Abstract
Bimetallic AuPt nanoparticles with different Au:Pt ratios (molar ratio: 9-1, 8-2, 6-4, 2-8, 1-9) and the corresponding Au and Pt monometallic ones were prepared by sol immobilization and immobilized on commercial TiO2 (P25). The catalytic activity was evaluated in the liquid phase glycerol oxidation in presence and absence of a base (NaOH). It was found that the Au:Pt molar ratio and reaction conditions strongly influence the catalytic performance. In the presence of NaOH, Au-rich catalysts were more active than Pt-rich ones, with the highest activity observed for Au9Pt1/TiO2 (6575 h−1). In absence of a base, a higher content of Pt is needed to produce the most active catalyst (Au6Pt4/TiO2, 301 h−1). In terms of selectivity, in presence of NaOH, Au-rich catalysts showed a high selectivity to C3 products (63–72%) whereas Pt-rich catalysts promote the formation of formic and glycolic acids. The opposite trend was observed in absence of a base with Pt-rich catalysts showing higher selectivity to C3 products (83–88%).
Highlights
Biomass is a valid renewable alternative to fossil fuels for the production of valuable fine chemicals and fuels [1,2]
Au and Pt monometallic ones were prepared by the sol immobilization method using polyvinyl alcohol (PVA) as protective agent, following an experimental procedure reported by our group [26,27]
The morphology of the catalysts was investigated by means of transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS)
Summary
Biomass is a valid renewable alternative to fossil fuels for the production of valuable fine chemicals and fuels [1,2]. We have shown that at 80 ◦ C, basic supports (MgO, NiO) promoted the activity and increased C-C bond cleavage reactions, whereas acidic supports (MCM41, SiO2 , H-mordenite and sulfated-ZrO2 ) showed a higher selectivity (>80%) to C3 oxidation products, glyceric acid and glyceraldehyde) [21]. Yang et al reported a selectivity of 60.4% to glyceric acid and 25.7% to glyceraldehyde at 60.4% of conversion using Pt70 Au10 /graphene-oxide [23] Most of these systems seem to suffer from deactivation after prolonged reuses, probably due to leaching into the solution of the active phase or irreversible adsorption of the diacid products.
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