Constructing Ni-Pt Bimetallic Catalysts for Catalytic Hydrogenation and Rearrangement of Furfural into Cyclopentanone with Insight in H/D Exchange by D 2 O Labeling.

Developing a metallic catalyst for converting furfural (FAL) to highly valuable products such as cyclopentanone (CPO) is important for fine chemical synthesis by the efficient utilization of biomass resources. The presence of diverse unsaturated carbon atoms in FAL and the rearrangement of oxygen atoms hinder the production of CPO. We developed an optimal nickel (Ni)-to-platinum (Pt) molar ratio (1:0.007) for a bimetallic Ni-Pt/alumina (Al 2 O 3 ) catalyst with a low Pt loading via an impregnation method to efficiently catalyze the selective hydrogenation of FAL in an aqueous solution to form CPO. The comprehensive characterizations by X-ray diffraction and X-ray absorption near edge structure analyses elucidated the formation of Ni 0 /Pt 0 and Ni 2+ /Pt 4+ after reduction by H 2 . The addition of a low amount of the Pt-Ni/Al 2 O 3 catalyst resulted in an alleviation of H 2 reduction behavior detected by hydrogen temperature-programmed reduction, accompanied by low H 2 desorption ability observed by hydrogen temperature-programmed desorption. The catalytic activity of Ni-Pt/Al 2 O 3 was higher than those of Ni/Al 2 O 3 and Pt/Al 2 O 3 catalysts. The maximum CPO yield was 66% with 93% FAL conversion under the optimized conditions (160 °C, 20 bar of H 2 pressure, and 2 h). Isotopic deuterium oxide (D 2 O) labeling revealed the transfer of deuterium (D) atoms from D 2 O to the intermediates and products during hydrogenation and rearrangement, which confirmed that water was a medium for rearrangement and the source of hydrogen for the reaction. This study developed an efficient catalyst for the catalytic hydrogenation and ring rearrangement of FAL into CPO.