WO2024099083A1 - 一种低单苯环类杂质含量的粗异氰酸酯的生产工艺 - Google Patents

一种低单苯环类杂质含量的粗异氰酸酯的生产工艺 Download PDF

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WO2024099083A1
WO2024099083A1 PCT/CN2023/126665 CN2023126665W WO2024099083A1 WO 2024099083 A1 WO2024099083 A1 WO 2024099083A1 CN 2023126665 W CN2023126665 W CN 2023126665W WO 2024099083 A1 WO2024099083 A1 WO 2024099083A1
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stripping
tower
crude isocyanate
isocyanate
crude
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PCT/CN2023/126665
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English (en)
French (fr)
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周宇杰
黄荐
李超群
文放
董超
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万华化学（宁波）有限公司
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Publication of WO2024099083A1 publication Critical patent/WO2024099083A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C263/00—Preparation of derivatives of isocyanic acid
    • C07C263/18—Separation; Purification; Stabilisation; Use of additives
    • C07C263/20—Separation; Purification
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C265/00—Derivatives of isocyanic acid
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C265/00—Derivatives of isocyanic acid
    • C07C265/14—Derivatives of isocyanic acid containing at least two isocyanate groups bound to the same carbon skeleton

Definitions

  • the invention relates to the technical field of isocyanate production, and in particular to a production process of crude isocyanate with low content of monobenzene ring impurities.
  • Isocyanates are widely used in the synthesis and production of products such as shoe sole stock solution, polyurethane foam, thermal insulation materials, and artificial leather. Isocyanates are mainly prepared by the phosgene method. The corresponding amines are mixed with an inert solvent and then fully mixed with phosgene for phosgenation reaction to obtain a photochemical reaction liquid. The photochemical reaction liquid is subjected to phosgene removal and solvent removal to obtain a crude isocyanate. In the process of producing polymethylene polyphenyl polyisocyanates, since the raw material amine usually contains a small amount of monophenyl ring amine substances, the crude isocyanate produced contains monophenyl ring isocyanate or its derivatives.
  • the monophenyl ring isocyanate or its derivatives have a lower boiling point and lower reaction activity. In the subsequent separation process of the crude isocyanate, it is easy to remain in the product, resulting in a certain amount (usually 800-3000ppm) of monophenyl ring isocyanate or its derivatives in the polymethylene polyphenyl polyisocyanate product, which may be harmful to the health of users.
  • CN107652208A discloses a method and system for removing solvent from an isocyanate product obtained by phosgenation reaction, wherein the solvent in the isocyanate product is removed by using a tower with different forms of tower internals. A random packing tower is used to remove the solvent component in the isocyanate product.
  • the patent does not describe the removal effect of monophenyl ring isocyanate and derivatives in the isocyanate product in the process, and the stripping process will cause partial isocyanate loss.
  • CN108586706A discloses a method for purifying isocyanate, specifically relates to low A method for preparing isocyanates with a low chlorine content.
  • the chlorinated derivatives and solvents in the isocyanates are removed by stripping by introducing an inert gas at normal pressure.
  • the patent provides a process for stripping crude isocyanates to remove light components by using hot nitrogen.
  • the content of the single benzene ring impurity component is very low, if the single benzene ring impurity component needs to be completely removed, a large amount of crude isocyanate will be entrained in the gas phase during the stripping process.
  • the mixture of this part of isocyanate and the multi-benzene ring impurity component needs to be circulated back to the system to reduce the loss of crude isocyanate, resulting in the accumulation of the single benzene ring impurity component in the system and the formation of a dynamic equilibrium, which limits the complete removal of the single benzene ring impurity component in the crude isocyanate.
  • the object of the present invention is to provide a production process for crude isocyanate with low content of monobenzene ring impurities, which can effectively reduce the difficulty of separating monobenzene ring impurity components from crude isocyanate, realize simple recovery of high-purity crude isocyanate, and greatly reduce the loss of crude isocyanate.
  • a production process of crude isocyanate with low content of monophenyl ring impurities comprising the following steps:
  • the monobenzene ring impurities in the crude isocyanate are halogenated monobenzene ring substances, selected from at least any one of monochlorophenyl isocyanate, dichlorophenyl isocyanate, trichlorophenyl isocyanate, monobromophenyl isocyanate, dibromophenyl isocyanate and tribromophenyl isocyanate; preferably, the content of the monobenzene ring impurities in the crude isocyanate is 800-2000ppm.
  • the low boiling point inert organic matter in step 1) is selected from at least one of carbon tetrachloride, chloroform, dichloromethane and monochloromethane; preferably, the stripping agent is used in an amount of 0.01-0.02 Nm 3 /h per ton of crude isocyanate, preferably 0.013-0.017 Nm 3 /h per ton of crude isocyanate.
  • the operating temperature of the stripping tower in step 1) is 160-220°C, preferably 170-210°C, more preferably 180-200°C; the operating pressure is controlled at 10-100 kPa, preferably 30-80 kPa, more preferably 50-60 kPa.
  • the mass content of isocyanate in the top gas phase of the stripping tower in step 1) is 1-5%, preferably 2-4%; preferably, the content of monophenyl ring impurities in the crude isocyanate obtained at the bottom of the stripping tower in step 1) is 10-1000ppm, preferably 100-500ppm.
  • the gas phase of the mixture taken out from the top of the stripping tower in step 2) is cooled in a condenser to form a liquid phase, and the cooling temperature of the heat exchanger is controlled at 10-50°C, preferably 20-40°C.
  • the bottom temperature of the distillation tower is 220-300° C., preferably 220-260° C.; the operating pressure is controlled at 70-150 kPa, preferably 80-110 kPa.
  • the stripping agent steam obtained from the top of the distillation tower in step 2) has a single benzene ring impurity content of less than 500 ppm, preferably less than 200 ppm, and more preferably less than 150 ppm; preferably, the stripping agent steam extracted from the top of the distillation tower is directly introduced into the stripping tower in step 1) for use as stripping steam.
  • the amount of the single benzene ring impurity product extracted from the tower in step 2) accounts for 3.5%-4.2% of the mass ratio of the tower feed amount, preferably 3.9%-4.1%, the content of low-boiling inert organic matter in the extracted product is less than 50000 ppm, preferably less than 5000 ppm; the crude isocyanate content is less than 3%, preferably less than 2%; preferably, the pure single benzene ring impurity product extracted and concentrated from the tower is directly treated as waste liquid.
  • the mass content of monophenyl ring impurities in the crude isocyanate obtained in the distillation tower kettle in step 2) is less than 5%, preferably less than 3%; preferably, the crude isocyanate obtained by distillation can be directly recovered into the crude isocyanate product for use.
