Continuous purification device for trioctyl trimellitate

Abstract

The utility model discloses a trioctyl trimellitate continuous purification device in the field of chemical equipment, which comprises a crude ester tank, a micro-channel reactor, a micro-filtration membrane separator, a nano-filtration membrane separator, an osmotic membrane filter and a finished product tank which are sequentially connected in series. According to the present invention, the salt is subjected to salt elution in the micro-filtration membrane separator, the heavy component is removed through the nano-filtration membrane separator, and the water is removed through the permeable membrane filter, such that the whole-process continuous purification is achieved, the batch interval of the traditional intermittent process is eliminated, and the device has advantages of low water consumption, high product purity and convenient production operation during the use.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of chemical equipment, in particular to a kind of trioctyl trimellitate continuous purification device. BACKGROUND

[0002] Trioctyl trimellitate (TOTM) is a commonly used high-temperature stabilizer, dispersant and plasticizer, which is widely used in the fields of coating industry, plastic industry and ink industry. In the production process of trioctyl trimellitate, various impurities may be mixed in. These impurities include residues in the reaction raw materials, by-products in the reaction process and a small amount of oligomers or other ester compounds. These impurities can affect the quality and performance of downstream products. The purpose of purification is to remove these by-products and improve the purity of trioctyl trimellitate.

[0003] Invention patent CN108610255A discloses a continuous production device and production process for trioctyl trimellitate. The production device and production process comprise an alcohol reflux circulation system consisting of three esterification devices and an alcohol-water separation tower. The product concentration is gradually increased by overflow, and finally trioctyl trimellitate is separated by a neutralization and alcohol removal tower. Continuous production can be realized. However, the equipment occupies a large area, the continuous operation parameters change a lot, and the operation is complex.

[0004] Invention patent CN103864620A discloses a production method for trioctyl trimellitate. In this method, nitrogen protection is used. After completing the di-esterification reaction and removing the reaction by-product water, a small amount of titanate catalyst is added to make the esterification reaction complete. The synthesized product does not need or only needs a small amount of neutralizing agent. However, during the process of adding water to destroy the titanate catalyst, the product acid value may exceed the standard due to reasons such as reverse acid. Post-treatment is needed to remedy the situation, which increases the production cost.

[0005] Invention patent CN110156599A discloses a preparation method for trimellitate. In this method, trimellitic anhydride and / or trimellitic acid are contacted with monohydric alcohols in the presence of a catalyst, and the generated water is removed at the same time. The catalyst is a bulk catalyst containing silicon, tin and oxygen, and contains Sn-O-Si bonds. It is easy to separate and can be recycled. This method improves the reaction conversion rate and selectivity. The solid-phase catalyst often leads to incomplete reaction due to insufficient contact during esterification, resulting in an increase in by-products. Traditional purification processes cannot meet the needs of this product.

[0006] The traditional TOTM purification process has the following problems:

[0007] 1. The purification time is long, the equipment utilization rate is low, the equipment occupies a large area, the continuous operation parameters change a lot, and the operation is complex.

[0008] 2. Traditional water washing method is difficult to completely remove trace amounts of acidic substances (such as unreacted trimellitic acid), the acid value of the finished product fluctuates greatly, and metal ions are easily introduced through the washing water, resulting in high color.

[0009] 3. Resource consumption is large, wastewater treatment cost is high, unreacted intermediates and octanol are difficult to completely recover, raw material utilization rate is low, and it is difficult to meet the market demand of low-price and environmentally-friendly plasticizer. Utility model content

[0010] The utility model aims at providing a trimellitic acid trioctyl ester continuous purification device, so that trimellitic acid trioctyl ester can be continuously purified, water consumption is small, product purity is high, and production operation is convenient.

[0011] The utility model discloses a trimellitic acid trioctyl ester continuous purification device, including crude ester jar, microchannel reactor, microfiltration membrane separator, nanofiltration membrane separator, permeation membrane filter and finished product jar, the crude ester jar upper portion is equipped with crude ester import, and the bottom is equipped with crude ester export, the crude ester export is connected to the import one of microchannel reactor through delivery pump one, the import two of microchannel reactor is used for supplying sodium hydroxide solution, be equipped with a plurality of microchannels for material mixing reaction in microchannel reactor, the outlet of microchannel converges to the static chamber, the bottom of static chamber is equipped with the water drain of control valve control, the side of static chamber is equipped with oil phase export, oil phase export is connected to the first stage feed port of microfiltration membrane separator through delivery pump two, still be equipped with first stage discharge port, first stage circulating water inlet, first stage circulating water outlet on microfiltration membrane separator, be equipped with microfiltration membrane in microfiltration membrane separator and separate oil phase with water phase, the first stage discharge port is connected to the second stage feed port of nanofiltration membrane separator through delivery pump three, be equipped with nanofiltration membrane in nanofiltration membrane separator, the membrane front channel one end of nanofiltration membrane is connected with the second stage feed port, and the other end is connected concentrated liquid export;The membrane rear channel of nanofiltration membrane is connected with the second stage discharge port on nanofiltration membrane separator, the second stage discharge port is connected with the third stage feed port on permeation membrane filter through delivery pump four, be equipped with permeation membrane in permeation membrane filter, the membrane front channel one end of permeation membrane is connected with third stage feed port, and the other end is connected with the third stage discharge port of permeation membrane filter, the third stage discharge port is connected with finished product jar, and the membrane rear channel of permeation membrane is connected with the third stage circulating water outlet of permeation membrane filter.

