Phosgenation reactor and method for preparing isocyanate monomer by using phosgenation reactor

A reactor and phosgenation technology, applied in chemical instruments and methods, chemical/physical/physicochemical fixed reactors, preparation of organic compounds, etc., can solve the problems of reduced yield, internal leakage blockage, high overall energy consumption, etc. problems, to avoid incomplete amine reaction, reduce contact opportunities, and improve the quality of salt formation

Active Publication Date: 2018-05-29
WANHUA CHEM GRP
5 Cites 11 Cited by

AI-Extracted Technical Summary

Problems solved by technology

However, amines with high melting points generally have poor solubility in the above solvents, resulting in lower reaction concentrations
In addition, some isocyanate polymers and chlorinated by-products will be produced during the reaction, which will not only reduce the yield of the product, but also increase the difficulty of product purification and increase production costs.
[0003] U.S. Patent US2015246873 (A1) provides a method for preparing isocyanate by liquid phase method. High melting point isocyanate is prepared by cold and hot phosgenation. It uses a dynamic mixer to mix amine and solvent to form a suspension and control the particle size. , strengthen the dispersion, thereby reducing the occurrence of side reactions and increasing the yield, but the rapid mixing of solid or liquid suspensions is more difficult, and the minimization of by-products cannot be guaranteed
[0004] Chinese patent CN101638372A uses salt-forming phosgenation to prepare p-phenylene diisocyanate, but its hydrochloric acid needs to be specially prepared, and when forming a salt, it is necessary to dissolve all the amine in a solvent and then pass in hydrogen chloride gas, which can easily cause the amine to be wrapped by hydrochloride , reducing the yield
However, in order to solve the clogging problem and enhance the mixing effect in the process of application, the process needs to be operated at an extremely low concentration of xylylenediamine hydrochloride, and the overall energy consumption is relatively high.
[0006] In the Chinese patent CN102070491A, a centrifugal device is used to concentrate the low-concentration hydrochlor...
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Abstract

The invention discloses a phosgenation reactor and a method for preparing an isocyanate monomer by using the phosgenation reactor. The phosgenation reactor comprises an inner material inlet pipe, an outer material inlet pipe, a mechanical stirring rotation shaft, a rotation area and a kettle body, wherein the rotation area comprises a support structure, a rotation area filler block, an upper material outlet device and a lower material outlet device, the inner material inlet pipe and the outer material inlet pipe are coaxially arranged from inside to outside, the upper material outlet device and the lower material outlet device are arranged in parallel, are connected through the support structure, and are respectively communicated to the outer material inlet pipe and the inner material inlet pipe, the rotation area filler block is filled between the upper material outlet device and the lower material outlet device, the upper material outlet device is connected to the mechanical stirringrotation shaft, and the kettle body is provided with a gas phase material outlet, a liquid phase material outlet, a gas phase material inlet and a liquid phase material inlet. According to the present invention, by pre-treating the hydrochloride solution in the reactor, the salt forming concentration and the quality of the hydrochloride solution are improved while the rapid removal of hydrogen chloride gas during the phosgenation is achieved, such that the generation of chlorination by-products is effectively reduced, and the product separation difficulty is reduced.

Application Domain

Isocyanic acid derivatives preparationOrganic compound preparation +2

Technology Topic

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  • Phosgenation reactor and method for preparing isocyanate monomer by using phosgenation reactor

Examples

  • Experimental program(3)
  • Comparison scheme(1)

