Hydrophobic Pd nanocatalysts for one-pot and high-yield production of liquid furanic biofuels at low temperatures

Liquid furanic hydrocarbons, a class of biomass-based fuels and chemicals, are typically required to achieve moderate product selectivity and yield under harsh conditions (e.g., high temperature and H2 pressure) involving multi-step processes over different catalysts. In this study, a single-step catalytic process was developed for direct conversion of various saccharides to furanic biofuels such as 2,5-dimethylfuran and 2-methylfuran with high yields (>95%) at 110-130 degrees C. The negatively charged hydride (H-) of readily available polymethylhydrosiloxane (PMHS) acting as green H-donor over hydrophobic Pd nanoparticles did not obstruct upstream reactions (e.g., hydrolysis, isomerization and dehydration) for the in situ formation of furanic aldehydes/alcohols from sugars, and could selectively facilitate the subsequent hydrodeoxygenation of carbonyl and hydroxyl groups other than the furanic ring in one pot, as clarified by deuterium-labeling study. Importantly, the unreduced Pd(II) nanocatalysts also exhibited comparable performance in the selective hydrodeoxygenation reaction. Moreover, the catalytic strategy was extended to various carboxides for quantitative production of corresponding furanic/aromatic hydrocarbons at room temperature that were more pronounced than previously reported results, and the optimal PcIIMIL-53(A1) coated with polydimethylsiloxane (Pd/MIL-53(Al)-P) was highly stable with little deactivation and Pd leaching for at least five consecutive cycles. (C) 2017 Elsevier B.V. All rights reserved.