CN111909037B

CN111909037B - Continuous production method of tetraisooctyl pyromellitate

Info

Publication number: CN111909037B
Application number: CN202010903012.0A
Authority: CN
Inventors: 曲延涛; 孙国静; 董鹏; 张范
Original assignee: Weifang Hongrun New Materials Co ltd
Current assignee: Weifang Hongrun New Materials Co ltd
Priority date: 2020-09-01
Filing date: 2020-09-01
Publication date: 2023-04-18
Anticipated expiration: 2040-09-01
Also published as: CN111909037A

Abstract

The invention particularly relates to a continuous production method of tetraisooctyl pyromellitate. The tetraiso-octyl pyromellitate has good processing performance and high use safety, and the continuous production method is beneficial to expanding the productivity. The invention provides a production method for producing tetraisooctyl pyromellitate by continuous esterification. In addition, the invention optimizes the existing esterification catalyst to obtain a solid catalyst, thereby reducing the post-treatment difficulty. The process has stable operation and high productivity, and realizes the continuous production of the tetraisooctyl pyromellitate.

Description

Continuous production method of tetraisooctyl pyromellitate

Technical Field

The invention belongs to the technical field of production of tetraisooctyl pyromellitate, and particularly relates to a continuous production method of tetraisooctyl pyromellitate.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

Tetraoctyl pyromellitate (TOPM) is a high-performance environment-friendly plasticizer. Because the molecule contains four esterification groups, the coating has better durability and heat resistance. The low temperature flexibility, electrical insulation and high temperature resistance of the TOPM plasticized polyvinyl chloride resin are all far from those plasticized by the traditional plasticizers diisooctyl phthalate (DOP) and diisooctyl terephthalate (DOTP). From the 80 s of the 20 th century, western europe, the usa and the like gradually carried out investigation and research on physiological effects of phthalate plasticizers, and the research proves that phthalate esters have high extraction rate in plastic media and have hepatotoxicity, reproductive toxicity and carcinogenic teratogenicity on animals. As a non-o-benzene plasticizer, TOPM is the least toxic of all current aromatic plasticizers, and its plasticized products have been safely tested by the international general standard (SGS).

Based on excellent processability and safety of TOPM, the method has important economic significance for improving the synthesis process of the tetraisooctyl pyromellitate. However, the inventor finds that at present, the TOPM is mainly produced by adopting a batch process at home regardless of adopting a sulfuric acid and titanate liquid catalyst or a solid acid catalyst, but the consumption rate of raw materials for producing the TOPM in a batch mode is higher, a large amount of energy is consumed, the labor productivity is low, the productivity is low, and the product quality is not stable. In addition, the inventor also finds that the titanate catalyst (including tetrabutyl titanate, tetraisopropyl titanate and the like) which is commonly used at present can be decomposed into titanic acid and corresponding organic alcohol when contacting water, is easy to dissolve in a product, increases the subsequent treatment difficulty, is a liquid catalyst, is difficult to directly separate after being mixed with a liquid product, and influences the product purity.

Disclosure of Invention

Based on the technical current situation, the invention aims to provide a continuous production method of tetraisooctyl pyromellitate, which effectively improves the productivity. In addition, the invention also optimizes the existing titanate catalyst, provides a solid catalyst, not only can realize good catalytic efficiency, but also reduces the difficulty of subsequent treatment of the reaction.

Based on the technical effects, the invention provides the following technical scheme:

in a first aspect of the present invention, a continuous production method of tetraisooctyl pyromellitate is provided, which comprises the following steps: mixing pyromellitic dianhydride and isooctanol to obtain a pre-reaction liquid, adding the pre-reaction liquid into a continuous esterification reaction device to perform multi-stage esterification reaction to obtain a product liquid, and performing dealcoholization treatment on the product liquid.

Aiming at the problem of continuous production of tetraisooctyl pyromellitate, the invention designs a gradient addition mode of the catalyst, and the concentration of the catalyst is sequentially increased from the first-stage esterification reaction kettle to the last stage. The method effectively improves the utilization rate and the service life of the catalyst, and the conversion rate of pyromellitic dianhydride (pyromellitic anhydride) in the invention reaches more than 99.5 percent through verification, and can still reach more than 99 percent after 15 batches of intermittent experiments are repeated. In addition, the conventional continuous esterification reaction usually requires five or more esterification kettles to complete the full reaction of the materials. The invention can realize the conversion rate of more than 99 percent in the fourth-stage reaction kettle by reasonably adjusting the concentration gradient of the catalyst.

