METHOD OF SEPARATING EHYL-TERT-BUTHYL-ETHER AND ETHANOL

摘要

A method for separating ETBE and ethanol is described. This method comprises the following main stages: (1) Extraction of ethanol with water, the raffinate being ETBE saturated with water and the extract an ethanol/water mixture containing a small proportion of ETBE; (2) Concentration of the above mixture, the distillate being a mixture with a composition close to the ethanol/water azeotrope and containing a very small proportion of ETBE; (3) Heteroazeotropic distillation of this distillate in two coupled columns with a decanter at the head, this distillation using ETBE as azeotroping agent; the residue from the first column being approximately 99 mol % ethanol and the residue from the second column being virtually pure water, this water, as well as the water recovered during the concentration stage, being used as extraction solvent in Stage (1). The third stage of the method of the invention can constitute on its own a unit for dehydrating ethanol using ETBE as dehydrating agent. The method of separation of the invention can furthermore be integrated with a unit for the production of ETBE comprising the etherification by ethanol of the isobutene contained in a C4 steam cracking, catalytic cracking or isobutane dehydrogenation cut. The ethanol separated from the ETBE is then recycled to the etherification region.