CN112774592B - Micro-interface reaction system and method for hydrofining crude terephthalic acid - Google Patents
Micro-interface reaction system and method for hydrofining crude terephthalic acid Download PDFInfo
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- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 title claims abstract description 186
- 238000006243 chemical reaction Methods 0.000 title claims abstract description 62
- 238000000034 method Methods 0.000 title claims description 14
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 130
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 116
- 239000001257 hydrogen Substances 0.000 claims abstract description 116
- 238000005984 hydrogenation reaction Methods 0.000 claims abstract description 83
- 239000003054 catalyst Substances 0.000 claims abstract description 43
- 238000002425 crystallisation Methods 0.000 claims abstract description 11
- 230000008025 crystallization Effects 0.000 claims abstract description 11
- 230000005587 bubbling Effects 0.000 claims abstract description 9
- 239000007787 solid Substances 0.000 claims abstract description 9
- 239000007789 gas Substances 0.000 claims description 61
- 238000009826 distribution Methods 0.000 claims description 48
- UKVIEHSSVKSQBA-UHFFFAOYSA-N methane;palladium Chemical compound C.[Pd] UKVIEHSSVKSQBA-UHFFFAOYSA-N 0.000 claims description 28
- 238000006555 catalytic reaction Methods 0.000 claims description 4
- 238000001035 drying Methods 0.000 claims description 3
- 238000000926 separation method Methods 0.000 claims description 2
- 238000012546 transfer Methods 0.000 abstract description 14
- 239000012295 chemical reaction liquid Substances 0.000 abstract description 4
- 238000010574 gas phase reaction Methods 0.000 abstract 1
- 239000007788 liquid Substances 0.000 description 18
- LPNBBFKOUUSUDB-UHFFFAOYSA-N p-toluic acid Chemical compound CC1=CC=C(C(O)=O)C=C1 LPNBBFKOUUSUDB-UHFFFAOYSA-N 0.000 description 16
- 230000000694 effects Effects 0.000 description 14
- 239000012071 phase Substances 0.000 description 14
- 239000007791 liquid phase Substances 0.000 description 13
- GOUHYARYYWKXHS-UHFFFAOYSA-N 4-formylbenzoic acid Chemical compound OC(=O)C1=CC=C(C=O)C=C1 GOUHYARYYWKXHS-UHFFFAOYSA-N 0.000 description 12
- DYNFCHNNOHNJFG-UHFFFAOYSA-N 2-formylbenzoic acid Chemical compound OC(=O)C1=CC=CC=C1C=O DYNFCHNNOHNJFG-UHFFFAOYSA-N 0.000 description 9
- 239000000047 product Substances 0.000 description 8
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- 238000009792 diffusion process Methods 0.000 description 2
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- 238000005728 strengthening Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000009903 catalytic hydrogenation reaction Methods 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/0093—Microreactors, e.g. miniaturised or microfabricated reactors
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/0053—Details of the reactor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/001—Controlling catalytic processes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
- B01J8/0242—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid flow within the bed being predominantly vertical
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/487—Separation; Purification; Stabilisation; Use of additives by treatment giving rise to chemical modification
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
Abstract
The micro-interface reaction system for the hydrofining of the crude terephthalic acid is characterized by comprising a hydrogenation reactor, wherein a hydrogen micro-interface generator for dispersing broken hydrogen is arranged in the hydrogenation reactor; the hydrogenation reactor is provided with a bubbling tower reactor in parallel connection, and the bubbling tower reactor is connected with an external micro-interface unit; and enabling the product after the reaction of the hydrogenation reactor and the bubble column reactor to sequentially enter a crystallization tower, a centrifugal separator and a dryer in parallel, and finally forming solid refined terephthalic acid to enter a collecting tank. The reaction system of the invention greatly improves the mass transfer rate and the macroscopic hydrogenation rate of the gas phase reaction liquid, thereby reducing the original reaction pressure, reaction temperature and catalyst usage amount and improving the reaction efficiency.
Description
Technical Field
The invention relates to the field of refining of crude terephthalic acid, in particular to a micro-interface reaction system and a micro-interface reaction method for hydrofining of crude terephthalic acid.
