In Situ TEM Study of Rh Particle Sintering for Three-Way Catalysts in High Temperatures
1
N.E. CHEMCAT Corporation, Numazu 410-0314, Japan
2
Department of Applied Physics, Tohoku University, Sendai 980-8579, Japan
3
National Institute for Materials Science, Tsukuba 305-0044, Japan
4
Graduate School of Science and Technology, Saitama University, Shimo-Okubo 338-8570, Japan
*
Author to whom correspondence should be addressed.
Catalysts 2021, 11(1), 19; https://doi.org/10.3390/catal11010019
Received: 4 December 2020
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Revised: 19 December 2020
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Accepted: 21 December 2020
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Published: 26 December 2020
(This article belongs to the Section Environmental Catalysis)
One of the main factors in the deterioration of automobile three-way catalysts is the sintering of platinum group metals (PGMs). In this study, we used in situ tunneling electron microscopy (TEM) to examine the sintering of Rh particles as the temperature increases. Two types of environmental conditions were tested, namely, vacuum atmosphere with heating up to 1050 °C, and N2 with/without 1% O2 at 1 atm and up to 1000 °C. Under vacuum, Rh particles appeared to be immersed in ZrO2. In contrast, at 1 atm N2 with or without 1% O2, the sintered Rh particles appeared spherical and not immersed in ZrO2. The latter trend of Rh sintering resembles the actual engine-aged catalyst observed ex situ in this study. In the N2 atmosphere, the sintering of support material (ZrO2 or Y-ZrO2) was first observed by in situ TEM, followed by Rh particle sintering. The Rh particle size was slightly smaller on Y-ZrO2 compared to that on ZrO2. To better understand these experimental results, density functional theory was used to calculate the systems’ junction energies, assuming three layers of Rh(111) 4 × 4 structures joined to the support material (ZrO2 and Y-ZrO2). The calculated energies were consistent with the in situ TEM observations in the N2 atmosphere.
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Keywords:
in situ TEM; Rh sintering; DFT calculation; automotive catalyst; SMSI (strong metal-support interaction)
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MDPI and ACS Style
Nakayama, H.; Nagata, M.; Abe, H.; Shimizu, Y. In Situ TEM Study of Rh Particle Sintering for Three-Way Catalysts in High Temperatures. Catalysts 2021, 11, 19. https://doi.org/10.3390/catal11010019
AMA Style
Nakayama H, Nagata M, Abe H, Shimizu Y. In Situ TEM Study of Rh Particle Sintering for Three-Way Catalysts in High Temperatures. Catalysts. 2021; 11(1):19. https://doi.org/10.3390/catal11010019
Chicago/Turabian StyleNakayama, Hiroki, Makoto Nagata, Hideki Abe, and Yukihiro Shimizu. 2021. "In Situ TEM Study of Rh Particle Sintering for Three-Way Catalysts in High Temperatures" Catalysts 11, no. 1: 19. https://doi.org/10.3390/catal11010019
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