SOLVENT REFINING METHOD FOR ISOCYANATE PREPARED BY PHOSGENE METHOD AND DEVICES USED IN SAME
원문보기
IPC분류정보
국가/구분
United States(US) Patent
공개
국제특허분류(IPC7판)
C07C-263/20
B01D-015/10
출원번호
US-0301132
(2014-04-11)
공개번호
US-0022152
(2017-01-26)
우선권정보
CN-201410128614.8 (2014-04-01)
국제출원번호
PCT/CN2014/075169
(2014-04-11)
발명자
/ 주소
Zhang, Hongke
Yao, Yu
Zhao, Dongke
Hua, Weiqi
Chen, Bin
Shi, Dekai
Chen, Qinglong
Xu, Dan
Wang, Yang
Shi, Qile
출원인 / 주소
Wanhua Chemical Group Co., Ltd.
인용정보
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초록▼
A solvent refining method for isocyanate prepared by the phosgene method and multistage absorbing towers used in same. Solvent to be refined which contains water, iron, and/or phosgene, hydrogen chloride and other materials with color is dealt by the present method and multistage absorbing towers, w
A solvent refining method for isocyanate prepared by the phosgene method and multistage absorbing towers used in same. Solvent to be refined which contains water, iron, and/or phosgene, hydrogen chloride and other materials with color is dealt by the present method and multistage absorbing towers, which can effectively prevent a drying agent from absorbing water and hardening, partial overheating in the tower and generating channeling. Meanwhile, the pressure drop is effectively lowered. In addition, the content of water is ≦50 ppm, the content of iron is ≦5 ppm, the content of phosgene and hydrogen chloride is ≦20 ppm, Pt—Co chroma is ≦20 in the refined solvent. Therefore, the refined solvent can be used as the solvent for preparing isocyanate in the phosgene method and remarkably improve an L color of isocyanate.
대표청구항▼
1. A solvent refining method for isocyanates prepared by the phosgene method, wherein the solvents to be refined is treated with a multistage absorption tower comprising a support packing section at the bottom, a packing absorbing section in the middle and a support packing section on top from botto
1. A solvent refining method for isocyanates prepared by the phosgene method, wherein the solvents to be refined is treated with a multistage absorption tower comprising a support packing section at the bottom, a packing absorbing section in the middle and a support packing section on top from bottom to top; the packing absorption section in the middle comprises N absorbing layers, and N is an integer from 3 to 8, preferably N is an integer from 4 to 6; from the first absorbing layer to the Nth absorbing layer, the layers are arranged from bottom to top; from the first absorbing layer to the (N−1)th absorbing layer, each layer of these layers is composed of an upper liquid distributing device that connects an external feeding pipe and a lower absorbing packing layer, and the absorbing packing layer of every of the absorbing layers is formed by the uniform mixing of desiccants and adsorbents. 2. The method according to claim 1, wherein the weight ratio of the desiccants to the adsorbents of the absorbing packing layer of the first absorbing layer is 1:1-5:1, preferably 2:1-4:1, and the desiccants represent 4-15% of the weight of all the desiccants in the multistage absorption tower, preferably 5-10%; the weight ratio of the desiccants to the adsorbents of the absorbing packing layer of the Nth absorbing layer is 5:1-12:1, preferably 6:1-10:1, and the desiccants represent 4-15% of the weight of all the desiccants in the multistage absorption tower, preferably 5-10%; the weight ratio of the desiccants to the adsorbents of the absorbing packing layer of every of the second absorbing layer to the (N−1)th absorbing layer is 5:1-15:1, preferably 6:1-10:1, and the desiccants of every of the absorbing packing layers represent 15-92% of the weight of all the desiccants in the multistage absorption tower, preferably 20-45%. 3. The method according to claim 1, wherein the desiccants are alkaline desiccants, which are selected from one or two or more of calcium oxide, sodium hydroxide and potassium hydroxide, preferably sodium hydroxide; the BET specific surface area of the desiccants is 1500-4500 m2/g, preferably 2500-4000 m2/g; the average particle size is 0.5-10 μm, preferably 1.5 μm; the mechanical strength is 85-99%, preferably 90-98%. 4. The method according to claim 1, wherein the adsorbents are macroporous resin adsorbents or activated carbon; the macroporous resin adsorbents are selected from one or two or more of nonpolar macroporous adsorption resins of styrene polymer and nonpolar macroporous adsorption resins of divinylbenzene polymer, preferably selected from one or two or more of D101, LX-60 and LX-20; the activated carbon is preferably coconut shell activated carbon; the BET specific surface area of the adsorbents is 2500-5000 m2/g, preferably 3000-4500 m2/g; the pore size of mesoporous is 2-10 nm, preferably 2-5 nm; the mechanical strength is 85-98%, preferably 90-95%. 