CN113117628A

CN113117628A - Esterification reaction process and equipment for 1, 4-phthalic acid and 1, 4-butanediol

Info

Publication number: CN113117628A
Application number: CN202110430408.2A
Authority: CN
Inventors: 乌里希·提勒; 伯恩德·米勒
Original assignee: Bo EndeMile; Wu LixiTile
Current assignee: Bo EndeMile; Wu LixiTile
Priority date: 2021-04-21
Filing date: 2021-04-21
Publication date: 2021-07-16
Anticipated expiration: 2041-04-21
Also published as: CN113117628B

Abstract

The invention discloses an improved esterification process of 1, 4-phthalic acid and 1, 4-butanediol, which is characterized in that 1, 4-phthalic acid, 1, 4-butanediol and a commercial catalyst are fully mixed in a slurry mixer, then the slurry is sent to an esterification reactor for esterification, 1-3 steam generated by the reactor is sent to a separation system connected with the reactor, and part or all of tetrahydrofuran after water is separated out from the separation system or tetrahydrofuran from other sources is returned to the reactor, thus not only obtaining higher conversion rate, but also reducing the generation of tetrahydrofuran, and also providing production equipment suitable for the esterification process.

Description

Esterification reaction process and equipment for 1, 4-phthalic acid and 1, 4-butanediol

Technical Field

The invention relates to an esterification reaction process method of 1, 4-phthalic acid and 1, 4-butanediol and corresponding equipment thereof, in particular to a process for reducing byproduct tetrahydrofuran in esterification reaction and a device thereof.

Background

Esterification of dicarboxylic acids, such as 1, 4-benzodioxoic acid or dicarboxylic acid comonomers, with 1, 4-butanediol 1, 4-dihydrobutane is the first of the three reaction steps for the preparation of poly (1, 4-butylene terephthalate), esterification-prepolycondensation-polycondensation, wherein the 1, 4-phthalic acid can be partially or completely replaced by other dicarboxylic acids, such as butane diacid or hexane diacid acid.

In general, in the esterification reaction of the first step, 1, 4-butanediol (hereinafter referred to as DHB) and high-purity 1, 4-phthalic acid (hereinafter referred to as DBA) are mixed into a slurry in a ratio of 1 mole of DBA to 1.2 to 1.5 moles of DHB. A titanium-based catalyst is usually added to accelerate the reaction, wherein the concentration of titanium is in the range of 20 to 200 ppm.

The process is described in detail in Chinese patent CN101374882, with particular emphasis on the demonstration of an esterification reactor. The main reactor was equipped with vertically arranged heating tubes, a central tube with stirrer and a second, non-stirrer, back-flow chamber in the reactor shell to complete the esterification.

In operational practice, it is considered a disadvantage in terms of regulation that the stages of the reaction process are concentrated in a small space for lower equipment costs. This disadvantage is the imbalance in the management of the process and the poor accessibility of the process for maintenance when it is interrupted, as a result of which the cleaning work for removing contamination and deposits from the reactor becomes complicated.

Most of the existing processes for esterification of DBA and DHB seek to reduce the production of tetrahydrofuran as a by-product. Tetrahydrofuran is formed from DHB by cyclization and dehydration in acidic medium. The transitional esterification of methyl 1, 4-phthalate with DHB results in the formation of only a very small amount of tetrahydrofuran, on the order of a few percent by weight. In contrast, in esterification of DBA and DHB, up to 20% of DHB is converted to tetrahydrofuran. Thus, numerous patents describe how to reduce tetrahydrofuran formation during esterification.

U.S. patent 4,014,858 proposes the use of a catalyst based on a tetravalent organotin compound to reduce the formation of tetrahydrofuran.

U.S. Pat. No. 4,511,708 teaches that the esterification of DBA and DHB using conventional catalysts, the formation of tetrahydrofuran is reduced by the addition of at least one amide compound selected from the group consisting of urea and its derivatives, monocarboxylic acid amides having 1 to 9 carbon atoms, polycarboxylic acid amides having 1 to 9 carbon atoms, polyamides, phosphoric acid amides and sulfonic acid amides.

In U.S. Pat. No. 5,015,759, a method for reducing the production of tetrahydrofuran is: the reaction temperature is 180 ℃ and 245 ℃, and the reaction time is limited to 60-70 minutes. The molar ratio of ethylene glycol to dicarboxylic acid is at least 2: 1.

