Method for preparing isophorone diisocyanate

Abstract

A method for preparing isophorone diisocyanate by (1) reacting isophorone with hydrogen cyanide in the presence of a catalyst to obtain isophorone nitrile; (2) reacting the isophorone nitrile obtained in step (1) with ammonia gas and hydrogen in the presence of a catalyst to obtain isophorone diamine; and (3) subjecting the isophorone diamine to a phosgenation reaction to obtain the isophorone diisocyanate, wherein the content of impurities containing a secondary amine group in the isophorone diamine that undergoes the phosgenation reaction in step (3) is ?0.5 wt. The method reduces the content of hydrolyzed chlorine in the isophorone diisocyanate product, improves the yellowing resistance of the product, and the harm due to presence of hydrolyzed chlorine in the product is reduced.

Claims

1. A method for preparing isophorone diisocyanate, comprising the following steps: (1) reacting isophorone with hydrogen cyanide in the presence of a catalyst to obtain isophorone nitrile; (2) reacting the isophorone nitrile obtained in step (1) with ammonia gas and hydrogen in the presence of a catalyst to obtain isophorone diamine; and (3) subjecting the isophorone diamine to a phosgenation reaction to obtain isophorone diisocyanate, wherein the content of impurities containing a secondary amine group in the isophorone diamine that is subjected to the phosgenation reaction in step (3) is less than or equal to 0.5 wt %.

2. The method according to claim 1, wherein the ammonia gas in step (2) has a methylamine content of less than or equal to 0.5 wt %.

3. The method according to claim 1, wherein the hydrogen cyanide in step (1) has an olefins content of less than or equal to 0.3 wt %.

4. The method according to claim 3, wherein the olefins comprise one or more of ethylene, propylene, butylene, butadiene or isobutylene.

5. The method according to claim 1, wherein in step (1), the material molar ratio of hydrogen cyanide, isophorone and catalyst is 1:1-3:0.005-0.03.

6. The method according to claim 1, wherein the catalyst in step (1) is an oxide, a hydroxide, a cyanide, an alkyl alcoholate or a carbonate of an alkali metal or alkaline earth metal, a tertiary amine, a quaternary phosphine base or a quaternary ammonium base.

7. The method according to claim 1, wherein in step (2), the catalyst is a catalyst with an active component of cobalt or nickel.

8. The method according to claim 1, wherein the phosgenation reaction in step (3) is any one of gas phase phosgenation reaction, a cold-hot phosgenation reaction, or a salification phosgenation reaction.

9. The method according to claim 1, wherein the phosgenation reaction in step (3) is a reaction of isophorone diamine with at least one member selected from the group consisting of phosgene, diphosgene, triphosgene, fluorophosgene and bromophosgene.

10. The method according to claim 1, wherein the hydrogen cyanide in step (1) has an olefins content of less than or equal to 0.1 wt %.

11. The method according to claim 2, wherein the hydrogen cyanide in step (1) has an olefins content of less than or equal to 0.3 wt %.

12. The method according to claim 2, wherein the hydrogen cyanide in step (1) has an olefins content of less than or equal to 0.1 wt %.

13. The method according to claim 2, wherein the phosgenation reaction in step (3) is any one of gas phase phosgenation reaction, a cold-hot phosgenation reaction, or a salification phosgenation reaction.

14. The method according to claim 3, wherein the phosgenation reaction in step (3) is any one of gas phase phosgenation reaction, a cold-hot phosgenation reaction, or a salification phosgenation reaction.

15. The method according to claim 4, wherein the phosgenation reaction in step (3) is any one of gas phase phosgenation reaction, a cold-hot phosgenation reaction, or a salification phosgenation reaction.

16. The method according to claim 5, wherein the phosgenation reaction in step (3) is any one of gas phase phosgenation reaction, a cold-hot phosgenation reaction, or a salification phosgenation reaction.

17. The method according to claim 6, wherein the phosgenation reaction in step (3) is any one of gas phase phosgenation reaction, a cold-hot phosgenation reaction, or a salification phosgenation reaction.

18. The method according to claim 7, wherein the phosgenation reaction in step (3) is any one of gas phase phosgenation reaction, a cold-hot phosgenation reaction, or a salification phosgenation reaction.