  • the present invention has the following beneficial effects:
  • the production process of the invention adopts low-boiling-point inert organic matter as stripping gas, strips crude isocyanate in a stripping tower to remove single benzene ring impurity components, and the removed single benzene ring impurity components, the low-boiling-point organic matter used for stripping and the entrained crude isocyanate are condensed in a condenser at the top of the stripping tower to form a mixture, and then the single benzene ring impurity components/stripping agent and the crude isocyanate are separated at the bottom of the tower through a rectification tower, and the high-purity crude isocyanate is recovered.
  • the stripping agent and the single benzene ring impurities are separated at the top of the tower, and the formed stripping agent steam can be directly introduced into the bottom of the stripping tower for stripping, and the concentrated single benzene ring impurities are taken out of the tower and treated as waste liquid.
  • the low-boiling-point inert organic matter used for stripping has good solubility for single benzene ring impurities, and in a mixture formed by single benzene ring impurities and isocyanate, can improve the separation degree of single benzene ring impurity components and crude isocyanate, effectively reduce the difficulty of separating single benzene ring impurity components from crude isocyanate, and realize the recovery of high-purity crude isocyanate;
  • the low-boiling-point inert stripping agent and the single benzene ring impurity components can be recovered in the form of distillation to obtain the inert stripping agent, and the operating conditions of the distillation tower are controlled so that the inert stripping agent steam with higher purity is directly extracted from the top of the distillation tower, and the obtained inert stripping agent steam has a more suitable pressure and can be directly used for the stripping of crude isocyanate, so that the inert stripping agent can be circulated in the
  • the production process of the invention is simple and efficient, and is particularly suitable for industrial applications.
  • FIG1 is a schematic diagram of a production process of a crude isocyanate with low monophenyl ring impurity content according to the present invention.
  • 1 is a crude isocyanate raw material
  • 2 is a stripping agent
  • 3 is a mixed gas phase
  • 4 is a crude isocyanate with a low content of monophenyl ring impurities after stripping
  • 5 is a mixed liquid phase
  • 6 is a stripping agent steam steam
  • 8 crude isocyanate
  • a production process of a crude isocyanate with low monophenyl ring impurity content comprises the following steps:
  • a crude isocyanate raw material 1 flows from the top of the stripping tower 10 from top to bottom, and low-boiling-point inert organic vapor flows upward from bottom to top as a stripping agent 2, and monophenyl ring impurities in the crude isocyanate are stripped and transferred to the gas phase;
  • a mixed gas phase 3 extracted from the top of the stripping tower is cooled in a condenser 11 to form a condensed mixed liquid phase 5 which is sent to a distillation tower 12, and a crude isocyanate 4 with a low monophenyl ring impurity content after stripping is obtained at the bottom of the stripping tower;
  • a condensed mixed liquid phase 5 composed of single benzene ring impurities, low-boiling point inert organic matter and crude isocyanate is added from the middle of the tower and distilled in the distillation tower, and a stripping agent vapor 6 with a low content of single benzene ring impurities is obtained at the top of the tower, and a refined crude isocyanate 8 is obtained at the bottom of the tower.
  • High-purity single benzene ring impurities 7 are extracted from the tower, and the single benzene ring impurities 7 are recovered as waste liquid; the refined crude isocyanate 8 obtained at the bottom of the tower is recovered into the crude isocyanate product 9, and the low-boiling point inert organic matter gas phase (stripping agent vapor 6) at the top of the tower can be directly used as the stripping steam of the stripping tower 10.
  • the monophenyl ring impurities in the crude isocyanate refer to halogenated monophenyl ring impurities.
  • the crude isocyanate is generally composed of 92wt%-95wt% of dicyclic and polycyclic isocyanates, and the rest are impurities.
  • the low boiling point inert organic matter used includes at least one of carbon tetrachloride, chloroform, dichloromethane, monochloromethane, etc., and the amount of the stripping agent used is 0.01-0.02 Nm 3 /h per ton of crude isocyanate, preferably 0.013-0.017 Nm 3 /h per ton of crude isocyanate.
  • the operating temperature of the stripping tower is 160-220°C, for example, including but not limited to 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, preferably 170-210°C, more preferably 180-200°C; the operating pressure is controlled at 10-100kPa, for example, including but not limited to 10kPa, 20kPa, 30kPa, 40kPa, 50kPa, 60kPa, 70kPa, 80kPa, 90kPa, 100kPa, preferably 30-80kPa, more preferably 50-60kPa.
  • the crude isocyanate is introduced into the inlet pipeline of the liquid distributor at the top of the stripping tower, evenly distributed into the packing of the stripping tower, and forms a thin film on the surface of the packing and flows evenly downward; the steam of the low-boiling inert organic matter is introduced from the lower part of the stripping tower, and is evenly distributed into the stripping tower through the gas distributor and flows evenly upward.
  • the low boiling point inert organic vapor in the filler contacts the crude isocyanate on the surface of the filler, and the monophenyl ring impurities are transferred from the crude isocyanate to the low boiling point organic vapor.
  • the filler can be any filler commonly used in the art, such as annular filler, saddle filler, metal corrugated plate filler, metal wire mesh filler, etc.
  • step 1) low-boiling-point inert organic matter, monophenyl ring impurities and crude isocyanate in the top gas phase of the stripping tower form an organic mixture, wherein the mass percentage of the crude isocyanate is 1-5%, preferably 2-4%; the gas phase of the mixture is cooled in a condenser to form a liquid phase, and then sent to the distillation tower of step 2) for separation, and the cooling temperature of the condenser is controlled at 10-50°C, for example, including but not limited to 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, preferably 20-40°C.
  • the crude isocyanate obtained at the bottom of the stripping tower has a monophenyl ring impurity content of 10-1000 ppm, for example including but not limited to 10 ppm, 30 ppm, 50 ppm, 75 ppm, 100 ppm, 150 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, preferably 100-500 ppm.
  • step 2) the operating temperature of the bottom of the distillation tower is controlled at 220-300°C, for example, including but not limited to 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, preferably 220-260°C; the operating pressure is controlled at 70-150kPa, for example, including but not limited to 70kPa, 80kPa, 90kPa, 100kPa, 110kPa, 120kPa, 130kPa, 140kPa, 150kPa, preferably 80-110kPa, more preferably 80-100kPa.
  • the low-boiling point inert organic vapor obtained at the top of the tower has a single benzene ring impurity content of less than 500 ppm, preferably less than 200 ppm, more preferably less than 150 ppm, for example 100 ppm, 50 ppm, 10 ppm or less, and the organic vapor is directly introduced into the stripping tower of step 1) for use as stripping steam.
  • step 2) the extraction amount of the single benzene ring impurity product obtained in the tower accounts for 3.5%-4.2% of the mass ratio of the tower feed amount, preferably 3.9%-4.1%, and the content of low-boiling inert organic matter in the single benzene ring impurity product obtained in the tower is less than 50000ppm, preferably less than 5000ppm. More preferably, it is lower than 1000ppm, such as 500ppm, 100ppm, 10ppm; the crude isocyanate content is lower than 3%, preferably lower than 2%, such as 1%, 0.5%, 0.1%, 10ppm, and this part of pure product is directly discharged as waste liquid.
