Dimethyl ether (DME) synthesis

Abstract

Systems and processes for producing dimethyl ether from a low-quality crude methanol include purifying a crude methanol stream including methanol, water, acetone, and methyl formate. The crude methanol is contacted with a glycol, a glycerol, or a mixture of glycols in an azeotropic distillation column to recover a first overhead stream comprising the acetone and methyl formate and a first bottoms stream comprising the glycol or glycerol, water, and methanol. The first bottoms stream is then separated, in some embodiments, in a dividing wall distillation column to recover a second overhead stream comprising methanol and water, a second bottoms stream comprising the glycol or glycerol, and a side draw stream comprising water. The resulting high purity methanol stream is fed to a reaction system configured for converting the methanol to dimethyl ether and to recover a reaction effluent comprising dimethyl ether, methanol, and water.

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