Highly dispersed Co and Ni nanoparticles encapsulated in N-doped carbon nanotubes as efficient catalysts for the reduction of unsaturated oxygen compounds in aqueous phase

Abstract

N-Doped carbon nanotube-encapsulated metal nanoparticles are of great interest in heterogeneous catalysis owing to their improved mass transfer ability and superior stability. Herein, a facile one-pot pyrolysis approach using melamine as the carbon and nitrogen source was developed to fabricate metal nanoparticles embedded in bamboo-like N-doped carbon nanotubes (named as Co@NCNTs-600-800 and Ni@NCNTs-600-800). The optimized Co@NCNTs-600-800 catalyst exhibited outstanding activity in furfural (FAL) selective hydrogenation to furfuryl alcohol (FOL) or cyclopentanone (CPO) in aqueous media. High yields of FOL (100%) and CPO (75.3%) were achieved at 80 °C and 140 °C, respectively. Besides, this cobalt catalyst showed very good stability and recyclability during the reaction. The synergistic effect between metallic cobalt and N-doped carbon nanotubes was systematically investigated. In addition, the as-prepared Ni@NCNTs-600-800 catalyst also exhibited remarkable activity. Under optimal conditions (100 °C and 4 MPa H₂ pressure), a maximum tetrahydrofurfuryl alcohol (THFOL) yield (99.5%) was obtained in the aqueous-phase hydrogenation of FAL. The research thus highlights new perspectives for non-noble metal-based N-doped carbon nanotube catalysts for biomass transformation.