Salt-Promoted Glucose Aqueous Isomerization Catalyzed by Heterogeneous Organic Base

Abstract

Effective isomerization of glucose to fructose is a crucial step for 5-hydroxymethylfurfural production from lignocellulose. The present study investigated polystyrene-supported organic bases with varied structural properties for aqueous isomerization of glucose. The results indicate that the heterogeneous organic bases can achieve approximately 30% fructose yields at 120–140 °C. As heterogeneous catalysts, they are generally less efficient than homogeneous organic bases and can lose catalytic activity during recycling likely from thermal-induced byproducts. However, the addition of neutral salt made the heterogeneous organic bases as efficient as homogeneous organic bases, achieving approximately 41% maximum fructose yields at 80–100 °C; and improved the reusability allowing the heterogeneous organic bases to be reused for at least four times without significant loss of catalytic activity.