Universal activity function for predicting performance of Pd-based TWC as function of Pd loading and catalyst mileage

Kinetic model for modern double-layered Pd/Rh TWC as a function of metal loadings and mileage

“…The laboratory aging program employed in this study is a laboratory version of the rapid aging test (RAT) protocol developed originally by GM R&D for the engine-dynamometer testing of TWCs containing Pt, Pd and Rh [14]. The laboratory aging program employed in the present study was well correlated with the engine-dynamometer aged (4 k and 100 k miles) and the field aged mileages (41 k and 98 k miles) of the commercial Pd-based TWCs [8] as clearly demonstrated in Figs. S2 and S3 of the Supplementary data, even though the catalyst mileage of the Rh-based TWCs obtained from the laboratory aging program has not been directly compared with its actual in-service mileage due to the absence of the field-aged commercial Rh catalyst samples.…”

“…S2 and S3 of the Supplementary data, even though the catalyst mileage of the Rh-based TWCs obtained from the laboratory aging program has not been directly compared with its actual in-service mileage due to the absence of the field-aged commercial Rh catalyst samples. Note that the 4 k mile-stabilized TWC was employed as the fresh catalyst in this study, and its condition was used as the initial condition in the numerical simulation of the deactivation kinetic model [3,8]. The metal surface area (MSA) and dispersion of Rh over the Rh-based TWCs were determined by a pulse CO chemisorption method (Autochem II 2920, Micromeritics Co.) [3].…”

“…In addition, the 3D activity function for the Pd-based TWC (a Pd ) was derived from the alteration of the Pd MSA with respect to both the Pd loading and the catalyst mileage, which can be used in the numerical simulation of the catalytic performance of commercial Pd-based TWCs [8]. As shown in Fig.…”

“…To quantify the effect of the PGM loading and catalyst mileage on the performance variation of automotive catalytic systems, the concept of activity function has been introduced on the basis of the variation of the active metal surface area (MSA) of the Pdbased TWC [3,8,9]. A similar approach has been applied to the Pt-based diesel oxidation catalyst (DOC) through the use of a scaling factor to adjust the frequency factor of the reaction rate constant [5,10].…”

A new insight into the effects of barium addition on Pd-only catalysts: Pd-support interface and CO+NO reaction pathway

“…Details of the procedure for CO chemisorption were described elsewhere [18]. The dispersion and particle size of palladium were calculated by the following equations [24,25]:…”