Description:
Levulinic acid (LA) is considered a very interesting green, biomass derived versatile chemical intermediate with high application potential. Herein, MOF–5 was evaluated as a perspective support to synthesize heterogeneous catalysts with Brønsted acid sites and Lewis acid sites, via simple phosphotungstic heteropoly acid (HPAs) embedding. The MOF–5 supported HPAs catalyst showed high catalytic activity for the production of LA from glucose in green deep eutectic solvent (DES) media. The highest LA yield of 56.7 mol% was achieved under hydrothermal conditions at 130 °C for 3 h. By adjusting the ratio of Brønsted acid sites to Lewis acid sites, the reaction efficiency of the whole reaction chain (glucose → fructose → 5–HMF → LA) was promoted. Moreover, the interaction of the cationic species, DMF ions and the heteropoly anions, as well as the effect of hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) of DES on protonic acidity, were also considered to be the influence factors affecting the reactions