Composition/Performance Evaluation of Lean NO_xTrap Catalysts for Coupling with SCR Technology

The washcoat composition and the catalytic properties of two commercially available lean NOx traps (LNTs) were investigated. Both catalysts contained nominally same storage materials but differed strongly in their amount activity as well layered architecture. In lean-rich cycle experiments under realistic engine-out gas compositions using a laboratory test bench, LNTs showed comparable behavior. At temperatures below 250 °C, phase durations last up to 300 s until 50 % capacity is reached. simultaneously calculated efficiencies drop rapidly 35 %, resulting high slip. Strong variations observed N2O NH3 selectivity CO slip during regeneration both caused by different oxygen (OSC), water shift (WGS) rhodium distribution layers. Based on obtained results, proposals made optimize performance, leading highly efficient LNT for coupling with downstream SCR catalyst.