Oxidative dehydrogenation of ethane over alumina-supported Pd catalysts. Effect of alumina overlayer

Fu, Baosong; Lu, Junling; Stair, Peter C.; Xiao, Guomin; Kung, Mayfair C.; Kung, Harold H.

doi:10.1016/j.jcat.2012.10.023

Cited by 25 publications

(20 citation statements)

References 28 publications

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“…Recently, over-coating Pd and Pt nanoparticles with thin alumina layers synthesized by atomic layer deposition (ALD) using trimethylaluminium (TMA) and water as precursors has been shown to prevent catalyst deactivation. [10][11][12][13][14][15] ALD is a variation of chemical vapor deposition (CVD) based on self-limiting reactions between gaseous precursors and a solid substrate typically covered with functional groups. 16 TMA is one of the most widely used ALD organometallic precursors, and the TMA-water ALD system is one of the most studied (see for instance reference 17 and references therein).…”

Section: Introductionmentioning

confidence: 99%

Surface Chemistry of Trimethylaluminum on Pd(111) and Pt(111)

et al. 2015

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The behavior of trimethylaluminium (TMA) was investigated on the surfaces of Pt(111) andPd(111) single crystals. TMA was found to dissociatively adsorb on both surfaces between 300 -473 K. Surfaces species observed by high-resolution electron energy loss spectroscopy (HREELS) and X-ray photoelectron spectroscopy (XPS) after TMA adsorption at 300 K included Al-CH 3 and CH x,ads (x = 1, 2, or 3) on Pt(111), and ethylidyne (CCH 3 ), CH x,ads (x = 1, 2, or 3), and metallic Al on Pd(111). Density functional theory (DFT) calculations predicted methylaluminum (MA, Al-CH 3 ) to be the most kinetically favorable TMA decomposition product on (111) terraces of both surfaces, however, HREELS signatures for Al-CH 3 were detected only on Pt(111), whereas ethylidyne was observed on Pd(111). XPS demonstrated higher amount of carbonaceous species on Pt(111) than on Pd (111) DFT calculations showed that further dissociation of MA to metallic aluminum and methyl groups to be more kinetically favorable on step sites of both metals. In our proposed reaction mechanism, MA migrates to and dissociates at Pd(111) steps at 300 K forming adsorbed methyl groups and metallic Al. Some methyl groups dehydrogenate and recombine forming ethylidyne. Metallic Al or ejected Pd atoms from steps diffuse across Pd(111) terraces until coalescing into irregularly shaped islands on terraces or steps, as observed by scanning tunneling microscopy (STM). Upon heating above 300 K, the Pd-Al alloy diffuses into the Pd bulk. On Pt(111), a high coverage of carboncontaining species following TMA adsorption at 300 K prevented MA diffusion and dissociation at steps, as evidenced by isolated clusters of MA in STM images. Heating above 300 K resulted in MA dissociation, but no Pt-Al alloy formation was observed. We conclude that the differing abilities of Pd and Pt to hydrogenate carbonaceous species plays a key role in MA dissociation and alloy formation, and, therefore, the adsorption and dissociation chemistry of TMA depends on properties of the metal substrate surface and determines thin film morphology and composition.

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Section: Introductionmentioning

confidence: 99%

Surface Chemistry of Trimethylaluminum on Pd(111) and Pt(111)

et al. 2015

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“…Thus, and as a result, the catalyst has to be subsequently re-oxidized by gas phase oxygen. This type of mechanism is known as the ODH redoxmechanism, as described by Equation (36).…”

Section: Kinetics and Reaction Mechanisms Of Propane Odh Over Vanadiumentioning

confidence: 99%

“…In this respect, when O 2 is near depletion, non-oxidative processes dominate the ODH, with the CO 2 and H 2 O formed also being consumed. These conditions enhance the overall H 2 yields [36].…”

Section: Introductionmentioning

confidence: 97%

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Propane Oxidative Dehydrogenation on Vanadium-Based Catalysts under Oxygen-Free Atmospheres

Rostom

Lasa

2020

Catalysts

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Catalytic propane oxidative dehydrogenation (PODH) in the absence of gas phase oxygen is a promising approach for propylene manufacturing. PODH can overcome the issues of over-oxidation, which lower propylene selectivity. PODH has a reduced environmental footprint when compared with conventional oxidative dehydrogenation, which uses molecular oxygen and/or carbon dioxide. This review discusses both the stoichiometry and the thermodynamics of PODH under both oxygen-rich and oxygen-free atmospheres. This article provides a critical review of the promising PODH approach, while also considering vanadium-based catalysts, with lattice oxygen being the only oxygen source. Furthermore, this critical review focuses on the advances that were made in the 2010–2018 period, while considering vanadium-based catalysts, their reaction mechanisms and performances and their postulated kinetics. The resulting kinetic parameters at selected PODH conditions are also addressed.

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“…20,21 In all cases, γ-Al 2 O 3 (with a surface area ranging 150-210 m 2 g −1 ) was used. 22,23 Mesoporous alumina was used as a support of vanadium oxide in the ODH of ethane, 19,22 showing high productivity towards ethylene as a consequence of a remarkable dispersion of vanadium on the support surface. However, an even better metal dispersion can be achieved using γ-Al 2 O 3 as the support, 8,12,16,18,24 which makes it more interesting for use in ODH of n-butane.…”

Section: Introductionmentioning

confidence: 99%

Effect of O₂, CO₂ and N₂O on Ni–Mo/Al₂O₃ catalyst oxygen mobility in n-butane activation and conversion to 1,3-butadiene

Dasireddy

Huš

Likozar

2017

Catal. Sci. Technol.

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Oxidative dehydrogenation of ethane over alumina-supported Pd catalysts. Effect of alumina overlayer

Cited by 25 publications

References 28 publications

Surface Chemistry of Trimethylaluminum on Pd(111) and Pt(111)

Surface Chemistry of Trimethylaluminum on Pd(111) and Pt(111)

Propane Oxidative Dehydrogenation on Vanadium-Based Catalysts under Oxygen-Free Atmospheres

Effect of O₂, CO₂ and N₂O on Ni–Mo/Al₂O₃ catalyst oxygen mobility in n-butane activation and conversion to 1,3-butadiene

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Oxidative dehydrogenation of ethane over alumina-supported Pd catalysts. Effect of alumina overlayer

Cited by 25 publications

References 28 publications

Surface Chemistry of Trimethylaluminum on Pd(111) and Pt(111)

Surface Chemistry of Trimethylaluminum on Pd(111) and Pt(111)

Propane Oxidative Dehydrogenation on Vanadium-Based Catalysts under Oxygen-Free Atmospheres

Effect of O2, CO2 and N2O on Ni–Mo/Al2O3 catalyst oxygen mobility in n-butane activation and conversion to 1,3-butadiene

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Effect of O₂, CO₂ and N₂O on Ni–Mo/Al₂O₃ catalyst oxygen mobility in n-butane activation and conversion to 1,3-butadiene