1,721,001 research outputs found
La1−xSrxCo1−yFeyO3− perovskites: Preparation, Characterization and Solar Photocatalytic Activity in gas-solid regime
No full textLaCoO3 perovskites substituted by Sr at the A site and/or by Fe at the B site have been prepared by the
citrate method. Characterizations by several techniques, such as specific surface area (BET method), XRD,
TPR, SEM,UV–vis in DRS mode, XPS and TGA analyses, have been performed.
The sopreparedLa1−xSrxCo1−yFeyO3−d perovskites are semiconductor materials showing bandgap
energy valuesfrom1.9to3.2eV.Theydisplayedsolarphotocatalyticactivityforthe2-propanol degradation in gas–solid regime. The photocatalytic results suggest that the perovskites containing Fe are less active and the activity decreases by increasing the Fe content, however the presence of iron avoids the catalyst deactivation. The best photocatalytic activity in the 2-propanol degradation was found for the sample La0.6Sr0.4CoO3−d
Cerium effect on the phase structure, phase stability and redox properties of Ce-doped strontium ferrates
No full textFROM INTERCONNECTORS TO ANODE MATERIALS FOR IT-SOFCs:THE ROLE OF IRON IN La1-xSrxCr1-yFeyO3-δ
No full textAu/CeO2-SBA-15 catalysts for CO oxidation: effect of ceria loading on physic-chemical properties and catalytic performances
No full textIn this work gold catalysts supported over SBA-15 with different CeO2 loadings (5–30 wt%) were prepared,
characterized by N2 physisorption analyses, SAXS, XRD, STEM and XPS techniques and their catalytic
performances were evaluated in the CO oxidation, chosen as reaction test. Over a selected catalyst,
Au/CeO2(20 wt%)-SBA-15, the effect of CO2 and of the mixture (CO2 + H2O) on the CO conversion to CO2
was also evaluated.
Characterizations by SAXS, XRD, STEM and XPS were carried out on selected spent catalysts after CO
oxidation.
The results were discussed in terms of relationship between morphological, structural, electronic and
catalytic properties as a function of the ceria loading. The CO oxidation activity was strongly affected by
gold particle size and gold/ceria interface as well. For gold catalysts supported on ceria-doped SBA-15,
the oxygen vacancies in ceria likely act as nucleation sites for gold anchoring and stabilization against
sintering. The optimum of the catalytic performances was found for 20 wt% ceria loading, likely due to
the optimum synergistic interaction between highly dispersed defective ceria oxide and nanosized gold
Co3O4/CeO2 and Co3O4/CeO2-ZrO2 composite catalysts for methane combustion: Correlation between morphology reduction properties and catalytic activity
No full textExploring Solvent-free Citrate-Nitrate Auto-Combustion for the Synthesis of SOFC Electrocatalysts
No full textStudies on Catalytic and catalytic photo-assisted propene hydration in the presence of H3PW12O40 supported on different oxides
No full textStructural and morphological investigation of a cobalt catalyst supported on alumina-baria: effects of redox treatments on the activity in the NO reduction by CO
No full textTemperature-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 reduction of NO by CO were carried out in order to investigate the effectiveness of the catalyst depending on the redox pre-treatment.
Highly dispersed Co3O4 particles, formed after a TPR up to 1100 °C and successive TPO up to 550 °C are active for the NO reduction at low temperature, N2O being the major product at 250 °C, while N2 formation was favored at temperature higher than 400 °C.
The as prepared sample, calcined at 550 °C for 5 h, exhibits significant activity only at temperature > 400 °C, giving selective formation of N2.
The nature of the active species in the supported catalyst was confirmed by studying the CO + NO reaction and NO decomposition over Co3O4 and CoO oxides as reference materials.
On Co3O4 the NO reduction occurs with different selectivity to N2O/N2, depending on the reaction temperature: at low temperature only N2O was detected, whereas at temperature >350 °C also N2 formation was observed. Then at temperature ≥450 °C only the reaction NO→N2 takes place. Over CoO the reaction starts at ∼400 °C and N2 is the only nitrogen product detected in the whole range of temperature investigated. Hundred percent of NO conversion into N2 is reached at 600 °C
Structural and morphological properties of Co-La catalysts supported on alumina/lanthana for hydrocarbons oxidation
No full textTwo Al2O3(24wt%)–La2O3(76wt%) supported Co–La oxides with Co loading 4wt% and different La content (1 and 9wt%) were
prepared by co-impregnation of the support, the aluminum–lanthanum oxide, with cobalt and lanthanum nitrates in aqueous solution
and successive calcination at 800C for 4h. The alumina–lanthana was synthesized by the sol–gel method.
The samples were characterized by X-ray diffraction (XRD) and Rietveld refinement in order to identify the crystalline phases
and their relative weight. H2-TPR (Temperature Programmed Reduction) experiments were recorded with the aim to identify the
different Co phases present. Co3O4 and LaCoO3 were formed for La loading of 1%, whereas at higher La loading (9%) LaCoO3
and La2O3 oxide prevailed. In both catalysts LaAlO3 phase was also detected.
As observed by BET and SEM characterizations, the morphology of the two catalysts was somewhat affected by La:Co atomic
ratio and differed dramatically from those of the reference bulk oxides, Co3O4 and the mixed phase LaCoO3/La2O3. Activity tests in
C3H6 and CH4 combustion were carried out in order to discriminate the catalytic properties of different phases formed (Co3O4,
LaCoO3, La2O3, LaAlO3)
“Direct synthesis of methyl isobutyl ketone in gas-phase reaction over palladium-loaded hydroxyapatite”
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