Rational Design of Cu-SSZ-13 Catalyst for the Selective Catalytic Reduction of NOx to Meet BS-VI Emission Standards

To achieve healthier and sustainable air quality and to protect human life, worldwide emission standards are being tightened for harmful vehicular air pollutants such as CO, hydrocarbon, NOx and particulate matters. Among selective catalytic reduction catalysts for NOx control in automotive after treatment system, Cu-SSZ-13 (Chabazite structure) is one of the most promising SCR catalyst, mainly used in light and heavy duty diesel vehicles. This article focuses on the development of Cu-SSZ-13 with desired properties such crystallinity, morphology, surface area and Cu loading in the catalyst. With the help of sophisticated catalyst characterization tools such as NH₃-Temperature Programmed Desorption (TPD), Temperature Programmed Reduction (TPR), BET surface area, X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM), novel and highly active formulations of Cu-SSZ-13 are reported here. Furthermore a correlation between the physico-chemical properties and catalytic performance of the Cu-SSZ-13 catalyst has been established, allowing us to identify the most suitable properties that influences the performance and durability of the catalyst. The resulting structure-activity relationship provides a basis for the design of an improved catalyst to enhance low temperature performance and to control the undesirable reactions of forming N₂O. Monolithic wash coated Cu-SSZ-13 catalysts were tested as a function of temperature and NOx conversions were recorded. The databank generated over a wide range of operating parameters allows the design of customer specific solutions with demonstrated performance and durability.