  • the crude isocyanate obtained in the bottom of the tower has a single benzene ring impurity content of less than 5%, preferably less than 3%, for example 1%, 100 ppm, 10 ppm or less, and the crude isocyanate obtained by rectification can be directly recycled into the crude isocyanate product for use.
  • the single benzene ring impurities in the crude isocyanate obtained in the bottom of the tower in this step are enriched and concentrated, but since the total flow rate of this part of the recovered crude isocyanate is very small, recycling it into the crude isocyanate product has little effect on the single benzene ring impurity content in the crude isocyanate product.
  • the crude isocyanate loss ratio refers to the ratio of the crude isocyanate that cannot be recovered due to stripping to the crude isocyanate in the feed, specifically, in the embodiments, it is the ratio of the crude isocyanate in the material as waste liquid extracted from the middle of the distillation tower in step 2 to the crude isocyanate in the feed, and in the comparative example, it is the ratio of the crude isocyanate in the material as waste liquid extracted from the top of the stripping tower to the crude isocyanate in the feed.
  • the content of isocyanate is tested by conventional gas chromatography method, which is well known to those skilled in the art.
  • the content of monophenyl ring impurities in the crude isocyanate fed was 850 ppm (mass ratio).
  • the crude isocyanate flowed from the top to the bottom in the filler, and the chloroform vapor flowed from the bottom to the top.
  • the stripping ratio was 0.015 Nm 3 /h per ton of crude isocyanate.
  • the monophenyl ring impurities in the crude isocyanate were stripped and transferred to the gas phase.
  • the operating temperature of the stripping tower was The temperature is 165°C and the operating pressure is 20 kPa.
  • a gaseous mixture with a crude isocyanate content of 1.9% is obtained at the top of the stripping tower, and the mixture is cooled to a liquid phase in a condenser with an operating temperature of 20°C.
  • a crude isocyanate product with a single benzene ring impurity content of 165 ppm is obtained at the bottom of the stripping tower;
  • the condensate obtained from the condenser is added from the middle of the tower and distilled in the distillation tower.
  • the operating temperature of the distillation tower kettle is 255°C and the operating pressure is 75kPa.
  • the chloroform gas phase with low content of single benzene ring impurities is obtained at the top of the distillation tower, wherein the content of single benzene ring impurities is 133ppm, which can be directly used as the stripping steam of the stripping tower; high-purity single benzene ring impurities are extracted from the tower, and the ratio of the extraction amount to the feed amount of the distillation tower is 3.56%, the content of low-boiling inert organic matter is 5200ppm, and the content of crude isocyanate is 1.6%.
  • the extracted single benzene ring impurities are treated as waste liquid; the single benzene ring impurities content in the refined crude isocyanate obtained at the bottom of the tower is 3.2%, which can be directly recycled into the aforementioned crude isocyanate product, and the single benzene ring impurity content in the crude isocyanate product is finally 231ppm.
  • the content of monobenzene ring impurities in the crude isocyanate is 1350ppm (mass ratio).
  • the crude isocyanate flows from the top to the bottom in the filler, and the dichloromethane vapor flows upward from the bottom to the top.
  • the stripping ratio is 0.019Nm3 /h per ton of crude isocyanate.
  • the monobenzene ring impurities in the crude isocyanate are stripped and transferred to the gas phase.
  • the operating temperature of the stripping tower is 205°C and the operating pressure is 75kPa.
  • a gas phase mixture with a crude isocyanate content of 3.6% is obtained at the top of the stripping tower, and the mixture is cooled to a liquid phase in a condenser with an operating temperature of 35°C.
  • a crude isocyanate product with a monobenzene ring impurity content of 542ppm is obtained at the bottom of the stripping tower;
  • the condensate obtained from the condenser is added from the middle of the tower and distilled in the distillation tower.
  • the operating temperature of the distillation tower kettle is 276°C and the operating pressure is 90kPa.
  • Dichloromethane with low content of single benzene ring impurities is obtained at the top of the distillation tower, wherein the content of single benzene ring impurities is 181ppm, which can be directly used as stripping steam for the stripping tower; high-purity single benzene ring impurities are extracted from the tower, and the ratio of the extraction amount to the feed amount of the distillation tower is 4.05%, the content of low-boiling inert organic matter is 658ppm, and the content of crude isocyanate is 2.5%.
  • the extracted single benzene ring impurities are treated as waste liquid; the refined crude isocyanate obtained at the bottom of the tower has a single benzene ring impurity content of 2.8%, which can be directly recycled into the aforementioned crude isocyanate product, and the single benzene ring impurity content in the crude isocyanate product is finally 614ppm.
  • the content of monobenzene ring impurities in the crude isocyanate is 1950ppm (mass ratio).
  • the crude isocyanate flows from the top to the bottom in the filler, and the carbon tetrachloride vapor flows upward from the bottom to the top.
  • the stripping ratio is 0.011Nm3 /h per ton of crude isocyanate.
  • the monobenzene ring impurities in the crude isocyanate are stripped and transferred to the gas phase.
  • the operating temperature of the stripping tower is 195°C and the operating pressure is 55kPa.
  • a gas phase mixture with a crude isocyanate content of 2.2% is obtained at the top of the stripping tower, and the mixture is cooled to a liquid phase in a condenser with an operating temperature of 45°C.
  • a crude isocyanate product with a monobenzene ring impurity content of 741ppm is obtained at the bottom of the stripping tower;
  • the condensate obtained from the condenser is added from the middle of the tower and distilled in the distillation tower.
  • the operating temperature of the distillation tower kettle is 287°C and the operating pressure is 125kPa.
  • the carbon tetrachloride gas phase with low single benzene ring impurity content is obtained at the top of the distillation tower, wherein the single benzene ring impurity content is 436ppm, which can be directly used as the stripping steam of the stripping tower; high purity carbon tetrachloride is extracted from the tower.
  • the ratio of the extracted amount to the feed amount of the distillation tower is 4.08%, the content of low-boiling inert organic matter is 30800 ppm, the content of crude isocyanate is 2.14%, and the extracted single benzene ring impurities are treated as waste liquid; the content of single benzene ring impurities in the refined crude isocyanate obtained at the bottom of the tower is 3.04%, which can be directly recovered into the aforementioned crude isocyanate product, and the final content of single benzene ring impurities in the crude isocyanate product is 804 ppm.
  • the monophenyl ring impurity content in the crude isocyanate is 850 ppm (mass ratio).
  • Nitrogen is used for stripping in a stripping tower with an operating temperature of 165°C and an operating pressure of 20 kPa, and the stripping rate is 0.015 Nm 3 /h per ton of crude isocyanate.
