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CN-122006629-A - Argon hierarchical replacement method for n-butyllithium synthesis

CN122006629ACN 122006629 ACN122006629 ACN 122006629ACN-122006629-A

Abstract

The invention relates to the technical field of argon hierarchical replacement, in particular to an argon hierarchical replacement method for n-butyllithium synthesis. The method comprises the steps of arranging an air-placing cavity between adjacent reaction kettles, controllably communicating the air-placing cavity with an air outlet of a preceding reaction kettle and an air inlet pipeline of a subsequent reaction kettle through a control valve group, starting pretreatment equipment (branch pipes) to introduce argon gas into a single kettle, removing the mixed gas in the blind area of the pipeline, controlling the time sequence and the flow of the argon gas at the upstream and downstream air inlets to form a stable pressure gradient, directionally pushing the mixed gas in the kettle to the air-placing cavity, introducing the mixed gas of the preceding air-placing cavity into the subsequent kettle for repeated replacement, and finally discharging the mixed gas from the tail end.

Inventors

  • WANG LI
  • ZHANG KAILUN
  • CAO ENQING
  • ZHOU ZHENQIU

Assignees

  • 江苏新瑞药业有限公司

Dates

Publication Date
20260512
Application Date
20260409

Claims (10)

  1. 1. An argon staged replacement method for synthesizing n-butyllithium is characterized by comprising the following steps: S1, constructing a system, namely arranging an air-placing cavity between two adjacent reaction kettles to be replaced, and controllably communicating the air-placing cavity with an air outlet of a preceding-stage reaction kettle and an air inlet pipeline of a subsequent-stage reaction kettle through a control valve group; S2, forming and replacing pressure gradients, namely, aiming at a reaction kettle, firstly, opening at least one branch pipe of the reaction kettle and introducing argon to remove pipeline blind areas, and then, forming a stable pressure gradient which decreases from upstream to downstream in the reaction kettle by cooperatively controlling the introducing time sequence and the flow rate of the argon of a downstream air inlet (100 a), a middle-stream air inlet (101 a) and an upstream air inlet (102 a), so as to directionally push the gas in the reaction kettle into a gas-placing cavity communicated with the reaction kettle; S3, gas recursion and sweep, namely introducing the mixed gas temporarily stored in the pre-stage air placing cavity into an upstream air inlet of a post-stage reaction kettle, and repeatedly executing the step S2 on the post-stage reaction kettle; S4, combined purging, namely after the mixed gas is completely discharged, keeping the air inlets of all the reaction kettles open, and simultaneously introducing argon to perform combined purging on the whole system for 3-10 minutes.
  2. 2. The method for fractional substitution of argon for n-butyllithium synthesis according to claim 1, wherein the pressure gradient is specifically 16-20kPa upstream, 13-17kPa midstream and 10-14kPa downstream.
  3. 3. The method for fractional substitution of argon for n-butyllithium synthesis according to claim 1, wherein in S2, for any one reaction vessel, the specific step of forming the pressure gradient comprises: S2.1, opening at least one branch pipe of the reaction kettle and introducing argon so as to clear a pipeline blind area; S2.2, opening a downstream air inlet (100 a) and a midstream air inlet (101 a) of the reaction kettle so as to establish a main air flow upwards from the bottom of the reaction kettle; s2.3, opening an upstream air inlet (102 a) of the reaction kettle, and forming and maintaining the stable pressure gradient by cooperatively adjusting the flow rates of the downstream air inlet (100 a), the middle upstream air inlet (101 a) and the upstream air inlet (102 a).
  4. 4. The method for classifying and replacing argon for synthesizing n-butyllithium according to claim 1, wherein the volume of the gas-filled cavity is 5% -15% of the volume of the connected reaction kettle.
  5. 5. The method for classifying and replacing argon for synthesizing n-butyllithium according to claim 4, wherein the downstream air inlet (100 a), the middle air inlet (101 a) and the upstream air inlet (102 a) are respectively positioned at the bottom, the middle and the top of the reaction kettle.
  6. 6. The method for fractional substitution of argon for n-butyllithium synthesis according to claim 1, wherein the duration of the pressure gradient and substitution for a single reaction vessel in S2 is 5-15 minutes.
  7. 7. The method for classifying and replacing argon for synthesizing n-butyllithium according to claim 1, wherein an oxygen content sensor is arranged at the inlet or outlet pipeline of the gas-filled cavity, and when the detected oxygen content is higher than a preset threshold value, the replacement time of the previous reaction kettle for forming the pressure gradient is automatically prolonged.
  8. 8. The method for classifying and replacing argon for synthesizing n-butyllithium according to claim 3, wherein in S2.1, the branch pipe comprises a discharge pipe (104), a branch pipe II (105) and a branch pipe I (103) which are arranged at one side of a valve body of the discharge pipe, and the operation of introducing argon to clear the blind area of the pipeline lasts for 1-3 minutes.
  9. 9. The method according to claim 1, wherein the positive pressure of 5 to 10kPa is maintained in the whole displacement system during the combined purging in S4.
  10. 10. The method for fractional replacement of argon for n-butyllithium synthesis according to claim 7, wherein the preset threshold is 100ppm, and the replacement system extends the replacement time of the previous reactor by 20% -50% when the oxygen content sensor detection value is higher than the threshold.

