High-temperature reduction improves the activity of rutile TiO2 nanowires-supported gold-copper bimetallic nanoparticles for cellobiose to gluconic acid conversion

摘要

Titania nanowires (NW) supported gold-copper (Au-Cu) bimetallic nanoparticles were synthesized and pretreated in hydrogen and air at 300,500 and 700 degrees C, for the one-pot conversion of cellobiose to gluconic acid. Catalyst samples were characterized by temperature-programmed desorption of NH3, Fourier transform infrared spectroscopy (FT-IR), Energy-dispersive X-ray spectroscopy, Field emission scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRD), Transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The structure and activity of Au-Cu/TiO2 NW were highly affected by the pretreatment conditions. Catalyst samples reduced in H-2 and at higher temperatures resulted better catalytic performance as compared with those calcinated in air at the same temperature. The influence of support, calcination temperature and atmosphere as well as gold content on the catalytic performance of Au-Cu/TiO2 NWs are investigated. The characterization results suggested high hydrogen reduction temperature created oxygen vacant sites on the titania NW support. This is consequently associated with the stabilization of highly reactive oxygen species at the periphery of the metal-support interface. Interactions between the metals and the titania NWs support and between the promoter and the active metal enhanced the formation of gluconic acid. (C) 2015 Elsevier B.V. All rights reserved.