[0012] Further, the flow direction of the material in the microfiltration membrane separator is opposite to that of the circulating water. The salt, unreacted trimellitic acid, and trace amounts of phthalic acid in the material, which are partially dissolved in water, pass through the microfiltration membrane into the circulating water and are removed. Through countercurrent movement, the best removal effect is achieved.

[0013] Further, the static chamber is provided with a partition plate, a plurality of holes are arranged on the partition plate, and the oil phase outlet is located above the partition plate. The partition plate plays a role of stabilizing flow, the water separated by static separation is stored below the partition plate, and the oil phase is located above the partition plate. A detector can also be arranged on the partition plate, when the water level rises to the position of the partition plate, the water is discharged through the control valve to reduce the water level, so that the amount of water entrained in the discharge of the oil phase outlet is small.

[0014] Further, the control valve is a pneumatic disc valve. The static separated lower water can be discharged through intermittent opening of the pneumatic disc valve.

[0015] In the utility model, through the coarse ester tank, the microchannel reactor, the microfiltration membrane separator, the nanofiltration membrane separator, the osmotic membrane filter and the finished product tank which are connected in turn, the neutralization reaction is realized in the microchannel reactor, the acidic substances are removed, the corresponding separation membranes are respectively arranged in the microfiltration membrane separator, the nanofiltration membrane separator and the osmotic membrane filter, the whole constitutes a membrane separation assembly, the salt and the acid are eluted in the microfiltration membrane separator, then the heavy components are removed through the nanofiltration membrane separator, finally the moisture is removed through the osmotic membrane filter, the whole process continuous purification is realized, the batch interval of the traditional batch process is eliminated, and the full-continuous, low-energy-consumption and high-purity purification of trioctyl trimellitate is realized.

[0016] Compared with the prior art, the utility model has the advantages that:

[0017] 1. The microchannel reactor is prior art, the channel size is small (micron level), the specific surface area is up to 10 4  m 2 / m 3 , the mass transfer efficiency is better than that of the traditional process, and the reaction time is shortened to seconds. It is suitable for acid-base neutralization reaction, can complete mixing and reaction within 30 seconds, and reduces the generation of by-products. The impurities are separated by microfiltration, nanofiltration and osmotic evaporation membrane, the separation efficiency can reach 95%, and the product purity is high.

[0018] 2. After the microchannel reactor and the membrane assembly are connected in series, the whole process can be realized continuously, the batch interval of the traditional batch process is eliminated, the pressure drop of the microchannel reactor is low (<0.1MPa), the membrane separation does not need high temperature and high pressure, and the comprehensive energy consumption is lower than that of the traditional process; 80% of the washing water can be recycled by the membrane separation, and the water consumption in the whole section can be obviously reduced.

[0019] 3. The volume of the microchannel reactor is only 1 / 10 of that of the traditional stirred tank, the membrane assembly is modularly designed, and the overall land occupation is reduced by 50%. The production capacity can be quickly adjusted by increasing or decreasing the microchannel unit or the membrane assembly, and the production operation is convenient.

[0020] 4. The device can adjust the process parameters or filter medium according to the actual working condition or production demand during operation, covers various needs from basic production to high-end customization, reduces operating costs through energy-saving design, can also introduce new membrane materials (such as zeolite, mixed matrix membrane) to improve separation efficiency, and realizes lean production through dynamic parameter adjustment. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The flowchart of the utility model.

