Rare earth metals as bi-functional sites in Cu-SSZ-39 catalysts for promotion of phosphorous and HCs resistance

The abatement of NO x from diesel vehicle exhaust is of great importance for improving the atmospheric environment. Cu-SSZ-39 zeolites possess the potential for application in the diesel vehicle aftertreatment system. Phosphorus (P) and hydrocarbons (HCs) present in the exhaust have negative impacts on the catalysts. To enhance the resistance of Cu-SSZ-39 catalysts to P and HCs, various rare earth metals were doped. Loading of 1 wt% Ce on the Cu-SSZ-39 catalyst improves the resistance to P and HCs simultaneously. The promotion mechanism was investigated through H 2 -temperature programmed reduction (H 2 -TPR), ultraviolet visible diffuse reflectance spectroscopy (UV–vis-DRS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS) and theoretical calculation. On the one hand, Ce species can act as sacrificial sites, preferentially binding with P. On the other hand, Ce doping induces the formation of CuO species, promoting the oxidation of C 3 H 6 and preventing the consumption of NH 3 from the reaction with C 3 H 6 . Ce acting as bi-functional sites enhances the P and HCs resistance of Cu-SSZ-39 catalysts, further brightening its practical application. When P and HCs are present, P poisons the active Cu sites, while HCs react with NH 3 to form HCN, resulting in the loss of NH 3 . The use of Ce doping can mitigate the poisoning effect of P on Cu, facilitating the formation of CuO, promoting the direct oxidation of HCs, and improving resistance to both P and HCs. • The resistance of P and HCs of Cu-SSZ-39 was promoted by rare earth metal modification. • Ce ions were proven to occupy D6R sites in Cu-SSZ-39 catalysts by in situ DRIFTS of NH 3 adsorption. • It is theoretically and experimentally proven that Ce acted as a sacrificial site for Cu. • The modification of Ce leads to the formation of CuO, which mitigates the negative effects of C 3 H 6 .