Fabrication of carbon-supported Al2O3 nanoparticles via spontaneous cross-linking to enhance selective hydrogenation of furfural

Selective hydrogenation of furfural to furfuryl alcohol is a great challenge in the hydrogenation field due to thermodynamic preference for hydrogenation of CC over CO. Herein, a novel Al₂O₃/C-u hybrid catalyst, composed of N-modified dendritic carbon networks supporting Al₂O₃ nanoparticles, was successfully prepared via carbonizing the freeze-dried gel from spontaneous cross-linking of alginate, Al³⁺ and urea_. The obtained carbon-supported Al₂O₃ hybrid catalyst has a high ratio (31%) of Al species in pentahedral-coordinated state. The introduction of urea enhances the surface N content, the ratio of pyrrolic N, and specific surface area of catalyst, leading to improved adsorption capacity of CO and the accessibility of active sites. In the furfural hydrogenation reaction with isopropyl alcohol as hydrogen donor, Al₂O₃/C-u catalyst achieved a 90% conversion of furfural with 98.0% selectivity to furfuryl alcohol, outperforming that of commercial γ-Al₂O₃. Moreover, Al₂O₃/C-u demonstrates excellent catalytic stability in the recycling tests attributed to the synergistic effect of abundant weak Lewis acid sites and the anchoring effect of the carbon network on Al₂O₃ nanoparticles. This work provides an innovative and facile strategy for fabrication of carbon-supported Al₂O₃ hybrid catalysts with rich Al^V species, serving as a high selective hydrogenation catalyst through MPV reaction route.