Platinum nanoparticles supported on N-doped carbon nanotubes for the selective oxidation of glycerol to glyceric acid in a base-free aqueous solution

Abstract

Selective oxidation of glycerol was carried out over Pt catalysts supported on nitrogen-doped carbon nanotubes (Pt/N-CNTs) with molecular oxygen under atmospheric pressure in base-free aqueous solution. The N-CNTs were readily synthesized through a catalyst-free approach of annealing the mixture of CNTs and melamine. Results of X-ray diffraction, nitrogen absorption, and Raman spectroscopy confirmed that the tubular structure of CNTs was intact during annealing. Analyses of transmission electron microscopy, X-ray photon spectroscopy, and temperature-programmed desorption indicated that the surface of the CNTs was successfully functionalized with nitrogen atoms, which changed the electronic structure and surface basicity of the N-CNTs. Pt/N-CNTs out-performed Pt/CNTs for glycerol oxidation in terms of glycerol conversion and glyceric acid selectivity. Pt/N-CNTs showed highly stable catalytic performance during consecutive recycles when the used catalyst was reduced in a H₂ atmosphere.