Background
The production process of Purified Terephthalic Acid (PTA) is a mainstream production process of terephthalic acid, and generally includes an oxidation process and a hydrotreating process, and the production process thereof is as follows: raw terephthalic acid (CTA) obtained by an oxidation process of raw paraxylene is conveyed to a hydrogenation reactor through a raw material preparation unit, and is distributed through a distribution header pipe and is fully contacted with compressed hydrogen conveyed to the hydrogenation reactor in a space above a liquid layer in the hydrogenation reactor, reaction liquid flows through a reaction liquid layer and a catalyst bed after reaching dissolution balance, hydrogenation reaction is carried out on the catalyst bed, the catalyst bed is generally formed by stacking palladium-carbon catalysts, the raw terephthalic acid (mainly comprising Terephthalic Acid (TA), P-carboxybenzaldehyde (4-CBA) and P-methylbenzoic acid (P-T acid), and the main impurities of P-carboxybenzaldehyde (4-CBA) are subjected to hydrogenation reaction to generate P-methylbenzoic acid (P-T acid). The effect of hydrogenation is measured by taking the content of P-carboxybenzaldehyde (4-CBA) in a reaction product after hydrogenation treatment under the same process condition as an index, namely, the lower content of P-carboxybenzaldehyde (4-CBA) in the reaction product indicates that the effect of hydrogenation treatment is better.
Through the research on the reaction process, the internal and external diffusion speeds of the gas phase and the liquid phase main body in the reactant (4-CBA, hydrogen and p-methylbenzoic acid) on the surface of the catalyst are the control steps of the hydrogenation reaction process of the carboxybenzaldehyde (4-CBA), and how to increase the gas-liquid phase interfacial area and improve or strengthen the internal and external diffusion of the gas phase and the liquid phase main body in the reactant on the surface of the catalyst is very important for improving the hydrotreating effect.
The current crude terephthalic acid hydrogenation process is mainly a trickle bed hydrogenation process. The conventional hydrogenation process has the following general problems:
(1) The gas-liquid phase interface area is small, and the mass transfer rate is low. And the hydrogen is unevenly distributed in the solution, the hydrogenation effect is poor, and the catalyst loss is large.
(2) The trickle bed hydrogenation process has higher reaction pressure (about 8 MPa), high investment cost and operation cost of the device and reduced safety.
In view of this, the present invention has been made.
Disclosure of Invention
The first aim of the invention is to provide a micro-interface reaction system for the hydrogenation refining of crude terephthalic acid, which is based on a micro-interface reaction strengthening technology, takes a crude terephthalic acid solvent as a continuous phase, efficiently breaks hydrogen into micron-sized bubbles through a micro-interface generator, disperses the micron-sized bubbles into a solution to form a micro-interface system, improves the gas-liquid phase interfacial area in a hydrogenation reactor by tens of times, greatly improves the mass transfer rate and the macroscopic hydrogenation rate of gas phase to reaction liquid, further reduces the original reaction pressure, reaction temperature and catalyst usage amount, and improves the reaction efficiency.
The second aim of the invention is to provide a reaction method for hydrofining terephthalic acid by adopting the reaction system, wherein the obtained refined terephthalic acid has high purity, low impurity content and wide application, improves the application range of the refined terephthalic acid, and is worthy of wide popularization and application.
In order to achieve the above object of the present invention, the following technical solutions are specifically adopted:
the invention provides a micro-interface reaction system for hydrofining crude terephthalic acid, which comprises the following components: the hydrogenation reactor is internally provided with a hydrogen micro-interface generator for dispersing broken hydrogen;
the side wall of the hydrogenation reactor is communicated with a crude terephthalic acid pipeline and a hydrogen gas inlet pipeline, and the hydrogen gas inlet pipeline passes through the side wall of the hydrogenation reactor and is introduced into the hydrogen micro-interface generator;
the hydrogenation reactor is provided with a bubbling tower reactor in parallel, the bubbling tower reactor is connected with an external micro-interface unit, and the crude terephthalic acid pipeline and the hydrogen gas inlet pipeline are led into the external micro-interface unit;
and enabling the product after the reaction of the hydrogenation reactor and the bubble column reactor to sequentially enter a crystallization tower, a centrifugal separator and a dryer in parallel, and finally forming solid refined terephthalic acid to enter a collecting tank.
