JPH0611724B2 - Process for producing succinic acid - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for hydrogenating maleic anhydride or maleic acid using a noble metal catalyst to produce succinic acid.

[Prior Art] As a method for producing succinic acid, a method for hydrogenating maleic anhydride or maleic acid in an aqueous medium using a noble metal catalyst is described in, for example, JP-B-44-29246. In this method, for example, after hydrogenating maleic acid, the catalyst is collected by filtration while hot, the filtrate is cooled to crystallize succinic acid, the succinic acid crystals are filtered off, and the mother liquor is hydrogenated again. It is recycled and used as an aqueous medium for the hydrogenation reaction in the hydrogenation reaction of maleic acid together with the recovered catalyst.

[Problems to be Solved by the Invention] As a catalyst used in this hydrogenation reaction, a noble metal such as platinum or rhodium is used, which is extremely expensive. Therefore, it is preferable that the catalyst retains its activity as long as possible. However, when the circulation and reuse of the catalyst is repeated in the above method, the activity of the catalyst gradually decreases (deactivation), the time required for hydrogenation increases, and finally it becomes impossible to reuse it as a catalyst in practical use. It will be replaced with a new catalyst.

An object of the present invention is to prevent deactivation of the noble metal catalyst used in the above hydrogenation reaction and to enable long-term circulation and reuse of the catalyst.

The present inventors have made extensive studies on the deactivation of the catalyst in the hydrogenation reaction, and the cause is poisoning by the impurities contained in the raw material maleic anhydride or maleic acid. It was found that the deactivation of the catalyst can be prevented.

It is not always clear what kind of compound is the impurity that causes the deactivation of the catalyst, but for example, a polycondensate of maleic acid, or a copper compound added as a coloring inhibitor of maleic anhydride is used. Conceivable.

[Means for Solving Problems] The present invention achieves its object by using an ion exchange resin for treating impurities contained in these raw materials.

That is, the present invention is a method for producing succinic acid by hydrogenating maleic anhydride or maleic acid in an aqueous medium using a noble metal catalyst, after treating maleic anhydride or maleic acid with a cation exchange resin in advance, hydrogen A method for producing succinic acid, which comprises subjecting to succinic acid.

Maleic anhydride or maleic acid used as a raw material in the present invention is generally a C4 fraction such as butene and butadiene, butane, or one produced by a catalytic gas phase oxidation reaction of benzene, or a catalytic gas of ortho-xylene. Maleic anhydride and maleic anhydride, which are by-products in the production of phthalic anhydride by a phase-oxidation reaction, may be mentioned. In particular, maleic anhydride, which is usually commercially available, contains various chemicals in addition to impurities during production, in order to prevent deterioration and discoloration of maleic anhydride during storage, which poisons the catalyst. It is considered that the process according to the present invention is necessary and effective because it is considered to be a problem.

As the cation exchange resin used in the present invention,
Sulfonic acid (R-SO ₃ H) strong acid cation exchange resin or acrylic acid (R-COOH), phenol (R-OH), phosphonic acid (R-PO ₃ H ₂ ) or phosphonous acid (R-PO
₂ H) -based medium weak acid cation exchange resins,
Generally, a widely used widely used strong acidic cation exchange resin is used.

As a method for treating maleic anhydride or an aqueous maleic acid solution with a cation exchange resin, a known method generally used when an ion exchange resin is applied, for example, continuous one-stage or multi-stage dropping, fluidized bed, etc. However, a packed tower is usually selected. Of course, if necessary, it is possible to perform processing in a batch system (batch system).

As the treatment conditions by the packed column in the present invention, when treating maleic anhydride with a cation exchange resin, the treatment temperature is required because the maleic anhydride is liquid, so that its melting point (52.8 ° C.) or higher, Moreover, a temperature lower than the heat resistant temperature of the cation exchange resin is adopted. That is, generally 120 ° C or less, usually 60 to 100 ° C, and SV (space velocity) is generally 1 to 1
It is 5 hr ^-1 , usually 2 to 10 hr ^-1 . When treating the maleic acid aqueous solution with the cation exchange resin, basically the same treatment conditions can be used, but due to the difference in liquidity, the concentration of maleic acid should be below the saturation concentration, usually 20 to 50%. , The processing temperature is above room temperature, but below the heat resistance temperature of cation exchange resin, usually
Temperatures of 50-100 ° C are adopted. The SV may be almost the same as above. The pressure during treatment is not particularly limited,
You may pressurize at normal pressure.

