Hydrogenation and Ring-rearrangement of Furfural to Cyclopentanone over Ultralow-loading Ni-Pt Supported on Layered AlOOH

Constructing efficient and inexpensive metal catalysts to produce cyclopentanone (CPO) from furfural (FFL) is of great significance for the utilization of biomass and synthesis of fine chemicals. The synergy of metal site and acid site is a key factor for hydrogenation of carbonyl and ring-rearrangement. Herein, AlOOH is synthesized to support base metal, nickel (1 %), and ultralow-loading platinum (0.1 %) for the complete conversion of CPO from FFL efficiently and selectively, which is difficult to achieve with common Al₂O₃ as support. Through infrared spectroscopy characterization and H₂-temperature-programmed reduction, Ni₁Pt_0.1/AlOOH has stronger adsorption of the hydroxyl group of FFL and tight bonding between metals promotes the reduction of the overall active sites. Comparison to Ni₁/AlOOH and Pt_0.1/AlOOH individually, the addition of 0.1 wt % Pt enables Ni to play the same role as Pt in hydrogenation while being cheaper. Layered AlOOH has higher activity than common Al₂O₃. The structure of layered hydroxides and the use of water as a solvent promote the hydrogenation of aldehyde group and ring-arrangement. Under the optimized conditions (150 °C, 40 bar of H₂, and 6 h), Ni₁Pt_0.1/AlOOH achieves 98 % selectivity for CPO. Isotope labeling experiments revealed that H-H bond cleavage affects both hydrogenation and rearrangement, while OH bond cleavage in water impacts only rearrangement. This study not only developed an ultralow-loading bimetal catalyst for the efficient hydrogenation and ring-rearrangement of FFL to CPO, but also explored the synergy between noble metals and base metals, as well as between metal sites and acid sites.