WO2021196383A1

WO2021196383A1 - External micro-interface unit enhanced reaction system and process for production of pta from px

Info

Publication number: WO2021196383A1
Application number: PCT/CN2020/092759
Authority: WO
Inventors: 张志炳; 周政; 张锋; 李磊; 孟为民; 王宝荣; 杨高东; 罗华勋; 杨国强; 田洪舟; 曹宇
Original assignee: 南京延长反应技术研究院有限公司
Priority date: 2020-03-31
Filing date: 2020-05-28
Publication date: 2021-10-07
Also published as: CN111569799B; CN111569799A

Abstract

An external micro-interface unit enhanced reaction system and process for production of PTA from PX. The system comprises a reactor, a first micro-interface generator (17), and a second micro-interface generator (18); the reactor comprises a housing (10), a feed port (22), a first baffle plate (13), a second baffle plate (14), and a circulating heat exchange device partially disposed outside the housing (10); a first reaction zone (11) is formed between the inner wall of one side of the housing (10) and the first baffle plate (13), a first overflow zone (15) is formed between the first baffle plate (13) and the second baffle plate (14), and the first overflow zone (15) is communicated with the first reaction zone (11); a second overflow zone (16) is formed between the second baffle plate (14) and the inner wall of the other side of the housing (10), and a second reaction zone (12) is formed at the bottom of the reactor; the first micro-interface generator (17) is separately connected to the feed port (22) and the circulating heat exchange device, the second micro-interface generator (18) is disposed at the bottom of the second reaction zone (12), and both the first micro-interface generator (17) and the second micro-interface generator (18) are used for breaking raw material air into micro-bubbles.

Description

Enhanced reaction system and process of external micro-interface unit for PX production of PTA

Technical field

The present invention relates to the technical field of chemical engineering, in particular to an enhanced reaction system and process of an external micro-interface unit for PX production of PTA.

Background technique

TA (terephthalic acid) is an important chemical raw material. Generally, PX (para-xylene) is used as raw material, acetic acid is used as solvent, and cobalt acetate, manganese acetate and hydrobromic acid (or tetrabromomethane) are used as catalysts. Under certain temperature and pressure, TA (terephthalic acid) is produced by oxidation with oxygen in the air, which mainly includes 4 steps, p-xylene (PX) → p-tolualdehyde (TALD) → p-toluic acid (p-TA)→p-carboxybenzaldehyde (4-CBA)→terephthalic acid (TA), all four steps are irreversible reactions, and the reaction process is very complicated.

In the prior art, the four oxidation reaction steps in the PX oxidation process are all carried out in the same reactor. However, the first two reaction steps need to use acetic acid as the solvent, and high temperature and high pressure are not suitable. The prior art adopts a mixed reaction process. , Without giving different conditions for different reactions, the acetic acid consumption is large, the energy consumption is high, and accompanied by a large number of side reactions, the impurity content is high, and the product quality cannot be guaranteed.

Summary of the invention

In view of this, the present invention proposes an intensified reaction system and process for an external micro-interface unit for PX production of PTA, which aims to solve the problem of large consumption of acetic acid and high energy consumption in the existing PX production of PTA, accompanied by a large number of side reactions. , High impurity content, product quality cannot be guaranteed.

In one aspect, the present invention provides an enhanced reaction system of an external micro-interface unit for PX production of PTA, which includes a reactor, a first micro-interface generator and a second micro-interface generator; wherein,

The reactor includes a shell, a feed port, a first baffle plate, a second baffle plate, and a circulating heat exchange device partially arranged outside the shell. Both sides of the first baffle plate are connected to the On the inner side wall of the reactor, the height of the top end of the first baffle plate is lower than the height of the liquid level of the reactor, and the position of the bottom end of the first baffle plate is higher than the position of the feed inlet; Both sides of the two baffle plates are connected to the inner side wall of the reactor, the top height of the second baffle plate is lower than or equal to the top height of the first baffle plate, and the second baffle plate The position of the bottom end is higher than the position of the feed inlet, and the bottom end of the second baffle plate is closed and connected to the inner side wall of the housing;

A first reaction zone is formed between the inner wall of one side of the housing and the first baffle plate, and a first overflow zone is formed between the first baffle plate and the second baffle plate. An overflow zone is in communication with the first reaction zone, a second overflow zone is formed between the second baffle plate and the inner wall of the other side of the shell, and the bottom of the reactor is the second reaction zone; During the reaction process, the reaction material in the first reaction zone overflows into the first overflow zone, wherein the catalyst particles fall into the first overflow zone under the action of their own gravity, and the catalyst particles are removed from the first overflow zone. The reaction material in the first overflow zone overflows into the second overflow zone.

