Experimental study and development of an improved sulfur–iodine cycle integrated with HI electrolysis for hydrogen production

Ying, Zhi; Wang, Yabin; Zheng, Xiaoyuan; Zhang, Geng; Dou, Binlin; Cui, Guomin

doi:10.1016/j.ijhydene.2020.03.037

Cited by 34 publications

(22 citation statements)

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“…Reductive elimination of chlorine and bromine from high valent transition metals is still a challenge in the context of catalytic HX splitting for energy conversion and usually only achieved under photolytic conditions and in the presence of reductive halogen traps . In particular, HI splitting into iodine and hydrogen is a key step in the sulfur–iodine thermochemical water-splitting cycle and is considered to be the bottleneck reaction . In this paper we also disclose the trap-free reductive elimination of iodine from a Ir(IV) iodo complex that represents the first example of a reductive elimination from a well characterized, formally d 5 metal complex.…”

Section: Introductionmentioning

confidence: 93%

Ir(IV) Sulfoxide-Pincer Complexes by Three-Electron Oxidative Additions of Br₂ and I₂. Unprecedented Trap-Free Reductive Elimination of I₂ from a formal d⁵ Metal

et al. 2022

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Oxidative addition of 1.5 equiv of bromine or iodine to a Ir(I) sulfoxide pincer complex affords the corresponding Ir(IV) tris-bromido or tris-iodido complexes, respectively. The unprecedented trap-free reductive elimination of iodine from the Ir(IV)-iodido complex is induced by coordination of ligands or donor solvents. In the case of added I − , the isostructural tris-iodo Ir(III)-ate complex is quickly generated, which then can be readily reoxidized to the Ir(IV)-iodido complex with FcPF 6 or electrochemically. DFT calculations indicate an "inverted ligand field" in the Ir(IV) complexes and favor dinuclear pathways for the reductive elimination of iodine from the formal d 5 metal center.

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Section: Introductionmentioning

confidence: 93%

Ir(IV) Sulfoxide-Pincer Complexes by Three-Electron Oxidative Additions of Br₂ and I₂. Unprecedented Trap-Free Reductive Elimination of I₂ from a formal d⁵ Metal

et al. 2022

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“…Many thermochemical cycles have been tested for their suitability for hydrogen production. Two such widely studied thermochemical cycles, (1) S-I cycle [7][8][9][10] and (2) Cu-Cl cycle [11,12], were found to be promising for large-scale hydrogen production. Recent advancements in high-temperature nuclear reactors (HTRs) have provided an appropriate design to couple thermochemical cycles with nuclear reactors and utilize the waste heat for their working at moderate temperatures [13,14].…”

Section: Introductionmentioning

confidence: 99%

Cu–Cl Thermochemical Water Splitting Cycle: Probing Temperature-Dependent CuCl2 Hydrolysis and Thermolysis Reaction Using In Situ XAS

Singh

Pai

Banerjee

et al. 2021

J Therm Anal Calorim

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Recently, we reported detailed investigations on a hydrolysis step of Cu-Cl thermochemical cycle (Singh et al. in Int J Energy Res 44:2845-2863 where we demonstrated CuCl 2 hydrolysis using a fixed-bed reactor under optimized conditions. Thermolysis of CuCl 2 and oxide formation are associated hindrances in achieving 100% phase-pure hydrolysis product, Cu 2 OCl 2 . With an objective to understand the thermolysis and hydrolysis processes at molecular level, both these reactions were investigated independently in the present study using in situ XAS as a probe. The progress of both the reactions was recorded from RT to 400 °C by monitoring temperature-dependent evolution of Cu species using Cu K-edge XAS measurements at BL-09, Indus-2 SRS, RRCAT, Indore, India. XAS results are also corroborated with ex situ analysis by XRD and TG of samples containing various compositions of CuCl 2 mixed with boron nitride (pellets employed for XAS). Besides LCF, hydrolysis product Cu 2 OCl 2 yield was further supported by chemical titrations. EXAFS revealed that with increasing temperature, coordination of Cu atoms in reactant CuCl 2 progressively decreased during thermolysis. For hydrolysis process, coordination of Cu atoms in Cu-Cu, Cu-O and Cu-Cl linkages approached towards that of Cu 2 OCl 2 and CuO. CuCl 2 diminished and transformed into CuCl (88 mass%) at 350 °C during thermolysis and ~ 60 mass% of Cu 2 OCl 2 and 40 mass% of CuO during hydrolysis reaction. Based on in situ investigations in the present study, the most probable reactions taking place during CuCl 2 hydrolysis at different temperatures are proposed for S/Cu of 14.6.

