Structure-Sensitive Catalytic Glycerol Oxidation on Late Transition Metals

Glycerol, a substantial byproduct of bio-diesel processing (about 10% w/w), has the potential to be selectively transformed to higher value chemicals and improve overall bio-diesel refining economics.¹ Various transition metals are suitable for catalyzing glycerol oxidation, but face a substantial selectivity challenge between various C₁, C₂, and C₃ products.² Further, despite recent developments in the shape-selective synthesis of metal nano particles, a detailed understanding of the impact of catalyst structure on the reaction selectivity is still limited. This suggests a substantial opportunity for selective glycerol oxidation if fundamental insights into the role of catalyst surface structure can be obtained and leveraged toward design.

In this presentation, we share density functional theory (DFT) calculations of glycerol oxidation mechanisms to yield glyceraldehyde and dihydroxyacetone on transition metal catalysts. Our results show that the preference for C-H vs. O-H bond breaking varies between (111) and (100) crystal facets, suggesting the possibility of manipulating product selectivity based on catalyst structure. Moreover, we show that a recently-developed energy scaling model is valid for molecules even as complex as glycerol, enabling prediction of structure-sensitive reaction energetics on nano particle models with improved computational efficiency.³ We finally highlight the importance of considering the presence of adsorbed oxygen species in stabilizing glycerol adsorption and promoting the kinetics of dehydrogenation, as has been noted previously in the literature but not extensively studied for glycerol oxidation, and discuss implications for the design of catalysts targeting the selective formation of C₃ products.

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3. L. T. Roling and F. Abild-Pedersen, ChemCatChem (2018), 10, 1643-1650.