Technical Paper
Analysis of Microstructural Changes in Lean NOx Trap Materials Isolates Parameters Responsible for Activity Deterioration
2006-10-16
2006-01-3420
The rapid loss of performance of lean NOx traps is well-known and has been attributed to precious metal sintering, based on the analysis of catalysts aged on bench-top reactors, on dynamometers, and on vehicles. This precious metal sintering leads to reduction in surface area contact between the precious metals and NOx adsorbers. As a result, the catalyst sites available for NOx oxidation and the adsorber sites available for NO2 adsorption are drastically reduced. The use of bench-top reactors, dynos and vehicles to provide aged catalyst samples for analysis is tedious and time consuming. In order to rapidly screen catalysts for microstructural changes, we have designed an ex-situ reactor that allows us to expose catalyst samples on a TEM grid to operating conditions using a simulated exhaust.