The Formation of Well Defined Surface Carbonyls of RU and IR with Highly Dealuminated Zeolite Y as Matrix

Burkhardt, I.; Landmesser, H.; Gutschick, D.; Mießner, H.

doi:10.1016/s0167-2991(08)61572-4

Cited by 12 publications

(13 citation statements)

References 30 publications

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“…Taking into account the behavior of the bands at 2104 and 2033 cm -1 and in agreement with literature data, ,, we assigned them to the symmetric and antisymmetric modes, respectively, of Ir + (CO) 2 species. For convenience, the assignments of all carbonyl bands observed in this study are summarized in Table .…”

Section: Resultssupporting

confidence: 78%

“…They also distinguished two types of these species: a set of bands at 2088 and 2003 cm -1 and a set of bands at 2102 and 2020 cm -1 , depending on the presence of water on the sample. Bukhardt et al also observed Ir + (CO) 2 species on their Ir/DAY (dealuminated FAU) sample (bands at 2108 and 2037 cm -1 ). The dicarbonyl structure was unambiguously established by means of 12 CO− 13 CO coadsorption.…”

Section: Introductionmentioning

confidence: 90%

“…The dicarbonyl structure was unambiguously established by means of 12 CO− 13 CO coadsorption. They observed no CO adsorption on an oxidized sample (Ir 3+ −DAY) and detected the dicarbonyl species only after reduction of the sample with CO . The remarkable analogy between the carbonyls of iridium and rhodium is worth noting.…”

Section: Introductionmentioning

confidence: 99%

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New Types of Nonclassical Iridium Carbonyls Formed in Ir-ZSM-5: A Fourier Transform Infrared Spectroscopy Investigation

et al. 2006

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In this work we report some new nonclassical carbonyls of iridium formed after CO adsorption on Ir-ZSM-5 (Ir-MFI). Mainly Ir+ cations were found on sample activated at 523 K and reduced by CO at the same temperature. With CO they formed Ir+(CO)2 gem-dicarbonyls (2104 and 2033 cm(-1)) that decomposed at 673 K without leaving a measurable fraction of monocarbonyls. The dicarbonyl structure was established by 12CO-13CO coadsortpion experiments. In the presence of CO in the gaseous phase and at ambient temperature the Ir+(CO)2 dicarbonyls were converted into Ir+(CO)3 species (2182, 2099, and 2074 cm(-1)). At 100 K these complexes are able to accommodate a fourth CO molecule thus producing tetracarbonyls (2155, 2145, 2125, and 2105 cm(-1)). The results are explained by the high coordinative unsaturation of the Ir+ cations in the ZSM-5 matrix. This is also the reason for the formation of mixed Ir+(H2O)(CO)2 species after CO-H2O coadsorption (2087 and 2015 cm(-1)). Evacuation of the sample at 673 K, followed by treatment with CO at 523 K, generates Ir2+ cations. With CO these cations form another kind of geminal complex, namely, Ir2+(CO)2 species (2173 and 2129 cm(-1)). Here again, the structure was confirmed by 12CO-13CO coadsortpion experiments. These dicarbonyls are decomposed at 573 K (again without producing monocarbonyls) and are able to accommodate additionally neither CO nor water molecules. The results are explained by the smaller cationic radius of Ir2+ (as compared to Ir+), which is associated with a decrease of the number of ligands required for coordinative saturation.

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Section: Resultssupporting

confidence: 78%

Section: Introductionmentioning

confidence: 90%

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New Types of Nonclassical Iridium Carbonyls Formed in Ir-ZSM-5: A Fourier Transform Infrared Spectroscopy Investigation

et al. 2006

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“…Concomitantly, ν CO bands grew in at 1996 and 2075 cm –1 when the support was γ-Al 2 O 3 and at 2035 and 2106 cm –1 when the support was zeolite Hβ (Figure ). These bands are assigned to iridium gem -dicarbonyls (the lower and higher frequencies are the result of the asymmetric and symmetric stretching of the two carbonyl ligands, respectively). − …”

Section: Resultsmentioning

confidence: 99%

Oxide- and Zeolite-Supported Isostructural Ir(C₂H₄)₂ Complexes: Molecular-Level Observations of Electronic Effects of Supports as Ligands

Aydin

Browning

et al. 2012

Langmuir

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Zeolite Hβ- and γ-Al(2)O(3)-supported mononuclear iridium complexes were synthesized by the reaction of Ir(C(2)H(4))(2)(acac) (acac is acetylacetonate) with each of the supports. The characterization of the surface species by extended X-ray absorption fine structure (EXAFS) and infrared (IR) spectroscopies demonstrated the removal of acac ligands during chemisorption, leading to the formation of essentially isostructural Ir(C(2)H(4))(2) complexes anchored to each support by two Ir-O(support) bonds. Atomic-resolution aberration-corrected scanning transmission electron microscopy (STEM) images confirm the spectra, showing only isolated Ir atoms on the supports with no evidence of iridium clusters. These samples, together with previously reported Ir(C(2)H(4))(2) complexes on zeolite HY, zeolite HSSZ-53, and MgO supports, constitute a family of isostructural supported iridium complexes. Treatment with CO led to the replacement of the ethylene ligands on iridium with CO ligands, and the ν(CO) frequencies of these complexes and white line intensities in the X-ray absorption spectra at the Ir L(III) edge show that the electron density on iridium increases in the following order on these supports: zeolite HY < zeolite Hβ < zeolite HSSZ-53 ≪ γ-Al(2)O(3) < MgO. The IR spectra of the iridium carbonyl complexes treated in flowing C(2)H(4) show that the CO ligands were replaced by C(2)H(4), with the average number of C(2)H(4) groups per Ir atom increasing as the amount of iridium was increasingly electron-deficient. In contrast to the typical supported catalysts incorporating metal clusters or particles that are highly nonuniform, the samples reported here, incorporating uniform isostructural iridium complexes, provide unprecedented opportunities for a molecular-level understanding of how supports affect the electronic properties, reactivities, and catalytic properties of supported metal species.