U.S. Pat. No. 5,064,935 teaches that a method for reducing the production of tetrahydrofuran as a by-product in the transitional esterification of methyl 1, 4-phthalate with DHB is to introduce an inert gas, such as nitrogen. Wherein nitrogen flows through the column reactor counter-currently to the reactants, thereby scrubbing off the by-products produced. The main disadvantages of this process are the consumption of nitrogen and the separation of gaseous by-products from nitrogen.

The above state of the art shows that there is a need for an improved process for the esterification of dicarboxylic acids, particularly DBA and DHB, which results in higher conversion rates while reducing the production of tetrahydrofuran.

Disclosure of Invention

The object of the present invention is to provide an improved process for the esterification of dicarboxylic acids, in particular 1,4-benzenedicarboxylic acid (DBA) and 1, 4-butanediol (DHB), which allows a higher conversion to be obtained while reducing the production of tetrahydrofuran.

Another object of the present invention is to provide a production apparatus suitable for the esterification process.

The esterification reaction process is characterized in that 1-3 steam generated by the reactors is sent to a separation system connected with the reactors, and part or all of tetrahydrofuran after water is separated out from the separation system or tetrahydrofuran from other sources is returned to the reactors.

In a preferred embodiment, the amount of water in the tetrahydrofuran returned to the reactor is 0.001 to 10% by weight, preferably 0.1 to 5% by weight. The tetrahydrofuran returned to the reactor is injected into the reaction mass from the bottom of the reactor and is vaporized either before entering the reactor or after contacting the reaction mass. The total amount of tetrahydrofuran returned to the reactor is equal to 10-300% of the tetrahydrofuran formed during the esterification reaction.

In a preferred embodiment, the catalyst is a titanium-based catalyst, and the content of titanium element is less than 200 ppm.

In a preferred scheme, the temperature difference between the reaction materials in the reactor and the heater is less than or equal to 80 ℃.

In a preferred embodiment, a chain branching agent and a heat stabilizer, which may be a chain branching agent for a trihydroxy compound such as glycerol, such as a heat stabilizer for triethylphosphonoacetate, are also added to the reaction mass or reactor.

In a preferred embodiment, the esterification product of the esterification process is fed to 1 to 2 reactors connected in series, prepolycondensation is carried out under a gradually decreasing pressure, and the prepolycondensation product is finally fed to a polycondensation reactor and finally polycondensation is carried out at a pressure of <5mbar to give a polyester product of the desired chain length with a corresponding viscosity in the range of 350 to 2000Pas (according to ISO11443 Feb 2021).

The equipment suitable for the process of the invention comprises 1-3 reactors, a separation system and a material conveying system, and is characterized in that the reactors are provided with a heater and a central pipe, the center of the central pipe is provided with a stirrer, the upper part of the reactor is connected with the separation system, the separation system consists of 2-4 distillation towers, the material output end of the separation system comprises a reaction material reflux end, a water output end and a tetrahydrofuran output end, after steam from the reactors is separated into 1, 4-butanediol, water and tetrahydrofuran, the 1, 4-butanediol reflows into the reactors through the material conveying system, and all or part of the separated tetrahydrofuran or tetrahydrofuran from other sources enters the bottoms of the reactors through the material conveying system.

Preferably, the heater in the reactor is a horizontally arranged ring-shaped heating tube or a vertically arranged heating tube.

The equipment configuration suitable for the process according to the invention can be a reactor equipped with horizontal heating pipes and an external material recirculation system equipped with a material pump and pipes and additional heaters (fig. 1), or a reactor equipped with vertical heating pipes but not equipped with an external material recirculation system consisting of pumps, pipes and additional heating pipes (fig. 2), or a reactor equipped with horizontal heating pipes but not equipped with an external material recirculation system consisting of material pumps, pipes and additional heating pipes (fig. 3).

The above-described arrangement may be a reactor with heating tubes and a stirrer, with or without a post-reactor equipped with a stirrer.

The invention can effectively reduce the generation of tetrahydrofuran by-products in the polymerization process and reduce unnecessary raw material loss.

Drawings

FIG. 1 is a schematic diagram of an apparatus and process flow according to one embodiment of the present invention.

FIG. 2 is a schematic diagram of an apparatus according to another embodiment of the present invention.

Fig. 3 is a schematic view of an apparatus according to a third embodiment of the present invention.

