JP2013023464A - Method for producing succinic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a high-purity succinic acid which inhibits a by-product of a malic acid.SOLUTION: In the method for producing the succinic acid, hydrogenation reaction is performed by incorporating an aqueous solvent and a noble metal catalyst into a pressurizing reactor, thereafter, supplying a hydrogen gas until it become a pressurized state, and then adding a maleic anhydride or maleic acid of a raw material to the reactor, wherein 10 wt.% or more of the total amount of the maleic anhydride or maleic acid, which adds to the pressurizing reactor, is added by a consecutive addition system.

Description

  The present invention relates to a method for producing succinic acid, and more particularly to a method for producing high-purity succinic acid in which malic acid by-product is suppressed.

  Succinic acid is a useful compound obtained by hydrogenating maleic acid or maleic anhydride in an aqueous medium and used for food additives, pharmaceutical intermediates and the like. The succinic acid used for such applications requires high-purity succinic acid not only in terms of yield but also from the viewpoint of safety. By the way, in the method for producing succinic acid, malic acid in which water is added to maleic acid is by-produced. Therefore, in order to produce high-purity succinic acid, it is necessary to suppress the by-product of malic acid. The following chemical reaction formula shows the production route of maleic acid and malic acid, (A) is maleic anhydride, (B) is maleic acid, (C) is succinic acid, (D) is malic acid. is there.

  However, regarding the suppression of malic acid by-product, regarding the reaction temperature when maleic acid is brought into contact with a hydrogenation catalyst in the presence of hydrogen gas in an aqueous medium to produce succinic acid, if the temperature is too high, malic acid Therefore, it is proposed that 20 to 150 ° C. is usually selected (Patent Document 1).

Japanese Patent Laid-Open No. 9-31011

  In view of the above circumstances, an object of the present invention is to provide a method for producing high-purity succinic acid that suppresses by-product malic acid.

  That is, the gist of the present invention is that an aqueous solvent and a noble metal catalyst are charged into a pressurized reactor and then hydrogen gas is supplied until the pressurized state is obtained, and then raw material maleic anhydride or maleic acid is added to the reactor. In the method for producing succinic acid in which hydrogenation reaction is carried out, 10% by weight or more of maleic anhydride or maleic acid to be added to the pressure reactor is added by a sequential addition method. Lies in the way.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the highly purified succinic acid which suppressed the byproduct of malic acid is provided.

  Hereinafter, the present invention will be described in detail.

  In the method for producing succinic acid according to the present invention, an aqueous solvent and a noble metal catalyst are charged into a pressurized reactor and then hydrogen gas is supplied until the pressurized state is reached, and then the raw material maleic anhydride or maleic acid is supplied to the reactor. It is a batch type system in which hydrogenation reaction is carried out by adding.

  As maleic anhydride and maleic acid used as raw materials, commercially available products can be used. When maleic acid is used as a raw material, malic acid tends to be formed as a by-product more easily than when maleic anhydride is used as a raw material, and maleic acid is isomerized to produce fumaric acid. The time will be longer. Therefore, the use of maleic anhydride is recommended in the present invention.

  A conventionally well-known thing can be used as a noble metal catalyst used as a hydrogenation catalyst. Specific examples include palladium, rhodium, ruthenium, platinum and the like. Of these, palladium is particularly preferred. These may be used alone or in combination.

  Although the noble metal catalyst can be used as it is, an oxide such as silica, titanium, zirconia or a composite oxide thereof, activated alumina or activated carbon can be used as a support. These may be used alone or in combination. The amount of the noble metal supported is not particularly limited, but is usually 0.1 to 10% by weight as a ratio to the carrier. In addition, the precious metal catalyst which has been separated by filtration after completion of the hydrogenation reaction can be reused as it is as a hydrogenation catalyst for the next reaction. When the precious metal catalyst is charged into the reactor, it can be charged as it is or as a slurry of water.

  As hydrogen used in the hydrogenation reaction, a mixed gas with nitrogen, helium, argon, or the like can be used. However, in order to increase the partial pressure of hydrogen, it is preferable to use pure hydrogen gas.

  The pressure of the hydrogenation reaction is generally normal pressure to 5 MPa, preferably 0.3 to 1.0 MPa. If the hydrogen pressure is too low, the hydrogenation reaction takes a long time. On the other hand, if the hydrogen pressure is too high, the hydrogenation reaction time is not significantly shortened.

  In the present invention, it is preferable to replace the inside of the reactor with hydrogen gas before sequentially adding the raw materials to the pressurized reactor. When the filtrate is reused, it is preferable to replace the inside of the reactor while blowing hydrogen gas into the filtrate.

  The form of the raw material used for the hydrogenation reaction may be in a solid state or a molten state, but a molten state is preferable from the viewpoint of fluidity. The melting temperature is usually 60 to 120 ° C, preferably 80 to 100 ° C. If the melting temperature is too low, crystals will precipitate when added to the reactor and the reaction time will be longer, while if the temperature is too high, the amount of by-product malic acid will increase.

