Development of New Concept Catalyst for Low CO ₂ Emission Diesel Engine Using NOx Adsorption at Low Temperatures

In this study, instead of investigating NOx storage reaction improvements, the NOx adsorption phenomenon was focused on and analyzed to improve NOx trapping performance at lower temperatures. As a NOx adsorbing material, "Ag" was expected to enhance NOx adsorption and reduce the sulfur regeneration temperature due to the abundance of adsorbed oxygen and moderate basicity. However, when using this material in an actual system, we had to reduce the sulfur regeneration temperature, increase NOx adsorption capacity and improve NOx desorption further. Addition of TiO₂, working as an acidic material, was found to decrease sulfur regeneration temperature. Additionally, it increased the NOx adsorption capacity through improved Ag dispersion which plays an important role in NOx adsorbing. Consequently, a greater NOx trapping performance than NSR catalyst was achieved at lower temperatures. In addition, we improved the NOx desorption property during diesel-rich combustion with a help of adding a minute amount of PGM, and improved the NOx reduction activity of Rhodium by improving the TWC. Consequently, one possibility to reduce NOx emission at lower temperatures in the future was presented.