A process for the preparation and fractionation of a mixture of dimethyl ether and chloromethane with water as extractant

摘要

Production and separation of a mixture of dimethyl ether (I) and chloromethane (II) comprises (a) reacting methanol (MeOH) with excess hydrogen chloride (HCl); (b) reacting the mixture from (a) with excess MeOH; (c) passing the mixture from (b) to an extractive distillation column (EDC); (d) adding water as extractant in the upper zone of the column; (e) discharging (II) at the top of the column; (f) discharging a mixture of water, MeOH and (I) from the sump and passing this to a first distillation column (DC-1); (g) discharging (I) from the top of this column; (h) discharging a mixture of water and MeOH from the sump; (i) feeding the mixture from (h) to a second distillation column (DC-2); (k) taking pure MeOH from the top of DC-2; (l) taking water from the sump of DC-2; and (m) passing the MeOH from stage (k) to stages (a) and (b).