Durability of Platinum-Containing Automotive Exhaust Control Catalysts

Since the introduction in 1974 of catalytic converters for automotive emission control in the United States significant advances have been made in the design of durable monolith supported catalysts for the control of carbon monoxide, unburnt hydrocarbon and nitrogen oxide emissions. However, high temperature durability, has been a significant problem, particularly of three-way catalysts. Johnson Matthey Inc. have examined the fundamental nature of catalyst deactivation under high temperature conditions. This has been found to be associated with problems as diverse as adhesion of the catalyst layer to the ceramic monolith, interaction of the platinum metals with the underlying support and poor thermal stability of base metal promoters incorporated in the catalyst. As a result a new generation of catalysts has now been developed with substantially improved thermal stability.