The hydrofining terephthalic acid reaction in the prior art has the following defects of small gas-liquid phase interfacial area and low mass transfer rate. And the hydrogen is unevenly distributed in the solution, the hydrogenation effect is poor, and the catalyst loss is large. Secondly, the existing hydrogenation process has higher reaction pressure, high investment cost and operation cost of the device and reduced safety. According to the invention, the hydrogen micro-interface generator is arranged in the hydrogenation reactor, so that the entering hydrogen is crushed and dispersed into hydrogen micro-bubbles, thereby improving the mass transfer effect, enhancing the reaction efficiency, and reducing the pressure, the temperature and the catalyst consumption during the reaction. The invention also discloses an external micro-interface unit arranged outside the bubble tower reactor, which breaks and disperses the entering hydrogen into hydrogen micro-bubbles, and the hydrogen micro-bubbles are mixed with the crude terephthalic acid in advance to enter the bubble tower reactor, so that the mass transfer effect is improved, the reaction efficiency is enhanced, and the pressure, the temperature and the usage amount of the catalyst in the reaction are reduced. And (3) enabling products generated by the reaction of the hydrogenation reactor and the bubble column reactor to enter a crystallization tower, removing the p-methylbenzoic acid, then entering a centrifugal separator to obtain solid refined terephthalic acid, then entering a dryer to remove excessive moisture, and finally forming the solid refined terephthalic acid, and entering a collection tank for packaging and storage.
Preferably, the hydrogen micro-interface generator is arranged at the bottom of the hydrogenation reactor. The hydrogen micro-interface generator is arranged at the bottom of the hydrogenation reactor because the density of the hydrogen is small and the rising speed in the liquid is high, and the hydrogen micro-interface generator is arranged at the bottom of the hydrogenation reactor, so that the rising distance of the hydrogen can be prolonged, and the hydrogen can be more fully hydrogenated with the crude terephthalic acid. And the hydrogen micro-interface generator is arranged at the bottommost part, so that the entering raw material liquid phase and hydrogen are in contact more fully, and after the hydrogen micro-interface generator breaks up the dispersed gas, the part of the out micro-bubbles can stay on the surface of the liquid and is still, so that a sufficient stay space is provided for the part of the stay micro-bubbles, and the mass transfer effect between the gas phase and the liquid phase is more effectively improved.
Preferably, a gas distribution pipeline is arranged in the hydrogenation reactor, gas distribution holes are uniformly distributed on the gas distribution pipeline, the gas distribution pipeline is vertically arranged on the upper surface of the hydrogen micro-interface generator and is communicated with the hydrogen micro-interface generator, and a gas outlet of the hydrogen micro-interface generator is connected with the gas distribution pipeline to uniformly disperse hydrogen micro-bubbles which are crushed and dispersed by the hydrogen micro-interface generator into the hydrogenation reactor. The gas distribution pipeline is uniformly distributed with gas distribution holes, the gas distribution pipeline is vertically arranged on the upper surface of the hydrogen micro-interface generator and is communicated with the hydrogen micro-interface generator, the gas outlet of the hydrogen micro-interface generator is connected with the gas distribution pipeline, and hydrogen micro-bubbles from the hydrogen micro-interface generator are uniformly dispersed into the hydrogenation reactor by being discharged from the gas distribution holes through the gas distribution pipeline which is vertically arranged.
Preferably, a palladium-carbon catalyst bed layer is arranged in the hydrogenation reactor, and the palladium-carbon catalyst bed layer is coated on the outer side of the gas distribution pipeline. The palladium-carbon catalyst bed layer is coated on the outer side of the gas distribution pipeline, the crude terephthalic acid enters the palladium-carbon catalyst bed layer, and broken and dispersed microbubbles are uniformly dispersed into the palladium-carbon catalyst bed layer from the gas distribution pipeline to carry out hydrogenation reaction with the crude terephthalic acid, so that the utilization rate of the palladium-carbon catalyst is enhanced, and the reaction efficiency is improved.
In the structure, the gas distribution pipeline and the hydrogen micro-interface generator are used in a combined mode, so that the dispersing and crushing effect of the hydrogen micro-interface generator is improved, the design of the gas distribution pipeline can be understood as an auxiliary micro-interface generator, the gas redispersing and crushing effect can be achieved to a certain extent by utilizing the gas distribution holes on the gas distribution pipeline, bubbles from the hydrogen micro-interface generator are disordered, and the bubbles can be distributed towards the set direction by utilizing the gas distribution effect of the gas distribution pipeline so as to ensure that the bubbles penetrate through the catalyst bed layer and the bed layer from different directions to be fully contacted with raw material liquid. The mode of arranging the palladium-carbon catalyst bed layer on the outer side of the gas distribution pipeline is designed uniquely for improving the catalytic mass transfer effect.
