Search results for " TPR"

showing 4 items of 4 documents

Oxidative dehydrogenation of ethane over NiO–CeO2 mixed oxides catalysts

2012

[EN] In this paper we present the synthesis, characterization and catalytic behaviour in the oxidative dehydrogenation of ethane of NiO-CeO2 mixed oxides. The addition of cerium oxide to NiO strongly modifies its catalytic performance, although the changes in the catalytic behaviour depend on the catalyst composition. The incorporation of low amounts of cerium oxide to NiO multiplies the productivity to ethylene in the oxidative dehydrogenation of ethane by a factor of ca. 7, which is the result of an increase in both catalytic activity and selectivity to ethylene. The enhanced activity has been related to the remarkable increase of the surface area of catalyst and the low crystal sizes of …

Cerium oxideEthyleneCatalyst characterization (XPS TPR XRD Raman FTIR of adsorbed CO oxygen isotopic-exchange)Inorganic chemistryNon-blocking I/Ochemistry.chemical_elementCerium oxideGeneral ChemistryCatalysisCatalysisCerium(IV) oxide–cerium(III) oxide cycleEthylenechemistry.chemical_compoundCeriumchemistryDehydrogenationOxidative dehydrogenation of ethaneNickel oxideSelectivityCatalysis Today
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Palladium local structure of La1-xSrxCo1-yFey-0.03Pd0.03O3-δperovskites synthesized using a one pot citrate method

2014

Nanostructured La1-xSrxCo1-yFey-0.03Pd0.03O3-δ(LSCF-Pd) perovskites with fixed La-Sr composition (x = 0.4) and two different Fe contents (y = 0.2 and 0.8) were successfully synthesized using a one pot citrate method starting from nitrates of the metal cations. Pd-free La1-xSrxCo1-yFeyO3-δ(LSCF) systems were prepared for comparison. LSCF powders were calcined at 1300 °C and characterized by XRD and Rietveld refinement, EXAFS, XPS, TPR analyses. Promotion of La0.6Sr0.4Co0.8Fe0.2O3-δand of La0.6Sr0.4Co0.2Fe0.8O3-δby incorporation of palladium was evidenced by solving the local environment of Pd using EXAFS spectroscopy. XPS analyses, in agreement with TPR measurements, demonstrated an inc…

Physics and Astronomy (all); Physical and Theoretical ChemistryLSCF perovskyte EXAFS XRD TPRMaterials scienceExtended X-ray absorption fine structureRietveld refinementInorganic chemistryGeneral Physics and Astronomychemistry.chemical_elementIonic bondinglaw.inventionMetalPhysics and Astronomy (all)X-ray photoelectron spectroscopychemistrylawvisual_artvisual_art.visual_art_mediumCalcinationPhysical and Theoretical ChemistryPalladiumPerovskite (structure)
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Structural and morphological investigation of a cobalt catalyst supported on alumina-baria: effects of redox treatments on the activity in the NO red…

2004

Abstract Temperature-programmed reduction (TPR) and temperature-programmed oxidation (TPO) have been used to study the various cobalt species formed in a cobalt catalyst (Co 1 wt.%) supported on alumina-baria, with composition Al2O3(80 wt.%)–BaO (20 wt.%). The catalyst was synthesized by incipient-wetness impregnation of the support with a water solution of cobalt acetylacetonate and calcined at 550 °C for 5 h. In order to investigate the structure and morphology of the sample, XRD, BET and SEM analyses were performed. Depending on the temperature and nature of pre-treatment (reductive or oxidative) different Co species (Co3O4, Co3+, surface Co2+, CoAl2O4) were formed. Activity tests in the…

Process Chemistry and TechnologyInorganic chemistrychemistry.chemical_elementDecompositionNitrogenRedoxCatalysisCatalysislaw.inventionCobalt oxide Alumina-baria TPR/TPO cycleschemistrylawCalcinationSelectivityCobalt oxideCobaltGeneral Environmental ScienceApplied Catalysis B: Environmental
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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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