1
|
Radhakrishnan S, Smet S, Chandran CV, Sree SP, Duerinckx K, Vanbutsele G, Martens JA, Breynaert E. Prediction of Cu Zeolite NH 3-SCR Activity from Variable Temperature 1H NMR Spectroscopy. Molecules 2023; 28:6456. [PMID: 37764230 PMCID: PMC10537069 DOI: 10.3390/molecules28186456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 08/28/2023] [Accepted: 09/04/2023] [Indexed: 09/29/2023] Open
Abstract
Selective catalytic reduction (SCR) of NOx by ammonia is one of the dominant pollution abatement technologies for near-zero NOx emission diesel engines. A crucial step in the reduction of NOx to N2 with Cu zeolite NH3-SCR catalysts is the generation of a multi-electron donating active site, implying the permanent or transient dimerization of Cu ions. Cu atom mobility has been implicated by computational chemistry as a key factor in this process. This report demonstrates how variable temperature 1H NMR reveals the Cu induced generation of sharp 1H resonances associated with a low concentration of sites on the zeolite. The onset temperature of the appearance of these signals was found to strongly correlate with the NH3-SCR activity and was observed for a range of catalysts covering multiple frameworks (CHA, AEI, AFX, ERI, ERI-CHA, ERI-OFF, *BEA), with different Si/Al ratios and different Cu contents. The results point towards universal applicability of variable temperature NMR to predict the activity of a Cu-zeolite SCR catalyst. The unique relationship of a spectroscopic feature with catalytic behavior for zeolites with different structures and chemical compositions is exceptional in heterogeneous catalysis.
Collapse
Affiliation(s)
- Sambhu Radhakrishnan
- Centre for Surface Chemistry and Catalysis—Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- NMR/X-ray Platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - Sam Smet
- Centre for Surface Chemistry and Catalysis—Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - C. Vinod Chandran
- Centre for Surface Chemistry and Catalysis—Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- NMR/X-ray Platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - Sreeprasanth Pulinthanathu Sree
- Centre for Surface Chemistry and Catalysis—Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - Karel Duerinckx
- Centre for Surface Chemistry and Catalysis—Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- NMR/X-ray Platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - Gina Vanbutsele
- Centre for Surface Chemistry and Catalysis—Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - Johan A. Martens
- Centre for Surface Chemistry and Catalysis—Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- NMR/X-ray Platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - Eric Breynaert
- Centre for Surface Chemistry and Catalysis—Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- NMR/X-ray Platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| |
Collapse
|