Preferably, the hydrogen micro-interface generator, the gas distribution pipeline and the central axis of the palladium-carbon catalyst bed layer are all arranged on the central axis of the hydrogenation reactor. The hydrogen micro-interface generator, the gas distribution pipeline and the palladium-carbon catalyst bed layer have the same central axis, and because the gas outlet of the hydrogen micro-interface generator is arranged on the central axis of the hydrogen micro-interface generator, the gas distribution pipeline is connected with the gas outlet of the hydrogen micro-interface generator, the gas distribution pipeline is also arranged on the central axis of the hydrogen micro-interface generator, and the palladium-carbon catalyst bed layer is coated on the outer side of the gas distribution pipeline, the central axis of the palladium-carbon catalyst bed layer is the same as that of the hydrogen micro-interface generator. The central axes of the hydrogen micro-interface generator, the gas distribution pipeline and the palladium-carbon catalyst bed layer are arranged on the central axis of the hydrogenation reactor, so that the distances between the hydrogen micro-bubbles coming out of the gas distribution pipeline and the inner wall of the hydrogenation reactor are equal, and the reaction range can be enlarged to the greatest extent.
Preferably, the external micro-interface unit is composed of a plurality of external micro-interface generators, the crude terephthalic acid pipeline is led into the external micro-interface generators at the top of the external micro-interface unit, and the hydrogen gas inlet pipeline is led into the external micro-interface generators at the bottom of the external micro-interface unit.
Preferably, the number of the external micro-interface generators is 3, and a connecting channel is arranged between every two adjacent external micro-interface generators.
Preferably, the external micro-interface generator is sequentially arranged from top to bottom along the vertical direction.
The number of the external micro-interface generators is three and the external micro-interface generators at the bottom of the external micro-interface unit are sequentially arranged from top to bottom along the vertical direction, and the hydrogen inlet pipeline is connected with the external micro-interface generators at the bottom of the external micro-interface unit, so that hydrogen enters the three external micro-interface generators from bottom to top in sequence, which is equivalent to forming a micro-interface system once in each micro-interface generator, so that the gas phase is fully crushed and dispersed in the micro-interface generator on the premise of taking the liquid phase as a medium. The crude terephthalic acid pipeline is connected with the external micro-interface generator at the top of the external micro-interface unit, because the crude terephthalic acid solution is liquid, the crude terephthalic acid solution can flow from the top of the external micro-interface unit to the bottom of the external micro-interface unit under the influence of gravity, and therefore hydrogen is driven to circulate in the micro-interface unit. The connecting channels are arranged between the external micro-interface generators, so that crude terephthalic acid solution and hydrogen between the three external micro-interface generators can be communicated. And a pumping pump is arranged outside the external micro-interface unit and used for conveying the crude terephthalic acid solution and hydrogen microbubbles in the external micro-interface unit to the bubble column reactor. The external micro-interface unit has the advantages that the hydrogen is crushed and dispersed in advance before the reaction and is mixed with the crude terephthalic acid solution, so that the phase boundary mass transfer area between the hydrogen and the crude terephthalic acid solution is increased, and the reaction efficiency is improved.
Those skilled in the art will appreciate that the micro-interface generator used in the present invention is embodied in prior patents by the present inventors, such as patent application nos. CN201610641119.6, CN201610641251.7, CN201710766435.0, CN106187660, CN105903425A, CN109437390A, CN205833127U and CN 207581700U. The specific product structure and working principle of the micro bubble generator (i.e. the micro interface generator) are described in detail in the prior patent CN201610641119.6, and the application document describes that the micro bubble generator comprises a body and a secondary crushing member, the body is provided with a cavity, an inlet communicated with the cavity is arranged on the body, the opposite first end and the second end of the cavity are both open, wherein the cross-sectional area of the cavity is reduced from the middle part of the cavity to the first end and the second end of the cavity; the secondary crushing member is arranged at least one of the first end and the second end of the cavity, a part of the secondary crushing member is arranged in the cavity, and an annular channel is formed between the secondary crushing member and the through holes with two open ends of the cavity. The micro bubble generator also comprises an air inlet pipe and a liquid inlet pipe. The specific working principle of the structure disclosed in the application document is known as follows: the liquid enters the micro bubble generator tangentially through the liquid inlet pipe, and the gas is rotated and cut at ultrahigh speed to break the gas bubbles into micro bubbles in micron level, so that the mass transfer area between the liquid phase and the gas phase is increased, and the micro bubble generator in the patent belongs to a pneumatic micro interface generator.
