Raman scattering study of sodium di-n-pentyl phosphate aggregates and water content dependence of conformation about phosphorus-oxygen bonds in coagel phases

Okabayashi, Hirofumi; Taga, Keijiro; Miyagai, Kiyotaka; Uehara, Toshiyuki; Yoshida, Tadayoshi; Nishio, Etsuo

doi:10.1021/j100173a069

Cited by 15 publications

(11 citation statements)

References 6 publications

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“…Functionalization of SBA-15 with APTMS and subsequent transformation into the ammonium salt leads to the appearance of new major bands at 940 and 1040 cm -1 , respectively (spectrum (b)). They are assigned to CH 2 rocking and C-C stretch vibrations of the propylammonium group, respectively [50,51]. Spectrum (c) corresponds to deca, which shows Raman bands at 592, 826, 960 and 991 cm -1 , respectively, in good agreement with those reported for sodium decavanadate (Na 6 V 10 O 28 x 18H 2 O) [52].…”

Section: Vo X /Sba-15supporting

confidence: 77%

“…To understand the correlation between structural and catalytic properties of dispersed vanadia, various techniques including infrared [16-18a,18b], Raman [19][20][21][22][23], UV-visible [16,17,20,24,25], solid-state 51 V NMR [21], and X-ray absorption spectroscopy [18,26] have been used. In several studies, XPS has been employed to study the dispersion and oxidation state of supported vanadia catalysts [27,28].…”

Section: Introductionmentioning

confidence: 99%

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The mechanism for the controlled synthesis of highly dispersed vanadia supported on silica SBA-15

Heß

Wild

Schlögl

2006

Microporous and Mesoporous Materials

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The mechanism for the controlled synthesis of highly dispersed vanadia supported on mesoporous silica SBA-15 (VO x /SBA-15) is elucidated using X-ray photoelectron spectroscopy (XPS), Raman and diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS). The synthesis consists of functionalization of SBA-15 using 3-aminopropyltrimethoxysilane (APTMS) followed by HCl treatment, anion exchange of decavanadate (V 10 O 28 6-) and calcination to yield the final material. Spectroscopic analysis yields that APTMS is grafted onto the surface via hydroxyl groups. Under ambient conditions, protonated APTMS on SBA-15 is largely hydrolyzed and present in its bidentate and tridentate form. Detailed XPS analysis reveals a strong influence of surface water on the resulting structure of APTMS on SBA-15. Under dry conditions, the protonated APTMS molecules on SBA-15 adopt the monodentate and bidentate form. During the anion exchange reaction, decavanadate is incorporated intactly into the pores, without any changes in the structure of the organic framework. In the calcination step, decavanadate is decomposed and vanadia is anchored onto the surface of SBA-15 via silanol groups resulting in highly dispersed surface vanadia species, while the organic resiues are fully removed from the pores of the silica matrix. d

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Section: Vo X /Sba-15supporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

The mechanism for the controlled synthesis of highly dispersed vanadia supported on silica SBA-15

Heß

Wild

Schlögl

2006

Microporous and Mesoporous Materials

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“…5,12 The results proved directly that the population of an extended hydrocarbon segment increased upon aggregation. These observations are direct evidence that even simple surfactants are able to form aggregates through hydrophobic interactions among the extended short-hydrocarbon segments.…”

Section: ■ Results and Discussionmentioning

confidence: 72%

“…5,12 Depending on the water content, a specific rotational isomer about the P−O bonds was found to be stabilized preferentially.…”

Section: ■ Introductionmentioning

confidence: 99%

Aggregate Structures of Asymmetric Di-Alkyl Phosphate Anions and the Role of Conformations about the Polar Region: SANS, Cryo-TEM, Raman Scattering, ¹³C NMR, and Selective NOE Studies

et al. 2012

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The aggregate structures of two di-n-alkyl-phosphate anions (di-n-alkyl: n-butyl(n-dodecyl)(BDoP) and n-hexyl(n-dodecyl)(HDoP)) in water were studied by the use of SANS, cryo-TEM, Raman scattering, (13)C NMR, and selective NOE ((1)H{(1)H}) techniques. The results of SANS indicated that the different -CH(2)- lengths of the short chain led to a marked difference in the aggregational behavior of BDoP and HDoP. Cryo-TEM added direct images to support the average aggregation size and shape predicted by the SANS analyses. Raman scattering, (13)C NMR, and selective NOE results provided further evidence that variation of molecular conformations strongly contributed to variation in the shape of the aggregates. In particular, selective NOE was a powerful technique for investigating the dynamic structures of the hydrocarbon chains during growth of the micelles.