Detailed Description

The apparatus of fig. 1 comprises a reactor 11, an external circulation system, a separation system 17, a material transfer system and a post-reactor 18. The reactor 11 is used for carrying out esterification reaction on reaction materials. The post-reactor 18 further esterifies the product after the reaction in the reactor 11. The reactor 11 is provided with a horizontally arranged annular heating pipe 12 and a central pipe 13, and the center of the central pipe 13 is provided with a stirrer 14. An external circulation system is connected to the bottom of the reactor 11, in which a circulation pump 15 and a heat exchanger 16 as well as material supply lines are arranged. The upper part of the reactor 11 is connected to the input of a separation system 17. The separation system consists of 2 to 4 distillation columns. The separation system 17 is connected with a 1, 4-butanediol return pipe 19, a water output pipe and a tetrahydrofuran output pipe 20. A1, 4-butanediol return pipe 19 is connected to the upper portion of the reactor 11, and the separated 1, 4-butanediol is returned to the reactor 11. A tetrahydrofuran output pipe 20 is connected to the bottom of the reactor 11. The post-reactor 18 is also equipped with a horizontally arranged annular heating tube and a central tube, in the center of which is located a stirrer. The vapor chamber of the post-reactor 18 is connected to a separation system 17.

FIG. 2 shows another configuration of the apparatus of the present invention comprising a reactor 21, a separation system 27, a material transfer system and a post-reactor 28. In contrast to the apparatus of fig. 1, the heating tubes in the reactor 21 are replaced by a cluster of vertically arranged heating tubes 22. The apparatus of fig. 2 is not configured with an external circulation system. A tetrahydrofuran takeoff pipe 30 was connected to both the bottom of the reactor 21 and the bottom of the post-reactor 28, and the remaining constitution was the same as that of the apparatus of FIG. 1. In addition, a post-reactor 28 with a stirrer can be attached directly below the reactor 21 in order to save space.

Fig. 3 shows a third embodiment of the apparatus according to the invention, comprising a reactor 31 with horizontally arranged annular heating pipes 32, a separation system 37, a material conveying system and a post-reactor 38. The heating pipe 32 is supplied with a heat source from the heated heat medium oil. In contrast to the apparatus of FIG. 1, the apparatus of FIG. 3 is not equipped with an external circulation system, and the tetrahydrofuran outlet line 40 is connected to both the bottom of the reactor 31 and the bottom of the post-reactor 38. The rest of the construction is the same as the apparatus of fig. 1.

The process of the invention is that DBA and DHB are mixed and added with a commercial titanium catalyst, Dow Corning antifoaming agent 1510 and Blue powder toner Solvent Blue 104, and the mixture is fully mixed in a slurry mixer and then sent to a reactor 11 for esterification. The heating tube 12 and the stirrer 14 are activated to heat and stir the reaction mass, and in the reactor 11 of fig. 1 the temperature difference between the mass and the heating tube 12 is <15 c, preferably <10 c. In the reactor 21 of fig. 2 and the reactor 31 of fig. 3, the temperature difference between the material and the heating tube 22 or the heating tube 32 is preferably 10 to 80 ℃. The reactor 11 is connected to an external circulation system in which there are a circulation pump 15, a heat exchanger 16, and corresponding connecting pipes. A part of the reaction materials at the bottom of the reactor 11 are sent to a circulating pump 15, the circulating pump 15 sends the reaction materials back to the reactor 11 after heat exchange of a heat exchanger 16, and the temperature difference between a heating pipe of the heat exchanger 16 outside the reactor 11 and the reaction materials is less than or equal to 25 ℃, preferably less than or equal to 15 ℃. The time for the flow of material through the external heat exchanger 16 is <5 minutes, preferably <1 minute. The steam generated in the reactor 11 is sent to a separation system 17 to separate 1, 4-butanediol, water and tetrahydrofuran, the separated 1, 4-butanediol reflows to enter the reactor 11, the separated water is discharged, all or part of the separated tetrahydrofuran or tetrahydrofuran from other sources, the total amount of the tetrahydrofuran is equal to 10-300% of the tetrahydrofuran generated in the esterification reaction, the tetrahydrofuran is heated to more than 50 ℃, then enters the bottom of the reactor 11 through a material conveying system and is vaporized before entering the reactor or after contacting with reaction substances. Another portion of the purified tetrahydrofuran was collected from the outside. The esterification product produced in the esterification process is sent to one or two reactors connected in series to carry out pre-polycondensation under gradually reduced pressure. Finally, the resulting prepolycondensation is passed to a finishing reactor and the chemical process is ended. Wherein the desired chain lengths are prepared at a pressure <5mbar and corresponding high viscosities range between 350 and 2000Pas (ISO 11443 Feb 2021).