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“…The DRIFTS spectrum of CO adsorbed on the 1% Ir/saponite sample exhibits two bands at 2203 and 2095 cm –1 together with a shoulder at low wavenumbers. Similar to Rh, during CO adsorption on Ir-containing catalysts, Ir + (CO) 2 complexes are formed − with the antisymmetric stretching vibration frequency at 2095 cm –1 and the symmetric frequency at 2037 cm –1 . Two bands at 2064 and 2023 cm –1 indicate the formation of two different CO species linearly adsorbed on the surface of iridium metal particles.…”

Section: Resultsmentioning

confidence: 99%

Decalin Ring Opening on Heterogeneous Me/Saponite Nanocatalysts (Me = Rh, Ru, and Ir)

Финашина

Avaev

Ткаченко

et al. 2021

Ind. Eng. Chem. Res.

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Heterogeneous nanocatalysts containing metal nanoparticles (Me = Ir, Rh, and Ru) deposited on mesoporous saponite (magnesium aluminosilicate) were prepared from metal chlorides by the incipient wetness impregnation method and tested in the ring-opening reaction at high pressures using decalin as a substrate. The elemental composition of the catalysts and the carrier, the surface area, pore size and pore volume, the charge state, the size of metal nanoparticles, and the acidity were characterized by the following methods: scanning electron microscopy with energy-dispersive X-ray analysis, nitrogen adsorption–desorption analysis, Fourier-transform infrared spectroscopy, diffuse-reflectance Fourier-transform infrared spectroscopy, transmission electron microscopy, CO chemisorption, X-ray photoelectron spectroscopy, and X-ray diffraction analysis. It was shown that the structure of the carrier and the mesopore system were preserved after metal deposition. Metal particles have an extremely small size and high dispersion. The carrier has a small number of Brønsted acid sites (BAS), which decreases when the metal is supported. The highest BAS/LAS (Lewis acid sites) ratio is determined for the Rh/saponite catalyst. It was found that the activity, selectivity, and product composition were mostly affected by the metal nature. The Ir/saponite catalyst provides a selectivity of about 90% for the ring-opening products, both full and partial ring opening, at the total decalin conversion of about 80%. Over the Rh/saponite catalyst, up to 30% of the bicyclic products of the skeletal isomerization of decalin are formed along with the ring-opening products (mainly partial). The formation of a large number of C1–C9 hydrocracking products is observed over the Ru/saponite catalyst, besides the ring-opening products. Changes in the activity and selectivity of the catalysts with the variation of the main reaction parameters (T, P, WHSV, H2/C10 M ratio, and decalin partial pressure) were also determined.

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The Formation of Well Defined Surface Carbonyls of RU and IR with Highly Dealuminated Zeolite Y as Matrix

Cited by 12 publications

References 30 publications

New Types of Nonclassical Iridium Carbonyls Formed in Ir-ZSM-5: A Fourier Transform Infrared Spectroscopy Investigation

New Types of Nonclassical Iridium Carbonyls Formed in Ir-ZSM-5: A Fourier Transform Infrared Spectroscopy Investigation

Oxide- and Zeolite-Supported Isostructural Ir(C₂H₄)₂ Complexes: Molecular-Level Observations of Electronic Effects of Supports as Ligands

Decalin Ring Opening on Heterogeneous Me/Saponite Nanocatalysts (Me = Rh, Ru, and Ir)

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The Formation of Well Defined Surface Carbonyls of RU and IR with Highly Dealuminated Zeolite Y as Matrix

Cited by 12 publications

References 30 publications

New Types of Nonclassical Iridium Carbonyls Formed in Ir-ZSM-5: A Fourier Transform Infrared Spectroscopy Investigation

New Types of Nonclassical Iridium Carbonyls Formed in Ir-ZSM-5: A Fourier Transform Infrared Spectroscopy Investigation

Oxide- and Zeolite-Supported Isostructural Ir(C2H4)2 Complexes: Molecular-Level Observations of Electronic Effects of Supports as Ligands

Decalin Ring Opening on Heterogeneous Me/Saponite Nanocatalysts (Me = Rh, Ru, and Ir)

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Oxide- and Zeolite-Supported Isostructural Ir(C₂H₄)₂ Complexes: Molecular-Level Observations of Electronic Effects of Supports as Ligands