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Ceria PNA TWC NO OX.pdf (818.09 kB)

Identification of Ru/Ceria Among Single Atom Ceria Catalysts as a Stable and Superior Material for Abatement of Diesel and Gasoline Engine Pollutants

preprint
submitted on 22.07.2020 and posted on 23.07.2020 by Konstantin Khivantsev, Nicholas R. Jaegers, Libor Kovarik, Jinshu Tian, Xavier Isidro Pereira Hernandez, Yong Wang, János Szanyi
Atomically dispersed transition metals (Ru, Pd and Pt) have been prepared on CeO2 and evaluated for NOx/CO abatement applications for diesel and gasoline engines, such as low temperature passive NOx adsorption (PNA), NO and CO oxidation, and three-way-catalysis (TWC). 0.5 wt% Ru/CeO2 catalyst (Ru is ~27 and ~7 times cheaper than Rh and Pd) shows remarkable PNA performance, better than 1 wt% Pd/Zeolite: it achieves 100% removal of NOx during vehicle cold start. FTIR measurements reveal the formation of stable Ru(NO) complexes as well spill-over of NO to CeO2 surface via the Ru-O-Ce shuttle, explaining high NO storage. Notably, Ru/ceria survives hydrothermal aging at 750 ⁰C without loss of PNA capacity. It is also a robust NO oxidation catalyst, considerably more active than Pt or Pd/CeO2. Expanding the repertoire of Ru/CeO2 catalytic applications, we further find 0.1 and 0.5 wt% Ru/CeO2 to be excellent TWC catalysts, rivaling best single-atom Rh supported materials. Our study pushes the frontier of precious metal atom economy for environmental catalysis from uber expensive Rh/Pd/Pt to more sustainable cheaper Ru and highlights the utility of single-atom catalysts for industrially relevant applications.

Funding

The research at PNNL was supported by the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Vehicle Technology Office. Experiments were conducted in the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy’s Office of Biological and Environmental Research at Pacific Northwest National Laboratory (PNNL). PNNL is a multi-program national laboratory operated for the DOE by Battelle Memorial Institute under Contract DE-AC06-76RL01830. We acknowledge the support of CLEERS (Crosscut Lean Exhaust Emissions Reduction Simulations). CLEERS is an initiative funded by the U.S. Department of Energy (DOE) Vehicle Technologies Office to support the development of accurate tools for use in the design, calibration, and control of next generation engine/emissions control systems that maximize efficiency while complying with emissions regulations.

History

Email Address of Submitting Author

Konstantin.Khivantsev@pnnl.gov

Institution

Pacific Northwest National Laboratory

Country

United States

ORCID For Submitting Author

0000-0002-4810-586X

Declaration of Conflict of Interest

The authors filed for a patent

Version Notes

Version 1.0

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