Ru nanoparticles deposited on ultrathin TiO2 nanosheets as highly active catalyst for levulinic acid hydrogenation to γ-valerolactone

Highly efficient synthesis of valuable y-valerolactone (GVL) by levulinic acid (LA) hydrogenation is still a challenge for Ru-based catalysts under mild condition. In this work, we have reported that ultrathin TiO2 nanosheets supported Ru nanoparticles showed extraordinarily high catalytic activity, GVL yield (99.1%) and reusability owing to the formation of Ru-O-Ti interfacial structure. The turnover frequency (TOF) reached as high as 19,045 h(-1) at 100 degrees C, much higher than those of Ru/SiO2, Ru/GO, Ru/MoS2, and commercial Ru/C. DFT calculation elucidates that the dominant reaction pathway of LA hydrogenation to GVL is preferentially hydrogenated to CH3CHOCH2CH2COOH*, followed by cyclization to CH3(OH)C4OH4OH* (GVL - OH) and final dehydroxylation, irrespective of surface structure. Compared to Ru (0 0 2) facet, Ru/TiO2 interfacial structure changes the rate-determining step from initial hydrogenation to cyclization, which greatly declines the activation barrier from 0.81 eV to 0.48 eV.