Method for preparing formic acid through hydrothermal reduction of CO2 by carbohydrate biomass

The invention discloses a method for preparing formic acid through hydrothermal reduction of CO2 by carbohydrate biomass and relates to a process that the CO2 is reduced into the formic acid by utilizing the carbohydrate biomass and the carbohydrate biomass is converted into lactic acid, acetic acid, the formic acid and other chemical raw materials with high added value. The process comprises the following steps: firstly, mixing the CO2, water, alkali and the carbohydrate biomass; secondly, reacting for 20 to 300 minutes under the condition that the temperature is between 150 and 400 DEG C, the pressure is between 2 and 25MPa and pH value is between 6 and 13, wherein the CO2 is reduced into the formic acid by the carbohydrate biomass and the carbohydrate biomass is also converted into the lactic acid, the acetic acid, the formic acid and the like; and finally, performing decompression, distillation and separation according to different boiling points of the formic acid, the acetic acid and the lactic acid to obtain the formic acid, the acetic acid and the lactic acid. The method realizes the CO2 recycling and the carbohydrate biomass recycling; and as a reducing agent for reducing the CO2 is renewable resource of the carbohydrate biomass which is obtained through photosynthesis of the CO2 and H2O, the method indirectly utilizes solar energy.