TECHNICAL DESCRIPTION

Fructose finds already various applications in the food industry. The current industrial process is based on immobilized enzymes. For the production of platform molecules from biomass such as 5-HMF, fructose is believed to become an important intermediate, since this ketohexose is more reactive than glucose, an aldohexose. However, glucose is more available and cheaper than fructose, this makes glucose the preferred starting feedstock to produce 5-HMF.
Thus, this justifies the search for an alternative glucose-fructose isomerization process which would be as selective as the enzymatic one but faster and more robust. The present invention describes a method to isomerize glucose into fructose in the presence of solid bases and an integrated method to produce 5-HMF from glucose. The more active solid base described in the invention are simple or mixed oxide containing lanthanides. Compositions close to the thermodynamic equilibrium of the glucose-fructose isomerization reaction are achieved in short reaction time. The solid bases of the present invention are efficient to isomerize glucose in fructose in aqueous solution and do not need any pretreatment before the reaction, according to their resistance towards irreversible atmospheric CO2 adsorption.
The present invention reports also an integrated method to produce 5-HMF which combines a first isomerization step performed in water in the presence of the solid base of the invention and a second step where the fructose is dehydrated into 5-HMF after addition of a sufficient amount of carboxylic acid to the reaction medium.

INDUSTRIAL APPLICATIONS

Applications include:
1) the conversion of glucose into fructose using alternative process to the enzymatic one, which is more rapid and robust.
2) An economically viable method to produce 5-HMF using glucose as raw material.