Experimental and Computational Interrogation of Fast SCR Mechanism and Active Sites on H-Form SSZ-13
Experiment and density functional theory (DFT) models are combined to develop a unified, quantitative model of the mechanism and kinetics of fast selective catalytic reduction (SCR) of NO/NO2 mixtures over H-SSZ-13 zeolite. Rates, rate orders, and apparent activation energies collected under differential conditions reveal two distinct kinetic regimes. First-principles thermodynamics simulations are used to determine the relative coverages of free Brønsted sites, chemisorbed NH4+ and physisorbed NH3 as a function of reaction conditions. First-principles metadynamics calculations show that all three sites can contribute to the rate-limiting N-N bond forming step in fast SCR. The results are used to parameterize a kinetic model that encompasses the full range of reaction conditions and recovers observed rate orders and apparent activation energies. Observed kinetic regimes are related to changes in most-abundant surface intermediates. Financial support was provided by the National Science Foundation GAOLI program under award number 1258690-CBET. We thank the Center for Research Computing at Notre
- 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:
- 1398190
- Report Number(s):
- PNNL-SA-125720; 47953; 48807; VT0401000
- Journal Information:
- ACS Catalysis, Vol. 7, Issue 8; ISSN 2155-5435
- Publisher:
- American Chemical Society (ACS)
- Country of Publication:
- United States
- Language:
- English
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