Gold on titania: Effect of preparation method in the liquid phase oxidation

Abstract

The effect of preparation method (deposition-precipitation versus sol immobilisation method) and reduction method (calcination versus chemical reduction) on Au/TiO 2 catalysts for the liquid phase oxidation of glycerol has been studied. It was revealed that a different trend existed in terms of activity and distribution of products. The catalytic activity is shown to be dependent not only on the choice of the reduction method but also on the use of protective agent (PVA, THPC) for the stabilization of the gold colloids. In fact, the highest activity was found when a low temperature chemical reduction was employed on a Au/TiO 2 sample synthesised by the deposition-precipitation method. The use of a higher pre-treatment temperature or of a protective agent resulted in a lower activity but could be used to direct selectivity in oxidation reactions. The structural data (HRTEM and XPS) along with the catalytic results indicate that the combination of metallic Au 0 species with small particle size (2-5 nm) are responsible for the high activity observed in the liquid phase oxidation of glycerol. #

Effect of Selected Factors on Catalytic Activity of Bimetallic Copper-Gold Catalysts in Selective Oxidation of Glycerol

“…Gold loaded on ceria, zirconia and cerium-zirconium mixed oxide was characterised in the XP two doublets attributed to different gold species (Figures S5 and S6), corresponding to (Au 0 ) gold particles loading on the surface of catalysts [33,66]. The smaller size of metallic gold particles in 518 the bimetallic catalysts was confirmed by the STEM-EDXS results (Fig.…”

“…glycolic acid and/or formic acid, but the selectivities to these reagents were much lower 111 than the selectivity to glyceric acid. These products were obtained in the earlier studies [33][34][35][36][37].…”

Effects of Support and Synthetic Procedure for Sol-Immobilized Au Nanoparticles

“…In particular, it is possible to observe that for the samples supported on TiO 2 the quantity of sulphate ions is remarkable. This is reasonable, since for this support in order to load an adequate gold amount it is necessary to acidify the support before metal introduction [23]. As previously reported, in the sol immobilization method the surfactant has the fundamental role of maintaining gold nanoparticles separated, in order to avoid their sintering and deactivation.…”

Biomass-derived Platform Molecules Upgrading through Catalytic Processes: Yielding Chemicals and Fuels

“…However, a consensus is clearly established on some general behavior, i.e., on the efficiency of some metallic active phases. In early works, the supported metallic Pt 101) and the derivative catalytic systems such as Pt _ Bi 102) and Pd 103) were identified as efficient for converting glycerol. Extended works were also focused on the use of gold-based catalysts.…”