Oxygen Healing and CO 2 /H 2 /Anisole Dissociation on Reduced Molybdenum Oxide Surfaces Studied by Density Functional Theory

Reduced molybdenum oxides are versatile catalysts for deoxygenation and hydrodeoxygenation reactions. In this work, we have performed spin-polarized DFT calculations to investigate oxygen healing energies on reduced molybdenum oxides (reduced α-MoO , γ-Mo O and MoO ). We find that Mo on MoO (100) is the most active for abstracting an oxygen from the oxygenated compounds. We further explored CO adsorption and dissociation on reduced α-MoO (010) and MoO (100). In comparison to reduced α-MoO (010), CO adsorbs more strongly on MoO (100). We find that CO dissociates on MoO (100) via a two-step process, the overall barrier for which is 0.6 eV. This barrier is 1.7 eV lower than that on reduced α-MoO (010), suggesting a much higher activity for deoxygenation of CO to CO. As H dissociation is shown to be the rate-limiting step for hydrodeoxygenation reactions, we also studied activation barriers for H chemisorption on MoO (100). We find that the chemisorption barriers are 0.7 eV lower than that reported on reduced α-MoO (010). Finally, we have studied the dissociation (C-O cleavage) of anisole (a lignin-based biofuel model compound) on MoO (100). We find that anisole binds very strongly on MoO (100) with an adsorption energy of -1.47 eV. According to Sabatier's principle, strongly adsorbing reactants poison the catalyst surface, which may explain the low activity of MoO observed during experiments for hydrodeoxygenation of anisole.