A set of Cu/Ce/TiO2-SiO2 and K/Cu/Ce/TiO2-SiO2 catalysts was used for the simultaneous use of CO and naphthalene as reducing agents for the reduction of NO in the presence of oxygen. Only 5% of TiO2 greatly increase the activity of the catalysts. It was also found that the addition of potassium is able to tune down these oxidation reactions allowing the reduction of NO. The Cu/Ce/TiO2-SiO2 catalyst achieves the full conversion of naphthalene at 302 degrees C, 96% of CO conversion at the same temperature, and negligible conversion of NO. On the other hand, the K/Cu/Ce/TiO2-SiO2 catalyst reaches the full conversion of CO at 330 degrees C, 90% conversion of NO at 342 degrees C, and 70% conversion of naphthalene at the latter temperature.