Compound cross-flow liquid-liquid extraction separation method of methylal-methanol azeotropic system

Abstract

The invention relates to a compound cross-flow liquid-liquid extraction separation method of a methylal-methanol azeotropic system. The raw material is a methylal-methanol azeotropic mixture, a compound extracting agent is formed by polylol, water and alkali in a certain proportion, and the raw material and the extracting agent carries out two-stage cross-flow liquid-liquid extraction on a methylal-methanol solution under a certain proportion; after layering separation, raffinate contains methylal with higher purity; extractive phases are the compound extracting agent and methanol; the raffinate contains methylal with higher purity and directly serves as product methylal after being distilled through a treating column; after the extractive phases are distilled by a regenerating column to remove the methanol, the compound extracting agent is recycled. The compound extracting agent of the prioritization scheme is the mixture of glycerine, water and potassium hydroxide, and the mass ratio is 9:0.9:0.1. Compared with the traditional methods, the invention has more obvious methanol removing effect, higher product purity, higher recovery ratio and lower energy consumption. Due to the fact that the compound extracting agent can be recycled in the whole process, the production cost is lower, and the environment cannot be polluted.

Description

technical field [0001] The invention relates to a chemical separation method, in particular to a compound cross-flow liquid-liquid extraction separation method of a methylal-methanol azeotropic system Background technique [0002] Methylal has excellent physical and chemical properties, that is, good solubility, low boiling point, and good compatibility with methanol, and can be widely used in cosmetics, medicines, household products, industrial automotive supplies, insecticides, leather polishes, cleaning agents In the rubber industry, paint, ink and other products, because methylal has good degreasing ability and volatility, it can replace F11 and F113 and chlorinated solvents as a cleaning agent, so it is a substitute for Freon and reduces volatile organic compounds ( VOCs) emissions, environmental protection products that reduce air pollution. The synthetic method of methylal mainly contains dichloromethane method, dimethyl sulfoxide method, calcium chloride method, aci...

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Problems solved by technology

The synthetic method of methylal mainly contains dichloromethane method, dimethyl sulfoxide method, calcium chloride method, acid catalysis method, carbon monoxide heterogeneous catalysis and chloramphenicol by-product method, in above-mentioned method, dichloromethane method, two Methyl sulfoxide method and carbon monoxide heterogeneous catalysis are limited because the catalyst is unstable to acid and carbon monoxide or the yield is low; calcium chloride method is not conducive to industrial production because of long reaction time and difficult post-treatment; currently, chlorotoxin is generally used Preparation of methylal by by-product method and acid catalysis method

Regardless of the acid-catalyzed method or the chloramphenicol by-product method, the product after the reaction is a mixture of methylal-methanol, and there are subsequent separation problems. Due to the azeotrope between methylal and methanol, the azeotropic point is 41.85 ° C, and it contains methylal. Aldehyde 91.8%, so it is difficult to obtain high-purity methylal products by ordinary distillation

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