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H Y Sohn - One of the best experts on this subject based on the ideXlab platform.
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a novel Cyclic Process using caso4 cas pellets for converting sulfur dioxide to elemental sulfur without generating secondary pollutants part ii hydrogen reduction of calcium sulfate pellets to calcium sulfide
Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2002Co-Authors: Byung Su Kim, H Y SohnAbstract:The reduction of calcium sulfate to produce calcium sulfide is a part of the Cyclic Process for converting sulfur dioxide to elemental sulfur that is described in Part I. The kinetics of the hydrogen reduction of nickel-catalyzed calcium-sulfate pellets were investigated using a thermogravimetric analysis (TGA) technique at reaction temperatures between 1023 and 1088 K and hydrogen partial pressures between 12.9 and 86.1 kPa. The reactivity of nickel-catalyzed calcium-sulfate pellets was demonstrated by the conversion of 70 pct fresh nickel-catalyzed calcium sulfate to calcium sulfide in 20 minutes at 1073 K under a hydrogen partial pressure of 86.1 kPa. Furthermore, the reactivity remained relatively intact after ten cycles of reactions and regenerations. This observed characteristic of the pellets is important because the solids must be reusable for repeated cycles to avoid generating secondary pollutants. The nucleation and growth rate expression was found to be useful in describing the kinetics of the reaction, which had an activation energy of about 167 kJ/mol (∼40 kcal/mol) in all reaction cycles except for the first regenerated samples that were lower at 146 kJ/mol (35 kcal/mol). The reaction order with respect to hydrogen partial pressure was 0.22 in all cycles with the exception of the first regenerated sample for which it was 0.37.
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a novel Cyclic reaction system involving cas and caso4 for converting sulfur dioxide to elemental sulfur without generating secondary pollutants 3 kinetics of the hydrogen reduction of the calcium sulfate powder to calcium sulfide
Industrial & Engineering Chemistry Research, 2002Co-Authors: Byung Su Kim, H Y SohnAbstract:The reduction of calcium sulfate to produce calcium sulfide is not only a part of the Cyclic Process for converting sulfur dioxide to elemental sulfur described in part 1 of this series but also of interest as a means of producing elemental sulfur from gypsum. This reaction was investigated using a thermogravimetric analysis technique in the absence and presence of an impregnated nickel catalyst at reaction temperatures between 973 and 1153 K and hydrogen partial pressures between 1.7 and 86.1 kPa. As an example of the reactivity of the nickel-catalyzed calcium sulfate powder, more than 95% of fresh nickel-catalyzed calcium sulfate powders was converted to calcium sulfide in 20 min at 1123 K under a hydrogen partial pressure of 86.1 kPa. Furthermore, the reactivity remained relatively intact after 10 cycles of reactions and regenerations, which is important because the solids must be reusable for repeated cycles to avoid generating secondary pollutants. The Erofeev nucleation and growth kinetics equation ...
Byung Su Kim - One of the best experts on this subject based on the ideXlab platform.
