Intermittent temperature-programmed desorption study of perovskites used for catalytic purposes

“…The hydrogen consumption and the possible products formation have been followed by a mass spectrometer (QMS-422 from Baltzers) and a thermal conductivity detector (TCD) previously calibrated with a CuO reference sample. system equipped with a quadrupolar mass spectrometer and an independent pumping system described elsewhere [27][28][29]. The catalyst (100 mg) was placed in a cylindrical quartz sample holder hanged in vacuum by K-type thermocouple wires (50 lm in diameter, spot-welded onto the sample holder) in the centre of a cylindrical quartz reactor.…”

Section: Temperature Programmed Reduction (Tpr-h 2 )mentioning

confidence: 99%

Study of Oxygen Reactivity in La1−x Sr x CoO3−δ Perovskites for Total Oxidation of Toluene

et al. 2012

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The total oxidation of toluene is studied over catalytic systems based on perovskite with general formula AA 0 CoO 3-d (A = La, A 0 = Sr). The systematic and progressive substitution of La 3? by Sr 2? cations in the series (La 1-x Sr x CoO 3-d system) of the perovskites have been studied to determine their influence in the final properties of these mixed oxides and their corresponding reactivity performance for the total oxidation of toluene as a model volatile organic compound with detrimental effects for health and environment. The structure and morphology of the samples before and after reaction have been characterized by XRD, BET and FE-SEM techniques. Additional experiments of temperature programmed desorption of O 2 in vacuum and reduction in H 2 were also performed to identify the main surface oxygen species and the reducibility of the different perovskites. It is remarkable that the La 1-x Sr x CoO 3-d series presents better catalytic performance for the oxidation of toluene, with lower values for the T 50 (temperature of 50 % toluene conversion) than the previously studied LaNi 1-y Co y O 3 series.

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“…The kinetics of oxygen adsorption, oxygen desorption, and changes in oxygen stoichiometry are investigated for a packed‐bed setup by TPD with a carrier gas, using mass spectrometry with a membrane inlet as the detection method. ITPD has been employed in recent studies of perovskites, mainly of mixed conducting lanthanum cobaltites 15. 16 The technique is well‐suited for screening materials for different adsorption sites and for determining the associated desorption activation energies, but it is not suitable for determining the adsorption/desorption order and the number of adsorption sites.…”

Section: Introductionmentioning

confidence: 99%

Oxygen Sorption and Desorption Properties of Selected Lanthanum Manganites and Lanthanum Ferrite Manganites

2015

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Temperature-programmed desorption (TPD) with a carrier gas was used to study the oxygen sorption and desorption properties of oxidation catalysts and solid-oxide fuel cell (SOFC) cathode materials (La(0.85) Sr(0.15)0.95 MnO(3+δ) (LSM) and La(0.60) Sr(0.40) Fe(0.80) Mn(0.20) O(3-δ) (LSFM). The powders were characterized by X-ray diffractometry, atomic force microscopy (AFM), and BET surface adsorption. Sorbed oxygen could be distinguished from oxygen originating from stoichiometry changes. The results indicated that there is one main site for oxygen sorption/desorption. The amount of sorbed oxygen was monitored over time at different temperatures. Furthermore, through data analysis it was shown that the desorption peak associated with oxygen sorption is described well by second-order desorption kinetics. This indicates that oxygen molecules dissociate upon adsorption and that the rate-determining step for the desorption reaction is a recombination of monatomic oxygen. Typical problems with re-adsorption in this kind of TPD setup were revealed to be insignificant by using simulations. Finally, different key parameters of sorption and desorption were determined, such as desorption activation energies, density of sorption sites, and adsorption and desorption reaction order.

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Intermittent temperature-programmed desorption study of perovskites used for catalytic purposes

Cited by 24 publications

References 28 publications

La1−xCexMn1−yCoyO3 perovskite oxides: Preparation, physico-chemical properties and catalytic activity for the reduction of diesel soot

La1−xCexMn1−yCoyO3 perovskite oxides: Preparation, physico-chemical properties and catalytic activity for the reduction of diesel soot

Study of Oxygen Reactivity in La1−x Sr x CoO3−δ Perovskites for Total Oxidation of Toluene

Oxygen Sorption and Desorption Properties of Selected Lanthanum Manganites and Lanthanum Ferrite Manganites

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