  • the crude isocyanate product obtained at the bottom of the stripping tower has a monophenyl ring impurity content of 568 ppm, and the isocyanate content in the gas phase mixture at the top of the tower is 4.8%.
  • the monophenyl ring impurity content in the crude isocyanate was 1350 ppm (mass ratio). Nitrogen was used for stripping in a stripping tower at an operating temperature of 205°C and an operating pressure of 75 kPa, and the stripping rate was 0.019 Nm 3 /h per ton of crude isocyanate.
  • the crude isocyanate product obtained at the bottom of the stripping tower had a monophenyl ring impurity content of 864 ppm, and the isocyanate content in the gas phase mixture at the top of the tower was 5.6%.
  • the monophenyl ring impurity content in the crude isocyanate was 1950 ppm (mass ratio). Nitrogen was used for stripping in a stripping tower with an operating temperature of 195°C and an operating pressure of 20 kPa. The stripping rate was 0.015 Nm 3 /h per ton of crude isocyanate.
  • the crude isocyanate product obtained at the bottom of the stripping tower had a monophenyl ring impurity content of 1470 ppm.
  • the isocyanate content in the composition is 2.8%.
  • the content of monobenzene ring impurities in the crude isocyanate fed is 850ppm (mass ratio).
  • the crude isocyanate flows from the top to the bottom in the filler, and the chloroform vapor flows upward from the bottom to the top.
  • the stripping ratio is 0.03Nm3 /h per ton of crude isocyanate.
  • the monobenzene ring impurities in the crude isocyanate are stripped and transferred to the gas phase.
  • the operating temperature of the stripping tower is 165°C and the operating pressure is 20kPa.
  • a gas phase mixture with a crude isocyanate content of 1.8% is obtained at the top of the stripping tower, and a crude isocyanate product with a monobenzene ring impurity content of 128ppm is obtained at the bottom of the stripping tower.
  • the content of monobenzene ring impurities in the crude isocyanate fed is 850ppm (mass ratio).
  • the crude isocyanate flows from the top to the bottom in the filler, and the chloroform vapor flows upward from the bottom to the top.
  • the stripping ratio is 0.015Nm3 /h per ton of crude isocyanate.
  • the monobenzene ring impurities in the crude isocyanate are stripped and transferred to the gas phase.
  • the operating temperature of the stripping tower is 140°C and the operating pressure is 20kPa.
  • a gas phase mixture with a crude isocyanate content of 0.56% is obtained at the top of the stripping tower, and a crude isocyanate product with a monobenzene ring impurity content of 479ppm is obtained at the bottom of the stripping tower;
  • the single benzene ring impurity content removal process in this case has a good removal effect on the single benzene ring impurity content compared to the conventional nitrogen stripping process, and the loss of crude isocyanate is greatly reduced, which has good implementation effect and significance.
