Using Sub/Supercritical CO2 as 'Phase Separation Switch' for the Efficient Production of 5-Hydroxymethylfurfural from Fructose in an Ionic Liquid/Organic Biphasic System

摘要

The formation of a series of side products causes low yield and difficult separation in 5-hydroxymethylfurfural (HMF) preparation. To overcome these problems, a novel switchable biphasic reaction/separation coupling system is proposed for the efficient preparation of HMF from fructose. The miscible ionic liquid (IL)/organic solvent is adjusted to two phases with CO2 as the "phase separation switch". Reactants and catalyst are mainly enriched in the IL phase and the produced HMF is continuously extracted into the organic solvent phase. This leads to 84% yield of HMF and the mass ratio of HMF in the organic solvent phase to the IL phase of 1.3:1 in a biphasic system. Comparing to several commonly used systems and a biphasic system, the switchable biphasic reaction/separation coupling system is more efficient for HMF preparation. On the basis of the results, a biphasic consecutive process for HMF preparation is also proposed, which is an effective production process through recycling of the inexpensive and abundantly available solvents and CO2. It is expected that such a system may provide more applications for efficient reactions and separations in ILs.