Highly dispersed Ru clusters embedded nitrogen-doped hollow carbon spheres with tunable electronic property for efficient catalytic reductive amination of biomass-derived furfural

Abstract

The catalytic reductive amination of biomass-derived carbonyl compounds into value-added primary amines has attracted significant attention in renewable biomass upgrading. Herein, highly dispersed Ru clusters embedded nitrogen-doped hollow carbon spheres (Ru@NHCS) catalysts were constructed, which achieved a 100% furfurylamine (FUA) yield, and exhibited the superior initial reaction rate of 3745.7 mmol gRu-1 h-1 and turnover frequency of 378.58 h-1 in the reductive amination of biomass-derived furfural. Systematic structure characterization indicated that the presence of abundant N species promoted the uniform dispersion of Ru clusters and induced the electronic metal-support interaction (EMSI) between Ru and NHCS support, thus leading to the formation of bifunctional Ru0 and Ruδ+ active sites. Structure-activity relationship study demonstrated that the synergistic catalysis of Ru0 and Ruδ+ active sites effectively promoted the adsorption and activation of H2 and NH3 molecules, and accelerated the hydrogenation of imine and the aminolysis of Schiff base intermediates, thereby achieving the highly selective synthesis of FUA under mild reaction conditions. Moreover, the Ru@NHCS catalyst exhibited excellent catalytic stability in the five consecutive cycles, and showed broad substrate applicability for sustainable primary amine synthesis. This work not only unveils rational design strategies for developing efficient, stable metal catalysts to achieve highly selective synthesis of value-added primary amines but also provides essential theoretical guidance for efficient biomass conversion.