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a novel Cyclic Process using caso4 cas pellets for converting sulfur dioxide to elemental sulfur without generating secondary pollutants part i feasibility and kinetics of the reduction of sulfur dioxide with calcium sulfide pellets
Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2002Co-Authors: Byung Su KimAbstract:Certain new sulfide-smelting Processes and coal-gasification Processes generate high-strength sulfur dioxide streams, for which a new Process for converting sulfur dioxide to elemental sulfur needs to be developed because no Process exists that is generally and economically applicable to the treatment of such streams. A thermodynamic and experimental investigation to develop a new Process for converting sulfur dioxide to elemental sulfur by a Cyclic Process involving calcium sulfide and calcium sulfate without generating secondary pollutants was carried out. In this Process, the starting raw material, calcium sulfate, is reduced by a suitable reducing agent, such as hydrogen, to produce calcium sulfide, which is used to reduce sulfur dioxide to elemental sulfur vapor and calcium sulfate. The latter is, in turn, reduced to regenerate calcium sulfide. In this Part I, detailed experimental results are presented on the kinetics of the reaction between sulfur dioxide and calcium-sulfide pellets, which produces elemental sulfur and calcium sulfate. The experiments were carried out at temperatures between 1023 and 1088 K and sulfur-dioxide partial pressures between 9 and 60 kPa by the use of a thermogravimetric analysis (TGA) technique. The rate of this reaction was demonstrated by the conversion of 40 pct calcium-sulfide pellets obtained from the hydrogen reduction of fresh calcium sulfate in 10 minutes at 1073 K under a sulfur-dioxide partial pressure of 43 kPa. The reactivity decreased somewhat during the first three cycles but remained largely unchanged thereafter up to the tenth cycle. This characteristic of the pellets is important because the solids must be reusable for repeated cycles to avoid generating secondary pollutants. A pore-blocking model was found to fit the reaction rate. The reaction is first order with respect to sulfur-dioxide partial pressure and has an activation energy of 101 to 134 kJ/mol (24 to 32 kcal/mol) for calcium-sulfide pellets reacted and regenerated several different times. Sulfur dioxide-containing streams from certain sources, such as the regenerator off-gas from an integrated-gasification, combined-cycle, desulfurization unit and new sulfide-smelting plants, contain much higher partial pressures of SO2. In these cases, the rate of the first reaction is expected to be proportionally higher than in the test conditions reported in this article. The reduction kinetics of calcium-sulfate pellets with hydrogen gas is reported in the accompanying Part II.
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a novel Cyclic Process using caso4 cas pellets for converting sulfur dioxide to elemental sulfur without generating secondary pollutants part ii hydrogen reduction of calcium sulfate pellets to calcium sulfide
Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2002Co-Authors: Byung Su Kim, H Y SohnAbstract:The reduction of calcium sulfate to produce calcium sulfide is a part of the Cyclic Process for converting sulfur dioxide to elemental sulfur that is described in Part I. The kinetics of the hydrogen reduction of nickel-catalyzed calcium-sulfate pellets were investigated using a thermogravimetric analysis (TGA) technique at reaction temperatures between 1023 and 1088 K and hydrogen partial pressures between 12.9 and 86.1 kPa. The reactivity of nickel-catalyzed calcium-sulfate pellets was demonstrated by the conversion of 70 pct fresh nickel-catalyzed calcium sulfate to calcium sulfide in 20 minutes at 1073 K under a hydrogen partial pressure of 86.1 kPa. Furthermore, the reactivity remained relatively intact after ten cycles of reactions and regenerations. This observed characteristic of the pellets is important because the solids must be reusable for repeated cycles to avoid generating secondary pollutants. The nucleation and growth rate expression was found to be useful in describing the kinetics of the reaction, which had an activation energy of about 167 kJ/mol (∼40 kcal/mol) in all reaction cycles except for the first regenerated samples that were lower at 146 kJ/mol (35 kcal/mol). The reaction order with respect to hydrogen partial pressure was 0.22 in all cycles with the exception of the first regenerated sample for which it was 0.37.
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a novel Cyclic reaction system involving cas and caso4 for converting sulfur dioxide to elemental sulfur without generating secondary pollutants 3 kinetics of the hydrogen reduction of the calcium sulfate powder to calcium sulfide
Industrial & Engineering Chemistry Research, 2002Co-Authors: Byung Su Kim, H Y SohnAbstract:The reduction of calcium sulfate to produce calcium sulfide is not only a part of the Cyclic Process for converting sulfur dioxide to elemental sulfur described in part 1 of this series but also of interest as a means of producing elemental sulfur from gypsum. This reaction was investigated using a thermogravimetric analysis technique in the absence and presence of an impregnated nickel catalyst at reaction temperatures between 973 and 1153 K and hydrogen partial pressures between 1.7 and 86.1 kPa. As an example of the reactivity of the nickel-catalyzed calcium sulfate powder, more than 95% of fresh nickel-catalyzed calcium sulfate powders was converted to calcium sulfide in 20 min at 1123 K under a hydrogen partial pressure of 86.1 kPa. Furthermore, the reactivity remained relatively intact after 10 cycles of reactions and regenerations, which is important because the solids must be reusable for repeated cycles to avoid generating secondary pollutants. The Erofeev nucleation and growth kinetics equation ...
