KR20060078286A - Device and method for acetic acid and catalyst recovery in process for preparation of 2,6-naphthalenedicarboxylic acid - Google Patents

Abstract

In the continuous process of oxidizing dimethyl naphthalene using a catalyst system prepared using a bromine compound and a transition metal such as cobalt and manganese under an oxygen-containing gas and an acetic acid solvent, oxidation of a naphthalenedicarboxylic acid is carried out. The present invention relates to an apparatus and a method for effectively recovering acetic acid and catalyst from mother liquor discharged through a process, a crystallization process, and a solid-liquid separation process.

Naphthalenedicarboxylic acid, dimethylnaphthalene, acetic acid, catalyst, recovery device

Description

Device and method for acetic acid and catalyst recovery in the production process of 2,6-naphthalenedicarboxylic acid {Device and Method for Acetic Acid and Catalyst Recovery in Process for Preparation of 2,6-Naphthalenedicarboxylic Acid}

FIG. 1 is a schematic diagram of an apparatus for recovering acetic acid and a catalyst from a mother liquor discharged from a 2,6-naphthalenedicarboxylic acid manufacturing process according to an embodiment of the present invention.

* Explanation of Reference Numbers

A. Mother liquor receiver B. Stirrer

1. Mother liquor inlet 2. Catalyst and organics outlet

3. Acetic acid outlet 4. Calorie supply

5. Condensate outlet 6. Caustic soda inlet

7. Lower filtration membrane

The present invention is a continuous process of oxidizing dimethyl naphthalene using a catalyst system prepared using a transition metal such as cobalt, manganese and bromine compounds in an oxygen-containing gas and acetic acid solvent to produce naphthalenedicarboxylic acid, The present invention relates to an apparatus and a method for effectively recovering acetic acid and a catalyst from a mother liquor discharged through an oxidation process, a crystallization process, and a solid-liquid separation process.

In general, various separation processes may be used to recover the acetic acid and catalyst used in the process.

The acetic acid recovery process using distillation is a common but economically disadvantageous method, and the filtration and absorption methods are not suitable for separating acetic acid and catalyst. Thus, several different methods for recovering acetic acid and catalyst have been proposed. U.S. Patent No. 4,883,912 shows a process for recovering acetic acid by an extraction method using tethiari amine and an organic diluent as an extraction solvent of acetic acid in an acetic acid solution containing a metallic material. However, such a method is not suitable as a method of recovering acetic acid and a catalyst in the manufacturing process of naphthalenedicarboxylic acid. This is because the extraction method should be separated after the recovery of acetic acid, the post-treatment process, and the reactivity of the extraction solvent and the oxidation catalyst should be considered.

Catalyst recovery methods include incineration, vacuum filtration, and electrochemical methods, but have not been commercialized.

Accordingly, the present invention has been made in an effort to provide an apparatus and a method for most efficiently and efficiently recovering acetic acid and a catalyst from a mother liquor discharged from a manufacturing process of naphthalenedicarboxylic acid in order to solve the above problems and disadvantages of the prior art.

The present invention relates to an acetic acid and catalyst recovery apparatus and method, comprising an apparatus for recovering acetic acid and catalyst in the mother liquor discharged from the manufacturing process of naphthalenedicarboxylic acid to achieve the above object,

A mother liquor receiving portion having a mother liquor or caustic soda inlet and an acetic acid outlet at the top and a catalyst and an organic outlet at the bottom;

Heating means for heating the mother liquid container;

A lower filtration membrane connected to the catalyst and the organic material outlet for separating the catalyst from the organic material; And

Acetic acid from the mother liquor containing the acetic acid, catalyst and other organic matter discharged in the manufacturing process of naphthalenedicarboxylic acid, characterized in that it comprises a stirrer for stirring the inside of the mother liquor receiving portion and is in the shape of a conical or truncated cone And / or an apparatus for catalyst recovery.

In another aspect, the present invention relates to a device for acetic acid and / or catalyst recovery, characterized in that the means for heating the mother liquor receiving unit is attached to the outer wall of the mother liquor receiving unit with a jacket having a steam inlet and a condensate discharge port for using the calorie medium. will be.

In another aspect, the present invention comprises the steps of receiving a mother liquid discharged after the separation process of the NDA produced in the manufacturing process of naphthalenedicarboxylic acid (NDA);                     

Heating the contained mother liquor to recover acetic acid as a gas; And

It relates to a method for recovering acetic acid and / or catalyst from the mother liquor discharged after the separation process of NDA consisting of the step of recovering the acetic acid to precipitate the catalyst by adding caustic soda to the remaining residue to recover the catalyst.

