Nitrogen oxide removal catalysts for purification of automobile exhaust gases

Conference · Tue Jan 01 04:00:00 EST 1974

OSTI ID:7274092

Ashmead, D R; Campbell, J S; Davies, P; Farmery, K

The chemistry involved in the selective catalytic reduction of nitrogen oxides in automobile exhaust is outlined, and the requirements of a practical NO/sub x/ reduction catalyst are summarized. Critical reactions for the removal of NO/sub x/ are likely to be hydrogenation (with a mechanism proceeding through ammonia or some other NHn species) and/or the oxidation of carbon monoxide with the intermediary of surface N species or even isocyanates. Laboratory studies of NO/sub x/ reduction catalysts indicate the following: ruthenium is the most effective catalytic material at high values of the reducing power index of the gas mixture (i.e., high CO or low O/sub 2/ levels); rhodium is most effective over a narrow range of the reducing power index and can operate closer to stoichiometric than the other active species tested; base metal catalysts behave like Ru catalysts but require higher temperatures of operation; and platinum alone is relatively ineffective whatever the conditions of use. Limited endurance data obtained from dynamometer tests indicate it is possible to control hydrocarbons, CO, and NO/sub x/ emissions simultaneously within the old 1976 limits for at least 10,000 mi on small displacement vehicles using a dual-catalyst system.

• OSTI ID: 7274092
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
330701* -- Emission Control-- Nitrogen Oxides
AUTOMOBILES
CATALYSTS
CATALYTIC CONVERTERS
CHALCOGENIDES
CHEMICAL REACTIONS
DOCUMENT TYPES
DYNAMOMETERS
ELEMENTS
EQUIPMENT
HYDROGENATION
MEASURING INSTRUMENTS
METALS
NITROGEN COMPOUNDS
NITROGEN OXIDES
OXIDES
OXYGEN COMPOUNDS
PERFORMANCE TESTING
PLATINUM
PLATINUM METALS
POLLUTION CONTROL EQUIPMENT
REDUCTION
REFRACTORY METALS
REVIEWS
RHODIUM
RUTHENIUM
TESTING
TRANSITION ELEMENTS
VEHICLES