5. The method according to claim 1, wherein the support packings of the support packing section on top and the support packing section at the bottom are selected from one or two or more of gravels, molecular sieves and activated carbon, preferably molecular sieves, more preferably 3A type molecular sieve; the weight of the support packings in the support packing section on top and the weight of the support packings in the support packing section at the bottom are the same, and the weight ratio of the support packings in the support packing section on top to all the desiccants in the multistage absorption tower is 1:20-1:3, preferably 1:15-1:5. 6. The method according to claim 1, wherein the ratio of the volume flow rate of the total feed rate of the solvents to be refined to the total weight of all the desiccants and the adsorbents in the multistage absorption tower is 1:200-1:600 m3/kg/h, preferably 1:300-1:500 m3/kg/h. 7. The method according to claim 6, wherein the feeding volume of the external feeding pipe of the first absorbing layer represents 1/15-1/3, preferably 1/10-1/5 of the total feeding volume of the solvents to be refined, the feeding amount of the external feeding pipe of the (N−1)th absorbing layer represents 1/15-1/3, preferably 1/10-1/5 of the total feeding volume of the solvents to be refined, and the feeding amount of the external feeding pipe of every of the absorbing layers, from the second absorbing layer to the (N−2)th absorbing layer, represents 1/15-4/5, preferably 1/10-7/10 of the total feeding amount of the solvents to be refined. 8. The method according to claim 7, wherein the residence time of the solvents to be refined in the multistage absorption tower is 0.25-8 hrs, preferably 2-4 hrs. 9. The method according to claim 6, wherein the refined solvents partially reflux and enter into the multistage absorption tower after mixing with the solvents to be refined, and the reflux ratio is 0.5-4, preferably 1-3; the pressure drop between the external feeding pipe of the first absorbing layer of the multistage absorption tower and the outlet on top of the tower is 5-40 kPa, preferably 10-25 kPa. 10. The method according to claim 1, wherein the solvents to be refined are the waste solvents that contains impurities generated during the preparation of isocyanates by the phosgene method or the fresh solvents that should be added to the reaction system during preparation of isocyanates because of the consumption of solvents, and the content of water, iron and the color number in the fresh solvents fail to reach standards; the solvents are selected from one or two or more of o-dichlorobenzene, chlorobenzene and toluene; the content of water in the solvents to be refined is 150-600 ppm, preferably 200-300 ppm; the content of iron component is 40-300 ppm, preferably 50-200 ppm; the content of phosgene and hydrogen chloride is 0-10000 ppm, preferably 0-5000 ppm; the Pt—Co color number is 30-100, preferably 40-80; the content of water in the refined solvents is ≦50 ppm, the content of iron component is ≦5 ppm, the content of phosgene and hydrogen chloride is ≦20 ppm, and Pt—Co color number is ≦20. 11. A multistage absorption tower used for refining solvents generated in the preparation of isocyanates by the phosgene method, comprising: a support packing section at the bottom;a packing absorbing section in the middle;a support packing section on top from bottom to top;wherein the packing absorbing section in the middle comprises N absorbing layers, and N is an integer from 3 to 8, preferably N is an integer from 4 to 6; from the first absorbing layer to the Nth absorbing layer, the layers are arranged from bottom to top; from the first layer to the (N−1)th absorbing layer, each layer of these layers is composed of an upper liquid distributing device that connects an external feeding pipe and a lower absorbing packing layer, and the absorbing packing layer of every of the absorbing layers is formed by the uniform mixing of desiccants and adsorbents. 