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Recovery method of N, N-dimethylacetamide

A technology of dimethylacetamide and a recovery method, which is applied in the field of chemical waste solvent recovery, can solve the problems of higher requirements for raw materials, blockage of membranes, limitation of universality of processing solvents, etc., and achieves the effect of process simplification

Pending Publication Date: 2020-05-05
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] Membrane separation technology is a new separation method that has emerged in recent years. Especially with the improvement of membrane production technology and research and development capabilities, the separation of many systems can be completed by membrane separation. The requirements for raw materials are relatively high, and the waste water solvent cannot contain fine particles such as inorganic salts and impurities, otherwise the membrane will be blocked and membrane pollution will be caused
Therefore, the universality of solvent treatment is limited, and it is not suitable for direct treatment of N,N-dimethylacetamide wastewater solvents produced in processes such as polymerization spinning and pharmaceutical synthesis.

Method used

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  • Recovery method of N, N-dimethylacetamide

Examples

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Comparison scheme
Effect test

Embodiment 1

[0029] A batch of waste water solvent containing 2% N,N-dimethylacetamide, the pH value is adjusted to between 6 and 8 by sodium carbonate, and then enters the distillation tower for preliminary concentration and removal of impurities. The operating pressure of the distillation tower is 1 atm. The reflux ratio is 0.5, and the temperature at the top of the tower is controlled at 100°C. The concentrated product is extracted through the side stream vapor phase, and the temperature of the extracted vapor phase material is 125° C., wherein the mass fraction of N,N-dimethylacetamide is 55%. After being pressurized to 4atm by the compressor, the temperature rises to 150°C, and it directly enters the membrane separation module for further dehydration and concentration. Four-stage membrane separation and dehydration are used, and the pressure on the permeate side is controlled at 1kPa. The obtained concentrate is sent to the refining tower for further dehydration. The operating pressur...

Embodiment 2

[0031] A batch of waste water solvent containing 5% N,N-dimethylacetamide is adjusted to a pH value between 6 and 8 by sodium carbonate, and then enters a distillation tower for initial concentration and removal of impurities. The operating pressure of the distillation tower is 1 atm. The reflux ratio is 0.5, and the temperature at the top of the tower is controlled at 100°C. The concentrated product is withdrawn through the side stream vapor phase, the temperature of the withdrawn vapor phase material is 122°C, and the mass fraction of N,N-dimethylacetamide is 50%. After being pressurized to 4atm by the compressor, the temperature rises to 149°C, and it directly enters the membrane separation module for further dehydration and concentration, using 5-stage membrane separation and dehydration, and the pressure on the permeate side is controlled at 1kPa. The obtained concentrate was sent to the refining tower for further dehydration. The operating pressure of the refining tower ...

Embodiment 3

[0033] A batch of waste water solvent containing 10% N,N-dimethylacetamide is adjusted to a pH value between 6 and 8 by sodium carbonate, and then enters a distillation tower for initial concentration and removal of impurities. The operating pressure of the distillation tower is 1 atm. The reflux ratio is 0.5, and the temperature at the top of the tower is controlled at 100°C. The concentrated product is extracted through the side stream vapor phase, and the temperature of the extracted vapor phase material is 128° C., wherein the mass fraction of N,N-dimethylacetamide is 60%. After being pressurized to 4atm by the compressor, the temperature rises to 152°C, and it directly enters the membrane separation module for further dehydration and concentration. Three-stage membrane separation and dehydration are used, and the pressure on the permeate side is controlled at 1kPa. The obtained concentrate is sent to the refining tower for further dehydration. The operating pressure of th...

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Abstract

The invention provides a recovery method of N, N-dimethylacetamide. The method comprises the following steps: enabling a waste solvent to enter a distillation tower, carrying out side line gas phase extraction, pressurizing, directly introducing an obtained product into a membrane separation unit, and dehydrating, so as to obtain an N, N-dimethylacetamide product. According to the invention, through a distillation tower side line gas phase extraction and membrane separation coupling mode, the process is simplified, the process energy consumption is reduced, especially the material heating process before membrane separation is saved, the process is green, the reuse rate is high, the waste discharge amount is small, and the industrialization is favorably realized. Meanwhile, the product purity of the obtained N, N-dimethylacetamide is higher than 99.9%, the moisture content is lower than 200 ppm, and the requirement for solvent application is completely met.

Description

technical field [0001] The present invention relates to the field of recovery of chemical waste solvents, in particular to a recovery method of N,N-dimethylacetamide waste solvents with rectification and membrane separation coupling process as the core, especially the technology of vapor phase extraction through the side line of distillation tower The process is simplified. Background technique [0002] N,N-Dimethylacetamide, DMAC for short, is a colorless and transparent commonly used non-protonated solvent, which can dissolve a variety of compounds, is completely miscible with water, ether, ketone, ester, etc., and has high thermal stability. , not easy to hydrolyze, low corrosion, low toxicity and so on. Therefore, it has a wide range of uses in many fields, such as in the fields of polymerization spinning, pharmaceutical synthesis, petroleum processing, leather and paint production, etc., try to act as a medium or solvent, especially for polyurethane resin and polyimide...

Claims

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Application Information

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IPC IPC(8): C07C231/24C07C233/05
CPCC07C231/24C07C233/05
Inventor 秦磊陈亮蔡立鑫
Owner CHINA PETROLEUM & CHEM CORP
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