CN-121972124-A - Polyol gradient collaborative depolymerization-esterification coupling reaction device for PETG chemical recovery

CN121972124ACN 121972124 ACN121972124 ACN 121972124ACN-121972124-A

Abstract

The invention discloses a polyol gradient collaborative depolymerization-esterification coupling reaction device for PETG chemical recovery, which belongs to the technical field of depolymerization-esterification coupling reaction devices and comprises a main reaction kettle, wherein the main reaction kettle is of a vertical cylindrical structure, the top of the main reaction kettle is fixedly connected with a sealing cover, a plurality of feeding ports are connected to the sealing cover, a liquid collecting cavity is connected to the lower part of the main reaction kettle, a return pipe is connected to the bottom of the liquid collecting cavity, a one-way valve is arranged on the return pipe, one side of the main reaction kettle is provided with a multistage alcohol feeding system, the other side of the main reaction kettle is provided with a gradient temperature control jacket assembly, and an in-situ esterification module is arranged on the inner side of the main reaction kettle.

Inventors

ZHANG XINZHONG
DONG YANGANG
JING YONGCHUN
WANG XUEWEI
LUO YE
XUE RUIXIANG
GUO BANGLI
LI HUAXI
WU HAIDONG

Assignees

江苏虹港石化有限公司

Dates

Publication Date: 20260505
Application Date: 20260120

Claims (10)

