Pt–Ga Model SCALMS on Modified HOPG: Growth and Adsorption Properties

Hohner, Chantal; Kettner, Miroslav; Stumm, Corinna; Schuschke, Christian; Schwarz, Matthias; Libuda, Jörg

doi:10.1007/s11244-019-01167-0

Cited by 11 publications

(39 citation statements)

References 57 publications

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“…Prior to deposition of the IL, we observe CO bands at 2096 and 1848 cm –1 , assigned to ν(CO) top and ν(CO) bridge , respectively . On the Pt(111) surface at 300 K, CO occupies on-top and bridge sites at a saturation coverage of θ = 0.5 (adsorption energy 135 kJ/mol). − Notably, the band intensities do not reflect the abundance of adsorbed species due to differences in the dynamic dipole moments and dipole coupling. , On defect sites, CO binds even stronger than on facet sides, and thus, these are occupied preferentially. ,− …”

Section: Resultsmentioning

confidence: 94%

CO Permeability and Wetting Behavior of Ionic Liquids on Pt(111): An IRAS and PM-IRAS Study from Ultrahigh Vacuum to Ambient Pressure

et al. 2021

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Solid catalysts with ionic liquid layers (SCILLs) show improved performance as compared to ionic liquid (IL)-free catalysts. To realize the beneficial IL-induced modification, the IL layer should be stable under reaction conditions but also permeable for gaseous reactants entering through the IL phase. Herein, we applied (polarization modulation-) infrared reflection absorption spectroscopy ((PM-)IRAS) to investigate the CO permeability of model SCILL systems. We investigated three different IL model systems prepared by physical vapor deposition (PVD) in ultrahigh vacuum (UHV) on atomically clean Pt(111), namely, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([C4C1Pyr][NTf2]), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2C1Im][NTf2]), and 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate ([C4C1Pyr][OTf]). The adsorption geometries of the anions depend on the surface structure, IL coverage, and precoverage of CO. At room temperature, IL multilayers of randomly oriented species grow on top of strongly adsorbed wetting layers. Upon heating, a partial wetting transition induces the coexistence of an IL wetting monolayer film with three-dimensional droplets. Gas-phase CO does not permeate through IL multilayers, while it penetrates the IL wetting monolayer leading to mixed IL/CO films. The partial dewetting transition and the permeability differ drastically with the temperature and IL. Consequently, the morphology of the IL films could be a factor that determines the catalytic behavior of SCILLs to a significant extent.

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Section: Resultsmentioning

confidence: 94%

CO Permeability and Wetting Behavior of Ionic Liquids on Pt(111): An IRAS and PM-IRAS Study from Ultrahigh Vacuum to Ambient Pressure

et al. 2021

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“…Ga. [10][11][12]19 The catalytic reaction in SCALMS occurs exclusively at the liquid metal/gas interface. 10,12,[19][20][21][22][23][24][25] Contrary to conventional SLP catalysis, the reactants and products are insoluble in the liquid phase. In addition, the liquid metal/gas interface is highly dynamic on an atomic scale.…”

Section: Introductionmentioning

confidence: 99%

Capturing spatially resolved kinetic data and coking of Ga–Pt supported catalytically active liquid metal solutions during propane dehydrogenationin situ

et al. 2021

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“…As explanation for this unexpected behaviour, angle‐resolved X‐ray photon spectroscopy (XPS) experiments and molecular dynamics simulations suggest depletion of the topmost layer in Ga‐rich alloys regarding the catalytically active metal, while the layer directly underneath is enriched . The atomic distribution at the liquid catalyst surface is strongly affected by substrates approaching the surface and coming into contact with the active metal atoms –. Dehydrogenation of propane is suggested to require only a single active metal atom .…”

Section: Introductionmentioning

confidence: 99%

“…Dehydrogenation of propane is suggested to require only a single active metal atom . In turn, side reactions requiring a second active site are strongly reduced in the SCALMS approach due to the low probability of neighbouring active metal atoms at the surface of the liquid alloy– in combination with the generally low activation energy for desorption of propene . When compared to the dehydrogenation of butane, propane dehydrogenation (PDH) is expected to be rather vulnerable for the formation of coke.…”

Section: Introductionmentioning

confidence: 99%

Coke Formation during Propane Dehydrogenation over Ga−Rh Supported Catalytically Active Liquid Metal Solutions

et al. 2020

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Supported Catalytically Active Liquid Metal Solutions (SCALMS) were recently described as a new class of heterogeneous catalysts, where the catalytic transformation takes place at the highly dynamic interface of a liquid alloy. Their application in alkane dehydrogenation has been claimed to be superior to classical heterogeneous catalysts, because the single atom nature of Rh dissolved in liquid Ga hinders the formation of significant amounts of coke, e. g. by oligomerisation of carbon fragments and excessive dehydrogenation. In the present study, we investigate the coking behaviour of Ga−Rh SCALMS during dehydrogenation of propane in detail by means of high‐resolution thermogravimetry. We report that the application of Ga−Rh SCALMS indeed limits the formation of coke when compared to the Ga‐free Rh catalyst, in particular when relating coke formation to the catalytic performance. Furthermore, the formed coke has been shown to be highly reactive during temperature programmed oxidation in 21 % O2/He with onset temperatures of approx. 150 °C enabling a regeneration of the Ga−Rh SCALMS system under mild conditions. The activation energy of the oxidation lies in the lower range of values reported for spent cracking catalysts. Monitoring the formation of coke and performance of SCALMS in situ via thermogravimetry coupled with mass spectrometry revealed the continuous formation of coke, which becomes the only process affecting the net weight change after a certain time on stream.

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Pt–Ga Model SCALMS on Modified HOPG: Growth and Adsorption Properties

Cited by 11 publications

References 57 publications

CO Permeability and Wetting Behavior of Ionic Liquids on Pt(111): An IRAS and PM-IRAS Study from Ultrahigh Vacuum to Ambient Pressure

CO Permeability and Wetting Behavior of Ionic Liquids on Pt(111): An IRAS and PM-IRAS Study from Ultrahigh Vacuum to Ambient Pressure

Capturing spatially resolved kinetic data and coking of Ga–Pt supported catalytically active liquid metal solutions during propane dehydrogenationin situ

Coke Formation during Propane Dehydrogenation over Ga−Rh Supported Catalytically Active Liquid Metal Solutions

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