Method for preparing 1,4-butanediol by combining slurry-bed hydrogenation and fixed-bed hydrogenation

The invention discloses a method for preparing 1,4-butanediol by combining slurry-bed hydrogenation and fixed-bed hydrogenation. The method comprises at least one slurry-bed reactor and at least one fixed-bed reactor. The method comprises the following steps: a succinic acid aqueous solution with a mass concentration of 20+/-5% is mixed with hydrogen and then a formed mixture enters the slurry-bedreactor, and is brought into contact with a hydrogenation catalyst to carry out a hydrogenation reaction; a liquid phase material I from the slurry-bed reactor is filtered and then an obtained material is mixed with a gas phase material I from the slurry-bed reactor and then a formed mixture directly enters the fixed-bed reactor for a hydrogenation reaction; a gas phase material II and a liquid phase material II from the fixed-bed reactor enter a high-pressure separation tank together; and a gas phase material III from the high-pressure separation tank returns to the slurry-bed reactor, a liquid phase material III fr