Method for preparing isocyanate by combining supercritical phosgenation method with piping method
AssigneeMojia (Shanghai) Biotech Co., Ltd
InventorsYonghe XUE, Chengliang LU, Man Kit LAU, Haixin YUAN, Jiate LIU, Ansen CHIEW
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Abstract
The present application relates to a method for preparing an isocyanate. Specifically, the present application provides a method for preparing an isocyanate by combining a supercritical phosgenation method with a piping method.
Claims42
A method for preparing an isocyanate, comprising the following steps:
- (a) mixing a reactant amine stream and a phosgene stream at a temperature of −5 to 5° C., to obtain a mixture of reactant amine and phosgene;
- (b) adjusting the temperature of the mixture obtained in Step (a) to 182° C. to 205° C. so that the phosgene is in a supercritical state, and reacting in a supercritical reactor for at least 15 minutes;
- (c) reacting the reaction product mixture obtained in Step (b) under the condition of reduced pressure, for a reaction time of no more than 30 seconds.
The method according to any one of the preceding claims, wherein Step (a) is carried out before Step (b) and Step (c).
The method according to any one of the preceding claims, wherein no organic solvents are used in each of the Step (a), Step (b), and Step (c).
The method according to any one of the preceding claims, wherein in Step (a), the reactant amine stream and the phosgene stream are introduced and mixed in the supercritical fluid reactor.
The method according to any one of the preceding claims, wherein in Step (a), the mixed reactant amine stream and the phosgene stream form suspended particles by shear emulsification.
The method according to any one of the preceding claims, wherein in Step (a), the reactant amine stream and the phosgene stream pass through a homogenization pump for shear emulsification uniformly.
The method according to any one of the preceding claims, wherein the phosgene stream in Step (a) is stoichiometric excess relative to the amino groups of the reactant amine stream.
The method according to any one of the preceding claims, wherein the feed ratio (molar ratio) of the phosgene stream and the reactant amine stream in Step (a) is from 7:1 to 25:1 (preferably 12:1).
The method according to any one of the preceding claims, wherein the phosgene stream in Step (a) exists in liquid form.
The method according to any one of the preceding claims, wherein the reaction temperature in Step (c) is 150° C. to 450° C., preferably 200° C. to 400° C., more preferably 250° C. to 350° C.
The method according to any one of the preceding claims, wherein the reaction pressure in Step (c) is 15 KPa to 500 KPa, preferably 50 KPa to 300 KPa, more preferably 50 KPa to 110 KPa.
The method according to any one of the preceding claims, wherein the residence time during the reaction in Step (c) is 0.5 seconds to 30 seconds, preferably 1.5 seconds to 20 seconds, more preferably 2.5 seconds to 10 seconds.
The method according to any one of the preceding claims, wherein the reduced pressure reactor is a tubular reactor.
The method according to any one of the preceding claims, wherein the inner diameter of the pipe in the reduced pressure reactor is 4 to 9 mm.
The method according to any one of the preceding claims, wherein the isocyanate is a diisocyanate.
The method according to any one of the preceding claims, wherein the isocyanate is an aliphatic diisocyanate or an aromatic diisocyanate.
The method according to any one of the preceding claims, wherein the isocyanate is selected from the group consisting of methylene diphenyl diisocyanate as a pure isomer or as a mixture of isomers, toluene diisocyanate as a pure isomer or as a mixture of isomers, 2,6-xylyl isocyanate, 1,5-naphthalene diisocyanate, methyl isocyanate, ethyl isocyanate, propyl isocyanate, isopropyl isocyanate, butyl isocyanate, isobutyl isocyanate, t-butyl isocyanate, pentyl isocyanate (e.g., pentamethylene diisocyanate), t-pentyl isocyanate, isopentyl isocyanate, neopentyl isocyanate, hexyl isocyanate (e.g., hexamethylene diisocyanate), cyclopentyl isocyanate, cyclohexyl isocyanate, and phenyl isocyanate (e.g., p-phenylene diisocyanate).
The method according to any one of the preceding claims, wherein the isocyanate is PDI, HDI, IPDI or HTDI.
The method according to any one of the preceding claims, wherein the reactant amine has a structural formula of R(NH2)n, wherein n is 1, 2 or 3, and R is an aliphatic or aromatic hydrocarbyl group.
The method according to any one of the preceding claims, wherein the reactant amine exists in a free form.
The method according to any one of the preceding claims, wherein the reactant amine exists as an amine salt.
The method according to any one of the preceding claims, wherein the reactant amine is one or more selected from the group consisting of ethyl amine, butyl amine, pentamethylene diamine, hexamethylene diamine, 1,4-diamino butane, 1,8-diamino octane, aniline, p-phenylene diamine, m-xylylene diamine, toluene diamine, 1,5-naphthalene diamine, diphenylmethane diamine, dicyclohexylmethane diamine, m-cyclohexyldimethylene diamine, isophorone diamine, methyl cyclohexane diamine, and trans-1,4-cyclohexane diamine.
The method according to any one of the preceding claims, wherein the reactant amine is selected from the group consisting of PDA, PDA hydrochloride, HDA, HDA hydrochloride, IPDA, IPDA hydrochloride, HTDA, and HTDA hydrochloride.
Dependencies are inferred from the claim text.