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Effect of the Nature and Location of Copper Species on the Catalytic Nitric Oxide Selective Catalytic Reduction Performance of the Copper/SSZ‐13 Zeolite
Author(s) -
Guo Qiang,
Fan Fengtao,
Ligthart D. A. J. Michel,
Li Guanna,
Feng Zhaochi,
Hensen Emiel J. M.,
Li Can
Publication year - 2014
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201300775
Subject(s) - copper , zeolite , chabazite , chemistry , catalysis , inorganic chemistry , selective catalytic reduction , raman spectroscopy , organic chemistry , physics , optics
The nature and location of copper in Cu/SSZ‐13 zeolites synthesized by using a one‐pot hydrothermal approach with Cu–tetraethylenepentamine as a template and by the ion exchange of SSZ‐13 were investigated by applying H 2 ‐temperature‐programmed reduction, FTIR, EPR, and in situ Raman spectroscopic techniques. The one‐pot synthesized Cu/SSZ‐13 zeolite contains predominantly isolated copper ions in the large cages, whereas copper species in the ion‐exchanged Cu/SSZ‐13 zeolite occupy sites in the large cages of the chabazite (CHA) structure and the six‐membered rings of the CHA structure. If the one‐pot synthesized Cu/SSZ‐13 zeolite is exchanged with the NH 4 NO 3 solution in addition to the removal of a part of copper ions, the remaining copper ions in the CHA structure relocated from the large cages to the six‐membered rings. Isolated copper dominated in all Cu/SSZ‐13 zeolites. The in situ Raman spectra demonstrated that CuOCu dimers form at higher copper content. The bis‐μ‐oxo dicopper(III) complex is observed only in the ion‐exchanged sample upon dehydration. The higher NO selective catalytic reduction activity of the one‐pot synthesized sample in a wide temperature range appears to be due to the predominance of isolated Cu 2+ sites in the large cages, and their higher reactivity is possibly owing to the lower stability of Cu 2+ at these sites.