In addition, in the prior patent 201610641251.7, it is described that the primary bubble breaker has a circulating liquid inlet, a circulating gas inlet and a gas-liquid mixture outlet, and the secondary bubble breaker communicates the feed inlet with the gas-liquid mixture outlet, which means that the bubble breaker needs to be mixed with gas and liquid, and in addition, as seen in the following figures, the primary bubble breaker mainly uses the circulating liquid as power, so that the primary bubble breaker belongs to a hydraulic micro-interface generator, and the secondary bubble breaker simultaneously introduces the gas-liquid mixture into an elliptical rotating ball for rotation, thereby realizing bubble breaking during rotation, so that the secondary bubble breaker actually belongs to a gas-liquid linkage micro-interface generator. In fact, both the hydraulic type micro-interface generator and the gas-liquid linkage type micro-interface generator belong to a specific form of the micro-interface generator, however, the micro-interface generator adopted by the invention is not limited to the above-mentioned forms, and the specific structure of the bubble breaker described in the prior patent is only one form which can be adopted by the micro-interface generator of the invention.
Furthermore, the prior patent 201710766435.0 states that the principle of the bubble breaker is that the high-speed jet flows are used for achieving the mutual collision of gases, and also states that the bubble breaker can be used for a micro-interface strengthening reactor, and the correlation between the bubble breaker and the micro-interface generator is verified; in addition, in the prior patent CN106187660, there are also related descriptions about specific structures of bubble breakers, specifically, see paragraphs [0031] to [0041] in the specification, and the accompanying drawings, which describe the specific working principle of the bubble breaker S-2 in detail, wherein the top of the bubble breaker is a liquid phase inlet, the side is a gas phase inlet, and the entrainment power is provided by the liquid phase entering from the top, so as to achieve the effect of breaking into ultrafine bubbles.
Since the micro-interface generator was just developed in the early stage of the prior patent application, the micro-interface generator is named as a micro-bubble generator (CN 201610641119.6), a bubble breaker (201710766435.0) and the like in the early stage, and with the continuous technological improvement, the micro-interface generator is named as a micro-interface generator in the later stage, and the micro-interface generator is equivalent to the prior micro-bubble generator, the bubble breaker and the like in the present invention, but the names are different. In summary, the micro-interface generator of the present invention belongs to the prior art.
In addition, the invention also provides a reaction method for hydrofining crude terephthalic acid, which comprises the following steps:
the crude terephthalic acid is mixed with hydrogen under the catalysis of a palladium-carbon catalyst, dispersed and crushed at a micro-interface, then hydrogenation reaction is carried out, and then crystallization, centrifugal separation and drying are carried out to obtain the refined terephthalic acid.
Preferably, the temperature of the hydrogenation reaction is 260-290 ℃, and the pressure of the hydrogenation reaction is 5-8MPa.
Specifically, the reaction method breaks hydrogen into micro-scale microbubbles through a hydrogen micro-interface generator and releases the microbubbles into a hydrogenation reactor so as to increase the phase boundary mass transfer area between the hydrogen and the crude terephthalic acid in the hydrogenation process of the crude terephthalic acid, so that the hydrogen is fully contacted with the crude terephthalic acid solution in the state of the microbubbles. The hydrogen micro-bubbles formed enter a palladium-carbon catalyst bed layer and are subjected to hydrogenation reaction with crude terephthalic acid. The reaction method also comprises the steps of pre-crushing and dispersing the hydrogen into hydrogen microbubbles by arranging an external micro-interface unit, mixing the hydrogen microbubbles with the crude terephthalic acid, and sending the mixture into a bubbling tower reactor, so that the phase boundary mass transfer area of the hydrogen and the crude terephthalic acid is increased, and the reaction efficiency is improved.