The first micro-interface generator is respectively connected with the feed port and the circulating heat exchange device, the second micro-interface generator is arranged at the bottom of the second reaction zone, and the first micro-interface generator Both the second micro-interface generator are used to break the raw material air into micro-bubbles.

Further, in the above-mentioned external micro-interface unit strengthening reaction system for PX production of PTA, the first reaction zone is to convert p-xylene into p-tolualdehyde, p-tolualdehyde into p-toluic acid, A reaction zone for converting p-toluic acid into p-carboxybenzaldehyde, and the second reaction zone is a reaction zone for converting p-carboxybenzaldehyde into terephthalic acid.

Further, in the above-mentioned external micro-interface unit intensified reaction system for PX production of PTA, the bottom of the first baffle plate has a bend, and the bend angle is bent in the direction of the second baffle plate to prevent reaction The upward rush of the airflow at the bottom of the device prevents solid particles from falling into the first overflow zone.

Further, in the above-mentioned external micro-interface unit enhanced reaction system for PX production of PTA, the first micro-interface generator and the second micro-interface generator are both pneumatic micro-interface generators.

Further, in the above-mentioned external micro-interface unit enhanced reaction system for PX production of PTA, at least one circulating pump is provided on the circulating heat exchange device.

Further, in the above-mentioned external micro-interface unit intensified reaction system for PX production of PTA, a first anti-wave grid and a second anti-wave grid are arranged inside the reactor, and the first anti-wave grid is arranged The position is lower than the height of the top of the first baffle plate, and the position of the second anti-wave grille is lower than the position of the feed inlet.

Further, in the above-mentioned external micro-interface unit intensified reaction system for PX production of PTA, a filter screen is also arranged above the inside of the reactor to prevent impurities inside the first reaction zone from entering the top of the reactor.

Further, in the above-mentioned external micro-interface unit enhanced reaction system for PX production of PTA, the top of the reactor is provided with a tail gas outlet, and the bottom of the reactor is provided with a product outlet.

On the other hand, the present invention also proposes an enhanced reaction process of an external micro-interface unit for PX production of PTA, which is characterized in that it includes the following steps:

The mixture of p-xylene, acetic acid and catalyst is passed into the first micro-interface generator, and at the same time, the air is broken into micro-bubbles through the first micro-interface generator, and the mixture is fully mixed and emulsified and then enters the first reaction zone for pairing. The reaction of converting xylene into p-tolualdehyde, p-tolualdehyde into p-toluic acid, and p-toluic acid into p-carboxybenzaldehyde, the unreacted air leaves the liquid surface and rises to the reaction Above the device;

With the continuous progress of the above-mentioned reaction in the first reaction zone, the reaction materials in the reaction process pass through the first anti-wave grid, wherein the catalyst particles fall into the first overflow zone under the action of their own gravity to remove the catalyst. After the particles, the reaction material in the first overflow zone overflows into the second overflow zone, and the reaction material in the second overflow zone enters the circulating pipe of the circulating heat exchange device to form a circulating stream, The circulating stream is used to control the temperature during the reaction process;

The p-carboxybenzaldehyde generated in the first reaction zone enters the second reaction zone through the second anti-wave grid. The air is broken into microbubbles from the second micro-interface generator and then enters the second reaction zone. Carboxybenzaldehyde undergoes oxidation reaction to generate terephthalic acid.

Further, in the above-mentioned external micro-interface unit intensified reaction process for PX production of PTA, the temperature of the reactor is 160-190° C., and the pressure is 0.62-2.25 MP.

