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In this paper, we studied the influence of support materials on Pd in three-way catalysts for the aim of enhancing the durability of Pd, particularly CO and NOx conversion efficiencies which are usually seriously damaged after aging. Since the durability of precious metals was found to be strongly influenced by the support material chosen, it should be possible to optimize catalyst performance by finding the appropriate support. The performance of Pd three-way catalysts with different support materials (Aluminum oxide, Cerium - Zirconium Oxide, Cerium - Zirconium -Yttrium Oxide, Zirconium Oxide, or Titanium Oxide) was compared after high temperature agings under various gas conditions. To assess Pd deterioration, the crystallite size of Pd was measured with XRD and the micro surface was observed by FE-SEM. The performance of the catalysts was evaluated.

The catalytic performance and On-Board Diagnostics (OBD) of the manifold catalyst having high Oxygen Storage Capacity (OSC) are described in this paper. First of all, we compared the performance of three-way catalysts containing Cerium - Zirconium - Yttrium oxide with Cerium - Zirconium oxide. Three-way catalysts dispersed Pt, Rh and Pd on Cerium - Zirconium - Yttrium oxide showed excellent catalytic performance especially at cold starting and at transient states, after high temperature aging at 1050°C. The performance of these catalysts was studied using the Driving Mode Simulation Dynamometer, which was developed in-house, and oxygen storage and release responses were compared in actual gas. Then we investigated the possibility of on-board diagnostics of catalyst deactivation with high OSC in manifold and close-coupled positions, a diagnostic which is usually assumed to be difficult to attain with present conventional technology.