JP2010248090A - Oxidation reactor, and method of producing aromatic polycarboxylic acid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxidation reactor for industrially producing a high-quality aromatic polycarboxylic acid at a high yield capable of suppressing quick and uniform mixing of raw materials, the by-production of a compound of a high boiling point, and the production of an intermediate, upon oxidizing polymethylbenzaldehyde in a liquid phase by air, and a method of producing an aromatic polycarboxylic acid. <P>SOLUTION: The reactor for use in liquid-phase oxidation including a jacket 18 disposed on the circumference of the body of the reactor, an agitation shaft 4 of a concentric agitation type disposed inside the body of the reactor, with a pair of agitation blades 2 attached thereto and with a rotary atomizer 3 attached to the bottom thereof, and a pair of partitioning discs 1 dividing the inner space of the reactor into three sections A, B, and C, is characterized in that the section A is equipped with a feed port 5 for feeding a catalyst and a solvent thereinto, the section B is equipped with a feed port 6 for feeding raw materials thereinto, and the section C is equipped with a feed port 7 for feeding molecular oxygen thereinto and a discharge port 8 for discharging a reaction liquid therefrom. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

    The present invention relates to an oxidation reactor and a method for producing an aromatic polycarboxylic acid by liquid phase air oxidation of polymethylbenzaldehyde using this oxidation reactor.

    Conventionally, aromatic polycarboxylic acid from 2,4-dimethylbenzaldehyde and 2,4,5-trimethylbenzaldehyde by bromide ion and heavy metal (eg manganese) ion as catalyst, water as solvent and molecular phase oxidation with molecular oxygen. Technology for producing acid, and 2,4-dimethylbenzaldehyde, 2,5-dimethylbenzaldehyde, 3,4-dimethylbenzaldehyde, 2,4-dimethylbenzoic acid, 2,5-dimethylbenzoic acid, 3,4-dimethyl Many techniques for producing trimellitic acid from benzoic acid have been known (see, for example, Patent Documents 1 and 2).

    On the other hand, a technique for producing polyalkylbenzoic acid using a rotary atomizer as a means for blowing molecular oxygen when liquid phase oxidation of polyalkylbenzaldehyde with molecular oxygen is also disclosed (see Patent Document 3). However, the structure of these reactors is a general complete mixing type, and the raw material supplied to the reactor is quickly and uniformly mixed in the reactor, so that the composition in the reactor is equal to the composition of the extracted fluid. there were.

    Also, in the case of producing a high-purity aromatic polycarboxylic acid using polymethylbenzaldehyde as a raw material, the complete mixing system of the prior art suppresses by-product formation of high-boiling compounds in the initial oxidation reaction, thereby generating intermediates. No specific means for suppressing the above and improving the yield of the target product is shown.

Japanese Patent Publication No.58-2222 Japanese Patent Laid-Open No. 2002-3440 Japanese Patent Publication No. 56-8816

  The object of the present invention is to suppress the rapid and uniform mixing of raw materials in the prior art when liquid phase air oxidation is performed using polymethylbenzaldehyde as a raw material, to suppress the production of by-products and intermediates of high-boiling compounds due to the suppression, An object of the present invention is to provide an oxidation reactor capable of industrially producing a high-quality aromatic polycarboxylic acid with high yield and a method for producing an aromatic polycarboxylic acid using the reactor.

The present inventors, for liquid phase air oxidation in an aqueous solvent using molecular oxygen from polymethylbenzaldehyde as a raw material, when oxidizing polymethylbenzaldehyde in the conventional complete mixing formula, the functional group most easily oxidized The formyl group is difficult to convert to polymethylbenzoic acid with good selectivity, resulting in problems such as the formation of high-boiling compounds, and finally earnest research focusing on the problems that aromatic polycarboxylic acids cannot be produced efficiently. As a result, the reactor internal space is divided into compartment (A), compartment (B), and compartment (C) by two partitioning discs (1). In compartment (A), the catalyst and solvent are separated. It is provided with a charging port (5), the compartment (B) is provided with a raw material charging port (6), and the compartment (C) is provided with a molecular oxygen charging port (7) and a reaction liquid outlet (8). Liquid phase oxidation characterized by It is of the reactor.

