Evaluation of New Mixed Oxides for Use as Sulfur Tolerant Exhaust Gas Catalysts. Third Annual Report (1 June 2000-30 May 2001).

摘要

The interaction of CO with Ce O2, CD O2-Zr O2, Zr O2, as pure materials and supporting 1% Pd, has been investigated by in situ Raman and infrared spectroscopy. The goal of these investigations was to understand the factors that may affect the accuracy of conventional oxygen storage capacity (OSC) measurements. It has been established that surface carbonates and formates form on the CeO2, CeO2-ZrO2 and ZrO2, both with and without Pd. The sulfur tolerance of 1% Pd/CeO2 and 1% Pd/CeO2-ZrO2 catalysts under lean, stoichiometric, and cyclic conditions relevant to TWC has also been investigated. The 1% Pd/CeO2-ZrO2 is more sulfur tolerant than Pd/CeO2. The presence of sulfur dioxide leads to lower rate of No-x reduction under cyclic conditions than under lean conditions.