| 摘要 |
A process for preparing toluene diisocyanate is provided to minimize energy consumption and cost required for post-treatment of the distillation residue, while improving the yield of toluene diisocyanate. A process for preparing toluene diisocyanate comprises the steps of: (a) reacting toluene diamine with phosgene to form crude toluene diisocyanate; (b) purifying the crude toluene diisocyanate via distillation to form a mixture containing toluene diisocyanate and distillation residue and purified toluene diisocyanate; (c) mixing the mixture continuously with water in at least one tubular reactors linked in series under an absolute pressure of less than 30 bars at a temperature of lower than 230 deg.C, and reacting the mixture with water under the above condition to form toluene diamine; (d) optionally, purifying the toluene diamine formed in step (c); and (e) recycling at least a part of the toluene diamine to step (a).
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