Thermodynamic analysis of chromium reduction from oxide Cr<sub>2</sub>O<sub>3</sub>

Thermodynamic analysis of chromium reduction from its oxide in gas phase Н2 – Н2О – СО – СО2 in contact with carbon was performed. Oxidation potential (pO2 ) was determined by two nomograms in the coordinates and taking into account condition normalizations xH2O + xH2 + xCO2+ xCO = 1. In calculations, possible parameters of reduction of chromium from Cr2O3 oxide were determined by ratio of dissociation elasticity of the oxide and oxidation potential of the gas phase. In the СО – СО2 – С system, chromium is reduced at temperature of 1505 K if xCO > 0.9995. At this temperature, Cr2O3 compound is reduced in water gas of the following composition xH2 = 0.0186, xH2O = 0.28·10–4, xCO = 0.9809, xCO2 = 4.86·10–4, for which the oxidation potential is equal to dissociation elasticity of oxide With an increase in hydrogen concentration from 0.0186 to 0.99, oxidation potential of water gas in contact with carbon decreases by four orders of magnitude to This should lead to a significant increase in reduction rate. In such a gaseous atmosphere, it is possible to reduce chromium at temperature of 1230 K. It is technologically simple to obtain reducing water gas and at the lowest cost, for example, by heating water vapor in contact with carbon. It is shown that at temperature of 1500 K water gas is obtained with traces of Н2О and СО2 compounds with parameters xH2 = 0.4999, xCO = 0.4996, Oxidizing potential of such a gas is less than that of chromium oxide, and this difference significantly increases with increasing temperature.

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THERMODYNAMIC ANALYSIS OF IRON OXIDES REDUCTION USING CARBON AND WATER VAPOUR

Izvestiya Ferrous Metallurgy ◽

10.17073/0368-0797-2019-5-394-406 ◽

2019 ◽

Vol 62 (5) ◽

pp. 394-406

Author(s):

Yu. S. Kuznetsov ◽

O. I. Kachurina

Keyword(s):

Water Vapor ◽

Thermodynamic Analysis ◽

Total Carbon ◽

Isothermal Exposure ◽

Carbon Gasification ◽

Temperature Range ◽

Reduction Of Iron ◽

Co Dissociation ◽

Full Reduction ◽

Water Gas

Thermodynamic analysis was performed for complete reduction of iron oxide during heating the initial system «Fe3O4 (eo mol) – H2O (bo mol) – C (excess) » with isothermal exposure. By the nature of ongoing reactions, processes in the system can be divided into four stages. Carbon gasification by water vapor at temperatures below 880 K activates water gas reaction and CO dissociation to form black carbon. Composition of the resulting H2 – H2O – CO – CO2 gas mixture depends only on the temperature. The consumption of carbon at 880 K is ~0,4446 moles on 1 mole of water. Reduction of Fe3O4 to wustite FeO1+x with varying degrees of oxidation occurs in the temperature range 880 – 917 K. Hydrogen reduces oxide at temperatures above 888 K. The percentage part of a whole oxide Fe3O4 reduced by hydrogen into this temperature range increases from zero to ~63 %. The total number of Fe3O4, reduced to wustite at 917 K is ~123 moles for 1 mole of water. It is possible only with repeated regeneration of reductants CO and H2 according to the reactions of carbon gasification by water vapor and by dioxide CO2. The carbon expense is about 78 moles. Wustite FeO1.092 formed at 917 K can be reduced by monoxide CO only at temperatures of 917 – 955 K to wustite FeO1.054 with a lower degree of oxidation. Carbon is gasified only by dioxide CO2, the carbon expense is approximately 18 moles. When isothermal exposure is ~955 K, wustite is reduced to iron. Wustite can be reduced only by carbon monoxide. The carbon expense is approximately 257 mol. For full reduction of 123 mol of Fe3O4 in a mixture with an excess of carbon in a closed system at 1 atm, 1 mole of water is sufficient. The total carbon consumption is ~353 moles for obtaining 368 moles of Fe, or ~0.21 kg/kg iron.

