BaTi_0.8Cu_0.2O₃ Catalysts for NO Oxidation and NO_x Storage: Effect of Synthesis Method

The effect of the synthesis method (sol–gel or hydrothermal) in the physicochemical properties of a BaTi_0.8Cu_0.2O₃ catalyst with perovskite structure was analyzed and the catalytic performance for the NO–NO₂ oxidation and for the NO_x storage was tested. The characterization of catalysts by BET, ICP-OES, XRD, XPS and H₂-TPR reveals that only the sol–gel process allows the incorporation of copper into the perovskite structure, and that, by using the hydrothermal method, highly dispersed CuO is deposited on the surface of the BaTiO₃. The NO_x storage cyclic (NSC) experiments, carried out using both catalysts, indicate that sol–gel catalyst shows a high NO_x storage capacity at 400 °C whilst the hydrothermal catalyst exhibits a high NO to NO₂ oxidation activity. For this reason, a double bed reactor configuration was tested for NSC experiments using the hydrothermal catalyst as the oxidation catalyst and the sol–gel catalyst as the NO_x trap.