  • the proportion of MDI content in the gas phase at the top of the stripping tower to the feed MDI content may increase significantly, resulting in a significant reduction in economic efficiency, or a significant reduction in the removal rate of single benzene ring impurities in the crude isocyanate at the bottom of the stripping tower.

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Abstract

本发明涉及一种低单苯环类杂质含量的粗异氰酸酯的生产工艺，包括以下步骤：1)以低沸点的惰性有机物作为汽提剂，在汽提塔中，对粗异氰酸酯进行汽提来脱除单苯环类杂质组分，得到低单苯环类杂质含量的粗异氰酸酯产品；2)通过精馏将汽提塔顶部采出的单苯环类杂质组分/汽提剂与粗异氰酸酯进行分离，塔底将高纯度的粗异氰酸酯回收，塔顶形成的汽提剂蒸汽可直接通入汽提塔底部进行汽提，塔中采出浓缩后的单苯环类杂质作为废液处理。本发明的生产工艺有效降低了单苯环类杂质组分与粗异氰酸酯的分离难度，实现了高纯度粗异氰酸酯的简单回收，且粗异氰酸酯的损失量大大降低。

Description

一种低单苯环类杂质含量的粗异氰酸酯的生产工艺 技术领域
本发明涉及异氰酸酯生产技术领域，具体涉及一种低单苯环类杂质含量的粗异氰酸酯的生产工艺。
背景技术
异氰酸酯广泛应用于鞋底原液、聚氨酯泡沫、保温材料、人造皮革等制品的合成与制作。异氰酸酯主要采用光气法制备，相应的胺类与惰性溶剂混合后再与光气进行充分混合进行光气化反应，得到光化反应液，光化反应液经过光气脱除、溶剂脱除后得到粗异氰酸酯。在生产多亚甲基多苯基多异氰酸酯过程中，由于原料胺中通常含有少量的单苯环胺类物质，导致生产得到的粗异氰酸酯中含有单苯环异氰酸酯或其衍生物，单苯环异氰酸酯或其衍生物具有较低的沸点及较低的反应活性，在后续粗异氰酸酯的分离过程中易留存于产品中，导致多亚甲基多苯基多异氰酸酯产品中含有一定量(通常为800-3000ppm)的单苯环异氰酸酯或其衍生物，可能对使用人员的健康产生危害。
CN107652208A公开了一种从光气化反应得到的异氰酸酯产物中脱除溶剂的方法和系统，通过采用不同形式的塔内件的塔对异氰酸酯产物中的溶剂进行脱除。其中采用散堆填料塔对异氰酸酯产物中的溶剂组分进行脱除。该专利中没有对该过程中的异氰酸酯产物中的单苯环异氰酸酯及衍生物的脱除效果进行描述，且汽提过程会导致部分异氰酸酯损失。
CN108586706A公开了一种异氰酸酯的提纯方法，具体地涉及低 氯含量的异氰酸酯的制备方法。在常压下通入惰性气体汽提脱除异氰酸酯中的氯代衍生物及溶剂。该专利提供采用热氮气对粗异氰酸酯进行汽提脱除轻组分的工艺，但是由于单苯环杂质组分的含量非常低，如果需要彻底脱除单苯环杂质组分，在汽提过程中气相会夹带较多量的粗异氰酸酯，该部分异氰酸酯与多苯环杂质组分的混合物需要被循环回系统以降低粗异氰酸酯的损耗，导致单苯环杂质组分在系统内累积并形成动态平衡，限制粗异氰酸酯中单苯环杂质组分的彻底脱除。
单苯环类杂质作为一种轻组分，在后续工序粗异氰酸酯的分离过程中，存在于塔顶轻组分及塔中的纯异氰酸酯产品中，导致塔顶产生的废液需要进一步处理，塔中的纯异氰酸酯产品的质量降低，影响纯异氰酸酯的反应活性。
由于这种单苯环类杂质在粗异氰酸酯中的含量较低，采用传统的惰性气体汽提工艺存在单苯环杂质与粗异氰酸酯分离度较低，需要采用大量的惰性气体，在较高的温度下进行杂质脱除，该过程中会有大量的粗异氰酸酯与单苯环杂质共同被脱除，损失的粗异氰酸酯占总异氰酸酯进料的比例为0.15％-0.3％，造成了巨大的经济损失。
因此，需要一种更高效、更经济的技术方案来脱除粗异氰酸酯中的单苯环杂质组分，进而提升产品质量。
发明内容
本发明的目的是提供一种低单苯环类杂质含量的粗异氰酸酯的生产工艺，可有效降低单苯环类杂质组分与粗异氰酸酯的分离难度，实现高纯度粗异氰酸酯的简单回收，且粗异氰酸酯的损失量大大降低。
为了达到以上目的，本发明采用如下技术方案：
一种低单苯环类杂质含量的粗异氰酸酯的生产工艺，包括以下步骤：
1)以低沸点的惰性有机物作为汽提剂，在汽提塔中，对粗异氰酸酯进行汽提来脱除单苯环类杂质组分，汽提塔塔底得到低单苯环类杂质含量的粗异氰酸酯产品，汽提塔塔顶得到含有少量粗异氰酸酯的单苯环类杂质组分和汽提剂；
2)汽提塔顶部采出的单苯环类杂质组分、汽提剂与粗异氰酸酯采用精馏塔进行分离，精馏塔塔底得到高纯度的粗异氰酸酯，塔顶采出汽提剂蒸汽，塔中采出浓缩后的单苯环类杂质。
在一个具体的实施方案中，所述粗异氰酸酯中的单苯环类杂质为卤代单苯环类物质，选自一氯代苯基异氰酸酯、二氯代苯基异氰酸酯、三氯代苯基异氰酸酯、一溴代苯基异氰酸酯、二溴代苯基异氰酸酯、三溴代苯基异氰酸酯中的至少任一种；优选地，所述单苯环类杂质在粗异氰酸酯中的含量为800-2000ppm。
在一个具体的实施方案中，步骤1)中所述的低沸点的惰性有机物选自四氯化碳、三氯甲烷、二氯甲烷、一氯甲烷中的至少任一种；优选地，所述汽提剂的用量比例为0.01-0.02Nm3/h每吨粗异氰酸酯，优选为0.013-0.017Nm3/h每吨粗异氰酸酯。
在一个具体的实施方案中，步骤1)中所述汽提塔的操作温度在160-220℃，优选170-210℃，更优选180-200℃；操作压力控制在10-100kPa，优选30-80kPa，更优选50-60kPa。
在一个具体的实施方案中，步骤1)中所述汽提塔的顶部气相中的异氰酸酯的质量含量为1-5％，优选为2-4％；优选地，步骤1)中所述汽提塔的底部得到的粗异氰酸酯中，单苯环类杂质含量为10-1000ppm，优选为100-500ppm。
在一个具体的实施方案中，步骤2)中汽提塔顶部采出的混合物气相在一个冷凝器中被冷却形成液相，换热器的冷却温度控制在10-50℃，优选20-40℃。
在一个具体的实施方案中，步骤2)中精馏塔的塔釜温度在220-300℃，优选220-260℃；操作压力控制在70-150kPa，优选80-110kPa。
在一个具体的实施方案中，步骤2)中精馏塔塔顶得到的汽提剂蒸汽中，单苯环类杂质含量低于500ppm，优选低于200ppm，更优选低于150ppm；优选地，精馏塔塔顶采出的汽提剂蒸汽直接被引入到步骤1)汽提塔中作为汽提蒸汽使用。
在一个具体的实施方案中，步骤2)中塔中采出的单苯环类杂质产品的采出量占塔进料量的质量比例为3.5％-4.2％，优选3.9％-4.1％，采出产品中低沸点的惰性有机物含量低于50000ppm，优选低于5000ppm；粗异氰酸酯含量低于3％，优选低于2％；优选地，塔中采出浓缩后的单苯环类杂质纯品直接作为废液进行处理。