That is, the present invention
[A] the reactor body;
A jacket (18) is provided around the reactor body, a central stirring type stirring shaft (4) is provided inside the reactor body, and two stirring blades (2) are provided on the stirring shaft (4). ) And a rotary atomizer (3) is connected to the bottom of the stirring shaft (4), and the internal space of the reactor is divided into two compartments (A) by two partition disks (1). ), Compartment (B) and compartment (C), and compartment (A) is provided with catalyst and solvent inlets (5), and compartment (B) is charged with raw materials (6). A reactor for liquid phase oxidation, wherein the compartment (C) is provided with a molecular oxygen charging port (7) and a reaction liquid outlet port (8).
[B] The vertical distance between the lower surface of the partition disk (1) and the bottom surface of the oxidation reactor is 0.9 × D to 1.5 × D (mm) (D is the inner diameter of the oxidation reactor (mm) )), The vertical distance between the lower surface of the partition disk (1) and the bottom surface of the oxidation reactor is 2.1 × D to 2.8 × D (mm) (D is the same as above) [A ] The reactor as described in.
[C] The lateral distance (clearance) between the stirring shaft (4) and the two partition disks (1) is 0.01 × D to 0.04 × D (mm) (D is the same as above) The reactor according to [A].
[D] The lateral distance (clearance) between the inner surface of the reactor and the two partition disks (1) is 0.01 × D to 0.04 × D (mm) (D is the same as above). The reactor according to [A].
[E] The rotary atomizer (3) is rotated by being connected to a central stirring type stirring shaft (4), and is positioned above the molecular oxygen charging port (7). Reactor.
[F] The reactor according to claim 1, wherein the jacket (18) functions as a heating means of the reactor.
[G] In the production method for producing an aromatic polycarboxylic acid by liquid phase oxidation reaction of polymethylbenzaldehyde, the reactor is the reactor for liquid phase oxidation according to any one of [A] to [F] A process for producing an aromatic polycarboxylic acid, characterized in that
[H] The method for producing a high-purity aromatic polycarboxylic acid according to [G], wherein the aromatic polycarboxylic acid is trimellitic acid or pyromellitic acid.

  Compared to the conventional complete mixing type oxidation reactor structure, by using the fractionation type oxidation reactor having three compartments according to the present invention, the oxidation of the formyl group at the initial stage is performed properly. Then, the oxidation reaction of the remaining functional groups can be oxidized with high selectivity, and an aromatic polycarboxylic acid can be obtained in high yield.

  When polymethylbenzaldehyde is used as a raw material and bromide ions and heavy metal (eg, manganese) ions are used as catalysts (hereinafter sometimes abbreviated as “catalyst”) in an aqueous solvent and air oxidation is performed in the liquid phase, By using a fractional oxidation type oxidation reactor having the following sections, it is possible to perform a sequential oxidation reaction and an extrusion type oxidation reaction by introducing a catalyst and a solvent from the upper part of the reactor and withdrawing the reaction liquid from the lower part of the reactor. Become. In addition, the use of a rotary atomizer enables the highly dispersed molecular oxygen to be blown, and by optimizing the air introduction position, the raw material introduction position, the catalyst and solvent introduction position, an industrially high yield. Aromatic polycarboxylic acids can be produced.

The present invention is described in detail below.
Compared with the conventional fully mixed oxidation reactor, when an oxidation reactor having three compartments is used, a fractional oxidation reaction, a catalyst and a solvent are introduced from the upper part of the reactor, and a reaction solution is introduced from the lower part of the reactor. Extraction enables the extrusion-type oxidation reaction, and the optimal formyl group oxidation of the raw material and the selective reaction to the target product proceed optimally, resulting in a decrease in the formation of high-boiling substances and intermediates. The inventors have found an oxidation reactor capable of industrially producing a high-quality, high-purity aromatic polycarboxylic acid with a high yield and few by-products, and have reached the present invention.

    In the conventional complete mixing formula, when polymethylbenzaldehyde is oxidized, the functional group that is most easily oxidized is a formyl group, but it is difficult to make polymethylbenzoic acid with good selectivity, and a high-boiling compound is by-produced. A malfunction occurs, and it is impossible to finally obtain an aromatic polycarboxylic acid efficiently. In addition, if the raw material polymethylbenzaldehyde and air are supplied from the same height position, the oxidation reaction does not proceed selectively and many high-boiling compounds are produced, resulting in a decrease in the yield of the target aromatic polycarboxylic acid. To do.

    By providing the partition disk of the present invention, the fractionation type oxidation reaction, the catalyst and the solvent are introduced from the upper part of the reactor, and the reaction liquid is withdrawn from the lower part of the reactor. By controlling the polymethylbenzaldehyde concentration in the vicinity of the inlet to be low, the oxidation of the formyl group selectively proceeds, and further oxidation proceeds while generating polymethylbenzoic acid, which is the initial stage, with high selectivity. A high purity aromatic polycarboxylic acid can be produced.

