Method for separating diethoxymethane and ethanol by glycerol and water multi-stage countercurrent liquid-liquid extraction

Abstract

The invention relates to a method for liquid-liquid extracting and separating diethoxymethane (DEM) and ethanol by adopting glycerin and water in a way of multi-stage counter current, comprising the steps: polylol and the water are taken as extracting agent for liquid-liquid extracting the DEM and the ethanol solution; after extraction and hierarchical separation, extract phase is processed by rectifying, and then solvent can be recycled; the faffinate contains over 99.7% of DEM. The method has the prioritization scheme that liquid-liquid extraction with multi-stage counter current is adopted; the raw material DEM and the ethanol solution are sent to an extracting tower and contacted with extracting agent propanetriol and water which flow into the extracting tower along the reverse direction, the faffinate passes through a static hierarchical section 2 (the liquid stops at the section for more than 10min), and the faffinate contains more than 99.7% of DEM; the mixed liquid of extracting agent at the bottom of the extracting tower is separated by a rectifying tower, and ethanol water solution can be obtained on the top of the rectifying tower. The method can effectively separate the DEM and the ethanol solution, and the purity and one-time yield of the DEM respectively reaches over 99.7% and 98% after separation.

Description

technical field [0001] The invention relates to a liquid-liquid extraction process for chemical production, in particular to a method for separating diethoxymethane (DEM) and ethanol by using glycerin and water multistage countercurrent liquid-liquid extraction. Background technique [0002] Diethoxymethane (DEM) is an important solvent and pharmaceutical intermediate, and it is generally produced by acid catalysis and chloramphenicol by-product method. Regardless of the acid catalysis method or the chloramphenicol by-product method, precision rectification is often used in the separation process. Since the boiling point of DEM in the product is close to the azeotropic point of ethanol and water, the reflux ratio (R) of the rectification method is controlled at about 30:1, not only consumes a lot of energy, but also can only get about 95% of DEM. At present, someone in China proposes to use glycerin to extract and separate DEM, ethanol and water. After separation, the DEM c...

AI Technical Summary

Problems solved by technology

Regardless of the acid catalysis method or the chloramphenicol by-product method, precision rectification is often used in the separation process. Since the boiling point of DEM in the product is close to the azeotropic point of ethanol and water, the reflux ratio (R) of the rectification method is controlled at about 30:1, not only consumes a lot of energy, but also can only get about 95% of DEM

At present, someone in China proposes to use glycerin to extract and separate DEM, ethanol and water. After separation, the DEM content reaches 99%, and the ethanol content reaches 0.8%. To obtain DEM above 99.7%, further rectification is required, and the reflux ratio reaches more than 8:1. A process consumes a lot of energy

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