The invention improves the existing liquid titanate catalyst to obtain a solid catalyst which can be conveniently separated from reaction liquid and overcomes the defect of easy decomposition, so that the post-treatment process of the product only adopts dealcoholization under reduced pressure without the steps of neutralization, water washing, drying and the like, thereby greatly simplifying the post-treatment steps and reducing the generation of waste water.

The beneficial effects of one or more technical schemes are as follows:

the invention provides a continuous production method of tetraisooctyl pyromellitate, which pre-reacts two solid and liquid reaction materials to a homogeneous phase in front of an esterification reactor, so that the fluidity of the reaction materials is good, and better flowing and reaction can be ensured in the esterification reaction kettles connected in series in the next step. The invention realizes reaction continuity by a natural overflow mode, has simple working procedure and stable operation, produces stable product quality, can effectively improve the productivity and realizes the continuous production of the high-performance environment-friendly plasticizer, namely the tetraisooctyl pyromellitate.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is a schematic view of a continuous esterification reaction apparatus described in example 1;

wherein, 1 is a pre-reaction kettle, 201 is a No. 1 esterification reaction kettle, 202 is a No. 2 esterification reaction kettle, 203 is a No. 3 esterification reaction kettle, 204 is a No. 4 esterification reaction kettle, 210 is an overflow pipe, and 3 is a continuous dealcoholization tower.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

As introduced in the background art, aiming at the defects in the production process of tetraisooctyl pyromellitate in the prior art, the invention provides a continuous production method of tetraisooctyl pyromellitate in order to solve the technical problems.

In a first aspect of the present invention, a continuous production method of tetraisooctyl pyromellitate is provided, which comprises the following steps: mixing pyromellitic dianhydride and isooctanol to obtain a pre-reaction solution, adding the pre-reaction solution into a continuous esterification reaction device to perform multi-stage esterification reaction to obtain a product feed liquid, and performing dealcoholization treatment on the product feed liquid.

The chemical reaction equation mainly involved in the continuous production method is as follows:

preferably, the pyromellitic dianhydride is mixed with isooctyl alcohol according to a molar ratio of 1.

Preferably, the temperature of the esterification reaction is 170-225 ℃.

Preferably, the total time of the multistage esterification reaction is 8 to 10 hours.

Preferably, the catalyst for the multistage esterification reaction is SO ₄ ^2- A solid acid catalyst of the type/Ti-Mo-Al.

Aiming at the problems that the titanate catalyst is liquid at normal temperature and is difficult to separate from reaction liquid in the prior art, the invention optimizes the traditional catalyst, introduces Mo element as the core element of the composite metal oxide, and can effectively improve the efficiency and prolong the service life of the catalyst. According to the research and verification of the invention, al element in the catalyst is mainly used as a carrier element, and Ti and Mo elements play main catalytic activity.

Preferably, the continuous esterification reaction device comprises a pre-reaction kettle, a continuous esterification kettle and a dealcoholization treatment device; wherein the continuous esterification kettle is a series-connected N-stage esterification kettle, and N is more than or equal to 4.

Further preferably, in the pre-reaction kettle, the pyromellitic dianhydride and the isooctyl alcohol are stirred and mixed according to a proportion, the mixing temperature is 100-120 ℃, the mixing time is 30-60min, and the stirring speed during mixing is 350-450r/min.

Furthermore, a pump is arranged between the pre-reaction kettle and the continuous esterification kettle, and the pre-reaction liquid is transferred to the continuous esterification kettle through the pump.

Further preferably, the continuous esterification kettle is a four-stage esterification reaction kettle connected in series.

The continuous esterification reaction kettle is adopted as equipment in the prior art, and the reaction kettle can be different in detailed structure, but can realize the continuous production effect of the invention.

Furthermore, the temperature of the 1 st stage esterification reaction is 170-185 ℃, the temperature of the 2 nd stage esterification reaction is 185-195 ℃, the temperature of the 3 rd stage esterification reaction is 195-205 ℃, and the temperature of the 4 th stage esterification reaction is 205-215 ℃.

Furthermore, the amount of the catalyst added in the 1 st stage esterification reaction is 0.0wt.% to 1.5wt.% of the pre-reaction feed liquid, the amount of the catalyst added in the 2 nd stage esterification reaction is 2wt.% to 3.5wt.% of the pre-reaction feed liquid, the amount of the catalyst added in the 3 rd stage esterification reaction is 4wt.% to 5.5wt.% of the pre-reaction feed liquid, and the amount of the catalyst added in the 4 th stage esterification reaction is 6wt.% to 7.5wt.% of the pre-reaction feed liquid.