The amount of maleic anhydride or maleic acid treated cannot be clarified because it depends significantly on the exchange capacity of the cation exchange resin and the type or amount of impurities in the raw material, but it is a standard that is generally adopted. It can be easily determined by detecting leakage of cations, for example, copper ions, or by reducing the reaction rate (hydrogen absorption rate) in the hydrogenation reaction of the raw material after treatment.

When maleic anhydride or a maleic acid raw material treated according to the present invention is used, the method of hydrogenating a succinic acid with a noble metal catalyst is carried out by a known method. For example, a concentration of about 30
-50% maleic acid and / or maleic anhydride aqueous solution at a temperature of about 80-100 ° C under hydrogen pressure, usually 2-30 Kg /
The catalyst is hydrogenated in cm ² G in an abundance ratio of a noble metal catalyst, and after the reaction, the catalyst is filtered while hot, the filtrate is cooled, and the precipitated succinic acid crystals are separated by filtration and dried, while the catalyst and The filtrate is recycled to the reaction under hydrogen. Since the by-product accumulates in the filtrate, it is usually partially discharged, but in the present invention, since the impurities in the raw material have already been treated, the by-product itself in the circulating mother liquor is less accumulated. It is possible to control the accumulation of impurities in the recirculating liquid by treating the product with a cation exchange resin and recycling it.

Examples of the noble metal catalyst used in the present invention include catalysts such as palladium, ruthenium, rhodium, and platinum. Generally, these noble metals are supported on activated carbon, silica, alumina, silica-alumina, or the like, or The oxide is used, for example, a loading rate of 2%, 5% or 10
% Palladium-carbon (Pd-C), 5% ruthenium-carbon (R
uC), 5% rhodium-carbon (Rh-C) or platinum oxide. Usually, Pd-C is used, which is cost-effective, highly selective, and highly resistant to poisoning.

The amount of the catalyst used is generally 0.01 to maleic acid.
2%, usually 0.1-1%.

[Operation and Effect of the Invention] In the production of succinic acid, the present invention poisons the noble metal catalyst used in the hydrogenation reaction by previously treating the raw material maleic anhydride or maleic acid with a cation exchange resin. Since the impurities are removed, deactivation of the catalyst is prevented and the catalyst activity can be maintained for a long period of time. Further, by treating the circulating mother liquor in the hydrogenation reaction with a cation exchange resin, the catalyst life can be further extended, and the catalyst cost in the production of succinic acid can be significantly reduced.

[Examples] Hereinafter, the method of the present invention will be described in detail with reference to Examples.
Deterioration of poisoning of the noble metal catalyst in the hydrogenation reaction requires a long time because the catalyst is repeatedly used. Therefore, the forced poisoning treatment test method described below was adopted as a method capable of relatively comparing the decrease in catalyst activity due to repeated use.

Note that "%" and "part" used in this specification
Means "% by weight" and "parts by weight" unless otherwise specified.
Indicates.

Forced poisoning treatment test method (1) Poisoning treatment Maleic anhydride or maleic acid to be tested 200
Part (2000 times the catalyst) is placed in a container, and 300 parts of pure water is added and dissolved. Poisoning treatment is performed by adding 0.1 part of 5% Pd-C as a catalyst and stirring at 95 ° C. for 3 hours in a nitrogen atmosphere. After hot filtration and washing 5 times with 20 parts of warm water, the catalyst obtained is dried at 65 ° C.

(2) Hydrogenation reaction experiment Commercially available maleic anhydride 10 g was taken in an autoclave equipped with a stirrer and a constant-pressure hydrogen introduction pipe, and 100 g of pure water was put,
Dissolve under stirring at 60 ° C for 10 minutes. Next, 0.045 g of the catalyst poisoned by (1) was added, and the mixture was stirred at 80%, 8 Kg / cm ²
Measure the rate of hydrogen absorption with G.

As a control, the hydrogen absorption rate was measured in the same manner using a new catalyst, and used as a criterion for determining the activity decrease due to the poisoning treatment.

