A method for the application of esterification tail gas in the synthesis of n-butyl isocyanate in salt formation

Abstract

The invention relates to a method for applying esterification tail gas produced in synthesis of butyl isocyanate to salification. The method comprises the following steps: (1) bubbling tail gas produced in a butyl isocyanate esterification reaction by using a solvent at the temperature of between 5 DEG C below zero and 0 DEG C below zero for absorbing, and introducing remaining gas hydrogen chloride condensed by a condenser into a salification kettle to undergo a salification reaction with n-butylamine; (2) bubbling the solvent in the step (1) for absorbing, and adding a 50-60wt% phosgene-containing solvent into a phosgene removing kettle; (3) heating the phosgene-containing solvent in the phosgene removing kettle to remove phosgene, wherein the removed phosgene is applied to an esterification reaction in the preparation of the butyl isocyanate; (4) heating the solvent from which the phosgene is removed, and introducing N2 to remove the phosgene, wherein the solvent from which phosgene is removed by introducing N2 is directly taken as the solvent in the step (1); (5) applying the tail gas produced in the step (3) to the butyl isocyanate esterification reaction. The method has the advantages of low energy consumption in the entire process, low cost, small equipment investment and small amount of waste acid.

Description

technical field [0001] The invention belongs to the field of organic chemistry, and in particular relates to a method for applying the esterification tail gas in the synthesis of n-butyl isocyanate to salt formation. This method can purify and separate the hydrogen chloride and phosgene in the tail gas of the esterification reaction during the preparation of n-butyl isocyanate, and the purified and separated hydrogen chloride gas can be directly passed into the n-butylamine salt-forming kettle to form salt, which can replace the original hydrochloric acid salt-forming process and reduce the cost. Water separation and energy loss in the salt process and increase the yield of the esterification reaction; the purified and separated phosgene is directly passed into the n-butylamine hydrochloride esterification tank for esterification. Background technique [0002] Benomyl is an efficient broad-spectrum systemic benzimidazole fungicide. It has good biological activity against ma...

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Problems solved by technology

[0004] The purpose of the present invention is to overcome the disadvantages of high equipment investment, high material loss and large pollution of the tail gas falling film absorption method for the preparation of n-butyl isocyanate esterification, and to provide a method for preparing n-butyl isocyanate during the synthesis of esterification tail gas in the process of salt formation The method applied in this method makes full use of hydrogen chloride and phosgene in the tail gas under the condition of ensuring the quality of n-butyl isocyanate, so as to reduce the amount of waste acid, energy consumption, cost and pollution

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