The role of the oxide component in hybrid ceria-manganese oxide–Cu-SSZ-13 catalysts in low-temperature selective catalytic reduction of NOx by ammonia via transient experiments
Tahrizi Andana, Pacific Northwest National Laboratory
A hybrid catalytic system comprised of ceria-manganese oxide (Ce-to-Mn molar ratio = 7:3) and Cu-SSZ-13 components represents an alternative solution for improving low-temperature selective catalytic reduction (SCR) of NOx by ammonia. In the proposed system, NO oxidation over the oxide component is followed by a fast-SCR-like reaction over the zeolite component through hypothesized “bifunctional mechanism”. However, questions remain as to the true role of the metal oxide component at facilitating the improved SCR performance, which is compounded by an apparent direct relation between degree of contact between the metal oxide and zeolite component and performance.
In the present study, we studied the system under a combination of steady state and dynamic/transient conditions in an attempt to elucidate the role of the metal oxide phase at facilitating an apparent fast SCR-like reaction pathway on the zeolite phase. A conventional fast SCR pathway is not likely as the catalyst is not susceptible to typical NH4NO3 inhibition observed for Cu-SSZ-13. This talk will summarize learnings on this system and the likely role that ceria-manganese plays at enabling low-temperature SCR performance.