Hereinafter, the present invention will be described in detail with reference to FIG. 1 which is a schematic diagram of an embodiment of the present invention.

The mother liquid inlet 1 is provided in the upper part of the mother liquid receiving part A, and accommodates the mother liquid discharged | emitted in the manufacturing process of naphthalenedicarboxylic acid. The housed mother liquor is heated by an external heating means, at which time acetic acid is vaporized and discharged to the acetic acid outlet 3. The residue left after acetic acid is discharged consists of a catalyst and other organic substances, and caustic soda is added to the residue to precipitate the catalyst. The caustic soda may be introduced through a separate inlet 6 but may also be introduced into the mother liquor inlet 1. The precipitated catalyst is discharged through the catalyst and the organic outlet, and then separated and recovered with the organic matter through the lower filtration membrane (7).

The mother liquor accommodating portion is provided with a stirrer (B) for stirring the mother liquor or the catalyst-containing residue, and the stirrer is preferably anchored.

For example, the mother liquor heating means heats the mother liquor in the mother liquor accommodating part by accommodating steam at 170 to 190 ° C. in the calorific supply 4, and the introduced steam is condensed and discharged to the lower condensate outlet 5.

As a catalyst used to oxidize dimethylnaphthalene to naphthalenedicarboxylic acid, a complex catalyst system consisting of a combination of cobalt component, manganese component and bromine component is used. Cobalt carbonate and the like, and the amount of the cobalt component is 0.02 to 0.15, preferably 0.04 to 0.12, and more preferably 0.06 to 0.1 in the ratio of cobalt atoms to dimethylnaphthalene.

Compounds that can be used as the manganese component are manganese acetate, manganese phthalate, manganese carbonate, manganese bromide, and the amount of manganese component is 0.05 to 1.0, preferably 0.15 to 0.4 based on the cobalt atom. The amount of total metal catalyst, ie, the sum of cobalt and manganese components, is 0.03 to 0.25, preferably 0.05 to 0.2, relative to dimethylnaphthalene on an atomic basis. If it is out of the above range, the desired high purity naphthalenedicarboxylic acid cannot be obtained. If too little cobalt and manganese components are used, conversion of 2,6-formylnaphthoic acid, which is an intermediate of the oxidation reaction, is not achieved. The yield of the product is lowered, and when used too much, it forms a complex with an impurity trimellitic acid, which reduces the purity of naphthalenedicarboxylic acid.

One or more compounds selected from the group consisting of manganese bromide, cobalt bromide, sodium bromide, ammonium bromide and tetrabroethane can be used for the provision of the bromine component, and the proportion of the bromine component is 0.8 to 2.0, preferably based on cobalt atoms. Is 1.0 to 1.5. When the bromine component above the above range is used, the amount of finally induced transition metal complex of naphthalenedicarboxylic acid decreases, but the amount of bromine compound increases, which increases the load of the purification process and increases the color impurities. not. In addition, if the process of reusing the bromine component is adopted, additional economic losses occur due to the need for a recovery process. On the other hand, when using the bromine component below the above range, the amount of the transition metal complex in the naphthalenedicarboxylic acid is increased.

The reactant, dimethylnaphthalene, is dissolved in acetic acid at a ratio of 1: 5 to 1:15, preferably in a ratio of 1:10 to 1:12, and introduced into an oxidation reactor.

The product, which has undergone the oxidation reaction, is passed through the crystallization process to a solid-liquid separation process in the form of a slurry of solid phase and acetic acid having crystals of a predetermined size, and is a solid phase product and mother liquor, that is, a catalyst and an organic substance by a separation process apparatus. It is separated into this containing acetic acid solution. An object of the present invention is to separate acetic acid and catalyst in a mother liquor that has undergone a solid-liquid separation process in an effective manner.

Through the acetic acid and catalyst recovery apparatus of the present invention, acetic acid is recovered by evaporation by adding steam, which is a calorific medium, and the catalyst in the non-evaporated solution is precipitated by adding caustic soda, and then recovered by vacuum filtration.

The acetic acid and catalyst recovery apparatus of the present invention is characterized in that the jacket is attached to the outer wall to use the calorie medium as a mother liquid heating means for acetic acid evaporation.

