Magnetically-separable cobalt catalyst embedded in metal nitrate-promoted hierarchically porous N-doped carbon nanospheres for hydrodeoxygenation of lignin-derived species

Hierarchical porous carbon nanosphere with magnetically-separable catalyst M@N C H 2 O 2 (M = Co, Ni) was constructed from the microporous resin polymer sphere as supports, which by in situ reduction of the impregnated non-noble metal nitrates. The magnetically-separable catalyst with hierarchical structure improved the mass transfer ability and the coated N-doped carbon layer on the surface of cobalt NPs stabilized the metal active site, exhibiting complete conversion hydrodeoxygenation of vanillin to 2-methoxy-4-methylphenol with selectivity of 99.4% under aqueous solutions. • Metal nitrate-promoted hierarchically porous carbon nanospheres were successfully synthesized. • The metal surface coated with a N-doped carbon layer improved its catalytic activity and stability. • H 2 O 2 post-treatment procedure improved hydrophilicity to disperse catalysts in aqueous solutions. • The as-prepared Co@N C H 2 O 2 exhibits excellent catalytic activity for vanillin hydrodeoxygenation. The creation of non-noble metal magnetically-separable heterogeneous catalysts for the hydrodeoxygenation of biomass to value-added products has received substantial attention. Herein, we report a facile synthesis of magnetically-separable cobalt catalyst embedded in hierarchically porous N-doped carbon nanospheres (Co@N C) by in situ non-noble metal nitrate-promoted pyrolysis reduction strategy using nitrogen/oxygen co-doped resin polymer spheres as precursors. The facile H 2 O 2 post-treatment process increased surface oxygen-containing groups and improved hydrophilicity to disperse catalysts in aqueous solutions. Moreover, owing to the non-noble metal nanoparticles coated with a graphitic nitrogen-doped carbon layer, the as-prepared Co@N C H 2 O 2 catalyst exhibits excellent catalytic activity and stability of vanillin hydrodeoxygenation in aqueous solutions. This strategy can be extended to other non-noble metal nitrates like M@N C H 2 O 2 (M = Co, Ni) within good recyclability, magnetically-separable ability, and general applicability for a broad substrate scope, further highlighting the superiority of our active catalysts.