The Development of Low Precious-Metal, Rare-Earth Oxide (REO) Catalysts for Vehicle Emission Control in Emerging Markets 2001-01-0225

Low-cost automotive catalysts have been developed that contain 20-30% of the precious metals (7-15 g/ft³) commonly used in conventional catalysts, while providing a high efficiency of emissions control and durability for vehicles operating in emerging market countries. These catalysts were reformulated by replacing the Pd, Pt and Rh mixtures with optimized mixtures of rare-earth oxides (REOs). Laboratory studies demonstrated that these aged REO catalysts (80,000 km) with unleaded Chinese fuels reduce vehicle emissions by an average of 99%, 80% and 92% for CO, HC and NOx, respectively, when operating as a three-way catalyst in a closed-loop control mode at a stoichiometric air-to-fuel ratio. REO catalysts with 7.6g/ft³ of precious metals were tested on in-use Chinese Volkswagen Santanas with carbureted engine. Several strategies for air injection were tested on these vehicles. Emissions were reduced by an average of 70% for CO, 55% for HC and 30% for NOx using the ECE 15.04 drive cycle. The retrofit of in-use vehicles with REO catalysts can be effective when a system approach that includes a vigorous I/M program, the right catalyst for a required conversion rate, proper location to place the catalyst and fuel quality.