Spectrum baseline artefacts and correction of gas-phase species signal during diffuse reflectance FT-IR analyses of catalysts at variable temperatures

Paredes-Nunez, Anaëlle; Jbir, Imen; Bianchi, Daniel; Meunier, Frédéric

doi:10.1016/j.apcata.2015.01.042

Cited by 50 publications

(38 citation statements)

References 44 publications

(181 reference statements)

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“…Based on these results, the low-index (100) surface was built from the optimized -Sn (body-centered tetragonal, BCT) bulk structure. The calculated equilibrium lattice constants (a, b = 5.94 Å, c = 3.21 Å) were found to be slightly overestimated compared to the experimental values (a = b = 5.83 Å, c = 3.18 Å at 298.15 K) [44] , but in good agreement with reported theoretical results [27,31,34]…”

Section: Ii2 Theoretical Detailssupporting

confidence: 84%

Combined DRIFTS and DFT Study of CO Adsorption and Segregation Modes in Pt–Sn Nanoalloys

et al. 2020

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This contribution aims at rationalizing the observations made by in situ IR spectroscopy during CO adsorption over 1.8 nm Pt-Sn nanoparticles by Density Functional Theory (DFT) calculations and describing the environment and electronic properties of surface Pt atoms modified by Sn. Pt surface enrichment upon CO exposure was observed by DRIFTS (diffuse reflectance FT-IR spectroscopy) and rationalized by the theoretical calculations, which also indicated that isolated Pt was favored over Pt pairing in a Sn-rich alloy. DFT frequency calculations allowing the fine assignment of vibrational CO spectra. The results show gradual decay of the linear carbonyl wavenumber from plain Pt (2075 cm-1), through a Sn-poor Pt-Sn (2054 cm-1) and down to a Sn-rich Pt-Sn nanoparticles (2039 cm-1). This decay is accompanied by a weakening of Pt-CO bonds, which confirm the ability of Sn to prevent CO poisoning of Pt when present in a nanoalloy. Moreover, electronic structure analyses evidence a preponderant charge transfer from Sn to Pt atoms, which explains the weakening of both the Pt-CO bond and the CO bond through back-donation to antibonding molecular orbitals. A weaker CO bond would favor CO dissociation and the formation of Pt and SnOx ensembles, which is consistent with DRIFTS data recorded at low temperatures.

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Section: Ii2 Theoretical Detailssupporting

confidence: 84%

Combined DRIFTS and DFT Study of CO Adsorption and Segregation Modes in Pt–Sn Nanoalloys

et al. 2020

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“…The contribution of gas‐phase CO on the DRIFTS spectra could be precisely subtracted according to the method reported elsewhere, to facilitate the analysis of adsorbed CO bands. The signal obtained at pseudo‐steady‐state (that is, >20 h on stream) of the Sn‐modified samples was compared to that of the Co/alumina (Figure ).…”

Section: Specific Surface Area Metal Loading and Cobalt Dispersion mentioning

confidence: 97%

CO Hydrogenation on Cobalt‐Based Catalysts: Tin Poisoning Unravels CO in Hollow Sites as a Main Surface Intermediate

et al. 2017

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Site poisoning is a powerful method to unravel the nature of active sites or reaction intermediates. The nature of the intermediates involved in the hydrogenation of CO was unraveled by poisoning alumina‐supported cobalt catalysts with various concentrations of tin. The rate of formation of the main reaction products (methane and propylene) was found to be proportional to the concentration of multi‐bonded CO, likely located in hollow sites. The specific rate of decomposition of these species was sufficient to account for the formation of the main products. These hollow‐CO are proposed to be main reaction intermediates in the hydrogenation of CO under the reaction conditions used here, while linear CO are mostly spectators.

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“…The pseudo-absorbance gives a better linear representation of the band intensity against surface coverage than that given by the Kubelka-Munk function for strongly absorbing media such as those based on metals supported on oxides [28,29]. The preparation of the catalyst sample for the quantitative exploitation of the IR spectra in diffuse reflectance mode was similar to previous studies [29,30].…”

Section: Diffuse Reflectance Modementioning

confidence: 98%

Heat of adsorption of CO on EUROPT-1 using the AEIR method: Effect of analysis parameters, water and sample mode

Jbir

Paredes-Nunez

Khaddar-Zine

et al. 2015

Applied Catalysis A: General

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Spectrum baseline artefacts and correction of gas-phase species signal during diffuse reflectance FT-IR analyses of catalysts at variable temperatures

Cited by 50 publications

References 44 publications

Combined DRIFTS and DFT Study of CO Adsorption and Segregation Modes in Pt–Sn Nanoalloys

Combined DRIFTS and DFT Study of CO Adsorption and Segregation Modes in Pt–Sn Nanoalloys

CO Hydrogenation on Cobalt‐Based Catalysts: Tin Poisoning Unravels CO in Hollow Sites as a Main Surface Intermediate

Heat of adsorption of CO on EUROPT-1 using the AEIR method: Effect of analysis parameters, water and sample mode

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