To efficiently fractionate chloromethane and dimethyl ether each useful as e.g. a chemical raw material in high purity by treating a mixture of the dimethyl ether and chloromethane with methanol as extractant under specified conditions.
This production and fractionation of a mixture of dimethyl ether and chloromethane is conducted as follows: (i) methanol 1 is first reacted with an excess of HCl followed by further reaction of the resultant mixture with an excess of methanol 1, (ii) the resultant mixture is fed to a 1st distillation column 17 and water 25 is drawn from the bottom of the 1st distillation column 17, (iii) a mixture comprising methanol, the dimethyl ether and the chloromethane is drawn via the overhead of the 1st distillation column 17 and fed to an extractive distillation column 26, and methanol as extractant is then added to the upper part of the extractive distillation column 26, (iv) both the methanol and dimethyl ether are drawn via the bottom of the extractive distillation column 26, while the chloromethane is drawn via the overhead, and the resultant mixture thus drawn in this stage is then fed to a 2nd distillation column 39, and the methanol and the dimethyl ether are drawn via the bottom and overhead, respectively, followed by recirculating the methanol.
LEISTNER ERHARD (DE)
WENDEL WOLFGANG (DE)
