Mechanisms of synthesis gas production via thermochemical cycles over La0·3Sr0·7Co0·7Fe0·3O3

Khamhangdatepon, Tatiya; Tongnan, Vut; Hartley, Matthew; Sornchamni, Thana; Siri-Nguan, Nuchanart; Laosiripojana, Navadol; Li, K.; Hartley, Unalome Wetwatana

doi:10.1016/j.ijhydene.2019.12.148

Cited by 5 publications

(11 citation statements)

References 34 publications

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“…However, both their re-oxidation extent and production stability are low, making them unsuitable for thermochemical applications requiring numerous consecutive redox cycles [11]. Strategies for doping the lanthanum cobalt perovskites with Ca 2+ or Sr 2+ in A-site or with Cr and Fe in B-site have been investigated, but in all cases the fuel production decreased over cycles [10][11][12][13][14][15][16]. Lanthanum-manganite perovskites doped with strontium (A-site substitution) have been extensively studied for assessing their thermochemical performance.…”

Section: Introductionmentioning

confidence: 99%

Two-step CO2 and H2O splitting using perovskite-coated ceria foam for enhanced green fuel production in a porous volumetric solar reactor

Haeussler

Abanades

Julbe

et al. 2020

Journal of CO2 Utilization

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Solar thermochemical cycles offer a viable option for the production of green synthetic fuels from CO 2 and H 2 O. Two-step cycles using redox materials consist of a high-temperature reduction creating oxygen vacancies, followed by a re-oxidation step with an oxidant gas (CO 2 and/or H 2 O), resulting in CO and/or H 2 production. This study focuses on the thermochemical performance in a solar reactor of a new kind of composite reactive material: reticulated ceria foam with uniform perovskite coating, forming a dual-phase layered heterostructure. La 0.5 Sr 0.5 Mn 0.9 Mg 0.1 O 3 (LSMMg) was selected as perovskite coating due to its high fuel productivity and thermochemical stability upon cycling. The perovskite coating improves the reduction step by increasing the reduction extent reached by the reactive material. The results revealed significant enhancement of oxygen exchange in the dual-phase composite material during reduction compared to individual components. The enhanced reduction extent had a beneficial effect on the oxygen release rate and the total amount of fuel produced by CO 2 and H 2 O splitting, whereas an adverse impact on the peak rate during H 2 /CO evolution was noticed. Decreasing the reduction pressure allowed enhancing the non-stoichiometric oxygen extent, while the re-oxidation extent increased with the inlet oxidant molar fraction. With suitable operating conditions (reduction at 0.100 bar and oxidation in 100% CO 2 ), the LSMMg-coated ceria foam produced a higher amount of fuel but with lower fuel production rate in comparison with pure ceria foam. This study points out the beneficial effects of composite redox materials consisting of LSMMg-coated ceria foam in enhancing the oxygen exchange capacity of ceria for solar fuel production.

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Section: Introductionmentioning

confidence: 99%

Two-step CO2 and H2O splitting using perovskite-coated ceria foam for enhanced green fuel production in a porous volumetric solar reactor

Haeussler

Abanades

Julbe

et al. 2020

Journal of CO2 Utilization

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“…It was noticed that the solid conversion was decreased when the CO 2 content in the feed increased; thus, only a 3 to 1 ratio of H 2 O to CO 2 could provide 100% conversion. This phenomenon was due to the CO 2 blockage caused by CO 2 adsorption in the high CO 2 content feed stream [15].…”

Section: Reactivity Studymentioning

confidence: 99%

“…As such, they present a smart method for fuel generation at high rates and efficiencies without noble metal catalysts [3], which, via redox chemical reactions, additionally go around the CO-H 2 -O 2 separation problem [4]. Two step thermochemical cycles support for metal oxide redox pairs (mostly La/La 2 O 3 , Sr/SrO 2 , Co/CoO 3 Zn/ZnO, Ce 2 O 3 /CeO 2 , FeO/Fe 3 O 4 and SnO/SnO 2 ), to date, have mostly been reported, which are determined by high temperature process heat [4][5][6][7][8][9][10][11][12][13][14][15]. The major challenges are the requirement of rapid reduction in gaseous products to avoid their recombination [4] and the entire conversion of metal to metal-oxide to execute fast carbon monoxide and hydrogen production rates [10].…”

Section: Introductionmentioning

confidence: 99%

“…However, both their re-oxidation coverage and generation stability are low, making them unfit for thermochemical applications, which have numerous successive redox cycles [16]. An approach for incorporating lanthanum-cobalt with Ca 2+ or Sr 2+ in the A-site or with Cr and Fe in the B-site was reported, but in all composites, the fuel generation decreased over cycles [15][16][17][18][19][20][21]. Further, researchers are focused on La-Co with multi metal/metal oxides.…”

