Method for preparation of D-fructose and D-mannose by simulated moving bed reactor

The invention discloses a method for preparation of D-fructose and D-mannose by a simulated moving bed reactor. The method comprises the steps of: 1) preparing a D-glucose aqueous solution, conducting filtration by a filter membrane to remove impurities from the solution; and 2) adding the solution obtained in step 1) into the simulated moving bed reactor, at the same time performing elution with pure water, when the simulated moving bed reactor reaches an equilibrium state, collecting a D-fructose solution at an extraction port of the simulated moving bed, and collecting a D-mannose solution at a raffinate port. The simulated moving bed reactor includes I-IV areas, wherein the I area and the III area are respectively composed of 1-6 chromatographic columns, and the II area and the IV area are respectively composed of 1-4 chromatographic columns. The method provided by the invention has mild reaction conditions and fast speed, the reaction system is simple and stable, the catalyst can be recycled, and the reaction cost and separation cost can be reduced by 30%.