Compared with the prior art, the present invention has the following beneficial effects:

The enhanced reaction system and process of the external micro-interface unit for PX production by PX provided by the present invention adopts a segmented reaction process, and the inside of the reactor is set as the first reaction zone, the second reaction zone, the first overflow zone and the second reaction zone. The two overflow zones realize different reaction conditions for different reaction stages in the same reactor, solve the problem that the acetic acid solvent cannot withstand high temperature and pressure in the first two reaction steps, and use water as the solvent for the p-TA oxidation reaction. It effectively solves the problems of large consumption of acetic acid and high energy consumption in the prior art, accompanied by a large number of side reactions, high impurity content, and product quality cannot be guaranteed.

Further, the external micro-interface unit for PX production of PTA provided by the present invention strengthens the reaction system and process. By installing a micro-interface generator at the feed port and the bottom of the reactor, the air is broken to break it into microbubbles, and The liquid phase material forms an emulsion, which effectively increases the mass transfer area between the air and the liquid phase material, reduces the thickness of the liquid film, and reduces the mass transfer resistance, thereby effectively reducing energy consumption and improving reaction efficiency.

Further, the external micro-interface unit for PX production of PTA provided by the present invention strengthens the reaction system and process. By setting a circulating heat exchange device, the temperature in the reaction process is effectively controlled during the reaction process, and the inside of the reactor is ensured at the same time. The uniformity of the mixing of the reaction materials ensures that the reactants can fully participate in the reaction, thereby greatly improving the utilization rate of the reactants, and at the same time preventing the occurrence of side reactions caused by local temperature unevenness, to a certain extent Improve the quality of the product.

Description of the drawings

By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only used for the purpose of illustrating the preferred embodiments, and are not considered as a limitation to the present invention. Also, throughout the drawings, the same reference symbols are used to denote the same components. In the attached picture:

FIG. 1 is a schematic structural diagram of an enhanced reaction system of an external micro-interface unit for PX production of PTA provided by an embodiment of the present invention.

In the figure: 10 is the shell, 11 is the first reaction zone, 12 is the second reaction zone, 13 is the first baffle plate, 14 is the second baffle plate, 15 is the first overflow zone, 16 is the second overflow Flow area, 17 is the first micro-interface generator, 18 is the second micro-interface generator, 19 is the first anti-wave grid, 20 is the second anti-wave grid, 21 is the filter screen, and 22 is the feed inlet .

Detailed ways

Hereinafter, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. Although the drawings show exemplary embodiments of the present disclosure, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other if there is no conflict. Hereinafter, the present invention will be described in detail with reference to the drawings and in conjunction with the embodiments.

Referring to FIG. 1, an enhanced reaction system of an external micro-interface unit for PX production of PTA according to an embodiment of the present invention includes: a reactor, a first micro-interface generator 17 and a second micro-interface generator 18; The device includes: a housing 10, a feed port 22, a first baffle plate 13, a second baffle plate 14 and a circulating heat exchange device partially arranged outside the housing 10. The two sides of the first baffle plate 13 are connected On the inner side wall of the reactor, the height of the top end of the first partition plate 13 is lower than the height of the liquid level of the reactor, and the position of the bottom end of the first partition plate 13 is higher than the inlet material 21 Position; the two sides of the second partition plate 14 are connected to the inner side wall of the reactor, and the height of the top end of the second partition plate 14 is lower than or equal to the height of the top end of the first partition plate 13 The position of the bottom end of the second partition plate 14 is higher than the position of the inlet 22, and the bottom end of the second partition plate 14 is closed and connected to the inner side wall of the housing 10;

