Post-treatment method of dihydroxy alcohol in byproduct residual liquor by technology for preparing ethanediol from coal

The invention provides a post-treatment method of dihydroxy alcohol in byproduct residual liquor by a technology for preparing ethanediol from coal. According to the method, the dihydroxy alcohol in the residual liquor is subjected to catalytic hydrogenation dehydration, so that the ethanediol is converted into ethanol and 1,2-butanediol is converted into butanol; and simple rectification is performed, so that the ethanol and the butanol are separated and collected. According to the method disclosed by the invention, a conventional high-energy-consumption rectification separation process performed on fraction in which the ethanediol and the 1,2-butanediol are main components is omitted, and through a hydrogenation dehydration reaction, azeotropic balance of the ethanediol and the 1,2-butanediol is effectively broken, and the purpose of extracting high-quality ethanol and butanol chemicals from the residual liquor is realized. The rectification energy consumption is reduced, the waste of resources is reduced,