A Study of CeSnO x and Pd/CeSnO x as Low-Temperature NO x Adsorbers with Excellent Hydrothermal Stability.

In the present work, we report on two passive NO x adsorber (PNA) material candidates: the novel support CeSnO x with and without Pd loading. The NO x adsorption and storage capacities of fresh and hydrothermally aged CeSnO x and Pd/CeSnO x were investigated. The results show that CeSnO x exhibits a rather large NO x uptake and storage capacity (28.9 μmol/g), while the loading of Pd on CeSnO x can further increase the storage capacity to 37.6 μmol/g and affect the desorption temperature of NO x . It was found that the NO x desorption temperature of Pd/CeSnO x was compatible with the efficient operating window of selective catalytic reduction (SCR) catalysts. After a hydrothermal aging treatment at 800 °C for 12 h, the NO x adsorption and storage capacities of CeSnO x and Pd/CeSnO x increased, indicating excellent hydrothermal stability. The interaction of Pd with CeSnO x , the state of Pd species, and the structure of CeSnO x and Pd/CeSnO x are studied by combination of the characterization results.