Acetone-mediated glucose isomerization over a ZrO2-NC composite catalyst

The agglomeration-prone properties of metal oxide catalysts limit their catalytic efficiency in the isomerization of glucose to fructose. Herein, the hierarchical structure and abundant coordination groups of collagen fibers were used to anchor Zr 4+ , and a highly dispersed ZrO 2 -nitrogen-doped carbon (ZrO 2 -NC) composite catalyst was subsequently fabricated by calcination. For the catalytic glucose-to-fructose isomerization over ZrO 2 -NC, fructose was obtained in 41.3% yield and 85.3% selectivity in a water-acetone solvent at 120 °C for 10 min. The electron-deficient environment of ZrO 2 surface during charge transfer from ZrO 2 -to-NC layer benefited to preferentially adsorb glucose, which accelerated glucose isomerization and fructose desorption. The amphoteric catalyst triggered both proton transfer on the Bronsted base sites and the intramolecular hydride shift of glucose on the Lewis acid sites of ZrO 2 -NC in the mixed solvent. The latter isomerization mechanism depended on the presence of acetone, which lowered the energy barrier and increased fructose yield. The highly dispersed ZrO 2 in ZrO 2 -NC, featuring a hierarchical fiber structure, significantly enhanced the accessibility of the active sites. ZrO 2 -NC preferentially adsorbed glucose, and acetone lowered the reaction energy barrier, thereby promoting glucose isomerization to fructose. • ZrO 2 was dispersed and anchored within the hierarchical fiber structure of NC. • ZrO 2 -NC preferentially adsorbed glucose, accelerating isomerization. • Amphoteric ZrO 2 -NC triggered both proton transfer and intramolecular hydride shift. • Acetone reduced the energy barrier and improved fructose yield.