Influence of the Preparation and of the Activation Treatments on the Catalytic Activity of Mechanical Mixtures of Sulfated Zirconia and Pt/Al2O3

Tichit, Didier; Alami, D. El; Figuéras, F.

doi:10.1006/jcat.1996.0301

Cited by 24 publications

(10 citation statements)

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“…In the sulfated sample, the dehydroxylation proceeded between 250 and 450 °C, and crystallite size did not change, suggesting that SO 4 species remain bonded at the surface; then, the total weight loss (3.084 wt %) must be associated with the dehydroxylation process and it was lower (Figure ) than that observed on the non-sulfated SnO 2 (6.27 wt %) . The difference in the hydroxyl content could be associated with the ion exchange of OH groups by HSO 4 - assuming that the sulfating process is carried out by the following reaction: , …”

Section: Resultsmentioning

confidence: 89%

Effects of the SO₄Groups on the Textural Properties and Local Order Deformation of SnO₂Rutile Structure

Toledo-Antonio

et al. 2004

Langmuir

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Sulfated tin oxide was synthesized from a hydroxylated tin oxide obtained by the precipitation method, followed by ion exchange of OH groups by SO4 species with a sulfuric acid solution. The samples were characterized by X-ray diffraction, transmission electron microscopy, thermoanalysis, and nitrogen physisorption by the Brunauer-Emmett-Teller method. The rutile crystalline structure was refined by the Rietveld method. Thermal analysis suggests the following stoichiometric formulas: SnO2-x(OH)2x and SnO2-x(OH)x(HSO4)x with X = 0.35 and 0.17 for non-sulfated and sulfated samples, respectively. The SO4 species remained strongly bonded at the SnO2 surface stabilizing its crystallite size against sintering, inhibiting the crystallite aggregation, and it acts as a structure porogen director mediating nanoparticle growth and assembly yielding a mesostructure form of SnO2 with wormhole morphology and high thermal stability. The interaction between SO4(2-) and the SnO2 surface changes the symmetry of the representative tin-oxygen octahedron. It relaxes the four tin-oxygen bond lengths located at the basal plane of the octahedron while the two apical Sn-O bonds decrease, producing a strong deformed octahedron, which could be transformed into a higher asymmetry in the electronic distribution around the Sn4+ nuclei. The elimination of SO4 groups brings about the coalescence and crystallite growth, which collapse the mesostructure form of SnO2, decreasing the surface area and porosity.

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Section: Resultsmentioning

confidence: 89%

Effects of the SO₄Groups on the Textural Properties and Local Order Deformation of SnO₂Rutile Structure

Toledo-Antonio

et al. 2004

Langmuir

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“…exhibiting an acidity stronger than that of 100% sulfuric acid. [11][12][13][14] However, this point of view has been contradicted by many groups. [15][16][17][18][19] The noncorrosive acid SZ exhibits a high activity for low-temperature n-butane isomerisation.…”

Section: Introductionmentioning

confidence: 99%

Freeze-dried promoted and unpromoted sulfated zirconia and their catalytic potential

et al. 2001

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A new synthesis route for sulfated zirconia and iron, manganese, and iron-manganese promoted sulfated zirconia has been investigated. Zirconium hydroxide precursors were prepared from hydrogel and hydroalcogel; freeze-drying as well as oven-drying has been employed. The pure hydroxides, sulfated, and metal promoted sulfated zirconia were calcined at 650 uC and characterised by chemical analysis, XRD, TG/DTG/ DTA, nitrogen adsorption, SEM, FTIR pyridine adsorption, and ammonia TPD. The catalytic activity of the samples was screened in the double bond isomerisation of 1-butene and the benzoylation of anisole.Significant differences in the textural and acidic properties were found for samples prepared either by freezeor oven-drying. Virtually no difference in acidity was observed between sulfated and metal promoted sulfated zirconia.Freeze-drying, especially the hydro-alcogel synthesis, was found to be a powerful preparation method for promoted and unpromoted sulfated zirconia catalysts.

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“…Moreover, some reports pointed that only part of sulfur species on the catalyst may contribute to the isomerization activity (Li et al, 2004;Manoilova et al, 2007). Although the catalyst acidity could not be neglected for the isomerization activity, according to a bifunctional isomerization mechanism (Tichit et al, 1996), the recent investigation showed that the acidity of catalyst and the redox cycles in the reaction synergistically played a role in the determining the isomerization activity (González et al, 1997;Moreno and Poncelet, 2001). Thus, it was not surprising that the acidity of the catalyst could not be well correlated with the isomerization activity.…”

Section: Discussionmentioning

confidence: 98%

Normal Hexane Hydroisomerization Over an Alumina and Yttria Promoted Pt/SO₄²⁻/ZrO₂Catalyst

Zhou

Song

Zhang

et al. 2013

Petroleum Science and Technology

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Sulfated zirconia was promoted with alumina and yttria in order to improve catalyst isomerization behaviors. The n-hexane hydroisomerization reaction was carried out in a continuous flow fixed-bed reactor for 80 h on stream to evaluate catalyst reaction stability. The catalyst was characterized by XRD, TGA, H 2 -TPR, and NH 3 -TPD technologies in order to investigate the crystalline structure, sulfur content, reduction behavior, and acidity of the catalyst. It was proved that the addition of alumina and yttria obviously increased the sulfur content on the fresh catalyst and also markedly stabilized the sulfur species on the used catalysts. Thus, the modified catalyst possessed the better stable activity and selectivity although the addition of promoter could not enhance the isomerization activity. The crystalline structure of sulfated zirconia, acidity, and sulfur content only showed a limited influence on the isomerization activity of the catalyst. This work would have potential use to prepare an ideal catalyst for a commercial alkane hydroisomerization unit.

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Influence of the Preparation and of the Activation Treatments on the Catalytic Activity of Mechanical Mixtures of Sulfated Zirconia and Pt/Al2O3

Cited by 24 publications

References 0 publications

Effects of the SO₄Groups on the Textural Properties and Local Order Deformation of SnO₂Rutile Structure

Effects of the SO₄Groups on the Textural Properties and Local Order Deformation of SnO₂Rutile Structure

Freeze-dried promoted and unpromoted sulfated zirconia and their catalytic potential

Normal Hexane Hydroisomerization Over an Alumina and Yttria Promoted Pt/SO₄²⁻/ZrO₂Catalyst

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Influence of the Preparation and of the Activation Treatments on the Catalytic Activity of Mechanical Mixtures of Sulfated Zirconia and Pt/Al2O3

Cited by 24 publications

References 0 publications

Effects of the SO4Groups on the Textural Properties and Local Order Deformation of SnO2Rutile Structure

Effects of the SO4Groups on the Textural Properties and Local Order Deformation of SnO2Rutile Structure

Freeze-dried promoted and unpromoted sulfated zirconia and their catalytic potential

Normal Hexane Hydroisomerization Over an Alumina and Yttria Promoted Pt/SO42−/ZrO2Catalyst

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Effects of the SO₄Groups on the Textural Properties and Local Order Deformation of SnO₂Rutile Structure

Effects of the SO₄Groups on the Textural Properties and Local Order Deformation of SnO₂Rutile Structure

Normal Hexane Hydroisomerization Over an Alumina and Yttria Promoted Pt/SO₄²⁻/ZrO₂Catalyst