Oxidative Dehydrogenation of Propane on γ-Al2O3 Supported Vanadium Oxides

Eon, Jean‐Guillaume; Olier, R.; Volta, J.C.

doi:10.1006/jcat.1994.1040

Cited by 194 publications

(81 citation statements)

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“…Since the demand for propylene is increasing day by day, efforts are being made to develop processes for producing propylene from propane, particularly by catalytic oxidative dehydrogenation of propane (Chaar et al, 1988;Sam et al, 1990;Smits et al, 1991Smits et al, , 1995Burch and Crabb, 1993;Corma et al, 1993a,b;Huff and Schmidt, 1994;Gao et al, 1994a,b;Yoon et al, 1994;Eon and Volta, 1994;Bharadwaj and Schmidt, 1995;Blasco et al, 1995;Mamedov and Corberan, 1995;Parmaliana et al, 1996;Watling et al, 1996;Lee et al, 1997). Propylene with high yields has also been obtained by the noncatalytic oxidative dehydrogenation of propane (Burch and Crabb, 1993).…”

Section: Introductionmentioning

confidence: 95%

Simultaneous thermal cracking and oxidation of propane to propylene and ethylene

1998

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Section: Introductionmentioning

confidence: 95%

Simultaneous thermal cracking and oxidation of propane to propylene and ethylene

1998

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“…Other studies (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18) measuring spectra at ambient temperature between 1 and 5 eV. The Kubelka-Munk function (F(R ∞ )) was used to convert diffuse reflectance data into absorption spectra using MgO as a standard (22).…”

Section: Introductionmentioning

confidence: 99%

Effect of Catalyst Structure on Oxidative Dehydrogenation of Ethane and Propane on Alumina-Supported Vanadia

Argyle

Chen

Bell

et al. 2002

Journal of Catalysis

311

281

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The catalytic properties of Al 2 O 3 -supported vanadia with a wide range of VO x surface density (1.4-34.2 V/nm 2 ) and structure were examined for the oxidative dehydrogenation of ethane and propane. UV-visible and Raman spectra showed that vanadia is dispersed predominately as isolated monovanadate species below ~2.3 V/nm 2 . As surface densities increase, two-dimensional polyvanadates appear (2.3-7.0 V/nm 2 ) along with increasing amounts of V 2 O 5 crystallites at surface densities above 7.0 V/nm 2 . The rate constant for oxidative dehydrogenation (k 1 ) and its ratio with alkane and alkene combustion (k 2 /k 1 and k 3 /k 1 , respectively) were compared for both alkane reactants as a function of vanadia surface density. Propene formation rates (per V-atom) are ~8 times higher than ethene formation rates at a given reaction temperature, but the apparent ODH activation energies (E 1 ) are similar for the two reactants and relatively insensitive to vanadia surface density. Ethene and propene formation rates (per V-atom) are strongly influenced by vanadia surface density and reach a maximum value at intermediate surface densities (~8 V/nm 2 ). The ratio of k 2 /k 1 depends weakly on reaction temperature, indicating that activation energies for alkane combustion and ODH reactions are similar. The ratio of k 2 /k 1 is independent of surface density for ethane, but increase slightly with vanadia surface density for propane, suggesting that isolated structures prevalent at low surface densities are slightly more selective for alkane dehydrogenation reactions. The ratio of k 3 /k 1 decreases markedly with increasing reaction temperature for both ethane and propane ODH. Thus, the apparent activation energy for alkene combustion (E 3 ) is much lower than that for alkane dehydrogenation (E 1 ) and the difference between these two activation energies decreases with increasing surface density. The lower alkene selectivities observed at high vanadia surface densities are attributed to an increase in alkene adsorption enthalpies with increasing vanadia surface density. The highest yield of alkene is obtained for catalysts containing predominantly isolated monovanadate species and operated at high temperatures that avoid homogeneous reactions (<~800 K).2

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“…[8][9][10][11] What remains unclear, though, is which of the three different types of oxygen present at the surface of V 2 O 5 are involved in the mechanism of propane ODH, and evidence has been presented for all three forms. Experimental studies by Oyama and coworkers 12 have proposed that singly coordinated vanadyl oxygen, O (1), is the active center for SiO 2 -supported V 2 O 5 , whereas Eon et al 13 have proposed that the active site on γ-Al 2 O 3 -supported V 2 O 5 are 2-fold coordinated, bridging oxygen atoms, O (2). Quantum chemical calculations of the binding strength of H atoms with the surface of V 2 O 5 have been used in an attempt to ascertain the relative reactivity of different forms of oxygen.…”

Section: Introductionmentioning

confidence: 99%

Density Functional Theory Calculations of the Oxidative Dehydrogenation of Propane on the (010) Surface of V₂O₅^†

et al. 2000

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Density functional theory and the calculations of oxygen nucleophilicity have been applied to an analysis of the oxidative dehydrogenation (ODH) of propane on the (010) surface of V 2 O 5 . These calculations show that the energetically preferred initial step is the dissociative adsorption of propane to form i-propoxide and hydroxyl species. Two VdO groups [O(1)] bonded by a V-O-V bridge are required. One of the vanadyl groups attacks the -C atom of propane and is converted to a V-OCH 2 (CH 3 ) 2 species, whereas the other vanadyl group is converted into a V-OH group. The activation barrier for this process is 9.4 kcal/mol. Dissociative adsorption to form an n-propoxide can also occur, but the activation barrier for this process is 14.5 kcal/mol. Propene and water are formed via a concerted process in which an H atom of one of the methyl groups of i-propoxide reacts with an O(3)H group. Exploration of alternative pathways for this step reveals that neither O(1, 2, 3), O(1)H, nor O(2)H are sufficiently reactive. These findings are in good qualitative agreement with experimental observations concerning the mechanism and kinetics of propane ODH.

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Oxidative Dehydrogenation of Propane on γ-Al2O3 Supported Vanadium Oxides

Cited by 194 publications

References 0 publications

Simultaneous thermal cracking and oxidation of propane to propylene and ethylene

Simultaneous thermal cracking and oxidation of propane to propylene and ethylene

Effect of Catalyst Structure on Oxidative Dehydrogenation of Ethane and Propane on Alumina-Supported Vanadia

Density Functional Theory Calculations of the Oxidative Dehydrogenation of Propane on the (010) Surface of V₂O₅^†

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Oxidative Dehydrogenation of Propane on γ-Al2O3 Supported Vanadium Oxides

Cited by 194 publications

References 0 publications

Simultaneous thermal cracking and oxidation of propane to propylene and ethylene

Simultaneous thermal cracking and oxidation of propane to propylene and ethylene

Effect of Catalyst Structure on Oxidative Dehydrogenation of Ethane and Propane on Alumina-Supported Vanadia

Density Functional Theory Calculations of the Oxidative Dehydrogenation of Propane on the (010) Surface of V2O5†

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Density Functional Theory Calculations of the Oxidative Dehydrogenation of Propane on the (010) Surface of V₂O₅^†