A study on the preparation of supported metal oxide catalysts using JRC-reference catalysts. I. Preparation of a molybdena–alumina catalyst. Part 1. Surface area of alumina

Okamoto, Yasuaki; Arima, Yusaku; Nakai, Kenta; Umeno, Satoshi; Katada, Naonobu; Yoshida, Hisao; Tanaka, Tsunehiro; Yamada, Masahito; Akai, Yoshio; Segawa, Kohichi; Nishijima, Akio; Matsumoto, Hideyuki; Niwa, Miki; Uchijima, Toshio

doi:10.1016/s0926-860x(98)00064-7

Cited by 42 publications

(26 citation statements)

References 31 publications

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“…Our calculations indicate that only H x P 2 Mo 5 O 23 (6-x)-complexes will be formed in acidic solutions at Mo/P ratios of 2:1 and 1:1. The H x P 2 Mo 5 O 23 (6-x)-complex is stable in different protonation states over a wide pH range. Characteristic Raman peaks in the corresponding Raman spectra (Figure 1) can be found at 370 and 395 cm -1 (δ(MoO 2t )).…”

Section: Raman Spectroscopy On Reference Solutions a Momentioning

confidence: 76%

“…Characteristic Raman peaks in the corresponding Raman spectra (Figure 1) can be found at 370 and 395 cm -1 (δ(MoO 2t )). At pH 2.0 the ν s (MoO 2t ) and ν as (MoO 2t ) vibrations of the H x P 2 Mo 5 O 23 (6-x)-complex are found at 942 cm -1 and 893 cm -1 , respectively. These bands shift to lower frequency upon deprotonation.…”

Section: Raman Spectroscopy On Reference Solutions a Momentioning

confidence: 94%

“…At 30 min after impregnation, ν(MoO 2t ) peaks at 956, 928, and 878 cm -1 are observed near the edge of the pellets. The δ(MoO 2t ) vibrations at 370 and 395 cm -1 that are observed reveal that Mo is present as a H x P 2 Mo 5 O 23 (6-x)-heteropolyanion (Table 2). At the same time, hardly any Mo complexes are observed near the core of the catalyst bodies.…”

Section: Raman Spectroscopy On Reference Solutions a Momentioning

confidence: 96%

“…At the same time, hardly any Mo complexes are observed near the core of the catalyst bodies. At 90 min after impregnation, δ(MoO 2t ) vibrations at 370 and 395 cm -1 are observed over the entire profile, indicating the presence of H x P 2 Mo 5 O 23 (6-x)-throughout the support bodies ( Table 2). The main ν(MoO 2t ) vibration is observed at 929 cm -1 for all positions inside the alumina support.…”

Section: Raman Spectroscopy On Reference Solutions a Momentioning

confidence: 99%

“…These bands shift to lower frequency upon deprotonation. The P 2 Mo 5 O 23 6-complex, present in solution at pH 6, shows bands at 956, 926, and 874 cm -1 . In basic solutions, all Mo will again be present as MoO 4 2-, as the equilibrium shifts to the left according to eq 4.…”

Section: Raman Spectroscopy On Reference Solutions a Momentioning

confidence: 99%

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Envisaging the Physicochemical Processes during the Preparation of Supported Catalysts: Raman Microscopy on the Impregnation of Mo onto Al₂O₃ Extrudates

et al. 2004

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Raman microscopy has been applied to study the preparation of shaped Mo/Al2O3 catalysts. The speciation of different Mo complexes over γ-Al2O3 support bodies was followed in time after pore volume impregnation with aqueous solutions containing different Mo complexes. The addition of NO3 -to the impregnation solutions allows for a quantitative Raman analysis of the distribution of different complexes over the catalyst bodies as this ion can be used as an internal standard. After impregnation with an acidic ammonium heptamolybdate (AHM) solution, the strong interaction between Mo7O24 6-and Al2O3 results in slow transport of this complex through the support and extensive formation of Al(OH)6Mo6O18 3-near the outer surface of the support bodies. This may be prevented by decreasing the interaction between Mo and Al2O3. In this way, transport is facilitated and a homogeneous distribution of Mo is obtained on a reasonable time scale. A decrease in interaction between Mo and Al2O3 can be achieved by using alkaline impregnation solutions or by the addition of complexing agents, such as citrate and phosphate, to the impregnation solution. In general, time-resolved in situ Raman microscopy can be a valuable tool to study the physicochemical processes during the preparation of supported catalysts.

