Selective hydrogenation of levulinic acid at room temperature: Boosting ruthenium nanoparticle efficiency via coupling with in-situ pyridinic-N-doped carbon nanoflowers

Abstract

Integrating unique morphology and tunable electronic state of supported metallic catalysts via one-step is an attractive pathway to boost their catalytic behaviors in selective hydrogenation reactions. Here, electronic state-tunable Ru nanoparticles (NPs) coupled with three-dimensional (3D) hierarchical carbon nanoflowers with in-situ generated pyridinic-nitrogen (Ru/PNC) are devised. Combining with systematical characterizations, kinetics investigations, and density functional theory (DFT) computations, the pyridinic-N species is proved to facilitate the formation of electron-rich Ru, which insures the weaker adsorption of levulinic acid but stronger adsorption of H2 molecules on Ru, ultimately reducing the apparent activation energy of selective hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL). As a result, a high turnover frequency (TOF) of 5042.5 h−1 and a GVL selectivity of > 99% are achieved on the most electron-rich Ru/PNC catalyst. A positive linearity between the TOFs and the surface pyridinic-N/Ru0 ratios is recognized, further corroborating the electron-rich Ru-mediated intrinsic activity enhancement evoked by the surface pyridinic-N species on carbon nanoflowers.