12. The multistage absorption tower according to claim 11, wherein the weight ratio of the desiccants to the adsorbents of the absorbing packing layer of the first absorbing layer is 1:1-5:1, preferably 2:1-4:1, and the desiccants represent 4-15% of the weight of all the desiccants in the multistage absorption tower, preferably 5-10%; the weight ratio of the desiccants to the adsorbents of the absorbing packing layer of the Nth absorbing layer is 5:1-12:1, preferably 6:1-10:1, the desiccants represent 4-15% of the weight of all the desiccants in the multistage absorption tower, preferably 5-10%; the weight ratio of the desiccants to the adsorbents of the absorbing packing layer of every of the second absorbing layer to the (N−1)th absorbing layer is 5:1-15:1, preferably 6:1-10:1, and the desiccants of every of the absorbing packing layers represent 15-92% of the weight of all the desiccants in the multistage absorption tower, preferably 20-45%. 13. The multistage absorbing tower according to claim 11, wherein the desiccants are alkaline desiccant, which are selected from one or two or more of calcium oxide, sodium hydroxide and potassium hydroxide, preferably sodium hydroxide; the BET specific surface area of the desiccants is 1500-4500 m2/g, preferably 2500-4000 m2/g; the average particle size is 0.5-10 μm, preferably 1.5 μm; the mechanical strength is 85-99%, preferably 90-98%. 14. The multistage absorbing tower according to claim 11, wherein the adsorbents are macroporous resin adsorbents or activated carbon; the macroporous resin adsorbents are selected from one or two or more of nonpolar macroporous adsorption resins of styrene polymer and nonpolar macroporous adsorption resins of divinylbenzene polymer, preferably selected from one or two or more of D101, LX-60 and LX-20; the activated carbon is preferably coconut shell activated carbon; the BET specific surface area of the adsorbents is 2500-5000 m2/g, preferably 3000-4500 m2/g; the pore size of mesoporous is 2-10 nm, preferably 2-5 nm; the mechanical strength is 85-98%, preferably 90-95%. 15. The multistage absorbing tower according to claim 11, wherein the support packings of the support packing section on top and the support packing section at the bottom are selected from one or two or more of gravels, molecular sieves and activated carbon, preferably molecular sieves, more preferably 3A type molecular sieve; the weight of the support packings in the support packing section on top and the weight of the support packing in the support packing section at the bottom are the same, and the weight ratio of the support packing in the support packing section on top to all the desiccants in the multistage absorption tower is 1:20-1:3, preferably 1:15-1:5. 16. Use of the multistage absorption tower according to claim 11 in the preparation of isocyanates by the phosgene method. 17. The method according to claim 2, wherein the desiccants are alkaline desiccants, which are selected from one or two or more of calcium oxide, sodium hydroxide and potassium hydroxide, preferably sodium hydroxide; the BET specific surface area of the desiccants is 1500-4500 m2/g, preferably 2500-4000 m2/g; the average particle size is 0.5-10 μm, preferably 1.5 μm; the mechanical strength is 85-99%, preferably 90-98%. 18. The method according to claim 2, wherein the adsorbents are macroporous resin adsorbents or activated carbon; the macroporous resin adsorbents are selected from one or two or more of nonpolar macroporous adsorption resins of styrene polymer and nonpolar macroporous adsorption resins of divinylbenzene polymer, preferably selected from one or two or more of D101, LX-60 and LX-20; the activated carbon is preferably coconut shell activated carbon; the BET specific surface area of the adsorbents is 2500-5000 m2/g, preferably 3000-4500 m2/g; the pore size of mesoporous is 2-10 nm, preferably 2-5 nm; the mechanical strength is 85-98%, preferably 90-95%. 19. The method according to claim 3, wherein the adsorbents are macroporous resin adsorbents or activated carbon; the macroporous resin adsorbents are selected from one or two or more of nonpolar macroporous adsorption resins of styrene polymer and nonpolar macroporous adsorption resins of divinylbenzene polymer, preferably selected from one or two or more of D101, LX-60 and LX-20; the activated carbon is preferably coconut shell activated carbon; the BET specific surface area of the adsorbents is 2500-5000 m2/g, preferably 3000-4500 m2/g; the pore size of mesoporous is 2-10 nm, preferably 2-5 nm; the mechanical strength is 85-98%, preferably 90-95%. 20. The method according to claim 2, wherein the ratio of the volume flow rate of the total feed rate of the solvents to be refined to the total weight of all the desiccants and the adsorbents in the multistage absorption tower is 1:200-1:600 m3/kg/h, preferably 1:300-1:500 m3/kg/h.
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