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In this work, the concentration of cathodic copper is carefully controlled by employing a "proton-pump" configuration in a H2SO4 media, preventing complications from anodic reactions or speciation. When run in the proton-pump mode...
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In this work, the concentration of cathodic copper is carefully controlled by employing a "proton-pump" configuration in a H2SO4 media, preventing complications from anodic reactions or speciation. When run in the proton-pump mode 0.5 M H2SO4 was used as the catholyte while the anolyte was humidified hydrogen gas. The catholyte was then spiked with various amounts of Cu2+ and the effects of copper concentration were investigated using a variety of electrochemical tests including cyclic voltammetry (CV), linear sweep voltammetry (LSV) and potential stair-step voltammetry. Galvanostatic tests were performed at a constant current density of 300 mA/cm(2) to determine the effect of copper concentration on the voltage and hydrogen production efficiency. Our results show that the presence of copper does in fact impact the system, by decreasing the voltage efficiency. However, the coulombic hydrogen production efficiency was unaffected by increasing catholyte copper concentration. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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This paper presents an overview of the status of Canada's program on nuclear hydrogen production and the thermochemical copper-chlorine (Cu—Cl) cycle. Enabling technologies for the Cu-Cl cycle are being developed by a Canadian co...
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This paper presents an overview of the status of Canada's program on nuclear hydrogen production and the thermochemical copper-chlorine (Cu—Cl) cycle. Enabling technologies for the Cu-Cl cycle are being developed by a Canadian consortium, as part of the Generation IV International Forum (GIF) for hydrogen production with the next generation of nuclear reactors. Particular emphasis in this paper is given to hydrogen production with Canada's Super-Critical Water Reactor, SCWR. Recent advances towards an integrated lab-scale Cu-Cl cycle are discussed, including experimentation, modeling, simulation, advanced materials, thermochemistry, safety, reliability and economics. In addition, electrolysis during off-peak hours, and the processes of integrating hydrogen plants with Canada's nuclear plants are presented.
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This paper presents recent advances by an international team which is developing the thermochemical copper-chlorine (Cu-Cl) cycle for hydrogen production. Development of the Cu-Cl cycle has been pursued by several countries within...
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This paper presents recent advances by an international team which is developing the thermochemical copper-chlorine (Cu-Cl) cycle for hydrogen production. Development of the Cu-Cl cycle has been pursued by several countries within the framework of the Generation IV International Forum (GIF) for hydrogen production with the next generation of nuclear reactors. Due to its lower temperature requirements in comparison with other thermochemical cycles, the Cu-Cl cycle is particularly well matched with Canada's Generation IV reactor, SCWR (Super-Critical Water Reactor), as well as other heat sources such as solar energy or industrial waste heat. In this paper, recent developments of the Cu -Cl cycle are presented, specifically involving unit operation experiments, corrosion resistant materials and system integration.
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The impact of exit streams containing byproducts of incomplete reactions in an integrated thermochemical copper—chlorine (Cu—Cl) cycle of hydrogen production is studied in this paper. In the hydrolysis reaction, CuCl_2reacts wit...
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The impact of exit streams containing byproducts of incomplete reactions in an integrated thermochemical copper—chlorine (Cu—Cl) cycle of hydrogen production is studied in this paper. In the hydrolysis reaction, CuCl_2reacts with steam to produce solid copper oxy-chloride. If the hydrolysis reaction does not proceed to completion, particles of un-reacted CuCl_2 will be transferred to a downstream molten salt reactor where oxygen is released from copper oxychloride decomposition. Undesirable chlorine may also be released as a result of CuCl_2 decomposition together with oxygen, resulting in a mass imbalance of the overall cycle. This paper also examines the implications of incomplete hydrolysis reactions on the kinetics and thermodynamics of the oxygen reactor in the Cu-Cl cycle, specifically the spontaneity of CuCl_2 decomposition and parameters that minimize the release of chlorine. Theoretical analysis of the decomposition of a mixture of CuO and CuCl_2 is also performed in this paper. It is found that usage of copper oxychloride is preferable over a mixture of CuCl_2 and CuO in the oxygen production reaction of the Cu—Cl cycle.