1. The utility model provides a polyol gradient is depolymerization-esterification coupling reaction device in coordination for PETG chemistry is retrieved, including main reation kettle (1), main reation kettle (1) is vertical cylinder structure, main reation kettle (1) top fixedly connected with sealed lid (2), be connected with a plurality of material throwing mouths (3) on sealed lid (2), main reation kettle (1) below is connected with liquid collecting cavity (4), liquid collecting cavity (4) bottom is connected with back flow (5), be provided with check valve (6) on back flow (5), its characterized in that, main reation kettle (1) one side is provided with multistage alcohol feed system, main reation kettle (1) opposite side is provided with gradient temperature control jacket subassembly, main reation kettle (1) inboard is provided with the normal position esterification module.
2. The device for the gradient collaborative depolymerization-esterification coupling reaction of PETG chemical recovery according to claim 1, wherein the multistage alcohol feeding system comprises a first alcohol storage tank (7), a second alcohol storage tank (8) and a third alcohol storage tank (9) which are arranged on one side of a main reaction kettle (1), feeding components are arranged on the first alcohol storage tank (7), the second alcohol storage tank (8) and the third alcohol storage tank (9), each feeding component comprises a feeding pipe (10) which is respectively connected with the first alcohol storage tank (7), the second alcohol storage tank (8) and the third alcohol storage tank (9), a metering pump (11) is connected to the feeding pipe (10), a feeding port (12) is sleeved on the feeding pipe (10), the feeding port (12) is fixedly connected to the outer wall of the main reaction kettle (1), an L-shaped guide pipe (13) is arranged inside the main reaction kettle (1), the L-shaped guide pipe (13) is welded on the feeding port (12), the outlet direction of the L-shaped guide pipe (13) faces the central axis of the main reaction kettle (1) and is inclined downwards at 30 DEG with the horizontal plane, the feeding port (12) is positioned above the initial liquid level (7) and above the main reaction kettle (1) at the initial position of the first alcohol storage tank (12) and above the initial liquid level (8 cm (15 cm above the main reaction kettle (1), the feed inlet (12) on the third tank (9) is positioned at the position 8cm upwards from the bottom of the main reaction kettle (1).
3. The gradient collaborative depolymerization-esterification coupling reaction device for PETG chemical recovery according to claim 2, wherein the gradient temperature control jacket assembly comprises an upper jacket (14), a middle jacket (15) and a lower jacket (16) which are respectively fixed on the outer wall of the main reaction kettle (1) from top to bottom, the upper jacket (14) covers the area from the top of the main reaction kettle (1) to 10cm above the initial height of the liquid level, the middle jacket (15) covers the area from 10cm above the initial height of the liquid level, the lower jacket (16) covers the area from the bottom of the main reaction kettle (1) to 10cm below the initial height of the liquid level, the inner wall of each jacket is provided with spiral guide ribs, the rib height is 2mm, the screw pitch is 50mm, the heat conducting oil inlet of the upper jacket (14) is positioned at the top, the outlet is positioned at the bottom, the heat conducting oil inlet of the middle jacket (15) is positioned at the middle of the side wall, the outlet is symmetrically positioned at the middle of the other side, the heat conducting oil inlet of the lower jacket (16) is positioned at the bottom, and the outlet is positioned at the top.
4. The polyol gradient collaborative depolymerization-esterification coupling reaction device for PETG chemical recovery according to claim 3, wherein the in-situ esterification module is integrally arranged inside a main reaction kettle (1) and comprises an annular distributor (17) fixed on the inner side of the top of the main reaction kettle (1) and a microporous ceramic membrane component embedded into the bottom wall of the main reaction kettle (1), the annular distributor (17) is of a hollow circular ring structure, the inner diameter is 0.6 times of the inner diameter of the main reaction kettle (1), spray holes (18) with the diameter of 1.2mm are uniformly formed in the bottom of the main reaction kettle, and the number of the spray holes (18) is 24.
5. The polyol gradient collaborative depolymerization-esterification coupling reaction device for PETG chemical recovery according to claim 4, wherein the microporous ceramic membrane component comprises three concentric annular inner ring microporous ceramic membranes (19), an intermediate ring microporous ceramic membrane (20) and an outer ring microporous ceramic membrane (21), the inner ring microporous ceramic membranes (19), the intermediate ring microporous ceramic membranes (20) and the outer ring microporous ceramic membranes (21) are fixedly overlapped from top to bottom, each piece has a thickness of 5mm, the aperture of 0.2 μm, the diameter of the outer ring microporous ceramic membrane (21) is equal to the inner diameter of the main reaction kettle (1), the diameter of the intermediate ring microporous ceramic membrane (20) is 0.7 times the diameter of the outer ring microporous ceramic membrane (20), the diameter of the inner ring microporous ceramic membrane (19) is 0.4 times the diameter of the outer ring microporous ceramic membrane (21), the diameter bottom of the outer ring microporous ceramic membrane (21) is fixedly connected with a stainless steel support ring (22), the stainless steel support ring (22) is fixed on the bottom wall of the main reaction kettle (1), and the height of the stainless steel support ring (22) is 8mm.
6. The polyol gradient collaborative depolymerization-esterification coupling reaction device for PETG chemical recovery according to claim 1, characterized in that a product separation unit is arranged on one side of a main reaction kettle (1), the product separation unit comprises a gas phase condenser (23), a liquid phase settling tank (24) and a vacuum distillation tower (25), a reboiler (31) is connected to the bottom of the vacuum distillation tower (25), the gas phase condenser (23) is connected to the top of the main reaction kettle (1) through a gas phase outlet pipeline, a temperature sensor and a pressure transmitter are arranged in the gas phase outlet pipeline, a liquid phase outlet pipeline (26) is connected to the bottom of the liquid phase settling tank (24), the liquid phase outlet pipeline (26) is connected with a return pipe (5), a three-way switching valve (27) is connected to the liquid phase outlet pipeline (26), one branch of the three-way switching valve (27) is connected with the vacuum distillation tower (25), the vacuum distillation tower (25) is of a packed tower structure, and stainless steel theta ring packing is filled in the vacuum distillation tower (25).
7. The polyol gradient collaborative depolymerization-esterification coupling reaction apparatus for PETG chemical recovery according to claim 1, wherein the conduction oil circulation loops of the upper stage jacket (14), the middle stage jacket (15) and the lower stage jacket (16) are respectively provided with independent flow regulating valves and temperature controllers, and the set temperatures of the upper stage jacket (14), the middle stage jacket (15) and the lower stage jacket (16) are 180 ℃, 210 ℃ and 230 ℃, respectively.
8. The polyol gradient synergistic depolymerization-esterification coupling reaction device for PETG chemical recovery according to claim 5, wherein the spray holes (18) of the annular distributor (17) are staggered along the circumferential direction, the central angle between adjacent spray holes (18) is 15 degrees, and the axes of the spray holes (18) are deflected outwards by 10 degrees from the radial direction of the annular distributor (17).
9. The polyol gradient synergistic depolymerization-esterification coupling reaction device for PETG chemical recovery of claim 5, wherein a gap of 2mm is left between the inner ring microporous ceramic membrane (19), the middle ring microporous ceramic membrane (20) and the outer ring microporous ceramic membrane (21), the gap is filled with zirconia spherical filler with the particle size of 1mm, and the surface of the filler is loaded with tetrabutyl titanate catalyst.
10. The gradient collaborative depolymerization-esterification coupling reaction device for PETG chemical recovery according to claim 6, wherein three layers of partition plates (28) are arranged in the liquid phase sedimentation tank (24), the distance between the upper and lower parts of the partition plates (28) is 20cm, a through hole (29) with the diameter of 5cm is formed in the center of each layer of partition plate (28), and a magnetic stirrer (30) is arranged below the bottommost partition plate (28).

