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51.
Surman J. Majda D. Rafalska-Łasocha A. Kuśtrowski P. Chmielarz L. Dziembaj R. 《Journal of Thermal Analysis and Calorimetry》2001,65(2):445-450
K-promoted hematite catalysts for ethylbenzene dehydrogenation were studied by thermal analysis (TG/DTG) and high-temperature
XRD. The formation of potassium ferrite (K2Fe2O4), considered to be a catalytically active phase, was observed during calcination of the Ce-promoted catalysts. A linear correlation
of the catalytic activity and the temperature of potassium ferrites formation was found.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
52.
Riham Michelle Morcos Alexandra Navrotsky 《Journal of Thermal Analysis and Calorimetry》2009,96(2):353-361
Differential scanning and high temperature reaction calorimetry have been used to characterize a series of natural iron ore
and flux samples commonly used during iron ore sintering. Most iron ore samples were shown to contain measurable quantities
of goethite, with a characteristic dehydration peak in DSC and TG between 200 and 400°C. At higher temperatures, all samples
decomposed to produce magnetite with an accompanying mass loss in the TG profile due to the evolution of oxygen.
High temperature reaction calorimetry has been used to measure the heat of solution of the ore in the melt formed during iron
ore sintering. The dehydration and calcination of iron ore and flux samples was also examined using high-temperature reaction
calorimetry. The results support the DSC/TG findings. 相似文献
53.
54.
This report is about the X-ray diffraction and Mössbauer studies of three impactite samples denominated PMe-8, PMe-9 and PMe-11 from Huamalies Province in Huánuco Region, Peru. When terrestrial rocks are submitted to pressures higher than 60 GP, the majority is completely melted, forming a kind of glass called impactites. X-ray diffraction indicates the presence of quartz as the principal mineralogical phase in all samples. The 57Fe Mössbauer spectra at room temperature of samples PMe-8 and PMe-9 show broadened spectra that were fitted using a distribution model. The most probable field of the magnetic component is 34 T, corresponding to the presence of small particles of goethite, confirmed by the 4.2 K spectrum. For the sample PMe-11, the MS showed the presence of well crystallized hematite. 相似文献
55.
Fire-induced mineral transformations have been investigated in composite mineral grains separated from the coarse sand fractions (400–2,000 μm) from Ultisols developed in the Chittagong Hill Tracts (Bangladesh). Magnetic and colour based separation (into light brown, dark red, and magnetic, dark red classes) were used to select the grains that were studied by Mössbauer spectroscopy. Aluminium substituted goethite (α-FeOOH) dominates the light brown particles. Fire transform the goethite into a poorly crystalline hematite (α-Fe2O3) dominating in the dark red particles. In the dark red, magnetic grains a recrystallized hematite dominates, but small amounts of maghemite (γ-Fe2O3) are also present. The latter is indicated by comparing the line intensities in spectra measurement with and without an external magnetic field. 相似文献
56.
Oliveira A. C. Marchetti G. S. Carmo Rangel M. 《Journal of Thermal Analysis and Calorimetry》2003,73(1):233-240
The effect of the iron precursor on the thermal decomposition of iron oxyhydroxides was studied by DSC, DTA and TG in this work. Samples were prepared from iron nitrate, iron sulfate and iron chloride and the thermal curves obtained were analyzed by specific area measurements, X-ray diffraction and Mössbauer spectroscopy. It was found that the iron oxyhydroxide precursors affect the temperatures of the hematite formation as well as the textural properties of the final hematite producing particles with different diameters as following: iron sulfate (3.3 nm)相似文献
57.
Alcinéia Conceição Oliveira Antoninho Valentini Paulo Sérgio Santana Nobre Maria do Carmo Rangel 《Reaction Kinetics and Catalysis Letters》2002,75(1):135-140
The effect of iron nitrate, sulfate and chloride on the catalytic properties of hematite toward ethylbenzene dehydrogenation has been studied. Iron nitrate has been the best precursor to prepare the catalysts. 相似文献
58.
C. Sikalidis T. Zorba K. Chrissafis K.M. Paraskevopoulos 《Journal of Thermal Analysis and Calorimetry》2006,86(2):411-415
Phase changes of iron containing solid wastes from steel mill pickling
lines after thermal treatments were investigated aiming the determination
of the appropriate conditions for its transformation to be useful for industrial
raw materials. Above 275°C, the thermally treated wastes contain a mixture
of α-Fe2O3 (hematite)
and γ-Fe2O3 (maghemite)
in different proportions, depending on the maximum heating temperature of
the thermal treatment. Increasing the maximum temperature the maghemite participation
is decreased through its transformation to hematite. Above 850°C hematite
is the main constituent, suggesting that thermal treatment of the wastes in
this temperature will give a product that could be used as red iron pigment. 相似文献
59.
M.G. Ferreira da Silva M.A. Valente 《Journal of Sol-Gel Science and Technology》2003,26(1-3):1091-1096
Aluminosilicate pellets containing 10 mol% of Fe2O3, prepared by the sol-gel method, have been investigated. Electrical conductivity, dielectric constant, X-ray diffraction, scanning electron microscopy and electron paramagnetic resonance have been used to characterize the evolution of the samples with the heat-treatment temperature and atmospheric conditions. Results show that iron is present in the air heat-treated samples as Fe3+, goethite and hematite particles. Metallic iron and magnetite were identified in the samples heat-treated under reducing conditions. The d.c. conductivity decreases with increasing heat-treatment temperature of the samples indicating a variation, with the temperature, of the electrical free charges. However, in the case of the dielectric constant the samples heat-treated in air and under reducing conditions do not present the same behaviour. This variation was related with the microstructural evolution of the samples. 相似文献
60.
Joseína Moutinho Tavares de Souza Maria do Carmo Rangel 《Reaction Kinetics and Catalysis Letters》2004,83(1):93-98
Aluminium-rich hematite was found to catalyze the water gas shift reaction but there is a compromise between the increase
in specific surface area and the intrinsic activity.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献