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Residual Gas Reactions in the Electron Microscope: I. Qualitative Observations on the Water Gas Reaction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101207 ◽

1968 ◽

Vol 26 ◽

pp. 292-293

Author(s):

Richard E. Hartman ◽

Roberta S. Hartman ◽

Peter L. Ramos

Keyword(s):

Electron Beam ◽

Electron Microscope ◽

Gas Phase ◽

Absolute Temperature ◽

Residual Gas ◽

Gas Reactions ◽

Image Position ◽

The Right ◽

Water Gas ◽

Thinning Rate

The action of water and the electron beam on organic specimens in the electron microscope results in the removal of oxidizable material (primarily hydrogen and carbon) by reactions similar to the water gas reaction .which has the form:The energy required to force the reaction to the right is supplied by the interaction of the electron beam with the specimen.The mass of water striking the specimen is given by:where u = gH2O/cm2 sec, PH2O = partial pressure of water in Torr, & T = absolute temperature of the gas phase. If it is assumed that mass is removed from the specimen by a reaction approximated by (1) and that the specimen is uniformly thinned by the reaction, then the thinning rate in A/ min iswhere x = thickness of the specimen in A, t = time in minutes, & E = efficiency (the fraction of the water striking the specimen which reacts with it).

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Interaction of H2O, O2 and H2 with Proton Conducting Oxides Based on Lanthanum Scandates

Alternative Energy and Ecology (ISJAEE) ◽

10.15518/isjaee.2019.13-15.88-100 ◽

2019 ◽

pp. 88-100

Author(s):

A. S. Farlenkov ◽

N. A. Zhuravlev ◽

Т. A. Denisova ◽

М. V. Ananyev

Keyword(s):

Water Vapor ◽

Partial Pressure ◽

Gas Phase ◽

Molecular Hydrogen ◽

Proton Magnetic Resonance ◽

Partial Pressure Of Oxygen ◽

Proton Conducting ◽

Conducting Oxides ◽

Temperature Range ◽

Apparent Level

The research uses the method of high-temperature thermogravimetric analysis to study the processes of interaction of the gas phase in the temperature range 300–950 °C in the partial pressure ranges of oxygen 8.1–50.7 kPa, water 6.1–24.3 kPa and hydrogen 4.1 kPa with La1–xSrxScO3–α oxides (x = 0; 0.04; 0.09). In the case of an increase in the partial pressure of water vapor at a constant partial pressure of oxygen (or hydrogen) in the gas phase, the apparent level of saturation of protons is shown to increase. An increase in the apparent level of saturation of protons of the sample also occurs with an increase in the partial pressure of oxygen at a constant partial pressure of water vapor in the gas phase. The paper discusses the causes of the observed processes. The research uses the hydrogen isotope exchange method with the equilibration of the isotope composition of the gas phase to study the incorporation of hydrogen into the structure of proton-conducting oxides based on strontium-doped lanthanum scandates. The concentrations of protons and deuterons were determined in the temperature range of 300–800 °C and a hydrogen pressure of 0.2 kPa for La0.91Sr0.09ScO3–α oxide. The paper discusses the role of oxygen vacancies in the process of incorporation of protons and deuterons from the atmosphere of molecular hydrogen into the structure of the proton conducting oxides La1–xSrxScO3–α (x = 0; 0.04; 0.09). The proton magnetic resonance method was used to study the local structure in the temperature range 23–110 °C at a rotation speed of 10 kHz (MAS) for La0.96Sr0.04ScO3–α oxide after thermogravimetric measurements in an atmosphere containing water vapor, and after exposures in molecular hydrogen atmosphere. The existence of proton defects incorporated into the volume of the investigated proton oxide from both the atmosphere containing water and the atmosphere containing molecular hydrogen is unambiguously shown. The paper considers the effect of the contributions of the volume and surface of La0.96Sr0.04ScO3–α oxide on the shape of the proton magnetic resonance spectra.