Example 1 and Comparative Example 1 A control cock is provided at the bottom and a maleic anhydride solution is provided at the top at 80 ° C.
Equipped with a separatory funnel that can keep warm, and heated to 80 ℃
A glass packed tower of 0.2 mm and a height of 720 mm was filled with 53 ml of a strongly acidic cation exchange resin (polystyrene / sulfonic acid cation exchange resin manufactured by Mitsubishi Kasei Co., Ltd., Diaion-PK-228L).

When copper ion as an indicator was selected and a commercially available maleic anhydride used as a raw material was analyzed, the content was 0.11 ppm. This maleic anhydride was placed in the above separating funnel, and the maleic anhydride solution at 80 ° C. was passed through the packed bed of the cation exchange resin at SV1 to 10 hr ⁻¹ . A total of about 3,700 g of maleic anhydride was treated, and the analytical value of copper as an indicator was about 0.01 ppm or less in any SV.

Using the cation exchange resin-treated maleic anhydride according to the above and untreated maleic anhydride as a comparative example,
The above-mentioned forced poisoning treatment test method was applied, and the hydrogen absorption rate of the hydrogenation reaction of the poisoned catalyst was measured by the arrival times of the reaction rates of 50%, 90% and 100%. The results are shown in Table 1.

As a result, the hydrogenation reaction time by the catalyst forcibly poisoned by the treated maleic anhydride was 13 minutes at 50% reaction rate, 27 minutes at 90%, and 33 minutes at 100%. There was virtually no difference from the catalyst, and no activity decrease due to poisoning of the catalyst was observed.

On the other hand, the catalyst poisoned with untreated maleic anhydride has a low hydrogenation reaction rate, and the activity is reduced due to poisoning.

The succinic acid obtained by the hydrogenation reaction according to the present invention was obtained by high-purity succinic acid by filtering the catalyst while hot according to a conventional method, crystallizing succinic acid from the filtrate, filtering and drying. .

Example 2 Instead of 100 parts of maleic anhydride in Example 1, commercially available maleic anhydride was dissolved in pure water to obtain 40% of maleic acid.
A cation exchange resin treatment was performed in the same manner using 250 parts of the solution, and the obtained maleic acid aqueous solution was subjected to the forced poisoning treatment test method in the same manner as in the method of Example 1, and Almost similar results were obtained.

Example 3 100 parts of a commercially available maleic anhydride treated with a cation exchange resin in the same manner as in Example 1 was placed in an autoclave equipped with a stirrer and a hydrogen inlet tube of constant pressure, and 200 parts of pure water was added and stirred. It melted down. Then, add 0.5 parts of 5% Pd-C,
The hydrogenation reaction was carried out at 80 ° C. and 8 kg / cm ² G with stirring.
When the hydrogen absorption was stopped, the reaction was stopped, the catalyst was filtered while hot, the filtrate was cooled, and the precipitated succinic acid was filtered and dried to obtain high-purity succinic acid.

The mother liquor and the catalyst were repeatedly used again in the hydrogenation reaction under the above conditions. Thus, the catalyst was subjected to the reaction 50 times repeatedly, but the activity of the catalyst was hardly reduced, and there was no practical problem. On the other hand, in the case of using the untreated commercially available maleic anhydride as a raw material and circulating the catalyst in the same manner as above,
From about the 25th time, the hydrogen absorption rate decreased remarkably, and it took a long time to achieve the reaction rate of maleic acid of 100%, which made it practically impossible to use.

Claims (5)

[Claims] 1. A method for producing succinic acid by hydrogenating maleic anhydride or maleic acid in an aqueous medium using a noble metal catalyst, wherein maleic anhydride or maleic acid is previously treated with a cation exchange resin, and then hydrogen is added. A method for producing succinic acid, which comprises subjecting to succinic acid. 2. The process for producing succinic acid according to claim 1, wherein the maleic anhydride is treated with the cation exchange resin in a molten state above its melting point and below the heat resistant temperature of the cation exchange resin. . 3. The method for producing succinic acid according to claim 1, wherein the aqueous maleic acid solution is treated with a cation exchange resin. 4. The succinic acid according to any one of claims 1 to 3, wherein after the completion of the hydrogenation reaction, the mother liquor from which the crystallized succinic acid is separated is circulated in the hydrogenation reaction as an aqueous medium. Manufacturing method. 5. The circulating mother liquor is treated with a cation exchange resin,
The method for producing succinic acid according to any one of claims 1 to 4.