Analysis of Microstructural Changes in Lean No_x Trap Materials Isolates Parameters Responsible for Activity Deterioration

Conference · Sat Jan 01 04:00:00 EST 2005

OSTI ID:931263

Narula, Chaitanya Kumar ^[1]; Debusk, Melanie Moses ^[1]; Allard, Jr, Lawrence Frederick ^[1]; Lester, Kelvin K ^[1]

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1. ORNL

The rapid loss of performance of lean NO/dx 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 NO/dx adsorbers. As a result, the catalyst sites available for NO/dx oxidation and the adsorber sites available for NO/d2 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. Thus, we can analyze by TEM several selected areas of a catalyst sample for microstructural changes, starting from fresh samples and progressing through samples exposed to various operating conditions. Here, we present our results on the TEM study of a model lean NOx trap catalyst exposed to lean, rich, lean-rich cycling, and accelerated aging conditions, using our ex-situ reactor.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: EE USDOE - Office of Energy Efficiency and Renewable Energy (EE)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 931263
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
54 ENVIRONMENTAL SCIENCES
AGING
AIR POLLUTION ABATEMENT
CATALYSTS
DEACTIVATION
EXHAUST GASES
MICROSTRUCTURE
MONITORING
MORPHOLOGICAL CHANGES
NITROGEN OXIDES
OXIDATION