Cu-Co nanoparticles supported on nitrogen-doped carbon: An efficient catalyst for hydrogenation of 5-hydroxymethylfurfural into 2,5-bis (hydroxymethyl)furan

Production of the 2,5-Bis(hydroxymethyl)furan (BHMF) has important scientific value and strategic significance for the development of new biodegradable polyester materials. Herein, Cu-Co/N-C composites containing bimetallic nanoparticles in nitrogen-doped carbon were produced by the calcination of zeolitic imidazolate frameworks (ZIFs). They featured a cubic Cu-Co core and a porous structure derived from the ZIFs. The surface morphology, surface area, and composition of the catalysts were analyzed by scanning electron microscopy (SEM), transmission electron microscope (TEM), thermogravimetric (TG) analysis, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), CO2-temperature program desorption (CO2-TPD), and N2 adsorptiondesorption isotherms. A conversion of 93.7% of 5-hydroxymethylfurfural (HMF) with a BHMF selectivity of 92.4% was achieved using the Cu0.04Co1/N-C-450 catalyst at a relatively low reaction temperature and H2 pressure. This outstanding catalytic performance was ascribed to the high dispersion of Co nanoparticles in the N-C framework, forming Co-Nx species. We found that the synergistic catalysis of Cu-Co sites due to electron transfer contributed to the increase in the BHMF selectivity during HMF hydrogenation. The intensity of the XRD peaks corresponding to metallic Co decreased as the calcination temperature increases, which results in agglomeration of Co nanoparticles (NPs), and reduces the catalytic activity in HMF hydrogenation. Additionally, the conversion of HMF during hydrogenation remained stable after using Cu0.04Co1/N-C-450 for ten cycles.

Automated summary

In this study, Cu-Co/N-C composites were prepared by calcination of zeolitic imidazolate frameworks (ZIFs), and they exhibited excellent catalytic performance in the hydrogenation of HMF. The high dispersion of Co nanoparticles and the synergistic catalysis of Cu-Co sites were found to contribute to the increase in BHMF selectivity. Moreover, by controlling the calcination temperature, the aggregation of Co nanoparticles and catalytic activity could be regulated.