The lowest surface (0D) of the oxidation reactor will be described with reference to FIG.
The structure of the lower part of the oxidation reactor is based on two types: a simple mirror plate structure that is weak against internal pressure, and a semi-ellipsoidal mirror structure that is slightly complicated but resistant to internal pressure. That is, 0D on the lowest surface of the oxidation reactor is the position of the inner surface of the reactor lower plate in the case of the flat mirror plate structure, and the position of the lower tangential line (TL) in the semi-elliptical mirror structure. The lower tangential line refers to the boundary line between the straight body of the reactor and the lower semicircular mirror.

The structure of the oxidation reactor will be described with reference to FIG.
The oxidation reactor of the present invention has a reactor main body, a jacket (18) around the reactor main body, a central stirring type stirring shaft (4) inside the reactor main body, Two stirring blades (2) are connected to the stirring shaft (4), and a rotary atomizer (3) is connected to the bottom of the stirring shaft (4). The partition disk (1) is divided into three sections, that is, a section (A), a section (B), and a section (C). The section (A) is provided with a catalyst and solvent charging port (5). B) is a reactor for liquid phase oxidation having a raw material charging port (6) and a compartment (C) having a molecular oxygen charging port (7) and a reaction liquid outlet (8). .

The dimensions of the oxidation reactor will be described with reference to FIG. The detailed dimensions of each part are described in [1] to [5].
[1] A partition disk P-1 (where P-1 = 0.9 × D to 1.5 × D, where D is the inner diameter of the oxidation reactor (0D) above the bottom surface (0D) of the reactor) mm).) and a partition disk P-2 (where P-2 = 2.1 × D to 2.8 × D, D is the same as described above). The partition disk has a clearance α1 (α1 = 0.01 × D to 0.04 × D, D is the same as described above) between the stirring shaft and the clearance α2 ( α2 = 0.01 × D to 0.04 × D, where D is the same as described above).
[2] At a distance above the bottom surface (0D) of the reactor, a rotary atomizer as a molecular oxygen blowing means is placed in a specific range position R-1 (where R-1 = 0.3 × D to 0.8 ×). D and D are the same as described above).
[3] At a distance above the bottom surface (0D) of the oxidation reactor, the stirring blades are moved to specific range positions C-1 and C-2 (where C-1 = 1.4 × D to 3.0 × D, C-2 = 2.7 × D to 3.3 × D, where D is the same as described above).
[4] Air is introduced from the specific range position N-1 to the lower part of the rotor atomizer at a distance above the bottom surface (0D) of the oxidation reactor, and the raw material polymethylbenzaldehyde is introduced from the specific range position N-2. The catalyst and the solvent are introduced from the specific range position N-3. (However, N-1 = 0.3 × D to 0.8 × D, N-2 = 1.4 × D to 3.0 × D, N-3 = 2.7 × D to 3.3 × D , D is the same as described above.) The produced oxidation reaction liquid is extracted from the bottom (0D) of the oxidation reactor.
[5] A partition disk is provided to enable fractional oxidation and moderate extrusion flow oxidation reaction, and to allow highly dispersed molecular oxygen to be blown using a rotary atomizer, air introduction position, raw material introduction position, It features a method for producing high yield aromatic polycarboxylic acids by optimizing the catalyst and solvent introduction positions.

  For example, FIG. 4 shows an example of an oxidation reactor according to the present invention, which is a vertical reactor, and has a partition disk (1) for partitioning the space into three parts, and a catalyst in the first space part from the top. And the solvent charging port (5), and the raw material charging port (6) is attached to the second space from the top in the horizontal direction. In addition, the bottom of the reactor has an air blowing port (7) attached near the lower surface of the rotary atomizer (3), which will be described later, and a reaction liquid outlet (8) attached to the bottom surface. ing. A heating jacket (18) is attached to the outside of the reactor. In addition, the reactor has a stirring shaft (4) in the vertical direction at the center when viewed from above, and a rotary atomizer (3) at the bottom of the stirring shaft. It has wings (2).

  The stirring blade may be either a shearing type or a discharge type. Specifically, any of turbine blades (FIG. 5), inclined paddle blades (FIG. 6), and paddle blades (FIG. 7) can be used, but it is preferable to use turbine blades. There are no particular restrictions on the number of blades.

  The rotary atomizer is as disclosed in Japanese Patent Publication No. 43-13121. In other words, a rotor that can rotate a solid, hollow or bottomed cylindrical body that does not have a gas delivery port on the side wall is installed at the bottom of the reactor, and a gas delivery port is installed near the lower part of the rotor. It is a contact device that captures the gas sent in the vicinity of the rotor, refines it by the rotational shear force, and releases it into the liquid.

