État superficiel de réduction de la cérine : étude infrarouge par adsorption du méthanol

Binet, Claude; Jadi, A.; Lavalley, J.C.

doi:10.1051/jcp/1992891441

Cited by 37 publications

(57 citation statements)

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“…Moreover, a complex pattern in the range 1700-1350 cm )1 appears and evolves by increasing the contact time. Similar spectroscopic features have been previously reported, for example, for CeO 2 [11] and ZrO 2 [12], and related to the formation of acetamide-like species by reaction of adsorbed acetonitrile molecules with surface basic centres. In the present case, the observed spectral behaviour indicates that acetonitrile molecules initially adsorbed on Ti 4+ cations react with adjacent O 2) anions (or OD groups), that in the case of TiO 2 Degussa P25 should be basic enough [13] to be able to give a nucleophilic attack to CD 3 CN forming acetamide-like species.…”

Section: Ir Studies Of Adsorbed Speciessupporting

confidence: 87%

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Comparison of Different Photocatalytic Systems for Acetonitrile Degradation in Gas–solid Regime

et al. 2005

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Photocatalytic degradation of acetonitrile was carried out in gas-solid regime by using two commercial TiO 2 samples (Merck and Degussa P25) irradiated in two continuous annular photoreactors. The inlet gas flow consisted of oxygen, nitrogen, acetonitrile and water vapours. The influence on the photodegradation rate of gas flow rate, acetonitrile, oxygen and water concentrations and photon flux was investigated. The degradation products of acetonitrile were carbon dioxide and hydrogen cyanide. The photocatalysts performance was not affected by the presence or absence of water vapour in the reacting mixture. The Langmuir-Hinshelwood model describes adequately the photoreactivity results and provides the values of kinetic and equilibrium adsorption constants. FT-IR spectroscopy was used to investigate the adsorption patterns and photo-oxidation intermediates of acetonitrile on fully hydrated surface of TiO 2 powders. Acetonitrile was adsorbed on Ti 4+ surface ions and hydroxyl groups for both types of TiO 2 . In the absence of UV light this interaction was completely reversible for Merck catalyst whereas for Degussa P25 part of adsorbed acetonitrile molecules reacted to form acetamide-like species.

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Section: Ir Studies Of Adsorbed Speciessupporting

confidence: 87%

“…Furthermore, the weaker absorptions at 2225 and 2113 cm )1 correspond to the 2m(CC) + d asym (CAC"N) combination band and to the m sym (CD 3 ) mode, respectively [11], apparently both less sensitive to the Lewis acidity of the adsorbing sites.…”

Section: Ir Studies Of Adsorbed Speciesmentioning

confidence: 93%

Comparison of Different Photocatalytic Systems for Acetonitrile Degradation in Gas–solid Regime

et al. 2005

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“…The band at 1704 cm -1 was assigned to the tilted bonded CO (CO(t)) [48], in which the C atom was bonded to a metallic Rh site, [49], and the bands assigned to the hydrogen carbonate and monodentate carbonate species appeared at ca. 1608 [50] and 1429 cm -1 [49], respectively. These carbonate species were formed by the reaction of CO with O 2-on CeO 2 .…”

Section: Ft-ir Studymentioning

confidence: 95%

The Promoting Effect of Fe Doping on Rh/CeO2 for the Ethanol Synthesis

et al. 2015

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The effects of Fe promotion were investigated on the activity and selectivity of Rh/CeO 2 catalyst for the direct synthesis of ethanol from syngas. The catalysts were comprehensively characterized by X-ray diffraction (XRD), N 2 adsorption-desorption, CO uptake, H 2 -TPR, temperature programmed surface reaction (TPSR), and FT-IR. XRD, CO uptake and FT-IR measurements indicated that Rh particles were well dispersed. TPSR results revealed that the addition of Fe changed CO dissociation behavior over the catalysts. FT-IR results showed that Fe promoter stabilized both linear carbonyl and gem-dicarbonyl species, which could be responsible for the improved catalytic activity. The interaction between Rh and Fe species is proposed to play a crucial role in achieving higher ethanol selectivity. Graphical Abstract

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“…C-H stretching bands are observed at 2932 and 2846 cm −1 for all samples and can be assigned to formate species [134,135]. The bands have similar low intensities and peak positions for the three nanoshapes.…”

Section: Figure 24mentioning

confidence: 78%

“…Clearly, these species are stable at 200 °C in He. The different types of carbonate and formate are formed as soon as CeO 2 is exposed to carbon species, such as atmospheric CO 2 [133][134][135][136][137][138]. Clearly rods and cubes have much higher integrated intensity ratios of carbonates to hydroxyl than octahedra.…”

Section: Figure 24mentioning

confidence: 99%