19. The method according to claim 1, wherein the phosgenation reaction in step (3) a salification phosgenation reaction.

20. The method according to claim 2, wherein the phosgenation reaction in step (3) is a gas phase phosgenation reaction.

Description

DETAILED DESCRIPTION

(1) The technical solutions and effects thereof of the present disclosure will be further described hereinafter through the specific examples. It is to be understood that the examples described below are intended to illustrate the present disclosure but are not be construed to limit the scope thereof. The simple modifications made to the present disclosure in according with the concept of the present disclosure are within the scope of the present disclosure.

(2) The test methods used in the embodiments of the present disclosure are as follows:

(3) (1) The quantitative analysis of methylamine in ammonia gas was carried out on gas chromatography under the following conditions:

(4) chromatographic column was PLOT GDX-203 (specification: 30 m*0.53 mm*5.00 ?m), the injector temperature was 50? C., the column flow was 1.5 ml/min, the column temperature was 50? C. and maintained for 1 min and then raised to 135? C. at 5? C./min and maintained for 8 min, the detector temperature was 140? C., the H.sub.2 flow was 60 ml/min, and the air flow was 350 ml/min.

(5) (2) The quantitative analysis of the impurities containing the secondary amine group in IPDA was carried out on gas chromatography under the following conditions:

(6) chromatographic column was Agilent HP-5 (specification: 30 m*0.32 mm*0.25 ?m), the injector temperature was 280? C., the split ratio was 30:1, the column flow was 1.5 ml/min, the column temperature was 100? C. and maintained for 0.5 min and then raised to 260? C. at 15? C./min and maintained for 8 min, the detector temperature was 280? C., and the H.sub.2 flow was 35 ml/min.

(7) (3) The analysis of the content of hydrolyzed chlorine in IPDI used the method mentioned in the Chinese national standard GB/T 12009.2-1989.

(8) (4) The analysis of the chromaticity index in IPDI used the method mentioned in the Chinese national standard GB/T605-2006.

(9) (5) The quantitative analysis of the content of olefins in hydrogen cyanide was carried out on the gas chromatography under the following conditions:

(10) chromatographic column was Agilent HP-5 (specification: 30 m*0.53 mm*5.00 ?m), the injector temperature was 50? C., the column flow was 1.5 ml/min, the column temperature was 50? C. and maintained for 1 min and then raised to 135? C. at 5? C./min and maintained for 8 min, the detector temperature was 140? C., the H.sub.2 flow was 60 ml/min, and the air flow was 350 ml/min.

Example 1

(11) (1) Isophorone was supplied to a preheater at a rate of 200 kg/h and preheated to the reaction temperature of 120? C., and then isophorone, HCN and sodium methoxide serving as the basic catalyst in a molar ratio of 2:1:0.003 were supplied to the reactor disclosed in Example 1 of CN103301799B which operated under the operating conditions as disclosed in CN103301799B and reacted at an absolute pressure of 1 MPa to obtain isophorone nitrile (IPN) after 25 min of reaction.

(12) The content of olefinic impurities in the HCN used in step (1) was 0.01 wt %.

(13) (2) The isophorone nitrile obtained in step (1) was reacted with ammonia gas and hydrogen in the presence of a catalyst, wherein the specific reaction was as follows:

(14) a) The isophorone nitrile obtained in step (1) was reacted with ammonia gas in a tubular reactor at a temperature of 60? C. and an absolute pressure of 15 MPa to obtain 3-cyano-3,5,5-trimethylcyclohexylimine, wherein the molar ratio of ammonia gas to isophorone nitrile was 50:1.

(15) b) In the presence of a hydrogenation catalyst Raney cobalt at a space velocity of 1.5 g of 3-cyano-3,5,5-trimethylcyclohexanone/(milliliter of catalyst.Math.hour), hydrogen, NH.sub.3, and 3-cyano-3,5,5-trimethylcyclohexylimine obtained in step a) were mixed in 3% KOH ethanol solution and then reacted at a temperature of 80? C. and an absolute pressure of 18 MPa to obtain a product containing 3-aminomethyl-3,5,5-trimethylcyclohexylamine (IPDA) and 3-cyano-3,5,5-trimethylcyclohexylamine.

(16) In step b), the mass ratio of the KOH ethanol solution to the added isophorone nitrile was 1:600, the molar ratio of NH.sub.3 to isophorone nitrile was 50:1, and the molar ratio of hydrogen to isophorone nitrile was 80:1.

