Universit├?┬á di Milano-Bicocca, Italy
Posters & Accepted Abstracts: J Material Sci Eng
Reduced oxide supports often exhibit a higher catalytic activity than the stoichiometric surface. Examples are production of liquid fuels from lignocellulose or CO oxidation to CO2. Despite the very different reactions, the catalysts are similar: Ru/TiO2 and Ru/ZrO2 in biomass conversion and Au/TiO2 and Au/ZrO2 in CO oxidation. The common denominator is that removing oxygen from the oxide surface, with formation of oxygen vacancies, results in enhanced catalytic activity. The reasons are clearly identified by studying, with a density functional theory approach, the profile for the reactions where a reduced surface gives lower barriers. However, while TiO2 is a reducible oxide, ZrO2 is not, at least if based on measures of bulk reducibility. We will show that several mechanism, in particular nano-structuring and formation of metal/oxide interfaces can drastically change the surface chemistry of an oxide making zirconia reducible and as active as titania in catalysis by oxides.