The invention relates to a method for separating an n-
propyl formate-n-propyl
alcohol-water mixture by liquid-
liquid phase separation
coupling extractive distillation, which comprises the following steps of: dividing a
raw material into a water phase and an organic phase by using a
phase splitter based on the heterogeneous characteristic of an azeotropic
system, and carrying out four-
tower operation on a rectifying
tower (C1), a rectifying
tower (C2), a rectifying tower (C3) and a rectifying tower (C4) to obtain an n-
propyl formate-n-propyl
alcohol-water mixture. The efficient separation of the n-
propyl formate-n-propyl
alcohol-water mixture is realized. After separation, the
molar fraction of n-propyl
formate is greater than 99.99%, the
molar fraction of n-propyl alcohol is greater than 99.99%, and the
molar fraction of water is greater than 99.99%. The method provided by the invention realizes high-efficiency and low-energy-consumption separation of the n-propyl
formate-n-
propanol-water azeotropic mixture, and has
economic benefits and environmental friendliness.