在一个具体的实施方案中，步骤2)中精馏塔塔釜得到的粗异氰酸酯中，单苯环类杂质的质量含量低于5％，优选低于3％；优选地，精馏得到的粗异氰酸酯可直接回收至粗异氰酸酯产品中使用。
与现有技术相比，本发明具有以下有益效果：
本发明的生产工艺采用低沸点的惰性有机物作为汽提气，在汽提塔中，对粗异氰酸酯进行汽提来脱除单苯环类杂质组分，被脱除的单苯环类杂质组分、汽提用的低沸点有机物及被夹带的粗异氰酸酯在汽提塔顶部的冷凝器中被冷凝形成混合物，再经精馏塔将单苯环类杂质组分/汽提剂与粗异氰酸酯在塔底处分离，将高纯度的粗异氰酸酯回收，将汽提剂与单苯环类杂质在塔上部进行分离，形成的汽提剂蒸汽可直接通入汽提塔底部进行汽提，塔中采出浓缩后的单苯环类杂质作为废液处理。
本发明汽提用的低沸点的惰性有机物对于单苯环杂质具有较好的溶解度，在单苯环类杂质及异氰酸酯形成的混合物中，可起到提高单苯环类杂质组分与粗异氰酸酯的分离度的作用，有效降低了单苯环类杂质组分与粗异氰酸酯的分离难度，实现高纯度的粗异氰酸酯的回收；低沸点惰性汽提剂与单苯环类杂质组分可通过精馏的形式回收惰性汽提剂，通过控制精馏塔的操作条件使得精馏塔顶得到较高纯度的惰性汽提剂蒸汽直接采出，得到的惰性汽提剂蒸汽压力较为适宜，可直接用于粗异氰酸酯的汽提，形成惰性气提剂在系统内的循环使用。
本发明的生产工艺简单高效，特别适用于工业化应用。
附图说明
图1为本发明一种低单苯环类杂质含量的粗异氰酸酯的生产工艺流程示意图。
其中，1为粗异氰酸酯原料；2汽提剂；3混合气相；4经过汽提后的低单苯环类杂质含量的粗异氰酸酯；5混合液相；6汽提剂蒸 汽；7单苯环类杂质；8粗异氰酸酯；9最终粗异氰酸酯产品；10汽提塔；11冷凝器；12精馏塔。
具体实施方式
为了更好理解本发明的技术方案，下面的实施例将对本发明所提供的方法予以进一步的说明，但本发明不限于所列出的实施例，还应包括在本发明的权利要求范围内其他任何公知的改变。
如图1所示，一种低单苯环类杂质含量的粗异氰酸酯的生产工艺，包括以下步骤：
1)在汽提塔10中，粗异氰酸酯原料1由汽提塔10塔顶部自上而下流动，低沸点的惰性有机物蒸汽作为汽提剂2自下而上向上流动，粗异氰酸酯中的单苯环类杂质被汽提并转移至气相中；汽提塔顶部采出的混合气相3在冷凝器11中被冷却形成经过冷凝后的混合液相5送至精馏塔12，汽提塔底部得到经过汽提后的低单苯环类杂质含量的粗异氰酸酯4；
2)在精馏塔12中，单苯环类杂质、低沸点的惰性有机物及粗异氰酸酯组成的经过冷凝后的混合液相5由塔中部加入，并在精馏塔中进行精馏，塔顶得到低单苯环类杂质含量的汽提剂蒸汽6，塔底得到精制的粗异氰酸酯8，塔中采出高纯度的单苯环类杂质7，单苯环类杂质7作为废液回收处理；塔底得到的精制的粗异氰酸酯8回收至粗异氰酸酯产品9中，塔顶的低沸点惰性有机物气相(汽提剂蒸汽6)可直接作为汽提塔10的汽提蒸汽使用。
步骤1)中，粗异氰酸酯中的单苯环类杂质是指卤代单苯环类物 质，包括一氯代苯基异氰酸酯、二氯代苯基异氰酸酯、三氯代苯基异氰酸酯、一溴代苯基异氰酸酯、二溴代苯基异氰酸酯、三溴代苯基异氰酸酯等中的至少任一种，其含量通常为800-2000ppm，例如800ppm、1000ppm、1500ppm、1800ppm。其中，粗异氰酸酯的组成通常为二环及多环异氰酸酯92wt％-95wt％，其它为杂质。
步骤1)中，所用的低沸点的惰性有机物包括四氯化碳、三氯甲烷、二氯甲烷、一氯甲烷等中的至少任一种，汽提剂的用量比例为0.01-0.02Nm3/h每吨粗异氰酸酯，优选0.013-0.017Nm3/h每吨粗异氰酸酯。
步骤1)中，汽提塔的操作温度在160-220℃，例如包括但不限于160℃、170℃、180℃、190℃、200℃、210℃、220℃，优选为170-210℃，更优选为180-200℃；操作压力控制在10-100kPa，例如包括但不限于10kPa、20kPa、30kPa、40kPa、50kPa、60kPa、70kPa、80kPa、90kPa、100kPa，优选为30-80kPa，更优选为50-60kPa。一些具体实施方式中，粗异氰酸酯在汽提塔的顶部的液体分布器入口管线中引入，均匀地分布到汽提塔的填料中，在填料表面上形成薄膜均匀向下流动；低沸点的惰性有机物的蒸汽由汽提塔的下部引入，通过气体分布器均匀地分布到汽提塔中均匀向上流动。在填料中低沸点惰性有机物蒸汽与粗异氰酸酯在填料表面接触，单苯环类杂质由粗异氰酸酯中转移至低沸点有机物蒸汽中。其中的填料为本领域常用的填料即可，例如可以为环形填料、鞍型填料、金属波纹板填料、金属丝网填料等。
步骤1)中，汽提塔的顶部气相中的低沸点惰性有机物、单苯环类杂质及粗异氰酸酯形成有机混合物，其中，粗异氰酸酯的质量百分含量为1-5％，优选为2-4％；该混合物气相在一个冷凝器中被冷却形成液相，随后被送至步骤2)的精馏塔进行分离，冷凝器的冷却温度控制在10-50℃，例如包括但不限于15℃、20℃、25℃、30℃、35℃、40℃、45℃、50℃，优选为20-40℃。
步骤1)中，汽提塔的底部得到的粗异氰酸酯中，单苯环类杂质含量为10-1000ppm，例如包括但不限于10ppm、30ppm、50ppm、75ppm、100ppm、150ppm、200ppm、300ppm、400ppm、500ppm、600ppm、700ppm、800ppm、900ppm、1000ppm，优选为100-500ppm。
步骤2)中，精馏塔的塔釜操作温度控制在220-300℃，例如包括但不限于220℃、230℃、240℃、250℃、260℃、270℃、280℃、290℃、300℃，优选为220-260℃；操作压力控制在70-150kPa，例如包括但不限于70kPa、80kPa、90kPa、100kPa、110kPa、120kPa、130kPa、140kPa、150kPa，优选80-110kPa，进一步优选为80-100kPa。
步骤2)中，塔顶得到的低沸点惰性有机物蒸汽中，单苯环杂质含量为低于500ppm，优选低于200ppm，更优选低于150ppm，例如100ppm、50ppm、10ppm或更低，该有机物蒸汽直接被引入步骤1)汽提塔中作为汽提蒸汽使用。
步骤2)中，塔中得到的单苯环类杂质产品的采出量占塔进料量质量比的3.5％-4.2％，优选3.9％-4.1％，塔中得到的单苯环类杂质产品中，低沸点惰性有机物含量低于50000ppm，优选低于5000ppm， 更优选低于1000ppm，例如500ppm、100ppm、10ppm；粗异氰酸酯含量低于3％，优选低于2％，例如1％、0.5％、0.1％、10ppm，该部分纯品直接作为废液进行排放。
步骤2)中，塔釜得到的粗异氰酸酯中，单苯环类杂质含量为低于5％，优选低于3％，例如1％、100ppm、10ppm或更低，该通过精馏得到的粗异氰酸酯回收可直接回收至粗异氰酸酯产品中使用。该步骤塔釜中得到的粗异氰酸酯中的单苯环杂质存在富集浓缩的情况，但由于这部分回收的粗异氰酸酯总流量非常小，回收至粗异氰酸酯产品中对粗异氰酸酯产品中的单苯环杂质含量影响很小。
下面用实施例对本发明做进一步说明，但本发明不受其限制。
