Solar thermochemical reactor technology for splitting CO2

Furler, Philipp; Marxer, Daniel; Takacs, Michael; Steinfeld, Aldo

doi:10.1063/1.5067139

Cited by 9 publications

(7 citation statements)

References 11 publications

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“…The maximum CO production rate reached ~9.4 mL/g/min for oxidation in 100% CO 2 (cycle #28 in Table 1). This means that a 8 fold-increase of the fuel production rate was achieved with the studied microstructured ceria foams (microstructural characterization provided in the next section), when compared to previously reported values [18,23,24,32]. The fuel production rate can even be enhanced further (up to 9.9 mL/g/min for cycle #32) by increasing the total gas flow-rate (inducing products dilution).…”

Section: Parameters Investigated During the Oxidation Stepsupporting

confidence: 61%

“…Furthermore, the CO production rate was remarkably high, in the range of 4 to 7 mL/g/min, representing the highest rates obtained to date with ceria and thus a strong improvement in the performance of solar fuel reactors based on reticulated porous ceria. In comparison, Furler et al [23,24,32] obtained a maximal fuel production rate of 1.2 mL/g/min with more stringent operational conditions (1450°C and 10 hPa) in an electrically-heated high-flux simulator using ceria foams with dual-scale porosity. In the present study, the microstructured ceria foams were subjected to real concentrated high-flux solar radiation in a scalable solar reactor and were found to sustain fuel production cycles without any reactivity loss.…”

Section: Thermal Stability Of the Porous Ceria Foamsmentioning

confidence: 99%

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Remarkable performance of microstructured ceria foams for thermochemical splitting of H2O and CO2 in a novel high–temperature solar reactor

Haeussler

Abanades

Julbe

et al. 2020

Chemical Engineering Research and Design

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Thermochemical splitting of H 2 O and CO 2 applying redox materials constitutes a sustainable option for synthetic fuel production and CO 2 valorization. It consists of two-step process based on the creation of oxygen vacancies in non-stoichiometric oxides during solar-driven thermal reduction, followed by the material re-oxidation with H 2 O and/or CO 2 to generate syngas (H 2 /CO), the building block for a wide variety of synthetic hydrocarbon fuels. In this work, a monolithic solar reactor was designed and tested integrating reticulated porous ceria (open-cell foams) heated by concentrated solar energy. The influence of various operating parameters on the thermochemical reactor performance was investigated. Increasing the temperature or decreasing the pressure in the reduction step was found to enhance the maximum reduction extent reached by the redox material (CeO 2- ), thereby improving the fuel production capacity. In addition, a decrease of the oxidation temperature led to higher fuel production rate, despite an increase of the temperature swing between the reduction and oxidation steps. Increasing the oxidant concentration also sharply enhanced the oxidation rate. Peak CO production rate approaching 10 mL/min/g was achieved with ceria foams (exhibiting micron-sized grains forming an interconnected macroporous network within the struts) during their reoxidation upon free cooling with pure CO 2 stream (after reduction at 1400°C), thus strongly outperforming (by a factor of about x8) the previous maximum values reported to date. This result was attributed to the fine and stable granular microstructure of the reticulated ceria foams. The solar reactor reliability and robustness during hightemperature two-step redox cycling were demonstrated with an average cycle production of 5.1 mL/g of H 2 and CO, and peak solar-to-fuel efficiencies above 8%. The highly reactive reticulated foams with 10 and 20 ppi (pore per inch) were cycled for about 69 hours (51 cycles) of continuous on-sun operation without any decrease in performance, thus evidencing their noteworthy thermochemical and microstructural stability.

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Section: Parameters Investigated During the Oxidation Stepsupporting

confidence: 61%

Section: Thermal Stability Of the Porous Ceria Foamsmentioning

confidence: 99%

Remarkable performance of microstructured ceria foams for thermochemical splitting of H2O and CO2 in a novel high–temperature solar reactor

Haeussler

Abanades

Julbe

et al. 2020

Chemical Engineering Research and Design

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“…In addition, a complete re-oxidation was achieved in most of performed cycles (oxidation extent above 99%). In comparison, other studies [47][48][49] reached a peak CO production rate of 1.2 mL.g -1 .min -1 using ceria foams cycled with more favorable operating conditions for the reduction step (T red =1500°C under 10 mbar). In another study with the same reactor [27], the highest peak CO production rate reached 3.1 mL.g -1 .min -1 for CTCe, whereas a previous study [21] using cork-templated ceria granules in a tubular packed-bed solar reactor reported a peak CO production rate of 1.9 mL.g -1 .min -1 under similar conditions (reduction step at 1400°C and atmospheric pressure).…”