Example Embodiment

[0041] Example 1
[0042] The volume of the phosgenation reactor is 800L, and the discharger is perpendicular to the feed pipe. The ratio of the distance between the lower surface of the upper discharger and the upper surface of the lower discharger to the height of the reactor is 1:6, the upper and lower dischargers are of hollow cylindrical structure, and the lower surface of the upper discharger 10 The upper surface of the lower discharger 6 and the lower discharger 6 are evenly distributed with circular outlet holes, the opening rates are 60% and 70%, respectively, the discharger diameter is 70% of the reactor diameter, and the height of the discharger and the diameter of the discharger The ratio is 1:20, the height of the packing block 8 in the rotating zone and the distance between the lower surface of the upper discharger and the upper surface of the lower discharger is 1:1. The filler is a wire mesh filler filled in a regular manner. The inner diameter of the outer feed pipe 2 is 1.3 times the inner diameter of the inner feed pipe 1.
[0043] The salt-forming reactor has a volume of 800L, in which 180Kg of o-dichlorobenzene is added as the reaction solvent in advance, the stirring is turned on, the temperature is controlled to 130°C, and the hydrogen chloride compressed gas is 50m 3 /h through the premixer into the salt formation reactor. After stirring for 10 minutes, the mixture of 1,3-cyclohexanedimethylamine and o-dichlorobenzene (amine concentration 28wt%) is preheated to 120°C , At a flow rate of 80Kg/h, enter the salt-forming reactor and react with hydrogen chloride through the mixer. After 4 hours, the feeding is completed to obtain the amine hydrochloride solution, which is transferred to the phosgenation reactor through the liquid-phase feed port 4. Turn on the stirring at 600 rpm, heat up to 140 ℃, from the gas phase feed port 5 to 10m 3 Hydrogen chloride is introduced at a rate of 1/h. After 30 minutes, the introduction of hydrogen chloride gas is stopped. Nitrogen is introduced from the external feed pipe 2 at a rate of 3 mol/min. The excess hydrogen chloride and nitrogen are discharged through the gas outlet 11, and the salt is discharged after 25 minutes. The acid salt degassing is over, the hydrochloride concentration is 24.5wt%, and the average particle size of the hydrochloride particles is determined to be 23um. The phosgene is introduced through the inner feed pipe 1 at a feed rate of 10mol/min, and at the same time, the outside Feed pipe 2 continues to feed nitrogen at a rate of 3 mol/min. After the solution is clear, stop the phosgene feed to obtain the photochemical reaction liquid, which is discharged from the liquid phase outlet 7 and then dephosgene and solvent are removed. The total amount of chlorinated by-products in the crude product is 890ppm; after separation and purification, 121.4Kg of 1,3-bis(methyl isocyanate)cyclohexane is obtained, and the total chlorine is 29ppm.

Example Embodiment

[0044] Example 2
[0045] The volume of the phosgenation reactor is 800L, and the discharger is perpendicular to the feed pipe. The ratio of the distance between the lower surface of the upper discharger and the upper surface of the lower discharger to the height of the reactor is 1:7, the upper and lower dischargers are of hollow cylindrical structure, and the lower surface of the upper discharger 10 And the upper surface of the lower discharger 6 is evenly distributed with diamond-shaped outlet holes, the opening rates are 70% and 55%, respectively, the diameter of the discharger is 80% of the diameter of the reactor, and the ratio of the height of the discharger to the diameter of the discharger 1:35, the ratio of the height of the packing block 8 in the rotating zone to the distance between the lower surface of the upper discharger and the upper surface of the lower discharger is 3:4. The packing is a plate corrugated mesh packing filled in a regular manner. The inner diameter of the feed pipe 2 is 1.7 times the inner diameter of the inner feed pipe 1.
[0046] The salt-forming reactor has a volume of 800L, in which 160Kg of o-dichlorobenzene is added as the reaction solvent in advance, the stirring is turned on, the temperature is controlled to 150°C, and the hydrogen chloride compressed gas is 60m 3 /h into the salt-forming reactor. After stirring for 10 minutes, the mixture of 1,3-cyclohexanedimethylamine and o-dichlorobenzene (amine concentration is 23.5wt%) is preheated to 140°C and heated to 113Kg The flow rate of 1/h enters the reverse salt formation reactor and reacts with hydrogen chloride. After 3 hours, the feeding is completed to obtain the amine hydrochloride solution, which is transferred to the phosgenation reactor through the liquid phase feed port 4, and the stirring is turned on at 500 rpm and the temperature is raised. To 160℃, 15m from gas phase feed port 5 3 Feed in hydrogen chloride at a rate of 1/h, stop the feed of hydrogen chloride gas after 30 minutes, and feed in nitrogen from the outer feed pipe 2 at a rate of 2 mol/min. The excess hydrogen chloride gas and nitrogen are discharged through the gas phase outlet 11, and after 30 minutes, salt The acid salt degassing is over, the hydrochloride concentration is 22.1wt%, and the average particle size of the hydrochloride particles is determined to be 15um. The phosgene is introduced through the inner feed pipe 1 at a feed rate of 8.5 mol/min. The feed pipe 2 continues to feed nitrogen at a rate of 2 mol/min. After the solution is clarified, the phosgene feed is stopped to obtain the photochemical reaction liquid, which is discharged from the liquid phase outlet 7 for dephosgene and solvent removal. The total amount of chlorinated by-products in the crude product is 575ppm; after separation and purification, 108.3Kg of 1,3-bis(methyl isocyanate)cyclohexane is obtained, and the total chlorine is 21ppm.