Kyle C Smith - One of the best experts on this subject based on the ideXlab platform.
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nickel hexacyanoferrate electrodes for continuous cation intercalation desalination of brackish water
Electrochimica Acta, 2017Co-Authors: S Porada, Aniruddh Shrivastava, Pamela Bukowska, P. Maarten Biesheuvel, Kyle C SmithAbstract:Abstract Using porous electrodes containing redox-active nickel hexacyanoferrate (NiHCF) nanoparticles, we construct and test a device for capacitive deionization in a two flow-channel device where the intercalation electrodes are in direct contact with an anion-exchange membrane. Upon reduction of NiHCF, cations intercalate into it and the water in its vicinity is desalinated; at the same time water in the opposing electrode becomes more saline upon oxidation of NiHCF in that electrode. In a Cyclic Process of charge and discharge, fresh water is continuously produced, alternating between the two channels in sync with the direction of applied current. We present proof-of-principle experiments of this technology for single salt solutions, where we analyze various levels of current and cycle durations. We analyze salt removal rate and energy consumption. In desalination experiments with salt mixtures we find a threefold enhancement for K + over Na + -adsorption, which shows the potential of NiHCF intercalation electrodes for selective ion separation from mixed ionic solutions.
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nickel hexacyanoferrate electrodes for cation intercalation desalination
2016Co-Authors: S Porada, Aniruddh Shrivastava, Pamela Bukowska, P. Maarten Biesheuvel, Kyle C SmithAbstract:Using porous electrodes containing nickel hexacyanoferrate (NiHCF) nanoparticles, we construct and test a device for capacitive deionization in a two flow-channel device where the intercalation electrodes are in direct contact with an anion-exchange membrane. Upon negatively charging NiHCF, cations intercalate into it and the water in its vicinity is desalinated; at the same time water in the opposing electrode becomes more saline upon positively charging the NiHCF in that electrode. In a Cyclic Process of charge and discharge, fresh water is continuously produced, alternating between the two channels in sync with the direction of applied current. We present proof-of-principle experiments of this technology for single salt solutions, where we analyze various levels of current and cycle durations. We analyze salt removal rate and energy consumption. In desalination experiments with salt mixtures we find a threefold enhancement for K$^+$ over Na$^+$-adsorption, which shows the potential of NiHCF intercalation electrodes for selective ion separation from mixed ionic solutions.
Aldo Steinfeld - One of the best experts on this subject based on the ideXlab platform.
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co2 capture from atmospheric air via consecutive cao carbonation and caco3 calcination cycles in a fluidized bed solar reactor
Chemical Engineering Journal, 2009Co-Authors: V Nikulshina, Aldo Steinfeld, Christoph GebaldAbstract:Abstract A thermochemical Cyclic Process and associated reactor is presented for the continuous removal of CO2 from ambient air via consecutive CaO-carbonation and CaCO3-calcination steps using concentrated solar energy as the source of high-temperature Process heat. A fluidized-bed solar reactor is applied to accomplish the carbonation at 365–400 °C and the calcination at 800–875 °C, with reacting particles directly exposed to high-flux solar irradiation. Water vapor was introduced during the carbonation step to enhance its kinetics. Five consecutive cycles were performed, yielding complete removal of CO2 from a continuous airflow containing 500 ppm of CO2 within a residence time of 1.3 s during each carbonation step, and subsequent complete release of CO2 and regeneration of the CaO reacting particles during the calcination step. The reactor design, set-up, and experimentation using a high-flux solar simulator are described.
