Process for the preparation of pure dimethyl ether

Abstract

Process for the preparation of dimethyl ether product by catalytic conversion of synthesis gas to dimethyl ether comprising the steps of contacting a stream of synthesis gas comprising carbon dioxide in a dimethyl ether synthesis step in one or more reactors and with one or more catalysts being active in formation of methanol and dehydration of methanol to dimethyl ether, to form a product mixture comprising the dimethyl ether and carbon dioxide, washing the product mixture in a scrubbing zone with a liquid solvent being rich in dialkyl ether of a polyalkylene glycol and thereby dissolving carbon dioxide and dimethyl ether in the liquid solvent, treating the liquid solvent being withdrawn from the scrubbing zone sequentially in separation zone to effect desorption of the dissolved carbon dioxide and to recover a substantially pure dimethyl ether product and the liquid solvent in its substantially lean form and recycling the lean liquid solvent to the scrubbing zone.