Method for rectifying and separating methylal-methanol-water by adding salt composite extracting

Abstract

The salt adding composite extraction and rectification process of separating methylal-methanol-water mixed liquid includes the following steps: the first water extraction of the mixed liquid and extracting separation with 10-20 % salt-containing glycol in the proportion among material, water and salt-containing glycol being 1 to 0.3-1 to 0.5-1 at tower top temperature of 42-43 deg.c to obtain methylal of purity over 99.8úÑ in the tower top and the salt-containing mixed extractant as the effluent; the subsequent treatment of the salt-containing mixed extractant in a regeneration tower to obtain methanol of purity over 99.8úÑ in the tower top; treating the rest part in a methanol recovering tower for reuse; and using the salt-containing mixed extractant circularly. The present invention can separate methylal, methanol, formaldehyde and water effectively.

Description

technical field [0001] The present invention relates to a compound extraction and rectification process with salt addition, in particular to a process for separating methylal-methanol-water and methylal-methanol systems through compound extraction and rectification with salt addition, in particular to a method for the separation of methylal-methanol-water and methylal-methanol systems The invention relates to a compound extraction agent for compound extraction and rectification separation and a process method of compound extraction and rectification with salt addition. Background technique [0002] Methylal is mainly used in anion exchange resins, as well as solvents and special fuels. At present, it is generally produced by acid catalysis: methanol and formaldehyde are synthesized to form a mixed solution of methylal, methanol, formaldehyde and water. Due to the combination of methylal and methanol, Both formaldehyde and water form an azeotrope, and the mixed product is sep...

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Problems solved by technology

[0002] Methylal is mainly used in anion exchange resins, as well as solvents and special fuels. At present, it is generally produced by acid catalysis: methanol and formaldehyde are synthesized to form a mixed solution of methylal, methanol, formaldehyde and water. Due to the combination of methylal and methanol, Both formaldehyde and water form an azeotrope, and the mixed product is separated by precision rectification. The reflux ratio (R) is controlled at about 30:1, which not only consumes a lot of energy, but also can only obtain about 85% of methylal

At present, formaldehyde is removed by oxidation with alkaline hydrogen peroxide, methanol is removed by distillation with sodium metal, and then high-purity methylal is obtained by rectification. The separation process of this method is complicated and the energy consumption of the separation process is high.

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