The side, top and exploded views of the rotor in the present invention are shown in FIGS.
For example, FIG. 8 shows a combination of air collecting and blowing pieces (FIG. 11) that collect air that has entered from the lower part and that is discharged horizontally, and an air diffusion cylinder (FIG. 10) that sprays the air. More specifically, the air collecting and blowing piece looks like a circular truncated cone with a cylindrical shape in the vertical direction on the upper surface, for example, a shape like an Erlenmeyer flask. The inside is a hollow portion, and the insertion port of the stirring shaft (20) in the hollow portion of the cylindrical portion (FIG. 11) matches the diameter of the stirring shaft. Further, in the vicinity of the center in the vertical direction of the piece, there is a blowout port (15) (FIG. 11) through which air escapes. Therefore, the air that has entered from (16) of the lower air collection port (FIG. 11) escapes in the horizontal direction via the cavity, and does not escape to the upper part in the vertical direction. The extracted air is sent to the air diffusion cylinder, and the upper surface of the air diffusion cylinder has an upper plate (11) having a width from the circumferential direction to the center (FIG. 8). Therefore, it does not come off in the vertical direction immediately, and it comes off in the form of a spray through the slit by the centrifugal force of rotation.

  It is preferable that the raw material charging port is opened at a position separated by a distance d (mm) (where d = 1.2 × D to 2.5 × D) from the bottom surface of the reactor. If it opens to the bottom of the reactor, that is, the portion near the gas inlet located under the reactor, the oxidation of the formyl group does not proceed well, and problems such as the formation of by-products of high boiling point occur. In addition, when the opening position is at the same height as the liquid level, that is, near the gas-liquid interface, if it is in the gas phase, the oxidant air and the raw material may be in direct contact with each other. Oxidation does not proceed selectively.

  There are no particular restrictions on the number or shape of the partition disks as long as they are two or more, but it is preferable that the step spacing does not exceed twice the diameter of the tower reactor. The installation position is a distance β (mm) from the bottom of the reactor to the upper side (where β is the height of the reaction liquid level (9) at the time of standing of the total liquid volume including the raw material polymethylbenzaldehyde, catalyst and solvent) It is preferable not to exceed. Also, the shape is not particularly limited, but it is preferably a donut-shaped disk that is a space between the end surface of the stirring shaft and the inner surface of the reactor. It is preferable to provide a lateral distance (clearance) of 0.01 × D to 0.04 × D (mm) between 01 × D and 0.04 × D (mm) and the inner surface of the reactor.

  However, when polymethylbenzaldehyde supplied from the raw material supply port located above the reactor is oxidized by the air exiting from the gas inlet located below the reactor, the air concentration can be increased by providing two or more partition plates. For the purpose of gradually oxidizing by providing a gradient to selectively oxidize the formyl group, the number and shape are not particularly limited by the specifications described above.

In the present invention, an aromatic polycarboxylic acid having an industrially sufficient yield can be produced.
For example, when 2,4-dimethylbenzaldehyde is continuously liquid-phase air-oxidized with an aqueous solvent, a fractional oxidation-type reaction with a partition disk and a conventional fully-mixed oxidation without an air inlet as a rotary atomizer When the reactor is used, the yield of the high boiling point compound is about 10%. However, a partition disk is provided, a fractionation type oxidation reaction, a rotary atomizer is provided as an air feeding means, molecular oxygen is blown, and the raw material supply port is located at a distance d (mm) upward from the bottom surface of the reactor (d = By using a column reactor opened at a position separated by 1.2 × D to 2.5 × D (mm)), the yield of the high boiling point compound is reduced to 5% or less.

When polymethylbenzaldehyde is used as a raw material, a fractionation oxidation type having three compartments and an extrusion type oxidation reactor in which a catalyst and a solvent are introduced from the upper part of the reactor and a reaction liquid is extracted from the lower part of the reactor. As a result, the formyl group of the raw material is optimally oxidized and the selective reaction to the target product is optimally progressed to reduce the production of high-boiling substances and intermediates. Industrial production of high-quality, high-purity aromatic polycarboxylic acids with few products is achieved.

  Polymethylbenzaldehyde, the raw material for oxidation, includes 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, 2,4-dimethylbenzaldehyde, 2,5-dimethylbenzaldehyde, 2,4,5-trimethylbenzaldehyde, 2,4, Examples include 6-trimethylbenzaldehyde.

  The metal used for the catalyst contains at least one of cobalt, manganese, and cerium, and each can be used alone or in a mixture. These metals may be used in any form, and may be an organic salt or an inorganic salt, but are preferably present as ions in an aqueous solvent, more preferably a bromide salt, specifically, Cobalt bromide, manganese bromide, cerium bromide. The bromine used for the catalyst is preferably hydrobromic acid in addition to the bromine from the bromide salt.