实施例及对比例中，粗异氰酸酯损失量比例是指因汽提导致的无法回收的粗异氰酸酯占进料粗异氰酸酯的比例，具体地，实施例中为步骤2精馏塔中部采出的作为废液的物料中的粗异氰酸酯占进料粗异氰酸酯的比例，对比例中为汽提塔顶部采出的作为废液的物料中的粗异氰酸酯占进料粗异氰酸酯的比例。其中，异氰酸酯的含量采用常规的气相色谱方法测试得到，这是本领域技术人员所熟知的。
实施例1
进料的粗异氰酸酯中的单苯环类杂质含量为850ppm(质量比)。在汽提塔中，粗异氰酸酯在填料中由顶部自上而下流动，三氯甲烷蒸汽自下而上向上流动，汽提比例为0.015Nm3/h每吨粗异氰酸酯，粗异氰酸酯中的单苯环类杂质被汽提并转移至气相中，汽提塔的操作温 度为165℃，操作压力为20kPa。汽提塔顶部得到粗异氰酸酯含量为1.9％的气相混合物，该混合物在操作温度为20℃的冷凝器中被冷却为液相。汽提塔底部得到单苯环类杂质含量为165ppm的粗异氰酸酯产品；
在精馏塔中，由冷凝器得到的冷凝液由塔中部加入，并在精馏塔中进行精馏，精馏塔塔釜操作温度为255℃，操作压力为75kPa。精馏塔顶得到低单苯环类杂质含量的三氯甲烷气相，其中单苯环杂质含量为133ppm，可直接作为汽提塔的汽提蒸汽使用；塔中采出高纯度的单苯环类杂质，采出量与精馏塔进料量的比例为3.56％，低沸点惰性有机物含量为5200ppm，粗异氰酸酯含量为1.6％，采出的单苯环类杂质作为废液处理；塔底得到的精制的粗异氰酸酯中单苯环杂质含量为3.2％，可直接回收至前述粗异氰酸酯产品中，粗异氰酸酯产品中的单苯环杂质含量最终为231ppm。
实施例2
本例中粗异氰酸酯中的单苯环类杂质含量为1350ppm(质量比)。在汽提塔中，粗异氰酸酯在填料中由顶部自上而下流动，二氯甲烷蒸汽自下而上向上流动，汽提比例为0.019Nm3/h每吨粗异氰酸酯，粗异氰酸酯中的单苯环类杂质被汽提并转移至气相中，汽提塔的操作温度为205℃，操作压力为75kPa。汽提塔顶部得到粗异氰酸酯含量为3.6％的气相混合物，该混合物在操作温度为35℃的冷凝器中被冷却为液相。汽提塔底部得到单苯环类杂质含量为542ppm的粗异氰酸酯产品；
在精馏塔中，由冷凝器得到的冷凝液由塔中部加入，并在精馏塔中进行精馏，精馏塔塔釜操作温度为276℃，操作压力为90kPa。精馏塔顶得到低单苯环类杂质含量的二氯甲烷，其中单苯环杂质含量为181ppm，可直接作为汽提塔的汽提蒸汽使用；塔中采出高纯度的单苯环类杂质，采出量与精馏塔进料量的比例为4.05％，低沸点惰性有机物含量为658ppm，粗异氰酸酯含量为2.5％，采出的单苯环类杂质作为废液处理；塔底得到的精制的粗异氰酸酯中单苯环杂质含量为2.8％，可直接回收至前述粗异氰酸酯产品中，粗异氰酸酯产品中的单苯环杂质含量最终为614ppm。
实施例3
本例中粗异氰酸酯中的单苯环类杂质含量为1950ppm(质量比)。在汽提塔中，粗异氰酸酯在填料中由顶部自上而下流动，四氯化碳蒸汽自下而上向上流动，汽提比例为0.011Nm3/h每吨粗异氰酸酯，粗异氰酸酯中的单苯环类杂质被汽提并转移至气相中，汽提塔的操作温度为195℃，操作压力为55kPa。汽提塔顶部得到粗异氰酸酯含量为2.2％的气相混合物，该混合物在操作温度为45℃的冷凝器中被冷却为液相。汽提塔底部得到单苯环类杂质含量为741ppm的粗异氰酸酯产品；
在精馏塔中，由冷凝器得到的冷凝液由塔中部加入，并在精馏塔中进行精馏，精馏塔塔釜操作温度为287℃，操作压力为125kPa。精馏塔顶得到低单苯环类杂质含量的四氯化碳气相，其中单苯环杂质含量为436ppm，可直接作为汽提塔的汽提蒸汽使用；塔中采出高纯度 的单苯环类杂质，采出量与精馏塔进料量的比例为4.08％，低沸点惰性有机物含量为30800ppm，粗异氰酸酯含量为2.14％，采出的单苯环类杂质作为废液处理；塔底得到的精制的粗异氰酸酯中单苯环杂质含量为3.04％，可直接回收至前述粗异氰酸酯产品中，粗异氰酸酯产品中的单苯环杂质含量最终为804ppm。
对比例1
本例中粗异氰酸酯中的单苯环类杂质含量为850ppm(质量比)。在操作温度为165℃，操作压力为20kPa的汽提塔中采用氮气进行汽提，汽提比例为0.015Nm3/h每吨粗异氰酸酯。汽提塔底得到的粗异氰酸酯产品中，单苯环类杂质含量为568ppm，塔顶气相混合物中异氰酸酯的含量为4.8％。
对比例2
本例中粗异氰酸酯中的单苯环类杂质含量为1350ppm(质量比)。在操作温度为205℃，操作压力为75kPa的汽提塔中采用氮气进行汽提，汽提比例为0.019Nm3/h每吨粗异氰酸酯。汽提塔底得到的粗异氰酸酯产品中，单苯环类杂质含量为864ppm，塔顶气相混合物中异氰酸酯的含量为5.6％。
对比例3
本例中粗异氰酸酯中的单苯环类杂质含量为1950ppm(质量比)。在操作温度为195℃，操作压力为20kPa的汽提塔中采用氮气进行汽提，汽提比例为0.015Nm3/h每吨粗异氰酸酯。汽提塔底得到的粗异氰酸酯产品中，单苯环类杂质含量为1470ppm，塔顶气相混 合物中异氰酸酯的含量为2.8％。
对比例4
进料的粗异氰酸酯中的单苯环类杂质含量为850ppm(质量比)。在汽提塔中，粗异氰酸酯在填料中由顶部自上而下流动，三氯甲烷蒸汽自下而上向上流动，汽提比例为0.03Nm3/h每吨粗异氰酸酯，粗异氰酸酯中的单苯环类杂质被汽提并转移至气相中，汽提塔的操作温度为165℃，操作压力为20kPa。汽提塔顶部得到粗异氰酸酯含量为1.8％的气相混合物，汽提塔底部得到单苯环类杂质含量为128ppm的粗异氰酸酯产品。
对比例5
进料的粗异氰酸酯中的单苯环类杂质含量为850ppm(质量比)。在汽提塔中，粗异氰酸酯在填料中由顶部自上而下流动，三氯甲烷蒸汽自下而上向上流动，汽提比例为0.015Nm3/h每吨粗异氰酸酯，粗异氰酸酯中的单苯环类杂质被汽提并转移至气相中，汽提塔的操作温度为140℃，操作压力为20kPa。汽提塔顶部得到粗异氰酸酯含量为0.56％的气相混合物，汽提塔底部得到单苯环类杂质含量为479ppm的粗异氰酸酯产品；
表1实施例1-3及对比例1-3效果

表2实施例1及对比例4-5效果
从上表可以看出，采用本案中的单苯环杂质含量脱除工艺，对比常规的氮气汽提工艺，对于单苯环杂质含量具有良好的脱除效果，且粗异氰酸酯的损失量大大降低，具有良好的实施效果及意义。偏离本案中的汽提塔操作工艺参数时，可能导致汽提塔顶部气相中MDI含量占进料MDI含量的比例大幅提高，导致经济性大幅降低，或汽提塔底部粗异氰酸酯中的单苯环类杂质脱除率显著降低的后果。
尽管本发明的内容已经通过上述优选实施例作了详细介绍，但应当认识到上述的描述不应被认为是对本发明的限制。本领域技术人员可以理解，在本说明书的教导之下，可对本发明做出一些修改或调整。这些修改或调整也应当在本发明权利要求所限定的范围之内。

Claims (10)

  1. 一种低单苯环类杂质含量的粗异氰酸酯的生产工艺，其特征在于，包括以下步骤：
    1)以低沸点的惰性有机物作为汽提剂，在汽提塔中，对粗异氰酸酯进行汽提来脱除单苯环类杂质组分，汽提塔塔底得到低单苯环类杂质含量的粗异氰酸酯产品，汽提塔塔顶得到含有少量粗异氰酸酯的单苯环类杂质组分和汽提剂；
