1,721,069 research outputs found
Perovskite-based catalysts and electrocatalysts A stable framework for the design of novel innovative materials for sustainable development: from abatement of pollutants to energy conversion and storage
No full textHeterogeneous catalysis in the sustainable development: from pollutants’ abatement energy conversion and storage from surface science to industrial application.
No full textOn the effects of doping on the catalytic performance of (La,Sr)coo 3 . A DFT study of CO oxidation
Full text linkThe effects of modifying the composition of LaCoO3 on the catalytic activity are predicted by density functional calculations. Partially replacing La by Sr ions has benefical effects, causing a lowering of the formation energy of O vacancies. In contrast to that, doping at the Co site is less effective, as only 3d impurities heavier than Co are able to stabilize vacancies at high concentrations. The comparison of the energy profiles for CO oxidation of undoped and of Ni-, Cu-m and Zn-doped (La,Sr)CoO3(100) surface shows that Cu is most effective. However, the effects are less spectacular than in the SrTiO3 case, due to the different energetics for the formation of oxygen vacancies in the two hosts
Pulsed reactivity on LaCoO3-based perovskites: A comprehensive approach to elucidate the CO oxidation mechanism and the effect of dopants
No full textIn this contribution we focus on three lanthanum cobaltate perovskites: undoped, Sr-doped, and Cudoped to investigate the effect of doping on reactivity. The catalysts are prepared by a citric acid route and characterized by X-ray diffraction, temperature programmed desorption, energy dispersive X-ray analysis, and BET specific surface area measurement. A pulsed reactivity experiment has been set up in order to investigate the catalytic oxidation reaction of carbon monoxide (CO). Within a single experiment, this analysis allowed evaluation of the oxygen storage capacity (OSC) and derivation of kinetic parameters to compare the behavior of the different catalysts. Compared to the traditional steady-state experiments, a clear insight into the reaction mechanism is obtained, providing a deeper mechanistic view on the role of the perovskite oxide. An active role of the oxygen species of the catalysts has been demonstrated, with the temperature of 350 degrees C representing a threshold for the activation of bulk oxygen mobility. The effect of doping has been discussed in terms of enhancement of the reducibility of the perovskite oxides, resulting in lower activation energies for the catalytic oxidation of CO
Perovskites as Alternatives to Noble Metals in Automotive Exhaust Abatement: Activation of Oxygen on LaCrO 3 and LaMnO 3
No full textIn this contribution, perovskitic materials have been tested as substitutes of noble metals in automotive exhaust abatement devices. LaMnO3 and LaCrO3 were the chosen materials. Samples were characterized by means of X-ray diffraction, scanning electron microscopy, BET surface area, temperature programmed reduction and X-ray photoelectron spectroscopy. Reactions tested have been soot oxidation by 10% O2 and 0.5% NO and stoichiometric 1% NO reduction by 1% CO. LaMnO3 has proved to be a good catalyst for oxidation reactions, whereas LaCrO3 is more suitable for reduction reactions. TPR and XPS analysis have shown a greater oxygen exchange capability in LaMnO3 than in LaCrO3, which is less reducible and strongly bonds adsorbed oxygen. Substitution of 20% La in the A-site of the perovskitic lattice with K has increased activity of both catalysts. In the case of LaCrO3, however, this has lead to a slower reaction course. NO reduction test clearly indicates that Cr-containing perovskite is more suitable for reduction reactions, whereas Mn-based materials are a good choice for oxidative applications. This can relate to superficial oxygen properties and bulk oxygen mobility, as shown by XPS and TPR results
Improving catalytic and electro-catalytic functionality in perovskites. Can noble metals be avoided?
No full textNext generation solid oxide cells: building advanced functionality through doping and nanocomposition
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Synthesis and characterization of Ca2Fe1.95Mg0.05O5: innovative low cost material for Reversible Solid Oxide Cell
No full textThree and Four Way Catalysts: pollution abatement with perovskites and perovskite-based nanocomposites
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