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solar hydrogen production via a two step thermochemical Process based on mgo mg redox reactions thermodynamic and kinetic analyses
International Journal of Hydrogen Energy, 2008Co-Authors: Maria Elena Galvez, Aldo Steinfeld, A Frei, G Albisetti, G LunardiAbstract:Abstract Solar hydrogen production via a two-step water-splitting thermochemical Cyclic Process is considered via MgO/Mg redox reactions. The first endothermic step is the production of Mg by carbothermal or methanothermal reduction of MgO, using concentrated solar energy as the source of high-temperature Process heat. The second exothermic step is the steam-hydrolysis of Mg for the production of H 2 and MgO; the latter is recycled to the first step. Both reaction steps have been thermodynamically examined and experimentally investigated by means of thermogravimetric analysis. The carbothermal reduction of MgO was performed in the temperature range 1450–1550 °C using wood charcoal and petroleum coke as reducing agents. The steam-hydrolysis of Mg was studied in the temperature range 350–550 °C using various water vapor concentrations. Solid products were characterized via BET, XRD, and SEM. The rate laws of both reaction steps were determined by applying either a solid–solid diffusion kinetic model or the gas–solid shrinking core kinetic model.
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ammonia production via a two step al2o3 aln thermochemical cycle 1 thermodynamic environmental and economic analyses
Industrial & Engineering Chemistry Research, 2007Co-Authors: Maria Elena Galvez, M Halmann, Aldo SteinfeldAbstract:The production of ammonia via a two-step Cyclic Process is proposed as an alternative to its conventional production by the Haber−Bosch Process. The first endothermic step is the production of AlN by carbothermal reduction of Al2O3 in a N2 atmosphere at above 1500 °C. The second exothermic step is the steam-hydrolysis of AlN to produce NH3 and reform Al2O3; the latter is recycled to the first step. Both reaction steps proceed at 1 bar, without added catalysts, and bypass the energy-intensive production of hydrogen, resulting in significant fuel and cost savings. Furthermore, the endothermic reduction step could be carried out using concentrated solar energy as the source of high-temperature Process heat, eliminating concomitant CO2 emissions derived from fossil-fuelled Processes.
S Porada - One of the best experts on this subject based on the ideXlab platform.
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nickel hexacyanoferrate electrodes for continuous cation intercalation desalination of brackish water
Electrochimica Acta, 2017Co-Authors: S Porada, Aniruddh Shrivastava, Pamela Bukowska, P. Maarten Biesheuvel, Kyle C SmithAbstract:Abstract Using porous electrodes containing redox-active nickel hexacyanoferrate (NiHCF) nanoparticles, we construct and test a device for capacitive deionization in a two flow-channel device where the intercalation electrodes are in direct contact with an anion-exchange membrane. Upon reduction of NiHCF, cations intercalate into it and the water in its vicinity is desalinated; at the same time water in the opposing electrode becomes more saline upon oxidation of NiHCF in that electrode. In a Cyclic Process of charge and discharge, fresh water is continuously produced, alternating between the two channels in sync with the direction of applied current. We present proof-of-principle experiments of this technology for single salt solutions, where we analyze various levels of current and cycle durations. We analyze salt removal rate and energy consumption. In desalination experiments with salt mixtures we find a threefold enhancement for K + over Na + -adsorption, which shows the potential of NiHCF intercalation electrodes for selective ion separation from mixed ionic solutions.
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nickel hexacyanoferrate electrodes for cation intercalation desalination
2016Co-Authors: S Porada, Aniruddh Shrivastava, Pamela Bukowska, P. Maarten Biesheuvel, Kyle C SmithAbstract:Using porous electrodes containing nickel hexacyanoferrate (NiHCF) nanoparticles, we construct and test a device for capacitive deionization in a two flow-channel device where the intercalation electrodes are in direct contact with an anion-exchange membrane. Upon negatively charging NiHCF, cations intercalate into it and the water in its vicinity is desalinated; at the same time water in the opposing electrode becomes more saline upon positively charging the NiHCF in that electrode. In a Cyclic Process of charge and discharge, fresh water is continuously produced, alternating between the two channels in sync with the direction of applied current. We present proof-of-principle experiments of this technology for single salt solutions, where we analyze various levels of current and cycle durations. We analyze salt removal rate and energy consumption. In desalination experiments with salt mixtures we find a threefold enhancement for K$^+$ over Na$^+$-adsorption, which shows the potential of NiHCF intercalation electrodes for selective ion separation from mixed ionic solutions.
