A highly efficient hydrotalcite/1-butanol catalytic system for production of the high-yield fructose crystal from glucose

Abstract

Catalytic isomerization of glucose to fructose is a key step for the synthesis of bioplastics and biofuels as well as sweeteners. In this study, a record fructose yield of greater than 50% with selectivity exceeding 80% was obtained from glucose concentration of 10 wt.% by adopting a 1-butanol/hydrotalcite catalytic system. In this novel process, Mg2+ leaching from hydrotalcite, which is an important issue when utilizing hydrotalcite for glucose isomerization in aqueous solution, was negligible during the reaction. NMR study confirmed that the absence of deuterium at the C-1 position of the fructose product as well as C-2 position of glucose-2-d clearly supports the base-catalyzed deprotonation of the C-2 position in glucose. Also, DFT calculations supported the selective formation of fructose from glucose over hydrotalcite surface in 1-butanol than other solvents. Notably, after glucose isomerization the highly-pure glucose (91%) and fructose crystals (95%) were recovered easily from 1-butanol solvent by subsequent cooling and filtration without requiring chromatographic separation. Therefore, the hydrotalcite/1-butanol catalytic system is simple, inexpensive, and green process for the high-yield fructose production from glucose when compared with current industrial procedures that rely on enzymatic isomerization reactions and chromatographic separations.