The product obtained by the hydrofining reaction of the crude terephthalic acid has good quality and high yield. Greatly reduces the pressure, temperature and the dosage of palladium-carbon catalyst in the hydrogenation reaction of crude terephthalic acid, has high product purity and is equivalent to improving the productivity.
Compared with the prior art, the invention has the beneficial effects that:
(1) According to the micro-interface reaction system for the hydrofining of the crude terephthalic acid, the hydrogen micro-interface generator connected with the hydrogen inlet pipeline is arranged in the hydrogenation reactor, the hydrogen micro-interface generator breaks hydrogen into micro-bubbles with the diameter of more than or equal to 1 mu m and less than 1mm, so that the hydrogen contacts with crude terephthalic acid particles in a micro-bubble state, the phase boundary mass transfer area between the hydrogen and the crude terephthalic acid is increased in the hydrofining reaction process of the crude terephthalic acid, the crude terephthalic acid is hydrofined after being fully mixed, the hydrogen is broken and dispersed into hydrogen micro-bubbles in advance to be mixed with the crude terephthalic acid by virtue of the external micro-interface unit arranged outside the bubbling tower reactor, and the hydrogen is sent into the bubbling tower reactor for hydrogenation catalytic reaction, so that the reaction efficiency is improved.
(2) Compared with the traditional hydrogenation reaction, the whole reaction system of the invention has the advantages of greatly reduced reaction pressure and temperature and improved product purity.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to designate like parts throughout the figures. In the drawings:
FIG. 1 is a schematic diagram of a micro-interface reaction system for hydrofinishing crude terephthalic acid according to an embodiment of the present invention;
wherein:
11-crude terephthalic acid storage tank; 12-a hydrogen gas inlet pipe;
13-a raw material preheater; 14-a hydrogen pressurizer;
15-crude terephthalic acid pipeline; a 20-hydrogenation reactor;
201-hydrogen micro-interface generator; 202-an air distribution pipeline;
2021-air distribution holes; 203-palladium-carbon catalyst bed;
21-a bubble column reactor; 211-an external micro-interface generator;
213-connecting channels; 214-an external micro-interface unit;
215-bubbling column reactor feed inlet; 212-catalyst bed in the bubble column;
30-a crystallization tower; 40-a centrifugal separator;
a 50-dryer; 60-collection tank.
Detailed Description
The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and detailed description, but it will be understood by those skilled in the art that the examples described below are some, but not all, examples of the present invention, and are intended to be illustrative of the present invention only and should not be construed as limiting the scope of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
In order to more clearly illustrate the technical scheme of the invention, the following description is given by way of specific examples.
Examples
Referring to fig. 1, a micro-interface reaction system for hydrofinishing crude terephthalic acid according to an embodiment of the present invention mainly includes a crude terephthalic acid storage tank 11, a hydrogen gas inlet pipe 12, a hydrogenation reactor 20, a bubble column reactor 21, a crystallization column 30, a centrifugal separator 40, a dryer 50, and a collection tank 60. The crude terephthalic acid storage tank 11 is connected with the hydrogenation reactor 20 and the bubble column reactor 21 through a crude terephthalic acid pipeline 15, and a raw material preheater 13 is further arranged on the crude terephthalic acid pipeline 15, so that the crude terephthalic acid can be preheated to the reaction temperature. The hydrogen inlet pipeline 12 is directly connected to the hydrogen micro-interface generator 201 inside the hydrogenation reactor 20 and the external micro-interface generator 211 at the bottom of the external micro-interface unit 214, and the hydrogen inlet pipeline 12 is also provided with a hydrogen pressurizer 14, so that the hydrogen can be pressurized, and the flow velocity of the hydrogen in the liquid is increased.
One side of the parallel reaction is provided with a crude terephthalic acid pipeline 15 which is introduced into a hydrogenation reactor 20 to provide crude terephthalic acid raw materials for the inside of the hydrogenation reactor 20, and a hydrogen gas inlet pipeline 12 is introduced into a hydrogen micro-interface generator 201 to break up and disperse hydrogen into hydrogen micro-bubbles in advance. The hydrogenation reactor 20 is also provided with a gas distribution pipeline 202 and a palladium-carbon catalyst bed 203. The hydrogen micro-interface generator 201 is arranged at the bottom of the hydrogenation reactor 20, because the density of hydrogen is small and the rising speed in the solution is high, the distance from the hydrogen micro-interface generator 201 to the hydrogenation reactor 20 after the hydrogen comes out of the hydrogen micro-interface generator 201 can be prolonged by arranging the hydrogen micro-interface generator 201 at the bottom of the hydrogenation reactor 20, so that the reaction time of hydrogen and crude terephthalic acid is increased, and the reaction efficiency is improved.
