Method for obtaining hydrogen chloride having low light component content in isocyanate production process

By reducing the content of light component impurities in liquid phosgene, the problem of difficult control of the temperature stability of the hydrogen chloride catalytic oxidation reactor is solved, and the stability of the isocyanate production process is improved.

WO2025054891A1 Publication Date: 2025-03-20WANHUA CHEM GRP CO LTD
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Patent Information

Application Number
PCT/CN2023/118766
Authority / Receiving Office
WO · WO
Patent Type
Applications
Current Assignee / Owner
Filing Date
2023-09-14
Publication Date
2025-03-20

AI Technical Summary

Technical Problem

During the isocyanate production process, the temperature stability of the hydrogen chloride catalytic oxidation reactor is difficult to control, resulting in a decrease in the catalyst life and fluctuation in the yield of chlorine gas, affecting the stability of the isocyanate manufacturing process.

Method used

By reducing the content of light component impurities in the liquid phosgene stream, the content of light component impurities is controlled within a certain range, thereby reducing the content of light component in hydrogen chloride, the by-product obtained in isocyanate production process, and reducing the temperature of the catalyst bed in the catalytic oxidation reaction and controlling the stability of the catalyst bed.

Benefits of technology

It effectively reduces the catalyst temperature of the hydrogen chloride catalytic oxidation reactor, avoids abnormal stopping caused by catalyst overtemperature or temperature fluctuations, and improves the stability of the isocyanate production process.

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Abstract

The present invention belongs to the technical fields of phosgene preparation and isocyanate preparation, and in particular relates to a method for obtaining hydrogen chloride having a low light component content in the process of isocyanate production. The method comprises: (1) synthesizing phosgene from a chlorine stream and a carbon monoxide stream catalyzed by a catalyst; controlling an inlet temperature of a catalyst bed of a phosgene synthesis reactor to be 110°C or above, and a maximum temperature to be 450°C or below; (2) condensing and separating an obtained gas phase stream I, to obtain a liquid phosgene stream having a low light component i content; (3) feeding the liquid phosgene stream into an isocyanate synthesis process for reaction, and condensing and removing impurities from a generated gas phase stream II, to obtain a hydrogen chloride stream having a low light component ii content. The method of the present invention can control the light component impurity content in a hydrogen chloride byproduct material to be within a relatively low range, so that the catalyst temperature of a hydrogen chloride catalytic oxidation reactor using said hydrogen chloride as a raw material remains stable, thereby improving the stability of an isocyanate production process.
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