The research of the invention proves that the catalyst content in the first-stage reaction kettle is lower, even no catalyst exists, the material can esterify a large part, the catalyst content in the second-stage esterification kettle is gradually increased, the gradient adding mode can effectively improve the catalyst utilization rate and prolong the service life of the catalyst.

Furthermore, the height of the four-stage esterification kettle is reduced in sequence, the side wall of the esterification kettle is provided with an overflow pipe communicated with the next-stage esterification kettle each time, and a filter membrane covering the inner diameter of the pipe wall is arranged in the overflow pipe.

According to the invention, the catalyst is optimized to be solid, and the catalyst can be fixed in the reaction kettle by arranging the filter membrane in the overflow pipe, so that the operation that the catalyst needs to be repeatedly added after flowing into the next-stage reaction kettle along with the material is avoided.

Further preferably, the dealcoholization treatment device is a continuous dealcoholization tower, and the dealcoholization operation conditions are as follows: the vacuum degree is 60-80 Kpa, and the temperature is 100-140 ℃.

Preferably, after the continuous dealcoholization, the acid value of the final product feed liquid is less than 0.15mgKOH/g.

In order to make the technical scheme of the present invention more clear to those skilled in the art, the technical scheme of the present invention will be described in detail with reference to specific examples, and the reagents described in the following examples are all commercially available products unless otherwise specified.

Example 1

In this embodiment, the continuous esterification apparatus includes a pre-reaction kettle 1, a continuous esterification kettle, and a continuous dealcoholization tower 3; the cauldron of esterifying in succession is the fourth grade cauldron of esterifying, is established ties by 1 number esterification reaction cauldron 201, 2 numbers esterification reaction cauldron 202, 3 numbers esterification reaction cauldron 203, 4 numbers esterification reaction cauldron 204 and forms, each grade is esterified and is connected through overflow pipe 210 between cauldron and the next-level, set up the filter membrane that covers the internal diameter cross-section in the overflow pipe 210 pipe wall.

The bottom of the esterification kettle 201 to 204 is provided with a sampling port, and the bottom of the pre-reaction kettle 1 is provided with a three-way valve. The opening and closing of the sampling port are controlled by the valve, so that the reaction liquid in the esterification kettle can be conveniently sampled for detection, and the esterification kettle can be used for replacing the catalyst.

Adding pyromellitic dianhydride and isooctanol into a pre-reaction kettle 1 according to the molar ratio of 1; conveying the pre-reaction liquid from the pre-reaction kettle to the No. 1 esterification reaction kettle through a pump, wherein the amounts of the catalysts added in the No. 1 to No. 4 esterification reaction kettles are 0wt.%, 2wt.%, 4wt.% and 6wt.% of the pre-reaction liquid. Along with the continuous addition of material, when No. 1 reation kettle's reaction material reached the overflow pipe of cauldron top, continued the reaction to No. 2 esterification reaction cauldron through the pipeline natural overflow, same mode, when No. 2 reation kettle's reaction material reached the overflow pipe of cauldron top, continued the reaction to No. 3 esterification reaction cauldron through the pipeline natural overflow to analogize in this way. The reaction mass finally flows into the No. 4 esterification reaction kettle. The temperature of each stage of reaction kettle is as follows: the reaction temperature of the 1-stage reaction kettle is 175 ℃, the reaction temperature of the 2-stage reaction kettle is 185 ℃, the reaction temperature of the 3-stage reaction kettle is 195 ℃, and the reaction temperature of the 4-stage reaction kettle is 205 ℃. And finally, the acid value of the material discharged from the 4 th-stage esterification reaction kettle is less than 0.15mgKOH/g. The feed liquid after the reaction is subjected to continuous dealcoholization treatment in a continuous dealcoholization tower 3.

The esterification catalyst is SO ₄ ^2- The catalyst is a solid acid catalyst of a/Ti-Mo-Al type, and the preparation process of the catalyst comprises the following steps: at room temperature, salt solution containing titanium sulfate and aluminum nitrate nonahydrate (molar mass fraction of Ti is 38%) is mixed uniformly, pH value is adjusted to 8-9 by ammonia water solution, precipitate is filtered and washed, dried and ground. Adding 0.5mol/L molybdenum sulfate solution into the ground powder, soaking for 2h under the reflux state, filtering and drying, soaking for 1h by using 1mol/L dilute sulfuric acid solution, filtering, drying at 130-150 ℃, roasting at 750-800 ℃ for 3 h, and storing under the drying condition.

