Understanding the Role of Metal-Modified Mo(110) Bimetallic Surfaces for C–O/C═O and C–C Bond Scission in C3 Oxygenates

Bond scission of C–O/C═O, C–C, and C–H from oxygenates on Mo(110), Ni/Mo(110), and Co/Mo(110) has been investigated via density functional theory (DFT) calculations, temperature-programmed desorption (TPD), and high-resolution electron energy loss spectroscopy (HREELS). Propanal and 1-propanol are used as probe molecules for biomass-derived oxygenates due to their relatively high vapor pressures, allowing their easy introduction into UHV systems. DFT results predict that the binding energy trend of propanal and 1-propanol is Mo(110) > Co/Mo(110) > Ni/Mo(110), which suggests that binding energies are reduced by the modification of Mo(110) with Ni and Co admetals. TPD and HREELS results show that bond scission activity and selectivity can be tuned upon admetal modification of Mo(110). For both molecules, Mo(110) shows a highly selective deoxygenation pathway toward C–O/C═O bond scission to produce propene, while bimetallic surfaces instead exhibit a higher activity for C–C and C–H bond scission. Among the three surfaces, Ni modification leads to the highest selectivity for decarbonylation to produce ethylene and Co modification results in the highest selectivity for reforming to produce syngas.