Ru nanoparticles anchored on porous N-doped carbon nanospheres for efficient catalytic hydrogenation of Levulinic acid to γ-valerolactone under solvent-free conditions

•N-doped carbon nanospheres (HPNC) with hierarchical porous structure was prepared.•Ultrafine Ru NPs were anchored on the HPNC with high dispersion.•Levulinic acid can be hydrogenated to γ-valerolactone by Ru/HPNC catalyst.•The reaction conditions are solvent-free and environmentally friendly.•Ru/HPNC catalyst can be easily recovered and reused without loss of activity.