Cr/MCM-22 catalyst for the synthesis of levulinic acid from green hydrothermolysis of renewable biomass resources

The novel Cr-loaded MCM-22 zeolite (Cr/MCM-22) was successfully synthesized, fully characterized, and applied as a heterogeneous catalyst for the transformation of biomass-derived materials (glucose, sucrose, cellulose, starch, agricultural residues, and other municipal wastes) into levulinic acid via hydrothermolysis. The novel Cr/MCM-22 gives higher yields of levulinic acid compared to other reported catalysts. Specifically, Cr/MCM-22 produced 73.2% levulinic acid yield from glucose at relatively high concentrations (solvent:biomass 20:1). For starting materials with higher structural complexity, pretreatment was required to maintain a high yield of levulinic acid. The novel catalyst was studied and compared to other related catalysts. The high efficiency is attributed to the synergistic effect induced by confinement control of the microporous material as well as Lewis and Brønsted acid sites of Cr/MCM-22. A reaction mechanism including all reaction steps has been proposed. The Cr/MCM-22 was successfully recycled three times.