Novel method for absorbing tail gas from trichloro-acetic chloride production through chlorination process

Abstract

The present invention relates to a novel method for absorbing tail gas from trichloro-acetic chloride production through a chlorination process. The method can realize separation and recovery of hydrogen chloride, sulfur dioxide, sulfur, disulfur dichloride, and chlorine generated in the production process of trichloro-acetic chloride; the method is safe and easily controlled, has no harm to the environment, and generates by-products containing hydrochloric acid with concentration higher than 30% and a sodium bisulfite solution. The invention belongs to the technical field of environmental protection.

Description

technical field [0001] The invention relates to a new method for absorbing tail gas produced by a chlorination method to produce trichloroacetyl chloride, through which hydrogen chloride, sulfur dioxide, disulfur dichloride, chlorine gas, etc. generated during the production of trichloroacetyl chloride can be separated and recovered, and the side effects The hydrochloric acid and sodium bisulfite sodium solution of more than 30% can be produced, which belongs to the technical field of environmental protection. Background technique [0002] Trichloroacetyl chloride is an important intermediate in the production of clopyridinate sodium and chlorpyrifos. The preparation steps of the chlorination method are: (1) chloroacetic acid waste liquid (mother liquor) reacts with chlorine gas in the presence of sulfur to generate mixed acid chlorides; (2) mixes Acyl chloride reacts with chlorine gas in the presence of pyridine to form trichloroacetyl chloride. The tail gas produced durin...

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Problems solved by technology

At present, the treatment method of some production enterprises is to directly absorb the tail gas with liquid caustic soda to obtain high-salt wastewater, which is diluted with a large amount of clean water and then undergoes biochemical treatment. This will not only fail to effectively recover the by-products in the production process of trichloroacetyl chloride, and produce a lot of waste water

In order to reclaim the by-products in the production process of trichloroacetyl chloride, some enterprises only adopt the method of adding absorption tanks to reclaim the mixed acid chlorides and part of sulfur monochloride in the tail gas, and then absorb hydrogen chloride to produce hydrochloric acid through the three-stage membrane absorption tower, but Since the tail gas entering the membrane absorption tower also contains a certain amount of sulfur monochloride, after entering the membrane absorption tower, the tail gas containing sulfur monochloride will react with water to precipitate sulfur and gradually block the tubes in the absorption tower, sometimes When the situation is serious, the three-effect membrane absorption tower will be stopped for maintenance every other week or so, so that the production cannot be continued, which seriously affects the output of trichloroacetyl chloride; in addition, due to the removal of hydrogen chloride, a Sulfur chloride also contains sulfur dioxide and other gases, resulting in the production of hydrochloric acid is a mixed acid, the product quality is not high, can not be well applied

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