Search results for "Small Angle X-ray Spectroscopy"

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Formation and Growth of Pd Nanoparticles Inside a Highly Cross-Linked Polystyrene Support: Role of the Reducing Agent

2014

Simultaneous time-resolved SAXS and XANES techniques were employed to follow in situ the formation of Pd nanoparticles in a porous polystyrene support, using palladium acetate as a precursor and gaseous H2 or CO as reducing agents. These results, in conjunction with data obtained by diffuse reflectance UV–vis and DRIFT spectroscopy and TEM measurements, allowed unraveling of the different roles played by gaseous H2 and CO in the formation of the Pd nanoparticles. In particular, it was found that the reducing agent affects (i) the reduction rate (which is faster in the presence of CO) and (ii) the properties of the hosted nanoparticles, in terms of size (bigger with CO), morphology (spherica…

Materials scienceExtended X-ray absorption fine structureReducing agentSmall-angle X-ray scatteringchemistry.chemical_elementNanoparticlePd nanoparticles; SAXS; EXAFSSAXSXANESSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsCrystallographychemistry.chemical_compoundEXAFSGeneral EnergyPd nanoparticleschemistryChemical engineeringPalladium nanoparticles time-resolved X-ray Absorption Spectroscopy Small Angle X-ray Spectroscopy Transmission Electron MicroscopyDiffuse reflectionPolystyrenePhysical and Theoretical ChemistryPalladium
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Effect of Pre-Reduction on the Properties and the Catalytic Activity of Pd/Carbon Catalysts: A Comparison with Pd/Al2O3

2013

The effect of pre-reduction in solution with chemical reagents on the catalytic performance and catalyst properties of Pd/carbon catalysts was systematically investigated with a multitechnique approach. The results are critically discussed in comparison to those recently obtained on analogous Pd/alumina catalysts. It was proved that the Pd phase on the carbon surface is characterized by a high mobility, opposite to what occurs on alumina. As a result, the Pd particles on carbon aggregate together during pre-reduction, with a consequent decrease in available metal surface. Pd particles remain aggregated also in reaction conditions; the decreased Pd dispersion negatively affects the catalyst …

characterization techniqueCO chemisorptionInorganic chemistryPd-based catalystchemistry.chemical_elementTPRHeterogeneous catalysisPd/CarbonCatalysisCatalysisMetalCharacterization techniquesCatalyst pre-reductionTemperature-programmed reductionX-ray absorption spectroscopymetal nanoparticlein situPd-based catalystsPd/aluminaSAXSGeneral ChemistryXANESSmall Angle X-ray ScatteringX-ray Absorption SpectroscopyPd/Carbon; Pd/alumina; metal nanoparticle; catalysis; Catalyst pre-reduction; in situ; SAXS; XANES; Pd-based catalysts; heterogeneous catalysis; Characterization techniques; Temperature-programmed reduction; TPR; CO chemisorption; TEM; X-ray absorption spectroscopy; Small Angle X-ray Scatteringheterogeneous catalysischemistryReagentvisual_arttemperature-programmed reductionvisual_art.visual_art_mediumTEMheterogeneous catalysiSmall Angle X-ray SpectroscopyDispersion (chemistry)Carbon
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