  The amount of metal in the catalyst is 0.05 to 1% by weight, more preferably 0.1 to 0.5% by weight, based on the aqueous solvent. Bromine is used in an amount of 1 to 5% by weight based on the aqueous solvent, but more preferably 1.5 to 4% by weight.

  The oxidation method is preferably a continuous method, but a multistage continuous method is preferable, and a two-stage continuous method is more preferable. In that case, bromine addition is divided into two stages, and the bromine amount added in the second stage is preferably 5 to 50% by weight of the total bromine amount. By the additional supply of bromide ions within this range, the oxidation reaction rate is improved, and the organic bromine compound in the system is decomposed and reduced, thereby reducing the amount of oxidized intermediate produced. In the first stage, it is preferable to use the reactor shown in FIG. By using the reactor of FIG. 2 in the first stage, oxidation of polymethylbenzaldehyde to polymethylbenzoic acid proceeds selectively, and an aromatic polycarboxylic acid is obtained in high yield.

  The water used for the solvent is not particularly limited as long as it is pure water such as distilled water, ion-exchanged water, or membrane-filtered water, but more preferably water obtained by a pure water production apparatus with a polisher. The weight is preferably used in a range of 1 to 8 times by weight with respect to the weight of the raw material polymethylbenzaldehyde, and in a range of 1 to 6 times by weight with respect to polydimethylbenzaldehyde. Is more preferable.

  In the case of a two-stage oxidation reaction, the reaction temperature of each of the first stage and the second stage is 200 to 250 ° C, preferably 210 to 230 ° C.

  When an aromatic polycarboxylic acid is produced by air oxidation in a liquid phase using bromide ions and heavy metal (for example, manganese) ions in a water solvent as a raw material using polymethylbenzaldehyde as a raw material, In the stage, the formyl group is oxidized to produce polymethylbenzoic acid. However, in this case, unless the reaction conditions are appropriately controlled, oxygen in the air is not properly absorbed, and oxidation to polycarboxylic acid does not proceed selectively, such as formation of a high boiling point compound. That is, in order to produce an aromatic polycarboxylic acid using polymethylbenzaldehyde as a raw material, an initial oxidation reaction stage for producing polymethylbenzoic acid is important.

  The present invention is an invention of a fractional oxidation type oxidation reactor having three compartments as a means for selectively advancing the oxidation of formyl groups at an early stage. In addition, the present invention uses the oxidation reactor, uses a catalyst composed of at least one of cobalt, manganese and cerium and bromine, molecular oxygen, and polymethylbenzaldehyde as an aromatic polycarboxylic acid using water as a solvent. It is an invention of a manufacturing method. Specifically, a fractional oxidation reaction using a partition disk, an extrusion oxidation reaction in which a catalyst and a solvent are introduced from the upper part of the reactor, and a reaction solution is drawn out from the lower part of the reactor, a rotary atomizer as a means for blowing molecular oxygen And a position, a raw material supply port opened at a specific position, and a reactor provided with a catalyst and solvent supply port, which is an invention of an oxidation reactor for continuous liquid phase air oxidation.

  Next, the present invention will be described specifically by way of examples. In addition, this invention is not restrict | limited by these Examples. In Examples and Comparative Examples, the three types of reactors described below were used, and the reaction products were analyzed using a gas chromatography apparatus (GC apparatus) under the following conditions.