Example Embodiment

[0047] Example 3
[0048] The volume of the phosgenation reactor is 800L, and the discharger is perpendicular to the feed pipe. The ratio of the distance between the lower surface of the upper discharger and the upper surface of the lower discharger to the height of the reactor is 1:8, the upper and lower dischargers are of hollow cylindrical structure, and the lower surface of the upper discharger 10 And the upper surface of the lower discharger 6 is evenly distributed with triangular outlet small holes, the opening rate is 65%, the diameter of the discharger is 50% of the diameter of the reactor, and the ratio of the height of the discharger to the diameter of the discharger is 1: 40. The ratio between the height of the packing block 8 in the rotating zone and the distance between the lower surface of the upper discharger and the upper surface of the lower discharger is 1:2. The packing is a plate corrugated mesh packing filled in a regular manner, and the outer feeding pipe The inner diameter of 2 is 1.5 times the inner diameter of the inner feed pipe 1.
[0049] The salt-forming reactor has a volume of 800L, in which 200Kg of o-dichlorobenzene is added as the reaction solvent in advance, the stirring is turned on, the temperature is controlled to 150°C, and the hydrogen chloride compressed gas is heated to 35m 3 /h into the salt-forming reactor, after stirring for 10 minutes, the mixture of 1,3-cyclohexanedimethylamine and o-dichlorobenzene (amine concentration of 26.5wt%) is preheated to 140°C and heated to 60Kg The flow rate of /h enters the reaction salt formation reactor and reacts with hydrogen chloride. After 5 hours, the feeding is completed to obtain the amine hydrochloride solution, which is transferred to the phosgenation reactor through the liquid phase feed port 4, and the stirring is turned on at 500 rpm and the temperature is raised. To 160℃, 7m from gas phase feed port 5 3 Feed hydrogen chloride at a rate of 1/h, stop the feed of hydrogen chloride gas after 30 minutes, and feed nitrogen from the outer feed pipe 2 at a rate of 4 mol/min. The excess hydrogen chloride gas and nitrogen are discharged through the gas phase outlet 11, and after 30 minutes, the salt The acid salt degassing is over, the hydrochloride concentration is 22.2wt%, and the average particle size of the hydrochloride particles is determined to be 11um. The phosgene is introduced through the inner feed pipe 1 at a feed rate of 10mol/min, and at the same time, the outside Feed pipe 2 continues to feed nitrogen at a rate of 4 mol/min. After the solution is clarified, the phosgene feed is stopped to obtain the photochemical reaction liquid, which is discharged from the liquid phase outlet 7 for dephosgene and solvent removal. The total amount of chlorinated by-products in the crude product is 212ppm; after separation and purification, 107Kg of 1,3-bis(methyl isocyanate)cyclohexane is obtained, and the total chlorine is 14ppm.
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PUM

PropertyMeasurementUnit
Particle size367.0µm
tensileMPa
Particle sizePa
strength10

Description & Claims & Application Information

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