Comparative examples

DBA and DHB (molar ratio DHB/DBA of 1.1) were thoroughly mixed in a slurry mixer with the addition of a commercial Ti catalyst (titanium content 150 ppm), Dow Corning Antifoam 1510, and Blue toner Solvent Blue 104, and esterification of DBA and DHB was carried out in reactor 11 of FIG. 1. The reactor 11 is provided with a horizontally arranged annular heating pipe 12, a central pipe 13 and a stirrer 14 located in the center of the central pipe 13. At the bottom of the reactor 11, part of the reaction mass is sent to a circulation pump 15 and returned to the reactor 11 via a heat exchanger 16. The working temperature of the reactor material was 250 ℃, the temperature difference between the material in the reactor and the heating tube 12 was 15 ℃, and the temperature difference between the material and the heating tube in the heat exchanger outside the reactor 11 was 25 ℃. The residence time of the material in the external heat exchanger was 0.5 minutes. The tetrahydrofuran produced is entirely sent to a separation system 17 consisting of 4 distillation columns. Wherein the separated 1, 4-butanediol flows back into the reactor 11, water is discharged out, and the purified tetrahydrofuran is collected in a liquid collecting tank for later use. The reaction product from reactor 11 is piped to a separate, stirred after-reactor 18, the vapour chamber of which is in communication with a separation system 17. The reaction mass is prepolymerized under gradually reduced pressure. Finally, the resulting prepolycondensation product is passed to a finishing reactor, the chemical process being ended at a pressure of <5mbar, corresponding to a viscosity of about 1400 Pas (ISO 11443 Feb 2021).

Weighing the collected tetrahydrofuran by adopting a weighing method, and calculating to obtain the following components: 20% of the DHB is converted to tetrahydrofuran.

Example 1

DBA and DHB (molar ratio DHB/DBA of 1.1) were thoroughly mixed in a slurry mixer with the addition of a commercial Ti catalyst (titanium content 150 ppm), Dow Corning Antifoam 1510, and Blue toner Solvent Blue 104, and esterification of DBA and DHB was carried out in reactor 11 of FIG. 1. The reactor 11 is provided with a horizontally arranged annular heating pipe 12, a central pipe 13 and a stirrer 14 located in the center of the central pipe 13. At the bottom of the reactor, part of the reaction mass is sent to a circulation pump 15 and returned to the reactor 11 via a heat exchanger 16. The reactor contents were operated at a temperature of 250 ℃. The temperature difference between the material in the reactor and the heating tube 12 was 15 deg.c, and the temperature difference between the material and the heating tube in the heat exchanger outside the reactor was 25 deg.c. The residence time of the material in the external heat exchanger was 0.5 minutes. The tetrahydrofuran produced is entirely sent to a separation system 17 consisting of 4 distillation columns. Wherein the separated 1, 4-butanediol is refluxed into the reactor 11, drained outside, 30% of the tetrahydrofuran produced by the separation system and having a moisture content of 0.5% by weight is heated to 150 ℃ and recycled to the bottom of the reactor 11, while the remaining purified tetrahydrofuran leaves the separation system in overflow and is collected in an external storage tank. The reaction product from reactor 11 is piped to a separate, stirred after-reactor 18, the vapour chamber of which is in communication with a separation system 17. The reaction mass is prepolymerized under gradually reduced pressure. Finally, the resulting prepolycondensation product is passed to a finishing reactor, the chemical process being ended at a pressure of <5mbar, corresponding to a viscosity of about 1400 Pas (ISO 11443 Feb 2021).

Using the same weighing method as the comparative example, it was calculated that: 16.2% of DHB is converted to tetrahydrofuran.

Example 2

DBA and DHB (molar ratio DHB/DBA of 1.1) were thoroughly mixed in a slurry mixer with the addition of a commercial Ti catalyst (titanium content 150 ppm), Dow Corning Antifoam 1510, and Blue toner Solvent Blue 104, and then esterified in reactor 11 of FIG. 1. The reactor 11 is provided with a horizontally arranged annular heating pipe 12, a central pipe 13 and a stirrer 14 located in the center of the central pipe 13. At the bottom of the reactor, part of the reaction mass is sent to a circulation pump 15 and returned to the reactor 11 via a heat exchanger 16. The working temperature of the contents of the reactor 11 is 250 ℃. The temperature difference between the material in the reactor 11 and the heating tubes 12 was 15 deg.c, and the temperature difference between the material and the heating tubes was 25 deg.c in the heat exchanger 16 outside the reactor 11. The time for the flow of material through the external heat exchanger was 0.5 minutes. The resulting vapor was completely sent to a separation system 17 consisting of 4 distillation columns for separation, wherein the separated 1, 4-butanediol refluxed into the reactor 11, drained off to the outside, 200% of the total amount of tetrahydrofuran produced by the reaction, tetrahydrofuran having a water content of 0.5wt% heated to 150 ℃ and recycled to the bottom of the reactor 11, and the remaining purified tetrahydrofuran overflowed out of the separation system and collected in an external storage tank. The reaction product of the reactor 11 is sent to a post-reactor 18 for further reaction, the vapor chamber of which is in communication with a separation system 17. The reaction mass is prepolymerized under gradually reduced pressure. Finally, the resulting prepolycondensation product is passed to a finishing reactor, the chemical process being ended at a pressure of <5mbar, corresponding to a viscosity of about 1400 Pas (ISO 11443 Feb 2021).

