Highly selective production of value-added γ-valerolactone from biomass-derived levulinic acid using the robust Pd nanoparticles

•Pd/SiO2 nanoparticles were successfully prepared through assitance of green solvent CO2.•Highly uniform dispersion of Pd nanoparticles with small size achieved.•Biofuel γ-valerolavctone was highly selectively produced under mild conditions.•The resulting Pd/SiO2 nanoparticles maintain stable catalytic activities.

A series of Pd nanoparticles deposited on the SiO2 support were facilely and successfully synthesized in the presence of the green solvent CO2, where the uniform distribution of Pd with small particle size was successfully achieved. The resulting Pd/SiO2 nanoparticles catalysts exhibited excellent catalytic performances in the selective hydrogenation of biomass-derived levulinic acid, showing close to perfect selectivity of biofuel γ-valerolactone with the TON of 884.7 at 97.3% conversion of levulinic acid. The catalytic performance was superior to the activities of the 5 wt% Pd/SiO2 nanoparticle catalyst prepared by the traditional impregnation method. Besides, the reaction parameters (e.g., the Pd loading, reaction time, reaction temperature, and hydrogen pressure), catalyst stability and reaction mechanism on the hydrogenation performance were studied. The resulting Pd nanoparticles catalysts behaved high stability in the hydrogenation.

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