Description

Polyol gradient collaborative depolymerization-esterification coupling reaction device for PETG chemical recovery Technical Field The invention relates to the technical field of depolymerization-esterification coupling reaction devices, in particular to a polyol gradient collaborative depolymerization-esterification coupling reaction device for PETG chemical recovery. Background The gradient synergistic depolymerization-esterification coupling reaction of the PETG chemical recovery is an efficient and controllable closed loop process in the PETG chemical recovery, namely, the ester bond (depolymerization) of the PETG is broken by a plurality of polyols in a staged synergistic mode, a depolymerization product is synchronously converted into an esterification product which can be directly used for repolymerization, so that 'depolymerization-esterification one-step coupling' is realized, the core is gradient polyol control reaction, coupling extraction efficiency and high-valued product, acid is taken as a catalyst, polyol is taken as a reagent, the reaction is realized through heating, and with the development of a polyester material recovery technology, a chemical recovery method is paid attention to the fact that the high-valued regeneration can be realized. However, the prior art still suffers from significant drawbacks in handling certain types of polyesters, such as PETG. The PETG (polyethylene terephthalate-1, 4-cyclohexanedimethanol ester) has low crystallinity, poor thermal stability and high depolymerization difficulty due to the fact that a 1, 4-Cyclohexanedimethanol (CHDM) structural unit is introduced into the molecular chain of the PETG (polyethylene terephthalate-1, 4-cyclohexanedimethanol ester), and the traditional alcoholysis recovery method for PET is difficult to be efficiently applied. The current mainstream chemical recycling process focuses on conventional PET, and the lack of a targeted depolymerization strategy for modified polyesters such as PETG has significant bottlenecks in depolymerization efficiency, product purity and process energy consumption. Through searching, a chemical recovery method for waste PET products by utilizing the phase-change property of BHET crystals is disclosed, and the publication date is 2024, 10 months and 22 days. According to the method, ethylene glycol is used as an alcoholysis agent, waste PET is subjected to alcoholysis under the action of a catalyst to generate BHET, and the BHET is purified through steps of cooling crystallization, decompression sublimation and the like. While this technique optimizes the purification path of BHET, its core is still based on a single ethylene glycol system and is directed to standard PET substrates. For PETG containing CHDM structure, the alcoholysis product not only contains BHET, but also generates complex diol ester mixture containing cyclohexane structure, and it is difficult to effectively break all ester bonds through a single alcoholysis agent, and the product cannot form regular crystals, so that the method has incomplete depolymerization, difficult product separation and difficult realization of high-efficiency recovery when processing PETG. Through searching, a method for recycling waste polyester based on bi-component catalyst alcoholysis is disclosed with publication number CN114890898B, and the publication date is 2024, 4 and 16. According to the method, a bi-component catalyst consisting of a nitrogen-containing polycyclic organic matter and a metal salt is adopted, and ethylene glycol is used as a solvent for alcoholysis of PET at 120-200 ℃, so that the yield of BHET is improved. Although this technique synergistically improves the reaction efficiency by the catalyst, it is still limited to a single alcoholysis agent (ethylene glycol) system, not considering the selective cleavage ability of polyols synergistically to different ester bonds. The asymmetric ester bond formed by introducing CHDM in PETG molecule is sensitive to nucleophilicity and steric hindrance of alcoholysis reagent, single alcohol is difficult to attack terephthalic acid-ethylene glycol bond and terephthalic acid-CHDM bond simultaneously and efficiently, so that depolymerization rate is slow, side reaction is more, and monomer yield is low. In addition, the method does not couple depolymerization with the subsequent esterification process, and requires additional steps for product purification and repolymerization, so that the process is tedious and high in energy consumption. Disclosure of Invention In order to solve the technical problems mentioned in the background art, the invention provides a polyol gradient collaborative depolymerization-esterification coupling reaction device for PETG chemical recovery, which adopts the following technical scheme: Including main reation kettle, main reation kettle is vertical cylinder structure, and main reation kettle top fixedly connected with is sealed to be covered and is connected with a