CO Oxidation and Oxygen Transport Characteristics of Three-Way Catalyst Microparticles Membrane for Gasoline Particulate Filter

Gasoline particulate filters with integrated three-way catalyst membranes provide simultaneous filtering and conversion, however requiring structure optimization for performance. This study investigates the influence of membrane fabrication parameters on the structure of TWC microparticles and correlation between CO oxidation performance and oxygen mass transport in TWC microparticles using isotope labeling. TWC microparticles were ultrasonically atomized into 1–2 µm spherical microparticles, and CO oxidation was evaluated at various metal loadings and firing temperatures. The T 100 for CO oxidation using TWC microparticles fired at 800 °C and 900 °C increased by 20 °C and 25 °C, respectively, compared to the unfired particles, showing active-site sintering. While doubling and quadrupling precious-metal loading decreased T 100 by 5 °C and 20 °C compared to the standard loading, respectively. TWC/GPF integration decreased T 50 by 49 °C relative to standard TWC microparticles for the 900 °C-fired case, contrarily, the T 100 increased by 56 °C due to short contact time between the gas and the catalyst for the TWC/GPF membrane than for the TWC microparticles. Measurements of the oxygen isotope distribution in TWC microparticles show that 18 O is uniformly distributed within both the cross-section and surface at locations where the CeO 2 –ZrO 2 (CZ) is present. On the other hand, the surface exhibits a higher 18 O concentration compared to the cross-section of the microparticles, indicating that while both the surface and internal precious metals in TWC microparticles contribute to the purification reaction, the surface plays a more effective role. Furthermore, the 18 O concentration also increased with an increase in the precious metal content.