The gas outlet of the hydrogen micro-interface generator 201 is upwards connected with a gas distribution pipeline 202, the gas distribution pipeline 202 is vertically arranged on the hydrogen micro-interface generator 201, and gas distribution holes 2021 are uniformly distributed on the gas distribution pipeline 202. So that the hydrogen microbubbles exiting the hydrogen micro-interface generator 201 can be uniformly dispersed into the hydrogenation reactor 20. The outside of the gas distribution pipeline 202 is covered by a palladium-carbon catalyst bed layer 203, hydrogen microbubbles coming out of the gas distribution holes 2021 enter the palladium-carbon catalyst bed layer 203 and are subjected to hydrogenation reaction with crude terephthalic acid under the catalysis of a palladium-carbon catalyst, so that P-carboxybenzaldehyde (4-CBA) is converted into P-methylbenzoic acid (P-T acid).
The hydrogen micro-interface generator 201, the gas distribution pipeline 202 and the palladium-carbon catalyst bed 203 are all arranged on the central axis of the hydrogenation reactor 20. Because the reaction area can be maximized, if the central axes of the hydrogen micro-interface generator 201, the gas distribution pipe 202, and the palladium-carbon catalyst bed 203 are disposed at one side of the hydrogenation reactor 20, the reaction effect at the other side is affected, thereby reducing the reaction efficiency. The hydrogen micro-interface generator 201, the gas distribution pipeline 202 and the central axis of the palladium-carbon catalyst bed 203 are arranged on the central axis of the hydrogenation reactor 20, and the distances from the hydrogen micro-bubbles which are crushed and dispersed in all directions to the inner wall of the hydrogenation reactor 20 are equal, so that the reaction range is more uniform, the utilization rate of the crude terephthalic acid is improved, and the reaction efficiency is enhanced.
On the other hand, the crude terephthalic acid pipeline 15 is led into an external micro-interface generator 211 at the top of the external micro-interface unit 214, the hydrogen gas inlet pipeline 12 is led into the external micro-interface generator 211 at the bottom of the external micro-interface unit 214, the external micro-interface unit 214 is sequentially arranged from top to bottom by 3 external micro-interface generators 211, and the 3 external micro-interface generators 211 are connected through a connecting channel 213. The hydrogen gas inlet pipeline 12 is connected with the external micro-interface generators 211 at the bottom of the external micro-interface unit 214, because hydrogen gas is gas from bottom to top, and enters the three external micro-interface generators 211 in sequence, which is equivalent to forming a micro-interface system once in each micro-interface generator, so that the gas phase is fully crushed and dispersed in the micro-interface generator on the premise of taking the liquid phase as a medium. The crude terephthalic acid pipeline 15 is connected with the external micro-interface generator 211 at the top of the external micro-interface unit 214, because the crude terephthalic acid solution is liquid, and the crude terephthalic acid solution flows from the top of the external micro-interface unit 214 to the bottom of the external micro-interface unit 214 under the influence of gravity, so that the hydrogen is driven to circulate in the micro-interface unit. The external micro-interface generators 211 are provided with connecting channels 213, so that the crude terephthalic acid solution and hydrogen between the three external micro-interface generators 211 can be communicated. The external micro-interface unit 214 is also provided with a pump for delivering the crude terephthalic acid solution and hydrogen gas microbubbles in the external micro-interface unit 214 to the bubble column reactor 21. The provision of the external micro-interface unit 214 has the advantage that the hydrogen is crushed and dispersed in advance and mixed with the crude terephthalic acid solution before the reaction, thereby increasing the phase boundary mass transfer area between the hydrogen and the crude terephthalic acid solution. The mixed hydrogen microbubbles and crude terephthalic acid enter the bubble column reactor 21 through a feed inlet 215 of the bubble column reactor to be subjected to catalytic hydrogenation reaction with palladium-carbon catalyst in a catalyst bed 212 in the bubble column, so that the P-carboxybenzaldehyde (4-CBA) is converted into P-methylbenzoic acid (P-T acid).
