Versatility of Supported Gold Nanoparticles on Hydrotalcites used for Oxidation and Reduction Reactions

Abstract

Regardless of their size, supported gold nanoparticles are largely used for liquid-phase oxidation reactions. Small gold nanoparticles exhibit good performance during the reduction of organic compounds. The direct reduction of carboxylic acid to aldehyde is a famous and familiar reaction in the field of organic chemistry and is considered as one of the fundamental chemical transformations. Herein, we present Au/hydrotalcite, Au/MgO, and Au/Al2O3 systems as heterogeneous versatile catalysts to realize the oxidation of furfural (FF) to furoic acid (FA) and realize the reduction of FA to FF. Experiments showed that in standard aqueous conditions under air, FF can be easily oxidized to FA. When DMSO was used as a solvent to conduct the experiments under an atmosphere of CO2, FA was reduced to FF. The Au/HT series of catalysts was found to be active in both transformations, pointing out the versatility of the gold-based catalysts. The activity significantly depends on the acid-base properties of the catalyst.

Tuning Au/SiO2 nanostructures from 1D to 3D interconnected nanotube networks using polycarbonate porous templates

“…Functionalization of free 1D and 3D networks of silica nanotubes with gold nanoparticles Among the various methods (e.g. direct reduction of gold salt, 33 sol-gel process 34 or the synthesis of Au NPs in colloidal suspension prior to deposition 35 ) reported for Au NP deposition on SiO 2 , electroless deposition of Au appears as a method of choice, as shown by Kobayashi et al, 36 who produced homogeneously dispersed Au NPs of a few nanometers on spherical silica. Furthermore, this in situ deposition method has the advantage of avoiding any problems related to the diffusion and/or adhesion of Au NPs (prepared ex situ) onto the supporting structures.…”