Preferentially “zone coating” Pd catalyst in the front of the TWC helps reduce the time to oxidize hydrocarbons. Republished with permission of SAE International, from Development of Advanced Zone-Coated Three-Way Catalysts, Y. Aoki, S. Sakagami, M. Kawai, N. Takahashi, T. Tanabe and T. Sunada, SAE Technical Paper, 2011, 2011-01-0296, Copyright © 2011.