Enhanced High-Temperature Performance of NH ₃ -SCR Catalysts for Lean-Burn Engines

NOx after-treatment has greatly limited the development of lean-burn technology for gasoline engines. NH₃-Selective Catalytic Reduction (SCR) technology has been successfully applied to NOx conversion in diesel engines. For gasoline engines, SCR catalyst is required to maintain high activity over a higher temperature window. In this study, we utilized a turbocharged and intercooled 2.0 L petrol engine to investigate the NOx conversion of two zeolite-based SCR catalysts, Cu-SSZ-13 and Fe/Cu-SSZ-13, at exhaust flows ranging from 80 to 300 kg/h and exhaust temperatures between 550 to 600°C. The catalysts were characterized using SEM, ICP, XRD, H₂-TPR, NH₃-TPD, and other methods. The selected Fe/Cu-SSZ-13 catalyst showed higher NOx conversion (>80%) in the temperature range of 550~600^oC and 80~300 kg/h exhaust gas flow. NOx output could be controlled below 10ppm. The characterization results showed that although the specific surface area and acidic sites decreased after the aging treatment for Fe/Cu-SSZ-13, they still retained active sites, showing higher activity and stability.