期刊
APPLIED CATALYSIS A-GENERAL
卷 640, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.apcata.2022.118656
关键词
Selective catalytic reduction; Cu-SSZ-13; SCR redox half-cycle; NH3 temperature-programmed desorption; Hydrothermal aging
资金
- DOE Office of Energy Efficiency and Renewable Energy (EERE) Vehicle Technologies Office (VTO) at the National Transportation Research Center
- DOE-EERE User Facility at Oak Ridge National Laboratory
- CRADA project
In this study, the SCR reaction on Cu-SSZ-13 was investigated through experiments and kinetic modeling. It was found that RHC requires the simultaneous presence of NO and NH3, while OHC requires both NO and O2. Additionally, a previously unreported H2O-mediated OHC pathway was discovered.
The Standard SCR reaction on Cu-SSZ-13 is a complex redox process facilitated by a reduction half cycle (RHC) and an oxidation half cycle (OHC). It is generally accepted that RHC requires the simultaneous presence of NO and NH3, while OHC requires both NO and O2; however understanding of how these individual reactants impact the Cu redox cycle is limited. In this study, we provide experimental investigation of NO-only, NH3-only and NO+NH3 RHC, and their relative rates. Simple kinetic models were developed to understand the dependance of NO-only and NH3-only RHC on Cu speciation. Various OHC routes including NO+O2 and O2-only OHC, and a previously unreported H2O-mediated OHC pathway were also investigated. Detailed NH3 temperatureprogrammed desorption studies showed that RHC selectively consumes NH3 adsorbed on Lewis-acid sites, and that part of the remaining Bronsted-bound NH3 moves to the Lewis-acid sites during subsequent OHC, thereby resulting in a repartitioning of adsorbed NH3.
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