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Automotive three-way catalysts (TWC) were characterized using temperature-programmed reduction (TPR), x-ray diffraction (XRD), Raman spectroscopy, chemisorption measurements and laboratory activity measurements. Capabilities and limitations of these standard analytical techniques for the characterization of production-type automotive catalysts are pointed out. With the exception of chemisorption techniques, all appear to have general utility for analyzing exhaust catalysts. The techniques were used to show that the noble metals and ceria in fresh Pt/Rh and Pd/Rh catalysts are initially highly dispersed and contain a mixture of interacting and non-interacting species. Thermal aging of these catalysts (in the reactor or vehicle) caused both precious metal and ceria particles to sinter, thereby decreasing the interaction between the two.

A novel non-phosphorus antiwear additive, NP-1, was evaluated as a partial substitute for zinc dialkyldithiophosphate (ZDTP). ZDTP, an antiwear/antioxidant engine oil additive may under certain conditions cause three way catalyst (TWC) deactivation due to formation of an amorphous zinc pyrophosphate, Zn2P2O7, glaze. Antiwear and antioxidant properties of NP-1 alone and in combination with ZDTP were compared with ZDTP only containing formulations. The effects of NP-1 on TWC activity during pulsator modulation and steady-state conditions showed that the TWC maintained good overall activity during 24,000 simulated miles.