Reactor used for reaction <Reactor A (FIG. 12)>
Zirconium pressure-resistant cylindrical container having an inner diameter (D) of 80 mm and a height (H) of 450 mm, with a clearance of 2 mm on the stirring shaft side and side surface side at positions 98 mm and 196 mm above the bottom surface of the reactor. A partition disk (a donut-shaped disk having a diameter of 76 mm and a space around the shaft of 16 mm in diameter) is provided, and a central stirring type stirring shaft is provided with an outer diameter of 35 mm and a height of 20 mm at a position 49 mm above the bottom surface of the reactor. A rotary atomizer with a rotor of the above and an air supply nozzle that is open, turbine blades at positions 147 mm and 245 mm from the bottom surface of the reactor, and a raw material supply that is open 147 mm above the bottom surface of the reactor A fractional oxidation reactor comprising a nozzle and a catalyst and solvent supply nozzle that opens at a position of 245 mm above the bottom surface of the reactor.
<Reactor B (FIG. 13)>
A pressure-resistant cylindrical vessel made of zirconium with an inner diameter of 80 mm and a height of 450 mm, a partition disk (diameter of 76 mm with a clearance of 98 mm and 196 mm on the upper side from the bottom surface of the reactor and a clearance of 2 mm on the stirring shaft side and the side surface side, respectively. And a rotary atomizer having a rotor with an outer diameter of 35 mm and a height of 20 mm at a position 49 mm above the bottom surface of the reactor on a central stirring type stirring shaft. Open air supply port, turbine blade at 147 mm from the bottom surface of the reactor, paddle blade at 245 mm, and raw material supply port at 147 mm above the bottom surface of the reactor A fractional oxidation reactor equipped with a catalyst and solvent supply port opened at a position of 245 mm above the bottom surface of the reactor.
<Reactor C (FIG. 14)>
A zirconium pressure-resistant cylindrical vessel with an inner diameter of 80 mm and a height of 450 mm, an air supply nozzle and a turbine blade opened at a position of 49 mm above the bottom surface of the reactor, a turbine blade and a reaction at positions of 147 mm and 245 mm from the bottom surface of the reactor A tower-type fully mixed reactor equipped with a raw material supply port and a catalyst and solvent supply port which are opened upward by 147 mm from the bottom surface of the reactor.

Model for analysis of reaction products: Agilent 6890N (manufactured by Agilent Technologies)
Column used: DB-1 (manufactured by Agilent Technologies)
Analysis conditions: Injection Temp 300 ° C
Detector Temp 300 ° C
Column temperature: 100 ° C., 3 minutes hold → Temperature rise to 280 ° C. at 5 ° C./minute→280° C., hold for 35 minutes Detector: Hydrogen flame ionization detector (FID)
Analysis method: Collect 1 g of the reaction solution in a heat-resistant glass test tube (examine), dilute by adding 3 g of methanol, and add 3 g of triethylamine hydrochloride and 10 ml of trimethyl phosphate. The mixed solution is subjected to methyl esterification treatment by heating at 180 ° C. for 40 minutes. After cooling the treatment liquid to room temperature, 20 ml of chloroform is added to the liquid, and 0.1 g of triphenylmethane, which is an internal standard substance for GC analysis, is added (examined) and dissolved uniformly. 200 ml of water is added to this chloroform solution to perform a liquid-liquid partitioning treatment (twice), and the chloroform layer obtained by standing is analyzed with a GC apparatus.

<Example 1> Production of trimellitic acid by reactor A Contents of reactor A provided with a reflux condenser, a stirrer, a heating device and a raw material inlet, a catalyst liquid inlet, a bottom air inlet, and a reactant outlet Liquid phase air oxidation of 2,4-dimethylbenzaldehyde was performed using a continuous two-stage reactor connected to a 2 L zirconium oxidation reactor.
1422 parts by mass of water obtained by a pure water production apparatus with a polisher, 37.4 parts by mass of a hydrobromic acid aqueous solution (reagent: manufactured by Wako Pure Chemical Industries, Ltd., HBr 47.0-49.0% by mass), MnBr _2. Catalyst solution A was prepared by mixing 30.5 parts by mass of 4H ₂ O (reagent: manufactured by Mitsuwa Pharmaceutical Co., Ltd.) at this ratio (bromide ion concentration 2.3 wt%, manganese ion concentration 0.39 wt%). . Further, 55.7 parts by mass of water and 4.3 parts by mass of a hydrobromic acid aqueous solution (reagent: manufactured by Wako Pure Chemical Industries, Ltd., HBr 47.0-49.0% by mass) were mixed at this ratio, and catalyst solution B Was prepared (bromide ion concentration 3.4 wt%).
1490 g of catalyst solution A was charged into the first-stage reactor, and 1000 g of catalyst solution A was charged into the second-stage reactor. Nitrogen was injected from the gas inlet of each reactor and the pressure was increased to 1 MPa. Moreover, each temperature was raised to 220 ° C. with a heating device, and the temperature was maintained during the reaction.
Subsequently, 2,4-dimethylbenzaldehyde was separately supplied to the first stage reactor at a rate of 200 g / h, and catalyst solution A (same composition as the reactor charge solution) was separately supplied at a rate of 750 g / h. Simultaneously with the supply of 2,4-dimethylbenzaldehyde, the rotor of the rotary atomizer was rotated to start air feeding from the bottom gas inlet, and the flow rate was controlled to keep the oxygen in the exhaust gas from the reactor at 2.5%. . Next, while maintaining the liquid level in the first stage reactor constant, liquid transfer from the first stage reactor to the second stage reactor was started, and at the same time, 60 g / h of catalyst liquid B was fed into the second stage reactor. The gas was supplied at a rate, and air flow was started from the gas inlet, and the flow rate was controlled so as to keep the oxygen concentration in the exhaust gas from the reactor at 4.5% by volume. The reaction product was extracted from the second stage reactor so that the liquid level in the second stage reactor was kept constant. During this time, the pressure in the reactor was maintained at 3.2 MPa for the first stage and 2.9 MPa for the second stage. The amount of the aqueous solvent was 3.9 times by weight with respect to 2,4-dimethylbenzaldehyde, and the supply amount of bromide ions to the second stage was 10.5% of the total supply amount of bromide ions. After the composition in the reactor became steady, the obtained reaction product solution was methyl esterified, and then GC analysis was performed. As a result, the yield of trimellitic acid in terms of molar ratio was 91.6%, and the yield of the high boiling point compound was 4.8%. The results are shown in Table 1.