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“…Goldstein et al 31 and Wang and Macián‐Juan 43 both assumed that the heat released by the condenser of distillation column could be fully recovered. Some studies 36,39,40,46 proposed that waste heat with a temperature higher than 313 K could be converted into the electricity required by the EED at a ratio of 15%.…”

Section: More Realistic Estimationmentioning

confidence: 99%

“…41 The energy consumption of the mixing and separation process is small and negligible, so the energy consumption of the entire Bunsen section can be ignored. 39 Wang et al 41 also indicated that more than 99% of the energy consumption of the IS process is occupied by the H 2 SO 4 and HI sections. Therefore, this study discusses the thermal efficiency of hydrogen production and designs the heat exchange network based on the energy consumption and the flowsheets of H 2 SO 4 and HI sections.…”

Section: Upper Bound Of Thermal Efficiency For Hydrogen Productionmentioning

confidence: 99%

Analysis of internal heat exchange network and hydrogen production efficiency of iodine–sulfur cycle for nuclear hydrogen production

Peng

et al. 2022

Intl J of Energy Research

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Summary Nuclear energy enables large‐scale carbon‐free hydrogen production, and the coupling of the very‐high‐temperature gas‐cooled reactor and iodine–sulfur (IS) cycle has the potential to achieve efficient hydrogen production. This study develops the flowsheet of IS process, performs process simulation, designs the internal heat exchange network using pinch point technology, and discusses the thermal efficiency of hydrogen production in detail. The results show that if all heat released by heat exchangers in H2SO4 and HI sections can be fully recovered and utilized, the upper bound of the thermal efficiency of the IS process is 51.9%. The pinch point temperature difference has little impact on the performance of the heat exchange network of the H2SO4 section, but greatly influences the performance of the heat exchange network of the HI section. When the pinch point temperature difference is 5°C to 20°C, the input heat duties required by the H2SO4 and HI sections are reduced by 23.9% to 25.0% and 20.8% to 50.8%, respectively, compared with those without heat exchange networks. After designing the heat exchange network, considering the recovery and utilization of a portion of waste heat, a more realistic hydrogen production efficiency of 30.0% to 37.1% corresponding to the pinch point temperature difference of 5°C to 20°C is given. Highlights Process simulation of IS cycle is conducted to analyze its energy consumption. Internal heat exchange network is designed using pinch point technology. Network performance is studied at different pinch point temperature differences. Thermal efficiency of hydrogen production is discussed in detail.

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Experimental study and development of an improved sulfur–iodine cycle integrated with HI electrolysis for hydrogen production

Cited by 34 publications

References 50 publications

Ir(IV) Sulfoxide-Pincer Complexes by Three-Electron Oxidative Additions of Br₂ and I₂. Unprecedented Trap-Free Reductive Elimination of I₂ from a formal d⁵ Metal

Ir(IV) Sulfoxide-Pincer Complexes by Three-Electron Oxidative Additions of Br₂ and I₂. Unprecedented Trap-Free Reductive Elimination of I₂ from a formal d⁵ Metal

Cu–Cl Thermochemical Water Splitting Cycle: Probing Temperature-Dependent CuCl2 Hydrolysis and Thermolysis Reaction Using In Situ XAS

Analysis of internal heat exchange network and hydrogen production efficiency of iodine–sulfur cycle for nuclear hydrogen production

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Experimental study and development of an improved sulfur–iodine cycle integrated with HI electrolysis for hydrogen production

Cited by 34 publications

References 50 publications

Ir(IV) Sulfoxide-Pincer Complexes by Three-Electron Oxidative Additions of Br2 and I2. Unprecedented Trap-Free Reductive Elimination of I2 from a formal d5 Metal

Ir(IV) Sulfoxide-Pincer Complexes by Three-Electron Oxidative Additions of Br2 and I2. Unprecedented Trap-Free Reductive Elimination of I2 from a formal d5 Metal

Cu–Cl Thermochemical Water Splitting Cycle: Probing Temperature-Dependent CuCl2 Hydrolysis and Thermolysis Reaction Using In Situ XAS

Analysis of internal heat exchange network and hydrogen production efficiency of iodine–sulfur cycle for nuclear hydrogen production

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Ir(IV) Sulfoxide-Pincer Complexes by Three-Electron Oxidative Additions of Br₂ and I₂. Unprecedented Trap-Free Reductive Elimination of I₂ from a formal d⁵ Metal

Ir(IV) Sulfoxide-Pincer Complexes by Three-Electron Oxidative Additions of Br₂ and I₂. Unprecedented Trap-Free Reductive Elimination of I₂ from a formal d⁵ Metal