Journal of Catalysis, Vol.335, 95-104, 2016
Promoting role of bismuth and antimony on Pt catalysts for the selective oxidation of glycerol to dihydroxyacetone
The group 15 metals, bismuth and antimony, play important roles in promoting noble-metal-catalyzed oxidation reactions toward high value-added chemicals. Herein, we report that the selective oxidation of glycerol to 1,3-dihydroxyacetone (DHA) catalyzed by Pt supported on N-doped carbon nanotubes (Pt/NCNT) can be significantly promoted in the presence of Bi or Sb in reaction solution. This catalyst system showed not only comparable even better performance to the Pt/NCNT with pre-loaded Bi, but also the greatly simplified catalyst preparation. It was found that the Bi-promoted Pt/NCNT underwent dynamic surface reconstruction through leaching and adsorption of Bi adatoms, due to the formation of glyceric acid. By characterizing the adsorption of Bi on Pt catalyst with high-resolution transmission electron microscopy, CO-stripping, horizontal attenuated total reflection infrared spectroscopy and X-ray photoelectron spectroscopy, it has been ascertained that Bi preferentially deposits on the step sites of Pt, and then blocks the terrace sites to promote the Pt catalyst mainly through a geometrical effect, which facilitates the activation and transformation of the secondary hydroxyl group of glycerol through the chelation between substrate and Pt-Bi sites. (C) 2016 Elsevier Inc. All rights reserved.