Surface structures of supported molybdenum oxide catalysts under ambient conditions

Kim, Du Soung; Segawa, Kohichi; Soeya, Tomotsune; Wachs, Israel E.

doi:10.1016/0021-9517(92)90084-u

Cited by 128 publications

(72 citation statements)

References 43 publications

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“…Whatever the position explored, similar Raman spectra have been obtained: an intense asymmetric band, centered at 942 cm −1 , with a strong shoulder at lower frequency. This shape is standard for dried catalysts [16,17] and can be assigned to P 2 (main band at 941 cm −1 in aqueous solution), or to a mixture of these two species [7]. For calcination temperatures between +30 and +280…”

Section: Comop/al 2 O 3 Catalystsmentioning

confidence: 95%

Monitoring Hydrotreating Catalysts Synthesis and Deactivation using Raman Spectrometry

Digne¹,

Marchand²,

Bourges³

2007

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Suivi de la synthèse et de la désactivation des catalyseurs d'hydrotraitement par spectrométrie Raman -La spectrométrie Raman est devenue une technique de caractérisation populaire pour les catalyseurs d'hydrotraitement : elle fournit des informations importantes sur la structure chimique, au cours du cycle de synthèse du catalyseur. Les phénomènes physico-chimiques se déroulant sur la surface du catalyseur peuvent être suivis par cette technique. Cet article décrit quelques exemples où la spectrométrie Raman a permis d'évaluer l'impact de paramètres expérimentaux (choix de précur-seurs métalliques, présence d'impureté, influence de la température de calcination, dépôt de coke) sur la structure du catalyseur. Abstract -Monitoring Hydrotreating Catalysts Synthesis and Deactivation using Raman Spectrometry -Raman spectrometry has become a popular characterization technique for hydrotreatment catalysts: it provides important information on chemical structures along all the synthesis cycle

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Section: Comop/al 2 O 3 Catalystsmentioning

confidence: 95%

Monitoring Hydrotreating Catalysts Synthesis and Deactivation using Raman Spectrometry

Digne¹,

Marchand²,

Bourges³

2007

Oil & Gas Science and Technology - Rev. IFP

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“…3 and 4, respectively. In the case of the M-O.OO-Mo sample two weak bands at 880 and 955 em -1 have been observed, in addition to the characteristic bands of crystalline Mo0 3 • These two weak bands according to bibliography can be attributed to molybdena interaction species (M070~4 and/or M080~6) [18,19,21,22]. The negative feature which appears in the figure beyond 1000 em -1 is due to the high sensitivity of the spectrometer.…”

Section: Qualitative Analysis Of N0mentioning

confidence: 81%

“…Doping of the support by Be 2 + cations has led to a weakening of the above mentioned bands. Doping by Mg 2 + has resulted in the disappearance of the bands attributed to crystalline Mo0 3 and the appearance of bands which characterize surface polymolybdates and molybdate species well interacted with MgO [19,22]. The Raman bands at 968, 956, 912, 855, 370, 348 and 276 em -1 are evidence for the existence of crystalline MgMo0 4 [22].…”

Section: Qualitative Analysis Of N0mentioning

confidence: 87%

“…These must be considered as: (a) the anti symmetric stretching mode of Mo-OMo bridges as far as the peak at 880 cm -1 is concerned and (b) the Mo =°stretching mode giving the peak at 955cm-1 [18,21,22]. The weakening of the Raman bands attributed to crystalline MoO) with the addition of Be 2 + can be attributed to the formation of better dispersed MO(VI) surface species.…”

Section: Discussionmentioning

confidence: 97%

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Characterization of Mo Species Supported on SiO₂ Modified with Be²⁺ and Mg²⁺

Aroni

1997

Ber Bunsenges Phys Chem

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Tho series of modified carriers (m.c.) have been prepared by doping silica with various amounts of Be 2 + and Mg 2 + . The prepared m.c. have been used as supports for the preparation of supported MO(VI) oxide catalysts. The magnitude of interactions between Si0 2 and Be 2 + or Mg 2 + nitrates depends on the kind and content of the cation. After calcination at 600°C a greater fraction of cations remains on the support surface as well dispersed M(NO~t in the case of Mg 2 + m.c. Concerning the Mo containing samples it was found that doping by Be 2 + and Mg + causes a solid state transformation of octahedral MO(VI) to tetrahedral MO(VI). As before, the extent of the effect differs between Be 2 + and Mg 2 + and it varies with the content of cation. This effect has been attributed to the inhibition of the polymerization of monomeric Mo(VI) species and/or to the formation of molybdate salts.

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“…The great flexibility of supported molybdenum catalysts is related to the different molecular structures that molybdenum species can thereby simultaneously possess, and to the ability of the Mo atoms to form various oxidation states, depending on the pre-treatment and the reaction [22]. Kim et al [26] extensively studied the molar structures and reactivity of supported Mo oxides. Mo oxide catalysts can be used for the partial oxidation of toluene.…”

Section: Introductionmentioning

confidence: 99%

Hydroconversion of acetic acid over carbon aerogel supported molybdenum catalyst

Abraham

Nagy

Dobos

et al. 2014

Microporous and Mesoporous Materials

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High surface area carbon aerogels with increasing molybdenum content were obtained by carbonization of resorcinol-formaldehyde polymer aerogels after incipient wetness impregnation (IWI). The Mo(VI) form of the impregnant was converted into different molybdenum species during the heat treatment, resulting in samples with substantially different surface and bulk compositions. The samples were tested in the hydroconversion reaction of acetic acid, a model biomass. The reaction pathways and the product distribution were governed by the accessibility of the carbon surface as well as by the amount and form of Mo. The highest selectivity for ethanol was 16 %, when 85 % of the acetic acid was converted. Post-catalyst analysis of the aerogels revealed that their morphology and chemistry changed substantially during the redox processes.The products of each of the three potential pathways (hydrogenolysis, ketonization and consecutive reduction) oxidized the surface even in the reductive hydrogen flow.

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Surface structures of supported molybdenum oxide catalysts under ambient conditions

Cited by 128 publications

References 43 publications

Monitoring Hydrotreating Catalysts Synthesis and Deactivation using Raman Spectrometry

Monitoring Hydrotreating Catalysts Synthesis and Deactivation using Raman Spectrometry

Characterization of Mo Species Supported on SiO₂ Modified with Be²⁺ and Mg²⁺

Hydroconversion of acetic acid over carbon aerogel supported molybdenum catalyst

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Surface structures of supported molybdenum oxide catalysts under ambient conditions

Cited by 128 publications

References 43 publications

Monitoring Hydrotreating Catalysts Synthesis and Deactivation using Raman Spectrometry

Monitoring Hydrotreating Catalysts Synthesis and Deactivation using Raman Spectrometry

Characterization of Mo Species Supported on SiO2 Modified with Be2+ and Mg2+

Hydroconversion of acetic acid over carbon aerogel supported molybdenum catalyst

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Characterization of Mo Species Supported on SiO₂ Modified with Be²⁺ and Mg²⁺