Pd model catalysts: Effect of aging environment and lean redispersion

•Different aging environments at 700°C lead to different catalyst structures.•The aging environment severity ranking was: redox>rich-only>>lean-only.•Aged catalysts exhibited metal oxidation effects and support/additive interactions.•Exposure of aged catalysts to 700°C air improved activity despite low Pd dispersion.•Multiple 700°C air treatments were needed to restore Pd dispersion on CZO.