Preparation method for polyol and application of polyol in making polyurethane

A preparation method of a polyol, comprising the following steps of:

• (1) dissolving 2,3-epoxybutane and an acid catalyst in an inert solvent to obtain a solution A;
• dissolving triethylene glycol in an inert solvent to obtain a solution B;
• and dissolving epoxy vegetable oil in an inert solvent to obtain a solution C;
• (2) respectively and simultaneously pumping the solution A and the solution B into a first micromixer in a microchannel reaction device for mixing, and then introducing the mixture into a first microreactor for reaction to obtain a reaction solution containing a hydroxyl compound;
• (3) respectively and simultaneously pumping the solution C and an effluent of the first microreactor into a second micromixer in the microchannel reaction device for mixing while carrying out step (2), and then introducing the mixture into a second microreactor for reaction to obtain a reaction solution containing a vegetable oil polyol, and then separating the solution to obtain the vegetable oil polyol;
• and
• (4) dissolving the vegetable oil polyol obtained in step (3) in an inert solvent to obtain a solution D;
• dissolving epoxypropane and an alkaline catalyst in an inert solvent to obtain a solution E;
• and respectively and simultaneously pumping the solution D and the solution E into a tank reactor for reaction, thereby obtaining the polyol;
• wherein the polyol is capable of being used for preparing a polyurethane.