Selective aqueous-phase hydrogenation of D-fructose into D-mannitol using a highly efficient and reusable Cu-Ni/SiO2 catalyst.

• High Cu-Ni interaction was achieved through coprecipitation-deposition over SiO 2 at constant pH. • CuNi/SiO 2 has better catalytic performance than the corresponding monometallic catalysts. • Synergy between Cu and Ni improves catalytic performance in aqueous-phase fructose hydrogenation. • Original catalytic activity of CuNi/SiO 2 can be recovered by treatment under H 2 flow at 773 K. D-fructose hydrogenation in aqueous phase, at 373 K and 40 bar, was performed using monometallic and bimetallic Cu-Ni/SiO 2 catalysts prepared by precipitation-deposition at controlled pH, without any type of co-catalysts and/or additives in solution. The precursors and catalysts were characterized by X-ray diffraction (XRD), N 2 physisorption at 77 K, temperature programmed reduction (TPR), scanning transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDS) analysis, temperature programmed desorption of H 2 (H 2 -TPD) and X-ray photoelectron spectroscopy (XPS). The characterization of the mono and bimetallic samples showed that metal phase is composed of nanoparticles highly dispersed on SiO 2 surface. It was also found evidence that a Cu-Ni like-alloy forms in the bimetallic sample. Precisely, the best catalytic performance was obtained with the bimetallic catalyst. This was attributed to a synergistic effect between Cu and Ni, favored by the intimate contact between both elements, which was reached from the Cu-Ni coprecipitation at controlled pH over SiO 2. In a three cycles experiment performed with CuNi/SiO 2 , partial catalyst deactivation was observed. The original activity could be recovered by ex-situ reduction under H 2 flow. By temperature programmed oxidation (TPO), it was found that this deactivation is due to surface carbon species strongly chemisorbed on the metallic phase. [ABSTRACT FROM AUTHOR]