Toward Rational Design of Cu/SSZ-13 Selective Catalytic Reduction Catalysts: Implications from Atomic-Level Understanding of Hydrothermal Stability
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- Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99354, United States; The Gene &, Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, P.O. Box 646515, Pullman, Washington 99164, United States
- Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99354, United States
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99354, United States
The hydrothermal stability of Cu/SSZ-13 SCR catalysts has been extensively studied, yet atomic level understanding of changes to the zeolite support and the Cu active sites during hydrothermal aging are still lacking. In this work, via the utilization of spectroscopic methods including solid-state 27Al and 29Si NMR, EPR, DRIFTS, and XPS, together with imaging and elemental mapping using STEM, detailed kinetic analyses, and theoretical calculations with DFT, various Cu species, including two types of isolated active sites and CuOx clusters, were precisely quantified for samples hydrothermally aged under varying conditions. This quantification convincingly confirms the exceptional hydrothermal stability of isolated Cu2+-2Z sites, and the gradual conversion of [Cu(OH)]+-Z to CuOx clusters with increasing aging severity. This stability difference is rationalized from the hydrolysis activation barrier difference between the two isolated sites via DFT. Discussions are provided on the nature of the CuOx clusters, and their possible detrimental roles on catalyst stability. Finally, a few rational design principles for Cu/SSZ-13 are derived rigorously from the atomic-level understanding of this catalyst obtained here. The authors gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Office for the support of this work. Computing time was granted by a user proposal at the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) and by the National Energy Research Scientific Computing Center (NERSC). The experimental studies described in this paper were performed in the EMSL, a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1419918
- Report Number(s):
- PNNL-SA-128659; 47953; VT0401000
- Journal Information:
- ACS Catalysis, Vol. 7, Issue 12; ISSN 2155-5435
- Publisher:
- American Chemical Society (ACS)
- Country of Publication:
- United States
- Language:
- English
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