La0.6Sr0.4Co0.8Fe0.2O3-delta and Fe2O3/La0.6Sr0.4Co0.8Fe0.2O3-delta powders: XPS characterization

A Sr and Fe doped lanthanum cobaltate was prepared by wet chemistry procedure (Pechini) and compared with a nanocomposite system obtained by depositin iron oxide on the surface of the perovskite by wet impregnation. The investigation of both the systems was carried out by means of XPS

LSCF and Fe2O3/LSCF powders: interaction with methanol

This work focalizes on a nanosized La0.6Sr0.4Co0.8Fe0.2O3 12\u3b4 (LSCF) perovskite and Fe2O3/LSCF nanocomposites. The nanosized LSCF perovskite is obtained by Pechini method and treated at 1173 K; nanocomposite Fe2O3/LSCF powder samples (Fe2O3/LSCF = 1:9 and 1:1 wt.) are obtained by wet impregnation. The reactivity of the obtained samples with respect to pure methanol and to a 1M aqueous solution of methanol, is investigated by means of IR Spectroscopy and Quadrupole Mass Spectrometry (QMS). In presence of pure methanol the main reaction is methanol decomposition with the formation of CO and H2. The activity with respect to this reaction starts to be observed at 573K both for the LSCF perovskite and for the Fe2O3/LSCF nanocomposites and shows an irregular trend as a function of temperature. Steam-reforming reaction is evident at T 65623K when a 1M solution of methanol is used. The reactivity with respect to methanol and to the 1M solution of methanol was also investigated as a function of time: only at 673K the methanol decomposition starts immediately; the waiting time changes as a function of temperature, sample composition and reactive mixture. The steam reforming reaction, in contrast, begins immediately

La0.7Sr0.3CuO3 12\u3b4: An Interesting Catalyst for Methanol and Ethanol Treatment

The reactivity of La0.7Sr0.3CuO3-\u3b4 with methanol and ethanol was investigated in oxidation and steam reforming. The conversion is higher in the oxidation reactions (about 100 %) than in steam reforming (78% for methanol, 23% for ethanol). Significant amounts of hydrogen are observed during methanol steam reforming. Acetaldehyde forms with ethanol

Effect of the preparation procedure on the surface properties of nanosized ceria powders

Nanosized cerium (IV) oxide powders were synthesized using three different preparation procedures: 1 precipitation from a basic solution of cerium nitrate containing H2O2 at 273 K; 2 Marcilly method, and 3 microemulsion method. In this work the influence of the preparation procedure on the surface properties is studied by means of XPS. Besides the wide scan spectrum, detailed spectra for the Ce 3d, Ce 4d, O 1s and C 1s regions and relative data are presented and discussed

Mixed Mangesium and Zinc oxides by co-precipitation

Two Zinc-Magnesium Oxide powders were prepared by means of a sol-gel method based on the mixing of nitrates of Mg and Zn, followed by complexation with citric acid. The samples are characterized by a nominal (i.e. calculated from the weighted amount of precursors) Zn/Mg atomic ratio of 0.01 (specimen 1, Accession #1232), and 0.5 (specimen 2, Accession #1233). The surface properties and the influence of the Zn/Mg atomic ratio are investigated by means of XPS (using a standard Al Ka). Besides the wide scan spectra, detailed spectra for the Mg 1s, Zn 2p3/2 and O 1s regions and related data are presented and discussed. XP analysis confirms the presence of Mg (II) and Zn (II). The XPS Zn/Mg atomic ratio is always lower than the nominal one; this is particularly evident in specimen 1 (Accession #1232) thus suggesting a certain surface segregation of magnesium. The O/(Mg + Zn) atomic ratio is higher than the nominal one and decreases with increasing the Zn/Mg atomic ratio (from 1.5 for [Zn/Mg]nom=0.01 to 1.3 for [Zn/Mg]nom=0.5)

Steam reforming and oxidative steam reforming of methanol and ethanol: The behaviour of LaCo0.7Cu0.3O3

LaCo0.7Cu0.3O3 perovskite powder was prepared by means of the citrate method and treated at different temperatures from 873 to 1323 K. The samples were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), temperature programmed reduction (TPR), temperature programmed desorption (TPD, O2-TPD), and scanning electron microscopy (SEM); the BET specific surface area was also determined. The reactivity of the perovskite with methanol and ethanol was investigated under steam reforming and oxidative steam reforming conditions and correlated to its chemical and structural properties. Different oxygen/alcohol molar ratios were used to study the influence of oxygen on catalytic activity and products distribution. LaCo0.7Cu0.3O3 begins to be active in alcohol steam reforming at about 523 K. The catalyst calcined at 873K shows the higher conversion in methanol steam reforming. Ethanol steam reforming conversion, in contrast, is rather low and not significantly affected by the catalyst calcination temperature. The conversions increase when oxygen is present reaching 93% for methanol and 78% for ethanol. Beside the steam reforming and oxidative steam reforming, other secondary reaction paths occur: methanol decomposition and ethanol dehydrogenation