Design of a Reaction Protocol for Decoupling Sulfur Removal and Thermal Aging Effects during Desulfation of Pt−BaO/Al₂O₃Lean NO_xTrap Catalysts

A novel reaction protocol was designed to decouple the effects of thermal deactivation from those due to incomplete sulfur removal during desulfation steps of Ba-based lean NOx trap catalysts. The protocol was applied to two samples: a Pt-BaO/Al2O3 model catalyst and an enhanced model sample doped with promoter species. The results obtained from the reaction protocol demonstrate that desulfation temperatures need to be maintained below those that lead to significant Pt sintering in order to prevent permanent deactivation. In addition, the modified reaction protocol allows us to compare the desulfation behavior of samples with varying degrees of sulfation, while other approaches have difficulty differentiating the effects of thermal aging from those of sulfation. We believe that this approach provides a convenient way both to assess the relative sensitivities of various catalysts to desulfation conditions, and to develop desulfation strategies that minimize the separate but often linked deactivation effects of sulfation and high temperatures.