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Method for recovering dichloromethane in acesulfame potassium synthesis

A technology of acesulfame potassium and dichloromethane is applied in the disproportionation separation/purification of halogenated hydrocarbons, organic chemistry and other directions, which can solve the problems of inability to directly apply, influence, and high recovery costs, and achieves improved production efficiency and improved rectification effect. , the effect of reducing labor intensity

Active Publication Date: 2020-12-29
NANTONG ACETIC ACID CHEM +1
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  • Abstract
  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

[0017] (3) Freeze dehydration: use the difference in the relative freezing point of dichloromethane and water to separate. For example, the patent CN101450890A freezes the water-containing dichloromethane to -2°C, the water freezes, and the dichloromethane remains in a liquid state. removal, this method needs to use additional refrigeration equipment to cool down, and the recovery cost is high
[0018] Through the above method, the water content of the recovered dichloromethane is still relatively high, so it cannot be directly applied
[0019] The most important indicator for the recovery of dichloromethane in the synthesis of acesulfame potassium is that the moisture must reach the standard, otherwise the reaction will be greatly affected; the recovery of DCM moisture in the above several treatment processes is 100 times higher than the current method, not applicable Recovery of Dichloromethane in the Synthesis of Acesulfame Potassium

Method used

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  • Method for recovering dichloromethane in acesulfame potassium synthesis

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] Dichloromethane and water-binding agent (a mixture of n-hexanol and m-xylene with a mass ratio of 7:3) that need to be recovered from the synthesis of acesulfame potassium are continuously fed into the rectification column from the tower at a mass ratio of 1:0.001. Carry out rough dehydration, continuously discharge materials from the tower kettle, control the pressure at the top of the tower to 0.5MPa, and the dichloromethane material whose moisture in the top of the tower reaches the specified index ≤ 0.1% enters the rectification tower ② from the top of the tower continuously for dehydration again, and control the pressure at the top of the tower to 1MPa , the top of the tower is connected to the water separator and condenser, the upper stratified water in the water separator is continuously discharged, and the lower dichloromethane layer is refluxed to the rectification tower ②Continue dehydration, the water in the tower kettle reaches the specified index ≤0.003% dich...

Embodiment 2

[0041] The dichloromethane and water-binding agent (a mixture of ethylene glycol and toluene each accounting for 50%) that need to be recovered from the synthesis of acesulfame potassium are continuously entered into the rectification tower ① from the tower for crude dehydration at a mass ratio of 1:0.005 , the tower kettle is continuously discharged, the pressure at the top of the tower is controlled to 0.3MPa, and the dichloromethane material with the moisture in the top of the tower reaching the specified index ≤0.1% enters the rectification tower ② for dehydration again, and the pressure at the top of the tower is controlled at 0.5MPa. The top is connected to the water separator and the condenser, the upper stratified water in the water separator is continuously discharged, and the lower layer of methylene chloride is refluxed to the rectification tower ② to continue dehydration, and the moisture in the tower kettle reaches the specified index ≤ 0.003% of the methylene chlor...

Embodiment 3

[0043] Dichloromethane and water-binding agent (a mixture of ethylene glycol and m-xylene each accounting for 50%) that need to be recovered from the synthesis of acesulfame potassium are continuously entered into the rectification tower ① from the tower at a mass ratio of 1:0.003 Coarse dehydration, continuous discharge from the tower kettle, control the pressure at the top of the tower to 0.5MPa, and the dichloromethane material whose moisture in the top of the tower reaches the specified index ≤0.1% enters the rectification tower ② from the top of the tower continuously for dehydration again, and controls the pressure at the top of the tower to 0.2MPa , the top of the tower is connected to the water separator and condenser, the upper stratified water in the water separator is continuously discharged, and the lower dichloromethane layer is refluxed to the rectification tower ②Continue dehydration, the water in the tower kettle reaches the specified index ≤0.003% dichloromethan...

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Abstract

The invention discloses a method for recovering dichloromethane in acesulfame potassium synthesis, wherein the method comprises the steps: 1) continuously feeding dichloromethane and a water-binding agent required to be recovered in acesulfame potassium synthesis into a rectifying tower from the tower for coarse dehydration, continuously discharging from a tower kettle, and continuously discharging a dichloromethane material in the tower top after reaching the standard; 2) continuously feeding a dichloromethane material into the rectifying tower from the tower top, dehydrating again, dividinginto an upper layer and a lower layer, continuously discharging an upper water layer, reflowing a lower dichloromethane layer to the rectifying tower, continuously dehydrating, and continuously discharging the dichloromethane material in the tower kettle after reaching the standard; and (3) continuously feeding the dichloromethane material into the rectifying tower from the tower to refine and remove high boiling point, controlling the reflux ratio of the rectifying tower to be (1-4):1, and continuously discharging finished dichloromethane from the tower top for continuous use. According to the invention, continuous crude dehydration is carried out, and then continuous rectification and continuous high-boiling removal are carried out, so that dichloromethane with the water content of lessthan or equal to 0.003% is prepared and used for preparing acesulfame potassium for reuse, and the method has the characteristics of simple process, low cost, low product water content, continuous whole process and the like.

Description

technical field [0001] The invention relates to the field of chemical gas recovery, in particular to a method for recovering dichloromethane in the synthesis of acesulfame potassium. Background technique [0002] Dichloromethane (DCM) [0003] Alias: Methylene dichloride; Methylene chloride; Methylene chloride; Methylene dichloride; Methylene chloride; Methylene chloride; Dichloromethylene; Methylene chloride [0004] English name: Dichloromethane(Methylene chloride); DEBLOCKING REAGENT; DEBLOCKREAGENT; DEBLOCK-TCA REAGENT; DETRITYLATING REAGENT; TRICHLOROACETIC ACID / DICHLOROMETHANE; TRICHLOROACETIC ACID IN DICHLOROMETHANE; [0005] Appearance properties: colorless transparent liquid with aromatic odor. [0006] CAS number: 75-09-2; [0007] Molecular formula:CH 2 Cl 2 ; [0008] Molecular weight: 84.93; [0009] Melting point: -97°C; [0010] Water solubility: insoluble in water; [0011] Density: 1.325g / ml at 25°C (lit.); [0012] Function and use: [0013] Dich...

Claims

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Application Information

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IPC IPC(8): C07C17/38C07C19/03
CPCC07C17/38C07C19/03
Inventor 庆九俞新南薛金全朱小刚刘芳
Owner NANTONG ACETIC ACID CHEM
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