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Upcycling of Vine Shoots: Production of Fillers for PHBV-Based Biocomposite Applications

Journal of Polymers and the Environment ◽

10.1007/s10924-020-01884-8 ◽

2020 ◽

Cited By ~ 1

Author(s):

Grégoire David ◽

Laurent Heux ◽

Stéphanie Pradeau ◽

Nathalie Gontard ◽

Hélène Angellier-Coussy

Keyword(s):

Water Vapor ◽

Gas Phase ◽

Mechanical Performance ◽

Low Cost ◽

Water Vapor Permeability ◽

Contact Angles ◽

Vapor Permeability ◽

Water Contact ◽

Median Diameter ◽

Cost Of Materials

Abstract This paper aims at investigating the potential of vine shoots (ViSh) upcycling as fillers in novel poly(3-hydroxybutyrate-3-hydroxyvalerate) (PHBV) based biocomposites. ViSh particles of around 50 µm (apparent median diameter) were obtained combining dry grinding processes, and mixed with PHBV using melt extrusion. Thermal stability and elongation at break of biocomposites were reduced with increasing contents of ViSh particles (10, 20 and 30 wt%), while Young’s modulus and water vapor permeability were increased. It was shown that a surface gas-phase esterification allowed to significantly increase the hydrophobicity of ViSh particles (increase of water contact angles from 59° to 114°), leading to a reduction of 27% in the water vapor permeability of the biocomposite filled with 30 wt% of ViSh. The overall mechanical performance was not impacted by gas-phase esterification, demonstrating that the interfacial adhesion between the virgin ViSh particles and the PHBV matrix was already good and that such filler surface treatment was not required in that case. It was concluded that ViSh particles can be interestingly used as low cost fillers in PHBV-based biocomposites to decrease the overall cost of materials.

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Effects of water vapor on activated carbon load equalization of gas phase toluene

Water Research ◽

10.1016/j.watres.2010.04.028 ◽

2010 ◽

Vol 44 (13) ◽

pp. 3924-3934 ◽

Cited By ~ 10

Author(s):

Marilou M. Nabatilan ◽

William M. Moe

Keyword(s):

Activated Carbon ◽

Water Vapor ◽

Gas Phase ◽

Carbon Load

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Water vapor sorption on Marcellus shale: measurement, modeling and thermodynamic analysis

Fuel ◽

10.1016/j.fuel.2017.07.062 ◽

2017 ◽

Vol 209 ◽

pp. 606-614 ◽

Cited By ~ 27

Author(s):

Xu Tang ◽

Nino Ripepi ◽

Katherine A. Valentine ◽

Cigdem Keles ◽

Timothy Long ◽

...

Keyword(s):

Water Vapor ◽

Thermodynamic Analysis ◽

Marcellus Shale ◽

Water Vapor Sorption ◽

Vapor Sorption

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Variation of Runoff and Runoff Components of the Upper Shule River in the Northeastern Qinghai–Tibet Plateau under Climate Change

Water ◽

10.3390/w13233357 ◽

2021 ◽

Vol 13 (23) ◽

pp. 3357

Author(s):

Jinkui Wu ◽

Hongyuan Li ◽

Jiaxin Zhou ◽

Shuya Tai ◽

Xueliang Wang

Keyword(s):

Climate Change ◽

Sustainable Use ◽

Reduction Rate ◽

Northwest China ◽

Tibet Plateau ◽

Glacier Area ◽

Rainfall Runoff ◽

Total Runoff ◽

Increasing Temperature ◽

The Impact

Quantifying the impact of climate change on hydrologic features is essential for the scientific planning, management and sustainable use of water resources in Northwest China. Based on hydrometeorological data and glacier inventory data, the Spatial Processes in Hydrology (SPHY) model was used to simulate the changes of hydrologic processes in the Upper Shule River (USR) from 1971 to 2020, and variations of runoff and runoff components were quantitatively analyzed using the simulations and observations. The results showed that the glacier area has decreased by 21.8% with a reduction rate of 2.06 km2/a. Significant increasing trends in rainfall runoff, glacier runoff (GR) and baseflow indicate there has been a consistent increase in total runoff due to increasing rainfall and glacier melting. The baseflow has made the largest contribution to total runoff, followed by GR, rainfall runoff and snow runoff, with mean annual contributions of 38%, 28%, 18% and 16%, respectively. The annual contribution of glacier and snow runoff to the total runoff shows a decreasing trend with decreasing glacier area and increasing temperature. Any increase of total runoff in the future will depend on an increase of rainfall, which will exacerbate the impact of drought and flood disasters.

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