Polymer supported Ru nanoparticles for highly selective hydrogenation of biomass-derived levulinic acid to γ-valerolactone: Does the polymer affect the catalytic performance?

Hyperbranched polymer-supported ruthenium NPs were used for hydrogenation of levulinic acid (LA) to gamma-valerolactone (GVL) in water. The catalytic nanocomposite showed 99.9% LA conversion and 100% GVL selectivity under mild conditions and low Ru loading in batch reactor under H-2. Ru NPs formed in situ during the hydrogenation of LA demonstrated the higher catalytic activity over pre-synthesized Ru NPs. Superior catalytic properties of Ru nanocomposites are attributed both to the formation of small Ru NPs and to the effect of pyridine containing polymer support, which provides a reliable dispersion of Ru species over support and at the same time due to weak alkalinity, promotes interaction with LA thereby facilitating catalytic reaction. The functional hyperbranched polymer contributes to high stability of supported Ru NPs which was demonstrated in six consecutive catalytic cycles. TEM, XPS, EDS, XRD were used to analyze the structure, NPs distribution, and oxidation state of Ru catalysts before and after catalytic reactions.