Bis(μ‐oxo)dicopper as Key Intermediate in the Catalytic Decomposition of Nitric Oxide

Groothaert, Marijke H.; Lievens, Kristof; Bokhoven, Jeroen A. van; Battiston, A.A.; Weckhuysen, Bert M.; Pierloot, Kristine; Schoonheydt, Robert A.

doi:10.1002/cphc.200300746

Cited by 50 publications

(53 citation statements)

References 40 publications

(9 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As proven in several works from the Schoonheydt group, 117,127,128 this last band is related to the formation of mono(μ-oxo)dicopper, i.e. The spectrum of O 2 activated Cu-ZSM-5 exhibits a peculiar tail at 22 700 cm −1 (also present but with lower intensity in the Cu-β spectrum), suggesting at least one different Cu species in addition to isolated Cu 2+ ions.…”

Section: Paper Dalton Transactionsmentioning

confidence: 64%

Characterization of Cu-exchanged SSZ-13: a comparative FTIR, UV-Vis, and EPR study with Cu-ZSM-5 and Cu-β with similar Si/Al and Cu/Al ratios

et al. 2013

View full text Add to dashboard Cite

Cu-SSZ-13 has been characterized by different spectroscopic techniques and compared with Cu-ZSM-5 and Cu-β with similar Si/Al and Cu/Al ratios and prepared by the same ion exchange procedure. On vacuum activated samples, low temperature FTIR spectroscopy allowed us to appreciate a high concentration of reduced copper centres, i.e. isolated Cu(+) ions located in different environments, able to form Cu(+)(N2), Cu(+)(CO)n (n = 1, 2, 3), and Cu(+)(NO)n (n = 1, 2) upon interaction with N2, CO and NO probe molecules, respectively. Low temperature FTIR, DRUV-Vis and EPR analysis on O2 activated samples revealed the presence of different Cu(2+) species. New data and discussion are devoted to (i) [Cu-OH](+) species likely balanced by one framework Al atom; (ii) mono(μ-oxo)dicopper [Cu2(μ-O)](2+) dimers observed in Cu-ZSM-5 and Cu-β, but not in Cu-SSZ-13. UV-Vis-NIR spectra of O2 activated samples reveal an intense and finely structured d-d quadruplet, unique to Cu-SSZ-13, which is persistent under SCR conditions. This differs from the 22,700 cm(-1) band of the mono(μ-oxo)dicopper species of the O2 activated Cu-ZSM-5, which disappears under SCR conditions. The EPR signal intensity sets Cu-β apart from the others.

show abstract

Section: Paper Dalton Transactionsmentioning

confidence: 64%

Characterization of Cu-exchanged SSZ-13: a comparative FTIR, UV-Vis, and EPR study with Cu-ZSM-5 and Cu-β with similar Si/Al and Cu/Al ratios

et al. 2013

View full text Add to dashboard Cite

show abstract

“…28 Studies using different characterization techniques identified the active center to be a bis(µ-oxo) complex similar to that present in enzyme systems. For example, Groothaert and co-workers [29][30][31] found a clear correlation between the UV-vis band and the oxidation state of copper in Cu-ZSM-5 zeolites. They assigned the observed 22 700 cm -1 UV-vis band from Cu-ZSM-5 to a bis(µ-oxo) dicopper core formed using the oxygen released during the N 2 O decomposition.…”

Section: Introductionmentioning

confidence: 99%

Geometric and Electronic Structure of α-Oxygen Sites in Mn-ZSM-5 Zeolites

et al. 2008

Self Cite

View full text Add to dashboard Cite

It is shown that R-oxygen sites are generated by the decomposition of N 2 O in ion-exchanged Mn-ZSM-5 zeolites. The catalytic activity decreases to zero in 1 h, and the amount of R-oxygen that is formed is reduced from ∼30% R-oxygen sites per Mn atom in the initial N 2 O treatment to a value of ∼4% in the subsequent cycles. The catalytic activity correlates with the intensity of a UV-vis band located at 18 500 cm -1 , suggesting that the R-oxygen sites are linked to Mn sites with a distorted tetragonal symmetry with extended Mn-O bonds with respect to bulk oxides. Scanning transmission electron microscopy with electron energy loss spectroscopy (STEM-EELS) results indicate that the Mn sites are distributed unevenly over the ZSM-5 crystals, where most Mn atoms are found in the top ∼2 nm from the crystal surface. The X-ray absorption spectroscopy (XAS) spectra indicate that, under reaction conditions, the Mn atoms have a 5-fold coordination and a valence of ∼2.5, which is little affected by the N 2 O and NO treatments as only ∼4% of these sites is active.

show abstract

“…The corresponding UV-vis-NIR spectrum is characterized by an intense CT (charge transfer) band at 22,700 cm −1 and a weak CT band at 30,000 cm −1 . For the first time, these combined EPR, XAFS, and UVvis-NIR data were compared with the large databank of well-characterized copper centers in enzymes and synthetic model complexes and led to the identification of the bis(µ-oxo)dicopper core, i.e., [Cu 2 (µ-O) 2 ] 2+ (Structure A) in calcined overexchanged Cu-ZSM-5 [47][48][49]. We showed that the catalytic NO decomposition activity and the presence of the bis(µ-oxo)dicopper core occur concomitantly, strongly suggesting a correlation [49].…”

Section: Introductionmentioning

confidence: 99%

An operando optical fiber UV–vis spectroscopic study of the catalytic decomposition of NO and N2O over Cu-ZSM-5

Groothaert

Lievens

Leeman

et al. 2003

Journal of Catalysis

Self Cite

131

View full text Add to dashboard Cite

The role of the bis(µ-oxo)dicopper core, i.e., [Cu 2 (µ-O) 2 ] 2+ , in the decomposition of NO and N 2 O by the Cu-ZSM-5 zeolite has been studied with combined operando UV-vis monitoring of the catalyst and on-line GC analysis. An optical fiber was mounted on the outer surface of the quartz wall of the plug-flow reactor and collected the UV-vis diffuse reflectance spectra under true catalytic conditions.

show abstract

Bis(μ‐oxo)dicopper as Key Intermediate in the Catalytic Decomposition of Nitric Oxide

Cited by 50 publications

References 40 publications

Characterization of Cu-exchanged SSZ-13: a comparative FTIR, UV-Vis, and EPR study with Cu-ZSM-5 and Cu-β with similar Si/Al and Cu/Al ratios

Characterization of Cu-exchanged SSZ-13: a comparative FTIR, UV-Vis, and EPR study with Cu-ZSM-5 and Cu-β with similar Si/Al and Cu/Al ratios

Geometric and Electronic Structure of α-Oxygen Sites in Mn-ZSM-5 Zeolites

An operando optical fiber UV–vis spectroscopic study of the catalytic decomposition of NO and N2O over Cu-ZSM-5

Contact Info

Product

Resources

About