Constructing Ni-Pt Bimetallic Catalysts for Catalytic Hydrogenation and Rearrangement of Furfural into Cyclopentanone...

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 (Al₂O₃) 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 Ni⁰/Pt⁰ and Ni²⁺/Pt⁴⁺ after reduction by H₂. The addition of a low amount of the Pt-Ni/Al₂O₃ catalyst resulted in an alleviation of H₂ reduction behavior detected by hydrogen temperature-programmed reduction, accompanied by low H₂ desorption ability observed by hydrogen temperature-programmed desorption. The catalytic activity of Ni-Pt/Al₂O₃ was higher than those of Ni/Al₂O₃ and Pt/Al₂O₃ catalysts. The maximum CPO yield was 66% with 93% FAL conversion under the optimized conditions (160 °C, 20 bar of H₂ pressure, and 2 h). Isotopic deuterium oxide (D₂O) labeling revealed the transfer of deuterium (D) atoms from D₂O 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.