Aging effects on commercial lean NOx trap catalysts
In this work, commercial LNT catalysts were aged and characterized in order to elucidate the effect of aging on their performance and to establish a correlation with an accelerated aging method. A vehicle-aged catalyst was driven in the vehicle chassis dynamometer for 100 000 km, while a rapid-aged catalyst was treated at 800 °C for a period of time equivalent to a driving distance of 160 000 km. Engine dynamometer studies were performed with the purpose of testing the NOx storage and reduction performance of the LNT samples. This testing campaign was followed by running some vehicle emission cycles in the vehicle chassis dynamometer with a 2.0 l Volvo diesel vehicle with the aim of studying the catalysts’ performance under real driving conditions and monitoring the gradual deterioration of the vehicle-aged catalyst during aging. Afterwards, detailed characterization studies were carried out on a flow reactor with small cylindrical cores extracted from commercial LNT catalysts. Physicochemical characterization techniques were also employed in this investigation.
The catalyst evaluation revealed that aging resulted in a significant deterioration of NOx storage and reduction functions as a consequence of precious metal sintering, loss of surface area of the NOx storage and support compounds, phase transitions of the adsorber material, and a large accumulation of poison species, especially at the catalyst inlet. Among the aged samples examined, the middle (lengthwise) vehicle-aged sample showed the highest catalytic activity since it was exposed to both chemical poisoning and thermal degradation to a lesser extent. It was found that the oven-aged method proposed in this study is definitely a good approach to mimic the long-term catalytic activity in which the thermal stress applied is able to replicate the NO oxidation and NOx storage activity of a 100 000 km vehicle-aged catalyst.
commercial lean NOx traps
NOx storage and reduction
Jesus De Abreu Goes
Kemisk apparat- och reaktionsteknik
Performance Studies and Correlation between Vehicle- and Rapid- Aged Commercial Lean NOx Trap Catalysts
SAE International Journal of Engines,; Vol. 10(2017)p. 1613-1626
Paper i proceeding
De Abreu Goes, J., Kristoffersson, A., Wentworth, T., and Olsson, L., Detailed Characterization Studies of Vehicle- and Rapid-Aged Commercial Lean NOx Trap Catalysts
Chalmers tekniska högskola
Lecture hall KB, Kemihuset, Kemigården 4