(17) c) In the presence of a hydrogenation catalyst Raney cobalt at a space velocity of 1.8 g of 3-cyano-3,5,5-trimethylcyclohexanone/(milliliter of catalyst.Math.hour), hydrogen, NH.sub.3, and the product containing 3-aminomethyl-3,5,5-trimethylcyclohexylamine (IPDA) and 3-cyano-3,5,5-trimethylcyclohexylamine obtained in step b) were mixed in 3% acetic acid-ethanol solution and then reacted at a temperature of 120? C. and an absolute pressure of 18 MPa to convert 3-cyano-3,5,5-trimethylcyclohexylamine to 3-aminomethyl-3,5,5-trimethylcyclohexylamine (IPDA). After the test, the content of impurities containing the secondary amine group in IPDA was 0.4 wt %.

(18) In step c), the mass ratio of the acetic acid-ethanol solution to IPN obtained in step (1) was 1:500, the molar ratio of hydrogen to IPN obtained in step (1) was 30:1, and the molar ratio of ammonia gas to IPN obtained in step (1) was 50:1.

(19) The content of methylamine in the ammonia gas used in each step of step (2) was 0.45 wt %.

(20) (3) The obtained IPDA was gasified and heated to 355? C. by using the heater mentioned in Example 1 of Chinese Patent No. CN105214568A, and under the protection of nitrogen gas, the gasified IPDA and gaseous phosgene heated to 355? C. were continuously fed into the reactor through respective feed pipes and then reacted at an absolute pressure of 0.05 MPa and a temperature of 360? C., wherein the feed amount of IPDA was 800 Kg/h and the feed amount of the phosgene was 3000 Kg/h. The mixed gas obtained after the reaction was rapidly cooled to 100? C. by means of a gas injection absorption device using o-dichlorobenzene solution to obtain a photochemical liquid containing the product IPDI. Excess phosgene was removed at 180? C. and an absolute pressure of 0.1 MPa to obtain a crude IPDI product free of phosgene. The crude product was subsequently rectified by means of a rectifying column, and a IPDI product under the distillation of 0.5 KPa and 150? C. to 160? C. was collected, whose yield and purity were 95% and 99.5%, respectively.

Example 2

(21) This example differs from Example 1 in that step (3) was carried out in a reaction kettle mentioned in Chinese patent No. CN103319372B:

(22) a) cold reaction: the IPDA obtained in step (2) was prepared as a solution in which the content of IPDA was 15% by mass using chlorobenzene as the solvent and preheated to 40? C., and the IPDA solution was fed to a reaction kettle containing chlorobenzene simultaneously with a liquid phosgene at ?5? C. to perform a liquid phosgenation reaction, wherein the feed amount of IPDA was 400 Kg/h, the feed amount of phosgene of the cold reaction was 1500 kg/h, the temperature of the cold reaction was controlled at 60? C., and the residence time was 5 min.

(23) b) hot reaction: a photochemical liquid containing the product IPDI was obtained in the conditions that the temperature was controlled at 140? C. and the residence time was 2 h; excess phosgene was removed at 180? C. and an absolute pressure of 0.1 MPa to obtain a crude product IPDI free of phosgene; and the crude product was subsequently rectified by means of a rectifying column, and an IPDI product under the distillation of 0.5 KPa and 150? C. to 160? C. was collected, whose yield and purity were 96% and 99.5%, respectively.

Example 3

(24) This example differs from Example 1 in the following aspects:

(25) 1. The content of olefins in hydrogen cyanide in step (1) was 0.25 wt %.

(26) 2. The content of impurities containing the secondary amine group in IPDA obtained after step (2) was 0.45 wt %.

(27) 3. In step (3), the preparation was carried out in a reaction kettle mentioned in Example 1 of Chinese patent No. CN105218422B using the following method:

(28) a) 1000 Kg of o-dichlorobenzene was pre-added in a salification reaction kettle as the reaction solvent, a circulation pump was turned on and stirred the reaction solution, hydrogen chloride compressed gas was supplied through a pre-mixer into the reactor at a speed of 50 mol/min and stirred for 15 min, and a mixture liquid of IPDA and o-dichlorobenzene (the concentration of fed amine was 20 wt %) was heated through a raw material preheater to 30? C. and fully contacted with hydrogen chloride gas at a flow rate of 335 Kg/h to perform a salification reaction. The reaction was cooled with external circulating cooling water to remove a part of the heat of the reaction, wherein the flow rate of the circulating liquid was about 5 m.sup.3/h and the temperature of the reaction liquid was maintained at 30? C. to 45? C. After 3 hours of feeding, the mixed liquid of IPDA and o-dichlorobenzene was stopped, and the HCl gas was continuously introduced for 30 min.

