A vibrational spectral study of hydrated tantalum phosphate(TaPO5) phases

Stranford, G.T.; Condrate, R. A.

doi:10.1016/s0022-4596(05)80091-x

Cited by 4 publications

(4 citation statements)

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“…26 The band observed between 200 and 400 cm À1 can be assigned to O-Ta-O bending modes for the Ta 2 O 5 -300 sample and to various O-P-O and O-Ta-O bending modes for TaOPO 4 -m samples. 34 Furthermore, with increasing m, the area ratio of the peak assigned to P-O to the peak assigned to Ta-O increased.…”

Section: Physicochemical Propertiesmentioning

confidence: 96%

Mesoporous tantalum phosphates: preparation, acidity and catalytic performance for xylose dehydration to produce furfural

et al. 2016

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Mesoporous tantalum phosphates (TaOPO 4 -m) with varying P/Ta molar ratios (m ¼ 0.41-0.89) were prepared, comprehensively characterized by ICP-AES, N 2 physisorption, small-angle XRD, TEM, Raman, FT-IR, NH 3 -TPD and IR of pyridine adsorption and employed to catalyze the dehydration of xylose to produce furfural in a biphasic batch reactor. The physicochemical properties of these TaOPO 4 -m samples were affected significantly by variation of m. More ordered mesopores were formed in the sample with a higher m. On the other hand, the density of acidity decreased but the ratio of Brønsted acidity to Lewis acidity (B/L) increased with the increase in m. TaOPO 4 -0.84, which showed adequate mesoporosity and a high B/L ratio, was identified as the best performing catalyst among these TaOPO 4m catalysts in terms of high furfural selectivity (ca. 72 mol%). Correlating the catalyst performance with its acid property showed that the xylose consumption rate decreased with the increasing B/L ratio, while furfural selectivity showed a volcano-type dependence on the B/L ratio. Besides, the huge decrease in the furfural selectivity after poisoning the Brønsted acid sites by adding 2,6-dimethyl pyridine revealed a kind of Brønsted acid catalysis for selective furfural production. Fig. 7 Performance of the TaOPO 4 -m catalysts with different molar P/Ta ratio m by the time courses of (A) xylose conversion, (B) furfural selectivity: m ¼ 0.41 (-), m ¼ 0.61 (B), m ¼ 0.75 (:), m ¼ 0.84 (A), and m ¼ 0.89 (P).This journal is

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Section: Physicochemical Propertiesmentioning

confidence: 96%

Mesoporous tantalum phosphates: preparation, acidity and catalytic performance for xylose dehydration to produce furfural

et al. 2016

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“…13) and TaPO 5 samples tends to show adsorbed water only. Stranford confirmed the existence of a H-O-H band located at 1625 cm −1 for hydrated TaPO 5 heated at 300 • C [24]. The elimination of that band on nitridophosphate sample is effective when the temperature reaches 100 • C. A characteristic of TaPO 5−x N 2x/3 samples is the presence, at the lowest nitrogen content, of a band at 1550 cm −1 attributed to the symmetric bending vibrational frequency of -NH 2 groups linked to phosphorus atoms (-PNH 2 ).…”

Section: Oxynitridesmentioning

confidence: 88%

“…% H 2 O uptake). The dehydration of TaPO 5 ·xH 2 O is mainly complete over 600 • C with the complete formation of crystalline ␤-TaPO 5 occurring at 900 • C [24].…”

Section: Oxide Precursorsmentioning

confidence: 99%

“…The broadness of the band at 1280 cm −1 and the shoulder at 1170 cm −1 indicate that PO 4 units are highly distorted from tetrahedral symmetry in the amorphous powders. Such distortion could be due to protonated PO 4 in the structure [24]. These bands are broadening when the nitrogen content is increasing due to a growing contribution of P N stretching modes from -N P-N groups overlaping with the P O and P-O 2 bands.…”

Section: Oxynitridesmentioning

confidence: 99%

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