Screening NOx Storage Performance—Demonstrating a High Throughput Approach for Evaluating Emission Control Catalysts under Transient Conditions

At hte the high throughput (HT) approach is applied in the field of environmental catalysis on a routine basis. Research programs for automotive applications require validated screening protocols for conditions relevant to engine exhaust as well as experimental measures to ensure quality control using statistical design of experiment. To illustrate the HT approach for a test protocol with dynamic feed switches in a 48-fold reactor, 15 model catalysts for lean NOx traps (LNT) were prepared and screened fresh and after 800 degrees C hydrothermal aging. In the fresh state, highest NOx efficiency was found at 350-450 degrees C. A ranking of BaO > SrO > CaO was found as the most active NOx storage components when used as dopants on alumina. 800 degrees C aging results in a severe performance loss. Using XRD and BET analysis, Pt sintering is identified as most likely cause. These findings agree well with results from conventional tests reported in the literature.