Dehydrogenation and oxydehydrogenation of paraffins to olefins

Bhasin, Madan M.; McCain, J.H; Vora, B.V.; Imai, T.; Pujadó, P. R.

doi:10.1016/s0926-860x(01)00816-x

Cited by 628 publications

(474 citation statements)

References 38 publications

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“…The concentration of the solution was selected in order to obtain a V final concentration of 5 wt.% and the vanadium aggregate was always by grafting method from toluene solution of V(AcAc) 3 . This vanadium loading was chosen because it is well below the loading required for full monolayer coverage of the support (12.6 wt.% V).…”

Section: Methodsmentioning

confidence: 99%

“…The concentration of the potassium nitrate solution was selected in order to obtain a 1 or 10 wt.% concentration of the alkali metal. The samples were dried at 383 K overnight and finally calcined at 873 K for 1 h. Afterwards, they were impregnated with solution of V(AcAc) 3 in toluene, in which the concentration corresponds to a target loading of 5 wt.% of vanadium. Then, the material was filtered and washed with toluene.…”

Section: Methodsmentioning

confidence: 99%

“…2 Paraffin dehydrogenation is a strongly endothermic reaction that is limited by chemical equilibrium and, according with Le Chatelier's principle, higher conversion requires either higher temperatures or lower pressures. 3 The temperature required for the dehydrogenation of light paraffins is much higher than for heavy paraffins. For 40% conversion, the dehydrogenation of propane requires a temperature of at least about 853 K, while dodecane can be theoretically dehydrogenated to the same extent at only 723 K. The equilibrium conversion increases at higher Vol.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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“…The bimetallic Pt-Sn/γ-Al 2 O 3 catalysts have been extensively studied and a number of active and selective catalysts have been developed and patented [2][3][4][5][6][7][8][9]. It is generally agreed that the promoter effect of Sn is a result of combined influence of geometric as well as electronic factors [ 6,11,12 ]. γ-Al 2 O 3 has been widely used as supporting material for the dehydrogenation catalysts, but its acidity leads to proceeding of hydrocarbons cracking and hence to coke formation.…”

mentioning

confidence: 99%

“…Efforts are still underway to improve the Pt-Sn/γ-Al 2 O 3 catalyst in order to increase its activity, selectivity and ability easily to be regenerated without appreciable loss of activity [ 12 ]. The addition of alkaline earth elements to the catalyst composition change the surface acidity of the catalyst and might be very much beneficial for light paraffins dehydrogenation reaction [ 13 ].…”

mentioning

confidence: 99%

Correlation between Melting Temperatures of Alkaline Earth Elements and Their Effect as Promoters of Pt-Sn/γ-Al2O3 Catalyst in Propane Dehydrogenation Reaction

Alhamed¹,

Umar²,

Daous³

et al. 2013

Proceeding BAS

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Pt-Sn/Al 2 O 3 catalyst is well known to have good activity and selectivity for propane dehydrogenation reaction but suffers quick deactivation due to substantial coke formation. In this study effort has been made to improve the characteristics of this catalyst by making tri-metallic catalyst supported on gamma alumina. Pt-Sn-Ca/Al 2 O 3 catalyst was found best among these, especially in yielding improved results in terms of conversion, selectivity, yield and less coke formation. Calcium contents of the catalyst composition were also varied to attain the most suitable amount. Propane conversion, propylene selectivity and yield at optimum operation conditions were: 43.2%, 95.3% and 35.8% respectively at 575 • C. The catalysts were characterized by TEM, XPS, SEM-EDX, H2-TPR, NH3-TPD, CO titration and TGA techniques.

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Catalyst Characterization—Heterogeneous

Stavitski

Beale

Weckhuysen

2010

Encyclopedia of Catalysis

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The study of catalysts under in‐situ conditions enables the catalyst scientist to identify and understand the important steps, e.g., the formation of important reaction intermediates and active sites, and stages in a catalyst?s lifetime, such as activation/deactivation. The development of characterization methods as well as the design and construction of appropriate in‐situ cells and reactor probes are inevitable in order to obtain such insight. Both spectroscopic and scattering techniques have been used in attempt to understand quantitative structure/composition‐activity/selectivity relationships in catalysis. Armed with such detailed knowledge about the catalyst, it is then possible for scientists to design, in a more rational way, new and efficient catalysts for sustainable production of bulk and fine chemicals as well as for the removal of harmful compounds in industrial catalytic processes. This chapter provides an overview of the in‐situ characterization techniques available for investigation of catalytic materials. The possibilities and limitations of the methods are discussed and illustrated with numerous case studies.

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Dehydrogenation and oxydehydrogenation of paraffins to olefins

Cited by 628 publications

References 38 publications

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

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

Correlation between Melting Temperatures of Alkaline Earth Elements and Their Effect as Promoters of Pt-Sn/γ-Al2O3 Catalyst in Propane Dehydrogenation Reaction

Catalyst Characterization—Heterogeneous

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