Composite polymerization inhibitor for extracting and rectifying conjugated diene with dimethylformamide and use method

A technology of dimethylformamide and conjugated diene, which is applied in the field of composite polymerization inhibitor for N,N-dimethylformamide extractive and rectified conjugated diene, can solve the problem that the content of sodium nitrite cannot be effectively Control, polymerization inhibition effect cannot be guaranteed, liquid flooding and processing capacity decline, etc., to achieve good polymerization inhibition effect, facilitate accurate quantitative delivery, and improve solubility.

Active Publication Date: 2013-05-01
NINGBO JINHAI CHENGUANG CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Undissolved sodium nitrite deposits at the solvent feed plate and downcomer, accumulating over time, clogging the tray and downcomer, resulting in flooding and reduced processing capacity
On the other hand, sodium nitrite is added intermittently, the content of sodium nitrite in the circulating solvent is high when it is just added, and then decreases, the content of sodium nitrite cannot be effectively controlled, and the polymerization inhibition effect cannot be guaranteed when the content is low
Although this way of adding sodium nitrite has disadvantages such as poor solubility, easy tower blockage, ineffective control of content, and large content fluctuations, due to its unique inhibitory effect, no suitable substitute has been found so far.

Method used

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  • Composite polymerization inhibitor for extracting and rectifying conjugated diene with dimethylformamide and use method
  • Composite polymerization inhibitor for extracting and rectifying conjugated diene with dimethylformamide and use method
  • Composite polymerization inhibitor for extracting and rectifying conjugated diene with dimethylformamide and use method

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Experimental program
Comparison scheme
Effect test

Embodiment 1 to Embodiment 3

[0027] Preparation method of component A and component B:

[0028] Prepare Part A and Part B separately.

[0029] Component A of a mixed solution obtained by dissolving 4-Hydroxy-TEMPO, 2-hydroxyethylamine and auxiliary agents in toluene. Place Component A in the Component A tank.

[0030] Sodium nitrite is dissolved in water to obtain component B. Place Component B in the Component B tank.

[0031] The preparation concentrations of component A and component B are shown in Table 1.

[0032] Table 1 embodiment component A, component B preparation concentration

[0033]

[0034] The above-mentioned polymerization inhibitor is applied to the dimethylformamide extractive distillation isoprene process, and this embodiment is applied to the second extractive distillation system of the C5 separation device. The second extractive distillation system is composed of a second extractive distillation tower, a desorption tower and a vacuum desorption tower. It further purifies the ...

Embodiment 1

[0059] In the initial stage of device feeding and start-up, due to the existence of corrosion, surface active centers in the equipment, and high oxygen content in dead corners, etc., a relatively high content of polymerization inhibitor is required for inhibition, and the consumption of polymerization inhibitor is also large. Therefore, polymerization inhibition The preparation concentration is high. In component A, the concentration of 4-Hydroxy-TEMPO is 18%, the concentration of 2-hydroxyethylamine is 36%, and the concentration of isopropanol is 12%. Since isopropanol has a solubilizing effect, 2-hydroxyethylamine also has a solubilizing effect effect, all 4-Hydroxy-TEMPO dissolves. The sodium nitrite content of component B is 28%, and the concentration is correspondingly higher.

[0060] During the first 3 months of start-up, there was no clogging of component A pipeline. The average polymer content in the circulating solvent is 0.032%, which is at a relatively low level,...

Embodiment 2

[0062] In seasons when the temperature is higher than 18°C, the concentration of component A4-Hydroxy-TEMPO is 15%, and the concentration of 2-hydroxyethylamine is 30%. Since the temperature is not low, the amount of auxiliary agent isopropanol can be added a little less, and the concentration is 7.5%. . Component B sodium nitrite content is 20%.

[0063] During the 3 months of the observation period, no clogging of component A pipeline was observed. The average polymer content in the circulating solvent was measured to be 0.027%, indicating that the polymerization inhibition effect is good and the amount of polymer generated is small. The operation of the second extractive distillation column was stable, the pressure difference was stable, and the pressure difference changed little, indicating that sodium nitrite was not deposited on the solvent feed plate and downcomer.

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Abstract

The invention relates to a composite polymerization inhibitor for extracting and rectifying conjugated diene with dimethylformamide, and a use method. The composite polymerization inhibitor is characterized in that the inhibitor comprise a component A and a component B, wherein the component A is a mixed solution prepared by dissolving 4-hydroxyl-2,2,6,6-tetramethyl piperidine-1-oxygen, 2-hydroxyl ethylamine and an adjuvant in toluene; a weight concentration of 4-hydroxyl-2,2,6,6-tetramethyl piperidine-1-oxygen in the mixed solution is 10-20%; a weight concentration of 2-hydroxyl ethylamine in the mixed solution is 20-40%; a weight concentration of the adjuvant in the mixed solution is 5.0-20%; the adjuvant is alcohol, propyl alcohol, isopropanol, isobutanol, tertiary butanol or phenethyl alcohol; and the component B is a sodium nitrite aqueous solution with a weight concentration of 10-30%. The components of the polymerization inhibitor have synergistic effects, the polymerization inhibitor has a good polymerization inhibition effect, is not deposited in a tower, is convenient and accurate to use, is not crystallized and is freeze-resistant in a low temperature environment, and the consumption of a solvent is low.

Description

technical field [0001] The invention relates to the field of polymerization inhibition in the production process of polymer monomers, in particular to an antifreezing and anti-blocking N,N-dimethylformamide composite polymerization inhibitor for extracting and rectifying conjugated diolefins and a use method thereof. Background technique [0002] The cracked carbon five contains isoprene, and the cracked carbon four contains butadiene, and isoprene and butadiene are monomers for making rubber. The extraction and rectification process is usually used to separate the isoprene in the cracked C5 and the butadiene in the cracked C4. Commonly used extraction and distillation solvents include N,N-dimethylformamide (hereinafter referred to as dimethylformamide or DMF), acetonitrile, and N-methylpyrrolidone. Due to the good selectivity of DMF and the high purity of monomers, most processes Using dimethylformamide. [0003] Conjugated dienes such as isoprene and butadiene are very a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C7/20C07C7/08C07C11/12C07C11/18
Inventor 赵全聚
Owner NINGBO JINHAI CHENGUANG CHEM
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