Molecular Oxygen-Promoted Synthesis of Methyl Levulinate from 5‑Hydroxymethylfurfural

Methyl levulinate (ML) is a biobased platform molecule, which has versatile applications in fine chemical synthesis and food additives. However, during the ML production, one of the main barriers is that humins are usually cogenerated, which leads to poor reaction efficiency and catalyst deactivation. The following findings are herein reported for the first time: in a catalytic system with H-beta25, molecular oxygen could act as both a humins cleaner and a reaction accelerator for the synthesis of value-added ML from 5-hydroxymethylfurfural (HMF) or furfuryl alcohol (FA). The reaction efficiency and the catalyst reusability were significantly improved in the presence of oxygen. Besides, the effects of different reaction parameters as well as catalysts have been investigated. The mechanism of ML formation from HMF in the presence of O₂ and the role of O₂ in humins removal were also proposed.