Comparaison des propriétés catalytiques de quelques oxydes sulfatés

Babou, F.; Coudurier, G.; Vedrine, J. C.

doi:10.1051/jcp/1995921457

Cited by 6 publications

(8 citation statements)

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“…The nature of the sulfate species was investigated by IR spectroscopy, with focus on the species absorbing at 1385-1405 cm -1 , which were assigned to adsorbed SO 3 [29,91] or disulfate species [29], and were proposed to represent active species [57]. The overtone of this band, located at 2755-2770 cm -1 is more suitable for quantitative analysis than the fundamental; it is largely isolated from other bands and the reflectance is high (ρ>0.7) so that it can be assumed that the Kubelka-Munk function should be proportional to the concentration of absorbing species.…”

Section: Stability Of Phase and Of Sulfate During Mechanochemical Trementioning

confidence: 99%

The Balance Between Reactivity and Stability of Modified Oxide Surfaces Illustrated by the Behavior of Sulfated Zirconia Catalysts

Klose-Schubert

Jentoft

2011

Top Catal

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The stability of a series of sulfated zirconia catalysts, promoted with up to 2 wt% iron or manganese, in their calcined state was investigated. Phase composition, nature of surface sulfate species, degree of hydroxylation, and butane isomerization activity changed duri ng aging over months in various atmospheres and during milling. The metastability of small oxide particles is discussed, including literature data on alumina, titania and other oxides. Catalytically active fractions of a material easily transition into more stable, less active forms.

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Section: Stability Of Phase and Of Sulfate During Mechanochemical Trementioning

confidence: 99%

The Balance Between Reactivity and Stability of Modified Oxide Surfaces Illustrated by the Behavior of Sulfated Zirconia Catalysts

Klose-Schubert

Jentoft

2011

Top Catal

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“…The Brønsted-to-Lewis sites ratio increases with increasing sulfate content. Unfortunately, the correctness of the number of Lewis sites as obtained by pyridine adsorption was questioned, because this strong nucleophile may substitute sulfate as a ligand of Zr ions and the Lewis acid sites will be over-determined [43]. Correlations of the reaction rate to the total number of acid sites as measured by ammonia adsorption are not always convincing, e.g.…”

Section: Structure-activity Relationshipsmentioning

confidence: 99%

Oxo‐Anion Modified Oxides

Jentoft

2008

Handbook of Heterogeneous Catalysis

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The sections in this article are Introduction Classification Variety of Materials and Focus Target Properties Structure–Activity Relationships Effect of Sulfate and Other Oxo‐Anions Preparation Routes Formation of Primary Solid Formation of Pure Hydrous Zirconia Formation of Sulfate‐Containing Hydrous Zirconia Template‐Directed Formation of Primary Solid Commercially Available Precursors Anion‐Modification of Primary Solid Addition of Oxo‐Anions to Primary Solid in Liquid Medium Sulfation of Primary Solid via Gas Phase Introduction of Oxo‐Anions Using Solid Precursors Addition of Promoters (Optional) Promoters Structure–Activity Relationships Effect of Promoters Addition of Promoters Calcination Events Occurring During Calcination Effect of Bed Volume and Packing Effect of Calcination Temperature on Physical Properties Effect of Calcination Temperature on Catalytic Performance Effect of Holding Time Calcination: A Summary Sulfation of Thermally Treated Crystalline Oxides Sulfation with Aqueous Solutions (Solid–Liquid Phase) Sulfation via Gas Phase (Solid–Gas Phase) Sulfation of Zirconia using Solid Sulfate Precursors Addition of Noble Metals Activation Summary

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“…Plain zirconia (ZrO 2 ) was prepared by calcination of commercial zirconium hydroxide (Zr(OH) 4 , Aldrich) in flowing air at 873 K for 3 h (heating rate 10 K min -1 ). Before sulfation with gaseous SO 3 , the samples (pellets, 355 -710 lm, 0.5 -2 g) were preheated in the quartz tube under N 2 flow (50 mL min -1 ) at 673 K for 2 h, then cooled to 473 K. The SO 3 cylinder was then filled with 50 mL of N 2 and subsequently connected to the flow system.…”

Section: Catalyst Preparation and Handlingmentioning

confidence: 99%

“…Initially, Gates et al [3] suggested a protolytic activation of the C-H bond with the transient formation of a carbonium ion, based on reactions of alkanes catalyzed by liquid superacids. This hypothesis has been later criticized, because experimental and theoretical investigations demonstrated that SZ is not a superacid [4,5].…”

Section: Introductionmentioning

confidence: 99%

Activation of Light Alkanes on Sulfated Zirconia

Olindo

Lercher

2006

Chemie Ingenieur Technik

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The present contribution reviews recent experiments of our group towards the synthesizing and understanding of highly reactive sulfate-modified zirconia. It is shown that in the absence of Pt, the catalytic activity depends upon the ability to oxidize a small fraction of the alkanes to alkenes. The alkenes form sec-carbenium ions with Brønsted acid sites and isomerize via carbenium ion/alkoxy intermediates. Alkane activation/conversion propagates through hydride transfer from n-butane to the tert-butyl carbenium ion. A kinetic model accounting for the elementary steps is proposed and catalyst preparation strategies are reported.

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Comparaison des propriétés catalytiques de quelques oxydes sulfatés

Cited by 6 publications

References 0 publications

The Balance Between Reactivity and Stability of Modified Oxide Surfaces Illustrated by the Behavior of Sulfated Zirconia Catalysts

The Balance Between Reactivity and Stability of Modified Oxide Surfaces Illustrated by the Behavior of Sulfated Zirconia Catalysts

Oxo‐Anion Modified Oxides

Activation of Light Alkanes on Sulfated Zirconia

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