Role of rhodium in Rh/Pt catalysts for CO/HC/NOx and SO/sub 4/ = emission control: the influence of oxygen on catalyst performance
Conference
·
OSTI ID:7215835
The use of Rh/Pt catalysts in automobile exhaust emission control is now well established. These catalysts are applicable in both the conventional CO/HC control system and the more novel TWC (three way catalysts) approach seeking to control CO, HC and NO/sub x/ emissions simultaneously. During comparative investigations of Rh/Pt vs. Pt catalysts it has become apparent that Rh/Pt catalysts possess certain features which are absent in other noble metal combinations. Thus in general Rh/Pt catalysts show much greater ability to convert NO/sub x/ under TWC conditions, and produce lower sulfate emissions under net oxidizing conditions. On the other hand Rh/Pt can show lower HC conversion and durability than other noble metal combinations when operated under vast excess of oxygen. Surface studies revealed that these effects can be attributed in part to surface enrichment of the Rh/Pt system by the rhodium component. This is followed by oxidation to produce durable surface species which are inactive to sulfate formation, and reduce the activity of the catalyst to HC conversion. The role of such species in the conversion of NO/sub x/ is discussed, and possible solutions to this problem are outlined in terms of catalyst design criteria.
- OSTI ID:
- 7215835
- Report Number(s):
- CONF-770205-26
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
33 ADVANCED PROPULSION SYSTEMS
330701* -- Emission Control-- Nitrogen Oxides
330702 -- Emission Control-- Carbon Monoxide
330703 -- Emission Control-- Sulfur Dioxide
330704 -- Emission Control-- Hydrocarbons
AIR POLLUTION CONTROL
AUTOMOBILES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYSTS
CATALYTIC CONVERTERS
CHALCOGENIDES
ELEMENTS
EQUIPMENT
EXHAUST GASES
GASEOUS WASTES
HYDROCARBONS
METALS
NITROGEN COMPOUNDS
NITROGEN OXIDES
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM
PLATINUM METALS
POLLUTION CONTROL
POLLUTION CONTROL EQUIPMENT
REFRACTORY METALS
RHODIUM
SULFATES
SULFUR COMPOUNDS
SURFACE PROPERTIES
TRANSITION ELEMENTS
VEHICLES
WASTES
330701* -- Emission Control-- Nitrogen Oxides
330702 -- Emission Control-- Carbon Monoxide
330703 -- Emission Control-- Sulfur Dioxide
330704 -- Emission Control-- Hydrocarbons
AIR POLLUTION CONTROL
AUTOMOBILES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYSTS
CATALYTIC CONVERTERS
CHALCOGENIDES
ELEMENTS
EQUIPMENT
EXHAUST GASES
GASEOUS WASTES
HYDROCARBONS
METALS
NITROGEN COMPOUNDS
NITROGEN OXIDES
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM
PLATINUM METALS
POLLUTION CONTROL
POLLUTION CONTROL EQUIPMENT
REFRACTORY METALS
RHODIUM
SULFATES
SULFUR COMPOUNDS
SURFACE PROPERTIES
TRANSITION ELEMENTS
VEHICLES
WASTES