Oxidative dehydrogenation of propane on silica (SBA-15) supported vanadia catalysts: A kinetic investigation

Dinse, Arne; Khennache, Sonia; Frank, Benjamin; Heß, Christian; Herbert, Rita; Wrabetz, Sabine; Schlögl, Robert; Schomäcker, Reinhard

doi:10.1016/j.molcata.2009.03.008

Cited by 48 publications

(41 citation statements)

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“…[48] A kinetic investigation for a V/SBA-15 catalyst with 2.7 wt% vanadia yielded a significantly lower apparent activation energy of only 103 kJ/mol. [52] The activation energies measured here are simi lar for all catalysts. For the low loaded species an excellent reproducibility is observed for repeated measurements, also when using a fresh catalyst (squares, circles, and triangles in left panel of Fig.…”

Section: Catalytic Activity In the Odh Of Propanementioning

confidence: 76%

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Role of dispersion of vanadia on SBA-15 in the oxidative dehydrogenation of propane

et al. 2010

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A series of vanadia catalysts supported on the mesoporous silica SBA-15 are synthesized using an automated laboratory reactor. The catalysts contain from 0.6 up to 13.6V atoms/nm 2 and are structurally characterized by various techniques (BET, XRD, SEM, TEM, Raman, IR, UV/Vis).Samples containing up to 3.1V/nm 2 are structurally rather similar. They all contain a mixture of tetrahedral (VOx)n species, both monomeric and oligomeric. The ratio of monomeric and oligomeric species depends on the vanadia loading. At the highest loading of 13.6V/nm 2 , in addition to tetrahedral (VOx)n, also substantial amounts of three-dimensional, bulk-like V2O5 are present in the catalyst. The structural similarity of the lowloaded catalysts is reflected in their alike catalytical activity during the oxidative dehydrogenation (ODH) of propane between 380 and 480 °C. Propene, CO, and CO2 are formed as reaction products, while neither the formation of ethene nor acrolein or acrylic acid is observed in other than trace amounts. The activation energy for ODH of propane is 140 kJ/mol. The catalyst with the highest loading yields varying activation energies for different reaction conditions, which is probably related to rearrangements between bulk-like and dispersed, two-dimensional (VOx)n. Rather than the monomer to oligomer ratio, the ratio of two-dimensional to three-dimensional vanadia seems to be crucial for the catalytic properties of silica supported vanadia in the ODH of propane.

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Section: Catalytic Activity In the Odh Of Propanementioning

confidence: 76%

“…Assuming a first order rate law, [45,52] the reaction order of propane is close to one (Table 2). This reflects the participation of propane in the rate determining step, which is the abstraction of the first hydrogen atom.…”

Section: Catalytic Activity In the Odh Of Propanementioning

confidence: 90%

Role of dispersion of vanadia on SBA-15 in the oxidative dehydrogenation of propane

et al. 2010

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“…This reflected on catalyst performance [14][15][16] , showing a higher selectivity (at isoconversion) for sample V10Si with 21 respect to its homologue prepared by impregnation (V10Si-i), especially when operating under anaerobic conditions. Similar conclusions, though less evident, may be drawn for sample V10Al when compared with V10Al-i.…”

Section: Survey Of Previous Resultsmentioning

confidence: 99%

Spectroscopic Enlightening of the Local Structure Of VO_X Active Sites in Catalysts for the Odh of Propane

