Thermal Aging Behavior of Pt-only TWC Converters Under Simulated Exhaust Conditions: Effect of Rare Earths (CeO2, La2O3) and Alkali (Na) Modifiers
In the present work, the feasibility to design monometallic (Pt-only), low metal loading (0.1 wt% Pt) three-way catalytic converters (TWCs), with comparable catalytic efficiency and thermostability to that of commercial bimetallic Pt/Rh TWCs has been explored. It is shown that this can be accomplish...
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Published in | Topics in catalysis Vol. 54; no. 16-18; pp. 1124 - 1134 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
Boston
Springer US
01.11.2011
|
Subjects | |
Online Access | Get full text |
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Summary: | In the present work, the feasibility to design monometallic (Pt-only), low metal loading (0.1 wt% Pt) three-way catalytic converters (TWCs), with comparable catalytic efficiency and thermostability to that of commercial bimetallic Pt/Rh TWCs has been explored. It is shown that this can be accomplished by modifying Pt/γ-Αl
2
O
3
washcoat of TWC via two different methods of promotion: support-mediated promotion by modifying the γ-Al
2
O
3
support with rare earth structure-modifiers (CeO
2
–La
2
O
3
) and surface-induced promotion by directly modifying the Pt surface with alkalies (e.g., Na), producing a doubly-promoted Pt(Na)/Al
2
O
3
-(CeO
2
–La
2
O
3
) TWC. The catalytic performance of as prepared TWCs in comparison to that of a commercial bimetallic (Pt–Rh) TWC, under simulated exhaust conditions at the stoichiometric point appears to be superior, even after severe thermal treatment at 900 °C for 5 h in air and despite the fact that the latter contain 4.5-fold higher noble metals loading. Moreover, the evolution of structural, textural and surface behavior of aged catalysts was identified by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy and diffuse reflectance infrared Fourier transform spectroscopy and appropriately correlated with the catalytic performance and thermostability of TWCs. |
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ISSN: | 1022-5528 1572-9028 |
DOI: | 10.1007/s11244-011-9734-6 |