[0022] In the figure, 1 is a coarse ester tank, 2 is a microfiltration membrane separator, 201 is a microfiltration membrane, 202 is a first-stage discharge port, 203 is a first-stage circulating water inlet, 204 is a first-stage feed inlet, 205 is a first-stage circulating water outlet, 3 is a nanofiltration membrane separator, 301 is a nanofiltration membrane, 302 is a concentrated liquid outlet, 303 is a second-stage feed inlet, 304 is a second-stage discharge port, 4 is a permeation membrane filter, 401 is a permeation membrane, 402 is a third-stage feed inlet, 403 is a third-stage circulating water outlet, 404 is a third-stage discharge port, 5 is a microchannel reactor, 501 is a water discharge port, 502 is a control valve, 503 is an inlet one, 504 is an inlet two, 505 is a standing chamber, 506 is an oil phase outlet, 507 is a partition, 6 is a finished product tank, P1 is a conveying pump one, P2 is a conveying pump two, P3 is a conveying pump three, and P4 is a conveying pump four. DETAILED DESCRIPTION

[0023] As Figure 1As shown, it is a continuous purification device for trioctyl trimellitate, which mainly comprises a crude ester tank 1, a micro-channel reactor 5, a micro-filtration membrane separator 2, a nanofiltration membrane separator 3, a permeation membrane filter 4 and a finished product tank 6, the crude ester tank 1 is provided with a crude ester inlet at the upper portion and a crude ester outlet at the bottom portion, the crude ester outlet is connected to the inlet 503 of the micro-channel reactor 5 through a delivery pump P1, the inlet 504 of the micro-channel reactor 5 is used for feeding sodium hydroxide solution, a plurality of micro-channels for material mixing and reaction are arranged in the micro-channel reactor 5, the outlets of the micro-channels are collected to a standing chamber 505, the bottom portion of the standing chamber 505 is provided with a drain port 501 controlled by a control valve 502, the control valve 502 is a pneumatic disc valve; the side surface of the standing chamber 505 is provided with an oil phase outlet 506, the oil phase outlet 506 is connected to a first-stage feeding port 204 of the micro-filtration membrane separator 2 through a delivery pump P2, the micro-filtration membrane separator 2 is further provided with a first-stage discharging port 202, a first-stage circulating water inlet 203 and a first-stage circulating water outlet 205, the micro-filtration membrane separator 2 is provided with a micro-filtration membrane 201 for separating the oil phase from the water phase, the first-stage discharging port 202 is connected to a second-stage feeding port 303 of the nanofiltration membrane separator 3 through a delivery pump P3, the nanofiltration membrane separator 3 is provided with a nanofiltration membrane 301, one end of the front channel of the nanofiltration membrane 301 is connected to the second-stage feeding port 303, and the other end is connected to a concentrated liquid outlet 302; the rear channel of the nanofiltration membrane 301 is connected to a second-stage discharging port 304 on the nanofiltration membrane separator 3, the second-stage discharging port 304 is connected to a third-stage feeding port 402 on the permeation membrane filter 4 through a delivery pump P4, the permeation membrane filter 4 is provided with a permeation membrane 401, one end of the front channel of the permeation membrane 401 is connected to the third-stage feeding port 402, and the other end is connected to a third-stage discharging port 404 of the permeation membrane filter 4, the third-stage discharging port 404 is connected to the finished product tank 6, and the rear channel of the permeation membrane 401 is connected to a third-stage circulating water outlet 403 of the permeation membrane filter 4.

[0024] The flow direction of the material in the micro-filtration membrane separator 2 is opposite to that of the circulating water.

[0025] The standing chamber 505 is provided with a partition plate 507, a plurality of holes are arranged on the partition plate 507, and the oil phase outlet 506 is located above the partition plate 507.

[0026] The device is used for continuous purification of trioctyl trimellitate, and can be controlled in cooperation with various online detection instruments, such as an online water content analyzer, an online infrared analyzer, an online pH meter, an online water quality analyzer and an online gas chromatography system, etc., which are used for detecting indexes of each section, so as to accurately control the flow, and a flow control valve can also be arranged on the pipeline.

[0027] When the continuous purification device for trioctyl trimellitate is in operation, the purification is carried out according to the following flow:

[0028] (1) Neutralization and water washing section: the dealcoholized crude ester is pumped into the micro-channel reactor 5, the dealcoholized crude ester (temperature 60-70 DEG C) is pumped into the micro-channel reactor 5 at 200 L / h, and a volumetric metering pump is used to pump 10% NaOH solution (5 L / h) into the micro-channel reactor 5, after mixing reaction, the mixture is introduced into the standing chamber 505 to stand and stratify (residence time 20-30 minutes), an online pH probe is arranged at the lower end to track and detect, the lower water phase (pH 8-9) is discharged through the water outlet 501, and when the acid value of the upper oil phase is less than 0.1 mgKOH / g, the upper oil phase is pumped into the microfiltration membrane separator 2 through the delivery pump two P2.

