X-ray absorption spectroscopy and heterogeneous catalysis: Performances at the SOLEIL's SAMBA beamline

Fontaine, Camille La; Barthe, Laurent; Rochet, Amélie; Briois, Valérie

doi:10.1016/j.cattod.2012.09.032

Cited by 79 publications

(67 citation statements)

References 39 publications

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“…Fast in situ acquisitions were obtained using aQ uick-XAS monochromator equipped with ac hannel-cut Si(111)c rystal the oscillating movement of which was set to acquire one spectrum every 0.5 s. [47] The powdered sample was placed into ad edicated in situ cell, [48] positioned between two Ohken ionization chambers filled with nitrogen, for detection of the incident and transmitted X-rays. This cell enabled catalyst treatments to be performed under controlled conditions of temperature and gas flow.…”

Section: Characterization Of the Catalystsmentioning

confidence: 99%

Correlation between Structural and Catalytic Properties of Copper Supported on Porous Alumina for the Ethanol Dehydrogenation Reaction

et al. 2015

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Carbon nanofibers (CNFs) were functionalized with aryl sulfonic acid groups using in situ diazonium coupling. The use of diazonium coupling yielded an acidic carbon material, in which the introduced acidic groups are readily accessible to the triglyceride substrate. The material is an efficient catalyst for the transesterification of triolein and methanol, outperforming conventional sulfonated carbons in both stability and activity per acid site. Upon comparing CNFs with varying degrees of functionalization, a linear correlation between sulfonic acid sites and catalytic performance was found.

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Section: Characterization Of the Catalystsmentioning

confidence: 99%

Correlation between Structural and Catalytic Properties of Copper Supported on Porous Alumina for the Ethanol Dehydrogenation Reaction

et al. 2015

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“…Because we used Pd mirrors to reject harmonics, the baseline was checked to ensure the absence of a residual Pd signal, owing to nonlinearity in the detectors. The experiments were conducted using the transmission and fluorescence cell fully described in [47]. 8 mg of catalyst, diluted 1:10 by weight with BN, and a total gas flow rate of 12 mL min À1 (0.5 % CH 4 , 2.0 % O 2 , 15.0 % H 2 O if needed, and N 2 balance) were used for Ce L III edge experiments.…”

Section: Operando Xafs Measurementsmentioning

confidence: 99%

Methane Catalytic Combustion over Hierarchical Pd@CeO₂/Si‐Al₂O₃: Effect of the Presence of Water

et al. 2014

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The influence of water vapor on methane catalytic combustion was studied over a Pd@CeO2/Si‐Al2O3 catalyst, carefully designed to maximize Pd‐CeO2 interaction and prevent metal sintering and compared to a conventional impregnated catalyst with identical chemical composition. Although the nanostructured Pd@CeO2/Si‐Al2O3 catalyst is thermally stable, the addition of water to the reaction feed leads to a transient deactivation at low temperatures, consistent with the well documented competitive adsorption. In addition to this, the hierarchically structured catalyst exhibits an additional severe deactivation after methane oxidation in the presence of water vapor at 600 °C that can be reversed only by heating the catalyst above 700 °C. The presence of water in the reaction feed deactivates the conventional impregnated catalyst less severely and the activity largely returns upon water removal. Catalytic FTIR and CO‐chemisorption data indicate that this severe deactivation process in the hierarchical catalyst is due to the formation of stable OH groups on the surface of the ceria nanoparticles. These hydroxyl groups are suggested to significantly inhibit the oxygen spillover from the CeO2 nanoparticles to Pd, preventing its efficient re‐oxidation, as observed by operando X‐ray absorption near edge spectroscopy (XANES) experiments. At the same time, their presence can contribute to limit the gas phase accessibility of Pd, as indicated by the decrease of CO chemisorption capability. The presence of hydroxyls plays a minor role on the deactivation of the conventional catalyst at 600 °C.

