Nickel-Copper Alloy Nox Reduction Catalysts for Dual Catalyst Systems 730567
Latest results with dual catalyst systems incorporating GEM nickel-copper alloy NOx reduction catalysts are reported. Progress in optimizing system design to provide rapid warmup, maintenance of operating temperature, and controlled carburetion to maximize NOx removal and minimize the risk of over-temperature is discussed. Results of vehicle durability tests of GEM catalysts run on dynamometers are also presented.
Rapid warmup of the catalyst system can be obtained by keeping NOx reduction catalyst mass low and utilizing the ability of the reduction catalyst to oxidize CO, H2, and HC under net reducing conditions. This ability to oxidize CO, H2, and HC is also used to maintain system operating temperature. Carburetion is controlled to ±0.4 A/F with a four-barrel research carburetor, the design of which is described in detail. The research carburetor does not contain a power valve which helps minimize the risk of over-temperature, but an over-temperature safety or warning device will probably be necessary in the final system.
Durability results presented in this paper show a significant improvement over the published state-of-the-art for NOx reduction catalysts.