Core@Shell Shaped Catalysts with Enhanced Low Temperature Activity for Emissions Control Applications
Περίληψη
Catalysts need to perform effectively at low exhaust temperatures to meet the strict emission standards introduced by the U.S. Environmental Protection Agency as a result of the continued improvements in vehicle engine efficiency. Therefore, U.S. DRIVE established a goal of achieving 90% conversion of hazardous emissions at 150 ºC. Diesel oxidation catalysts (DOCs) and three-way catalysts (TWCs) need to also survive hydrothermal aging at 800 oC based on the low temperature aftertreatment protocol defined by U.S. DRIVE [1]. ZrO2 and CeO2 oxide supports are widely used in the automotive industry to promote catalytic activity. However, ZrO2 and CeO2 suffer from severe deactivation due to their grain growth at elevated temperatures. Herein, SiO2 and CeO2 spheres are coated with a Zr-based layer with varying thickness. The catalytic performance of novel structured DOCs and TWCs, such as Pd/SiO2@Zr [2], bimetallic Pd/Pt/SiO2@Zr, and Pt/CeO2@Zr is explored. This work illustrates the development of bimetallic Pd/Pt/SiO2@Zr DOCs and monometallic Pt/(1-x)CeO2@xZrO2 TWCs with enhanced durability and low-temperature activity. Pt can be stabilized by forming Pd/Pt alloys and oxide solid solution phases in Pd,Pt/SiO2@Zr DOCs. Finally, incorporating a moderate amount of Zr (x = 0.1) in Pt/(1-x)CeO2@xZrO2 TWCs can improve the oxygen storage capacity complete, oxygen releasing rate and low temperature catalytic activity. The impact of the catalyst support/active metal compositions, local catalyst structure designs, aging conditions on low-temperature oxidation activity and hydrothermal stability will be discussed.
References
1. Rappé, K.G., DiMaggio, C., Pihl, J.A., Theis, J.R., Oh, S.H., Fisher, G.B., Parks, J., Easterling, V.G., Yang, M., and Stewart, M.L., Emiss. Control Sci. Technol. 5, 183-214 (2019).
2. Liu, C.-H., Chen, J., Toops, T.J., Choi, J.-S., Thomas, C., Lance, M.J., and Kyriakidou, E.A., Chem. Eng. J. 130637 (2021).
Σύντομο Βιογραφικό Ομιλητή
Dr. Eleni Kyriakidou received her BSc and MSc degrees in Chemical Engineering in 2007 from the Aristotelian University of Thessaloniki, where her interest in catalysis was sparked while performing research under Prof. Michael Stoukides. She continued to earn a full graduate fellowship from the State Scholarships Foundation of Greece and pursue and complete her Ph.D. in Heterogeneous Catalysis under the supervision of Prof. Michael D. Amiridis at the University of South Carolina in 2014 (Chemical Engineering). During her graduate studies she developed an expertise in the synthesis and characterization of highly dispersed silver, rhodium and gold supported metal catalysts. In her postdoctoral research in Oak Ridge National Laboratory, Dr. Kyriakidou advanced her catalyst synthesis skills and she developed catalytic methods to treat automobile exhausts from cold-starting engines. She started her independent scientific career at the Chemical and Biological Engineering Department at the University at Buffalo (SUNY) in January 2017, and received early promotion to the rank of Associate Professor with tenure in 2023. She leads a research group that is recognized for the production of cutting-edge catalytic materials that meet the strict emission control regulations by utilizing common pollutants from internal combustion engines and marine vessels.