<Example 2> Production of pyromellitic acid by reactor A Contents of reactor A provided with a reflux condenser, a stirrer, a heating device and a raw material inlet, a catalyst liquid inlet, a bottom air inlet, and a reactant outlet Liquid phase air oxidation of 2,4,5-trimethylbenzaldehyde was carried out using a continuous two-stage reactor connected with a 2 liter zirconium oxidation reactor.
1433 parts by mass of water obtained by a pure water production apparatus with a polisher, hydrobromic acid aqueous solution (reagent: Wako Pure Chemical Industries, Ltd., HBr 47.0-49.0% by mass) 32.7 parts by mass, MnBr _2. 34.5 parts by mass of 4H ₂ O (reagent: manufactured by Mitsuwa Pharmaceutical Co., Ltd.) and 50% by mass FeBr ₃ aqueous solution (reagent: manufactured by Mitsuwa Chemicals Co., Ltd., 9.4% by mass as Fe content) 0.21 parts by mass Were mixed at this ratio to prepare catalyst solution A (bromide ion concentration 2.3 wt%, manganese ion concentration 0.44 wt%, iron ion concentration 13 ppm). Further, 55.7 parts by mass of water and 4.3 parts by mass of a hydrobromic acid aqueous solution (reagent: manufactured by Wako Pure Chemical Industries, Ltd., HBr 47.0-49.0% by mass) were mixed at this ratio, and catalyst solution B Was prepared (bromide ion concentration 3.4 wt%).
The first-stage reactor was charged with 1500 g of catalyst solution A, and the second-stage reactor was charged with 1000 g of catalyst liquid A. Nitrogen was injected from the gas inlet of each reactor and the pressure was increased to 1 MPa. Moreover, each temperature was raised to 220 ° C. with a heating device, and the temperature was maintained during the reaction.
Then, Example 1 was carried out except that 2,4,5-trimethylbenzaldehyde was separately supplied to the first stage reactor at a rate of 145 g / h and catalyst solution A (same composition as the reactor charged solution) was separately supplied at a rate of 800 g / h. The reaction was carried out in the same manner as in 1. The amount of the aqueous solvent was 5.8 times by weight with respect to 2,4,5-trimethylbenzaldehyde, and the supply amount of bromide ions to the second stage was 10.0% of the total supply amount of bromide ions. After the composition in the reactor became steady, the obtained reaction product solution was methyl esterified, and then GC analysis was performed. As a result, the yield of pyromellitic acid by molar ratio was 81.8%, and the yield of the high boiling point compound was 4.2%. The results are shown in Table 2.

<Example 3> Production of trimellitic acid using reactor B Except that reactor B was used instead of reactor A, the reaction was carried out in the same manner as in Example 1, and the reaction product was subjected to GC analysis. As a result, trimellitic acid was obtained in a molar ratio of 90.2%, and a high boiling point compound was obtained in a yield of 5.9%. The results are shown in Table 1.

<Example 4> Production of pyromellitic acid using reactor B Except that reactor B was used instead of reactor A, the reaction was carried out in the same manner as in Example 2, and the reaction product was subjected to GC analysis. As a result, pyromellitic acid was obtained in a molar ratio of 81.2%, and a high boiling point compound was obtained in a yield of 4.8%. The results are shown in Table 2.

<Comparative Example 1> Production of trimellitic acid using reactor C Except that the reactor C was used instead of the reactor A, the reaction was carried out in the same manner as in Example 1, and the reaction product was subjected to GC analysis. As a result, the trimellitic acid was obtained in a molar ratio of 85.3%, and the high boiling point compound was obtained in a yield of 9.6%. The results are shown in Table 1.