  The hydrogenation reaction temperature is preferably raised according to the sequential addition of raw materials. The initial temperature of the hydrogenation reaction is usually in the range of 20 to 60 ° C, preferably 30 to 50 ° C. When the initial temperature of the hydrogenation reaction is too low, maleic anhydride crystals are precipitated and the reaction time is prolonged. On the other hand, when the initial temperature is too high, the amount of by-product malic acid increases. The reaction temperature when the raw materials are sequentially added to advance the reaction is usually 90 to 120 ° C, preferably 100 to 110 ° C. If the reaction temperature is too low, the hydrogenation reaction takes a long time, while if the reaction temperature is too high, the amount of malic acid by-product increases. Since hydrogen is consumed as the hydrogenation reaction proceeds, the progress of the reaction can be known by monitoring the amount of hydrogen consumed by, for example, a change in the reaction pressure.

  The greatest feature of the present invention is that 10% by weight or more of the total amount of raw materials (maleic anhydride or maleic acid) added to the pressure reactor is sequentially added. Here, the sequential addition means continuous addition (a mode of adding over a certain time) or intermittent addition (a mode of split addition divided into a plurality of times) without adding all at once. The total amount of raw material added to the pressure reactor is appropriately determined in consideration of the capacity of the pressure reactor. When the ratio of the raw material added sequentially is less than 10% by weight, the effect of suppressing by-product malic acid is not sufficient. The ratio of the raw material added by the sequential addition method is preferably 50 to 70% by weight in consideration of productivity.

  The addition time of the raw material in the case of continuously adding continuously varies depending on conditions such as reaction temperature and reaction pressure, but is usually 1 to 4 hours, preferably 2 to 3 hours. That is, it is continuously added at a constant rate over these times. When the addition time is too short, the effect of suppressing malic acid by-product is not sufficient. Further, since the hydrogenation reaction is an exothermic reaction, it is difficult to remove the heat of reaction, the reaction temperature becomes too high, and malic acid is easily produced as a by-product. On the other hand, when the addition time is too long, the time for the hydrogenation reaction becomes long and is not efficient.

  The number of divisions of the raw material in the case of intermittent sequential addition is usually 3 to 10 times, preferably 4 to 7 times, although it depends on the conditions such as reaction temperature and reaction pressure as well as the ratio of the raw materials used for sequential addition. Yes, the interval may be based on the termination of the hydrogenation reaction, but in terms of time, it is usually 5 to 60 minutes, preferably 10 to 30 minutes.

  In order to complete the hydrogenation reaction after the sequential addition of the raw materials is completed, it is usually preferable to continue the reaction state for about 0.5 to 2 hours. The time required for the hydrogenation reaction cannot be generally determined, but the hydrogenation reaction ends when the consumption of hydrogen stops.

  After completion of the hydrogenation reaction, the hydrogenation catalyst is separated from the succinic acid-containing reaction solution by an operation such as filtration, and then succinic acid is crystallized by cooling or the like, and the succinic acid crystals are separated by filtration. During filtration, if the filtrate remains in the succinic acid cake, the purity of the succinic acid will decrease. Is preferred.

  In the present invention, the filtrate after filtering off the succinic acid cake can be reused in the next reaction. The reason is that the concentration of succinic acid and malic acid in the filtrate converges to a substantially constant concentration as the batch is repeated. The concentration of succinic acid and malic acid in the filtrate does not affect the conversion rate of succinic acid and malic acid during the hydrogenation reaction, but depends on the reaction temperature, reaction pressure, amount of hydrogenation catalyst used, etc. It is.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited by these Examples, unless the summary is exceeded.

<Example 1>
A stainless steel autoclave having an internal volume of 1 liter is charged with 46 g of maleic anhydride and 375 g of water. To this was added 1.4 g (containing 50 wt% water) of powdered activated carbon carrying 5 wt% palladium as a hydrogenation catalyst. The air gap in the autoclave was replaced with nitrogen, stirred at 300 rpm using a turbine blade stirring blade, and heated to 50 ° C. Stirring was stopped, the void of the autoclave was replaced with hydrogen, and the internal pressure of the autoclave was adjusted to 0.35 MPa (gauge pressure), and then the reaction was started by stirring at 1200 rpm. Next, 131 g of maleic anhydride was previously heated to 80 ° C. to be in a molten state, and the entire amount of the melt was successively added continuously at a constant rate over 3 hours. As the melt was added, the temperature in the autoclave increased, and when it reached 100 ° C, the autoclave was cooled and adjusted to 100 ° C. After the addition of the melt was completed, the reaction was further continued for 0.5 hours to complete the hydrogenation reaction. Next, the hydrogen gas in the autoclave was released to return to normal pressure, and the voids were replaced with nitrogen gas. Thereafter, 560 g of water was added for dilution, and the hydrogenation catalyst in the reaction solution was separated using a filter to obtain a clear succinic acid-containing reaction solution. The components of this succinic acid-containing reaction solution were analyzed by high performance liquid chromatography, and the reaction yield of succinic acid and malic acid was calculated. The calculation results are shown in Table 1 together with the ratio of maleic anhydride subjected to sequential addition.

