Hydrogenation of Levulinic Acid into γ-Valerolactone Over Ruthenium Catalysts Supported on Metal-Organic Frameworks in Aqueous Medium

Liquid-phase hydrogenation of levulinic acid (LA) to gamma-valerolactone (GVL) was investigated over Metal-Organic Framework- and zeolite-supported ruthenium catalysts in aqueous media at low reaction temperature. Ru/MIL-101(Cr) showed the highest activities over Ru/MIL-100(Cr) and the investigated Ru/zeolite catalysts in terms of both turn over frequencies (TOFs) for LA-to-GVL transformation and GVL formation rate. The catalytic activity of Ru/MIL-100(Cr) was comparable to Ru/HY-zeolite (Si/Al aeyen 5.2). The Ru/MIL-101(Cr) provided a combination of both high acidity of MIL-101(Cr) support and high dispensability of metallic sites, which promotes LA hydrogenation to 4-hydroxypentanoic acid and subsequent esterification of 4-hydroxypentanoic acid to GVL via a simultaneous access of LA into the both sites. Under the investigated mild reaction conditions, both GVL selectivity and yield exceeding 99 % with a full conversion of LA were obtained by using Ru/MIL-101(Cr) catalyst at a reaction temperature of 70A degrees C after 5 h under H-2 pressure of 1.0 MPa. Moreover, Ru/MIL-101(Cr) can be easily reused at least for four times. Ruthenium immobilized on Metal-Organic Frameworks is efficiently used as recyclable catalyst for levulinic acid hydrogenation to biomass-based gamma-valerolactone. [GRAPHICS] .