Section: Introductionmentioning

confidence: 99%

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A Dual Reactor for Isothermal Thermochemical Cycles of H2O/CO2 Co-Splitting Using La0.3Sr0.7Co0.7Fe0.3O3 as an Oxygen Carrier

et al. 2021

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Catalytic performance of La0.3Sr0.7Co0.7Fe0.3O3 (LSCF3773 or LSCF) catalyst for syngas production via two step thermochemical cycles of H2O and CO2 co-splitting was investigated. Oxygen storage capacity (OSC) was found to depend on reduction temperature, rather than the oxidation temperature. The highest oxygen vacancy (Δδ) was achieved when the reduction and oxidation temperature were both fixed at 900 °C with the feed ratio (H2O to CO2) of 3 to 1, with an increasing amount of CO2 in the feed mixture. CO productivity reached its plateau at high ratios of H2O to CO2 (1:1, 1:2, and 1:2.5), while the total productivities were reduced with the same ratios. This indicated the existence of a CO2 blockage, which was the result of either high Ea of CO2 dissociation or high Ea of CO desorption, resulting in the loss in active species. From the results, it can be concluded that H2O and CO2 splitting reactions were competitive reactions. Ea of H2O and CO2 splitting was estimated at 31.01 kJ/mol and 48.05 kJ/mol, respectively, which agreed with the results obtained from the experimentation of the effect of the oxidation temperature. A dual-reactors system was applied to provide a continuous product stream, where the operation mode was switched between the reduction and oxidation step. The isothermal thermochemical cycles process, where the reduction and oxidation were performed at the same temperature, was also carried out in order to increase the overall efficiency of the process. The optimal time for the reduction and oxidation step was found to be 30 min for each step, giving total productivity of the syngas mixture at 28,000 μmol/g, approximately.

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“…[20] Researchers then sought new materials that can achieve high fuel yield at appreciably lower reduction temperatures; examples include doped ceria [21][22][23][24][25][26] and perovskites. [27][28][29][30][31][32][33][34][35][36] Although these materials could be reduced at more easily achieved conditions, they were more difficult to oxidize, necessitating a lower temperature and/or larger supply of oxidizer. [27,28] Consequently, the energy burden only shifted from the reduction to the oxidation step, resulting in little or no improvement in process efficiency.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Guiding Principles for Designing Nonstoichiometric Redox Materials for Solar Thermochemical Fuel Production: Ceria, Perovskites, and Beyond

Wheeler

Kumar

et al. 2021

Energy Tech

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Two‐step solar thermochemical water splitting is a promising pathway for renewable fuel production due to its potential for high thermal efficiency via full‐spectrum sunlight utilization. Such a promise critically relies on simultaneous innovation in the redox materials and the reactor systems. Most prior efforts on material design are focused on improving the fuel yield at lower reduction temperatures. However, developing materials with both high fuel output and efficiency remains a key challenge, requiring a rigorous understanding of the effects of material thermodynamic properties. Herein, a generic thermodynamic framework is described to decipher the material effects by studying both the state‐of‐the‐art and hypothetical materials within a counterflow reactor system. A global efficiency map is presented for redox materials, revealing inevitable tradeoffs among competing factors such as thermal losses, sweep gas and oxidizer demand, solid preheating, and reduction enthalpy. The choice of the most efficient material is closely linked to the system conditions. Ceria‐based materials outperform perovskites under most scenarios, and the optimal hypothetical materials tend to favor higher reduction enthalpies and entropies than existing materials. This work offers a valuable material design roadmap to identify solutions toward efficient solar fuel production.

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Mechanisms of synthesis gas production via thermochemical cycles over La0·3Sr0·7Co0·7Fe0·3O3

Cited by 5 publications

References 34 publications

Two-step CO2 and H2O splitting using perovskite-coated ceria foam for enhanced green fuel production in a porous volumetric solar reactor

Two-step CO2 and H2O splitting using perovskite-coated ceria foam for enhanced green fuel production in a porous volumetric solar reactor

A Dual Reactor for Isothermal Thermochemical Cycles of H2O/CO2 Co-Splitting Using La0.3Sr0.7Co0.7Fe0.3O3 as an Oxygen Carrier

Thermodynamic Guiding Principles for Designing Nonstoichiometric Redox Materials for Solar Thermochemical Fuel Production: Ceria, Perovskites, and Beyond

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