Platinum-rhodium synergism in three-way automotive catalysts

Journal Article · Fri Feb 28 23:00:00 EST 1986 · J. Catal.; (United States)

DOI:https://doi.org/10.1016/0021-9517(86)90307-6· OSTI ID:5217109

Oh, S H; Carpenter, J E

The interactions between Pt and Rh in three-way automotive catalysts were investigated by conducting laboratory reactor experiments with both a Pt/Rh bimetallic catalyst (prepared by stepwise metal impregnation) and a physical mixture of Pt and Rh monometallic catalysts while holding the absolute amount of each of the noble metals constant. Activity measurements in a CO-NO-O/sub 2/ feedstream have shown that the CO oxidation activity of the bimetallic catalyst is substantially higher than that of the physical mixture over the concentration and temperature ranges characteristic of the converter warmup period. This synergistic enhancement of CO oxidation activity in the bimetallic catalyst can be rationalized by visualizing the catalyst surface structure as a statistical mixture of Pt and Rh sites. It was found that such a desirable surface structure (and the attendant synergistic activity enhancement) cannot be obtained by simultaneous impregnation of the noble metals because this catalyst preparation procedure leads to preferential Rh enrichment on the catalyst surface under the net-oxidizing reaction conditions considered in this study.

• Research Organization: General Motors Research Labs., Warren, MI (USA)
• OSTI ID: 5217109
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 98:1; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
330701 -- Emission Control-- Nitrogen Oxides
330702 -- Emission Control-- Carbon Monoxide
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
BENCH-SCALE EXPERIMENTS
BIMETALS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYSTS
CATALYTIC CONVERTERS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTIONS
DISPERSIONS
ELEMENTS
EQUIPMENT
HYDROCARBONS
METALS
MIXTURES
NITRIC OXIDE
NITROGEN COMPOUNDS
NITROGEN OXIDES
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PLATINUM
PLATINUM METALS
POLLUTION CONTROL EQUIPMENT
REDUCTION
RHODIUM
SYNERGISM
TRANSITION ELEMENTS