<Comparative example 2> Production of pyromellitic acid using reactor C Except that the reactor C was used instead of the reactor A, the reaction was carried out in the same manner as in Example 2, and the reaction product was subjected to GC analysis. As a result, pyromellitic acid was obtained in a molar ratio of 74.1%, and a high boiling point compound was obtained in a yield of 9.7%. The results are shown in Table 2.

  It can be seen that any of Comparative Examples 1 and 2 has a lower yield of trimellitic acid and pyromellitic acid than Examples 1 to 4.

  When the polymethylbenzaldehyde of the present invention is used as a raw material, a central stirring type stirring blade, a partition disk for means for dividing the oxidation reaction, a rotary atomizer at the bottom of the reactor as means for blowing molecular oxygen, The raw material supply port opened at a position separated by d (provided that d = 1.2 × D to 2.5 × D) from the bottom to the top and e from the bottom of the reactor (note that e = 2) Aromatic polycarboxylic acid can be obtained in a satisfactory yield without using a fractional reactor equipped with a catalyst opening at a position of 5 × D to 3.7 × D) and a solvent supply port. Thus, the yield of high boiling point compounds increases to about 10%. On the other hand, it can be seen that when the tower-type fractional oxidation reactor of the present invention is used, the yield of aromatic polycarboxylic acid is good and the yield of high-boiling compounds is also low.

Standard dimensions and symbol name of oxidation reactor Structure of tower type oxidation reactor An example of an aromatic polycarboxylic acid oxidation reactor in the present invention An example of an aromatic polycarboxylic acid oxidation reactor in the present invention Turbine blade Inclined paddle wing Paddle wing 1 Rotor side view Top view of FIG. Rotor exploded view (air diffusion cylinder) Rotor exploded view (air collection, blowing piece) Example of reactor structure Example of reactor structure Example of reactor structure

A ... Section (A) (between the reaction liquid level and P-2)
B ... Section (B) (between P-1 and P-2)
C ... Section (C) (between bottom of reactor and P-1)
1 ... Partition disk (bottom is P-1, top is P-2)
2 ... Stirring blade 3 ... Rotary atomizer 4 ... Central stirring type stirring shaft 5 ... Catalyst and solvent charging port 6 ... Raw material charging port 7 ... Air blowing port 8 ... Reaction liquid outlet port 9 ... Reaction liquid level 10 …… Air collection, blowing piece 11 …… Upper plate 12 …… Lower plate 13 …… Air diffusion cylinder 14 …… Slit 15 …… Air ejection port 16 …… Air collection port 17 …… Turbine blade 18 ... Jacket 19 ... Paddle blade 20 ... Rotating slot

Claims (8)

A reactor body;
A jacket (18) is provided around the reactor body, a central stirring type stirring shaft (4) is provided inside the reactor body, and two stirring blades (2) are provided on the stirring shaft (4). ) And a rotary atomizer (3) is connected to the bottom of the stirring shaft (4), and the internal space of the reactor is divided into two compartments (A) by two partition disks (1). ), Compartment (B) and compartment (C), and compartment (A) is provided with catalyst and solvent inlets (5), and compartment (B) is charged with raw materials (6). A reactor for liquid phase oxidation, wherein the compartment (C) is provided with a molecular oxygen charging port (7) and a reaction liquid outlet port (8).   The vertical distance between the lower surface of the partition disk (1) and the bottom surface of the reactor is 0.9 × D to 1.5 × D (mm) (D is the inner diameter of the reactor (mm)), the partition circle The reaction according to claim 1, wherein the longitudinal distance between the lower surface of the plate (1) and the bottom surface of the oxidation reactor is 2.1 x D to 2.8 x D (mm) (D is the same as above). vessel.   The lateral distance (clearance) between the end face of the stirring shaft (4) and the end face of the two partition disks (1) is 0.01 × D to 0.04 × D (mm) The reactor according to claim 1.   The lateral distance (clearance) between the end face of the inner surface of the reactor and the end faces of the two partition disks (1) is 0.01 × D to 0.04 × D (mm) (D is the above) The reactor according to claim 1, which is the same.   The reactor according to claim 1, wherein the rotary atomizer (3) is rotated by being connected to a central stirring type stirring shaft (4) and is located above a molecular oxygen charging port (7). .   The reactor according to claim 1, wherein the jacket (18) functions as a means for warming or keeping warm of the reactor.   In the manufacturing method which manufactures aromatic polycarboxylic acid by the liquid phase oxidation reaction which uses polymethylbenzaldehyde as a raw material, it is using the reactor for liquid phase oxidation of any one of Claims 1-6. A method for producing an aromatic polycarboxylic acid. The method for producing an aromatic polycarboxylic acid according to claim 7, wherein the aromatic polycarboxylic acid is trimellitic acid or pyromellitic acid.

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