A method and device for preparing high-purity 6PPD using crude antioxidant 6PPD

Abstract

This invention discloses a method and apparatus for producing high-purity 6PPD from crude antioxidant 6PPD. The method includes: using crude antioxidant 6PPD as raw material, separating light component impurities through thin-film evaporation to obtain high-purity 6PPD antioxidant; simultaneously, the separated light components are collected by condensation, and the solvent is recovered. The apparatus includes a falling film evaporator, a material transfer pump, a rotary thin-film evaporator, a vacuum trap, a gas-liquid separator, a Roots screw vacuum unit, and a condenser. The antioxidant 6PPD product obtained by this invention through thin-film evaporation has stable quality and a purity ≥98.5%, and the separated light components, such as 4-methyl-2-pentanone and 4-methyl-2-pentanol, can be recycled, improving economic efficiency while meeting environmental protection requirements.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical production process technology, specifically relating to a method and apparatus for producing high-purity 6PPD using crude antioxidant 6PPD. Background Technology

[0002] Antioxidant 6PPD (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) is one of the high-performance, general-purpose antioxidants among amine antioxidants. It provides good protection against thermo-oxidative and weathering aging and has a passivating effect on variable-valence metals. It is suitable for natural rubber, butadiene rubber, styrene-butadiene rubber, nitrile rubber, and chloroprene rubber. When used in combination with paraffin wax, it enhances static protection. It is the best choice for tire treads, sidewalls, inner tubes, and conveyor belts. It can also be used as a stabilizer for synthetic rubber. Due to its well-balanced anti-aging properties, antioxidant 6PPD has the largest usage among antioxidants, accounting for approximately 60%–70%, and holds a dominant position.

[0003] Currently, the industrial production process of antioxidant 6PPD, both domestically and internationally, mainly uses the reductive alkylation method. This involves condensation and reduction reactions of 4-aminodiphenylamine and methyl isobutyl ketone to obtain the antioxidant 6PPD. However, while the use of novel catalysts in existing technologies improves reaction selectivity and effectively suppresses the side reaction of MIBK (methyl isobutyl methanol) to MIBC (methyl isobutyl alcohol), thus increasing the conversion rate, it also suffers from technical drawbacks such as low product purity and insufficient solvent recovery. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method and apparatus for preparing high-purity 6PPD using crude antioxidant 6PPD. The method involves using crude antioxidant 6PPD as raw material, separating light component impurities through thin-film evaporation to obtain high-purity 6PPD antioxidant; simultaneously, the separated light components are collected by condensation, and the solvent is recovered.

[0005] The technical solution adopted in this invention is:

[0006] A method for preparing high-purity 6PPD using crude antioxidant 6PPD specifically includes the following steps:

[0007] (1) Crude antioxidant 6PPD enters the falling film evaporator 100 for primary evaporation. The liquid phase 6PPD at the bottom of the falling film evaporator is transported to the rotary thin film evaporator 300 by the material conveying pump 300 for secondary evaporation. The liquid phase at the bottom of the rotary thin film evaporator 300 is the 6PPD product, and the gas phase separated at the top enters the waste gas treatment system.

[0008] (2) The gas phase 6PPD separated by the falling film evaporator 100 is sequentially drawn into the Roots screw vacuum unit 600 through the vacuum collector 400 and the gas-liquid separator 500; the condensate at the bottom of the vacuum collector 400 and the gas-liquid separator 500 is sent to the solvent recovery system; the gas phase of the Roots screw vacuum unit 600 enters the condenser 700 for re-condensation and is then sent to the waste gas treatment system; the condensate at the bottom of the Roots screw vacuum unit 600 and the condensate at the bottom of the condenser 700 merge with the condensate at the bottom of the vacuum collector 400 and the gas-liquid separator 500 and are sent together to the solvent recovery system.

[0009] Furthermore, the crude antioxidant 6PPD contains N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine at a mass content of 50% to 60%, 4-methyl-2-pentanone at a mass content of 35% to 45%, and 4-methyl-2-pentanol at a mass content of 2% to 1%.

[0010] Furthermore, the temperature of the crude antioxidant 6PPD entering the falling film evaporator 100 is 80–150°C.

[0011] Furthermore, the temperature of the falling film evaporator 100 is 120–180°C, the absolute pressure is 30–50 kPa, the mass content of 6PPD in the liquid phase is 80%–90%, and the mass content of 4-methyl-2-pentanone and 4-methyl-2-pentanol in the gas phase 6PPD is 5%–10% and 1%–5%, respectively.