The product obtained by the reaction in the hydrogenation reactor 20 and the bubble column reactor 21 is fed in parallel to the crystallization column 30, and because the solubility of P-methylbenzoic acid (P-T acid) in water is far greater than that of terephthalic acid, the terephthalic acid precipitates crystals in the crystallization column 30, and impurities of P-methylbenzoic acid (P-T acid) are removed.
The purified terephthalic acid precipitated from the crystallization tower 30 is fed to a centrifugal separator 40 to be centrifugally separated, thereby obtaining solid purified terephthalic acid. And then the solid refined terephthalic acid is sent to a dryer 50 for drying, excessive moisture is removed, the solid refined terephthalic acid is obtained, and finally the solid terephthalic acid is put into a collection tank 60 for packaging and preservation.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (6)
1. A micro-interface reaction system for hydrofinishing of crude terephthalic acid, comprising: the hydrogenation reactor is internally provided with a hydrogen micro-interface generator for dispersing broken hydrogen;
the side wall of the hydrogenation reactor is communicated with a crude terephthalic acid pipeline and a hydrogen gas inlet pipeline, and the hydrogen gas inlet pipeline passes through the side wall of the hydrogenation reactor and is introduced into the hydrogen micro-interface generator;
the hydrogenation reactor is provided with a bubbling tower reactor in parallel, the bubbling tower reactor is connected with an external micro-interface unit, and the crude terephthalic acid pipeline and the hydrogen gas inlet pipeline are led into the external micro-interface unit;
the product after the reaction of the hydrogenation reactor and the bubble column reactor is connected in parallel and then sequentially enters a crystallization tower, a centrifugal separator and a dryer, and finally solid refined terephthalic acid is formed and enters a collecting tank;
the hydrogen micro-interface generator is arranged at the bottom of the hydrogenation reactor;
the hydrogenation reactor is characterized in that an air distribution pipeline is arranged in the hydrogenation reactor, air distribution holes are uniformly distributed on the air distribution pipeline, the air distribution pipeline is vertically arranged on the upper surface of the hydrogen micro-interface generator and is communicated with the hydrogen micro-interface generator, and an air outlet of the hydrogen micro-interface generator is connected with the air distribution pipeline to uniformly disperse hydrogen micro-bubbles which are crushed and dispersed by the hydrogen micro-interface generator into the hydrogenation reactor;
a palladium-carbon catalyst bed layer is arranged in the hydrogenation reactor, and the palladium-carbon catalyst bed layer is coated on the outer side of the gas distribution pipeline;
the hydrogen micro-interface generator, the gas distribution pipeline and the central axis of the palladium-carbon catalyst bed layer are all arranged on the central axis of the hydrogenation reactor.
2. The reaction system of claim 1, wherein the external micro-interface unit is composed of a plurality of external micro-interface generators, the crude terephthalic acid pipeline is led into the external micro-interface generator at the top of the external micro-interface unit, and the hydrogen gas inlet pipeline is led into the external micro-interface generator at the bottom of the external micro-interface unit.
3. The reaction system of claim 2, wherein the number of the external micro-interface generators is 3, and a connecting channel is arranged between adjacent external micro-interface generators.
4. The reaction system of claim 3, wherein the external micro-interface generator is arranged in sequence from top to bottom in a vertical direction.
5. A reaction method using the reaction system for hydrofinishing of crude terephthalic acid according to any one of claims 1 to 4, comprising the steps of:
the crude terephthalic acid is mixed with hydrogen under the catalysis of a palladium-carbon catalyst, dispersed and crushed at a micro-interface, then hydrogenation reaction is carried out, and then crystallization, centrifugal separation and drying are carried out to obtain the refined terephthalic acid.
6. The reaction method according to claim 5, wherein the temperature of the hydrogenation reaction is 260 to 290 ℃, and the pressure of the hydrogenation reaction is 5 to 8MPa.
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| CN1960960A (en) * | 2004-05-28 | 2007-05-09 | 三菱化学株式会社 | Method for producing high-purity terephthalic acid |
| WO2011004429A1 (en) * | 2009-07-07 | 2011-01-13 | 株式会社日立プラントテクノロジー | Method for refining crude terephthalic acid |
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