Method for recovering nmp in gas by using high boiling point solvent

Abstract

A method for recycling N-methylpyrrolidone (NMP) from a gas by utilizing a high boiling point solvent, comprising: spraying a high boiling point solvent into an absorption apparatus from the top of the absorption apparatus, pumping an NMP-containing gas into the absorption apparatus from either the top or bottom of the absorption apparatus, allowing the gas and liquid phases to fully come into contact, removing NMP or NMP and water from the gas, thus acquiring a purified gas and a mixture containing NMP or containing NMP and water; and vacuum distilling the mixture containing NMP or containing NMP and water, thus separately recycling NMP and the high boiling point solvent. Furthermore, the recycled NMP and high boiling point solvent can be reused. The method allows highly efficient recycling of NMP in the gas and implements recycling and reuse of NMP and of the high boiling point solvent.

Description

technical field [0001] The invention specifically relates to a method for recovering N-methylpyrrolidone (NMP) in the gas produced in the process of lithium battery production by using a high boiling point solvent, and at the same time can remove the water therein, belonging to the field of NMP solvent recovery and gas purification . Background technique [0002] Demand for high-power, high-energy-density lithium-ion secondary batteries for automotive and compact power supplies is exploding. The basic components of a lithium-ion battery include a positive electrode, a negative electrode, an electrolyte, and a separator. In this battery manufacturing line, the N-methylpyrrolidone solvent (NMP), which is widely used and expensive, accounts for a large part of the battery manufacturing cost. During drying, all organic solvents turn into gas and are discharged into the atmosphere along with the heated air. It will cause a huge waste of raw materials. In addition, NMP is a tox...

AI Technical Summary

Problems solved by technology

If NMP is to be treated efficiently, it is necessary to require a large ventilation resistance of the device and a high power of the fan. In addition, a large amount of high-priced pure water needs to be provided, and the operating cost is high.

Moreover, such an absorption process will inevitably bring about the increase of moisture in the circulating gas, which is contrary to the high requirements for workshop humidity in the lithium battery production process

Moreover, the typical device of the existing cooling and condensation method is the rotary concentration adsorption, but a large amount of steam is required in the regeneration process of the adsorbent zeolite, and the energy consumption is high, which causes great cost pressure on the enterprise

[0005] In addition, some researchers have recently proposed a plan to capture NMP using low-boiling solvents such as water, ethanol, acetone, and propanol on the principle of a coagulant. The secondary VOC pollution that comes, and the inability to remove the moisture in the circulating gas, will even increase