Linear nanoscale clusters of CuO in Cu-ZSM-5 catalysts

Ismagilov, Z. R.; Yashnik, S. A.; Anufrienko, V. F.; Larina, T. V.; Vasenin, N. T.; Bulgakov, N. N.; Vosel, S. V.; Tsykoza, L. T.

doi:10.1016/j.apsusc.2003.11.035

Cited by 60 publications

(41 citation statements)

References 15 publications

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“…12,000-13,000/44,000-45,000 cm −1 ) and polymeric -Cu-O-Cu-(d-d band at ca. 16,000 cm −1 ) species [10][11][12]. In the 1.0Cu-ZSM-5 sample, an additional polymeric species was also observed (ca.…”

Section: Resultsmentioning

confidence: 76%

“…In other words, oxide-type Cu-containing aggregates (UV-vis band ca. 30,000 cm −1 [10][11][12]) are somewhat difficult to detect by UV-vis spectroscopy, but here they can be clearly distinguished by the presence of the signals at 297 and 347 cm −1 in the Raman spectrum of the 1.0Cu-ZSM-5 sample (Fig. 5).…”

Section: Resultsmentioning

confidence: 93%

“…Polymeric Cu species detected in ZSM-5 give distinct UV-visible signals in correspondence with the degree of reduction (Cu(II) → Cu(I)); presumably increasing with the increasing presence of "undercoordinated" surface cations. Polymeric species containing Cu + ions would display lower characteristic frequencies than the fully oxidized ones [10,11]. It is interesting to stress the absence of two Cu species in both samples, the Cu-O-Cu dimers with characteristic UV-vis frequencies around 22,500 cm −1 [12,13] and the metallic Cu clusters (hypothetically produced in the reductive atmosphere created by decomposition of the Cu precursor during catalyst preparation), which would lead to a plasmon peak at 16,000 cm −1 [14].…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Hydroxylation/oxidation of benzene over Cu-ZSM-5 systems: Optimization of the one-step route to phenol

Kubacka

Wang

Sulikowski

et al. 2007

Journal of Catalysis

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Section: Resultsmentioning

confidence: 76%

Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Hydroxylation/oxidation of benzene over Cu-ZSM-5 systems: Optimization of the one-step route to phenol

Kubacka

Wang

Sulikowski

et al. 2007

Journal of Catalysis

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“…Such a band can be attributed to ligand-to-metal CTB of Cu 2? within dimeric [14] or small oxide clusters [15]. Formation of clusters in Cu-MgO system was earlier supposed based on ESR studies.…”

Section: Resultsmentioning

confidence: 99%

Effect of anionic admixtures on the copper–magnesium mixed oxide reduction

Khassin

Filonenko

Minyukova

et al. 2010

Reac Kinet Mech Cat

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The anionic composition, structural parameters, optical properties and reduction behavior of Cu-MgO solid solution in hydrogen dramatically change after exposure to air. The air-exposed Cu-Mg oxide contains a lot of CO 3 2-and OHanions. Its reduction proceeds via two stages: (1) diffusion of Cu 2? to the surface and (2) chemical interaction of Cu 2? with hydrogen. The effective activation energy gradually increases from that of the chemical step (65 kJ/mol) to that of the transport step of Cu 2? diffusion (130 kJ/mol). This behavior follows the ''compensation effect'', which is close to those reported earlier for CuO reduction. On the contrary, reduction of Cu 2? from the Cu-Mg oxide sample, which was not exposed to air after thermal pretreatment in the inert gas, proceeds in one step at 120-160°C with the effective activation energy of 19 kJ/mol, which is manifold less than the reported effective activation energies for various Cu-oxide systems. Water molecules eliminate from the sample slowly along with further heating up to 450°C.

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“…28 In addition, CuFe-ZSM-5 has two absorptions that can be attributed to framework tetrahedral and extra-framework octahedral Fe 3+ , at 210 nm and 270 nm, respectively, as seen in Fe-ZSM-5 type structures. 15 In general, absorptions of oligomeric iron oxide clusters and iron oxide particles are believed to be above 400 nm 15 and are not seen.…”

Section: Zsm-5 Type Heterobimetallic Zeolitesmentioning

confidence: 99%