Coordination of Cu Ions in High-Silica Zeolite Matrixes. Cu+ Photoluminescence, IR of NO Adsorbed on Cu2+, and Cu2+ ESR Study

Dědeček, Jiřı́; Sobalı́k, Zdenĕk; Tvaruazkova, Z.; Kaucký, Dalibor; Wichterlová, Blanka

doi:10.1021/j100044a020

Cited by 255 publications

(215 citation statements)

References 6 publications

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“…This g i value can be assigned to Cu 2+ ions in a distorted octahedral coordination sphere containing only oxygen atoms. [15,32,33] These results are in agreement with the results observed in the UV-vis spectra.…”

Section: Resultssupporting

confidence: 91%

Investigation of the Structure of MCM‐41 Samples with a High Copper Content

Kong

Zhu

Yang

et al. 2004

Adv Funct Materials

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A series of MCM‐41s with a high copper content were synthesized at room temperature from sodium metasilicate (Na2SiO3) as the silicon source, tetraamminecopper(II) nitrate [Cu(NH3)4(NO3)2] as the copper source and cetyltrimethylammonium bromide (CTABr) as the template. The resulting material was characterized by using the following characterization techniques: X‐ray diffraction (XRD), N2‐adsorption isotherms, high‐resolution transmission electron microscopy (HRTEM), inductively coupled plasma (ICP), temperature‐programmed reduction (H2‐TPR), X‐ray photoelectron spectroscopy (XPS), Fourier‐transform infrared spectroscopy (FTIR), UV‐vis spectroscopy, electron‐spin resonance (ESR) and 29Si magic‐angle sample spinning nuclear magnetic resonance (MAS NMR) spectroscopy. The characterization techniques demonstrated the following: i) the copper atoms are incorporated into the framework of MCM‐41 and ii) the copper species in the samples are in a distorted octahedral coordination environment, with between four and six oxygen atoms in the first coordination sphere. The maximum copper content determined by ICP was 26 wt.‐% in the ordered mesoporous sample with a surface area of 525 m2 g–1 and an average pore diameter of 3.1 nm. The synthesized materials exhibited a high activity for nitrogen monoxide (NO) reduction by carbon monoxide (CO).

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Section: Resultssupporting

confidence: 91%

Investigation of the Structure of MCM‐41 Samples with a High Copper Content

Kong

Zhu

Yang

et al. 2004

Adv Funct Materials

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“…In NO and O 2 a new peak is observed at 1906 cm )1 . This peak is a combination of bands at 1900 and 1911 cm )1 , close to where peaks have been assigned to NO adsorbed on Cu 2+ ions [22,[29][30][31][32]. During exposure to 500 ppm NO without oxygen (Figure 1(a)) only very small bands between 1500 and 1650 cm )1 can be found.…”

Section: No X Adsorptionsupporting

confidence: 56%

“…The intensity of the band assigned to NO + is also decreased but instead the band at 1906 cm )1 is increased. There is a new, small band formed at 1811 cm )1 , which has been assigned to NO adsorbed on Cu + [29][30][31][32].…”

Section: No X Adsorptionmentioning

confidence: 99%

Identification of adsorbed species on Cu-ZSM-5 under NH3 SCR conditions

et al. 2007

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The selective catalytic reduction of nitrogen oxides with ammonia as the reducing agent was studied using Fourier transform infrared (FTIR) spectroscopy. The adsorbed species found on a Cu-ZSM-5 powder during exposure to NO, NO 2 or NH 3 was compared to the adsorbed species identified during SCR conditions. A blocking effect caused by ammonia at 175°C was investigated by a stepwise increase of the ammonia concentration, and the spectra indicated that the formation of nitrites or nitrates decreased as surface coverage of ammonia increased. No such effect was observed at 350°C, since the oxidation of ammonia results in very low ammonia coverage. The effect of changes in the NO to NO 2 ratio was also studied at 350°C, and the species identified during SCR reaction indicated that the enhanced activity at equimolecular amounts of NO and NO 2 possibly involves gas phase components as well as adsorbed species.

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“…10,[13][14][15] CO is known to be adsorbed on Cu-ZSM-5, even under mild conditions such as at low pressure and room temperature. [16][17][18][19][20][21][22][23] The frequency shift of CO in the adsorption complex has been used to depict the characteristic of the active site and its bonding nature. At least two types of Cu(I) species had been identified from previous IR experiments.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of Nitrogen Monoxide and Carbon Monoxide on Copper-Exchanged ZSM-5: A Cluster and Embedded Cluster Study

2001

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We present a systematic study on the adsorption of NO and CO in Cu-ZSM-5, using an ab initio embedded cluster methodology at the B3LYP level of theory. We found that the effects of the cluster size and Madelung potential are small for adsorption energies of CO and NO. For adsorption of CO, the calculated binding energy of 32 kcal/mol is in good agreement with experimental data from 29 to 32 kcal/mol. On the contrary, for adsorption of NO the calculated binding energy of 22 kcal/mol is much smaller than the experimental estimate, though it is consistent with recent experimental observation that NO binding energy should be smaller than that of CO. Madelung potential, however, is important for obtaining the correct blue shift of an adsorbed CO and red shift of an adsorbed NO.

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Coordination of Cu Ions in High-Silica Zeolite Matrixes. Cu+ Photoluminescence, IR of NO Adsorbed on Cu2+, and Cu2+ ESR Study

Cited by 255 publications

References 6 publications

Investigation of the Structure of MCM‐41 Samples with a High Copper Content

Investigation of the Structure of MCM‐41 Samples with a High Copper Content

Identification of adsorbed species on Cu-ZSM-5 under NH3 SCR conditions

Adsorption of Nitrogen Monoxide and Carbon Monoxide on Copper-Exchanged ZSM-5: A Cluster and Embedded Cluster Study

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