result of continuous operation for 100 hours at a current density of 6 kA / m2, the initial cell voltage was 3.04 V, the current efficiency was 97.5%, the cell voltage after 100 hours was 3.04 V, and the current efficiency was 97.4%. Thus, it was found that the treated salt water can be used as a raw material for salt electrolysis of ion-exchange membrane method.

Example 3 FIG.
The reaction vessel with a jacket of 500 L used in Example 1 was charged with 160.1 kg of aniline, 65.4 kg of 37% by weight formalin and 67.5 kg of 35% by weight hydrochloric acid, with a stirring speed of 50 rpm and a temperature of 50 ° C. For 2 hours. Thereafter, the stirring speed was increased to 150 rpm, steam was fed to the jacket of the reaction vessel, the reaction temperature was increased to 93 ° C., and the reaction was carried out for 4 hours. After completion of the reaction, the pH was adjusted to 13.8 with 48% by weight sodium hydroxide, and then the mixture was settled and separated into two layers. The upper organic phase is mainly composed of MDA, from which impurities are removed to obtain purified MDA as a product.

  The lower aqueous phase was salt water and 177.6 kg could be recovered. Of this brine, 120.7 kg was extracted with aniline at pH 13.8. Subsequently, the treated brine was stripped with steam to remove the dissolved aniline and other organic substances and purified. The amount of salt water obtained was 117.7 kg, the NaCl concentration was 21.2 wt%, and the TOC concentration was 12.4 wt ppm.

  After cooling the temperature of the treated salt water to 80 ° C., the salt water is continuously passed through the fixed bed column filled with the activated carbon used in Example 1 at pH 13.2 at a flow rate of 11.3 kg / hr for 10 hours. Then, an organic substance such as aniline was adsorbed.

  Hydrochloric acid was added to the treated brine obtained here to adjust the pH to 9.1, and the solution was continuously passed through the fixed bed column used in Example 1 at a temperature of 60 ° C. at a flow rate of 11.1 kg / hr for 10 hours. The TOC concentration of the obtained brine was 5.3 ppm by weight.

This treated salt water was continuously supplied at a flow rate of 599 g / hr to the anode chamber of an ion exchange membrane salt solution electrolytic cell having a membrane area of 30 cm ² and electrolyzed. As a result of continuous operation for 100 hours at 6 kA / m ² , the initial cell voltage was 3.02 V, the current efficiency was 97.3%, the cell voltage after 100 hours was 3.01 V, and the current efficiency was 97.2%. No change over time was observed, and it was found that the treated salt water could be used as a raw material for salt exchange electrolysis by ion exchange membrane method.

  The present invention is a method for producing a mixture of diphenylmethanediamine and polyphenylenepolymethylenepolyamine by reacting aniline and formaldehyde in the presence of a hydrochloric acid catalyst, and neutralizing the hydrochloric acid catalyst after the reaction with sodium hydroxide Thus, the aqueous sodium chloride solution (salt water) obtained can be highly purified to reduce the burden on the environment when discarded, and further to a level that can be reused as a raw material for salt electrolysis.

Claims (6)

Sodium hydroxide is added to the reaction solution containing the mixture of diphenylmethanediamine and polyphenylenepolymethylenepolyamine obtained in Step 1 and Step 1 in which aniline and formaldehyde are reacted in the presence of hydrochloric acid as a catalyst, and the pH is adjusted to 10 to 10. Step 2 in which the reaction liquid obtained in Step 2 and Step 2 in the range of 14 is phase-separated into an organic phase containing a mixture of diphenylmethanediamine and polyphenylenepolymethylenepolyamine and an aqueous phase mainly composed of sodium chloride, An organic solvent is added to the aqueous phase obtained in step 3, the organic matter in the aqueous phase is extracted in the pH range of 10 to 14, and phase separation is performed into the aqueous phase and the organic phase. The aqueous phase obtained in Step 5 and Step 5 in which the obtained aqueous phase is stripped in the range of pH 10 to 14 and organic substances in the aqueous phase are removed is adjusted to pH Within a range of 0-14, and adsorption treatment with activated carbon, from a range of step 6 of separating the organic matter of the aqueous phase, and the aqueous phase obtained in step 6 with the addition of mineral acid pH 8-10, A method for producing a mixture of diphenylmethanediamine and polyphenylenepolymethylenepolyamine, comprising a step 7 of performing adsorption treatment with activated carbon and removing organic substances in the aqueous phase. The method according to claim 1, wherein the activated carbon adsorption treatment in steps 6 and 7 is performed on a fixed bed. The production method according to claim 1 or 2, wherein the activated carbon used in step 6 or step 7 is regenerated and reused by passing a regenerated solution. The production method according to any one of claims 1 to 3, wherein the pH of the aqueous phase in step 7 is in the range of 9 to 10. The manufacturing method according to any one of claims 1 to 4, wherein the TOC (total organic carbon) concentration in the aqueous phase obtained in step 7 is 8 ppm by weight or less. The production method according to any one of claims 1 to 5, wherein the aqueous phase obtained in step 7 is used as a raw material for ion exchange membrane salt electrolysis.