Tunable selectivity of Ni catalysts in the hydrogenation reaction of 5-hydroxymethylfurfural in aqueous media: Role of the carbon supports

In addition to the nature of the solvent, the intrinsic metal properties and degree of dispersion, the selective hydrogenation of 5-hydroxymethylfurfural (HMF) has been reported to be greatly affected by the nature of the support. In this work, four Ni catalysts were prepared starting from different carbonaceous supports ─with diverse graphitic and porous structure─ and comparatively evaluated in the hydrogenation reaction of HMF. The reaction was conducted in a batch stirred reactor under 30 bar H2 pressure at 60 °C in aqueous media. Ni supported on a commercial silica and Raney Ni were also tested for reference purposes. We found that carbon supports limit in some extent the reactivity of Ni towards CC hydrogenation, offering higher selectivity to the carbonyl hydrogenated compound, 2,5-di-hydroxymethylfuran (DHMF), in detrimental to the total hydrogenated derivative, 2,5-di-hydroxymethyl-tetrahydrofuran (DHMTHF). However, the latter was the major product over Raney Ni and Ni/SiO2. The unusual catalytic performance of our Ni/carbon catalysts was related to the composition, structural and surface properties. Among all tested Ni/carbon catalysts, Ni over the commercial high surface area graphite (HSAG) exhibited the best catalytic behaviour in terms of DHMF selectivity (90%) and intrinsic catalytic activity. Furthermore, Ni/HSAG displayed satisfactory stability after three consecutive runs. [Display omitted] •Carbon supports inhibit the characteristic overhydrogenation activity of Ni.•However, Ni/SiO2 and Raney Ni promote the hydrogenation of the furan-ring.•Ni/HSAG afforded 90% selectivity towards the partial hydrogenation product at 60 °C.•At 180 °C the hydrogenative rearrangement of the furan ring is favored.