et al. 2012

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Site isolation of V active sites has been often correlated to catalytic performance for the oxidative dehydrogenation (ODH) of propane to propylene. In particular, catalyst selectivity seems favoured by high V dispersion. The latter property is hardly attainable by traditional preparation methods, especially by impregnation except at very low V loading, which however may lead to a too high surface exposure of the acidic sites of the support. In this paper, the effect of the preparation procedure on catalyst properties has been investigated, particularly considering catalysts prepared by flame pyrolysis, a synthesis method which induced a very high V dispersion also at relatively high vanadium loading.Transmission electron microscopy also allowed us to assess V oxide dispersion depending on both the support type and the preparation method. Furthermore, the local structure of the V active sites has been deeply investigated by X-ray Absorption Spectroscopy, allowing us to propose a possible structure of the active sites.The average oxidation state of surface V species was then studied by X-ray Photoelectron Spectroscopy (XPS), showing a role of V oxidation state on catalyst selectivity. The catalytic performance has been interpreted on the basis of V species and catalyst acidity (as measured by IR spectroscopy), another fundamental parameter that in turn results to be correlated with V dispersion on different supports. More selective catalysts were indeed characterized by the presence of weaker Brønsted acidic sites.Keywords: Oxidative dehydrogenation (ODH) of propane; Propylene production; V-based catalysts; X-ray absorption. Page 2 of 53 ACS Paragon Plus EnvironmentThe Journal of Physical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 3 -IntroductionLight olefins are important building blocks for polymers and intermediates industry 1 . The need for light olefins is progressively growing, with a higher rate for propene, leading to the necessity of alternative production routes 2 . Direct dehydrogenation can be an interesting alternative when low value feedstock is available. However, it is an endothermal reaction needing a high energy input, it is equilibrium controlled and the catalyst may be easily deactivated by coking. The oxidative dehydrogenation (ODH) of light paraffins to the corresponding olefins has been proposed as a means to overcome all these limitations. In addition, oxygen limits severe catalyst coking 3 . In spite of the considerable attention paid to this process and testified by a certain number of patents (see e.g. 4,5 and references therein), the ODH technology can be hardly considered mature and it has not yet reached industrial application due to selectivity issues. Indeed, oxygen should ideally consume H 2 , but paraffins and (most of all) olefins combustion is an unavoidable side reaction, w...

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“…The yield increased with temperature, underwent a sudden increase at T tran and then remained almost constant. 15,47 Therefore, the selective oxidation of propane is more sensitive to temperature so that higher temperatures elevate the selectivity to propene at constant conversion. Investigation of Y tran (yield above T tran ) at different feed compositions indicated the existence of a maximum value for yield on increasing C 3 /O 2 (Fig.…”

Section: Zaynali and Alavimentioning

confidence: 99%

Higher propene yield by tailoring operating conditions of propane oxidative dehydrogenation over V2O5/γ-Al2O3

Zaynali

Alavi

2015

JSCS

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Supported vanadia catalysts were successfully synthesized using wet impregnation of γ-alumina to study propane oxidative dehydrogenation (POD).The prepared catalysts were characterized by X-ray diffraction analysis, specific surface area determination, and temperature programmed reduction tests. Over a broad temperature range (340 to 630 °C), the effects of vanadia loading (2.7, 5.4, and 9 wt. %) and propane to oxygen ratio (3:1 to 1:3) were thoroughly investigated on propane conversion as well as propene yield at atmospheric pressure. The results indicated that on increasing the vanadia content, the activity of catalyst increased while the selectivity to propene decreased monotonically. With increasing temperature from 340 to 630°C, the yield to propene showed an ascending behavior for all catalyst samples. The yield to propene exhibited a maximum on changing the propane to oxygen ratio from 3:1 to 1:3. The yield increased with increasing oxygen partial pressure in the feed until an equimolar ratio of propane and oxygen and then it declined with further increase in the oxygen partial pressure. A maximum propene yield of 17 % was experienced on the catalyst with 2.7 wt. % vanadia at a temperature of 550 °C.

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Oxidative dehydrogenation of propane on silica (SBA-15) supported vanadia catalysts: A kinetic investigation

Cited by 48 publications

References 28 publications

Role of dispersion of vanadia on SBA-15 in the oxidative dehydrogenation of propane

Role of dispersion of vanadia on SBA-15 in the oxidative dehydrogenation of propane

Spectroscopic Enlightening of the Local Structure Of VO_X Active Sites in Catalysts for the Odh of Propane

Higher propene yield by tailoring operating conditions of propane oxidative dehydrogenation over V2O5/γ-Al2O3

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Oxidative dehydrogenation of propane on silica (SBA-15) supported vanadia catalysts: A kinetic investigation

Cited by 48 publications

References 28 publications

Role of dispersion of vanadia on SBA-15 in the oxidative dehydrogenation of propane

Role of dispersion of vanadia on SBA-15 in the oxidative dehydrogenation of propane

Spectroscopic Enlightening of the Local Structure Of VOX Active Sites in Catalysts for the Odh of Propane

Higher propene yield by tailoring operating conditions of propane oxidative dehydrogenation over V2O5/γ-Al2O3

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Spectroscopic Enlightening of the Local Structure Of VO_X Active Sites in Catalysts for the Odh of Propane