Between the inner wall of one side of the housing 10 and the first partition plate 13 is the first reaction zone 11, and the first reaction zone 11 is used for converting para-xylene into para-tolualdehyde and para-toluene. A reaction zone where formaldehyde is converted into p-toluic acid and p-toluic acid is converted into p-carboxybenzaldehyde, and a first overflow zone 15 is formed between the first baffle 13 and the second baffle 14 , The first overflow zone 15 is in communication with the first reaction zone 11; between the second partition plate 14 and the other inner wall of the housing 10 is a second overflow zone 16, and the reaction The bottom of the vessel is a second reactor 12, and the second reaction zone 12 is a reaction zone where the p-carboxybenzaldehyde is converted to terephthalic acid. During the reaction, the reaction material in the first reaction zone 11 overflows into the first overflow zone 15, and the reaction material in the first overflow zone 15 after removing solid particles overflows into the second overflow zone. The overflow zone 16; the liquid phase stream in the second overflow zone 16 forms a circulating stream through the circulating pipe on the circulating heat exchange device, and the circulating stream is used to effectively control the reaction process during the reaction process At the same time, it ensures the uniformity of mixing between the reactant streams in the reactor, and ensures that each reactant can fully participate in the reaction, thereby greatly improving the utilization of the reactants, and preventing the occurrence of side reactions caused by uneven local temperature. , Improve the quality of products to a certain extent.

In addition, the top of the reactor is also provided with a tail gas outlet. The tail gas includes acetic acid and water. The tail gas enters the subsequent tail gas processing unit, and the separated acetic acid can be recycled and reused, which saves the cost of the enterprise. The bottom of the reactor is also provided with a product outlet, which is used to take out the reaction product terephthalic acid and unreacted p-xylene PX, solvent, catalyst and by-products, etc., and finally the reaction product enters the subsequent separation and refining section.

It is understandable that in the present invention, a staged reaction process is adopted, and the inside of the reactor is arranged as the first reaction zone, the second reaction zone, the first overflow zone and the second overflow zone, so that the reactor can be used in the same reactor. Different reaction conditions are given for different reaction stages in the internal, which solves the problem that the acetic acid solvent cannot withstand high temperature and pressure in the first two reaction steps, and uses water as the solvent for the p-TA oxidation reaction, which effectively solves the consumption of acetic acid in the prior art Large, high energy consumption, accompanied by a large number of side reactions, high impurity content, and product quality cannot be guaranteed.

In this embodiment, the first micro-interface generator 17 is respectively connected to the feed port 22 and the circulating heat exchange device, the second micro-interface generator 18 is arranged at the bottom of the second reaction zone 12, and the first micro-interface generator 17 Both the second micro-interface generator and the second micro-interface generator 18 are pneumatic micro-interface generators, which are used to break the air into micro-bubbles before entering the inside of the reactor, and form an emulsion with the liquid-phase materials, effectively increasing the air and liquid-phase materials. The mass transfer area between them reduces the thickness of the liquid film and reduces the mass transfer resistance, thereby effectively reducing energy consumption and improving reaction efficiency. The specific structure of the micro-interface generator is embodied in the inventor's previous patents, such as the patent of publication number 106215730A. The core of the micro-interface generator is bubble breakage, which will not be repeated here. Regarding the reaction mechanism and control method of the micro-interface generator, it has been disclosed in the previous patent CN107563051B of the present inventor, which will not be repeated here. It is understandable that in the present invention, the micro-interface generator is arranged in each reaction zone inside the reactor, and the air is broken in each reaction zone to break it into micro-bubbles and form an emulsion with the liquid phase material, which is effective The ground increases the mass transfer area between the air and the liquid phase material, reduces the thickness of the liquid film, and reduces the mass transfer resistance, thereby effectively reducing energy consumption and improving reaction efficiency.

Preferably, at least one circulating pump is provided on the circulating heat exchange device of the reactor, and the number of the circulating pumps is not specifically required, and can be added at the corresponding position as required. The installation of multiple circulating pumps can increase the circulating power, making the heat exchange efficiency higher and the heat exchange more uniform.

In this embodiment, the inside of the reactor is also provided with a first wave-breaking grid 19 and a second wave-breaking grid 20, and the first wave-breaking grid 19 is arranged at a position lower than that of the first baffle 13 The height of the top of the second wave grid 20 is lower than the position of the feed inlet 22, and the first wave grid 19 is used to convert the violent full mixed flow in the upper part of the first reaction zone 11 into a horizontal push After the flow, overflow is performed to prevent solid particles from entering the second overflow zone 16; the second wave grid 20 is used to convert the fully mixed flow in the first reaction zone 11 into a horizontal plug flow and then enter the second reaction zone 12.

