Tuning dual active sites of Cu/CoCeOx catalysts for efficient catalytic transfer hydrogenation of 5-hydroxymethylfurfural to biofuel 2,5-dimethylfuran

Abstract

Much attention has been attracted on the production of renewable biofuels through efficient catalytic transfer hydrogenation (CTH) reaction. In this study, a series of Cu/CoCeOx catalysts were synthesized by a facile coprecipitation method for CTH of 5-hydroxymethylfurfural (HMF) to different products with 2-propanol as a hydrogen donor, and the dual active sites of CuCo and CoCeOx were tuned via H2-reduction temperature. A 92.2% yield of 2,5-dihydroxymethylfuran (DHMF) was achieved at 150 °C over the Cu4Co8Ce4-300 catalyst, and a 95.4% yield of 2,5-dimethylfuran (DMF) was obtained over the Cu4Co10Ce2-600 catalyst at 170 °C. The roles of the dual active sites were further investigated, and the results showed that Cu species were identified as the major active sites of 2-propanol dehydrogenation, CoCeOx sites were responsible for the conversion of HMF to DHMF, and CuCo bimetallic nanoparticles promoted the cleavage of C-O in DHMF to obtain DMF. XRD, Raman, and HAADF-STEM analysis confirmed the existence of these sites. XPS and H2-TPR verified the formation of CuCo bimetallic nanoparticles, and NH3-TPD was employed to evaluate the acidity of the surface. Furthermore, in situ DRIFT of furfuryl alcohol and performance test experiments were conducted to understand the synergistic mechanism of dual active sites in hydrogen transfer from 2-propanol to HMF. This work provides a strategy to obtain different target products via tuning dual active sites.