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The Advanced Photon Source (APS) at Argonne National Laboratory was used to investigate the progress of two of the reactions of the copper-chlorine cycle for production of hydrogen in situ by studying the evolution of the solid Cu...
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The Advanced Photon Source (APS) at Argonne National Laboratory was used to investigate the progress of two of the reactions of the copper-chlorine cycle for production of hydrogen in situ by studying the evolution of the solid Cu species, using X-ray absorption near edge structure (XANES) spectroscopy. The hydrolysis of CuCl2 (2 CuCl2 + H2O -> Cu2OCl2 + 2 HCl) was studied under low and high steam-to-copper ratios from 423 to 725 K, and the decomposition of Cu2OCl2 (Cu2OCl2 -> 2 CuCl + A1/2 O-2) in dry and humidified nitrogen up to 750 K. This study showed that the formation of Cu2OCl2 by hydrolysis of CuCl2 is more favorable under low steam-to-copper mole ratios and it reaches a maximum around 675 K. Over this limit, the formation of CuO and Cl-2 as reaction byproducts starts to be noticeable. The same reaction byproducts were observed to form under all of the other experimental conditions and at temperatures as low as 635 K. The results from the decomposition studied by XANES are in very good agreement with calorimetric studies (TG/DSC) and they confirm that the formation of Cl-2 takes place in the early stages of the decomposition of Cu2OCl2. To the best of our knowledge, this is the first time that the XANES spectrum of a Cu2OCl2 standard has been reported, since in previous studies Cu2OCl2 was always a reaction intermediate.
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In this paper, energy and exergy analyses of the geothermal-based hydrogen production via thermo-chemical water decomposition using a new, four-step copper-chlorine (Cu-Cl) cycle are conducted, and the respective cycle energy and ...
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In this paper, energy and exergy analyses of the geothermal-based hydrogen production via thermo-chemical water decomposition using a new, four-step copper-chlorine (Cu-Cl) cycle are conducted, and the respective cycle energy and exergy efficiencies are examined. Also, a parametric study is performed to investigate how each step of the cycle and its overall cycle performance are affected by reference environment temperatures, reaction temperatures, as well as energy efficiency of the geothermal power plant itself. As a result, overall energy and exergy efficiencies of the cycle are found to be 21.67% and 19.35%, respectively, for a reference case.
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In this paper, an atmospheric-pressure distillation system is designed and constructed for partial to separation of hydrochloric acid and water. The system concentrates HCl(aq) between the electrolyzer and hydrolysis processes of ...
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In this paper, an atmospheric-pressure distillation system is designed and constructed for partial to separation of hydrochloric acid and water. The system concentrates HCl(aq) between the electrolyzer and hydrolysis processes of the Copper-Chlorine (Cu-Cl) cycle for hydrogen production. The motivation behind this study is to investigate azeotropic separation of HCl(aq), as needed for integration of unit operations in the Cu-Cl cycle. The separation is only partial, as the mixture is unable to cross the azeotrope with only a single pressure. The distillation system consists primarily of one packed distillation column, which employs heating tapes and thermocouples to achieve a desired axial temperature profile. The column can be operated in batch or continuous mode. The distillate is H 2O(1) and the bottoms is HCl(aq) near the azeotropic concentration; feed concentrations are less than azeotrope. Thus, the degree of separation is determined to be independent of the feed concentration. The bottoms concentration varies from experiment to experiment, but does so independently of feed concentration, likely the result of corrosion impurities affecting the calculation of its concentration. It is found that HCl(aq) can be concentrated up to approximately 0.1068 mol/mol from an initial concentration of 0.0191 mol/mol. A simulation of pressure-swing distillation (PSD) is also performed, but due to safety constraints (a column operating at 10 atm must be certified to CSA B51), a single-pressure (single-column) distillation is physically performed. A single-pressure column is beneficial to the Cu-Cl cycle because it partially recycles HCl, which reduces the cost of the cycle, and still provides valuable results for analysis. The maximum HCl concentration achieved experimentally is 0.1068 mol/mol and the maximum HCl concentration determined from simulation is 0.11 mol/mol (the azeotropic concentration). The novelty of this research is that the experimental column built to study HCl partial separation is designed to be simple yet safe to integrate within the Cu-Cl cycle for hydrogen production. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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The Cu-CI (copper-chlorine) thermochemical cycles for hydrogen production are leading examples of water-splitting methods. In this article, the heat requirements of different types of Cu-Clcycles with various numbers of steps are ...
