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- Title
NO Adsorption and Reaction on Aged Pd-Rh Natural Gas Vehicle Catalysts: A Combined TAP and Steady-State Kinetic Approach.
- Authors
Granger, Pascal; Renème, Y.; Dhainaut, F.; Schuurman, Y.; Mirodatos, C.
- Abstract
A combined temporal analysis of products (TAP) and steady-state kinetic study was achieved to characterize the surface reactivity of fresh and aged bimetallic Pd-Rh/AlO Natural-Gas Vehicle catalysts. Single NO pulse TAP experiments were performed on a stabilized surface after exposure to successive NO pulses until to get a steady-state NO conversion. Outlet flow curves recorded during such experiments show fast reaction steps taking place on noble metal particles and a slow process during NO desorption ascribed to the involvement of spill-over effect of chemisorbed NO molecules from the metal to the support. This slow process attenuates on the aged sample likely due to an alteration of the metal/support interface induced by particle sintering at high temperature. Thermal aging also alters the surface composition of bimetallic Pd-Rh particles which leads to changes in the products distribution from NO dissociation. A similar selectivity behavior is observed from steady-state kinetic measurements during the NO/H reaction. Interestingly, a weak partial pressure dependency of the selectivity reflects a surface Rh enrichment of Pd-Rh particles during aging.
- Subjects
NATURAL gas vehicles; NITROGEN oxide absorption &; adsorption; SURFACE chemistry; STEADY-state flow; CHEMICAL kinetics
- Publication
Topics in Catalysis, 2017, Vol 60, Issue 3-5, p289
- ISSN
1022-5528
- Publication type
Article
- DOI
10.1007/s11244-016-0613-z