Example 2

Adding pyromellitic dianhydride and isooctanol into a pre-reaction kettle according to the molar ratio of 1; conveying the pre-reaction liquid from the pre-reaction kettle to the No. 1 esterification reaction kettle through a pump, wherein the amounts of the catalysts added from the No. 1 esterification reaction kettle to the No. 4 esterification reaction kettle are 1wt.%, 2.5wt.%, 4.5wt.% and 6.5wt.% of the pre-reaction liquid. Along with the continuous addition of material, when No. 1 reation kettle's reaction material reached the overflow pipe of cauldron top, continued the reaction to No. 2 esterification reaction cauldron through the pipeline natural overflow, same mode, when No. 2 reation kettle's reaction material reached the overflow pipe of cauldron top, continued the reaction to No. 3 esterification reaction cauldron through the pipeline natural overflow to analogize in this way. The reaction mass finally flows into the No. 4 esterification reaction kettle. The temperature of each stage of reaction kettle is as follows: the reaction temperature of the 1-stage reaction kettle is 180 ℃, the reaction temperature of the 2-stage reaction kettle is 190 ℃, the reaction temperature of the 3-stage reaction kettle is 200 ℃, and the reaction temperature of the 4-stage reaction kettle is 205 ℃. And finally, the acid value of the material from the 4 th-stage esterification reaction kettle is less than 0.15mgKOH/g. The feed liquid after the reaction is subjected to continuous dealcoholization treatment in a continuous dealcoholization tower 3.

Example 3

Adding pyromellitic dianhydride and isooctanol into a pre-reaction kettle according to the molar ratio of 1; conveying the pre-reaction liquid from the pre-reaction kettle to the No. 1 esterification reaction kettle through a pump, wherein the amounts of catalysts added from the No. 1 esterification reaction kettle to the No. 4 esterification reaction kettle are 1.5wt.%, 3wt.%, 5wt.% and 7wt.% of the pre-reaction liquid. Along with the continuous addition of material, when No. 1 reation kettle's reaction mass reached the overflow pipeline of cauldron top, continued the reaction to No. 2 esterification reaction cauldron through the natural overflow of pipeline, same mode, when No. 2 reation kettle's reaction mass reached the overflow pipeline of cauldron top, continued the reaction to No. 3 esterification reaction cauldron through the pipeline natural overflow, analogize with this. The reaction mass finally flows into the No. 4 esterification reaction kettle. The temperature of each stage of reaction kettle is as follows: the reaction temperature of the 1-stage reaction kettle is 185 ℃, the reaction temperature of the 2-stage reaction kettle is 195 ℃, the reaction temperature of the 3-stage reaction kettle is 205 ℃, and the reaction temperature of the 4-stage reaction kettle is 215 ℃. And finally, the acid value of the material discharged from the 4 th-stage esterification reaction kettle is less than 0.15mgKOH/g. The feed liquid after the reaction is subjected to continuous dealcoholization treatment in a continuous dealcoholization tower 3.

Example 4

Adding pyromellitic dianhydride and isooctanol into a pre-reaction kettle according to the molar ratio of 1; conveying the pre-reaction liquid from the pre-reaction kettle to the No. 1 esterification reaction kettle through a pump, wherein the amounts of the catalysts added from the No. 1 esterification reaction kettle to the No. 4 esterification reaction kettle are 1.5wt.%, 3.5wt.%, 5.5wt.% and 7.5wt.% of the pre-reaction liquid. Along with the continuous addition of material, when No. 1 reation kettle's reaction mass reached the overflow pipeline of cauldron top, continued the reaction to No. 2 esterification reaction cauldron through the natural overflow of pipeline, same mode, when No. 2 reation kettle's reaction mass reached the overflow pipeline of cauldron top, continued the reaction to No. 3 esterification reaction cauldron through the pipeline natural overflow, analogize with this. The reaction mass finally flows into the No. 4 esterification reaction kettle. The temperature of each stage of reaction kettle is as follows: the reaction temperature of the 1-stage reaction kettle is 185 ℃, the reaction temperature of the 2-stage reaction kettle is 195 ℃, the reaction temperature of the 3-stage reaction kettle is 205 ℃, and the reaction temperature of the 4-stage reaction kettle is 215 ℃. And finally, the acid value of the material discharged from the 4 th-stage esterification reaction kettle is less than 0.15mgKOH/g. The feed liquid after the reaction is subjected to continuous dealcoholization treatment in a continuous dealcoholization tower 3.

