Acidity Of Montmorillonite-(Ce or Zr) Phosphate Cross-Linked Compounds

Rey-Bueno, F. Del; Garcı́a-Rodrı́guez, A.; Mata-Arjona, A.; Rey-Perez-Caballero, F.J. del

doi:10.1346/ccmn.1995.0430505

Cited by 7 publications

(5 citation statements)

References 27 publications

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“…The Brønsted and Lewis acidity of clays have also been studied. − Lewis acidity within the clays arises from incompletely coordinated Al sites. Brønsted acidity arises when the cations are replaced with hydrogen ion by treatment of clay with sulfuric acid or when the exchangeable cations become hydrated.…”

Section: Introductionmentioning

confidence: 99%

Intrazeolite Photochemistry. 22. Acid−Base Properties of Coumarin 6. Characterization in Solution, the Solid State, and Incorporated into Supramolecular Systems

et al. 1998

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The spectroscopic properties of the dye coumarin 6 in solution are reported. Relatively large shifts are seen in both the absorption and fluorescence spectra upon protonation. The very large Stokes shift that is seen for the dye in its solid state and as the hydrochloride salt reveals that the dye molecules are forming aggregates, which is a phenomenon that is also seen in very high concentrations of coumarin 6 in solution. The acidbase properties of coumarin 6 in heterogeneous systems such as zeolites and clays are also presented. We have found that this dye molecule is extremely sensitive to the presence of Lewis and Brønsted sites and were able to detect acidity in the faujasite zeolite NaY which is usually considered to be nonacidic. Two series of faujasite zeolites, one in which the Brønsted acidity increases and the other in which the Lewis acidity increases, were also studied. The dication of the dye was detected in both HY100 and CBV 740, the zeolites with the highest Brønsted and highest Lewis acidity, respectively, used in the present study. Due to the large shifts seen for coumarin 6 in its neutral, monocation, and dication forms, both the absorption and fluorescence spectra resulted in detection of two species of the dye in those zeolites with intermediate acidity.The ability of coumarin 6 to sense small amounts of Lewis and Brønsted sites makes it an attractive molecule to study other systems as well.

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Section: Introductionmentioning

confidence: 99%

Intrazeolite Photochemistry. 22. Acid−Base Properties of Coumarin 6. Characterization in Solution, the Solid State, and Incorporated into Supramolecular Systems

et al. 1998

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“…In addition, the symmetric bending band at 1396 cm −1 indicates ammonia in the form of a conjugate acid based on interactions with hydrogen from Brønsted sites. 35,36 …”

Section: Resultsmentioning

confidence: 99%

“…The catalyst acidities were estimated based on the gravimetric method, using the amounts of ammonia vapor absorbed by the catalysts which were rst placed under vacuum conditions. 35,36 A vacuum was applied to prevent any interference by water vapor that might have been adsorbed by the catalyst. The acidities of the nano ZrO 2 , nano ZrO 2 -SO 4 and Pt/nano ZrO 2 -SO 4 are summarized in Table 2, and these data demonstrate that the nano ZrO 2 had low total acidity, resulting from Zr 4+ species acting as Lewis acid sites.…”

Section: Catalyst Acidity Analysismentioning

confidence: 99%

“…In addition, the symmetric bending band at 1396 cm À1 indicates ammonia in the form of a conjugate acid based on interactions with hydrogen from Brønsted sites. 35,36 3.5 XRD characterization The ZrO 2 typically used as a catalyst has only three crystal phases (tetragonal, monoclinic and metastable tetragonal), 37 and the characteristic peaks at 2q ¼ 28.3 (À111) and 31.6 (111) correspond to the monoclinic crystal phase. 13 In general, this series of diffraction patterns indicates stable crystallinity, although the addition of sulphate modied the crystal phase of the nano ZrO 2 .…”

Section: Catalyst Acidity Analysismentioning

confidence: 99%

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Hydrothermal preparation of a platinum-loaded sulphated nanozirconia catalyst for the effective conversion of waste low density polyethylene into gasoline-range hydrocarbons

et al. 2019

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A platinum-loaded sulphated nanozirconia (Pt/nano ZrO 2 -SO 4 ) bifunctional metal-acid catalyst was synthesized using a hydrothermal process. The nano ZrO 2 -SO 4 was initially prepared by dispersing the nano ZrO 2 in H 2 SO 4 , followed by wet impregnation via heating in an aqueous PtCl 4 solution. This material was subsequently calcined and reduced under hydrogen gas to produce the catalyst. The Pt/ nano ZrO 2 -SO 4 was found to be a highly active, selective and stable solid acid catalyst for the conversion of waste low density polyethylene (LDPE) to high value hydrocarbons. The catalytic activity and stability of this material were evaluated during the hydrocracking of waste LDPE while optimizing the reaction temperature, time and catalyst-to-feed ratio. The activity of catalyst prepared by hydrothermal was attributed to highly dispersion of Pt species interacting with the support and inhibition of the agglomeration process. The impregnation method of hydrothermal generated highly active and selective catalyst with Pt loads of 1 wt%. The hydrocracking of waste LDPE over Pt/nanoZrO 2 -SO 4 at 250 C for 60 min with a catalyst-to-feed proportion of 1 wt% gave the largest gasoline fraction.

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“…Shows the FT-IR spectra of adsorbed ammonia. Ammonia adsorbed over the samples on Brønsted acid sites forms ammonium ion with vibration bands at 1404 cm -1 while the coordination bond of ammonia on Lewis acid sites yields characteristic bands at 1119 cm -1 [21,22]. At higher sulfuric acid concentration of SZ calcined at 600 °C, the amount of Brønsted and Lewis acid sites is increased.…”

mentioning

confidence: 98%

Effect of Sulfuric Acid Treatment and Calcination on Commercial Zirconia Nanopowder

Utami

Wijaya

Trisunaryanti

2017

KEM

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The modification of commercial zirconia nanopowder by sulfuric acid and heat treatment was conducted. The aim of this present research was to obtain a stable modified zirconia nanopowder chemically and thermally by studying the effect of sulfuric acid treatment and calcination temperature on commercial zirconia nanopowder. The material was prepared by dispersing the commercial zirconia nanopowder into 0.2, 0.5 and 0.8 M sulfuric acid solutions, followed by calcination at varied temperatures, i.e. 600, 700, 800 and 900 °C. The so called sulfated zirconias then were characterized their physicochemical properties using FT-IR, XRD and SEM-EDX analysis methods. The optimized condition for that modification was obtained by using sulfuric acid of 0.8 M and calcination temperature of 600 °C. The characterization results also revealed that using ammonia adsorption method, the acidity of the catalyst was found to be 1.06 mmol/g.

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Acidity Of Montmorillonite-(Ce or Zr) Phosphate Cross-Linked Compounds

Cited by 7 publications

References 27 publications

Intrazeolite Photochemistry. 22. Acid−Base Properties of Coumarin 6. Characterization in Solution, the Solid State, and Incorporated into Supramolecular Systems

Intrazeolite Photochemistry. 22. Acid−Base Properties of Coumarin 6. Characterization in Solution, the Solid State, and Incorporated into Supramolecular Systems

Hydrothermal preparation of a platinum-loaded sulphated nanozirconia catalyst for the effective conversion of waste low density polyethylene into gasoline-range hydrocarbons

Effect of Sulfuric Acid Treatment and Calcination on Commercial Zirconia Nanopowder

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