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Section: Raman Spectroscopy On Reference Solutions a Momentioning

confidence: 76%

Section: Raman Spectroscopy On Reference Solutions a Momentioning

confidence: 94%

Section: Raman Spectroscopy On Reference Solutions a Momentioning

confidence: 96%

Section: Raman Spectroscopy On Reference Solutions a Momentioning

confidence: 99%

Section: Raman Spectroscopy On Reference Solutions a Momentioning

confidence: 99%

See 3 more Smart Citations

Envisaging the Physicochemical Processes during the Preparation of Supported Catalysts: Raman Microscopy on the Impregnation of Mo onto Al₂O₃ Extrudates

et al. 2004

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Characterization of SiO₂ Deposited by CVD on Mo_xO_y/Al₂O₃ using NMR and TOF‐SIMS

Boateng¹,

Hill²

2008

Chemical Vapor Deposition

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Silica (SiO 2 ) is deposited onto the surface of Mo x O y /Al 2 O 3 using CVD in a fluidized bed. The resulting deposit is characterized using N 2 physisorption, inductively coupled plasma (ICP) spectrometry, 29 Si nuclear magnetic resonance (NMR) and time of flight-secondary ion mass spectrometry (TOF-SIMS). The ICP and physisorption results show that the amount deposited on the surface reaches a plateau value after 30-60 min. Based on the NMR and TOF-SIMS analysis, this plateau value corresponds to 2-3 monolayers. The surface coverage is not uniform, and the presence of Mo on the exterior surface of Al 2 O 3 hinders the deposition of silica.

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Association of Molybdenum Ionic Species with Alumina Surface

Shafei

Moussa

Philip

2000

Journal of Colloid and Interface Science

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A study on the preparation of supported metal oxide catalysts using JRC-reference catalysts. I. Preparation of a molybdena–alumina catalyst. Part 1. Surface area of alumina

Cited by 42 publications

References 31 publications

Envisaging the Physicochemical Processes during the Preparation of Supported Catalysts: Raman Microscopy on the Impregnation of Mo onto Al₂O₃ Extrudates

Envisaging the Physicochemical Processes during the Preparation of Supported Catalysts: Raman Microscopy on the Impregnation of Mo onto Al₂O₃ Extrudates

Characterization of SiO₂ Deposited by CVD on Mo_xO_y/Al₂O₃ using NMR and TOF‐SIMS

Association of Molybdenum Ionic Species with Alumina Surface

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A study on the preparation of supported metal oxide catalysts using JRC-reference catalysts. I. Preparation of a molybdena–alumina catalyst. Part 1. Surface area of alumina

Cited by 42 publications

References 31 publications

Envisaging the Physicochemical Processes during the Preparation of Supported Catalysts: Raman Microscopy on the Impregnation of Mo onto Al2O3 Extrudates

Envisaging the Physicochemical Processes during the Preparation of Supported Catalysts: Raman Microscopy on the Impregnation of Mo onto Al2O3 Extrudates

Characterization of SiO2 Deposited by CVD on MoxOy/Al2O3 using NMR and TOF‐SIMS

Association of Molybdenum Ionic Species with Alumina Surface

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Product

Resources

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Envisaging the Physicochemical Processes during the Preparation of Supported Catalysts: Raman Microscopy on the Impregnation of Mo onto Al₂O₃ Extrudates

Envisaging the Physicochemical Processes during the Preparation of Supported Catalysts: Raman Microscopy on the Impregnation of Mo onto Al₂O₃ Extrudates

Characterization of SiO₂ Deposited by CVD on Mo_xO_y/Al₂O₃ using NMR and TOF‐SIMS