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“…First, the low-frequency region of the spectra will be discussed (Figure 1 A). [48,49] Ammonium heptamolybdate (AHM) was used as the molybdenum oxide precursor in the ion exchange step. The intense band is attributed to cyclic tetrasiloxane rings (D1 defect mode).…”

Section: X-ray Photoelectron Spectroscopy (Xps)mentioning

confidence: 99%

Controlled Synthesis and Characterization of Highly Dispersed Molybdenum Oxide Supported on Silica SBA‐15

Thielemann¹,

Weinberg²,

Heß³

2011

ChemCatChem

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Silica-supported molybdenum oxide catalysts with high densities of disperse molybdenum oxide species of up to 3.5 atoms nm−2 were prepared by using a novel synthesis approach on the basis of functionalized mesoporous SBA-15. As revealed by using Raman spectroscopy and thermal analysis, the synthesis mechanism consists of an ion exchange of heptamolybdate ions (Mo7O246−) into the porous functionalized framework and decomposition of the intact precursor into smaller fragments during final calcination. The amount of dispersed molybdenum oxide as well as the ratio of dispersed to crystalline molybdenum oxide was determined in detail for Mo densities of 0–13.0 atoms nm−2 by using a combination of X-ray fluorescence (XRF), energy-dispersive X-ray analysis (EDX), and Raman spectroscopy. Up to 3.5 atoms nm−2 dehydrated molybdenum oxide is present exclusively as dispersed species. At higher densities, additional Mo is introduced as crystalline MoO3, and the amount of dispersed species remains unchanged. The structure of the supported molybdenum oxide under ambient conditions largely resembles that of heptamolybdate ions. Dehydration leads to the formation of grafted monomeric and connected molybdenum oxide surface species. Detailed X-ray photoelectron spectroscopy (XPS) analysis revealed an increase in the Mo/Si ratio as well as a positive binding energy shift upon dehydration, indicative of an increase in the dispersion of the supported molybdenum oxide. The combination of Raman and XPS analyses establishes a correlation of the changes in structure and dispersion of the supported molybdenum oxide species

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Raman scattering study of sodium di-n-pentyl phosphate aggregates and water content dependence of conformation about phosphorus-oxygen bonds in coagel phases

Cited by 15 publications

References 6 publications

The mechanism for the controlled synthesis of highly dispersed vanadia supported on silica SBA-15

The mechanism for the controlled synthesis of highly dispersed vanadia supported on silica SBA-15

Aggregate Structures of Asymmetric Di-Alkyl Phosphate Anions and the Role of Conformations about the Polar Region: SANS, Cryo-TEM, Raman Scattering, ¹³C NMR, and Selective NOE Studies

Controlled Synthesis and Characterization of Highly Dispersed Molybdenum Oxide Supported on Silica SBA‐15

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Raman scattering study of sodium di-n-pentyl phosphate aggregates and water content dependence of conformation about phosphorus-oxygen bonds in coagel phases

Cited by 15 publications

References 6 publications

The mechanism for the controlled synthesis of highly dispersed vanadia supported on silica SBA-15

The mechanism for the controlled synthesis of highly dispersed vanadia supported on silica SBA-15

Aggregate Structures of Asymmetric Di-Alkyl Phosphate Anions and the Role of Conformations about the Polar Region: SANS, Cryo-TEM, Raman Scattering, 13C NMR, and Selective NOE Studies

Controlled Synthesis and Characterization of Highly Dispersed Molybdenum Oxide Supported on Silica SBA‐15

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Product

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Aggregate Structures of Asymmetric Di-Alkyl Phosphate Anions and the Role of Conformations about the Polar Region: SANS, Cryo-TEM, Raman Scattering, ¹³C NMR, and Selective NOE Studies