(29) b) The resulting IPDA hydrochloride slurry was transferred to a photochemical reactor having a phosgene inlet pipe, gas phase condensation reflux and stirring. The photochemical reaction kettle was heated up while stirring was started. After the temperature reached 60? C., phosgene was introduced into the photochemical reaction kettle, wherein the feed rate of phosgene was 50 mol/min and the reaction temperature was 130? C. The phosgene feeding was stopped after the photochemical liquid was clarified to obtain the salification photochemical reaction liquid. Excess phosgene was removed at 180? C. and an absolute pressure of 0.1 MPa to obtain a crude IPDI product free of phosgene. The crude product was subsequently rectified by means of a rectifying column, and an IPDI product under the distillation of 0.5 KPa and 150? C. to 160? C. was collected, whose yield and purity were 95% and 99.5%, respectively.

Example 4

(30) This example differs from Example 3 in that the content of methylamine in the ammonia gas used in each step of step (2) was 0.25 wt % and the content of impurities containing the secondary amine group in the obtained IPDA was 0.35 wt %.

Comparative Example 1

(31) This comparative example differs from Example 1 in that the content of methylamine in the ammonia gas used in each step of step (2) was 0.75 wt %, the content of impurities containing the secondary amine group in the obtained IPDA was 0.75 wt %, and the yield and purity of the product were 95% and 99.5%, respectively.

Comparative Example 2

(32) This comparative example differs from Example 1 in that the content of olefinic impurities in the HCN used in step (1) was 0.75 wt %, the content of methylamine in the ammonia gas used in each step of step (2) was 0.75 wt %, the content of impurities containing the secondary amine group in the obtained IPDA was 0.95 wt %, and the yield and purity of the product were 95% and 99.5%, respectively.

Comparative Example 3

(33) This comparative example differs from Example 3 in that the content of methylamine in the ammonia gas used in each step of step (2) was 0.75 wt %, the content of impurities containing the secondary amine group in the obtained IPDA was 0.75 wt %, and the yield and purity of the product were 96% and 99.5%, respectively.

Comparative Example 4

(34) This comparative example differs from Example 1 in that the content of methylamine in the ammonia gas used in each step of step (2) was 0.75 wt %, the content of impurities containing the secondary amine group in the obtained IPDA was 0.75 wt %, and the yield and purity of the product were 95% and 99.5%, respectively.

Comparative Example 5

(35) This comparative example differs from Example 1 in that the content of olefinic impurities in the HCN used in step (1) was 0.75 wt %, the content of impurities containing the secondary amine group in the IPDA obtained in step (2) was 0.85 wt %, and the yield and purity of the product were 95% and 99.5%, respectively.

(36) After testing, parameters in the above examples and comparative examples and the test results of the content and chromaticity of hydrolyzed chlorine in the products are shown in Table 1.

(37) TABLE-US-00001 TABLE 1 Step (2) Step (1) Content of Content of impurities olefins in Content of containing the Step (3) hydrogen methylamine in secondary amine Hydrolyzed cyanide ammonia gas group in IPDA chlorine Chromaticity (wt %) (wt %) (wt %) (ppm) (Hazen) Example 1 0.01 0.45 0.4 12 10 Example 2 0.01 0.45 0.4 8 5 Example 3 0.25 0.45 0.45 10 7.5 Example 4 0.25 0.25 0.35 15 10 Comparative 0.01 0.75 0.75 80 75 example 1 Comparative 0.75 0.75 0.95 95 85 example 2 Comparative 0.25 0.75 0.75 89 60 example 3 Comparative 0.01 0.75 0.75 87 55 example 4 Comparative 0.75 0.45 0.85 90 70 example 5

(38) As can be seen from the data in the above table, in the present disclosure, the content of olefins in the raw material HCN and the content of methylamine in the ammonia gas in the preparation process of the IPDA are controlled so that the secondary amine impurities in the IPDA are controlled 0.5 wt % or less and thus the chromaticity of the IPDI obtained after phosgenation and the hydrolyzed chlorine in the IPDI are at a very low level, thereby reducing the reject ratio of the downstream product from the source.