Transfer hydrogenation of furfural to furfuryl alcohol over modified Zr-based catalysts using primary alcohols as H-donors

Catalytic transfer hydrogenation is gaining increasing attention as a promising alternative to conventional hydrogenation with H₂. In present work, a series of modified Zr-based catalysts were synthesized and tested for furfural catalytic transfer hydrogenation into furfuryl alcohol (FA). The results indicated that more than 13 % of furfural conversion and furfuryl alcohol yield could be achieved with modified zirconium hydroxide (mZrH) at 140 °C when compared with zirconium hydroxide (ZrH) using ethanol as H-donor and solvent in continuous flow regime, and the activity could be further enhanced by increasing the reaction temperature or Ru loading on the catalyst. The best result of 92 % furfural conversion with ∼99 % FA selectivity was obtained at 150 °C with 6% Ru/mZrH as catalyst, and the productivity of FA is 5.5 mmol g⁻¹ h⁻¹ which is 2 times higher than that reported with ZrH in batch. Moreover, long-term stability study of the catalysts indicated that 6% Ru/mZrH not only performs a better activity, but also a better stability than 6% Ru/ZrH. Characterizations of the catalysts by BET, XRD, EA, IR, SEM-EDS, XPS and CO₂ adsorption indicated that zirconium hydroxide (ZrH) was successfully modified with hydroxylamine, leading to significantly change of its morphology and basic sites. And the deactivation of the catalysts was due to both the leaching of Ru and the deposition of side-products on its surface.