[0012] Furthermore, a condenser is provided on the upper part of the vacuum trap 400. After the gas phase 6PPD is cooled by the condenser, the temperature drops from 120-180℃ to 40℃ and enters the gas-liquid separator 500.

[0013] Furthermore, the absolute pressure of the Roots screw vacuum unit 600 is 30–50 kPa.

[0014] Furthermore, the temperature of the rotary thin-film evaporator 300 is 140–200°C, and the absolute pressure is 3–8 kPa.

[0015] Furthermore, the purity of the 6PPD product obtained by the rotary thin-film evaporator 300 is 98% to 98.5%.

[0016] Furthermore, the condensate sent to the solvent recovery system contains 95%–97% 4-methyl-2-pentanone and 1%–3% 4-methyl-2-pentanol by mass.

[0017] This invention also provides an apparatus for producing high-purity 6PPD using any of the above-mentioned methods of crude antioxidant 6PPD, comprising a falling film evaporator, a material conveying pump, a rotary thin film evaporator, a vacuum trap, a gas-liquid separator, a Roots screw vacuum unit, and a condenser; the liquid phase outlet at the bottom of the falling film evaporator is connected to the inlet of the material conveying pump via a pipeline, the outlet of the material conveying pump is connected to the feed inlet of the rotary thin film evaporator via a pipeline, and the gas phase outlet of the falling film evaporator is sequentially connected to the vacuum trap, the gas-liquid separator, the Roots screw vacuum unit, and the condenser via pipelines; a trapping condenser is provided in the upper part of the vacuum trap, and the vacuum trap, the gas-liquid separator, the Roots screw vacuum unit, and the condensate outlet at the bottom of the condenser are connected via pipelines and then connected to a solvent recovery system.

[0018] The beneficial effects of this invention are:

[0019] 1. The antioxidant 6PPD product obtained by the thin-film evaporation method of this invention has stable quality and purity ≥98.5%. Moreover, the separated light components such as 4-methyl-2-pentanone and 4-methyl-2-pentanol can be recycled, which improves economic benefits and meets environmental protection requirements.

[0020] 2. The device of the present invention has a simple process flow, is highly operable, and is suitable for industrial production. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of the present invention.

[0022] In the diagram: 100 - Falling film evaporator; 200 - Material conveying pump; 300 - Rotary thin film evaporator; 400 - Vacuum collector; 500 - Gas-liquid separator; 600 - Roots screw vacuum unit; 700 - Condenser. Detailed Implementation

[0023] The present invention will be further illustrated below with reference to the technical solution and accompanying drawings, but these examples do not limit the scope of protection of the present invention.

[0024] See Figure 1This invention provides an apparatus for producing high-purity 6PPD using crude antioxidant 6PPD, comprising a falling film evaporator 100, a material conveying pump 300, a rotary thin film evaporator 300, a vacuum trap 400, a gas-liquid separator 500, a Roots screw vacuum unit 600, and a phase inlet condenser 700. The liquid phase outlet at the bottom of the falling film evaporator 100 is connected to the inlet of the material conveying pump 300 via a pipeline, and the outlet of the material conveying pump 300 is connected to the feed inlet of the rotary thin film evaporator 300 via a pipeline. The gas phase outlet of the falling film evaporator 100 is sequentially connected to the vacuum trap 400, the gas-liquid separator 500, the Roots screw vacuum unit 600, and the condenser 700 via pipelines. The condensate outlets at the bottom of the vacuum trap 400, the gas-liquid separator 500, the Roots screw vacuum unit 600, and the condenser 700 are connected via pipelines and then connected to a solvent recovery system.

[0025] A trapping condenser is installed in the upper part of the vacuum trap 400. The trapping condenser is used to condense and cool the gas phase 6PPD entering the vacuum trap 400. Preferably, the temperature of the falling film evaporator 100 is 120-180℃ and the absolute pressure is 30-50kPa; the temperature of the rotary thin film evaporator 300 is 140-200℃ and the absolute pressure is 3-8kPa; and the absolute pressure of the Roots screw vacuum unit 600 is 30-50kPa.

[0026] Example

[0027] It should be noted that the percentage content in the following examples is by mass.

