Preparation method of N-methyl diethanolamine

Abstract

The invention relates to a manufacturing technology of organic amine, in particular to a preparation technological method of N-methyl diethanolamine. The preparation method comprises the following steps: respectively injecting ethylene epoxide and monomethylamine into heat exchangers for being cooled, and then injecting ethylene epoxide and monomethylamine into a mixer for being premixed; injecting the mixed raw material into a reaction kettle for reaction when the reaction pressure is kept at 4.5-5 MPa and the reaction temperature is kept at 120-135 DEG C; injection reaction liquid into a pressure-relief device to remove excess methylamine; injecting amine-removed substrate into a flash vaporization absorption tower for being processed so as to remove moisture and light component impurities; and finally utilizing a tertiary distillation and rectification column to separate N-methyl diethanolamine product. The preparation method solves the problems of overlong reaction time, low conversion rate, excessive side reaction and the like, which are caused by insufficient premixing in a conventional process, increases the MDEA (methyl diethanolamine) content from 70-80 percent in the original process to more than 90 percent, improves the reaction yield, lowers the unit consumption of raw materials, reduces energy consumption and also avoids environmental pollution.

Description

technical field [0001] The invention relates to the technical field of preparation of organic amine products, in particular to a preparation process of N-methyldiethanolamine. Background technique [0002] N-Methyldiethanolamine, commonly known as MDEA, is a colorless or yellowish viscous liquid with an ammonia smell, flammable and miscible with water and alcohol, slightly soluble in ether. MDEA is widely used in desulfurization and purification of oilfield gas and coal gas, natural gas, emulsifier and acid gas absorbent, acid-base control agent, polyurethane foam catalyst. CO2 and H2S produced in ammonia synthesis can be removed with the participation of activators. In addition, it can also be used as semi-finished products of insecticides, emulsifiers, fabric auxiliaries, intermediates of antitumor drug nitrogen mustard hydrochloride, catalysts for urethane coatings, fiber auxiliaries, etc. dry agent. [0003] At present, the preparation methods for producing N-methyldi...

AI Technical Summary

Problems solved by technology

[0003] At present, the preparation methods for producing N-methyldiethanolamine include the ring-opening reaction of ethylene oxide and methylamine, the methylation reaction of ethanolamine and methanol, the catalytic hydrogenation reaction of ethanolamine and formaldehyde, the substitution reaction of chloroethanol and methylamine, etc. There are many methods, but there are many problems in the production process, such as many reaction side reactions, low conversion rate, high unit consumption ratio, high temperature, low yield, etc.

[0004] For example: Chinese invention patent applications (publication numbers: CN101265195A, CN101506144A) all directly mix raw materials at normal temperature and pressure, and since the raw material methylamine is gaseous at normal temperature and ethylene oxide is liquid, the two are mixed into gas-liquid two Phase mixing, heterogeneous mixing will lead to insufficient mixing of raw materials, so only a large amount of monomethylamine can be used to ensure the full reflection of ethylene oxide

And the above reaction needs to be carried out at a higher temperature, resulting in long reaction time, low conversion rate, too many side reactions and other problems

Due to the small temperature difference between the bottom and the top of the rectification tower, and the vacuum degree is not high, there are still problems such as difficult separation of rectification products, low purity and poor quality of products.

In addition, there is no stripping section in the process, which cannot meet the requirements of continuous rectification and cannot realize continuous rectification

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