In this embodiment, a filter screen 21 is also provided above the inside of the reactor to prevent impurities in the first reaction zone 11 from entering the top of the reactor and affecting subsequent tail gas treatment.

Please refer to Figure 1, the working process of the enhanced reaction system of the external micro-interface unit for PX production of PTA in this embodiment is:

First, the raw material mixture including p-xylene, acetic acid, and catalysts (cobalt acetate, manganese acetate, hydrobromic acid) enter the first micro-interface generator 17, and at the same time, pass air into the first micro-interface generator 17 to break It is mixed with the raw material mixture and emulsified, which effectively increases the contact area between the air and the liquid phase reaction material. The emulsified liquid enters the first reaction zone 11 for the first three steps of reaction, that is, p-xylene is converted into p-xylene. Methylbenzaldehyde and p-tolualdehyde are converted into p-toluic acid, and p-toluic acid is converted into p-carboxybenzaldehyde. The unreacted air leaves the liquid surface and passes through the filter screen 21 and rises to the top of the reactor. ；

With the continuous progress of the above-mentioned reaction in the first reaction zone 11, the reaction materials in the reaction process pass through the first anti-wave grid 19, wherein the solid particles fall into the first overflow zone 15 under the action of their own gravity. , The reaction material in the first overflow zone 15 after removing solid particles overflows into the second overflow zone 16, and the reaction material in the second overflow zone 16 enters the circulation of the circulating heat exchange device A circulating stream is formed in the pipeline, and the circulating stream is used to control the temperature during the reaction process;

The p-carboxybenzaldehyde generated in the first reaction zone 11 enters the second reaction zone 12 through the second anti-wave grill 20 provided at the bottom of the reactor, and the air is broken into microbubbles from the second micro-interface generator 18 and then enters the first In the second reaction zone 12, the oxidation reaction with the p-carboxybenzaldehyde produces terephthalic acid as a product.

Obviously, it can be concluded that the staged reaction process is adopted in the present invention, and the inside of the reactor is arranged as the first reaction zone, the second reaction zone, the first overflow zone and the second overflow zone, so as to achieve the same Different reaction conditions are given to different reaction stages in the reactor, which solves the problem that the acetic acid solvent cannot withstand high temperature and high pressure in the first two reaction steps, and uses water as the solvent for the p-TA oxidation reaction, which effectively solves the problem of acetic acid in the prior art. Large consumption, high energy consumption, accompanied by a large number of side reactions, high impurity content, and product quality cannot be guaranteed.

Furthermore, by setting up a micro-interface generator at the feed port and the bottom of the reactor, the air is broken into micro-bubbles, which form an emulsion with the liquid-phase materials, effectively increasing the gap between the air and the liquid-phase materials. The mass transfer area is reduced, the thickness of the liquid film is reduced, and the mass transfer resistance is reduced, thereby effectively reducing energy consumption and improving reaction efficiency.

Furthermore, by setting up a circulating heat exchange device, the temperature in the reaction process is effectively controlled during the reaction process, while ensuring the uniformity of the mixing of the reaction materials in the reactor, and ensuring that the reactants can fully participate The reaction greatly improves the utilization rate of the reactants, and at the same time prevents the occurrence of side reactions caused by uneven local temperature, and improves the quality of the product to a certain extent.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. In this way, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

An enhanced reaction system of an external micro-interface unit for PX production of PTA, which is characterized by comprising: a reactor, a first micro-interface generator and a second micro-interface generator; wherein,

The reactor includes a shell, a feed port, a first baffle plate, a second baffle plate, and a circulating heat exchange device partially arranged outside the shell. Both sides of the first baffle plate are connected to the On the inner side wall of the reactor, the height of the top end of the first baffle plate is lower than the height of the liquid level of the reactor, and the position of the bottom end of the first baffle plate is higher than the position of the feed inlet; Both sides of the two baffle plates are connected to the inner side wall of the reactor, the top height of the second baffle plate is lower than or equal to the top height of the first baffle plate, and the second baffle plate The position of the bottom end is higher than the position of the feed inlet, and the bottom end of the second baffle plate is closed and connected to the inner side wall of the housing;

