Durability of Platinum-Containing Automotive Exhaust Control Catalysts IMPROVEMENTS IN RESISTANCE TO THERMAL DEGRADATION

Since the introduction in I974 of catalytic converters for automotive emission control i n 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 h igh . 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 i n the catalyst. As a result a new generation o~f catalysts has now been developed with substantially improved thermal stability.