<Example 2>
A stainless steel autoclave having an internal volume of 1 liter is charged with 75 g of maleic anhydride and 375 g of water. To this was added 1.4 g (containing 50 wt% water) of powdered activated carbon carrying 5 wt% palladium as a hydrogenation catalyst. The air gap in the autoclave was replaced with nitrogen, stirred at 300 rpm using a turbine blade stirring blade, and heated to 50 ° C. Stirring was stopped, the void of the autoclave was replaced with hydrogen, and the internal pressure of the autoclave was adjusted to 0.35 MPa (gauge pressure), and then the reaction was started by stirring at 1200 rpm. One hour after the start of stirring, 106 g of maleic anhydride was heated in advance to 80 ° C. to be in a molten state, and the entire amount of the melt was continuously added continuously at a constant rate over 2 hours. As the melt was added, the temperature in the autoclave increased, and when it reached 100 ° C, the autoclave was cooled and adjusted to 100 ° C. After the addition of the melt was completed, the reaction was further continued for 0.5 hours to complete the hydrogenation reaction. Next, the hydrogen gas in the autoclave was released to return to normal pressure, and the voids were replaced with nitrogen gas. Thereafter, 560 g of water was added for dilution, and the hydrogenation catalyst in the reaction solution was separated using a filter to obtain a clear succinic acid-containing reaction solution. The components of this succinic acid-containing reaction solution were analyzed by high performance liquid chromatography, and the reaction yield of succinic acid and malic acid was calculated. The calculation results are shown in Table 1 together with the ratio of maleic anhydride subjected to sequential addition.

<Example 3>
The reaction was carried out in the same manner as in Example 1 except that 0 g of maleic anhydride charged in the autoclave was changed to 173 g of a molten solution of maleic anhydride added during the reaction. Components of the obtained succinic acid-containing reaction solution were analyzed by high performance liquid chromatography, and the reaction yield of succinic acid and malic acid was calculated. The calculation results are shown in Table 1 together with the ratio of maleic anhydride subjected to sequential addition.

<Example 4>
The reaction was carried out in the same manner as in Example 2, except that 100 g of maleic anhydride charged in the autoclave was changed to 75 g of the molten maleic anhydride solution added during the reaction. Components of the obtained succinic acid-containing reaction solution were analyzed by high performance liquid chromatography, and the reaction yield of succinic acid and malic acid was calculated. The calculation results are shown in Table 1 together with the ratio of maleic anhydride subjected to sequential addition.

<Comparative Example 1>
A stainless steel autoclave having an internal volume of 1 liter is charged with 176 g of maleic anhydride and 375 g of water. To this was added 1.4 g (containing 50 wt% water) of powdered activated carbon carrying 5 wt% palladium as a hydrogenation catalyst. The air gap in the autoclave was replaced with nitrogen, stirred at 300 rpm using a turbine blade stirring blade, and heated to 50 ° C. Stirring was stopped, the void of the autoclave was replaced with hydrogen, and the internal pressure of the autoclave was adjusted to 0.31 MPa (gauge pressure). The reaction was completed. When the temperature in the autoclave rose to 100 ° C, the autoclave was cooled and adjusted to 100 ° C. The reaction pressure was further reacted for 0.5 hour after the addition of the melt was completed to complete the hydrogenation reaction. Next, the hydrogen gas in the autoclave was released to return to normal pressure, and the voids were replaced with nitrogen gas. Thereafter, 560 g of water was added for dilution, and the hydrogenation catalyst in the reaction solution was separated using a filter to obtain a clear succinic acid-containing reaction solution. The components of this succinic acid-containing reaction solution were analyzed by high performance liquid chromatography, and the reaction yield of succinic acid and malic acid was calculated. The calculation results are shown in Table 1 together with the ratio of maleic anhydride subjected to sequential addition.

Claims (4)

  After supplying an aqueous solvent and a noble metal catalyst to the pressurized reactor, hydrogen gas is supplied until the pressurized state is reached, and then the raw maleic anhydride or maleic acid is added to the reactor to perform the hydrogenation reaction. In the method for producing acid, a method for producing succinic acid, comprising adding 10% by weight or more of maleic anhydride or the total amount of maleic acid added to the pressure reactor by a sequential addition method.   The method for producing succinic acid according to claim 1, wherein the raw material is maleic anhydride.   The method for producing succinic acid according to claim 1 or 2, wherein the hydrogenation reaction temperature is in the range of 70 to 120 ° C.   The method for producing succinic acid according to any one of claims 1 to 3, wherein the noble metal catalyst is a palladium catalyst or a ruthenium catalyst.