Section: Materials Performance In Directly-heated Solar Reactormentioning

confidence: 69%

Two-step thermochemical cycles using fibrous ceria pellets for H2 production and CO2 reduction in packed-bed solar reactors

Abanades

Haeussler

2021

Sustainable Materials and Technologies

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The thermochemical redox activity and performance of commercial-grade fibrous ceria pellets were determined including fuel production rates and yields from H 2 O and CO 2 dissociation. Two solar reactors integrating the ceria pellets undergoing two-step thermochemical cycling (with temperatureswing between alternating redox steps) were experimentally tested. They consisted of packed-bed tubular and cavity-type solar reactors with direct or indirect heating of the reacting materials. The obtained fuel production rates compared favorably with the performance of other previously considered microstructured ceria materials such as templated foams, sintered felts, bioinspired or ordered macroporous morphologies. H 2 production rates reached 2.3 mL.g -1 .min -1 (with H 2 /O 2 ratios approaching 2) in the indirectly-heated tubular reactor after reduction at 1400°C and oxidation upon free cooling below 950°C in steam atmosphere (57% molar content). The highest fuel production rate (~9.5 mL.g -1 .min -1 ) and peak solar-to-fuel energy efficiency (~9.4%) were reached in the directlyirradiated cavity-type reactor (with a reduction step at 1400°C under reduced pressure, and an oxidation step in pure CO 2 below 950°C). The reduction extent was favored at low p O2 ( up to 0.056) and the fuel yields were thus improved notably (up to 315 µmol/g) by decreasing the total pressure below 0.1 bar during the reduction step. The fuel production rate increased when the oxidation temperature decreased (because the reaction was thermodynamically more favorable). An increase in CO 2 partial pressure further promoted the oxidation kinetics (and decreased the p CO /p CO2 ratio, thus shifting the thermodynamic equilibrium toward CO product). The fibrous ceria structures exhibited stable morphologies with high fuel production performance similar to less scalable porous structures, thus offering the potential for versatile applications in packed-bed solar reactors.

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“…CeO2 → CeO2-δ [211][212][213][214][215] Doped ceria MxCe1-xO2 → MxCe1-xO2-δ [216][217][218] Perovskite ABO3 → ABO3-δ [219][220] Volatile reactions generally demonstrate a better oxygen exchange capability than nonvolatile reactions and the reduction process is thermodynamically more favourable. However, a highly demanding quenching step is necessary to avoid recombination and material loss is inevitable due to gas-phase deposition on the walls of the reactor, volatile cycles are therefore not viable for large-scale and long-term solar thermal hydrogen production.…”

Section: Ceriamentioning

confidence: 99%

Research advances towards large-scale solar hydrogen production from water

et al. 2019

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Solar hydrogen production from water is a sustainable alternative to traditional hydrogen production route using fossil fuels. However, there is still no existing large-scale solar hydrogen production system to compete with its counterpart. In this Review, recent developments of four potentially cost-effective pathways towards large-scale solar hydrogen production, viz. photocatalytic, photobiological, solar thermal and photoelectrochemical routes, are discussed, respectively. The limiting factors including efficiency, scalability and durability for scale-up are assessed along with the field performance of the selected systems. Some benchmark studies are highlighted, mostly addressing one or two of the limiting factors, as well as a few recent examples demonstrating upscaled solar hydrogen production systems and emerging trends towards large-scale hydrogen production. A techno-economic analysis provides a critical comparison of the levelized cost of hydrogen output via each of the four solar-to-hydrogen conversion pathways.

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Solar thermochemical reactor technology for splitting CO2

Cited by 9 publications

References 11 publications

Remarkable performance of microstructured ceria foams for thermochemical splitting of H2O and CO2 in a novel high–temperature solar reactor

Remarkable performance of microstructured ceria foams for thermochemical splitting of H2O and CO2 in a novel high–temperature solar reactor

Two-step thermochemical cycles using fibrous ceria pellets for H2 production and CO2 reduction in packed-bed solar reactors

Research advances towards large-scale solar hydrogen production from water

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