Weighing all collected tetrahydrofuran by adopting a gravimetric method, calculating tetrahydrofuran generated by reaction, and calculating to obtain: 10.3% of DHB is converted to tetrahydrofuran.

Claims

1. An esterification process of 1, 4-phthalic acid and 1, 4-butanediol, wherein 1, 4-phthalic acid and 1, 4-butanediol and a commercial catalyst are fully mixed in a slurry mixer, and then the slurry is sent to an esterification reactor for esterification, and is characterized in that 1-3 steam generated by the reactor is sent to a separation system connected with the reactor, and part or all of tetrahydrofuran after water separation or tetrahydrofuran from other sources is returned to the reactor from the separation system.

2. The process as set forth in claim 1 wherein the tetrahydrofuran returning to the reactor is injected into the reaction mass from the bottom of the reactor and vaporized either before entering the reactor or after contacting the reaction mass.

3. The process as claimed in claim 1, wherein the tetrahydrofuran is returned to the reactor with a water content of 0.001 to 10% by weight, preferably 0.1 to 5% by weight.

4. A process according to any one of claims 1 to 3, characterized in that the total amount of tetrahydrofuran returned to the reactor is equal to 10-300% of the tetrahydrofuran produced during the reaction.

5. A process according to any one of claims 1 to 3, characterized in that the catalyst is a titanium based catalyst with an elemental titanium content of < 200 ppm.

6. A process according to any one of claims 1 to 3, wherein the temperature difference between the reaction mass in the reactor and the heater is less than or equal to 80 ℃.

7. A process according to any one of claims 1 to 3, wherein chain branching agents and thermal stabilisers are also added to the reaction mass or reactor.

8. A process according to any one of claims 1 to 3, wherein the esterified product is fed to 1 to 2 reactors connected in series and prepolycondensation is carried out under gradually decreasing pressure, and finally the prepolycondensation product is fed to a finishing reactor and polycondensed at a pressure of <5mbar to give a polyester product of the desired chain length, corresponding to a viscosity in the range of from 350 to 2000 Pas.

9. Apparatus suitable for use in any one of the processes of claims 1 to 8, comprising 1 to 3 reactors, a separation system and a material transport system, wherein the reactors are provided with a heater and a central tube, the central tube is provided with a stirrer in the center, the upper part of the reactor is connected with the separation system, the separation system comprises 2 to 4 distillation columns, the material output end of the separation system comprises a reaction material reflux end, a water output end and a tetrahydrofuran output end, after the steam from the reactor is separated into 1, 4-butanediol, water and tetrahydrofuran, the 1, 4-butanediol is refluxed into the reactor by the material transport system, and all or part of the separated tetrahydrofuran, or tetrahydrofuran from other sources, is introduced into the bottom of the reactor by the material transport system.

10. The apparatus as claimed in claim 9, wherein an external circulation system is connected to the bottom of the reactor, and the external circulation system comprises a circulation pump, a heat exchanger, and corresponding connecting pipes.

11. The apparatus of claim 9 or 10, wherein the heater in the reactor is a horizontally disposed annular heating tube or a vertically disposed heating tube.

12. Plant system for a process according to claims 1-3, which is equipped with a reactor equipped with horizontal heating pipes and with an external material recirculation system comprising a material pump and pipes and additional heaters (fig. 1), or with a reactor equipped with vertical heating pipes but not with an external material recirculation system consisting of pumps, pipes and additional heating pipes (fig. 2), or with a reactor equipped with horizontal heating pipes but not with an external material recirculation system consisting of a material pump, pipes and additional heating pipes (fig. 3).

13. Apparatus according to the process of claims 1-3, characterized by a reactor with heating tubes and a stirrer, with or without a post-reactor equipped with a stirrer.