NOx Trap Aging Mechanisms
Jim Parks, EmeraChem
NOx adsorber catalysts (“NOx traps”) are aftertreatment devices that require active controls. The controls must enable efficient catalyst regeneration and NOx reduction over a broad range of operating conditions. Sulfur management (deSulfation) of the catalyst must also be controlled. A complicating factor in the development of catalyst models and control strategies is the fact that catalyst materials change over time. As the catalyst materials and performance properties change, control strategies will need to adapt to the new catalyst state to enable the efficiency of the system to be optimal. NOx traps have been aged in engine exhaust with accelerated conditioning, which included high levels of sulfur and aggressive thermal exposure. The changes in NOx trap performance during aging will be presented, and experimental analysis of catalyst materials will also be presented. The results will be discussed in the interest of generating focal points for the incorporation of catalyst aging into catalyst models and control strategies.