In addition, caustic soda is preferably added two to three times as much residual acetic acid as is suitable for neutralizing the remaining acetic acid and organics.

In addition, the total filtration area used in the vacuum filtration method is 0.3 to 0.7 m 2, the size of the filtration membrane is 20 to 80 μm, and the degree of vacuum is maintained at 50 to 150 mmHg.

Hereinafter, the present invention will be described in more detail with reference to examples, but these examples should not be considered as limiting the present invention.

Example 1

Into a 300L titanium oxidation reactor equipped with a cooler, a heater, a stirrer and a recycle acetic acid drum, the catalyst and the reactants of the composition ratio as shown in Table 1 are added together.

<Table 1>

 cobalt 6.21 wt% manganese 1.58 wt% bromine 3.87 wt% Distilled water 25.0 wt% Acetic acid balance

The reaction temperature is 200 ℃, the reaction pressure is adjusted to 20 kg / cm ² and then set the stirrer to 700rpm to properly disperse the introduced reactor. The reaction proceeds continuously while supplying a reaction solution having a weight ratio of dimethylnaphthalene to acetic acid of 10% with a catalyst at a rate of 93 kg / hr.

After the reaction, the mother liquor discharged through the crystallization step and the separation step is introduced into the acetic acid and catalyst recovery device. The acetic acid and catalyst recovery device is made of stainless steel having an internal volume of 107 L. The outer wall includes a jacket through which a medium for supplying heat is moved, and an anchor type stirrer is installed inside. As a medium to supply heat, steam of 10 atm is used until acetic acid evaporates more than 70%. After evaporation of acetic acid, 50 L of caustic soda is added while maintaining the temperature at 60 ° C. After 2 hours, the filter and the vacuum pump are connected to the catalyst and the organic outlet, the organic and the solution are filtered and the remaining catalyst is recovered.

Cobalt catalyst metal recovery was 95%, manganese catalyst metal recovery was 90%, bromine recovery was 10%, and acetic acid recovery was 65%.

As mentioned above, according to the Example, when acetic acid and a catalyst were collect | recovered through the apparatus of this invention, it was confirmed that it is very economically advantageous.

As described in detail above, the present invention constitutes a process for recovering acetic acid and catalyst in the mother liquor discharged from the manufacturing process of naphthalenedicarboxylic acid in order to secure economical efficiency, and at the same time recyclable acetic acid and catalyst without a separate purification process Has the effect of providing.

Claims (6)

A mother liquor receiving portion having a mother liquor or caustic soda inlet and an acetic acid outlet at the top and a filtration catalyst and an organic outlet at the bottom; Heating means for heating the mother liquid container; A lower filtration membrane connected to the catalyst and the organic outlet for separating the catalyst from the organics; And From the mother liquor containing the acetic acid, the catalyst and other organic matter, which is discharged in the manufacturing process of naphthalenedicarboxylic acid, comprising a stirrer for stirring the inside of the mother liquor receiving portion, characterized in that the conical or truncated conical shape Apparatus for acetic acid and / or catalyst recovery. 2. The apparatus for acetic acid and / or catalyst recovery according to claim 1, wherein the means for heating the mother liquor accommodating unit has a jacket having a steam inlet and a condensate outlet for using a calorific medium on the outer wall of the mother liquor accommodating unit. . 2. The apparatus for acetic acid and / or catalyst recovery according to claim 1, wherein the mother liquor receiving portion has a caustic soda inlet separately and uses a caustic soda and a filtration vacuum method to recover the catalyst. 4. The apparatus for acetic acid and / or catalyst recovery according to claim 3, wherein the amount of caustic soda is two to three times the residual acetic acid. The apparatus for recovering acetic acid and / or catalyst according to claim 1, wherein the lower filtration membrane has a degree of vacuum of 50 to 150 mmHg, a total filtration area of 0.3 to 0.7 m 2, and a size of 20 to 80 μm of the size of the filtration membrane. Receiving a mother liquor discharged after the separation process of NDA produced in the process for producing naphthalenedicarboxylic acid; Heating the contained mother liquor to recover acetic acid as a gas; Recovering acetic acid and / or catalyst from the mother liquor discharged after the separation process of naphthalenedicarboxylic acid consisting of the step of recovering the acetic acid is precipitated by the addition of caustic soda to the remaining residue after recovering the acetic acid.

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