TABLE 1 data on the change in acid number in the examples (sampling 6h after stabilization of the system)

As can be seen from the results in Table 1, in the continuous esterification reaction kettles in examples 1-4, the acid value of the esterification kettle No. 4 can be reduced to below 0.15mgKOH/g, which proves that the time required by the reaction can be shortened and the investment of esterification equipment can be reduced by the gradient feeding mode, and the reaction cost can be saved.

This example also deals with the SO described in example 1 ₄ ^2- The service life of the solid acid catalyst of the type/Ti-Mo-Al was examined and the results are shown in Table 2:

TABLE 2 change in acid value of reaction feed at each time point in example 3

SO is shown in Table 2 ₄ ^2- The relationship between the operation time of the/Ti-Mo-Al catalyst in the reaction kettle and the acid value in the reaction kettle can be seen from the data in Table 2, the acid value of the solution system in each reaction kettle is basically kept unchanged during the operation of the catalyst provided in example 1 for 6h to 30d, the catalyst is proved to be hardly reduced after continuous operation for 30d, and the service life of the catalyst is proved to be at least more than 30 d. The invention verifies that the stable operation time of the catalyst can reach more than half a year in the actual production process, the service life of the catalyst is obviously prolonged, and the production cost of enterprises can be effectively reduced.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A continuous production method of tetraisooctyl pyromellitate is characterized by comprising the following steps: mixing pyromellitic dianhydride and isooctanol to obtain a pre-reaction liquid, adding the pre-reaction liquid into a continuous esterification reaction device to perform multi-stage esterification reaction to obtain a product liquid, and performing dealcoholization treatment on the product liquid; the catalyst of the multistage esterification reaction is SO ₄ ^2- A solid acid catalyst of the type/Ti-Mo-Al; the continuous esterification reaction device comprises a pre-reaction kettle, a continuous esterification kettle and a dealcoholization treatment device; wherein the continuous esterification kettle is a series-connected N-stage esterification kettle, and N is more than or equal to 4; the heights of the N-stage esterification kettles are sequentially reduced, an overflow pipe is arranged on the side wall of each esterification kettle and communicated with the next-stage esterification kettle, and a filter membrane covering the inner diameter of the pipe wall is arranged in the overflow pipe; the continuous esterification kettle is series-connected four-stage esterA chemical reaction kettle; the temperature of the 1 st stage esterification reaction is 170-185 ℃, the temperature of the 2 nd stage esterification reaction is 185-195 ℃, the temperature of the 3 rd stage esterification reaction is 195-205 ℃, and the temperature of the 4 th stage esterification reaction is 205-215 ℃; the amount of the catalyst added in the 1 st stage esterification reaction is 0.0-1.5 wt% of the pre-reaction feed liquid, the amount of the catalyst added in the 2 nd stage esterification reaction is 2-3.5 wt% of the pre-reaction feed liquid, the amount of the catalyst added in the 3 rd stage esterification reaction is 4-5.5 wt% of the pre-reaction feed liquid, and the amount of the catalyst added in the 4 th stage esterification reaction is 6-7.5 wt% of the pre-reaction feed liquid.

2. The continuous production method of tetraisooctyl pyromellitate according to claim 1, wherein the pyromellitic dianhydride is mixed with isooctyl alcohol in a molar ratio of 1.

3. The continuous production method of tetraisooctyl pyromellitate according to claim 1, wherein the temperature of the esterification reaction is 170-225 ℃.

4. The continuous production method of tetraisooctyl pyromellitate according to claim 1, wherein the total time of the multistage esterification reaction is 8 to 10 hours.

5. The continuous production method of tetraisooctyl pyromellitate according to claim 1, wherein the pyromellitic dianhydride and isooctyl alcohol are mixed in a pre-reaction tank with stirring at 100 to 120 ℃ for 30 to 60min at a stirring speed of 350 to 450r/min; and a pump is arranged between the pre-reaction kettle and the continuous esterification kettle, and the pre-reaction liquid is transferred to the continuous esterification kettle through the pump.

6. The continuous production method of tetraisooctyl pyromellitate according to claim 1, wherein the dealcoholization treatment apparatus is a continuous dealcoholization tower, and the dealcoholization operation conditions are: the vacuum degree is 60 to 80Kpa, and the temperature is within the range of 100 to 140 ℃.

7. The continuous production method of tetraisooctyl pyromellitate according to claim 1, wherein after the dealcoholization, the acid value of the final product solution is less than 0.15mgKOH/g.