Continuous flow production of γ-valerolactone from methyl-levulinate promoted by MOF-derived Al2O3–ZrO2/C catalysts

Abstract

This study investigates the catalytic transfer hydrogenation (CTH) of methyl levulinate (ML) into γ-valerolactone (GVL) using mixed metal oxides derived from metal–organic frameworks (MOFs) under continuous flow conditions. A series of MOF-derived Al₂O₃–ZrO₂/C catalysts with different Al/Zr molar ratios were investigated, revealing a synergistic effect that significantly enhances catalytic efficiency. Physico-chemical characterization demonstrates that the incorporation of aluminum into zirconium dioxide increases the surface area as well as the presence of catalytically active acid and basic sites, which are essential for the efficient transfer hydrogenation of ML into GVL. Al₂O₃–ZrO₂/C (1 : 1) exhibited the highest ML conversion rate (80%) and GVL yield (72%) at 200 °C within 30 minutes. The study also emphasizes the critical role of reaction parameters in maximizing GVL production. The stability and reusability of the Al₂O₃–ZrO₂/C (1 : 1) catalyst, following appropriate thermal treatment, were also assessed.