[0028] Example 1:

[0029] Crude 6PPD at 80℃, with a 6PPD mass content of 50%, a 4-methyl-2-pentanone mass content of 45%, and a 4-methyl-2-pentanol mass content of 2%, enters a falling film evaporator at a temperature of 120℃ and an absolute pressure of 30 kPa. Liquid 6PPD with a mass content of 80% is transported from the bottom of the falling film evaporator to a rotary thin film evaporator via a material transfer pump. This liquid 6PPD contains a 4-methyl-2-pentanone mass content of 10% and a 4-methyl-2-pentanol mass content of 5%. The gaseous light components such as 4-methyl-2-pentanone and 4-methyl-2-pentanol from the falling film evaporator are drawn into a vacuum collector. After passing through the vacuum collector, their temperature drops from 120°C to 40°C. The condensate at 40°C is sent from the bottom of the vacuum collector to the solvent recovery system. The gaseous phase at 40°C enters the gas-liquid separator. The liquid separated again is sent to the solvent recovery system. The gaseous phase from the gas-liquid separator is drawn into a Roots screw vacuum unit with an absolute pressure of 30 kPa. The liquid phase from the Roots screw vacuum unit is sent to the solvent recovery system. The gaseous phase from the Roots screw vacuum unit is condensed again by the condenser and then sent to the waste gas treatment system. The condensate is sent to the solvent recovery system. The liquid phase 6PPD from the material conveying pump enters the rotary thin film evaporator. After further evaporation, 6PPD product is obtained and sent to the storage system.

[0030] The condensate sent to the solvent recovery system was found to contain 95% 4-methyl-2-pentanone and 3% 4-methyl-2-pentanol, with a purity of 98% for the 6PPD product.

[0031] Example 2:

[0032] Crude 6PPD at 120℃, with a 6PPD content of 55%, a 4-methyl-2-pentanone content of 40%, and a 4-methyl-2-pentanol content of 1.5%, enters a falling film evaporator at a temperature of 150℃ and an absolute pressure of 40 kPa. Liquid 6PPD with a 6PPD content of 85% is pumped from the bottom of the falling film evaporator to a rotary thin film evaporator via a material transfer pump. This liquid 6PPD contains 8% 4-methyl-2-pentanone and 3% 4-methyl-2-pentanol. The light vapor components, such as 4-methyl-2-pentanone and 4-methyl-2-pentanol, from the falling film evaporator are drawn into a vacuum collector. After passing through the vacuum collector, their temperature decreases from 150°C to 40°C. The condensate at 40°C is sent to the recovery system from the bottom of the vacuum collector. The vapor phase at 40°C enters a gas-liquid separator, and the separated liquid is sent to the recovery system. The vapor phase from the gas-liquid separator is drawn into a Roots screw vacuum unit with an absolute pressure of 40 kPa. The liquid phase from the Roots screw vacuum unit is sent to the recovery system. The vapor phase from the Roots screw vacuum unit is condensed again in a condenser and then sent to the waste gas treatment system. The condensate is sent to the recovery system. The liquid phase 6PPD from the material transfer pump enters a rotary thin film evaporator. After further evaporation, 6PPD product is obtained and sent to the storage system.

[0033] The condensate sent to the solvent recovery system was found to contain 96% 4-methyl-2-pentanone and 2% 4-methyl-2-pentanol, with a purity of 98.2% for the 6PPD product.

[0034] Example 3:

[0035] Crude 6PPD at 150℃, with a 6PPD mass content of 60%, a 4-methyl-2-pentanone mass content of 35%, and a 4-methyl-2-pentanol mass content of 1%, enters a falling film evaporator at a temperature of 180℃ and an absolute pressure of 50 kPa. Liquid 6PPD with a mass content of 90% is then pumped from the bottom of the falling film evaporator to a rotary thin film evaporator via a material transfer pump. This liquid 6PPD contains 5% 4-methyl-2-pentanone and 1% 4-methyl-2-pentanol. The light vapor components, such as 4-methyl-2-pentanone and 4-methyl-2-pentanol, from the falling film evaporator are drawn into a vacuum collector. The temperature in the vacuum collector is reduced from 180°C to 40°C. The condensate at 40°C is sent to the recovery system from the bottom of the vacuum collector. The vapor phase at 40°C enters a gas-liquid separator, and the separated liquid is sent to the recovery system. The vapor phase from the gas-liquid separator is drawn into a Roots screw vacuum unit with an absolute pressure of 50 kPa. The liquid phase from the Roots screw vacuum unit is sent to the recovery system. The vapor phase from the Roots screw vacuum unit is condensed again in a condenser and then sent to the waste gas treatment system. The condensate is sent to the recovery system. The liquid phase 6PPD from the material transfer pump enters a rotary thin-film evaporator. After further evaporation, 6PPD product is obtained and sent to the storage system.