    2)汽提塔顶部采出的单苯环类杂质组分、汽提剂与粗异氰酸酯采用精馏塔进行分离，精馏塔塔底得到高纯度的粗异氰酸酯，塔顶采出汽提剂蒸汽，塔中采出浓缩后的单苯环类杂质。
  2. 根据权利要求1所述的生产工艺，其特征在于，所述粗异氰酸酯中的单苯环类杂质为卤代单苯环类物质，选自一氯代苯基异氰酸酯、二氯代苯基异氰酸酯、三氯代苯基异氰酸酯、一溴代苯基异氰酸酯、二溴代苯基异氰酸酯、三溴代苯基异氰酸酯中的至少任一种；优选地，所述单苯环类杂质在粗异氰酸酯中的含量为800-2000ppm。
  3. 根据权利要求1或2所述的生产工艺，其特征在于，步骤1)中所述的低沸点的惰性有机物选自四氯化碳、三氯甲烷、二氯甲烷、一氯甲烷中的至少任一种；优选地，所述汽提剂的用量比例为0.01-0.02Nm3/h每吨粗异氰酸酯，优选为0.013-0.017Nm3/h每吨粗异氰酸酯。
  4. 根据权利要求1-3任一项所述的生产工艺，其特征在于，步骤1)中所述汽提塔的操作温度在160-220℃，优选170-210℃，更优选 180-200℃；操作压力控制在10-100kPa，优选30-80kPa，更优选50-60kPa。
  5. 根据权利要求1-4任一项所述的生产工艺，其特征在于，步骤1)中所述汽提塔的顶部气相中的异氰酸酯的质量含量为1-5％，优选为2-4％；优选地，步骤1)中所述汽提塔的底部得到的粗异氰酸酯中，单苯环类杂质含量为10-1000ppm，优选为100-500ppm。
  6. 根据权利要求1-5任一项所述的生产工艺，其特征在于，步骤2)中汽提塔顶部采出的混合物气相在一个冷凝器中被冷却形成液相，换热器的冷却温度控制在10-50℃，优选20-40℃；
    优选地，所述汽提塔顶部采出的所述混合物气相在所述冷凝器中被冷却形成所述液相后，再送入所述精馏塔中进行分离。
  7. 根据权利要求1-6任一项所述的生产工艺，其特征在于，步骤2)中精馏塔的塔釜温度在220-300℃，优选220-260℃；操作压力控制在70-150kPa，优选80-110kPa。
  8. 根据权利要求1-7任一项所述的生产工艺，其特征在于，步骤2)中精馏塔塔顶得到的汽提剂蒸汽中，单苯环类杂质含量低于500ppm，优选低于200ppm，更优选低于150ppm；优选地，精馏塔塔顶采出的汽提剂蒸汽直接被引入到步骤1)汽提塔中作为汽提蒸汽使用。
  9. 根据权利要求1-8任一项所述的生产工艺，其特征在于，步骤2)中塔中采出的单苯环类杂质产品的采出量占塔进料量的质量比例为3.5％-4.2％，优选3.9％-4.1％，采出产品中低沸点的惰性有机物含 量低于50000ppm，优选低于5000ppm；粗异氰酸酯含量低于3％，优选低于2％；优选地，塔中采出浓缩后的单苯环类杂质纯品直接作为废液进行处理。
  10. 根据权利要求1-9任一项所述的生产工艺，其特征在于，步骤2)中精馏塔塔釜得到的粗异氰酸酯中，单苯环类杂质的质量含量低于5％，优选低于3％；优选地，精馏得到的粗异氰酸酯可直接回收至粗异氰酸酯产品中使用。
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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DD288599A5 (de) * 1989-10-24 1991-04-04 Veb Synthesewerk Schwarzheide,De Reinigungsverfahren organischer isocyanate von chlorhaltigen verbindungen
DD288598A5 (de) * 1989-10-24 1991-04-04 Veb Synthesewerk Schwarzheide,De Verfahren zur reinigung organischer isocyanate von chlorhaltigen verbindungen
CN1729165A (zh) * 2002-12-19 2006-02-01 巴斯福股份公司 异氰酸酯的提纯方法
CN101302174A (zh) * 2006-05-13 2008-11-12 拜尔材料科学股份公司 生产异氰酸酯的方法
CN101514172A (zh) * 2008-02-19 2009-08-26 拜尔材料科学股份公司 制备异氰酸酯的方法
CN107935889A (zh) * 2017-11-29 2018-04-20 万华化学集团股份有限公司 一种单异氰酸酯的制备方法及系统
CN108348889A (zh) * 2015-09-24 2018-07-31 科思创德国股份有限公司 制备异氰酸酯的方法
CN110396057A (zh) * 2019-07-16 2019-11-01 万华化学（宁波）有限公司 一种制备低氯含量的异氰酸酯的方法
CN114920668A (zh) * 2022-05-13 2022-08-19 万华化学集团股份有限公司 一种制备低氯代杂质异氰酸酯的方法

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DD288599A5 (de) * 1989-10-24 1991-04-04 Veb Synthesewerk Schwarzheide,De Reinigungsverfahren organischer isocyanate von chlorhaltigen verbindungen
DD288598A5 (de) * 1989-10-24 1991-04-04 Veb Synthesewerk Schwarzheide,De Verfahren zur reinigung organischer isocyanate von chlorhaltigen verbindungen
CN1729165A (zh) * 2002-12-19 2006-02-01 巴斯福股份公司 异氰酸酯的提纯方法
CN101302174A (zh) * 2006-05-13 2008-11-12 拜尔材料科学股份公司 生产异氰酸酯的方法
CN101514172A (zh) * 2008-02-19 2009-08-26 拜尔材料科学股份公司 制备异氰酸酯的方法
CN108348889A (zh) * 2015-09-24 2018-07-31 科思创德国股份有限公司 制备异氰酸酯的方法
CN107935889A (zh) * 2017-11-29 2018-04-20 万华化学集团股份有限公司 一种单异氰酸酯的制备方法及系统
CN110396057A (zh) * 2019-07-16 2019-11-01 万华化学（宁波）有限公司 一种制备低氯含量的异氰酸酯的方法
CN114920668A (zh) * 2022-05-13 2022-08-19 万华化学集团股份有限公司 一种制备低氯代杂质异氰酸酯的方法

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