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Title: On the hydrothermal stability of Cu/SSZ-13 SCR catalysts

Cu/SSZ-13 SCR catalysts have been extensively studied in the past decade or so. Hydrothermal stability of these catalysts has been identified as the most important criterion for application. In this perspective, we describe recent atomic-level understanding of their hydrothermal stability. In particular, electron paramagnetic resonance (EPR) is shown to rather accurately quantify isolated Cu(II) ions and CuO clusters in fresh and aged catalysts to demonstrate the remarkable hydrothermal stability for Cu 2+ ions located in 6-membered ring windows, and the conversion of [Cu(OH)] + ions in Chabazite cages to CuO clusters. The hydrothermal stability difference of the two isolated Cu(II) ions is confirmed with DFT simulations and the conversion of [Cu(OH)] + to CuO is proposed to involve formation, migration and condensation of Cu(OH) 2 intermediates. The structural destructive role of CuO clusters is attributed to mesopore formation from their migration, which more severely damages the catalysts than dealumination. Lastly, perspectives are given on new strategies for low-temperature NO x removal, rational design and refinement of Cu/SSZ-13, and development of new Cu/zeolite SCR catalysts with even better performance than the state-of-the-art Cu/SSZ-13.
Authors:
 [1] ;  [1]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Inst. for Integrated Catalysis
Publication Date:
Report Number(s):
PNNL-SA-132960
Journal ID: ISSN 0926-860X; PII: S0926860X18302126
Grant/Contract Number:
AC05-76RL01830
Type:
Accepted Manuscript
Journal Name:
Applied Catalysis. A, General
Additional Journal Information:
Journal Volume: 560; Journal Issue: C; Journal ID: ISSN 0926-860X
Publisher:
Elsevier
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V); USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Chabazite; SSZ-13; Hydrothermal aging; Selective catalytic reduction; NOx
OSTI Identifier:
1437018