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“…Bulk Pd and Rh were also measured and used as references. The powder samples were placed inside the Lytle-type cell available on the beam line (Fontaine et al, 2013). The sample cell was connected to a gas distribution system that allows careful control of the gas mixture and the flow at atmospheric pressure.…”

Section: X-ray Absorption Spectroscopymentioning

confidence: 99%

Experimental Challenges in Studying Hydrogen Absorption in Ultrasmall Metal Nanoparticles

et al. 2016

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Recent advances on synthesis, characterization, and hydrogen absorption properties of ultrasmall metal nanoparticles (defined here as objects with average size ≤3 nm) are briefly reviewed in the first part of this work. The experimental challenges encountered in performing accurate measurements of hydrogen absorption in Mg-and noble metal-based ultrasmall nanoparticles are addressed. The second part of this work reports original results obtained for ultrasmall bulk-immiscible Pd-Rh nanoparticles. Carbonsupported Pd-Rh nanoalloys in the whole binary chemical composition range have been successfully prepared by liquid impregnation method followed by reduction at 300°C. EXAFS investigations suggested that the local structure of these nanoalloys is partially segregated into Rh-rich core and Pd-rich surface coexisting within the same nanoparticles. Downsizing to ultrasmall dimensions completely suppresses the hydride formation in Pd-rich nanoalloys at ambient conditions, contrary to bulk and larger nanosized (5-6 nm) counterparts. The ultrasmall Pd90Rh10 nanoalloy can absorb hydrogen-forming solid solutions under these conditions, as suggested by in situ X-ray diffraction (XRD). Apart from this composition, common laboratory techniques, such as in situ XRD, DSC, and PCI, failed to clarify the hydrogen interaction mechanism: either adsorption on developed surfaces or both adsorption and absorption with formation of solid solutions. Concluding insights were brought by in situ EXAFS experiments at synchrotron: ultrasmall Pd75Rh25 and Pd50Rh50 nanoalloys absorb hydrogen-forming solid solutions at ambient conditions. Moreover, the hydrogen solubility in these solid solutions is higher with increasing Pd content, and this trend can be understood in terms of hydrogen preferential occupation in the Pd-rich regions, as suggested by in situ EXAFS. The Rh-rich nanoalloys (Pd25Rh75 and Pd10Rh90) only adsorb hydrogen on the developed surface of ultrasmall nanoparticles. In summary, in situ characterization techniques carried out at large-scale facilities are unique and powerful tools for in-depth investigation of hydrogen interaction with ultrasmall nanoparticles at local level.

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X-ray absorption spectroscopy and heterogeneous catalysis: Performances at the SOLEIL's SAMBA beamline

Cited by 79 publications

References 39 publications

Correlation between Structural and Catalytic Properties of Copper Supported on Porous Alumina for the Ethanol Dehydrogenation Reaction

Correlation between Structural and Catalytic Properties of Copper Supported on Porous Alumina for the Ethanol Dehydrogenation Reaction

Methane Catalytic Combustion over Hierarchical Pd@CeO₂/Si‐Al₂O₃: Effect of the Presence of Water

Experimental Challenges in Studying Hydrogen Absorption in Ultrasmall Metal Nanoparticles

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X-ray absorption spectroscopy and heterogeneous catalysis: Performances at the SOLEIL's SAMBA beamline

Cited by 79 publications

References 39 publications

Correlation between Structural and Catalytic Properties of Copper Supported on Porous Alumina for the Ethanol Dehydrogenation Reaction

Correlation between Structural and Catalytic Properties of Copper Supported on Porous Alumina for the Ethanol Dehydrogenation Reaction

Methane Catalytic Combustion over Hierarchical Pd@CeO2/Si‐Al2O3: Effect of the Presence of Water

Experimental Challenges in Studying Hydrogen Absorption in Ultrasmall Metal Nanoparticles

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Methane Catalytic Combustion over Hierarchical Pd@CeO₂/Si‐Al₂O₃: Effect of the Presence of Water