Cu-Ce Bimetallic Oxide Catalyst Regulates the Intermolecular Hydrogen Transfer Reaction of 5-Hydroxymethylfurfural

The selective transformation of 5-hydroxymethylfurfural (HMF) into valuable compounds such as 2,5-diformylfuran (DFF) and 2,5-dihydroxymethylfuran (DHMF) without using external redox agents presents a promising approach. In this research, a new, cost-efficient copper-cerium bimetallic oxide catalyst (Cu1Ce5/gamma-Al2O3) was developed to catalyze the intermolecular hydrogen transfer reaction of HMF, facilitating the production of DFF and DHMF. Here, HMF serves dual roles: as a hydrogen donor, undergoing dehydrogenation to supply hydrogen, and as a hydrogen acceptor, undergoing hydrogenation to produce DHMF. This process enables a safe and effective utilization of hydrogen atoms. The catalyst was analyzed using various analytical techniques, including TEM, XRD, XPS, BET, H2-TPR, and FT-IR. The analyses and density-functional theory (DFT) simulations revealed that the creation of Cu-O-Ce interfacial sites enhances the activation of C-OH and C=O groups in HMF. This enhancement provides bifunctional catalytic active sites for dehydrogenation and hydrogenation in the intermolecular hydrogen transfer reaction of HMF. Under optimal reaction conditions (140 degrees C, 12 h), DFF and DHMF were produced simultaneously with a molar ratio of 1:1. The HMF conversion rate reached 37.1%, with DFF and DHMF selectivities at 46.6% and 46.1%, respectively. Moreover, recovery experiments indicated that the catalyst maintained good stability after five cycles, with the DFF/DHMF molar ratio consistently close to one. This demonstrates a safe and cost-effective method for the simultaneous production of DFF and DHMF through the intermolecular hydrogen transfer reaction of HMF, without the need for external redox agents.