[0029] (2) First-stage membrane separation section: the first-stage separation uses the microfiltration membrane separator 2, the temperature is controlled at 65-75 DEG C, the operating pressure is 0.3 MPa, and the cross-flow filtration mode is used, the crude ester flow is pumped into the first-stage membrane assembly at 150 L / h, the circulating water (which can be pure water) and the crude ester flow in countercurrent, the generated salt particles, unreacted trimellitic acid and a small amount of phthalic acid etc. pass through the microfiltration membrane 201 into the circulating water, and are further removed, the microfiltration membrane 201 uses a ceramic membrane (pore size 0.1-0.5 μm).

[0030] (3) Second-stage membrane separation section: the second-stage uses the nanofiltration membrane separator 3, the temperature is controlled at 65-75 DEG C, the nanofiltration membrane 301 has a pressure of 1.5 MPa, is made of polyamide composite membrane, has a molecular weight cut-off of 250 Da, and has an operating pressure range of 1.0-3.0 MPa, when the crude ester flows through the nanofiltration membrane 301, an online analyzer is arranged to test the ester content, metal ions and resistivity of the esterification liquid filtered by the second-stage membrane. The trioctyl trimellitate passes through the nanofiltration membrane 301 and enters the osmotic membrane filter 4, the concentrated liquid that cannot pass through the nanofiltration membrane 301 leaves from the concentrated liquid outlet 302, and can be subjected to post-treatment.

[0031] (4) Third-stage membrane separation section: the third-stage uses the osmotic membrane filter 4, the temperature is controlled at 75-90 DEG C, the pressure is -0.1 MPa, and the material is hydrophilic PVA composite membrane, the section dehydrates the esterification liquid to a water content of less than 0.1% and an alcohol content of less than 0.05%.

[0032] The continuous purification process has high flexibility, can be matched for purification treatment according to different impurity concentrations of raw materials, and has high product consistency through real-time adjustment of parameters by the DCS system.

[0033] The utility model is not limited to the above embodiment, on the basis of the technical scheme disclosed by the utility model, the skilled in the art can make some substitutions and deformation to some technical features without creative labor according to the disclosed technical content, and these substitutions and deformation are all within the protection scope of the utility model.

Claims

1. A continuous purification apparatus for trioctyl trimellitate, characterized by: The crude ester tank is provided with a crude ester inlet at the upper portion and a crude ester outlet at the bottom, the crude ester outlet is connected to the inlet one of the micro-channel reactor through a delivery pump one, the inlet two of the micro-channel reactor is used for feeding sodium hydroxide solution, a plurality of micro-channels for material mixing reaction are arranged in the micro-channel reactor, the outlets of the micro-channels are gathered to a standing chamber, a drain outlet controlled by a control valve is arranged at the bottom of the standing chamber, an oil phase outlet is arranged at the side of the standing chamber, the oil phase outlet is connected to the first-stage feed inlet of the micro-filtration membrane separator through a delivery pump two, the micro-filtration membrane separator is further provided with a first-stage discharge outlet, a first-stage circulating water inlet and a first-stage circulating water outlet, a micro-filtration membrane is arranged in the micro-filtration membrane separator to separate the oil phase from the water phase, the first-stage discharge outlet is connected to the second-stage feed inlet of the nanofiltration membrane separator through a delivery pump three, a nanofiltration membrane is arranged in the nanofiltration membrane separator, one end of the membrane front channel of the nanofiltration membrane is connected to the second-stage feed inlet, and the other end is connected to a concentrated liquid outlet; the membrane rear channel of the nanofiltration membrane is connected to the second-stage discharge outlet of the nanofiltration membrane separator, the second-stage discharge outlet is connected to the third-stage feed inlet of the permeation membrane filter through a delivery pump four, a permeation membrane is arranged in the permeation membrane filter, one end of the membrane front channel of the permeation membrane is connected to the third-stage feed inlet, and the other end is connected to the third-stage discharge outlet of the permeation membrane filter, the third-stage discharge outlet is connected to the product tank, and the membrane rear channel of the permeation membrane is connected to the third-stage circulating water outlet of the permeation membrane filter.

2. A continuous device for the purification of trioctyl trimellitate according to claim 1, characterized by the fact that: The flow direction of the material in the micro-filtration membrane separator is opposite to the flow direction of the circulating water.

3. A continuous device for purifying trioctyl trimellitate according to claim 1, characterized in that: A partition is arranged in the standing chamber, a plurality of holes are arranged on the partition, and the oil phase outlet is located above the partition.

4. A continuous device for the purification of trioctyl trimellitate according to any one of claims 1-3, characterized in that: The control valve is a pneumatic disc valve.

5. A continuous device for the purification of trioctyl trimellitate according to any one of claims 1-3, characterized in that: The micro-filtration membrane is a ceramic membrane with a pore size of 0.1-0.5 μm. The control valve is a pneumatic disc valve.

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