Process for the preparation and fractionation of a mixture of dimethyl ether and chloromethane with water as extractant
AssigneeHoechst Aktiengesellschaft
InventorsPeter Roth, Erhard Leistner, Hans Haverkamp
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Abstract
A process for the preparation and fractionation of a mixture of dimethyl ether and chloromethane by extractive distillation with water as extractant. The mixture is prepared by reacting methanol with hydrogen chloride. It is then subjected to an extractive distillation with water as extractant, resulting in chloromethane as top product. In the next step, the dimethyl ether is removed by distillation and, in another step, the extraction water is separated from the methanol which is still present.
Claims14
A process for the preparation and fractionation of a mixture of dimethyl ether and chloromethane, which comprises
- a) reacting methanol with an excess of HCl,
- b) reacting the mixture obtained in step a) with an excess of methanol,
- c) feeding the mixture obtained in step b) to an extractive distillation column,
- d) adding water as extractant in the upper part of the extractive distillation column,
- e) taking off chloromethane from the top of the extractive distillation column,
- f) taking off a mixture of water, methanol and dimethyl ether from the bottom of the extractive distillation column and feeding it to a first distillation column,
- g) taking off dimethyl ether from the top of the first distillation column,
- h) taking off a mixture of water and methanol from the bottom of the first distillation column,
- i) feeding the mixture obtained in step h) into a second distillation column,
- k) taking off methanol at the top of the second distillation column,
- l) taking off water at the bottom of the second distillation column,
- m) feeding the methanol obtained in step k) into the reactions mentioned in steps a) and b).
Dependencies are inferred from the claim text.