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Shin Inamoto, Akiyo Yoshida, Naoto Kaneko, Yuji Otsuka, B11-P-06
Three-dimensional analysis of exhaust gas catalyst using energy dispersive X-ray tomography , Microscopy, Volume 64, Issue suppl_1, November 2015, Page i80, https://doi.org/10.1093/jmicro/dfv210Close - Share Icon Share
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Noble metal particles supported on ceria, zirconia, and alumina are commonly used as exhaust gas catalysts for automobiles. The catalytic performance of these catalysts gradually degrades by long-term exposure to exhaust gas at the high temperature. In the present study, three-dimensional elemental distribution of the exhaust gas catalyst has been analyzed using energy dispersive X-ray (EDX) tomography in order to obtain the information of the catalytic degradation. The ceramic honeycomb coated with catalyst was extracted from the automobile after traveling approximately 100,000 km. The catalyst layer near the surface was milled in a rod-shape by focused ion beam (FIB) technique to reduce the overlapping of the particles along the observed direction at high-tilting angle. Elemental maps of Al, Zr, Ce, and Pd were acquired at the tilt range of ± 72 0 and the tilt increment of 8°. Figure 1 shows a three dimensional reconstruction of Al, Zr, Ce, and Pd. It can be observed that the distribution of the zirconia and the ceria-zirconia is separated clearly, although it is difficult from the STEM image reconstruction. In the aggregate of alumina, the Pd particles grow in size as indicated by arrows. These results are expected to be important information for identifying the mechanism of the catalytic degradation.
