Effect of ceria on the sulfation and desulfation characteristics of a model lean NO_x trap catalyst

The effect of ceria addition on the sulfation and desulfation characteristics of a model Ba-based lean NO _x trap (LNT) catalyst was studied. According to DRIFTS and NO _x storage capacity measurements, ceria is able to store sulfur during catalyst exposure to SO₂, thereby helping to limit sulfation of the main (Ba) NO _x storage phase and maintain NO _x storage capacity. Temperature programmed desulfation experiments revealed that desulfation of a model ceria-containing catalyst occurred in two stages, corresponding to sulfur elimination from the ceria phase at ~450 °C, followed by sulfur loss from the Ba phase at ~650 °C. Significantly, the ceria-containing catalyst displayed relatively lower sulfur evolution from the Ba phase than its non-ceria analog, confirming that the presence of ceria lessened the degree of sulfur accumulation on the Ba phase.