A first reaction zone is formed between the inner wall of one side of the housing and the first baffle plate, and a first overflow zone is formed between the first baffle plate and the second baffle plate. An overflow zone is in communication with the first reaction zone; between the second baffle plate and the inner wall of the other side of the shell is a second overflow zone, and the bottom of the reactor is the second reaction zone; During the reaction process, the reaction material in the first reaction zone overflows into the first overflow zone, wherein the solid particles fall into the first overflow zone under the action of their own gravity, after removing the solid particles The reaction material in the first overflow zone overflows into the second overflow zone;

The first micro-interface generator is respectively connected with the feed port and the circulating heat exchange device, the second micro-interface generator is arranged at the bottom of the second reaction zone, and the first micro-interface generator Both the second micro-interface generator are used to break the raw material air into micro-bubbles.
The intensified reaction system of an external micro-interface unit for PX production by PX according to claim 1, wherein the first reaction zone is for converting p-xylene into p-tolualdehyde and p-tolualdehyde into A reaction zone where p-toluic acid and p-toluic acid are converted into p-carboxybenzaldehyde, and the second reaction zone is a reaction zone where the p-carboxybenzaldehyde is converted into terephthalic acid.
The intensified reaction system of the external micro-interface unit for PX production by PX according to claim 1, wherein the bottom of the first baffle plate has a bend, and the bend angle faces the direction of the second baffle plate. Bending to prevent the air flow from the bottom of the reactor from rising to prevent solid particles from falling into the first overflow zone.
The enhanced reaction system of the external micro-interface unit for PX production of PTA according to claim 1, wherein the first micro-interface generator and the second micro-interface generator are both pneumatic micro-interface generators.
The intensified reaction system of the external micro-interface unit for PX production of PTA according to claim 1, wherein at least one circulating pump is provided on the circulating heat exchange device.
The intensified reaction system of the external micro-interface unit for PX production by PX according to any one of claims 1 to 5, characterized in that, the inside of the reactor is provided with a first anti-wave grid and a second anti-wave grid , The position of the first wave grid is lower than the height of the top of the first baffle plate, and the position of the second wave grid is lower than the position of the feed inlet.
The intensified reaction system of an external micro-interface unit for PX production by PX according to any one of claims 1 to 5, characterized in that, a filter screen is also provided above the inside of the reactor to prevent the first The impurities inside the reaction zone enter the top of the reactor.
The enhanced reaction system of an external micro-interface unit for PX production of PTA according to any one of claims 1-5, wherein the top of the reactor is provided with a tail gas outlet, and the bottom of the reactor is provided with a product outlet .
An enhanced reaction process of an external micro-interface unit for PX production of PTA, which is characterized in that it comprises the following steps:

The mixture of p-xylene, acetic acid and catalyst is passed into the first micro-interface generator, and at the same time, the air is broken into micro-bubbles through the first micro-interface generator, and the mixture is fully mixed and emulsified and then enters the first reaction zone for pairing. The reaction of converting xylene into p-tolualdehyde, p-tolualdehyde into p-toluic acid, and p-toluic acid into p-carboxybenzaldehyde, the unreacted air leaves the liquid surface and rises to the reaction Above the device;

With the continuous progress of the above-mentioned reaction in the first reaction zone, the reaction materials in the reaction process pass through the first anti-wave grid, wherein the catalyst particles fall into the first overflow zone under the action of their own gravity to remove the catalyst. After the particles, the reaction material in the first overflow zone overflows into the second overflow zone, and the reaction material in the second overflow zone enters the circulating pipe of the circulating heat exchange device to form a circulating stream, The circulating stream is used to control the temperature during the reaction process;

The p-carboxybenzaldehyde generated in the first reaction zone enters the second reaction zone through the second anti-wave grid. The air is broken into microbubbles from the second micro-interface generator and then enters the second reaction zone. Carboxybenzaldehyde undergoes oxidation reaction to generate terephthalic acid.
The enhanced reaction process of the external micro-interface unit for PX production of PTA according to claim 9, wherein the temperature of the reactor is 160-190°C, and the pressure is 0.62-2.25 MPa.