Characterization of Vehicle and Laboratory Aged Commercial Three Way Catalyst: A Morphological and Functional Correlation between Real and Simulated Ageing.

The increasingly stringent emission limits require high performances also at high mileage, increasing the need for reliable catalysts characterization during their whole useful life. Thermal ageing is the main problem: high temperatures, variable environment and the presence of water lead to a progressive deactivation of the components. Due to the cost of ageing a converter on-road or on an engine bench, much more rapid laboratory aging methods are now becoming very interesting, rising the problem of the correlation between real and accelerated ageing conditions. In this work a series of identical catalysts aged in different conditions are characterized in order to understand the correlation between the real and accelerated ageing protocols. Applying a wide spectrum of techniques (XRD, SEM, TEM, BET) a complete morphological characterization is performed and interlaced with functional testing, in order to understand the link between the catalysts modification due to thermal effects and their deactivation, and to allow the design of more realistic laboratory ageing protocols. The correlation between real samples, coming from an ageing on an engine, and laboratory ageing is good for the medium-high mileage sample, which results very similar in terms of performance and morphology with the sample aged at hydro-thermal condition. Some differences remain due to the chemical ageing, which was not possible to replicate on the laboratory scale. [ABSTRACT FROM AUTHOR]