Copper Catalysts Supported on Barium Deficient Perovskites for CO Oxidation Reaction

Mixed oxides with perovskite-type structure (ABO(3)) present interesting physico-chemical properties to be used as catalyst for atmospheric pollution control. In this work, a series of CuX/Ba0.7MnO3 catalysts (being x: 0, 4, 8 and 12 wt%) has been synthesized, characterized and tested for CO oxidation reaction. All the catalysts were active for CO oxidation in the two reactant mixtures tested: low CO mixture (0.1% CO and 1% O-2 in He) and near stoichiometric mixture (1% CO and 1% O-2 in He). Copper-free perovskite is the most active catalyst in the less demanding conditions (0.1% CO and 1% O-2), as it presents the highest amount of oxygen vacancies working as active sites. However, at higher CO concentrations (1% CO in near stoichiometric mixture), copper-containing catalysts were more active than the perovskite support because, due to the saturation of the oxygen vacancies of perovskites, CuO seems to participate as active site for CO and O-2 activation. Cu4/Ba0.7MnO3 and Cu12/Ba0.7MnO3 are more active than Cu8/Ba0.7MnO3 catalyst, since they present a larger amount of active sites on surface. These two copper-containing catalysts present a high stability and recyclability during the reaction at 300 degrees C in an ideal near stoichiometric mixture (1% CO and 1% O-2).