To gain further mechanistic insights on hydrgen production from biomass-derived glycerol using improved bimetallic catalysts, the catalytic behaviors of these bond scissions associated with glycerol decomposition on Pt-Mo alloy-based catalysts are studied using periodic Density Functional Theory (DFT) and linear scaling relationships. An important consideration is the structure of Pt-Mo bimetallic alloy under aqueous phase environment, where the Mo sites are most likely present oxidized and covered by hydroxyl groups. The surface configurations will be significantly modified as a result of MoO<sub>x</sub> formation. The surface reconstruction and segregation of MoO<sub>x</sub> from Pt at the nanoscale are investigated using DFT calculations, whereas the catalytic functionalities of oxidized Pt-Mo surfaces during glycerol decompositions are also studied. Our bond-order based scaling relationship developed for monometallic surfaces was validated and extended to this multi-component nanocatalyst system based on the binding energies of atomic C and O on several Pt-Mo alloy surface configurations. This approach can be used to accelerate our catalytic trend analysis. In this paper, we will show that the Pt-skin alloy surfaces exhibit similar glycerol decomposition trends to pure Pt surfaces, with weaker C, O binding, the thermodynamics of glycerol decomposition becomes more endothermic. The weaker CO binding may actually allow more active sites for glycerol dehydrogenation and C-C bond scission. Mo sites may favor O-H, C-O bond scissions; in aqueous phase reforming conditions, water-gas shift reactions could also be affected favorably at such sites. The study reveals a promising bifunctional mechanism exhibited by the Pt-Mo bimetallic alloy as a reforming catalyst.

Mechanistic insights on glycerol decomposition on PtMo bimetallic catalysts from first-principles methods

249th National Meeting (2015)

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