[0036] The condensate sent to the solvent recovery system was found to contain 97% 4-methyl-2-pentanone and 1% 4-methyl-2-pentanol, with a purity of 98.5% for the 6PPD product.

[0037] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing high-purity 6PPD using crude antioxidant 6PPD, characterized in that, Includes the following steps: (1) Crude antioxidant 6PPD enters the falling film evaporator (100) for primary evaporation. The liquid phase 6PPD at the bottom of the falling film evaporator is transported to the rotary thin film evaporator (300) for secondary evaporation via the material conveying pump (300). The liquid phase at the bottom of the rotary thin film evaporator (300) is the 6PPD product, and the gas phase separated at the top enters the waste gas treatment system. (2) The gas phase 6PPD separated by the falling film evaporator (100) is sequentially drawn into the Roots screw vacuum unit (600) through the vacuum collector (400) and the gas-liquid separator (500); the condensate at the bottom of the vacuum collector (400) and the gas-liquid separator (500) is sent to the solvent recovery system; the gas phase of the Roots screw vacuum unit (600) is sent to the waste gas treatment system after being condensed again in the condenser (700); the condensate at the bottom of the Roots screw vacuum unit (600) and the condensate at the bottom of the condenser (700) are combined with the condensate at the bottom of the vacuum collector (400) and the gas-liquid separator (500) and sent together to the solvent recovery system.

2. The method for preparing high-purity 6PPD using crude antioxidant 6PPD according to claim 2, characterized in that, The crude antioxidant 6PPD contains N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine at a mass content of 50%–60%, 4-methyl-2-pentanone at a mass content of 35%–45%, and 4-methyl-2-pentanol at a mass content of 2%–1%.

3. The method for preparing high-purity 6PPD using crude antioxidant 6PPD according to claim 2, characterized in that, The temperature of the crude antioxidant 6PPD entering the falling film evaporator (100) is 80-150℃.

4. The method for preparing high-purity 6PPD using crude antioxidant 6PPD according to claim 2, characterized in that, The temperature of the falling film evaporator (100) is 120-180℃, the absolute pressure is 30-50kPa, the mass content of 6PPD in the liquid phase is 80%-90%, and the mass content of 4-methyl-2-pentanone and 4-methyl-2-pentanol in the gas phase 6PPD is 5%-10% and 1%-5%, respectively.

5. A method for preparing high-purity 6PPD using crude antioxidant 6PPD according to claim 2, characterized in that, The vacuum trap (400) is equipped with a condenser at the top. After the gas phase 6PPD is cooled by the condenser, the temperature drops from 120-180℃ to 40℃ and enters the gas-liquid separator (500).

6. A method for preparing high-purity 6PPD using crude antioxidant 6PPD according to claim 2, characterized in that, The absolute pressure of the Roots screw vacuum unit (600) is 30-50 kPa.

7. A method for preparing high-purity 6PPD using crude antioxidant 6PPD according to claim 2, characterized in that, The temperature of the rotary thin-film evaporator (300) is 140-200℃ and the absolute pressure is 3-8kPa.

8. A method for preparing high-purity 6PPD using crude antioxidant 6PPD according to claim 2, characterized in that, The purity of the 6PPD product obtained by the rotary thin-film evaporator (300) is 98% to 98.5%.

9. A method for preparing high-purity 6PPD using crude antioxidant 6PPD according to claim 2, characterized in that, The condensate sent to the solvent recovery system contains 95%–97% 4-methyl-2-pentanone and 1%–3% 4-methyl-2-pentanol by mass.

10. An apparatus for a method of preparing high-purity 6PPD using crude antioxidant 6PPD as described in any one of claims 1 to 9, characterized in that, The system includes a falling film evaporator (100), a material conveying pump (300), a rotary thin-film evaporator (300), a vacuum trap (400), a gas-liquid separator (500), a Roots screw vacuum unit (600), and a condenser (700). The bottom liquid outlet of the falling film evaporator (100) is connected to the inlet of the material conveying pump (300) via a pipeline, and the outlet of the material conveying pump (300) is connected to the feed inlet of the rotary thin-film evaporator (300) via a pipeline. The vapor phase outlet of the generator (100) is connected in sequence to the vacuum trap (400), gas-liquid separator (500), Roots screw vacuum unit (600) and condenser (700) via pipelines. The upper part of the vacuum trap (400) is equipped with a trapping condenser. The condensate outlets at the bottom of the vacuum trap (400), gas-liquid separator (500), Roots screw vacuum unit (600) and condenser (700) are connected by pipelines and then connected to the solvent recovery system.

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