Chemistry of silica supported chromium ions. II. One-ligand complexes. Adsorption of carbon monoxide, carbon dioxide, and pyridine

Zecchina, Adriano; Garrone, Edoardo; Ghiotti, G.; Coluccia, S.

doi:10.1021/j100577a006

Cited by 107 publications

(78 citation statements)

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“…As such, it can be assumed that they are due to CO adsorbed on Pd. [32][33][34][35][36] The same behavior was previously observed with the Pd-W/ Al 2 O 3 catalyst. 25 Additionally, there is a decrease in the probability of having two adjacent Pd atoms binding CO in a bridging manner.…”

Section: Co and No Adsorption Measurementssupporting

confidence: 63%

Pd-W and Pd-Mo catalysts for NO decomposition and NO/CO reduction reactions

Dallago¹,

Baibich²

2009

J. Braz. Chem. Soc.

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Pd/γ-Al 2 O 3 catalysts with two different metal particle sizes were prepared from [Pd(acac) 2 ]. Subsequently, the photochemical reaction of [M(CO) 6 ] (M = Mo or W) in the presence of Pd/γ-Al 2 O 3 was used to prepare bimetallic Pd-M/γ-Al 2 O 3 catalysts. DRIFTS FTIR spectra of the catalyst surfaces prior to thermal decomposition showed unstable subcarbonyl [M(CO) n ] species. Chemisorption and CO/NO adsorption results indicated a blockage of the Pd active sites when the second metal was incorporated. The catalytic activity and the selectivity for the NO/CO reaction were higher for Pd with higher particle size, but they were both inhibited when Mo or W were incorporated. On the other hand, when the catalysts were tested for NO decomposition, the presence of Mo or W led to an increase in the catalytic activity, with optimal results observed in the presence of Mo.

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Section: Co and No Adsorption Measurementssupporting

confidence: 63%

Pd-W and Pd-Mo catalysts for NO decomposition and NO/CO reduction reactions

Dallago¹,

Baibich²

2009

J. Braz. Chem. Soc.

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“…This was in agreement with EPR spectra that showed no Cr signal since Cr ?2 is EPR silent, although it is d4 and paramagnetic in most chemical environments [21]. Chemical probing of the reduced surface sites with CO-IR studies suggested that two surface Cr ?2 and one surface Cr ?3 site may be present after CO reduction [22]. Other studies concluded that even more reduced surface Cr sites may be present [9, 12, 13, 23- Table 1).…”

Section: Activation Of Cro X /Sio 2 Catalysts With Comentioning

confidence: 86%

The Nature of Surface CrOx Sites on SiO2 in Different Environments

Chakrabarti

Wachs

2014

Catal Lett

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“…Since the oxidized high-temperature precursor state was described by the dichromate structure, the formation of low-valent Cr ion pairs on the support surface seems to be plausible. On adsorption of CO at a coverage corresponding to a 1: 1 ratio for Cr: CO three carbonyl stretching vibrations at 2191, 2186 and 2181 cm-1 were observed [263], which can be assigned to three types of linear Cr-CO complexes, namely a C~ + -CO complex (2191 cm -1) and two different 0.2+ -CO complexes (2186 and 2181 cm-1 ). At higher coverages (Cr:CO > 1), CO also adsorbs in a bridging form which gives rise to a band at 2095 cm -1.…”

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confidence: 94%