Calorimetric study of vanadium pentoxide catalysts used in the reaction of ethane oxidative dehydrogenation

Bars, J. Le; Vedrine, J. C.; Auroux, A.; Pommier, B.; Pajonk, G.M.

doi:10.1021/j100184a035

Cited by 56 publications

(23 citation statements)

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“…The pure vanadium oxide (V 2 O 5 ) is known to be rather inactive (Oyama and Somorjai, 1990 ;Le Bars et al , 1992 ) and has also unfavorable mechanical properties when stable pellets or monoliths are needed (Chary et al , 2003 ;Reddy and Varma, 2004 ). For these reasons, vanadia is typically deposited onto high -surfacearea supports like γ -alumina, silica, zeolites, titania or zirconia.…”

Section: Catalysts and Structure -Activity Relationsmentioning

confidence: 99%

Catalysis and Reaction Kinetics of a Model Reaction

et al. 2010

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The development of new and the improvement of existing reactor concepts is diffi cult without understanding the reaction mechanism and -if a catalyst is used -its operation principles. In the ideal case an accurate kinetic model with detailed structure -activity relations would be available. However, in industrial practice in general only simplifi ed strategies are applied in order to minimize experimental effort and to reduce the complexity of the corresponding mathematical expressions. Often simplifi ed kinetic models of the power law type are used to describe reaction rates and catalytic performance for a limited parameter range. Nevertheless, for the understanding and the correct prediction of the performance of alternative reactor concepts, as the membrane reactors treated in this book, a more detailed understanding of the kinetic relations is essential. In membrane reactors the concentration profi les of the reactants and the contact time profi les in the catalyst bed are infl uenced simultaneously. A reliable kinetic model has to describe also the reaction behavior for conditions which are far from those present in conventional packed -bed reactors.In order to deliver reliable data for the comparison between conventional and membrane reactors on the one hand, and between different membrane reactor concepts on the other, it is important to study the same reaction system and to apply the same catalyst. In this and the following chapters, the focus is set on the catalyzed oxidative dehydrogenation of ethane ( ODHE ). Although this reaction is currently far from a wide industrial application, it has several advantages for the purpose of this conceptual study:• The expected reaction network is limited to a rather low number of main products and byproducts, which facilitates mechanistic as well as kinetic studies.• There are no condensable products under reaction conditions, which is benefi cial for monitoring the reactor performance with high accuracy.

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Section: Catalysts and Structure -Activity Relationsmentioning

confidence: 99%

Catalysis and Reaction Kinetics of a Model Reaction

et al. 2010

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“…These spectra have been utilized as a sensitive probe of the circumstellar environment and are of significant importance in modeling of the stellar atmospheres. VO and other oxides of vanadium are also of chemical and industrial importance because of their use in optical devices, semiconductors, catalysts, and coatings [6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Emission spectroscopy of a new 2Δ–12Δ system of VO

Ram

Bernath

2005

Journal of Molecular Spectroscopy

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“…It is possibly that the reduction of the oxidized surface vanadium species is responsible for the rather low selectivities towards alkenes in the beginning of the dehydrogenation reaction. In addition, Le Bars et al 29 suggested that the better selectivity seems to be a characteristic of the reduced surface.…”

Section: Selectivitymentioning

confidence: 99%

The influence of the amount and impregnation sequence of potassium on the catalytic performance of VOx/Al2O3 for the non-oxidative dehydrogenation of n-butane

Volpe

García

2012

J. Braz. Chem. Soc.

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A dehidrogenação não-oxidativa de n-butano foi estudado usando catalisadores de vanádio suportados em alumina e potássio como promotor (a 873 K e pressão atmosfera), a fim de se explorar a influência da quantidade e da ordem de agregação do metal alcalino na atividade catalítica e seletividade de olefinas. A atividade e seletividade da dehidrogenação não-oxidativa diminuíram com o aumento da razão molar K/V. O melhor desempenho catalítico foi obtido com 1 wt.% de potássio e quando o promotor foi agregado pela primeira vez nos catalisadores de vanádio suportados em alumina. A ordem de agregação do promotor tem efeitos na atividade catalítica. Dados de TPR (redução à temperatura programada) indicam que menos espécies de vanádio são acessíveis à redução quando baixa quantidade (1 wt.%) de promotor metal alcalino foi impregnada no catalisador antes do vanádio. Após tratamento de regeneração, estes catalisadores não recuperam a plena atividade. Tendo em conta os resultados de TPR, essa desativação do catalisador pode estar relacionada com a transformação estrutural irreversível de espécies de óxido de vanádio superficiais pelo potássio.The non-oxidative dehydrogenation of n-butane was studied over potassium-promoted supported vanadium alumina catalysts (at 823 K under atmosphere pressure) to explore the influence of the amount and the order of potassium aggregation on the catalytic activity and selectivity towards olefins. The non-oxidative dehydrogenation activity and selectivity decreased with increasing K/V molar ratio. The best catalytic performance was obtained with 1 wt.% of potassium loading and when the promoter was first aggregated in the supported vanadium alumina catalysts. The order of promoter aggregation has effects in the catalytic activity. TPR (temperature programmed reduction) data indicate that less vanadium species are accessible to the reduction when low amount (1 wt.%) of alkali metal promoter was first introduced in these samples. After regeneration treatment, these promoted catalysts did not recover the full activity. Taking in account TPR results, this catalyst deactivation may be related to the irreversible structural transformation of surface vanadium oxide species by potassium.

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Calorimetric study of vanadium pentoxide catalysts used in the reaction of ethane oxidative dehydrogenation

Cited by 56 publications

References 1 publication

Catalysis and Reaction Kinetics of a Model Reaction

Catalysis and Reaction Kinetics of a Model Reaction

Emission spectroscopy of a new 2Δ–12Δ system of VO

The influence of the amount and impregnation sequence of potassium on the catalytic performance of VOx/Al2O3 for the non-oxidative dehydrogenation of n-butane

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