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In this paper, the effects of the precious metals composition in the double-layer washcoat TWC were examined by the conversion efficiency and the catalytic reaction. The double-layer tri-metal three-way catalyst (TWC) was designed to achieve a high conversion performance and a high thermal durability. The catalytic performance on the PMs loading weight was impacted by the dispersion of the PMs in washcoats. In the results of the CO-pulse chemisorption experiment, the over amount of the optimum PMs loading weight decreases the PMs dispersion in washcoats and the catalytic performance. This was accelerated on the thermal aged catalyst. TPD (temperature-programmed desorption), TPR (temperature-programmed reduction), TEM (transmission electron microscope) and BET analysis were conducted to discuss the effect of the double-layer on both the catalytic reaction and thermal stability.

In this study, experiments have been conducted to investigate parameters that effect the catalytic reaction of methane. Parameters considered were catalysts, catalyst additives, space velocity and exhaust gas components (NO, CO, H2O, O2, CO2). Catalysts used in the experiment were Pd and Pt metal loaded on γ-Al2O3 on a cordierite monolith. Methane conversion efficiency was improved for the Pd series catalyst with additive of La and Zr. With Pd/Pt catalyst, the presence of nitric oxide and water vapor showed an inhibitory effect on methane oxidation. Methane conversion efficiency decreased rapidly over 60000 h-1 space velocity.