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The Cu-CI (copper-chlorine) thermochemical cycles for hydrogen production are leading examples of water-splitting methods. In this article, the heat requirements of different types of Cu-Clcycles with various numbers of steps are analyzed, and their thermal design features are discussed in terms of water requirements, heat quantity, and heat grade. A challenge arises from the excess steam quantity requirement in the hydrolysis of CuCl_2. To address this challenge, a new type of Cu-CI cycle is proposed in this article. It is found that the steam requirement can decrease by up to ten times, compared with conventional Cu-CI cycles, and the heat grade of the hydrolysis step in the new cycle is significantly lowered from 375°C to 150℃. The engineering challenges of the new cycle are also discussed in the article.
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Copper-Chlorine cycle has been identified as the most prospective among the low temperature thermochemical cycles for hydrogen production. The cycle consists of two thermal reaction steps, one electrochemical step and a physical s...
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Copper-Chlorine cycle has been identified as the most prospective among the low temperature thermochemical cycles for hydrogen production. The cycle consists of two thermal reaction steps, one electrochemical step and a physical separation step. The two thermal reaction steps, hydrolysis and thermolysis are carried out in series for water splitting and oxygen production, respectively. The solid product from hydrolysis step Cu2OCl2 enters the thermolysis step where it undergoes decomposition to CuCl and O-2. In the present work, thermolysis experiments were carried out in a laboratory scale horizontal furnace reactor with CuO-CuCl2 equimolar mixture and Cu2OCl2 in the temperature range of 470-575 degrees C. Experiments in furnace reactor show that, under otherwise same conditions, similar conversions are obtained with Cu2OCl2 as well as with the equimolar mixture of CuO-CuCl2. It was also observed that the conversion increased with an increase in CuCl2 percentage in the reaction mixture. From the experimental data, an attempt has been made to provide insights into the reaction mechanism and kinetics. These results are expected to be useful for the design and scale-up of the thermolysis reactor. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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This paper proposes the conceptual integration of a Generation IV nuclear reactor, the gas-cooled fast nuclear reactor, and the thereto-electrochemical copper-chlorine cycle, a Brayton cycle, and a Rankine cycle for hydrogen and e...
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This paper proposes the conceptual integration of a Generation IV nuclear reactor, the gas-cooled fast nuclear reactor, and the thereto-electrochemical copper-chlorine cycle, a Brayton cycle, and a Rankine cycle for hydrogen and electricity production. This paper analyzes the developed system thermodynamically, and energy and exergy efficiencies are used to measure the system performance. Here, the four-step thereto-electrochemical copper-chlorine cycle produces hydrogen through thermochemical water decomposition, and electricity via the Rankine and Brayton cycles. The produced hydrogen is then compressed to reduce its storage volume. The proposed system uses a heat exchanger network, which is incorporated within the hydrogen producing copper-chlorine cycle. With the heat recovery network, the heat from the nuclear reactor is delivered to only two reactors of the four-step copper-chlorine cycle. The proposed system is modeled and simulated with engineering process simulation software (Aspen Plus). The overall energy and exergy efficiencies of the system are 14.1% and 20.7%, respectively.
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