Method for recovering N, N-dimethylacetamide solvent used in production of spandex

Abstract

The invention relates to a method for recovering an N, N-dimethylacetamide solvent used in the production of spandex. The method comprises the following steps of separating DMAC and acetic acid by virtue of an azeotropic distillation method, adding toluene into a mixed solvent of DMAC and acetic acid so that toluene and acetic acid form azeotrope having the lowest azeotropic temperature, carrying out distillation separation to respectively obtain high-purity DMAC and acetic acid, and adding a third solvent toluene in one time into the mixed solvent of DMAC and acetic acid so that toluene and acetic acid form azeotrope having the lowest azeotropic temperature and the purpose of separation of two solvents is achieved. By the used toluene entrainer, the azeotrope having the highest azeotropic temperature formed from DMAC and acetic acid can be well destroyed, high-purity DMAC and acetic acid products are separated, and the general problems existing in an spandex industry are solved; one the one hand, the environmental pollution caused by direct emissions is avoided; on the other hand, the separated DMAC and acetic acid are used again and thus the production cost is decreased, the energy consumption is saved and the social benefits are increased.

Description

technical field [0001] The invention relates to a process method for solvent recovery, in particular to separating DMAC (N,N-dimethylacetamide) and acetic acid mixed solvents in the spandex industry by adopting azeotropic distillation. Background technique [0002] N,N-Dimethylacetamide, referred to as DMAC, is an important organic chemical raw material, a pharmaceutical intermediate, and a solvent with excellent performance. A large amount of mixed solution of DMAC and acetic acid is produced in the production of spandex. How to recover DMAC and acetic acid economically and effectively is very important to improve the overall economic and social benefits of the enterprise and reduce pollution emissions. [0003] Since DMAC and acetic acid can form the highest azeotrope, and the azeotropic composition is DMAC: acetic acid = 76:24, it is impossible to completely separate the two through ordinary distillation. [0004] The conventional production process is to adopt the metho...

AI Technical Summary

Problems solved by technology

The main disadvantage of this process is: as the main solvent DMAC in the product

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