Ethane dehydrogenation on Pt/Mg(Al)O and PtSn/Mg(Al)O catalysts

Galvita, Vladimir; Siddiqi, Georges; Sun, Pingping; Bell, Alexis T.

doi:10.1016/j.jcat.2010.01.016

Cited by 218 publications

(285 citation statements)

References 65 publications

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“…[31][32][33][34][35][36] Wet incipient impregnation and incorporation of the active metals in the support appear to offer promising perspectives for implementation at a larger scale. 2,37,38 Indeed, incorporation of the active metals within the support via a one pot synthesis is an easy and reproducible route for bimetallic catalyst synthesis. For propane dehydrogenation into propene, incorporation of the active metals in a hydrotalcite-based support has already proven to yield superior catalysts when compared with wet incipient impregnation.…”

Section: Ch 3 Ch 2 Oh ⇌ Ch 3 Cho + Hmentioning

confidence: 99%

“…39 Via the incorporation of the active materials in a single-phase hydrotalcite-based precursor, stable nanoparticle catalysts are obtained after calcination and reduction. [37][38][39][40][41][42][43][44][45] Hydrotalcite-based catalysts currently gain interest due to promising properties, such as active phase dispersion and stability, both in metal and in base catalysis. [38][39][40][41][42][43][44][45][46][47][48][49][50][51] Their composition is denoted as .…”

Section: Ch 3 Ch 2 Oh ⇌ Ch 3 Cho + Hmentioning

confidence: 99%

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Formation and stability of an active PdZn nanoparticle catalyst on a hydrotalcite-based support for ethanol dehydrogenation

Waele

Galvita

Poelman

et al. 2017

Catal. Sci. Technol.

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A hydrotalcite-based PdZn nanoparticle catalyst, PdZn/MgĲAl)ĲPd)ĲZn)O x has been synthesized via a onepot procedure. The activation comprising H 2 and air treatmentĲs) allows tuning the nanoparticle formation and, hence, the catalyst performance. Based on an elaborate set of characterization data from EXAFS, in situ XRD, STEM and CO chemisorption, it is concluded that single reduction leads to the formation of Pdrich alloy nanoparticles, i.e., a PdZn shell with a Pd core. Cycled reduction, i.e., 3 subsequent hydrogen and air treatments, ensures the formation of more homogeneously mixed PdZn nanoparticles. Compared with a PdZn/ZnO reference catalyst, the nanoparticles obtained after cycled reduction exhibit a higher initial average turnover frequency in ethanol dehydrogenation, i.e., 7.0 molEtOH (mol Pd s) −1 rather than 3.2 molEtOH (mol Pd s). An activity loss is observed during the first hours on stream. It is attributed to coking of the Pd sites which are also deemed responsible for acetaldehyde decomposition. Hence, the acetaldehyde selectivity steadily increases during the first hours on stream. Subsequently, the acetaldehyde space time yield and selectivity stabilize at 0.7 × 10 −4 mol s −1 kg −1Pd and 98%, respectively.

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Section: Ch 3 Ch 2 Oh ⇌ Ch 3 Cho + Hmentioning

confidence: 99%

Section: Ch 3 Ch 2 Oh ⇌ Ch 3 Cho + Hmentioning

confidence: 99%

Formation and stability of an active PdZn nanoparticle catalyst on a hydrotalcite-based support for ethanol dehydrogenation

Waele

Galvita

Poelman

et al. 2017

Catal. Sci. Technol.

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“…5 In addition, Pt and Pt-based catalysts on hydrotalcite (Mg(Al)O) increase the activity of dehydrogenation of ethane to ethene. 2,6,7 Several studies have shown the catalytic capabilities of stoichiometric and defective MgO(100) surfaces, as well as transition metal catalysts supported on such. 8−12 Successive dehydrogenation to alkynes, and methane production from cracking, can result in coke fouling.…”

Section: Introductionmentioning

confidence: 99%

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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“…5,6 A number of authors have shown that superior catalyst activity, selectivity, and stability can be achieved by alloying Pt with Sn and by adding hydrogen to the alkane feed. 5,[7][8][9][10][11] Both aspects have been addressed in recent experiments of our group on the dehydrogenation of ethane over Pt x Sn 100Àx clusters (70 r x r 100). 12 First, it has been observed that the presence of hydrogen suppresses the formation of coke and enhances the rate of alkane dehydrogenation, if the ratio of H 2 to alkane is below about 1.5.…”

Section: Introductionmentioning

confidence: 99%

Subnanometer-sized Pt/Sn alloy cluster catalysts for the dehydrogenation of linear alkanes

Hauser

Gomes

Bajdich

et al. 2013

Phys. Chem. Chem. Phys.

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The reaction pathways for the dehydrogenation of ethane, propane, and butane, over Pt are analyzed using density functional theory (DFT). Pt nanoparticles are represented by a tetrahedral Pt 4 cluster. The objectives of this work were to establish which step is rate limiting and which one controls the selectivity for forming alkenes as opposed to causing further dehydrogenation of adsorbed alkenes to produce precursors responsible for catalyst deactivation due to coking. Further objectives of this work are to identify the role of adsorbed hydrogen, derived from H 2 fed together with the alkane, on the reaction pathway, and the role of replacing one of the four Pt atoms by a Sn atom. A comparison of Gibbs free energies shows that in all cases the rate-determining step is cleavage of a C-H bond upon alkane adsorption. The selectivity to alkene formation versus precursors to coking is dictated by the relative magnitudes of the activation energies for alkene desorption and dehydrogenation of the adsorbed alkene. The presence of an adsorbed H atom on the cluster facilitates alkene desorption relative to dehydrogenation of the adsorbed alkene. Substitution of a Sn atom in the cluster to produce a Pt 3 Sn cluster leads to a downward shift of the potential energy surface for the reaction and causes an increase of the activity of the catalyst as suggested by recent experiments due to the lower net activation barrier for the rate limiting step. However, the introduction of Sn does not alter the relative activation barriers for gas-phase alkene formation versus loss of hydrogen from the adsorbed alkene, the process leading to the formation of coke precursors.

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Ethane dehydrogenation on Pt/Mg(Al)O and PtSn/Mg(Al)O catalysts

Cited by 218 publications

References 65 publications

Formation and stability of an active PdZn nanoparticle catalyst on a hydrotalcite-based support for ethanol dehydrogenation

Formation and stability of an active PdZn nanoparticle catalyst on a hydrotalcite-based support for ethanol dehydrogenation

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

Subnanometer-sized Pt/Sn alloy cluster catalysts for the dehydrogenation of linear alkanes

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