Description

Argon hierarchical replacement method for n-butyllithium synthesis Technical Field The invention relates to the technical field of argon hierarchical replacement, in particular to an argon hierarchical replacement method for n-butyllithium synthesis. Background N-butyllithium (n-BuLi) is a polymerization initiator widely used in the production of lithium-based polymers, and is industrially used mainly in the production process of products such as thermoplastic elastomer SBS, SIS, SEBS, low cis-polybutadiene rubber, solution polymerized styrene-butadiene rubber, and K-resin. In addition, n-butyllithium is also widely applied to industries such as fine chemical engineering, medicines and the like. At present, the production capacity of a polymer device using n-butyllithium as an initiator in China exceeds 21 ten thousand t/a. At present, the production device of n-butyl lithium is that under the protection of inert gas, metallic lithium is heated to above the melting point in white oil to be completely melted, then the molten metallic lithium is stirred and dispersed at high speed to form fine lithium sand with extremely high activity, and then the fine lithium sand reacts with n-butyl chloride in cyclohexane or a solvent system of n-hexane to prepare n-butyl lithium solution, and the solution is filtered and separated to obtain n-butyl lithium. In a multiple reactor cascade system for continuous production of n-butyllithium, creating and maintaining an oxygen-free, water-free, clean environment faces serious challenges presented by the inherent structure of the system. The system is internally integrated with various branch pipes, instrument interfaces, sampling ports and connecting elbows to meet the requirements of multiple processes such as lithium melting, dispersing, reacting and filtering, and a complicated pipeline network is formed. These complex structures create a large amount of difficult-to-reach geometric dead space outside the system body, where conventional replacement techniques, whether simple end-blow, end-draw, or vacuum-recharge inert gas, are struggled. The gas flow generated by the former naturally tends to be the main channel with the least resistance, and residual gas in the dead zone cannot be effectively swept and removed at all, so that the areas become hidden dangers of continuously polluting a reaction system, and the effect of removing static gas in the dead zone and a molecular adsorption layer attached to the surface of a huge inner wall is limited. Under the continuous production scene of multi-kettle series connection, the independent and sequential replacement of each reaction kettle is low in efficiency and consumes a great amount of inert gas, a connecting pipeline between kettles is easy to become a replacement blind area, if the treatment is improper, residual impurities can be diffused among kettles, linkage cross contamination is caused, and the quality of n-butyl lithium products is endangered. Disclosure of Invention The invention provides an argon grading replacement method for synthesizing n-butyllithium, which is characterized in that an air placing cavity is arranged between adjacent reaction kettles of a multi-kettle serial system, and the air inlet timing and flow of the downstream, midstream and upstream air inlets of each reaction kettle are cooperatively controlled, so that a stable directional pressure gradient is formed inside the reaction kettle, thus the original gas in the system and the mixed gas formed in the replacement process are gradually and directionally pushed into the air placing cavity for temporary storage, and are used as an air inlet source for replacing the next reaction kettle, the effective sweep of a geometric dead zone in the whole complex pipeline system is finally realized, the cross contamination problem under the multi-kettle serial condition is fundamentally avoided, the replacement efficiency is improved, the consumption of inert gas is greatly reduced, and the problems in the background technology are solved, namely: The prior art can not overcome the problems of dead zone replacement and cross contamination inherent in the complex structure of the multi-kettle serial system, so that the inert gas replacement efficiency is low and the effect is not thorough. In order to achieve the above purpose, the argon staged replacement method for synthesizing n-butyllithium comprises the following steps: S1, constructing a system, namely arranging an air-placing cavity between two adjacent reaction kettles to be replaced, and controllably communicating the air-placing cavity with an air outlet of a preceding-stage reaction kettle and an air inlet pipeline of a subsequent-stage reaction kettle through a control valve group; S2, forming and replacing pressure gradients, namely, aiming at a reaction kettle, firstly, opening at least one branch pipe of the reaction kettle and introducing argon to clear a pipeline blind area, and then, formin