Alkane dehydrogenation over supported chromium oxide catalysts

Weckhuysen, Bert M.; Schoonheydt, Robert A.

doi:10.1016/s0920-5861(99)00047-4

Cited by 355 publications

(315 citation statements)

References 53 publications

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“…Previously, the authors have shown that both Pt 4 and Pt 5 undergo morphological modification when attached to MgO. 11,12 For the case of Pt 4 the cluster broadens, with three Pt atoms coordinating to surface O atoms and one Pt atom on top, balancing between metal−metal and metal−oxide bonding.…”

Section: Resultsmentioning

confidence: 99%

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Alloying Pt Sub-nano-clusters with Boron: Sintering Preventative and Coke Antagonist?

2015

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Immobilized Pt clusters are interesting catalysts for dehydrogenation of alkanes. However, surface-deposited Pt clusters deactivate rapidly via sintering and coke deposition. The results reported here suggest that adding boron to oxide-supported Pt clusters could be a "magic bullet" against both means of deactivation. The model systems studied herein are pure and B-doped Pt clusters deposited on MgO(100). The nonstoichiometric boride cluster obtained via such alloying is found to anchor to the support via a covalent B−O bond, and the cluster-surface binding is much stronger than in the case of pure Pt clusters. Additionally, B introduces covalency to the intracluster bonding, leading to structural distortion and stabilization. The energy required to dissociate a Pt atom from a boride cluster is significantly larger than that of pure Pt clusters. These energetic arguments lead to the proposal that sintering via both Ostwald ripening and particle coalescence would be discouraged relative to pure Pt clusters. Finally, it is shown that the affinity to C also drops dramatically for borated clusters, discouraging coking and increasing the selectivity of potential cluster catalysts.

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Section: Resultsmentioning

confidence: 99%

“…In Table 3, the sintering energy penalties and adsorption energies are presented for Pt 4 , Pt 4 B, and Pt 5 . Again, the dissociation channels considered were from the global minima of the deposited clusters, resulting in a Pt monomer attached to the highest-affinity site of the support and the global minima of 5 .…”

mentioning

confidence: 99%

Alloying Pt Sub-nano-clusters with Boron: Sintering Preventative and Coke Antagonist?

2015

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“…Mass fragmentation spectra from an experiment in which the catalyst was first exposed to 12 C-ethane under standard conditions, then flushed with He until no 28 peak was observed in the mass spectrometer, and finally exposed to mono-labelled ethane, 13 CH 3 12 CH 3 (C 2 H 6 :He=2:20 Nml/min, 580°C, 20% ethane conversion), are shown in figure 5. The mass fragments of ethane (figure 5a) and ethene (figure 5b) are both shifted one mass unit higher after introduction of 1) 13 C ethane compared to 12 C ethane.…”

Section: Resultsmentioning

confidence: 99%

“…High-loaded Cr/Al 2 O 3 catalysts have shown to be very active and selective in this reaction and are industrially used at dehydrogenation plants all over the world [1][2][3]. The increasing demand for propene due to the growing polypropylene market, the related use of this catalytic system as well as the catalyst complexity have initiated many research activities in both academia and chemical industries.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Insight in the Ethane Dehydrogenation Reaction over Cr/Al2O3 Catalysts

et al. 2005

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A Cr/Al 2 O 3 alkane dehydrogenation catalyst exhibits a maximum in ethylene yield during an ethane dehydrogenation cycle. Isotopic labelling experiments with monolabelled 13 C-ethane and deuterium were used to elucidate whether the initial activity increase could be due to formation of an active, larger hydrocarbon intermediate on the surface. The results strongly indicate that this is not the case, and instead point to a traditional reaction cycle involving adsorption of ethane to form an ethyl species, followed by desorption of ethene and hydrogen. Transient kinetic data suggest that ethane adsorption is the rate-determining step of reaction.

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“…However, at such high temperatures secondary reactions such as cracking and carbon deposition are also favoured; therefore, the reaction tends to get less selective as temperature and conversion increase. The equilibrium conversion can also be increased by decreasing the pressure and indeed some on-demand dehydrogenation processes operate at partial pressure less than 1 atm often with the use of a diluent in the alkane feed [33]. Carbon deposition during dehydrogenation is a major process problem and limits the time on-stream for the catalysts.…”

Section: Dehydrogenation and Hydrogenation Processes In Trans-hydrogementioning

confidence: 99%

Catalytic upgrading of refinery cracked products by trans-hydrogenation: a review

Garba

Jackson

2016

Appl Petrochem Res

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The production of high premium fuel is an issue of priority to every refinery. The trans-hydrogenation process is devised to convert two low valued refinery cracked products to premium products; the conversion processes involve the combination of dehydrogenation and hydrogenation reaction as a single step process. The paper reviews the recent literature on the use of catalysts to convert low value refinery products (i.e. alkanes and alkynes or alkadienes) to alkenes (olefins) by trans-hydrogenation. Catalysts based on VO x , CrO x and Pt all supported on alumina have been used for the process. However, further studies are still required to ascertain the actual reaction mechanism, mitigating carbon deposition and catalyst deactivation, and the role of different catalysts to optimize the reaction desired products.

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Alkane dehydrogenation over supported chromium oxide catalysts

Cited by 355 publications

References 53 publications

Alloying Pt Sub-nano-clusters with Boron: Sintering Preventative and Coke Antagonist?

Alloying Pt Sub-nano-clusters with Boron: Sintering Preventative and Coke Antagonist?

Mechanistic Insight in the Ethane Dehydrogenation Reaction over Cr/Al2O3 Catalysts

Catalytic upgrading of refinery cracked products by trans-hydrogenation: a review

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